JP3937482B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

【００１６】
【化２】

【００１７】
【化３】

【００１８】
【化４】

【００１９】
【化５】

【００２０】
一般式（１）で表される化合物は多くの場合試薬として市販されている。代表的な試薬メーカーもしくは代理店としては和光純薬工業（株）、東京化成工業（株）、シグマ−アルドリッチジャパン（株）等が挙げられる。以下に試薬として入手できない化合物の合成法について具体例を挙げて説明するが、本発明はこれらに限定されない。
【００２１】
例示化合物（２）の合成
チオジフェノール２１．７ｇ、パラトルエンスルホン酸メチル４１ｇ、Ｎ，Ｎ−ジメチルホルムアミド２００ｍｌ、および炭酸カリウム５４ｇを混合し、１００℃で１時間加熱攪拌した。次に、反応混合物を水にあけ析出した白色固体を濾取した。該固体を乾燥後、酢酸エチル−ヘキサン混合溶媒で再結晶し例示化合物（２）１４ｇを得た。
【００２２】
次に酸化電位について説明する。本発明者らは以下の方法にて還元剤の酸化電位を測定した。エチレンカーボネートとジエチルカーボネートの２０：８０混合液（重量比）にＬｉＰＦ₆ を溶解し１モル／リットルの電解質を調製した。この電解質５０ｇに本発明の例示化合物（１）１８ｍｇを溶解し、２ｘ１０^-3モル／リットルの溶液（試料１）を調製した。次に本発明の例示化合物（１）の代わりに表１の化合物を用いる以外は同様の方法で試料２から試料１１を調製した。
【００２３】
試料をそれぞれアルゴンガスでバブリングした後、北斗電工製ポテンシオスタットＨＡ−３０１型、およびファンクションジェネレーターＨＢ−１０４型を用いてサイクリックボルタンメトリーを行った。参照電極には金属リチウム箔を、作用極にはグラッシーカーボン電極を用いた。毎秒９０ｍＶの速度で＋３Ｖより＋４．４Ｖまで電位を掃引した。可逆性のない還元剤を同列で評価するために、半波電位ではなくアノード電流の立ち上がりの電位（アノード電流のピーク値に対して５パーセントの電流変化が認められた時の電位）の値をもって酸化電位（Ｅａｐｐ）とした。
【００２４】
【表１】

