JPH0346952B2

JPH0346952B2 -

Info

Publication number: JPH0346952B2
Application number: JP59074664A
Authority: JP
Inventors: Masakazu Takemura; Tsukane Ito; Tokuyuki Myazaki
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1984-04-12
Filing date: 1984-04-12
Publication date: 1991-07-17
Also published as: JPS60218773A

Description

[Detailed description of the invention]

(イ) 産業上の利用分野本発明はペースト式カドミウム極板を陰極と
し、水酸化ナトリウムに水酸化リチウムを添加し
たアルカリ電解液を有する密閉型アルカリ蓄電池
に関する。 (ロ) 従来技術従来から密閉型アルカリ蓄電池は特開昭50−
86638号公報に示される様に水酸化ナトリウムを
主体として水酸化リチウムが添加された電解液を
用ることで低温充放電特性を余り低下させること
なく高温特性を著しく改善させることができるこ
とが見いだされており、また、セパレータに関し
ては高温下に於いてアルカリ電解液と接すると共
に充電の際に陽極から発生する酸素ガスにさらさ
れるため耐酸化性耐アルカリ性に優れたポリプロ
ピレン繊維のセパレータを用いることにより高温
特性が改善されることが特開昭57−96459号公報
により知られている。しかしながら、上述の電解液及びセパレータを
用いて密閉型アルカリ蓄電池を構成した場合であ
つても、密閉型の電池は陽極から発生する酸素ガ
スを陰極で吸収させるために電解液を減少させる
ことで酸素ガス吸収能力を向上させる必要があ
り、その上セパレータとして用いるポリプロピレ
ン繊維が撥水性であるため陰、陽極間の電解液量
が不足気味となり充分な電池性能が得られない。また、ペースト式陰極板は焼結式極板のように
活物質層内に焼結金属による導電マトリツクスを
持たず、その活物質層の主成分である酸化カドミ
ウムの電子伝導性が低いため、充電の際に生成す
る金属カドミウムは導電性芯体の付近に偏在し、
過充電によつて陽極から発生する酸素ガスと接触
し易い陰極板表面に金属カドミウムが生成され難
いので、金属カドミウムと酸素ガスとが反応する
ことにより酸素ガスを消失させる酸素ガス吸収性
能が劣る。更に上述した構成の密閉型アルカリ蓄電池を高
温下に於いて長期連続充電を行なつた場合には、
陰極板の劣化より早く電池部品である封口ガスケ
ツトが劣化して電解液の漏出が起こり電池性能の
低下が生じるという問題がある。 (ハ) 発明の目的本発明はかかる点に鑑み高温下に於ける使用で
の構成部品の劣化を防止するとともに電解液不足
を抑制することにより電池性能の向上した密閉型
アルカリ蓄電池を提供せしめんとするものであ
る。 (ニ) 発明の構成本発明の密閉型アルカリ蓄電池は、導電芯体に
塗着形成した酸化カドミウムを主体とする活物質
層の表面に電解液と接してゲル状となる水溶性糊
料を結着剤として用いた炭素粉末よりなる導電層
を有するペースト式カドミウム陰極と、陽極と、
該陰陽極間に介在するポリプロピレン繊維セパレ
ータと、水酸化ナトリウムを主成分とし水酸化リ
チウムが添加された電解液とから構成されると共
に、電池ケースを封口する際に用いるガスケツト
にポリサルホン樹脂を用いたものであり、前記電
解液に５〜６規定の水酸化ナトリウムに１〜２規
定の水酸化リチウムを添加したものを用い、その
電解液の添加量を電池公称容量1AHあたり3.5〜
4.1mlとすることでより電池性能を向上させるこ
とができるものである。 (ホ) 実施例本発明の実施例を以下に示し比較例との対比に
言及する。実施例酸化カドミウムを主成分とし糊料剤と補強材を
含有するペーストを導電芯体に塗着し、厚み0.70
mmの未化成のペースト式カドミウム極板を作成
し、この極板の表面にアセチレンブラツク５重量
部、ポリビニルアルコール５重量部、水100重量
部からなるカーボンスラリーを夫々片面0.01mmの
厚さに塗布、乾燥した後圧延して厚さ0.68mmの陰
極板を得た。このカドミウム陰極板と公知のニツ
ケル陽極板をポリプロピレン不織布セパレータを
介して巻回し、電池ケースに挿入した後水酸化ナ
トリウムが５規定であり水酸化リチウムが２規定
である電解液を注入し、ポリサルホン製封口ガス
ケツトを用いて電池ケースの開口部を封口して公
称容量1.2AHの電池を作製した。こうして作製し
た電池を注入した電解液量により、下表のように
夫々Ａ−１乃至Ａ−６とする。尚電解液量は公称
容量1AHあたりの注液量を示している。 (a) Field of Industrial Application The present invention relates to a sealed alkaline storage battery having a paste-type cadmium electrode plate as a cathode and an alkaline electrolyte containing sodium hydroxide and lithium hydroxide. (b) Conventional technology Sealed alkaline storage batteries have been developed since 1973.
As shown in Publication No. 86638, it has been found that by using an electrolytic solution consisting mainly of sodium hydroxide and to which lithium hydroxide is added, high-temperature characteristics can be significantly improved without significantly deteriorating low-temperature charge-discharge characteristics. In addition, since the separator comes into contact with alkaline electrolyte at high temperatures and is exposed to oxygen gas generated from the anode during charging, we use polypropylene fiber separators with excellent oxidation and alkali resistance to withstand high temperatures. It is known from JP-A-57-96459 that the characteristics are improved. However, even when a sealed alkaline storage battery is constructed using the electrolyte and separator described above, the sealed battery requires oxygen gas to be absorbed by the cathode by reducing the amount of electrolyte generated from the anode. It is necessary to improve the gas absorption ability, and in addition, since the polypropylene fiber used as the separator is water repellent, the amount of electrolyte between the anode and the anode tends to be insufficient, making it difficult to obtain sufficient battery performance. In addition, paste-type cathode plates do not have a conductive matrix made of sintered metal in the active material layer like sintered-type electrode plates, and because cadmium oxide, the main component of the active material layer, has low electronic conductivity, charging The metallic cadmium produced during this process is unevenly distributed near the conductive core,
