JP4186197B2

JP4186197B2 - Positive electrode plate for lead acid battery

Info

Publication number: JP4186197B2
Application number: JP08766497A
Authority: JP
Inventors: 雅彦小斉; 祥二安川
Original assignee: GS Yuasa Corp
Current assignee: GS Yuasa Corp
Priority date: 1997-03-19
Filing date: 1997-03-19
Publication date: 2008-11-26
Anticipated expiration: 2017-03-19
Also published as: JPH10270028A

Description

【０００１】
【発明の属する技術分野】
本発明は鉛蓄電池用正極板の改良に関するものである。
【０００２】
【従来の技術】
現在、鉛蓄電池は自動車用や産業用をはじめとしてあらゆる分野で用いられている。その中で自動車用電池は最も需要が高く、軽量化、コストダウン化、メンテナンスフリー化、長寿命化、品質の安定化が求められている。
【０００３】
現在、鉛蓄電池に用いられている格子合金は鉛−アンチモン系と鉛−カルシウム−錫系（以後、鉛−カルシウム系と呼ぶ）に大別でき、鉛蓄電池の特性はこれらの格子合金によって著しく異なることが知られている。すなわち、鉛−アンチモン系合金の正極格子を用いた鉛蓄電池は深い充放電サイクルに優れた特性を示すが、自己放電が大きい欠点がある。一方、鉛−カルシウム系合金の正極格子を用いた鉛蓄電池は自己放電が少ない、使用中の減液が少ないため補水の必要がないなどのメンテナンスフリー特性に優れているものの、充放電サイクルを繰り返すと比較的早期に放電容量が低下することがあるという欠点がある。
【０００４】
一般に鉛蓄電池の容量低下は、充放電サイクル中に正極活物質粒子が粗大化して粒子間の接合性が低下するために起ることが知られている。この現象は活物質の軟化と呼ばれ、特に極板表面の活物質層から起こり、次第に内部の活物質へ拡大していくことが知られている。また、活物質の軟化は正極格子合金中のアンチモンが少なくなるほど起こりやすく、アンチモンが正極活物質の劣化に何らかの影響をおよぼしているものと考えられている。
【０００５】
従来、鉛蓄電池はつぎのように製造されている。すなわち、鉛合金製格子に、酸化度（一酸化鉛の重量％）６０〜９５％の鉛粉を希硫酸でペースト状に練ったものを充填し、熟成および乾燥を施して未化成極板とする。これらを用いて組み立てた電池を正極活物質の理論電気量比２００〜４００％の電気量で電槽化成して充電済み電池とする。
【０００６】
【発明が解決しようとする課題】
特に鉛−カルシウム系合金を正極格子として用いたときなどに、上述した熟成工程を改良し、たとえば、高温高湿熟成を施すことによって未化成活物質中に四塩基性硫酸鉛を生成させる方法などが提案されている。
【０００７】
これまでの熟成生成物である三塩基性硫酸鉛に比べて四塩基性硫酸鉛の結晶は大きいことから、この方法によれば、四塩基性硫酸鉛の強固な骨格を保った二酸化鉛が化成時に形成されるために優れた寿命性能が得られるという利点がある。しかし、四塩基性硫酸鉛の粗大な結晶は化成性に劣り、すなわちその結晶内部まで二酸化鉛に化成されないことから、充分な初期性能が得られないという欠点がある。
【０００８】
【課題を解決するための手段】
本発明は上述したような問題点を解決するもので、正極活物質の全細孔体積の１５〜３５％が細孔直径５〜５０μｍであることを特徴とするものである。これにより、鉛蓄電池正極板の高容量化および長寿命化をはかるものである。
【０００９】
本発明による鉛蓄電池用正極板は、鉛粉と水と希硫酸との混練手順を調整することにより正極活物質の全細孔体積の１５〜３５％が細孔直径５〜５０μｍであるよう構成したこと特徴とし、さらには好ましくは、鉛粉と水とを混練してスラリーを形成する工程と、前記スラリーに希硫酸を加え所定時間放置後に混練して活物質ペーストを形成する工程と、前記活物質ペーストを鉛合金製格子に充填した後、熟成させることにより活物質中に四塩基性硫酸鉛の凝集部を有する未化成極板を得る工程と、前記未化成極板を化成する工程とを備えた製造方法で得られることを特徴とするものである。
【００１０】
【実施例】
以下、本発明を実施例に基づいて説明する。
【００１１】
ボールミル式鉛粉１００ｋｇと水１２リットルと比重１．４の希硫酸８リットルを混練して正極ペーストを作製した。混練手順としては、次の条件で行った。
【００１２】
まず、所定量の鉛粉および水を混練機に投入し、これらを５分間混練して均一なスラリーを得た。このスラリーに所定量の希硫酸を加えて混練し、希硫酸投入方法の異なる４種類のペーストを作製した。すなわち、〓１のペーストはスラリーを混練しながら全量の希硫酸を滴下投入し（滴下時間３０分間）、〓２のペーストはスラリーに全量の希硫酸を投入後１０分間混練し、〓３のペーストはスラリーに全量の希硫酸を投入し１０分間放置後に１０分間混練し、〓４のペーストはスラリーに全量の希硫酸を投入し３０分間放置後に１０分間混練した。
【００１３】
このように練膏方法を変えたのはペースト中の硫酸の分布を変えるためで、これらのペーストのなかで硫酸が最も均一に分布しているのは〓１のペーストで、次いで〓２、〓３、〓４の順に次第に不均一に分布し、すなわち硫酸の凝集部が大きくなっている。
【００１４】
これらの４種類のペーストを常法によって通常のＰｂ−Ｃａ−Ｓｎ合金を用いた鋳造格子に充填し、５０℃および７０℃の２種類の温度の熟成室中で２４時間熟成を施した。なお、熟成室中の相対湿度はいずれの温度においても１００％とした。熟成後の極板を５０℃乾燥室中（相対湿度２５％）で３日間乾燥し、表１に示す８種類の未化成正極板を得た。
【００１５】
【表１】