【００２５】
【化６】

【００２６】
本発明者らが主張する酸化電位とサイクル性改良効果、および容量との関係は後述の実施例で示す。
【００２７】
次に還元剤の添加方法、添加量について説明する。本発明では還元剤は正極、負極、電解質のいずれに添加しても良いが、推定される作用機構から考えて正極または電解質に添加する事が好ましく、電解液に添加する事が特に好ましい。
【００２８】
添加量は任意に選択する事ができるが、電解液に添加した場合の濃度としては０．１ミリモル／リットル以上、５０ミリモル／リットル以下が好ましい。１ミリモル／リットル以上、３０ミリモル／リットル以下が特に好ましい。
正極に添加した場合は、正極活物質に対して０．０１重量パーセント以上、５重量パーセント以下、０．１重量パーセント以上が好ましく、２重量パーセント以下がより好ましい。
【００２９】
以下、本発明の非水電解液二次電池の製造方法について説明する。
本発明の非水電解液二次電池は、正負の電極シートをセパレーターと共に巻回したもの（巻回群）を電池缶に挿入し、缶と電極を電気的に接続し、電解液を注入した後封口して作成する。また、必要に応じて各種の部材（封口板、リード板、ガスケット、外装材等）が用いられる。
【００３０】
正（負）の電極シートは正（負）極の合剤を集電体の上に塗布、乾燥、圧縮する事により作成する事ができる。
合剤の調製は正極（あるいは負極）材料および導電剤を混合し、結着剤（樹脂粉体のサスペンジョンまたはエマルジョン状のもの）、および分散媒を加えて混練混合し、引続いて、ミキサー、ホモジナイザー、ディゾルバー、プラネタリミキサー、ペイントシェイカー、サンドミル等の攪拌混合機、分散機で分散して行うことが出来る。分散媒としては水もしくは有機溶媒が用いられるが、水が好ましい。このほか、適宜充填剤、イオン導電剤、圧力増強剤等の添加剤を添加しても良い。
塗布は種々の方法で行うことが出来るが、例えば、リバースロール法、ダイレクトロール法、ブレード法、ナイフ法、エクストルージョン法、カーテン法、グラビア法、バー法、ディップ法及びスクイーズ法を挙げることが出来る。ブレード法、ナイフ法及びエクストルージョン法が好ましい。塗布は、０．１〜１００ｍ／分の速度で実施されることが好ましい。この際、合剤ペーストの液物性、乾燥性に合わせて、上記塗布方法を選定することにより、良好な塗布層の表面状態を得ることが出来る。その塗布層の厚み、長さや巾は、電池の大きさにより決められる。典型的な塗布層の厚みは乾燥後圧縮された状態で１０〜１０００μｍである。
塗布後の電極シートは、熱風、真空、赤外線、遠赤外線、電子線及び低湿風の作用により乾燥、脱水される。これらの方法は単独あるいは組み合わせて用いることが出来る。乾燥温度は８０〜３５０℃の範囲が好ましく、特に１００〜２５０℃の範囲が好ましい。乾燥後の含水量は２０００ｐｐｍ以下が好ましく、５００ｐｐｍ以下がより好ましい。
電極シートの圧縮は、一般に採用されているプレス方法を用いることが出来るが、特に金型プレス法やカレンダープレス法が好ましい。プレス圧は、特に限定されないが、１０ｋｇ／ｃｍ² 〜３ｔ／ｃｍ² が好ましい。カレンダープレス法のプレス速度は、０．１〜５０ｍ／分が好ましい。プレス温度は、室温〜２００℃が好ましい。
【００３１】
本発明で用いられる正極材料はリチウム含有遷移金属酸化物である。好ましくはＴｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｍｏ、Ｗから選ばれる少なくとも１種の遷移金属元素とリチウムとを主として含有する酸化物であって、リチウムと遷移金属のモル比が０．３乃至２．２の化合物である。より好ましくは、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉから選ばれる少なくとも１種の遷移金属元素とリチウムとを主として含有する酸化物であって、リチウムと遷移金属のモル比が０．３乃至２．２の化合物である。なお主として存在する遷移金属に対し３０モルパーセント未満の範囲でＡｌ、Ｇａ、Ｉｎ、Ｇｅ、Ｓｎ、Ｐｂ、Ｓｂ、Ｂｉ、Ｓｉ、Ｐ、Ｂなどを含有していても良い。さらに好ましいリチウム含有遷移金属酸化物は、Ｌｉ_x ＣｏＯ₂ 、Ｌｉ_x ＮｉＯ₂ 、Ｌｉ_x ＭｎＯ₂ 、Ｌｉ_x Ｃｏ_a Ｎｉ_1-a Ｏ₂ 、Ｌｉ_x Ｃｏ_b Ｖ_1-b Ｏ_z 、Ｌｉ_x Ｃｏ_b Ｆｅ_1-b Ｏ₂ 、Ｌｉ_x Ｍｎ₂ Ｏ₄ 、Ｌｉ_x Ｍｎ_c Ｃｏ_2-c Ｏ₄ 、Ｌｉ_x Ｍｎ_c Ｎｉ_2-c Ｏ₄ 、Ｌｉ_x Ｍｎ_c Ｖ_2-c Ｏ₄ 、Ｌｉ_x Ｍｎ_c Ｆｅ_2-c Ｏ₄ （ここでｘ＝０．０２〜１．２、ａ＝０．１〜０．９、ｂ＝０．８〜０．９８、ｃ＝１．６〜１．９６、ｚ＝２．０１〜２．３）である。
最も好ましいリチウム含有遷移金属酸化物としては、Ｌｉ_x ＣｏＯ₂ 、Ｌｉ_x ＮｉＯ₂ 、Ｌｉ_x ＭｎＯ₂ 、Ｌｉ_x Ｃｏ_a Ｎｉ_1-a Ｏ₂ 、Ｌｉ_x Ｍｎ₂ Ｏ₄ 、Ｌｉ_x Ｃｏ_b Ｖ_1-b Ｏ_z （ｘ＝０．０２〜１．２、ａ＝０．１〜０．９、ｂ＝０．９〜０．９８、ｚ＝２．０１〜２．３）があげられる。なおｘの値は充放電開始前の値であり、充放電により増減する。
【００３２】
本発明で用いる正極活物質は、リチウム化合物と遷移金属化合物を混合、焼成する方法や溶液反応により合成することができるが、特に焼成法が好ましい。
焼成の為の詳細は、特開平６−６０、８６７号の段落３５、特開平７−１４，５７９号等に記載されており、これらの方法を用いることができる。焼成によって得られた正極活物質は水、酸性水溶液、アルカリ性水溶液、有機溶剤にて洗浄した後使用してもよい。
更に、遷移金属酸化物に化学的にリチウムイオンを挿入する方法としては、リチウム金属、リチウム合金やブチルリチウムと遷移金属酸化物と反応させることにより合成する方法であっても良い。
【００３３】
本発明で用いる正極活物質の平均粒子サイズは特に限定されないが、０．１〜５０μｍが好ましい。０．５〜３０μｍの粒子の体積が９５％以上であることが好ましい。粒径３μｍ以下の粒子群の占める体積が全体積の１８％以下であり、かつ１５μｍ以上２５μｍ以下の粒子群の占める体積が、全体積の１８％以下であることが更に好ましい。比表面積としては特に限定されないが、ＢＥＴ法で０．０１〜５０ｍ² ／ｇが好ましく、特に０．２ｍ² ／ｇ〜１ｍ² ／ｇが好ましい。また正極活物質５ｇを蒸留水１００ｍｌに溶かした時の上澄み液のｐＨとしては７以上１２以下が好ましい。
【００３４】
本発明の正極活物質を焼成によって得る場合、焼成温度としては５００〜１５００℃であることが好ましく、さらに好ましくは７００〜１２００℃であり、特に好ましくは７５０〜１０００℃である。焼成時間としては４〜３０時間が好ましく、さらに好ましくは６〜２０時間であり、特に好ましくは６〜１５時間である。
【００３５】
本発明で用いられる負極材料としては、リチウムイオンを吸蔵・放出できる化合物であればよい。このような負極材料の例としては金属リチウム、リチウム合金、炭素質化合物、無機酸化物、無機カルコゲン化合物、金属錯体、有機高分子化合物が挙げられる。これらは単独でも、組み合わせて用いてもよい。
【００３６】
本発明においては負極材料として周期表１、２、１３、１４、１５族原子から選ばれる三種以上の原子を含む主として非晶質カルコゲン化合物または非晶質酸化物が特に好ましく用いられる。ここで言う主として非晶質とはＣｕＫα線を用いたＸ線回折法で２θ値で２０°から４０°に頂点を有するブロードな散乱帯を有する物であり、結晶性の回折線を有してもよい。好ましくは２θ値で４０°以上７０°以下に見られる結晶性の回折線の内最も強い強度が、２θ値で２０°以上４０°以下に見られるブロードな散乱帯の頂点の回折線強度の５００倍以下であることが好ましく、さらに好ましくは１００倍以下であり、特に好ましくは５倍以下であり、最も好ましくは 結晶性の回折線を有さないことである。
【００３７】
上記のカルコゲン化合物、酸化物は、Ｂ、Ａｌ、Ｇａ、Ｉｎ、Ｔｌ、Ｓｉ、Ｇｅ、Ｓｎ、Ｐｂ、Ｐ、Ａｓ、Ｓｂ、Ｂｉの中の２種以上の元素を主体とする複合カルコゲン化合物、複合酸化物がより好ましい。特に好ましいのは、Ｂ、Ａｌ、Ｓｉ、Ｇｅ、Ｓｎ、Ｐの中の２種以上の元素を主体とする複合カルコゲン化合物もしくは酸化物である。これらの複合カルコゲン化合物、複合酸化物は、主として非晶質構造を修飾するために周期律表の１族から２族の元素から選ばれた少なくとも１種の元素を含む。
【００３８】
上記の負極材料の中で、Ｓｎを主体とする非晶質の複合酸化物が好ましく、次の一般式（３）で表される。
一般式（３） ＳｎＭ³ _c Ｍ⁴ _d Ｏ_t
式中、Ｍ³ はＡｌ、Ｂ、Ｐ、Ｇｅの少なくとも１種を、Ｍ⁴ は周期律表第１族元素、第２族元素の少なくとも１種を表し、ｃは０．２以上、２以下の数、ｄは０．０１以上、１以下の数で、０．２＜ｃ＋ｄ＜２、ｔは１以上６以下の数を表す。
【００３９】
本発明の非晶質複合酸化物は、焼成法、溶液法のいずれの方法も採用することができるが、焼成法がより好ましい。焼成法では、一般式（１）に記載された元素の酸化物あるいは化合物をよく混合した後、焼成して非晶質複合酸化物を得るのが好ましい。
【００４０】
焼成条件としては、昇温速度として昇温速度毎分５℃以上２００℃以下であることが好ましく、かつ焼成温度としては５００℃以上１５００℃以下であることが好ましく、かつ焼成時間としては１時間以上１００時間以下であることが好ましい。且つ、下降温速度としては毎分２℃以上１０⁷ ℃以下であることが好ましい。
本発明における昇温速度とは「焼成温度（℃表示）の５０％」から「焼成温度（℃表示）の８０％」に達するまでの温度上昇の平均速度であり、本発明における降温速度とは「焼成温度（℃表示）の８０％」から「焼成温度（℃表示）の５０％」に達するまでの温度降下の平均速度である。
降温は焼成炉中で冷却してもよくまた焼成炉外に取り出して、例えば水中に投入して冷却してもよい。またセラミックスプロセッシング（技報堂出版１９８７）２１７頁記載のｇｕｎ法・Ｈａｍｍｅｒ−Ａｎｖｉｌ法・ｓｌａｐ法・ガスアトマイズ法・プラズマスプレー法・遠心急冷法・ｍｅｌｔ ｄｒａｇ法などの超急冷法を用いることもできる。またニューガラスハンドブック（丸善１９９１）１７２頁記載の単ローラー法、双ローラ法を用いて冷却してもよい。焼成中に溶融する材料の場合には、焼成中に原料を供給しつつ焼成物を連続的に取り出してもよい。焼成中に溶融する材料の場合には融液を攪拌することが好ましい。
【００４１】
焼成ガス雰囲気は好ましくは酸素含有率が５体積％以下の雰囲気であり、さらに好ましくは不活性ガス雰囲気である。不活性ガスとしては例えば窒素、アルゴン、ヘリウム、クリプトン、キセノン等が挙げられる。最も好ましい不活性ガスは純アルゴンである。
【００４２】
本発明で示される化合物の平均粒子サイズは０．１〜６０μｍが好ましい。寄り詳しくは、平均粒径が０．７〜２５μｍであり、かつ全体積の６０％以上が０．５〜３０μｍであることが好ましい。また、本発明の負極活物質の粒径１μｍ以下の粒子群の占める体積は全体積の３０％以下であり、かつ粒径２０μｍ以上の粒子群の占める体積が全体積の２５％以下であることが好ましい。使用する材料の粒径は、負極の片面の合剤厚みを越えないものであることはいうまでもない。
所定の粒子サイズにするには、良く知られた粉砕機や分級機が用いられる。例えば、乳鉢、ボールミル、サンドミル、振動ボールミル、衛星ボールミル、遊星ボールミル、旋回気流型ジェットミルや篩などが用いられる。粉砕時には水、あるいはメタノール等の有機溶媒を共存させた湿式粉砕も必要に応じて行うことが出来る。所望の粒径とするためには分級を行うことが好ましい。分級方法としては特に限定はなく、篩、風力分級機などを必要に応じて用いることができる。分級は乾式、湿式ともに用いることができる。
平均粒径とは一次粒子のメジアン径のことであり、レーザー回折式の粒度分布測定装置により測定される。
【００４３】
本発明の負極材料の例を以下に示すが、本発明はこれらに限定されるものではない。
ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｋ_0.1 Ｏ_3.65、ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｎａ_0.2 Ｏ_3.7 、ＳｎＡｌ_0.4 Ｂ_0.3 Ｐ_0.5 Ｒｂ_0.2 Ｏ_3.4 、ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｃｓ_0.1 Ｏ_3.65、
ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｋ_0.1 Ｇｅ_0.05Ｏ_3.85、ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｋ_0.1 Ｍｇ_0.1 Ｇｅ_0.02Ｏ_3.83、ＳｎＡｌ_0.4 Ｂ_0.4 Ｐ_0.4 Ｏ_3.2 、ＳｎＡｌ_0.3 Ｂ_0.5 Ｐ_0.2 Ｏ_2.7 、
ＳｎＡｌ_0.3 Ｂ_0.5 Ｐ_0.2 Ｏ_2.7 、ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.3 Ｂａ_0.08Ｍｇ_0.08Ｏ_3.26、ＳｎＡｌ_0.4 Ｂ_0.4 Ｐ_0.4 Ｂａ_0.08Ｏ_3.28、ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｏ_3.6 、ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｍｇ_0.1 Ｏ_3.7
【００４４】
ＳｎＡｌ_0.5 Ｂ_0.4 Ｐ_0.5 Ｍｇ_0.1 Ｆ_0.2 Ｏ_3.65、ＳｎＢ_0.5 Ｐ_0.5 Ｌｉ_0.1 Ｍｇ_0.1 Ｆ_0.2 Ｏ_3.05、ＳｎＢ_0.5 Ｐ_0.5 Ｋ_0.1 Ｍｇ_0.1 Ｆ_0.2 Ｏ_3.05、ＳｎＢ_0.5 Ｐ_0.5 Ｋ_0.05Ｍｇ_0.05Ｆ_0.1 Ｏ_3.03、ＳｎＢ_0.5 Ｐ_0.5 Ｋ_0.05Ｍｇ_0.1 Ｆ_0.2 Ｏ_3.03、ＳｎＡｌ_0.4 Ｂ_0.5 Ｐ_0.5 Ｃｓ_0.1 Ｍｇ_0.1 Ｆ_0.2 Ｏ_3.65、ＳｎＢ_0.5 Ｐ_0.5 Ｃｓ_0.05Ｍｇ_0.05Ｆ_0.1 Ｏ_3.03、ＳｎＢ_0.5 Ｐ_0.5 Ｍｇ_0.1 Ｆ_0.1 Ｏ_3.05、ＳｎＢ_0.5 Ｐ_0.5 Ｍｇ_0.1 Ｆ_0.2 Ｏ₃ 、ＳｎＢ_0.5 Ｐ_0.5 Ｍｇ_0.1 Ｆ_0.06Ｏ_3.07、ＳｎＢ_0.5 Ｐ_0.5 Ｍｇ_0.1 Ｆ_0.14Ｏ_3.03、ＳｎＰＢａ_0.08Ｏ_3.58、ＳｎＰＫ_0.1 Ｏ_3.55、ＳｎＰＫ_0.05Ｍｇ_0.05Ｏ_3.58、ＳｎＰＣｓ_0.1 Ｏ_3.55、ＳｎＰＢａ_0.08Ｆ_0.08Ｏ_3.54、ＳｎＰＫ_0.1 Ｍｇ_0.1 Ｆ_0.2 Ｏ_3.55、ＳｎＰＫ_0.05Ｍｇ_0.05Ｆ_0.1 Ｏ_3.53、ＳｎＰＣｓ_0.1 Ｍｇ_0.1 Ｆ_0.2 Ｏ_3.55、ＳｎＰＣｓ_0.05Ｍｇ_0.05Ｆ_0.1 Ｏ_3.53、
【００４５】
Ｓｎ_1.1 Ａｌ_0.4 Ｂ_0.2 Ｐ_0.6 Ｂａ_0.08Ｆ_0.08Ｏ_3.54、Ｓｎ_1.1 Ａｌ_0.4 Ｂ_0.2 Ｐ_0.6 Ｌｉ_0.1 Ｋ_0.1 Ｂａ_0.1 Ｆ_0.1 Ｏ_3.65、Ｓｎ_1.1 Ａｌ_0.4 Ｂ_0.4 Ｐ_0.4 Ｂａ_0.08Ｏ_3.34、
Ｓｎ_1.1 Ａｌ_0.4 ＰＣｓ_0.05Ｏ_4.23、Ｓｎ_1.1 Ａｌ_0.4 ＰＫ_0.05Ｏ_4.23、Ｓｎ_1.2 Ａｌ_0.5 Ｂ_0.3 Ｐ_0.4 Ｃｓ_0.2 Ｏ_3.5 、Ｓｎ_1.2 Ａｌ_0.4 Ｂ_0.2 Ｐ_0.6 Ｂａ_0.08Ｏ_3.68、Ｓｎ_1.2 Ａｌ_0.4 Ｂ_0.2 Ｐ_0.6 Ｂａ_0.08Ｆ_0.08Ｏ_3.64、Ｓｎ_1.2 Ａｌ_0.4 Ｂ_0.2 Ｐ_0.6 Ｍｇ_0.04Ｂａ_0.04Ｏ_3.68、Ｓｎ_1.2 Ａｌ_0.4 Ｂ_0.3 Ｐ_0.5 Ｂａ_0.08Ｏ_3.58、Ｓｎ_1.3 Ａｌ_0.3 Ｂ_0.3 Ｐ_0.4 Ｎａ_0.2 Ｏ_3.3 、Ｓｎ_1.3 Ａｌ_0.2 Ｂ_0.4 Ｐ_0.4 Ｃａ_0.2 Ｏ_3.4 、Ｓｎ_1.3 Ａｌ_0.4 Ｂ_0.4 Ｐ_0.4 Ｂａ_0.2 Ｏ_3.6 、Ｓｎ_1.4 Ａｌ_0.4 ＰＫ_0.2 Ｏ_4.6 、Ｓｎ_1.4 Ａｌ_0.2 Ｂａ_0.1 ＰＫ_0.2 Ｏ_4.45、Ｓｎ_1.4 Ａｌ_0.2 Ｂａ_0.2 ＰＫ_0.2 Ｏ_4.6 、Ｓｎ_1.4 Ａｌ_0.4 ａ_0.2 ＰＫ_0.2 Ｂａ_0.1 Ｆ_0.2 Ｏ_4.9 、Ｓｎ_1.4 Ａｌ_0.4 ＰＫ_0.3 Ｏ_4.65、Ｓｎ_1.5 Ａｌ_0.2 ＰＫ_0.2 Ｏ_4.4 、Ｓｎ_1.5 Ａｌ_0.4 ＰＫ_0.1 Ｏ_4.65、Ｓｎ_1.5 Ａｌ_0.4 ＰＣｓ_0.05Ｏ_4.63、Ｓｎ_1.5 Ａｌ_0.4 ＰＣｓ_0.05Ｍｇ_0.1 Ｆ_0.24.63
【００４６】
ＳｎＳｉ_0.5 Ａｌ_0.1 Ｂ_0.2 Ｐ_0.1 Ｃａ_0.4 Ｏ_3.1 、ＳｎＳｉ_0.4 Ａｌ_0.2 Ｂ_{0. 4} Ｏ_2.7 、ＳｎＳｉ_0.5 Ａｌ_0.2 Ｂ_0.1 Ｐ_0.1 Ｍｇ_0.1 Ｏ_2.8 、ＳｎＳｉ_0.6 Ａｌ_0.2 Ｂ_0.2 Ｏ_2.8 、
ＳｎＳｉ_0.5 Ａｌ_0.3 Ｂ_0.4 Ｐ_0.2 Ｏ_3.55、ＳｎＳｉ_0.5 Ａｌ_0.3 Ｂ_0.4 Ｐ_0.5 Ｏ_4.30、ＳｎＳｉ_0.6 Ａｌ_0.1 Ｂ_0.1 Ｐ_0.3 Ｏ_3.25、ＳｎＳｉ_0.6 Ａｌ_0.1 Ｂ_0.1 Ｐ_0.1 Ｂａ_0.2 Ｏ_2.95。ＳｎＳｉ_0.6 Ａｌ_0.1 Ｂ_0.1 Ｐ_0.1 Ｃａ_0.2 Ｏ_2.95、ＳｎＳｉ_0.6 Ａｌ_0.4 Ｂ_0.2 Ｍｇ_0.1 Ｏ_3.2 、ＳｎＳｉ_0.6 Ａｌ_0.1 Ｂ_0.3 Ｐ_0.1 Ｏ_3.05、ＳｎＳｉ_0.6 Ａｌ_0.2 Ｍｇ_0.2 Ｏ_2.7 、ＳｎＳｉ_0.6 Ａｌ_0.2 Ｃａ_0.2 Ｏ_2.7 、ＳｎＳｉ_0.6 Ａｌ_0.2 Ｐ_0.2 Ｏ₃ 、
ＳｎＳｉ_0.6 Ｂ_0.2 Ｐ_0.2 Ｏ₃ 、ＳｎＳｉ_0.8 Ａｌ_0.2 Ｏ_2.9 、ＳｎＳｉ_0.8 Ａｌ_0.3 Ｂ_0.2 Ｐ_0.2 Ｏ_3.85、ＳｎＳｉ_0.8 Ｂ_0.2 Ｏ_2.9 、ＳｎＳｉ_0.8 Ｂａ_0.2 Ｏ_2.8 、ＳｎＳｉ_0.8 Ｍｇ_0.2 Ｏ_2.8 、ＳｎＳｉ_0.8 Ｃａ_0.2 Ｏ_2.8 、ＳｎＳｉ_0.8 Ｐ_0.2 Ｏ_3.1
【００４７】
Ｓｎ_0.9 Ｍｎ_0.3 Ｂ_0.4 Ｐ_0.4 Ｃａ_0.1 Ｒｂ_0.1 Ｏ_2.95、Ｓｎ_0.9 Ｆｅ_0.3 Ｂ_0.4 Ｐ_0.4 Ｃａ_0.1 Ｒｂ_0.1 Ｏ_2.95、Ｓｎ_0.8 Ｐｂ_0.2 Ｃａ_0.1 Ｐ_0.9 Ｏ_3.35、Ｓｎ_0.3 Ｇｅ_0.7 Ｂａ_0.1 Ｐ_0.9 Ｏ_3.35、Ｓｎ_0.9 Ｍｎ_0.1 Ｍｇ_0.1 Ｐ_0.9 Ｏ_3.35、Ｓｎ_0.2 Ｍｎ_0.8 Ｍｇ_0.1 Ｐ_0.9 Ｏ_3.35、Ｓｎ_0.7 Ｐｂ_0.3 Ｃａ_0.1 Ｐ_0.9 Ｏ_3.35、Ｓｎ_0.2 Ｇｅ_0.8 Ｂａ_0.1 Ｐ_0.9 Ｏ_3.35。
【００４８】
上記焼成されて得られた化合物の化学式は、測定方法として誘導結合プラズマ（ＩＣＰ）発光分光分析法、簡便法として、焼成前後の粉体の重量差から算出できる。
【００４９】
本発明で使用される導電剤は、構成された電池において化学変化を起こさない電子伝導性材料であれば何でもよい。具体例としては、鱗状黒鉛、鱗片状黒鉛、土状黒鉛等の天然黒鉛、石油コークス、石炭コークス、セルロース類、糖類、メソフェーズピッチ等の高温焼成体、気相成長黒鉛等の人工黒鉛等のグラファイト類、アセチレンブラック、ファーネスブラック、ケッチェンブラック、チャンネルブラック、ランプブラック、サーマルブラック等のカーボンブラック類、アスファルトピッチ、コールタール、活性炭、メソフューズピッチ、ポリアセン等の炭素材料、金属繊維等の導電性繊維類、銅、ニッケル、アルミニウム、銀等の金属粉類、酸化亜鉛、チタン酸カリウム等の導電性ウィスカー類、酸化チタン等の導電性金属酸化物等を挙げる事ができる。これらの中では、グラファイトやカーボンブラックが好ましい。これらは単独で用いても良いし、混合物として用いても良い。
導電剤の合剤層への添加量は、負極材料または正極材料に対し６〜５０重量％であることが好ましく、特に６〜３０重量％であることが好ましい。カーボンブラックやグラファイトでは、６〜２０重量％であることが特に好ましい。
【００５０】
本発明では電極合剤を保持するために結着剤を用いる。結着剤の例としては、多糖類、熱可塑性樹脂及びゴム弾性を有するポリマー等が挙げられる。好ましい結着剤としては、でんぷん、カルボキシメチルセルロース、セルロース、ジアセチルセルロース、メチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、アルギン酸Ｎａ、ポリアクリル酸、ポリアクリル酸Ｎａ、ポリビニルフェノール、ポリビニルメチルエーテル、ポリビニルアルコール、ポリビニルピロリドン、ポリアクリルアミド、ポリヒドロキシ（メタ）アクリレート、スチレンーマレイン酸共重合体等の水溶性ポリマー、ポリビニルクロリド、ポリテトラフルロロエチレン、ポリフッ化ビニリデン、テトラフロロエチレン−ヘキサフロロプロピレン共重合体、ビニリデンフロライド−テトラフロロエチレン−ヘキサフロロプロピレン共重合体、ポリエチレン、ポリプロピレン、エチレン−プロピレン−ジエンターポリマー（ＥＰＤＭ）、スルホン化ＥＰＤＭ、ポリビニルアセタール樹脂、メチルメタアクリレート、２ーエチルヘキシルアクリレート等の（メタ）アクリル酸エステルを含有する（メタ）アクリル酸エステル共重合体、（メタ）アクリル酸エステル−アクリロニトリル共重合体、ビニルアセテート等のビニルエステルを含有するポリビニルエステル共重合体、スチレンーブタジエン共重合体、アクリロニトリルーブタジエン共重合体、ポリブタジエン、ネオプレンゴム、フッ素ゴム、ポリエチレンオキシド、ポリエステルポリウレタン樹脂、ポリエーテルポリウレタン樹脂、ポリカーボネートポリウレタン樹脂、ポリエステル樹脂、フェノール樹脂、エポキシ樹脂等のエマルジョン（ラテックス）あるいはサスペンジョンを挙げることが出来る。特にポリアクリル酸エステル系のラテックス、カルボキシメチルセルロース、ポリテトラフルオロエチレン、ポリフッ化ビニリデンが挙げられる。
これらの結着剤は単独または混合して用いることが出来る。結着剤の添加量が少ないと電極合剤の保持力・凝集力が弱い。多すぎると電極体積が増加し電極単位体積あるいは単位重量あたりの容量が減少する。このような理由で結着剤の添加量は１〜３０重量％が好ましく、特に２〜１０重量％が好ましい。
【００５１】
充填剤は、構成された電池において、化学変化を起こさない繊維状材料であれば何でも用いることができる。通常、ポリプロピレン、ポリエチレンなどのオレフィン系ポリマー、ガラス、炭素などの繊維が用いられる。フィラーの添加量は特に限定されないが、０〜３０重量％が好ましい。
イオン導電剤は、無機及び有機の固体電解質として知られている物を用いることができ、詳細は電解液の項に記載されている。
圧力増強剤は、電池の内圧を上げる化合物であり、炭酸塩が代表例である。
【００５２】
本発明で使用できる集電体は正極はアルミニウム、ステンレス鋼、ニッケル、チタン、またはこれらの合金であり、負極は銅、ステンレス鋼、ニッケル、チタン、またはこれらの合金である。集電体の形態は箔、エキスパンドメタル、パンチングメタル、もしくは金網である。特に、正極にはアルミニウム箔、負極には銅箔が好ましい。
【００５３】
本発明で使用できるセパレータは、イオン透過度が大きく、所定の機械的強度を持ち、絶縁性の薄膜であれば良く、材質として、オレフィン系ポリマー、フッ素系ポリマー、セルロース系ポリマー、ポリイミド、ナイロン、ガラス繊維、アルミナ繊維が用いられ、形態として、不織布、織布、微孔性フィルムが用いられる。特に、材質として、ポリプロピレン、ポリエチレン、ポリプロピレンとポリエチレンの混合体、ポリプロピレンとテフロンの混合体、ポリエチレンとテフロンの混合体が好ましく、形態として微孔性フィルムであるものが好ましい。特に、孔径が０．０１〜１μｍ、厚みが５〜５０μｍの微孔性フィルムが好ましい。
【００５４】
電解液は一般に支持塩と溶媒から構成される。リチウム二次電池における支持塩はリチウム塩が主として用いられる。
