【発明の詳細な説明】[Detailed description of the invention]
産業上の利用分野
本発明はクラツド式鉛電池正極板（以下、クラ
ツド式正極板という）に関するものである。
従来の技術とその問題点
クラツド式正極板はガラス繊維や耐酸、耐酸化
性の合成繊維などからなる多孔性チユーブの中心
に鉛合金の芯金を配置した格子体の鉛粉を充填
し、ソーキング、化成等の工程を経て製造され
る。多孔性チユーブが活物質の脱落を防止するの
でペースト式正極板に比べて長寿命の正極板が得
られる。
微粉末である鉛粉のチユーブ内への充填は振動
を加えながら行なう。振動の程度が不充分なとき
はチユーブ内に鉛粉が詰つていない空洞部分が生
じるので、チユーブ内のすみずみまで鉛粉を充填
したときの密度は当然は高くなる。そのため活物
質の密度も高くなり、正極活物質利用を向上させ
ることは困難であつた。また仮にチユーブ内に空
洞を生じることなく低い充填密度で鉛粉を充填で
きたとしても、鉛粉粒子間の結合が充分でないた
めに、化成が進みにくく、正極活物質利用率も低
いものとなる。さらに鉛粉を充填する際に有害物
質である鉛粉塵が発生し、作業環境上も好ましく
ない。そこで鉛粉を充填する代りに鉛粉を水また
は希硫酸で混練したスラリー状のペーストを充填
する方法が考えられている。ところが、ペースト
が硬すぎると充填そのものが困難であるし、無理
に充填するとチユーブが破損するなどのトラブル
が生じる。充填が容易なスラリー状のペーストと
するには、鉛粉と混練する水または希硫酸の量を
かなり多くする必要がある。しかしペースト密度
が低くなるために、一定容積のチユーブに充填で
きる正極活物質量が必然的に小くなつてしまい、
鉛粉を充填する従来のクラツド式極板に比較する
と、正極活物質利用率の向上が期待できても極板
もの絶対容量とくに低率放電容量が不足するとい
う欠点があつた。
問題点を解決するための手段
本発明は上記の欠点を除去し、性能の優れたク
ラツド式正極板を提供するもので、その骨子とす
るところは正極ペーストにリグニンと異方性の大
なる黒鉛を添加することにある。リグニンはセメ
ントの凝結遅延剤としても利用されているよう
に、通常ではチユーブに充填できないような硬い
ペーストでも、リグニンを添加するというチユー
ブ内への充填が容易な硬さのスラリーが得られ
る。一方、異方性の大なる黒鉛は陽極酸化を受け
る膨張して導電性の高い安定な黒鉛層間化合物に
なり、正極活物質の導電性を高めるとともにその
構造を変化させて、放電に際しては活物質利用率
の向上に寄与するものである。
実施例
以下、本発明の実施例について説明する。
通常の鉛粉に粒径100〜1200μｍの異方性の大
なる黒鉛を1.0wt％と水に可溶性の市販のリグニ
ンを0.2〜0.5wt％添加してよく混合した後水を加
えて混練した。ここでペーストの密度を変えるた
めに水の量を変化させた。ついで乾燥状態での
PbSO4が15wt％となるように一定量の希硫酸を
加えて混練した。こうして調製したスラリー状の
ペーストをチユーブ径９mmφのクラツド式格子体
（高さ10cm×幅10cm）に充填し、40℃で24時間熟
成を行つた後通常の鉛合金格子を負極として比重
1.05の希硫酸中で化成した。化成後の極板は流水
中で３時間水洗し、50℃の気流中で24時間乾燥し
た。得られた化成および乾燥済みのクラツド式正
極板は容量の充分大きな負極板と組合せて、正極
板１枚、負極板２枚の構成の試験電池を作成し
た。ついで初充電を行ない、電解液比重を1.26に
調製して10時間率放電および30分間率放電を行な
い、鉛粉を充填した従来品と比較した結果を次表
に示す。
INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a positive electrode plate for a clad lead-acid battery (hereinafter referred to as a clad positive electrode plate). Conventional technology and its problems The clad type positive electrode plate is a porous tube made of glass fiber, acid-resistant, oxidation-resistant synthetic fiber, etc., filled with lead powder in a lattice with a lead alloy core placed in the center, and soaked. It is manufactured through processes such as , chemical conversion, etc. Since the porous tube prevents the active material from falling off, a positive electrode plate with a longer life than a paste-type positive electrode plate can be obtained. The fine lead powder is filled into the tube while being vibrated. When the degree of vibration is insufficient, a hollow portion is created in the tube that is not filled with lead powder, so naturally the density will be higher when the tube is filled with lead powder to every corner. Therefore, the density of the active material also increases, making it difficult to improve the utilization of the positive electrode active material. Furthermore, even if it were possible to fill the tube with lead powder at a low packing density without creating cavities, the bonding between the lead powder particles would be insufficient, making it difficult for chemical formation to proceed, and the utilization rate of the positive electrode active material would be low. . Furthermore, when filling with lead powder, lead dust, which is a harmful substance, is generated, which is not favorable for the working environment. Therefore, instead of filling with lead powder, a method of filling with a slurry paste made by kneading lead powder with water or dilute sulfuric acid has been considered. However, if the paste is too hard, it will be difficult to fill it, and if the paste is forcibly filled, problems such as damage to the tube will occur. In order to obtain a slurry-like paste that is easy to fill, it is necessary to increase the amount of water or dilute sulfuric acid mixed with the lead powder. However, as the paste density decreases, the amount of positive electrode active material that can be filled into a tube with a certain volume inevitably becomes smaller.