ここで用いた、極板の大きさは高さ１１０ｍｍ、幅１０８ｍｍ、厚さ２．０ｍｍで、化成後活物質密度は約3.8g/cm³となるようにした。これらの未化成正極板４枚／セルと、Ｐｂ−Ｃａ−Ｓｎ合金格子を用いた通常の未化成負極板５枚／セルとをリブ付ポリエチレンセパレータを介して積層し、ＪＩＳＤ５３０１に規定される自動車用鉛蓄電池３６Ｂ２０（５時間率容量：２８Ａｈ）を組み立てた。ついで、これらの電池に電槽化成を施し、５ｈＲ放電試験を繰り返し行った。５ｈＲ放電試験において５．６Ａで終止電圧１０．５Ｖまで放電して放電容量を調べ、２．８Ａで放電電気量の１３５％まで充電する充放電サイクルを繰り返した。試験温度は２５℃とした。
【００１６】
図１にこれらの電池の５ｈＲ放電容量の推移を示す。熟成温度が５０℃であればペースト混練時の希硫酸投入方法にかかわらず、いずれの電池（〓１〜４）も充分な初期容量を示すものの比較的早期に容量が低下した。一方、熟成温度が７０℃の場合、希硫酸滴下品（〓５）は優れた寿命性能を示したものの、放電容量が非常に小さかった。希硫酸全量投入品（〓６〜８）は、１サイクル目の放電容量が５０℃熟成品にはわずかにおよばなかったものの、３サイクル目の放電容量が５０℃熟成品よりも大きく、しかも優れた寿命性能を示した。
【００１７】
このように充放電サイクル中の容量推移が大きく異なった原因を調査するために３サイクル後の正極活物質の細孔分布を水銀圧入法によって調べた結果を図２に示す。熟成温度が５０℃であればペースト混練時の希硫酸投入方法にかかわらず、いずれの正極活物質（〓１〜４）も直径０．２〜５μｍの細孔が多く、全細孔量は約０．１４ｃｃ／ｇであった。一方、熟成温度が７０℃の場合（〓５〜８）、いずれの正極活物質も全細孔量は約０．１４ｃｃ／ｇであり大差なかったものの、細孔分布は直径０．２〜５μｍと５〜５０μｍの２種類に大別され、これらの割合がペースト処方によって異なることがわかった。すなわち、〓５、６、７および８の正極活物質中の直径５〜５０μｍの細孔量はそれぞれ全細孔量の約４５、３５、２５および１５％を占めていた。
【００１８】
上記の正極活物質の細孔分布と電池の寿命性能との関係から次のことがわかった。正極活物質が有する細孔直径の大部分が５μｍ以下の場合（〓１〜４）、充分な初期容量を示すものの比較的早期に容量が低下した。正極活物質が直径５〜５０μｍの細孔を全細孔量の４５％程度以上有する場合（〓５）、優れた寿命性能を示すものの放電容量は非常に小さかった。正極活物質が直径５〜５０μｍの細孔を全細孔量の１５〜３５％有する本発明による電池の場合（〓６〜８）、初期容量が大きくしかも優れた寿命性能を示した。
【００１９】
通常正極板の放電容量は活物質内部への電解液（硫酸イオン）の拡散速度によって律速されることから、例えば活物質の多孔度が大きい（細孔量が大きい）ほどその拡散速度が大きく放電容量が増大することは知られている。ただし、活物質の多孔度が大きいほど寿命性能が低下することも知られている。また、多孔度が同じ場合でも細孔径が大きいほど、硫酸イオンの拡散速度は大きいはずである。したがって、活物質の細孔径を大きくすることによって活物質内部まで硫酸イオンの拡散を助けることは初期性能の向上に非常に有効である。ところが、活物質の細孔径全体を大きくしてしまうと活物質の表面積が低下し、活物質の反応性が大きく低下してしまい、放電容量はむしろ低下してしまう。
【００２０】
本発明では全細孔量の１５〜３５％の細孔のみを直径５〜５０μｍまで大きくしたことによって、活物質表面積の低下を招くことなく電解液の拡散速度を増大させることができたために、３サイクル目以降の放電容量を従来よりも増大させることができたものと思われる。ただし、１サイクル目の放電容量にその効果がみられなかったのは、後述する未化活物質中の四塩基性硫酸鉛の生成によって化成性が低下し、電槽化成直後の二酸化鉛量がやや少なかったためと思われる。
【００２１】
正極板処方の違いによって正極活物質の細孔分布の違いがみられた原因を調べるために、これらの未化成正極板（熟成後正極板）の断面を観察・調査した。
【００２２】
ペースト処方の違いによって未化成活物質中の硫酸の分布が異なるため、５０℃熟成品では〓１、２、３および４の順で次第に凝集部（硫酸の多い部分）が大きくなった。なお、これらの組成は3PbO・PbSO₄・H₂O(三塩基性硫酸鉛)、t-PbOおよびPbO・PbSO₄(一塩基性硫酸鉛)からなり、凝集部は3PbO・PbSO₄・H₂OおよびPbO・PbSO₄の含有率が高かった。
【００２３】
一方、７０℃熟成品では〓５、６、７および８の順で次第に凝集部（硫酸の多い部分）が大きくなった。また、凝集部には4PbO・PbSO₄(四塩基性硫酸鉛)が生成しており、その他の部分は3PbO・PbSO₄・H₂Oおよびt-PbOからなっていた。なお、四塩基性硫酸鉛の生成状況が部位によって異なったのはペースト中の硫酸量の違いに起因していることから、硫酸量が比較的多い部位は四塩基性硫酸鉛の生成温度が低いことを示唆している。
【００２４】
次に、これらの未化成活物質の細孔分布を調べた結果を図３に示す。５０℃熟成品（〓１〜４）ではいずれも直径０．２〜１μｍの細孔を有していた。このことは3PbO・PbSO₄・H₂O、t-PbOおよびPbO・PbSO₄の粒子サイズが比較的近似していることを示唆している。一方、７０℃熟成品では直径０．２〜８μｍの細孔と８〜３０μｍの細孔の割合がペースト処方によって異なった。すなわち、〓５、６、７および８の正極活物質中における直径５〜５０μｍの細孔量はそれぞれ全細孔量の約４５、３５、２５および１５％を占めていた。このように細孔直径が２つに大別された理由は3PbO・PbSO₄・H₂Oやt-PbOの粒子サイズが０．２〜５μｍと小さく、4PbO・PbSO₄の粒子サイズが５〜２００μｍと大きいためで、これらの分布状況の違いによって細孔分布が異なったものと思われる。
【００２５】
また、未化成活物質と化成後活物質の細孔分布を比較すると、細孔直径や細孔量に若干の変化はみられるものの、未化成時の細孔分布が化成後にも反映されているといえる。
【００２６】
以上のように、正極ペースト中の硫酸凝集部の大きさをコントロールすることによって、熟成後の4PbO・PbSO₄の分布を変え、このことによって正極活物質の全細孔体積の１５〜３５％を細孔直径５〜５０μｍとしたことは電池性能の向上に非常に有効であった。なお、正極活物質中の細孔直径５〜５０μｍを除く細孔については、そのほとんどが直径５μｍ以下の微細な細孔であることは言うまでもない。
【発明の効果】
以上、実施例で述べたように、本発明による鉛蓄電池を用いれば、鉛蓄電池の寿命性能を向上させることができるだけでなく、高容量化もはかることができ、その工業的価値は甚だ大なるものである。
【図面の簡単な説明】
【図１】５ｈＲ放電容量の推移を示す図である。
【図２】正極活物質の細孔分布を示す図である。
【図３】未化成活物質の細孔分布を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a positive electrode plate for a lead storage battery.
[0002]
[Prior art]