本発明で使用出来るリチウム塩としては、例えば、ＬｉＣｌＯ₄ 、ＬｉＢＦ₄ 、ＬｉＰＦ₆ 、ＬｉＣＦ₃ ＳＯ₃ 、ＬｉＣＦ₃ ＣＯ₂ 、ＬｉＡｓＦ₆ 、ＬｉＳｂＦ₆ 、ＬｉＢ₁₀Ｃｌ₁₀、低級脂肪族カルボン酸リチウム、ＬｉＡｌＣｌ₄ 、ＬｉＣｌ、ＬｉＢｒ、ＬｉＩ、クロロボランリチウム、四フェニルホウ酸リチウムなどのＬｉ塩を上げることが出来、これらの一種または二種以上を混合して使用することができる。なかでもＬｉＢＦ₄ 及び／あるいはＬｉＰＦ₆ を溶解したものが好ましい。
支持塩の濃度は、特に限定されないが、電解液１リットル当たり０．２〜３モルが好ましい。
【００５５】
本発明で使用できる溶媒としては、プロピレンカ−ボネ−ト、エチレンカーボネ−ト、ブチレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネート、γ−ブチロラクトン、ギ酸メチル、酢酸メチル、１，２−ジメトキシエタン、テトラヒドロフラン、２−メチルテトラヒドロフラン、ジメチルスルホキシド、１，３−ジオキソラン、ホルムアミド、ジメチルホルムアミド、ジオキソラン、ジオキサン、アセトニトリル、ニトロメタン、エチルモノグライム、リン酸トリエステル、トリメトキシメタン、ジオキソラン誘導体、スルホラン、３−メチル−２−オキサゾリジノン、プロピレンカーボネート誘導体、テトラヒドロフラン誘導体、エチルエーテル、１，３−プロパンサルトンなどの非プロトン性有機溶媒を挙げることができ、これらの一種または二種以上を混合して使用する。これらのなかでは、カーボネート系の溶媒が好ましく、環状カーボネートと非環状カーボネートを混合して用いるのが特に好ましい。環状カーボネートとしてはエチレンカーボネート、プロピレンカーボネートが好ましい。また、非環状カーボネートとしては、ジエチルカーボネート、ジメチルカーボネート、メチルエチルカーボネートをが好ましい。
本発明で使用できる電解液としては、エチレンカーボネート、プロピレンカ−ボネ−ト、１，２−ジメトキシエタン、ジメチルカーボネートあるいはジエチルカーボネートを適宜混合した電解液にＬｉＣＦ₃ ＳＯ₃ 、ＬｉＣｌＯ₄ 、ＬｉＢＦ₄ および／またはＬｉＰＦ₆ を含む電解液が好ましい。特にプロピレンカーボネートもしくはエチレンカーボネートの少なくとも一方とジメチルカーボネートもしくはジエチルカーボネートの少なくとも一方の混合溶媒に、ＬｉＣＦ₃ ＳＯ₃ 、ＬｉＣｌＯ₄ 、もしくはＬｉＢＦ₄ の中から選ばれた少なくとも一種の塩とＬｉＰＦ₆ を含む電解液が好ましい。これら電解液を電池内に添加する量は特に限定されず、正極材料や負極材料の量や電池のサイズに応じて用いることができる。
【００５６】
また、電解液の他に次の様な固体電解質も併用することができる。
固体電解質としては、無機固体電解質と有機固体電解質に分けられる。
無機固体電解質には、Ｌｉの窒化物、ハロゲン化物、酸素酸塩などがよく知られている。なかでも、Ｌｉ₃ Ｎ、ＬｉＩ、Ｌｉ₅ ＮＩ₂ 、Ｌｉ₃ Ｎ−ＬｉＩ−ＬｉＯＨ、Ｌｉ₄ ＳｉＯ₄ 、Ｌｉ₄ ＳｉＯ₄ −ＬｉＩ−ＬｉＯＨ、x Ｌｉ₃ ＰＯ₄ −(1-x)Lｉ₄ ＳｉＯ₄ 、Ｌｉ₂ ＳｉＳ₃ 、硫化リン化合物などが有効である。
【００５７】
有機固体電解質では、ポリエチレンオキサイド誘導体か該誘導体を含むポリマー、ポリプロピレンオキサイド誘導体あるいは該誘導体を含むポリマー、イオン解離基を含むポリマー、イオン解離基を含むポリマーと上記非プロトン性電解液の混合物、リン酸エステルポリマー、非プロトン性極性溶媒を含有させた高分子マトリックス材料が有効である。さらに、ポリアクリロニトリルを電解液に添加する方法もある。また、無機と有機固体電解質を併用する方法も知られている。
【００５８】
また、放電や充放電特性を改良する目的で、他の化合物を電解質に添加しても良い。例えば、ピリジン、トリエチルフォスファイト、トリエタノールアミン、環状エーテル、エチレンジアミン、ｎ−グライム、ヘキサリン酸トリアミド、ニトロベンゼン誘導体、硫黄、キノンイミン染料、Ｎ−置換オキサゾリジノンとＮ, Ｎ’−置換イミダリジノン、エチレングリコールジアルキルエーテル、第四級アンモニウム塩、ポリエチレングリコ−ル、ピロール、２−メトキシエタノール、ＡｌＣｌ₃、導電性ポリマー電極活物質のモノマー、トリエチレンホスホルアミド、トリアルキルホスフィン、モルホリン、カルボニル基を持つアリール化合物、１２−クラウンー４のようなクラウンエーテル類、ヘキサメチルホスホリックトリアミドと４−アルキルモルホリン、二環性の三級アミン、オイル、四級ホスホニウム塩、三級スルホニウム塩などを挙げることができる。
【００５９】
また、電解液を不燃性にするために含ハロゲン溶媒、例えば、四塩化炭素、三弗化塩化エチレンを電解液に含ませることができる。また、高温保存に適性をもたせるために電解液に炭酸ガスを含ませることができる。
【００６０】
電解液は、全量を１回で注入してもよいが、２回以上に分けて注入することが好ましい。２回以上に分けて注入する場合、それぞれの液は同じ組成でも、違う組成（例えば、非水溶媒あるいは非水溶媒にリチウム塩を溶解した溶液を注入した後、前記溶媒より粘度の高い非水溶媒あるいは非水溶媒にリチウム塩を溶解した溶液を注入）でも良い。また、電解液の注入時間の短縮等のために、電池缶を減圧したり、電池缶に遠心力や超音波をかけることを行ってもよい。
【００６１】
本発明で使用できる電池缶および電池蓋は材質としてニッケルメッキを施した鉄鋼板、ステンレス鋼板（ＳＵＳ３０４、ＳＵＳ３０４Ｌ，ＳＵＳ３０４Ｎ、ＳＵＳ３１６、ＳＵＳ３１６Ｌ、ＳＵＳ４３０、ＳＵＳ４４４等）、ニッケルメッキを施したステンレス鋼板（同上）、アルミニウムまたはその合金、ニッケル、チタン、銅であり、形状として、真円形筒状、楕円形筒状、正方形筒状、長方形筒状である。特に、外装缶が負極端子を兼ねる場合は、ステンレス鋼板、ニッケルメッキを施した鉄鋼板が好ましく、外装缶が正極端子を兼ねる場合は、ステンレス鋼板、アルミニウムまたはその合金が好ましい。電池缶の形状はボタン、コイン、シート、シリンダー、角などのいずれでも良い。
電池缶の内圧上昇の対策として封口板に安全弁を用いることができる。この他、電池缶やガスケット等の部材に切り込みをいれる方法も利用することが出来る。この他、従来から知られている種々の安全素子（例えば、過電流防止素子として、ヒューズ、バイメタル、ＰＴＣ素子等）を備えつけても良い。
【００６２】
本発明で使用するリード板には、電気伝導性をもつ金属（例えば、鉄、ニッケル、チタン、クロム、モリブデン、銅、アルミニウム等）やそれらの合金を用いることが出来る。電池蓋、電池缶、電極シート、リード板の溶接法は、公知の方法（例、直流又は交流の電気溶接、レーザー溶接、超音波溶接）を用いることが出来る。封口用シール剤は、アスファルト等の従来から知られている化合物や混合物を用いることが出来る。
【００６３】
本発明で使用できるガスケットは、材質として、オレフィン系ポリマー、フッ素系ポリマー、セルロース系ポリマー、ポリイミド、ポリアミドであり、耐有機溶媒性及び低水分透過性から、オレフィン系ポリマーが好ましく、特にプロピレン主体のポリマーが好ましい。さらに、プロピレンとエチレンのブロック共重合ポリマーであることが好ましい。
【００６４】
本発明の電池は必要に応じて外装材で被覆される。外装材としては、熱収縮チューブ、粘着テープ、金属フィルム、紙、布、塗料、プラスチックケース等がある。また、外装の少なくとも一部に熱で変色する部分を設け、使用中の熱履歴がわかるようにしても良い。
【００６５】
本発明の電池は必要に応じて複数本を直列及び／または並列に組み電池パックに収納される。電池パックには正温度係数抵抗体、温度ヒューズ、ヒューズ及び／または電流遮断素子等の安全素子の他、安全回路（各電池及び／または組電池全体の電圧、温度、電流等をモニターし、必要なら電流を遮断する機能を有す回路）を設けても良い。また電池パックには、組電池全体の正極及び負極端子以外に、各電池の正極及び負極端子、組電池全体及び各電池の温度検出端子、組電池全体の電流検出端子等を外部端子として設けることもできる。また電池パックには、電圧変換回路（ＤＣ−ＤＣコンバータ等）を内蔵しても良い。また各電池の接続は、リード板を溶接することで固定しても良いし、ソケット等で容易に着脱できるように固定しても良い。さらには、電池パックに電池残存容量、充電の有無、使用回数等の表示機能を設けても良い。
【００６６】
本発明の電池は様々な機器に使用される。特に、ビデオムービー、モニター内蔵携帯型ビデオデッキ、モニター内蔵ムービーカメラ、コンパクトカメラ、一眼レフカメラ、レンズ付きフィルム、ノート型パソコン、ノート型ワープロ、電子手帳、携帯電話、コードレス電話、ヒゲソリ、電動工具、電動ミキサー、自動車等に使用されることが好ましい。
【００６７】
【実施例】
以下に具体例をあげ、本発明をさらに詳しく説明するが、発明の主旨を越えない限り、本発明は実施例に限定されるものではない。
【００６８】
実施例−１
〔正極合剤ペーストの作成〕
正極活物質；ＬｉＣｏＯ₂（炭酸リチウムと四酸化三コバルトと３：２のモル比で混合したものをアルミナるつぼにいれ、空気中、毎分２℃で７５０℃に昇温し４時間仮焼した後、さらに毎分２℃の速度で９００℃に昇温しその温度で８時間焼成し解砕したもの。中心粒子サイズ５μｍ、洗浄品５０ｇを１００ｍｌの水に分散した時の分散液の電導度は０．６ｍＳ／ｍ、ｐＨは１０．１、窒素吸着法による比表面積は０．４２ｍ² ／ｇ）を２００ｇとアセチレンブラック１０ｇとを、ホモジナイザーで混合し、続いて結着剤として２−エチルヘキシルアクリレートとアクリル酸とアクリロニトリルの共重合体の水分散物（固形分濃度５０重量％）を８ｇ、濃度２重量％のカルボキシメチルセルロース水溶液を６０ｇを加え混練混合し、さらに水を５０ｇを加え、ホモジナイザーで攪拌混合し、正極合剤ペーストを作成した。
【００６９】
〔負極合剤ペーストの作成〕
負極活物質；ＳｎＧｅ_0.1 Ｂ_0.5 Ｐ_0.58Ｍｇ_0.1 Ｋ_0.1 Ｏ_3.35（一酸化錫６．７ｇ、ピロリン酸錫１０．３ｇ、三酸化二硼素１．７ｇ、炭酸カリウム０．７ｇ、酸化マグネシウム０．４ｇ、二酸化ゲルマニウム１．０ｇを乾式混合し、アルミナ製るつぼに入れ、アルゴン雰囲気下１５℃／分で１０００℃まで昇温し、１１００℃で１２時間焼成した後、１０℃／分で室温にまで降温し焼成炉より取り出したものを集め、ジェットミルで粉砕したもの、平均粒径４．５μm、ＣｕＫα線を用いたＸ線回折法において２θ値で２８°付近に頂点を有するブロードなピークを有する物であり、２θ値で４０°以上７０°以下には結晶性の回折線は見られなかった。）を２００ｇ、導電剤（人造黒鉛）３０ｇとホモジナイザーで混合し、さらに結着剤として濃度２重量％のカルボキシメチルセルロース水溶液５０ｇ、ポリフッ化ビニリデン１０ｇとを加え混合したものと水を３０ｇ加えさらに混練混合し、負極合剤ペーストを作成した。
【００７０】
〔正極および負極電極シートの作成〕
上記で作成した正極合剤ペーストをブレードコーターで厚さ３０μｍのアルミニウム箔集電体の両面に、塗布量４００ｇ／ｍ² 、圧縮後のシートの厚みが２８０μｍになるように塗布し、乾燥した後、ローラープレス機で圧縮成型し所定の大きさに裁断し、帯状の正極シートを作成した。さらにドライボックス（露点；−５０℃以下の乾燥空気）中で遠赤外線ヒーターにて充分脱水乾燥し、正極シートを作成した。
同様に、負極合剤ペーストを２０μｍの銅箔集電体に塗布し、上記正極シート作成と同様の方法で、塗布量７０ｇ／ｍ² 、圧縮後のシートの厚みが９０μｍである負極シートを作成した。
〔電解液調製〕
アルゴン雰囲気で、２００ｃｃの細口のポリプロピレン容器に６５．３ｇの炭酸ジエチルをいれ、これに液温が３０℃を越えないように注意しながら、２２．２ｇの炭酸エチレンを少量ずつ溶解した。次に、０．４ｇのＬｉＢＦ₄ ，１２．１ｇのＬｉＰＦ₆ を液温が３０℃を越えないように注意しながら、それぞれ順番に、上記ポリプロピレン容器に少量ずつ溶解した。得られた電解液は比重１．１３５で無色透明の液体であった。水分は１８ｐｐｍ（京都電子製 商品名ＭＫＣ−２１０型カールフィシャー水分測定装置で測定）、遊離酸分は２４ｐｐｍ（ブロムチモールブルーを指示薬とし、０．１規定ＮａＯＨ水溶液を用いて中和滴定して測定）であった。さらにこの電解液に表２に記載の化合物を所定濃度になるようにそれぞれ溶解させ電解液１から１６を調製した。
【００７１】
【表２】