Compared to the conventional clad-type electrode plate filled with lead powder, although an improvement in the utilization rate of the positive electrode active material can be expected, the problem is that the absolute capacity of the electrode plate, especially the low rate discharge capacity, is insufficient. Means for Solving the Problems The present invention eliminates the above-mentioned drawbacks and provides a clad type positive electrode plate with excellent performance. The purpose is to add Lignin is also used as a setting retarder in cement, and even with hard pastes that would normally not be able to be filled into tubes, by adding lignin, a slurry with a hardness that can be easily filled into tubes can be obtained. On the other hand, highly anisotropic graphite undergoes anodic oxidation and expands to become a highly conductive and stable graphite intercalation compound, which increases the conductivity of the positive electrode active material and changes its structure. This contributes to improving utilization rates. Examples Examples of the present invention will be described below. 1.0 wt % of highly anisotropic graphite with a particle size of 100 to 1200 μm and 0.2 to 0.5 wt % of water-soluble commercially available lignin were added to ordinary lead powder, and after mixing well, water was added and kneaded. Here, the amount of water was varied to change the density of the paste. Then in a dry state
A certain amount of dilute sulfuric acid was added and kneaded so that PbSO 4 was 15 wt%. The slurry-like paste prepared in this way was filled into a clad lattice body (height 10 cm x width 10 cm) with a tube diameter of 9 mmφ, and after aging at 40°C for 24 hours, a normal lead alloy lattice was used as a negative electrode.
It was chemically formed in 1.05 dilute sulfuric acid. After chemical formation, the electrode plate was washed under running water for 3 hours and dried in an air stream at 50°C for 24 hours. The chemically formed and dried clad type positive electrode plate thus obtained was combined with a negative electrode plate having a sufficiently large capacity to prepare a test battery having one positive electrode plate and two negative electrode plates. Next, an initial charge was performed, the specific gravity of the electrolyte was adjusted to 1.26, and a 10-hour rate discharge and a 30-minute rate discharge were performed, and the results compared with a conventional product filled with lead powder are shown in the table below.
【表】
ここで記号Ａ〜Ｈの試験電池はスラリー状ペー
ストを充填したもの、Ｉは鉛粉を充填した従来品
である。なお、比較のために黒鉛を添加しない場
合についても同様の方法で正極板を作製して試験
に供した。鉛粉を水と希硫酸だけでスラリーを調
整する場合は、記号Ｇ，Ｈの2.9ｇ／cm3が限度で
あつて、これ以上のペースト密度ではスラリーが
硬すぎるため充填が不可能であつた。しかし、鉛
粉にリグニンを添加すると、スラリーが柔らかく
なり、ペースト密度3.5ｇ／cm3でも充填できた。
リグニンの添加量を増せばさらに高いペースト密
度でも充填が可能であつたが、鉛粉を充填した従
来品と匹敵する性能を出すためにはこの程度で充
分であつた。10時間率放電試験の結果ではペース
ト密度を上げるためにリグニンを添加し、かつ放
電性能を向上させるために異方性の大なる黒鉛を
添加したＡ，Ｂ，Ｃの各電池が放電容量の点でも
また正極活物質利用率においても従来品Ｉの性能
を上回つた。しかし、ペースト密度の低いＧやリ
グニンを添加してペースト密度を高めても異方性
の大なる黒鉛を添加しないＤ，Ｅ，Ｆでは従来品
Ｉと同等以下の放電容量であつた。30分間率放電
性能はいずれも従来品を上回つた。
発明の効果
以上詳述したように本発明によればクラツド式
電池の放電性能の向上が可能となり、また、極板
製造工程での鉛粉塵が発生しないなどの利点を有
し、工業上の価値は大きい。[Table] Here, test batteries with symbols A to H are those filled with slurry paste, and I is a conventional product filled with lead powder. For comparison, a positive electrode plate was prepared in the same manner and tested without adding graphite. When preparing a slurry of lead powder with only water and dilute sulfuric acid, the limit is 2.9 g/cm 3 with symbols G and H, and if the paste density was higher than this, the slurry would be too hard and filling would be impossible. . However, when lignin was added to the lead powder, the slurry became soft and filling was possible even at a paste density of 3.5 g/cm 3 .
Although it would have been possible to fill the paste at even higher paste densities by increasing the amount of lignin added, this level was sufficient to achieve performance comparable to conventional products filled with lead powder. The results of the 10-hour rate discharge test showed that batteries A, B, and C, in which lignin was added to increase paste density and highly anisotropic graphite was added to improve discharge performance, had the highest discharge capacity. However, it also exceeded the performance of conventional product I in terms of the utilization rate of the positive electrode active material. However, even if the paste density was increased by adding G or lignin, which has a low paste density, in D, E, and F, in which graphite with large anisotropy was not added, the discharge capacity was equal to or lower than that of conventional product I. The 30-minute rate discharge performance of both products exceeded that of conventional products. Effects of the Invention As detailed above, according to the present invention, it is possible to improve the discharge performance of a closed-loop battery, and it also has advantages such as not generating lead dust during the electrode plate manufacturing process, and has industrial value. is big.