Since metal cadmium is difficult to be generated on the surface of the cathode plate, which is likely to come into contact with oxygen gas generated from the anode due to overcharging, the oxygen gas absorption performance, which eliminates oxygen gas by the reaction between metal cadmium and oxygen gas, is poor. Furthermore, when a sealed alkaline storage battery with the above configuration is continuously charged for a long period of time at high temperatures,
There is a problem in that the sealing gasket, which is a battery component, deteriorates faster than the cathode plate, causing leakage of electrolyte and deterioration of battery performance. (c) Purpose of the Invention In view of the above, the present invention aims to provide a sealed alkaline storage battery that improves battery performance by preventing deterioration of component parts when used at high temperatures and suppressing electrolyte shortage. That is. (d) Structure of the Invention The sealed alkaline storage battery of the present invention includes a water-soluble glue that forms a gel when in contact with an electrolytic solution on the surface of an active material layer mainly composed of cadmium oxide that is applied and formed on a conductive core. A paste-type cadmium cathode having a conductive layer made of carbon powder used as an adhesive, an anode,
It is composed of a polypropylene fiber separator interposed between the cathode and anode, and an electrolyte containing sodium hydroxide as a main component and lithium hydroxide added, and a polysulfone resin is used for the gasket used to seal the battery case. The electrolytic solution is 5-6N sodium hydroxide with 1-2N lithium hydroxide added, and the amount of the electrolyte added is 3.5-6N per 1AH of battery nominal capacity.
By setting the volume to 4.1ml, battery performance can be further improved. (e) Examples Examples of the present invention will be shown below and comparisons with comparative examples will be mentioned. Example: A paste containing cadmium oxide as a main component and a sizing agent and reinforcing material is applied to a conductive core to a thickness of 0.70.
An unformed paste-type cadmium electrode plate of 1.5 mm in size was prepared, and a carbon slurry consisting of 5 parts by weight of acetylene black, 5 parts by weight of polyvinyl alcohol, and 100 parts by weight of water was applied to the surface of this electrode plate to a thickness of 0.01 mm on each side. , dried and rolled to obtain a cathode plate with a thickness of 0.68 mm. This cadmium cathode plate and a known nickel anode plate are wound together with a polypropylene non-woven fabric separator interposed between them, and after inserting them into a battery case, an electrolytic solution containing 5N sodium hydroxide and 2N lithium hydroxide is injected, and a polysulfone A battery with a nominal capacity of 1.2 AH was fabricated by sealing the opening of the battery case using a sealing gasket. Depending on the amount of electrolyte injected into the battery thus produced, the batteries are designated as A-1 to A-6, respectively, as shown in the table below. The amount of electrolyte indicated is the amount of injected liquid per nominal capacity of 1 AH.