【００７２】
〔シリンダー電池の作成〕
正極シート、微孔性ポリプロピレンフィルム製セパレーター、負極シートおよびセパレーターの順に積層し、これを渦巻き状に巻回した。この巻回体を負極端子を兼ねるニッケルメッキを施した鉄製の有底円筒型電池缶に収納したものを１２個用意した。各々の電池缶内に電解液１から１６をそれぞれ注入し、正極端子を有する電池蓋をガスケットを介してかしめて円筒型電池（１−１から１−１６）を作成した。
【００７３】
実施例−２
負極活物質として黒鉛粉末を用いる以外は実施例−１と同様の方法で円筒型電池（電池番号２−１から２−１２）を作成した。
【００７４】
上記の方法で作成した電池について、電流密度４．９ｍＡ／ｃｍ² 、充電終止電圧４．１Ｖ、放電終止電圧２．８Ｖの条件で充放電を繰り返し、各サイクルにおける放電容量を求めた。
表３、および表４にはそれぞれの電池の相対容量（１サイクルめの放電容量を電池１−１２の値で規格化）、およびサイクル性（１サイクルめの放電容量に対する３００サイクルめの放電容量の割合）を示した。
【００７５】
【表３】

【００７６】
【表４】

【００７７】
本発明の添加剤を添加した場合、スズ系負極、炭素系負極のいずれの場合でも容量の低下を引き起こす事なくサイクル性を向上する事がわかる。一方比較化合物Ａ、ＢおよびＣを添加した場合はサイクル性は向上するものの無視できない程度の容量低下がみられる。比較化合物Ｄを添加した場合は容量低下はないものの、サイクル性改良効果が小さい。よって本発明の化合物を用いた方が有利である。
また、本発明の添加剤を用いない時、スズ系負極を使用した電池は炭素系負極を使用した電池よりも容量が高いがサイクル性が悪い。しかし本発明の化合物を用いるとスズ系負極を使用した電池は炭素負極に対し容量が大きくサイクル性は劣っていない。よって本発明の化合物とスズ系負極を組み合わせるのが最も有利である。
本発明の化合物の添加量の効果を見ると添加濃度が０．０１モル／リットルの場合が容量、サイクル性のいずれをとっても好ましい。
【００７８】
【発明の効果】
本発明の添加剤を用いれば容量が高く、充放電繰り返しによる放電容量の低下の少ない非水電解液二次電池を得ることができる。
【図面の簡単な説明】
【図１】実施例に使用したシリンダー型電池の断面図を示す。
【符号の説明】
１ ポリプロピレン製ガスケット
２ 負極端子を兼ねる負極缶（電池缶）
３ セパレーター
４ 負極シート
５ 正極シート
６ 非水電解液
７ 防爆弁体
８ 正極端子を兼ねる正極キャップ
９ ＰＴＣ素子
１０ 内部フタ体
１１ リング[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous electrolyte secondary battery having high voltage, high capacity, and excellent charge / discharge cycle characteristics.
[0002]
[Prior art]
A non-aqueous electrolyte secondary battery using lithium (lithium secondary battery) is a positive and negative electrode containing a material capable of reversibly occluding and releasing lithium, a non-aqueous electrolyte containing a lithium salt, and appropriately holding these, Consists of isolation members. Since lithium is lightweight and has a very low potential, lithium secondary batteries have excellent characteristics of high voltage and high capacity. In particular, when an oxide or chalcogen compound mainly composed of Sn is used for the negative electrode material, the amount of lithium occluded increases dramatically, and an excellent secondary battery having an extremely high capacity can be obtained. However, this battery has a problem in that the capacity decreases when charging and discharging are repeated over a long period of time.
Needless to say, the smaller the degree of reduction in capacity when charging / discharging is repeated over a long period of time (the better the cycleability) is, the better the practical battery, and the improvement of cycleability is one of the biggest problems for lithium secondary battery manufacturers. It has become one.
Japanese Patent Application Laid-Open Nos. 6-84523, 84524, and 333595 disclose a technique for improving the cycle performance by preventing the decomposition of an organic solvent in an electrolyte by adding amines. Although the amines disclosed in these patents are effective in improving the cycle performance, there is a drawback that the capacity decreases.
Japanese Patent Application Laid-Open No. 5-234618 discloses a technique that suppresses the deposition of metallic lithium on the negative electrode and improves the cycleability by adding a compound having a coordination group to lithium to the electrolyte. ing. However, it is difficult to say that the effect of improving the cycle performance by this technique is sufficient, and further improvement has been desired.
[0003]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to improve the cycle performance without impairing the characteristics of a lithium secondary battery having high voltage and high capacity characteristics.
[0004]
[Means for Solving the Problems]
An object of the present invention is to provide a nonaqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte containing a lithium salt, and the oxidation potential in the battery is in the range of +3.8 V or more and +4.3 V or less with respect to lithium. A non-aqueous electrolyte secondary battery characterized by containing a certain compound has been solved.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Although the preferable form of this invention is demonstrated below, this invention is not limited to these.
(1) In a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte containing a lithium salt, a compound having an oxidation potential in the range of +3.8 V or more and +4.3 V or less with respect to lithium is contained in the battery. A non-aqueous electrolyte secondary battery characterized by containing.
(2) The non-reactor according to item 1, wherein the compound having an oxidation potential in the range of +3.8 V or more and +4.3 V or less with respect to lithium is a compound represented by the following general formula (1): Water electrolyte secondary battery.
General formula (1) R1-X-R2
In the general formula (1), R1 represents an aryl group or a heterocyclic residue, R2 represents an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, or a heterocyclic residue, and X represents an oxygen atom or a sulfur atom. . However, when X is an oxygen atom, R1 is an aryl group substituted with an electron donating group. R1 and R2 may combine with each other to form a ring.
(3) The non-aqueous electrolyte secondary battery according to item 2, wherein the compound represented by the general formula (1) in item 2 is a compound represented by the following general formula (2).
Formula (2) R21- (X-R22) n
In general formula (2), R21 represents a divalent to hexavalent residue obtained by removing any 2 to 6 hydrogen atoms from an aromatic hydrocarbon, R22 represents a group having the same meaning as R2 in general formula (1), and X represents An oxygen atom or a sulfur atom, n represents an integer of 2 to 6 corresponding to R21. Two X-R22 bonded to R21 may be bonded to each other to form a ring. (4) The nonaqueous electrolysis according to item 1, wherein the nonaqueous electrolytic solution containing a lithium salt contains the compound having an oxidation potential in the range of +3.8 V or more and +4.3 V or less with respect to lithium. Liquid secondary battery.
(5) The amount of the compound contained in the non-aqueous electrolyte and having an oxidation potential in the range of +3.8 V or more and +4.3 V or less with respect to lithium is 0.1 mmol or more and 50 mmol or less. Item 5. The nonaqueous electrolyte secondary battery according to Item 4.
(6) The negative electrode has a negative electrode material capable of inserting and extracting lithium ions, and the negative electrode material is mainly amorphous containing three or more kinds of atoms selected from Group 1, 2, 13, 14, and 15 atoms of the periodic table. Item 6. The nonaqueous electrolyte secondary battery according to any one of Items 1 to 5, which is a chalcogen compound or an amorphous oxide.
(7) The nonaqueous electrolyte secondary battery according to item 6, wherein the anode material capable of inserting and extracting lithium ions is mainly an amorphous chalcogen compound or oxide mainly composed of Sn.
(8) The nonaqueous electrolyte secondary battery according to item 7, wherein the negative electrode material mainly composed of Sn is an amorphous oxide represented by the general formula (3).
General formula (3) SnM^Three _cM^Four _dO_t
(Where M^ThreeIs at least one element selected from Al, B, P, Ge, Si, M^FourRepresents at least one element selected from Group 1 elements, Group 2 elements, Group 3 elements and halogen elements in the periodic table, c is a number from 0.2 to 2, and d is from 0.01 to 1. In the following numbers, 0.2 <c + d <2, t represents a number from 1 to 6. )
[0006]
In the present inventors, the deterioration factor of the cycle property is that the organic solvent in the electrolyte is oxidatively decomposed on the positive electrode, and the decomposed product is gradually deposited on the positive electrode to inhibit a desirable electrochemical reaction inside the battery. I guessed it. As a result of adding various reducing compounds as additives to the electrolytic solution for the purpose of preventing oxidative decomposition and investigating the effects, reducing agents having favorable properties (improve cycle performance without reducing capacity) Have been found to be compounds having a specific chemical structure, both of which have an oxidation potential within an appropriate range, and have led to the present invention.
The appropriate range of the oxidation potential is in the range of +3.8 V to +4.3 V, more preferably +3.9 to +4.2 V, with metallic lithium as the reference electrode. In the following description, a compound having an appropriate oxidation potential in the present invention is simply referred to as a reducing agent of the present invention.
[0007]
In general, when the oxidation potential of the reducing agent is higher than this appropriate range, there is no cycle improvement effect, and when it is low, the capacity tends to decrease. These phenomena are estimated as follows.
Although the potential of the positive electrode gradually increases due to charging, the potential on the surface of the positive electrode is not necessarily uniform, and a minute portion (overvoltage portion) having an excessively high potential is generated. In the overvoltage portion, strong oxidizing species such as active oxygen can be generated. For this reason, it is estimated that the oxidative decomposition of the organic solvent in the electrolyte occurs at this overvoltage portion. At this time, if an additive having a preferable potential (appropriate reducing property) is present, the additive is preferentially oxidized to prevent decomposition of the organic solvent. And the oxidant of this additive partly adheres to the positive electrode, and part of it diffuses to reach the negative electrode. The oxidant adhering to the positive electrode is reduced and returned to the original when the positive electrode potential decreases during discharge, and the oxidant that has reached the negative electrode is reduced and returned to the original on the negative electrode. The latter reaction is a leak and leads to a decrease in capacity, but if it is infrequent, there is no practical problem.
It is considered that an additive having an oxidation potential that is too high (having a weak reducing power) is not necessarily preferentially oxidized and cannot sufficiently prevent the decomposition of the organic solvent. In addition, since the additive having an oxidation potential that is too low (strong reducing power) is oxidized on the positive electrode surface other than the overvoltage portion, the frequency of leakage will increase and capacity reduction will be a problem.
[0008]
Examples of the additive having the preferred oxidation potential described above include compounds represented by the following general formula (1).
General formula (1) R1-X-R2
In the general formula (1), R1 represents an aryl group or a heterocyclic residue, R2 represents an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, or an aryl group, and X represents an oxygen atom or a sulfur atom. R1 and R2 may combine with each other to form a ring.
[0009]
Next, the compound represented by the general formula (1) will be described in more detail. In the general formula (1), R1, R2, and X are selected so that the oxidation potential of the compound of the general formula (1) falls within the appropriate range described above. R1 is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms (phenyl group, naphthyl group, anthryl group, etc.), or a substituted or unsubstituted heterocyclic residue having 3 to 24 carbon atoms (pyridyl group, quinolyl group). Group, imidazolyl group, indazolyl group, furyl group, thienyl group, thiadiazolyl group, benzoxazolyl group, benzothiazolyl group, benzimidazolyl group, 2-thiazolinyl group and the like. Among these, an aryl group is preferable, and an aryl group substituted with at least one electron donating group is particularly preferable. The electron donating group here refers to those having a Hammett's sigma value of less than 0. Hammett's sigma value is widely recognized in organic chemistry, and many references are known, for example, Naoki Inamoto's “Hammett's Law” (Maruzen). Examples of preferable electron donating groups are alkyl groups (methyl group, ethyl group, butyl group, dodecyl group, cyclohexyl group, etc.), hydroxy groups, alkoxy groups (methoxy group, ethoxy group, dodecyloxy group, benzyloxy group, etc.), Aryloxy groups (such as phenoxy groups), mercapto groups, alkylthio groups (such as methylthio groups, butylthio groups, benzylthio groups), arylthio groups (such as phenylthio groups, naphthylthio groups), amino groups (amino groups, anilino groups, methylamino groups, Dimethylamino group, dibutylamino group, etc.).
[0010]
R2 represents a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms (such as a methyl group, ethyl group, butyl group, dodecyl group, and cyclohexyl group), and a substituted or unsubstituted alkenyl group having 2 to 24 carbon atoms (vinyl). Group, allyl group, 1-decen-10-yl group, cyclopentadienyl group, etc.), substituted or unsubstituted alkynyl groups having 2 to 24 carbon atoms (ethynyl group, propargyl group, 1-ethynylcyclohexyl group, etc.) A substituted or unsubstituted aralkyl group having 7 to 24 carbon atoms (such as benzyl group, diphenylmethyl group or naphthylmethyl group), or a substituted or unsubstituted aryl group having 6 to 24 carbon atoms (such as a phenyl group or naphthyl group). , Anthryl group and the like. Of these, an alkyl group, an aralkyl group, and an aryl group are preferable.
[0011]
The substituent for substituting the compound of the general formula (1) is an alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group, hydroxy group, alkoxy group (for example, methoxy group, ethoxy group, dodecyloxy group, benzyloxy group, etc.) ), Aryloxy groups (for example, phenoxy groups), mercapto groups, alkylthio groups (for example, methylthio groups, butylthio groups, benzylthio groups), arylthio groups (for example, phenylthio groups, naphthylthio groups, etc.), amino groups (for example, amino groups, anilino groups) Group, methylamino group, dimethylamino group, dibutylamino group, etc.), cyano group, amide group (eg acetylamino group, benzoylamino group etc.), sulfonamide group (eg methanesulfonylamino group, benzenesulfonylamino group etc.), Ureido group, ester (For example, acetoxy group, benzoyloxy group, methoxycarbonyl group, phenoxycarbonyl group, etc.), carbamoyl group (for example, N-methylcarbamoyl, N, N-diphenylcarbamoyl, etc.), sulfamoyl group (for example, N-phenylsulfamoyl, etc.), An acyl group (for example, acetyl, benzoyl, etc.), a sulfonyl group (for example, methanesulfonyl etc.), a carboxyl group, a sulfo group, etc. are mentioned.
[0012]
X represents an oxygen atom or a sulfur atom. However, when X is an oxygen atom, R1 must be an aryl group substituted with an electron donating group for adjusting the oxidation potential. In this case, an alkoxy group, an aryloxy group, or a hydroxy group is preferable as the electron donating group. R1 and R2 may be bonded to each other to form a ring.
[0013]
Of the compounds represented by the general formula (1), a compound represented by the following general formula (2) is particularly preferable.
Formula (2) R21- (X-R22) n
In the general formula (2), R21 represents a divalent to hexavalent residue obtained by removing any 2 to 6 hydrogen atoms from an aromatic hydrocarbon. R22 represents a group having the same meaning as R2 in formula (1), X represents an oxygen atom or a sulfur atom, and n represents an integer of 2 to 6 corresponding to R21. Two X-R22 bonded to R21 may be bonded to each other to form a ring.
Preferred aromatic hydrocarbons for R21 include benzene, naphthalene, anthracene, phenanthrene, triphenylene, biphenyl, pyrene, and the like. R22 is preferably a substituted or unsubstituted alkyl group or aryl group. n is preferably 2 to 4, and 2 is particularly preferable. The case where two X-R22 bonded to R21 are bonded to each other to form a ring includes the case where two R22 groups are bonded to form a benzene ring or a naphthalene ring.
[0014]
Next, although the specific example of a compound represented by General formula (1) is shown, this invention is not limited to these.
[0015]
[Chemical 1]

[0016]
[Chemical 2]

[0017]
[Chemical 3]

[0018]
[Formula 4]

[0019]
[Chemical formula 5]