Currently, lead-acid batteries are used in various fields including automobiles and industrial use. Among them, the battery for automobiles has the highest demand, and there is a demand for weight reduction, cost reduction, maintenance-free, long life, and quality stabilization.
[0003]
Currently, the lattice alloys used in lead-acid batteries can be broadly classified into lead-antimony and lead-calcium-tin (hereinafter referred to as lead-calcium), and the characteristics of lead-acid batteries differ significantly depending on these lattice alloys. It is known. That is, a lead-acid battery using a positive electrode lattice of a lead-antimony alloy exhibits excellent characteristics in a deep charge / discharge cycle, but has a drawback of large self-discharge. On the other hand, lead-acid batteries using a lead-calcium alloy positive electrode grid have low self-discharge and excellent maintenance-free characteristics such as no need for water replenishment due to low liquid reduction during use, but repeated charge / discharge cycles However, there is a drawback that the discharge capacity may decrease relatively early.
[0004]
In general, it is known that the capacity reduction of a lead-acid battery occurs because the positive electrode active material particles become coarse during charge / discharge cycles and the bondability between the particles decreases. This phenomenon is called softening of the active material, and is known to occur particularly from the active material layer on the surface of the electrode plate and gradually expand to the internal active material. The softening of the active material is more likely to occur as the amount of antimony in the positive electrode lattice alloy decreases, and it is considered that antimony has some influence on the deterioration of the positive electrode active material.
[0005]
Conventionally, lead acid batteries are manufactured as follows. That is, a lead alloy grid is filled with a paste of 60 to 95% of the degree of oxidation (weight% of lead monoxide) paste-diluted with dilute sulfuric acid, and then subjected to aging and drying to produce an unformed electrode plate. To do. A battery assembled using these is formed into a charged battery by forming a battery case with a quantity of electricity of 200 to 400% of the theoretical quantity of electricity of the positive electrode active material.
[0006]
[Problems to be solved by the invention]
In particular, when a lead-calcium alloy is used as a positive electrode lattice, the above-described ripening process is improved, for example, a method of generating tetrabasic lead sulfate in an unformed active material by aging at high temperature and high humidity, etc. Has been proposed.
[0007]
Since tetrabasic lead sulfate crystals are larger than tribasic lead sulfate, which is a conventional aging product, lead dioxide that has a strong skeleton of tetrabasic lead sulfate is formed by this method. Since it is sometimes formed, there is an advantage that excellent life performance can be obtained. However, a coarse crystal of tetrabasic lead sulfate is inferior in chemical conversion, that is, since the inside of the crystal is not converted into lead dioxide, there is a drawback that sufficient initial performance cannot be obtained.