【表】比較例１前記実施例に於いて、陰極板をカーボン塗布を
施こさない未化成のペースト式カドミウム陰極板
に、セパレータをナイロンとポリプロピレン繊維
が１対１で混合したナイロン−ポリプロピレン混
合セパレータに、また、封口ガスケツトをナイロ
ン封口ガスケツトに夫々かえて用い、その他の条
件は同一で電解液の注入量が3.2ml／AHである電
池を作製した。この電池をＢとする。比較例２前記実施例に於いて、セパレータを前記ナイロ
ン−ポリプロピレン混合セパレータにかえて用
い、その他の条件は同一で電解液の注入量が4.0
ml／AHである電池を作製した。この電池をＣと
する。比較例３前記実施例に於いて、封口体をナイロン封口ガ
スケツトにかえて用い、その他の条件は同一で電
解液の注入量が4.0ml／AHである電池を作製し
た。この電池をＤとする。第１図は電池Ａ−２，Ａ−３，Ａ−５，Ａ−６
及びＢを夫々0°以下に於いて0.1C電流（Ｃは公称
容量を表わす）で連続充電を行なつたときの電池
内部ガス圧を示す図面である。一般に低温になる
程陰極板の酸素ガス吸収能力は低下し最悪の場合
には安全弁からリークする程電池内部ガス圧が上
昇することがあるため連続充電をする際には特に
電解液量を制限する必要があるが、第１図から明
らかな様に本発明電池は電解液量の増加に伴ない
電池内部ガスの上昇がみられるものの比較電池Ｂ
に比較して電解液量をかなり増加させても電池内
部ガス圧を低く抑えられることがわかる。これは
ペースト式カドミウム陰極板の表面に設けたカー
ボン層に影響されるものであり、比較電池の陰極
板では電子伝導性の低い水酸化カドミウムが導電
芯体近傍からしだいに充電状態の電子伝導性の良
好な金属カドミウムに変化して行くが充電部分が
ほとんど極板表面に達していても僅かに未充電状
態の水酸化カドミウムが表面に薄層となつて残つ
ている場合が多いため陽極から発生する酸素ガス
と接触する金属カドミウムが少なく酸素ガス吸収
能力が低いが、これに対して本発明の陰極板は導
電芯体を中心として生成する金属カドミウムがあ
る部分で陰極板表面のカーボン層まで到達する
と、導電芯体とカーボン層が電気的に接続された
状態になるため、活物質層内に未充電状態の水酸
化カドミウムを残したまま優先的に極板表面近傍
に金属カドミウムが生成されて酸素ガス吸収能力
が高められたからと考えられる。また第２図は電池Ａ−１，Ａ−２，Ａ−５及び
Ｂを夫々45°C下に於いてＣ／30電流で１ケ月充電
を行なつた後1C電流で放電するという条件でサ
イクル試験を行なつたときの電池の初期容量に対
する容量比を示す図面であり、本発明電池は何れ
も比較電池Ｂよりサイクルの経過による電池容量
比の減少が少なく良好となつている。この電池性
能の向上は、本発明電池が何れも前述した陰極板
表面のカーボン層により酸素ガス吸収能力が向上
しているため電解液量を多くすることができ、こ
の電解液量の増加のおかげで電池反応を向上せし
められたことに大きく関係しており、またカーボ
ン層形成に用いられた水溶性糊料であるポリビニ
ルアルコールが電解液と接してゲル状となり陰、
陽極間の電解液保持量を増加することができたこ
とにも起因すると考えられる。更に、この水溶性
糊料の存在により、本発明電池の陰極板はその表
面からの活物質及びカーボン粉末の脱落が完全に
防止できるため、従来の陰極板のような活物質粉
末の脱落による作業環境の悪化及び陰極容量の減
少をなくすことが可能である。尚、電解液量は
3.3ml／AH以上あると電池容量のバラツキが小さ
くなり良好であつた。第３図は電池Ａ−４、Ｃ及びＤを夫々前記サイ
クル試験と同一条件で充放電したときの電池の初
期容量に対する容量比を示す図面であり、本発明
電池は比較電池Ｃ及びＤと同一の陰極板及び同一
量の電解液を保有しているにもかかわらずこれら
比較電池より充放電サイクルの経過に伴う電池容
量比の減少が低く抑えられ優れた性能を有してい
ることがわかる。このことから本発明電池の性能
は前述した陰極板の構造及び電解液量の増加の他
にセパレータや封口ガスケツトの組成の違いにも
関係しより優れた電池であることがわかる。以上の様に本発明電池は陰極板、電解液、セパ
レータ及び封口ガスケツトが夫々電池性能の向上
に寄与して優れた性能を生み出したものである。
また電解液量については電池内部ガス圧及び電池
容量比を総合的に考慮すると3.2ml／AHでは電池
内部ガス圧の上昇が大き過ぎ、4.4ml／AHでは充
放電サイクルの経過に伴う電池容量比の減少が大
きいため3.5ml／AH〜4.1ml／AHが最適量であ
る。 (ヘ) 発明の効果本発明の密閉型アルカリ蓄電池は、導電芯体に
塗着形成した酸化カドミウムを主体とする活物質
層の表面に電解液と接してゲル状となる水溶性糊
料を結着剤として用いた炭素粉末よりなる導電層
を有するペースト式カドミウム陰極と、陽極と、
該陰陽極間に介在するポリプロピレン繊維セパレ
ータと、水酸化ナトリウムを主成分とし水酸化リ
チウムが添加された電解液とから構成されると共
に、電池ケースを封口する際に用いるガスケツト
にポリサルホン樹脂を用いたものであるから、低
温及び高温下で使用した場合に於いて電池内部ガ
ス圧を低く抑えることができると共に充放電サイ
クルの経過に伴う電池容量比の減少を低く抑える
ことができる優れた性能を持つた電池であり、電
解液量を3.5ml／AH〜4.1ml／AHとすることで最
も良好な電池性能を持つことが可能となるもので
ある。[Table] Comparative Example 1 In the above example, the cathode plate was an unformed paste-type cadmium cathode plate without carbon coating, and the separator was a nylon-polypropylene mixed separator made of a 1:1 mixture of nylon and polypropylene fibers. In addition, a battery was produced in which the sealing gasket was replaced with a nylon sealing gasket, the other conditions were the same, and the amount of electrolyte injected was 3.2 ml/AH. This battery is called B. Comparative Example 2 In the above example, the separator was replaced with the nylon-polypropylene mixed separator, other conditions were the same, and the injection amount of electrolyte was 4.0.
A battery with ml/AH was fabricated. This battery is called C. Comparative Example 3 A battery was produced in which the sealing body was replaced with a nylon sealing gasket in the previous example, the other conditions were the same, and the amount of electrolyte injected was 4.0 ml/AH. This battery is designated as D. Figure 1 shows batteries A-2, A-3, A-5, and A-6.
This is a graph showing the internal gas pressure of the battery when continuous charging is carried out with a current of 0.1C (C represents the nominal capacity) at 0° or below. In general, the oxygen gas absorption capacity of the cathode plate decreases as the temperature decreases, and in the worst case, the internal gas pressure of the battery may rise to the point where it leaks from the safety valve, so the amount of electrolyte should be especially limited when continuously charging. However, as is clear from Figure 1, in the battery of the present invention, the gas inside the battery increases as the amount of electrolyte increases, but compared to comparative battery B.