[0020]
In many cases, the compound represented by the general formula (1) is commercially available as a reagent. Representative reagent manufacturers or agents include Wako Pure Chemical Industries, Ltd., Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan Co., Ltd. and the like. Hereinafter, a method for synthesizing a compound that cannot be obtained as a reagent will be described with specific examples, but the present invention is not limited thereto.
[0021]
Synthesis of exemplary compound (2)
21.7 g of thiodiphenol, 41 g of methyl paratoluenesulfonate, 200 ml of N, N-dimethylformamide, and 54 g of potassium carbonate were mixed and heated and stirred at 100 ° C. for 1 hour. Next, the reaction mixture was poured into water and the precipitated white solid was collected by filtration. The solid was dried and recrystallized with a mixed solvent of ethyl acetate-hexane to obtain 14 g of exemplary compound (2).
[0022]
Next, the oxidation potential will be described. The inventors measured the oxidation potential of the reducing agent by the following method. LiPF in a 20:80 mixture (weight ratio) of ethylene carbonate and diethyl carbonate₆Was dissolved to prepare a 1 mol / liter electrolyte. In 50 g of this electrolyte, 18 mg of the exemplary compound (1) of the present invention was dissolved, and 2 × 10^-3A mol / liter solution (Sample 1) was prepared. Next, Sample 11 to Sample 11 were prepared in the same manner except that the compound shown in Table 1 was used instead of the exemplified compound (1) of the present invention.
[0023]
Each sample was bubbled with argon gas, and then cyclic voltammetry was performed using a potentiostat HA-301 type and a function generator HB-104 type manufactured by Hokuto Denko. A metal lithium foil was used for the reference electrode, and a glassy carbon electrode was used for the working electrode. The potential was swept from + 3V to + 4.4V at a rate of 90 mV per second. In order to evaluate reducing agents that are not reversible in the same row, the value of the rising potential of the anode current (potential when a change in current of 5% with respect to the peak value of the anode current) is detected, not the half-wave potential. The oxidation potential (Eapp) was used.
[0024]
[Table 1]

[0025]
[Chemical 6]