[0008]
[Means for Solving the Problems]
The present invention solves the problems as described above, and is characterized in that 15 to 35% of the total pore volume of the positive electrode active material has a pore diameter of 5 to 50 μm. As a result, the capacity and life of the lead-acid battery positive plate are increased.
[0009]
The positive electrode plate for a lead storage battery according to the present invention is configured such that 15 to 35% of the total pore volume of the positive electrode active material has a pore diameter of 5 to 50 μm by adjusting the kneading procedure of lead powder, water and dilute sulfuric acid. was this and features, more preferably to, and forming a step of forming a slurry by kneading a lead powder and water, the kneaded to active material paste after standing a predetermined dilute sulfuric acid was added to the slurry time, the A step of obtaining an unformed electrode plate having an agglomerated portion of tetrabasic lead sulfate in the active material by filling an active material paste into a grid made of a lead alloy, and a step of forming the unformed electrode plate; It is obtained by the manufacturing method provided with.
[0010]
【Example】
Hereinafter, the present invention will be described based on examples.
[0011]
A positive electrode paste was prepared by kneading 100 kg of ball mill type lead powder, 12 liters of water and 8 liters of dilute sulfuric acid having a specific gravity of 1.4. The kneading procedure was performed under the following conditions.
[0012]
First, a predetermined amount of lead powder and water were put into a kneader and kneaded for 5 minutes to obtain a uniform slurry. A predetermined amount of dilute sulfuric acid was added to the slurry and kneaded to prepare four types of pastes with different dilute sulfuric acid charging methods. That is, the paste in 〓1 was added dropwise with the entire amount of dilute sulfuric acid while kneading the slurry (drop time 30 minutes), and the paste in 〓2 was kneaded for 10 minutes after the entire amount of dilute sulfuric acid was added to the slurry. Into the slurry, the entire amount of dilute sulfuric acid was added and allowed to stand for 10 minutes, and then kneaded for 10 minutes, and in the paste 4, the entire amount of diluted sulfuric acid was added to the slurry and allowed to stand for 30 minutes and then kneaded for 10 minutes.
[0013]
The reason why the paste method was changed was to change the distribution of sulfuric acid in the paste. Among these pastes, sulfuric acid was most uniformly distributed in the paste of 〓1, followed by 〓2, 〓 3 and 〓4 are gradually and non-uniformly distributed, that is, the agglomerate of sulfuric acid is enlarged.
[0014]
These four types of pastes were filled in a casting grid using a normal Pb—Ca—Sn alloy by a conventional method, and aged for 24 hours in an aging chamber at two temperatures of 50 ° C. and 70 ° C. The relative humidity in the aging room was 100% at any temperature. The aged electrode plate was dried in a 50 ° C. drying room (relative humidity 25%) for 3 days to obtain 8 types of unformed positive electrode plates shown in Table 1.
[0015]
[Table 1]