It can be seen that the internal gas pressure of the battery can be kept low even if the amount of electrolyte is increased considerably compared to the above. This is influenced by the carbon layer provided on the surface of the paste-type cadmium cathode plate, and in the cathode plate of the comparative battery, cadmium hydroxide, which has low electron conductivity, gradually becomes more conductive in the charged state from the vicinity of the conductive core. However, even if most of the charged part reaches the surface of the electrode plate, a thin layer of uncharged cadmium hydroxide often remains on the surface, so it is generated from the anode. However, in the cathode plate of the present invention, metal cadmium generated around the conductive core reaches the carbon layer on the surface of the cathode plate. Then, the conductive core and the carbon layer become electrically connected, so metallic cadmium is preferentially generated near the electrode plate surface while leaving uncharged cadmium hydroxide in the active material layer. This is thought to be due to the increased ability to absorb oxygen gas. Figure 2 shows batteries A-1, A-2, A-5 and B each being cycled under the conditions of charging at C/30 current for one month at 45°C and then discharging at 1C current. 2 is a diagram showing the capacity ratio to the initial capacity of the battery when tested, and all of the batteries of the present invention are better than Comparative Battery B, with less decrease in battery capacity ratio over the course of the cycle. This improvement in battery performance is due to the improved oxygen gas absorption ability of the batteries of the present invention due to the aforementioned carbon layer on the surface of the cathode plate, which allows for a larger amount of electrolyte. This is largely related to the improvement of battery reaction in the carbon layer, and polyvinyl alcohol, which is a water-soluble glue used to form the carbon layer, turns into a gel when it comes into contact with the electrolyte, causing a negative reaction.
This is also thought to be due to the fact that the amount of electrolyte held between the anodes could be increased. Furthermore, due to the presence of this water-soluble glue, the cathode plate of the battery of the present invention can completely prevent the active material and carbon powder from falling off from its surface, so that it is possible to completely prevent the active material powder and carbon powder from falling off from the surface of the cathode plate of the battery of the present invention. It is possible to eliminate environmental deterioration and reduction in cathode capacity. In addition, the amount of electrolyte is
When it was 3.3 ml/AH or more, the variation in battery capacity was small and it was good. FIG. 3 is a diagram showing the capacity ratio to the initial capacity of the batteries when batteries A-4, C, and D were charged and discharged under the same conditions as in the cycle test, and the batteries of the present invention are the same as comparative batteries C and D. Despite having the same amount of cathode plate and the same amount of electrolyte, it can be seen that the decrease in battery capacity ratio over the course of charge/discharge cycles is suppressed to a lower level than these comparative batteries, and the battery has superior performance. From this, it can be seen that the performance of the battery of the present invention is related not only to the structure of the cathode plate and the increase in the amount of electrolyte described above, but also to the difference in the composition of the separator and the sealing gasket, resulting in a superior battery. As described above, in the battery of the present invention, the cathode plate, electrolyte, separator, and sealing gasket each contribute to improving the battery performance, resulting in excellent performance.
Regarding the amount of electrolyte, considering the battery internal gas pressure and battery capacity ratio comprehensively, at 3.2ml/AH, the increase in battery internal gas pressure is too large, and at 4.4ml/AH, the battery capacity ratio increases as the charge/discharge cycle progresses. The optimum amount is 3.5ml/AH to 4.1ml/AH since the decrease in the amount is large. (F) Effects of the Invention The sealed alkaline storage battery of the present invention has a water-soluble glue that forms a gel when it comes into contact with an electrolytic solution on the surface of an active material layer mainly composed of cadmium oxide that is applied and formed on a conductive core. A paste-type cadmium cathode having a conductive layer made of carbon powder used as an adhesive, an anode,
It is composed of a polypropylene fiber separator interposed between the cathode and anode, and an electrolyte containing sodium hydroxide as a main component and lithium hydroxide added, and a polysulfone resin is used for the gasket used to seal the battery case. Because it is a battery, it has excellent performance that can keep the internal gas pressure of the battery low when used at low and high temperatures, and can also keep the decrease in battery capacity ratio low as the charge/discharge cycle progresses. The best battery performance can be achieved by setting the amount of electrolyte to 3.5 ml/AH to 4.1 ml/AH.