[0026]
The relationship between the oxidation potential, the cycle improvement effect, and the capacity claimed by the present inventors will be shown in the examples described later.
[0027]
Next, the addition method and addition amount of a reducing agent will be described. In the present invention, the reducing agent may be added to any of the positive electrode, the negative electrode, and the electrolyte, but it is preferably added to the positive electrode or the electrolyte in view of the presumed action mechanism, and particularly preferably added to the electrolytic solution.
[0028]
The addition amount can be arbitrarily selected, but the concentration when added to the electrolytic solution is preferably 0.1 mmol / liter or more and 50 mmol / liter or less. 1 mmol / liter or more and 30 mmol / liter or less is particularly preferable.
When added to the positive electrode, it is preferably 0.01 weight percent or more, 5 weight percent or less, or 0.1 weight percent or more, and more preferably 2 weight percent or less with respect to the positive electrode active material.
[0029]
Hereinafter, the manufacturing method of the nonaqueous electrolyte secondary battery of the present invention will be described.
In the nonaqueous electrolyte secondary battery of the present invention, a positive and negative electrode sheet wound with a separator (winding group) is inserted into a battery can, the can and the electrode are electrically connected, and the electrolyte is injected. Create after sealing. Moreover, various members (a sealing plate, a lead plate, a gasket, an exterior material, etc.) are used as needed.
[0030]
The positive (negative) electrode sheet can be prepared by applying a positive (negative) electrode mixture onto a current collector, drying, and compressing.
The mixture is prepared by mixing a positive electrode (or negative electrode) material and a conductive agent, adding a binder (suspension or emulsion of resin powder), and a dispersion medium, kneading and mixing, followed by a mixer, It can be carried out by dispersing with a stirring mixer or disperser such as a homogenizer, dissolver, planetary mixer, paint shaker or sand mill. As the dispersion medium, water or an organic solvent is used, but water is preferable. In addition, additives such as a filler, an ionic conductive agent, and a pressure enhancer may be added as appropriate.
Application can be performed by various methods, for example, reverse roll method, direct roll method, blade method, knife method, extrusion method, curtain method, gravure method, bar method, dipping method and squeeze method. I can do it. A blade method, a knife method and an extrusion method are preferred. The application is preferably performed at a speed of 0.1 to 100 m / min. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting the said application | coating method according to the liquid physical property of a mixture paste, and drying property. The thickness, length and width of the coating layer are determined by the size of the battery. The thickness of a typical coating layer is 10 to 1000 μm in a compressed state after drying.
The electrode sheet after application is dried and dehydrated by the action of hot air, vacuum, infrared rays, far infrared rays, electron beams and low-humidity air. These methods can be used alone or in combination. The drying temperature is preferably in the range of 80 to 350 ° C, particularly preferably in the range of 100 to 250 ° C. The water content after drying is preferably 2000 ppm or less, and more preferably 500 ppm or less.
For the compression of the electrode sheet, a generally employed pressing method can be used, but a die pressing method and a calendar pressing method are particularly preferable. The press pressure is not particularly limited, but is 10 kg / cm.²~ 3t / cm²Is preferred. The press speed of the calendar press method is preferably 0.1 to 50 m / min. The pressing temperature is preferably room temperature to 200 ° C.
[0031]
The positive electrode material used in the present invention is a lithium-containing transition metal oxide. Preferably, it is an oxide mainly containing at least one transition metal element selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W and lithium, and the molar ratio of lithium to transition metal is It is a compound of 0.3 to 2.2. More preferably, the oxide mainly contains at least one transition metal element selected from V, Cr, Mn, Fe, Co, and Ni and lithium, and the molar ratio of lithium to transition metal is 0.3 to 0.3. It is the compound of 2.2. In addition, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, or the like may be contained within a range of less than 30 mole percent with respect to the transition metal present mainly. More preferred lithium-containing transition metal oxides are Li_xCoO₂, Li_xNiO₂, Li_xMnO₂, Li_xCo_aNi_1-aO₂, Li_xCo_bV_1-bO_z, Li_xCo_bFe_1-bO₂, Li_xMn₂O_Four, Li_xMn_cCo_2-cO_Four, Li_xMn_cNi_2-cO_Four, Li_xMn_cV_2-cO_Four, Li_xMn_cFe_2-cO_Four(Where x = 0.02 to 1.2, a = 0.1 to 0.9, b = 0.8 to 0.98, c = 1.6 to 1.96, z = 2.1-2. .3).
The most preferred lithium-containing transition metal oxide is Li_xCoO₂, Li_xNiO₂, Li_xMnO₂, Li_xCo_aNi_1-aO₂, Li_xMn₂O_Four, Li_xCo_bV_1-bO_z(X = 0.02 to 1.2, a = 0.1 to 0.9, b = 0.9 to 0.98, z = 2.01 to 2.3). In addition, the value of x is a value before the start of charging / discharging, and increases / decreases by charging / discharging.
[0032]
The positive electrode active material used in the present invention can be synthesized by a method in which a lithium compound and a transition metal compound are mixed and fired, or by a solution reaction, and a firing method is particularly preferable.
Details for firing are described in paragraph 35 of JP-A-6-60,867, JP-A-7-14,579, and the like, and these methods can be used. The positive electrode active material obtained by firing may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
Further, as a method of chemically inserting lithium ions into the transition metal oxide, a method of synthesis by reacting lithium metal, a lithium alloy or butyl lithium with a transition metal oxide may be used.
[0033]
The average particle size of the positive electrode active material used in the present invention is not particularly limited, but is preferably 0.1 to 50 μm. The volume of particles of 0.5 to 30 μm is preferably 95% or more. More preferably, the volume occupied by a particle group having a particle size of 3 μm or less is 18% or less of the total volume, and the volume occupied by a particle group of 15 μm or more and 25 μm or less is 18% or less of the total volume. Although it does not specifically limit as a specific surface area, it is 0.01-50m in BET method²/ G is preferred, especially 0.2 m² / G-1m² / G is preferred. The pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.
[0034]
When the positive electrode active material of the present invention is obtained by firing, the firing temperature is preferably 500 to 1500 ° C, more preferably 700 to 1200 ° C, and particularly preferably 750 to 1000 ° C. The firing time is preferably 4 to 30 hours, more preferably 6 to 20 hours, and particularly preferably 6 to 15 hours.
[0035]
The negative electrode material used in the present invention may be a compound that can occlude and release lithium ions. Examples of such negative electrode materials include metallic lithium, lithium alloys, carbonaceous compounds, inorganic oxides, inorganic chalcogen compounds, metal complexes, and organic polymer compounds. These may be used alone or in combination.
[0036]
In the present invention, an amorphous chalcogen compound or an amorphous oxide mainly containing three or more kinds of atoms selected from periodic table 1, 2, 13, 14, and 15 group atoms is particularly preferably used as the negative electrode material. The term “amorphous” as used herein refers to an X-ray diffraction method using CuKα rays, which has a broad scattering band having an apex from 20 ° to 40 ° as a 2θ value, and has a crystalline diffraction line. Also good. Preferably, the strongest intensity of the crystalline diffraction lines seen at 2θ values of 40 ° or more and 70 ° or less is 500 of diffraction line intensities at the apexes of broad scattering bands seen at 2θ values of 20 ° or more and 40 ° or less. It is preferably not more than twice, more preferably not more than 100 times, particularly preferably not more than 5 times, and most preferably not having a crystalline diffraction line.
[0037]
The chalcogen compound and oxide are composite chalcogen compounds mainly composed of two or more elements of B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb and Bi, A composite oxide is more preferable. Particularly preferred are composite chalcogen compounds or oxides mainly composed of two or more elements of B, Al, Si, Ge, Sn, and P. These composite chalcogen compounds and composite oxides mainly contain at least one element selected from elements of Groups 1 to 2 of the periodic table in order to modify the amorphous structure.
[0038]
Among the above negative electrode materials, an amorphous composite oxide mainly composed of Sn is preferable, and is represented by the following general formula (3).
General formula (3) SnM^Three _cM^Four _dO_t
Where M^ThreeIs at least one of Al, B, P, Ge, M^FourRepresents at least one of group 1 element and group 2 element in the periodic table, c is a number of 0.2 or more and 2 or less, d is a number of 0.01 or more and 1 or less, and 0.2 <c + d <2, t represents a number from 1 to 6.
[0039]
The amorphous composite oxide of the present invention can employ either a firing method or a solution method, but a firing method is more preferable. In the firing method, it is preferable to obtain an amorphous composite oxide by thoroughly mixing oxides or compounds of the elements described in the general formula (1) and then firing.
[0040]
As firing conditions, the temperature rise rate is preferably 5 ° C. or more and 200 ° C. or less per minute, the firing temperature is preferably 500 ° C. or more and 1500 ° C. or less, and the firing time is 1 hour. It is preferable that it is 100 hours or less. In addition, the temperature decrease rate is 2 ° C. or more per minute and 10⁷ It is preferable that it is below ℃.
The rate of temperature increase in the present invention is the average rate of temperature rise from “50% of the firing temperature (indicated in ° C.)” to “80% of the firing temperature (indicated in ° C.)”. It is the average rate of temperature drop from reaching “80% of the firing temperature (indicated in degrees Celsius)” to “50% of the firing temperature (indicated in degrees Celsius)”.
The temperature lowering may be cooled in a firing furnace, or taken out of the firing furnace and cooled, for example, in water. In addition, a super rapid cooling method such as a gun method, a Hammer-Anvil method, a slap method, a gas atomization method, a plasma spray method, a centrifugal quenching method, or a melt drag method described on page 217 of ceramics processing (Gihodo Publishing 1987) can also be used. Moreover, you may cool using the single roller method and the double roller method of New Glass Handbook (Maruzen 1991) p.172. In the case of a material that melts during firing, the fired product may be continuously taken out while supplying raw materials during firing. In the case of a material that melts during firing, it is preferable to stir the melt.
[0041]
The firing gas atmosphere is preferably an atmosphere having an oxygen content of 5% by volume or less, and more preferably an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, helium, krypton, and xenon. The most preferred inert gas is pure argon.
[0042]
As for the average particle size of the compound shown by this invention, 0.1-60 micrometers is preferable. More specifically, it is preferable that the average particle diameter is 0.7 to 25 μm, and 60% or more of the total volume is 0.5 to 30 μm. The volume occupied by the particle group having a particle size of 1 μm or less of the negative electrode active material of the present invention is 30% or less of the total volume, and the volume occupied by the particle group having a particle size of 20 μm or more is 25% or less of the total volume. Is preferred. Needless to say, the particle size of the material used does not exceed the thickness of the mixture on one side of the negative electrode.
To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.
The average particle diameter is a median diameter of primary particles, and is measured by a laser diffraction type particle size distribution measuring apparatus.
[0043]
Although the example of the negative electrode material of this invention is shown below, this invention is not limited to these.
SnAl_0.4B_0.5P_0.5K_0.1O_3.65, SnAl_0.4B_0.5P_0.5Na_0.2O_3.7, SnAl_0.4B_0.3P_0.5Rb_0.2O_3.4, SnAl_0.4B_0.5P_0.5Cs_0.1O_3.65,
SnAl_0.4B_0.5P_0.5K_0.1Ge_0.05O_3.85, SnAl_0.4B_0.5P_0.5K_0.1Mg_0.1Ge_0.02O_3.83, SnAl_0.4B_0.4P_0.4O_3.2, SnAl_0.3B_0.5P_0.2O_2.7,
SnAl_0.3B_0.5P_0.2O_2.7, SnAl_0.4B_0.5P_0.3Ba_0.08Mg_0.08O_3.26, SnAl_0.4B_0.4P_0.4Ba_0.08O_3.28, SnAl_0.4B_0.5P_0.5O_3.6, SnAl_0.4B_0.5P_0.5Mg_0.1O_3.7
[0044]
SnAl_0.5B_0.4P_0.5Mg_0.1F_0.2O_3.65, SnB_0.5P_0.5Li_0.1Mg_0.1F_0.2O_3.05, SnB_0.5P_0.5K_0.1Mg_0.1F_0.2O_3.05, SnB_0.5P_0.5K_0.05Mg_0.05F_0.1O_3.03, SnB_0.5P_0.5K_0.05Mg_0.1F_0.2O_3.03, SnAl_0.4B_0.5P_0.5Cs_0.1Mg_0.1F_0.2O_3.65, SnB_0.5P_0.5Cs_0.05Mg_0.05F_0.1O_3.03, SnB_0.5P_0.5Mg_0.1F_0.1O_3.05, SnB_0.5P_0.5Mg_0.1F_0.2O_Three , SnB_0.5P_0.5Mg_0.1F_0.06O_3.07, SnB_0.5P_0.5Mg_0.1F_0.14O_3.03, SnPBa_0.08O_3.58, SnPK_0.1O_3.55, SnPK_0.05Mg_0.05O_3.58, SnPCs_0.1O_3.55, SnPBa_0.08F_0.08O_3.54, SnPK_0.1Mg_0.1F_0.2O_3.55, SnPK_0.05Mg_0.05F_0.1O_3.53, SnPCs_0.1Mg_0.1F_0.2O_3.55, SnPCs_0.05Mg_0.05F_0.1O_3.53,
[0045]
Sn_1.1Al_0.4B_0.2P_0.6Ba_0.08F_0.08O_3.54, Sn_1.1Al_0.4B_0.2P_0.6Li_0.1K_0.1Ba_0.1F_0.1O_3.65, Sn_1.1Al_0.4B_0.4P_0.4Ba_0.08O_3.34,
Sn_1.1Al_0.4PCs_0.05O_4.23, Sn_1.1Al_0.4PK_0.05O_4.23, Sn_1.2Al_0.5B_0.3P_0.4Cs_0.2O_3.5, Sn_1.2Al_0.4B_0.2P_0.6Ba_0.08O_3.68, Sn_1.2Al_0.4B_0.2P_0.6Ba_0.08F_0.08O_3.64, Sn_1.2Al_0.4B_0.2P_0.6Mg_0.04Ba_0.04O_3.68, Sn_1.2Al_0.4B_0.3P_0.5Ba_0.08O_3.58, Sn_1.3Al_0.3B_0.3P_0.4Na_0.2O_3.3, Sn_1.3Al_0.2B_0.4P_0.4Ca_0.2O_3.4, Sn_1.3Al_0.4B_0.4P_0.4Ba_0.2O_3.6, Sn_1.4Al_0.4PK_0.2O_4.6, Sn_1.4Al_0.2Ba_0.1PK_0.2O_4.45, Sn_1.4Al_0.2Ba_0.2PK_0.2O_4.6, Sn_1.4Al_0.4a_0.2PK_0.2Ba_0.1F_0.2O_4.9, Sn_1.4Al_0.4PK_0.3O_4.65, Sn_1.5Al_0.2PK_0.2O_4.4, Sn_1.5Al_0.4PK_0.1O_4.65, Sn_1.5Al_0.4PCs_0.05O_4.63, Sn_1.5Al_0.4PCs_0.05Mg_0.1F_0.24.63
[0046]
SnSi_0.5Al_0.1B_0.2P_0.1Ca_0.4O_3.1, SnSi_0.4Al_0.2B_{0. Four}O_2.7, SnSi_0.5Al_0.2B_0.1P_0.1Mg_0.1O_2.8, SnSi_0.6Al_0.2B_0.2O_2.8,
SnSi_0.5Al_0.3B_0.4P_0.2O_3.55, SnSi_0.5Al_0.3B_0.4P_0.5O_4.30, SnSi_0.6Al_0.1B_0.1P_0.3O_3.25, SnSi_0.6Al_0.1B_0.1P_0.1Ba_0.2O_2.95. SnSi_0.6Al_0.1B_0.1P_0.1Ca_0.2O_2.95, SnSi_0.6Al_0.4B_0.2Mg_0.1O_3.2, SnSi_0.6Al_0.1B_0.3P_0.1O_3.05, SnSi_0.6Al_0.2Mg_0.2O_2.7, SnSi_0.6Al_0.2Ca_0.2O_2.7, SnSi_0.6Al_0.2P_0.2O_Three,
SnSi_0.6B_0.2P_0.2O_Three , SnSi_0.8Al_0.2O_2.9, SnSi_0.8Al_0.3B_0.2P_0.2O_3.85, SnSi_0.8B_0.2O_2.9, SnSi_0.8Ba_0.2O_2.8, SnSi_0.8Mg_0.2O_2.8, SnSi_0.8Ca_0.2O_2.8, SnSi_0.8P_0.2O_3.1
[0047]
Sn_0.9Mn_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.9Fe_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.8Pb_0.2Ca_0.1P_0.9O_3.35, Sn_0.3Ge_0.7Ba_0.1P_0.9O_3.35, Sn_0.9Mn_0.1Mg_0.1P_0.9O_3.35, Sn_0.2Mn_0.8Mg_0.1P_0.9O_3.35, Sn_0.7Pb_0.3Ca_0.1P_0.9O_3.35, Sn_0.2Ge_0.8Ba_0.1P_0.9O_3.35.
[0048]
The chemical formula of the compound obtained by firing can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method and a weight difference between powders before and after firing as a simple method.
[0049]
The conductive agent used in the present invention may be anything as long as it is an electron conductive material that does not cause a chemical change in the constructed battery. Specific examples include natural graphite such as scaly graphite, scaly graphite and earthy graphite, high-temperature fired bodies such as petroleum coke, coal coke, celluloses, saccharides and mesophase pitch, and graphite such as artificial graphite such as vapor-grown graphite. , Carbon blacks such as acetylene black, furnace black, ketjen black, channel black, lamp black, thermal black, etc., carbon materials such as asphalt pitch, coal tar, activated carbon, mesofuse pitch, polyacene, conductivity of metal fibers, etc. Examples thereof include fibers, metal powders such as copper, nickel, aluminum and silver, conductive whiskers such as zinc oxide and potassium titanate, and conductive metal oxides such as titanium oxide. Of these, graphite and carbon black are preferred. These may be used singly or as a mixture.
The amount of the conductive agent added to the mixture layer is preferably 6 to 50% by weight, particularly 6 to 30% by weight, based on the negative electrode material or the positive electrode material. In the case of carbon black or graphite, the content is particularly preferably 6 to 20% by weight.
[0050]
In the present invention, a binder is used to hold the electrode mixture. Examples of the binder include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Preferred binders include starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium alginate, polyacrylic acid, polyacrylic acid Na, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone. Water-soluble polymers such as polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene furo Ride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene (Meth) acrylic acid ester copolymers containing (meth) acrylic acid esters such as ethylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, (meth) acrylic Acid ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluororubber, polyethylene oxide, polyester polyurethane Resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, phenol resin, epoxy resin emulsion (latex) or suspension It can be cited. In particular, polyacrylate ester latex, carboxymethyl cellulose, polytetrafluoroethylene, and polyvinylidene fluoride are exemplified.
These binders can be used alone or in combination. When the amount of the binder added is small, the holding power and cohesion of the electrode mixture is weak. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit weight decreases. For this reason, the addition amount of the binder is preferably 1 to 30% by weight, and particularly preferably 2 to 10% by weight.
[0051]
Any filler can be used as long as it is a fibrous material that does not cause a chemical change in the constructed battery. Usually, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0 to 30 weight% is preferable.
As the ionic conductive agent, those known as inorganic and organic solid electrolytes can be used, and details are described in the section of the electrolytic solution.
The pressure enhancer is a compound that increases the internal pressure of the battery, and carbonate is a typical example.
[0052]
In the current collector that can be used in the present invention, the positive electrode is aluminum, stainless steel, nickel, titanium, or an alloy thereof, and the negative electrode is copper, stainless steel, nickel, titanium, or an alloy thereof. The form of the current collector is foil, expanded metal, punching metal, or wire mesh. In particular, an aluminum foil is preferable for the positive electrode and a copper foil is preferable for the negative electrode.
[0053]
The separator that can be used in the present invention is only required to be an insulating thin film having a large ion permeability, a predetermined mechanical strength, and an olefin polymer, a fluorine polymer, a cellulose polymer, polyimide, nylon, Glass fiber and alumina fiber are used, and as a form, a nonwoven fabric, a woven fabric, and a microporous film are used. In particular, the material is preferably polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, or a mixture of polyethylene and Teflon, and the form is preferably a microporous film. In particular, a microporous film having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferable.
[0054]
The electrolytic solution is generally composed of a supporting salt and a solvent. Lithium salt is mainly used as the supporting salt in the lithium secondary battery.
Examples of lithium salts that can be used in the present invention include LiClO._Four, LiBF_Four, LiPF₆, LiCF_ThreeSO_Three, LiCF_ThreeCO₂, LiAsF₆, LiSbF₆, LiB_TenCl_Ten, Lower aliphatic lithium carboxylate, LiAlCl_Four Li salts such as LiCl, LiBr, LiI, chloroborane lithium and lithium tetraphenylborate can be raised, and these can be used alone or in combination. Above all, LiBF_FourAnd / or LiPF₆What melt | dissolved is preferable.
The concentration of the supporting salt is not particularly limited, but is preferably 0.2 to 3 mol per liter of the electrolytic solution.
[0055]
Solvents that can be used in the present invention include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, methyl formate, methyl acetate, 1,2-dimethoxy. Ethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, dioxane, acetonitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3 -Aprotic such as methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, 1,3-propane sultone Machine solvent can be cited, to use a mixture of alone or in combination. Among these, carbonate-based solvents are preferable, and it is particularly preferable to use a mixture of a cyclic carbonate and an acyclic carbonate. As the cyclic carbonate, ethylene carbonate and propylene carbonate are preferable. Moreover, as an acyclic carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate are preferable.
As an electrolytic solution that can be used in the present invention, LiCF is added to an electrolytic solution obtained by appropriately mixing ethylene carbonate, propylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate, or diethyl carbonate._ThreeSO_ThreeLiClO_Four, LiBF_FourAnd / or LiPF₆An electrolytic solution containing is preferable. In particular, in a mixed solvent of at least one of propylene carbonate or ethylene carbonate and at least one of dimethyl carbonate or diethyl carbonate, LiCF_ThreeSO_ThreeLiClO_FourOr LiBF_FourAt least one salt selected from the group consisting of LiPF and LiPF₆An electrolytic solution containing is preferable. The amount of the electrolyte added to the battery is not particularly limited, and can be used depending on the amount of the positive electrode material or the negative electrode material or the size of the battery.
[0056]
In addition to the electrolytic solution, the following solid electrolyte can be used in combination.
The solid electrolyte is classified into an inorganic solid electrolyte and an organic solid electrolyte.
Well-known inorganic solid electrolytes include Li nitrides, halides, oxyacid salts, and the like. Among them, Li_ThreeN, LiI, Li_FiveNI₂, Li_ThreeN-LiI-LiOH, Li_FourSiO_Four, Li_FourSiO_Four-LiI-LiOH, x Li_ThreePO_Four− (1-x) Li_FourSiO_Four, Li₂SiS_ThreeIn addition, phosphorus sulfide compounds are effective.
[0057]
In the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ion dissociation group, a mixture of a polymer containing an ion dissociation group and the above aprotic electrolyte, phosphoric acid A polymer matrix material containing an ester polymer and an aprotic polar solvent is effective. Furthermore, there is a method of adding polyacrylonitrile to the electrolytic solution. A method of using an inorganic and organic solid electrolyte in combination is also known.
[0058]
Further, other compounds may be added to the electrolyte for the purpose of improving discharge and charge / discharge characteristics. For example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone and N, N'-substituted imidazolidinone, ethylene glycol dialkyl ether , Quaternary ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol, AlCl_Three, Conductive polymer electrode active material monomers, triethylenephosphoramide, trialkylphosphine, morpholine, aryl compounds having a carbonyl group, crown ethers such as 12-crown-4, hexamethylphosphoric triamide and 4-alkyl Examples thereof include morpholine, bicyclic tertiary amine, oil, quaternary phosphonium salt, and tertiary sulfonium salt.
[0059]
In order to make the electrolyte nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolyte. In addition, carbon dioxide gas can be included in the electrolyte in order to make it suitable for high-temperature storage.
[0060]
The entire amount of the electrolytic solution may be injected once, but it is preferable to inject it in two or more times. When injecting in two or more times, each solution may have the same composition but a different composition (for example, a non-aqueous solvent or a non-aqueous solvent having a higher viscosity than the solvent after injecting a solution of a lithium salt in a non-aqueous solvent). Or a solution in which a lithium salt is dissolved in a solvent or a non-aqueous solvent may be injected). In order to shorten the time for injecting the electrolyte, etc., the battery can may be decompressed, or centrifugal force or ultrasonic waves may be applied to the battery can.
[0061]
Battery cans and battery lids that can be used in the present invention are nickel steel plated steel plates, stainless steel plates (SUS304, SUS304L, SUS304N, SUS316, SUS316L, SUS430, SUS444, etc.), nickel plated stainless steel plates (same as above) , Aluminum or an alloy thereof, nickel, titanium, and copper, and the shapes are a true circular cylinder, an elliptical cylinder, a square cylinder, and a rectangular cylinder. In particular, when the outer can also serves as the negative electrode terminal, a stainless steel plate and a nickel-plated steel plate are preferable, and when the outer can also serves as the positive electrode terminal, a stainless steel plate, aluminum, or an alloy thereof is preferable. The shape of the battery can may be any of buttons, coins, sheets, cylinders, and corners.
A safety valve can be used for the sealing plate as a countermeasure against an increase in the internal pressure of the battery can. In addition, a method of cutting a member such as a battery can or a gasket can be used. In addition, various conventionally known safety elements (for example, fuses, bimetals, PTC elements, etc. as overcurrent prevention elements) may be provided.
[0062]
For the lead plate used in the present invention, a metal having electrical conductivity (for example, iron, nickel, titanium, chromium, molybdenum, copper, aluminum, etc.) or an alloy thereof can be used. As a welding method for the battery lid, battery can, electrode sheet, and lead plate, a known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.
[0063]
Gaskets that can be used in the present invention are olefin polymers, fluoropolymers, cellulose polymers, polyimides, and polyamides as materials. Olefin polymers are preferred from the viewpoint of organic solvent resistance and low moisture permeability, and are mainly composed of propylene. Polymers are preferred. Furthermore, a block copolymer of propylene and ethylene is preferable.
[0064]
The battery of the present invention is covered with an exterior material as necessary. Examples of the exterior material include a heat-shrinkable tube, an adhesive tape, a metal film, paper, cloth, paint, and a plastic case. Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be known.
[0065]
A plurality of the batteries of the present invention are assembled in series and / or in parallel as needed, and stored in a battery pack. In addition to safety elements such as positive temperature coefficient resistors, temperature fuses, fuses and / or current interrupting elements, the battery pack also requires safety circuits (monitoring the voltage, temperature, current, etc. of each battery and / or the entire battery pack) In this case, a circuit having a function of interrupting current may be provided. In addition to the positive and negative terminals of the entire assembled battery, the battery pack should be provided with the positive and negative terminals of each battery, the entire assembled battery, the temperature detection terminal of each battery, the current detection terminal of the entire assembled battery, etc. as external terminals. You can also. The battery pack may incorporate a voltage conversion circuit (such as a DC-DC converter). The connection of each battery may be fixed by welding a lead plate, or may be fixed so that it can be easily attached and detached with a socket or the like. Further, the battery pack may be provided with display functions such as the remaining battery capacity, the presence / absence of charging, and the number of uses.
[0066]
The battery of the present invention is used in various devices. In particular, video movies, portable video decks with built-in monitors, movie cameras with built-in monitors, compact cameras, single-lens reflex cameras, film with lenses, notebook computers, notebook word processors, electronic notebooks, mobile phones, cordless phones, shavings, power tools, It is preferably used for electric mixers, automobiles and the like.
[0067]
【Example】
Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.
[0068]
Example-1
[Creation of positive electrode mixture paste]
Cathode active material; LiCoO₂(A mixture of lithium carbonate and tricobalt tetroxide in a molar ratio of 3: 2 is placed in an alumina crucible, heated to 750 ° C. at 2 ° C./min in the air, calcined for 4 hours, and then 2 min / min. The temperature was raised to 900 ° C. at a rate of 0 ° C., baked and pulverized at that temperature for 8 hours, and the electrical conductivity of the dispersion liquid was 0.6 mS / m when the center particle size was 5 μm and the washing product was dispersed in 100 ml of water , PH is 10.1, specific surface area by nitrogen adsorption method is 0.42m²/ G) 200 g and acetylene black 10 g were mixed with a homogenizer, and subsequently 8 g of an aqueous dispersion of a copolymer of 2-ethylhexyl acrylate, acrylic acid and acrylonitrile (solid content concentration 50% by weight) was used as a binder. 60 g of a carboxymethyl cellulose aqueous solution having a concentration of 2% by weight was added and kneaded and mixed, 50 g of water was further added, and the mixture was stirred and mixed with a homogenizer to prepare a positive electrode mixture paste.
[0069]
[Creation of negative electrode mixture paste]
Negative electrode active material; SnGe_0.1B_0.5P_0.58Mg_0.1K_0.1O_3.35(6.7 g of tin monoxide, 10.3 g of tin pyrophosphate, 1.7 g of diboron trioxide, 0.7 g of potassium carbonate, 0.4 g of magnesium oxide, and 1.0 g of germanium dioxide were dry-mixed and placed in an alumina crucible. The temperature was raised to 1000 ° C. at 15 ° C./min in an argon atmosphere, baked at 1100 ° C. for 12 hours, cooled to room temperature at 10 ° C./min, collected from the baking furnace, and pulverized with a jet mill In the X-ray diffraction method using an average particle size of 4.5 μm and CuKα ray, the material has a broad peak having a peak at around 28 ° with a 2θ value, and the crystallinity at a 2θ value of 40 ° to 70 ° Was mixed with 200 g of a conductive agent (artificial graphite) with a homogenizer, and 50 g of a 2% by weight carboxymethylcellulose aqueous solution as a binder. What the water added and mixed with vinylidene fluoride 10g mixed further kneaded added 30g, created the negative electrode material mixture paste.
[0070]
[Creation of positive and negative electrode sheets]
The positive electrode mixture paste prepared above was applied to both sides of a 30 μm thick aluminum foil current collector with a blade coater at a coating amount of 400 g / m.²Then, the coated sheet was applied so that the thickness of the compressed sheet was 280 μm, dried, and then compression-molded with a roller press machine and cut into a predetermined size to prepare a belt-like positive electrode sheet. Furthermore, it was sufficiently dehydrated and dried with a far-infrared heater in a dry box (dew point: dry air of −50 ° C. or lower) to prepare a positive electrode sheet.
Similarly, the negative electrode mixture paste was applied to a 20 μm copper foil current collector, and the application amount was 70 g / m in the same manner as in the positive electrode sheet preparation.²A negative electrode sheet having a thickness of 90 μm after compression was prepared.
(Electrolyte preparation)
In an argon atmosphere, 65.3 g of diethyl carbonate was placed in a 200 cc narrow-necked polypropylene container, and 22.2 g of ethylene carbonate was dissolved little by little while taking care that the liquid temperature did not exceed 30 ° C. Next, 0.4 g of LiBF_Four, 12.1 g LiPF₆The solution was dissolved in a small amount in the polypropylene container in order, taking care that the liquid temperature did not exceed 30 ° C. The obtained electrolyte was a colorless and transparent liquid with a specific gravity of 1.135. Moisture was 18ppm (measured with Kyoto Electronics, trade name: MKC-210, Karl Fischer moisture analyzer), free acid content was 24ppm (measured by neutralization titration with 0.1N NaOH aqueous solution using bromthymol blue as an indicator) )Met. Furthermore, each of the compounds shown in Table 2 was dissolved in the electrolytic solution to a predetermined concentration to prepare electrolytic solutions 1 to 16.
[0071]
[Table 2]