The electrode plate used here had a height of 110 mm, a width of 108 mm, and a thickness of 2.0 mm, and the active material density after chemical conversion was about 3.8 g / cm ³ . These unformed positive electrode plates 4 cells / cell and normal unformed anode plates 5 cells / cell using a Pb—Ca—Sn alloy lattice are laminated through a ribbed polyethylene separator, and an automobile defined in JIS D5301. A lead storage battery 36B20 (5 hour rate capacity: 28 Ah) was assembled. Then, these batteries were subjected to battery case formation, and the 5 hR discharge test was repeated. In the 5 hR discharge test, the discharge capacity was examined by discharging to 5.6 A at a final voltage of 10.5 V, and the charge / discharge cycle was charged at 2.8 A to 135% of the discharged electricity. The test temperature was 25 ° C.
[0016]
FIG. 1 shows the transition of the 5hR discharge capacity of these batteries. When the aging temperature was 50 ° C., regardless of the dilute sulfuric acid charging method at the time of paste kneading, all the batteries (〓1 to 4) exhibited a sufficient initial capacity, but the capacity decreased relatively early. On the other hand, when the aging temperature was 70 ° C., the dilute sulfuric acid dropping product (〓5) showed excellent life performance, but the discharge capacity was very small. Dilute sulfuric acid input product (〓6-8) had a discharge capacity at the first cycle slightly lower than that at 50 ° C aging product, but the discharge capacity at the third cycle was larger than that at 50 ° C aging product, and it was excellent Long life performance was demonstrated.
[0017]
FIG. 2 shows the result of examining the pore distribution of the positive electrode active material after three cycles by the mercury intrusion method in order to investigate the cause of the large difference in capacity transition during the charge / discharge cycle. When the aging temperature is 50 ° C., regardless of the dilute sulfuric acid charging method at the time of paste kneading, all the positive electrode active materials (〓 1 to 4) have many pores having a diameter of 0.2 to 5 μm, and the total pore amount is about It was 0.14 cc / g. On the other hand, when the aging temperature was 70 ° C. (〓5 to 8), the total pore amount of any positive electrode active material was about 0.14 cc / g, and the pore distribution was 0.2 to 5 μm in diameter. And 5 to 50 μm, and these ratios were found to differ depending on the paste formulation. That is, the amount of pores having a diameter of 5 to 50 μm in the positive electrode active materials of