[Brief explanation of drawings]

第１図は充電時間と電池内部ガス圧との関係を
示す図面、第２図及び第３図はサイクル数と容量
比との関係を示す図面である。Ａ−１，Ａ−２，Ａ−３，Ａ−４，Ａ−５，Ａ
−６……本発明電池、Ｂ，Ｃ，Ｄ……比較電池。 FIG. 1 is a diagram showing the relationship between charging time and battery internal gas pressure, and FIGS. 2 and 3 are diagrams showing the relationship between cycle number and capacity ratio. A-1, A-2, A-3, A-4, A-5, A
-6...Battery of the present invention, B, C, D...Comparison batteries.

Claims

[Claims] 1. Carbon powder using as a binder a water-soluble glue that becomes gel-like when in contact with an electrolyte on the surface of an active material layer mainly composed of cadmium oxide that is applied and formed on a conductive core. It is composed of a paste-type cadmium cathode having a conductive layer, an anode, a polypropylene fiber separator interposed between the cathode and anode, and an electrolyte mainly composed of sodium hydroxide and to which lithium hydroxide is added. A sealed alkaline storage battery characterized by using polysulfone resin for the gasket used to seal the case. 2. The electrolytic solution is a mixture of 5-6 N sodium hydroxide with 1-2 N lithium hydroxide added, and the amount of the electrolyte is 3.5 N per 1 AH of battery nominal capacity.
The sealed alkaline storage battery according to claim 1, which has a volume of 4.1 ml.