[0072]
[Creation of cylinder battery]
A positive electrode sheet, a microporous polypropylene film separator, a negative electrode sheet and a separator were laminated in this order, and this was wound in a spiral shape. Twelve of these wound bodies were prepared by storing them in iron-bottomed cylindrical battery cans plated with nickel that also serve as negative electrode terminals. Electrolytic solutions 1 to 16 were respectively injected into each battery can, and a battery lid having a positive electrode terminal was crimped through a gasket to prepare cylindrical batteries (1-1 to 1-16).
[0073]
Example-2
Cylindrical batteries (battery numbers 2-1 to 2-12) were prepared in the same manner as in Example 1 except that graphite powder was used as the negative electrode active material.
[0074]
For the battery prepared by the above method, the current density is 4.9 mA / cm.²Then, charge and discharge were repeated under the conditions of a charge end voltage of 4.1 V and a discharge end voltage of 2.8 V, and the discharge capacity in each cycle was determined.
Tables 3 and 4 show the relative capacity of each battery (the discharge capacity at the first cycle is normalized by the value of the battery 1-12) and the cycle characteristics (the discharge capacity at the 300th cycle relative to the discharge capacity at the first cycle). Ratio).
[0075]
[Table 3]

[0076]
[Table 4]

[0077]
It can be seen that when the additive of the present invention is added, the cycle performance is improved without causing a decrease in capacity in both the tin-based negative electrode and the carbon-based negative electrode. On the other hand, when the comparative compounds A, B and C are added, the cycle performance is improved, but a capacity decrease that cannot be ignored is observed. When Comparative Compound D is added, the capacity is not reduced, but the effect of improving the cycleability is small. Therefore, it is advantageous to use the compound of the present invention.
In addition, when the additive of the present invention is not used, a battery using a tin-based negative electrode has a higher capacity than a battery using a carbon-based negative electrode, but poor cycleability. However, when the compound of the present invention is used, a battery using a tin-based negative electrode has a capacity larger than that of the carbon negative electrode and is not inferior in cycle performance. Therefore, it is most advantageous to combine the compound of the present invention with a tin-based negative electrode.
In view of the effect of the addition amount of the compound of the present invention, it is preferable that the addition concentration is 0.01 mol / liter in terms of both capacity and cycleability.
[0078]
【The invention's effect】
By using the additive of the present invention, it is possible to obtain a non-aqueous electrolyte secondary battery that has a high capacity and has little reduction in discharge capacity due to repeated charge and discharge.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a cylinder type battery used in Examples.
[Explanation of symbols]
1 Polypropylene gasket
2 Negative electrode can (battery can) that also serves as the negative electrode terminal
3 Separator
4 Negative electrode sheet
5 Positive electrode sheet
6 Non-aqueous electrolyte
7 Explosion-proof valve body
8 Positive cap that doubles as positive terminal
9 PTC element
10 Internal lid
11 rings

Claims (4)

In a non-aqueous electrolyte containing a cyclic carbonate, an acyclic carbonate and a lithium salt,
The lithium salt includes at least one salt selected from LiCF ₃ SO ₃ , LiClO ₄ , or LiBF ₄ and LiPF ₆ , and an oxidation potential in a range of +3.8 V or more and +4.3 V or less with respect to lithium. A nonaqueous electrolytic solution containing any one of the following compound Nos. 1 to 4 in an amount of 0.1 mmol to 50 mmol with respect to the electrolytic solution;
Diphenyl sulfide (Compound No. 1),
4,4′-dimethoxydiphenyl sulfide (Compound No. 2),
1,2-bis (4-methoxyphenylthio) ethane (Compound No. 3),
Thianthrene (Compound No. 4) . The cyclic carbonate contains at least one selected from ethylene carbonate and propylene carbonate;
The non-aqueous electrolyte according to claim 1, wherein the acyclic carbonate contains at least one selected from diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate. The lithium salt, non-aqueous electrolyte according to claim 1 or 2 LiBF is ₄ and LiPF _6. Into the container, a positive electrode, a negative electrode, and a non-rechargeable lithium battery aqueous electrolyte is filled according to any one of claims 1-3.

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