ridges

5, 6, 7 and 8 respectively accounted for about 45, 35, 25 and 15% of the total pore amount.
[0018]
The following was found from the relationship between the pore distribution of the positive electrode active material and the life performance of the battery. When most of the pore diameters of the positive electrode active material were 5 μm or less (〓 1 to 4), the capacity decreased relatively early although it showed a sufficient initial capacity. When the positive electrode active material had pores having a diameter of 5 to 50 μm in an amount of about 45% or more of the total pore amount (もの 5), the discharge capacity was very small although excellent life performance was exhibited. In the case of the battery according to the present invention in which the positive electrode active material had pores having a diameter of 5 to 50 μm and 15 to 35% of the total pore amount (〓6 to 8), the initial capacity was large and excellent life performance was exhibited.
[0019]
Normally, the discharge capacity of the positive electrode plate is controlled by the diffusion rate of the electrolyte (sulfate ion) into the active material. For example, the greater the porosity of the active material (the larger the amount of pores), the greater the diffusion rate. It is known that capacity increases. However, it is also known that the life performance decreases as the porosity of the active material increases. Even if the porosity is the same, the larger the pore diameter, the greater the diffusion rate of sulfate ions. Therefore, assisting the diffusion of sulfate ions into the active material by increasing the pore size of the active material is very effective in improving the initial performance. However, if the entire pore diameter of the active material is increased, the surface area of the active material is decreased, the reactivity of the active material is greatly decreased, and the discharge capacity is rather decreased.
[0020]
In the present invention, by increasing only the pores of 15 to 35% of the total pore amount to a diameter of 5 to 50 μm, it was possible to increase the diffusion rate of the electrolytic solution without causing a reduction in the active material surface area. It seems that the discharge capacity after the third cycle could be increased more than before. However, the effect was not seen in the discharge capacity at the first cycle because the formation of tetrabasic lead sulfate in the unactivated active material described later deteriorates the conversion, and the amount of lead dioxide immediately after the battery formation is reduced. It seems that it was a little less.
[0021]
In order to investigate the cause of the difference in the pore distribution of the positive electrode active material due to the difference in the positive electrode plate formulation, the cross sections of these unformed positive electrode plates (post-aged positive electrode plates) were observed and investigated.
[0022]
Since the distribution of sulfuric acid in the non-chemically active material differs depending on the paste formulation, the agglomerated portion (the portion rich in sulfuric acid) gradually increased in the order of 〓 1, 2, 3 and 4 in the 50 ° C. aged product. Incidentally, these compositions _{_{3PbO · PbSO 4 · H 2 O}} ( tribasic lead sulfate), t-PbO and PbO · PbSO ₄ consists (monobasic lead sulfate), aggregation unit 3PbO · PbSO ₄ · H ₂ The content of O and PbO · PbSO ₄ was high.
[0023]
On the other hand, in the 70 ° C. aged product, the agglomerated portion (portion rich in sulfuric acid) gradually increased in the order of

cocoons

5, 6, 7 and 8. In addition, 4PbO · PbSO ₄ (tetrabasic lead sulfate) was formed in the agglomerated part, and the other part was composed of 3PbO · PbSO ₄ · H ₂ O and t-PbO. In addition, since the production situation of tetrabasic lead sulfate was different depending on the part, it was due to the difference in the amount of sulfuric acid in the paste. Suggests that.
[0024]
Next, the results of examining the pore distribution of these unformed active materials are shown in FIG. The 50 ° C. aged products (〓 1 to 4) all had pores having a diameter of 0.2 to 1 μm. This suggests that the particle sizes of 3PbO · PbSO ₄ · H ₂ O, t-PbO and PbO · PbSO ₄ are relatively close. On the other hand, in the 70 ° C. aged product, the ratio of the pores having a diameter of 0.2 to 8 μm and the pores of 8 to 30 μm differed depending on the paste formulation. That is, the amount of pores having a diameter of 5 to 50 μm in the positive electrode active materials of the

ridges

5, 6, 7 and 8 accounted for about 45, 35, 25 and 15% of the total pore amount, respectively. The reason why the pore diameter is roughly divided into two is that the particle size of 3PbO · PbSO ₄ · H ₂ O and t-PbO is as small as 0.2 to 5 μm, and the particle size of 4PbO · PbSO ₄ is 5 to 5 μm. Since it is as large as 200 μm, it seems that the pore distribution differs depending on the difference in the distribution conditions.
[0025]
In addition, when comparing the pore distributions of the unformed active material and the post-formed active material, the pore diameter and the amount of pore are slightly changed, but the pore distribution at the time of unformed is also reflected after the formation. It can be said.
[0026]
As described above, by controlling the size of the sulfuric acid agglomeration part in the positive electrode paste, the distribution of 4PbO · PbSO ₄ after aging is changed, and as a result, 15 to 35% of the total pore volume of the positive electrode active material is reduced. The pore diameter of 5 to 50 μm was very effective for improving battery performance. Needless to say, most of the pores other than the pore diameter of 5 to 50 μm in the positive electrode active material are fine pores having a diameter of 5 μm or less.
【The invention's effect】
As described above, when the lead storage battery according to the present invention is used as described in the embodiments, not only can the life performance of the lead storage battery be improved, but also the capacity can be increased, and its industrial value is extremely large. Is.
[Brief description of the drawings]
FIG. 1 is a graph showing the transition of 5hR discharge capacity.
FIG. 2 is a view showing a pore distribution of a positive electrode active material.
FIG. 3 is a view showing a pore distribution of an unformed active material.

Claims

A step of kneading lead powder and water to form a slurry, a step of adding dilute sulfuric acid to the slurry and kneading after standing for a predetermined time to form an active material paste, and filling the active material paste into a lead alloy lattice Then, aging is performed to obtain an unformed electrode plate having an agglomerated portion of tetrabasic lead sulfate in the active material, and 15 to 35 of the total pore volume of the positive electrode active material formed by forming the unformed electrode plate. % positive electrode plate manufacturing method for a lead storage battery, characterized in that it comprises a step of obtaining a positive electrode plate for a lead storage battery is a pore diameter 5 to 50 [mu] m, a.