JP2004047301A

JP2004047301A - Control valve type lead-acid battery

Info

Publication number: JP2004047301A
Application number: JP2002203828A
Authority: JP
Inventors: Toshibumi Yoshimine; 吉嶺　俊文; Takehiro Sasaki; 佐々木　健浩; Tomoki Fujimori; 藤森　智貴; Takashi Nakajima; 中嶋　孝
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2002-07-12
Filing date: 2002-07-12
Publication date: 2004-02-12
Anticipated expiration: 2022-07-12
Also published as: JP4423840B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost control valve type lead-acid battery having excellent lifetime characteristics while minimizing the content of Sn in a positive electrode collector. <P>SOLUTION: The control valve type lead-acid battery comprises an electrode plate group composed of a positive electrode plate and a negative electrode plate, a battery jar for housing the electrode plate group, and a lid for covering the opening of the battery jar. The positive electrode plate includes a positive electrode collector made of a Pb-Sn alloy and a positive electrode active material. The negative electrode plate includes a negative electrode collector made of a Pb alloy and a porous negative electrode active material. At least one of the battery jar and the lid is provided with a safety valve that opens and closes depending on the internal pressure of the battery. The positive electrode collector contains 0.4 to 1.8 mass % of Sn. The vacancy volume (pore volume) per unit mass of the negative electrode active material is set to 0.07 to 0.11 cm<SP>3</SP>/g. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は充電時に正極で発生した酸素ガスを負極で吸収する構成を有した制御弁式鉛蓄電池に関するものである。
【０００２】
【従来の技術】
非常用電源に用いる蓄電池として制御弁式鉛蓄電池が広く用いられている。その中でも通信用やコンピュータ用の非常用電源では長期間にわたって高い信頼性が求められる。これらの非常用電源に用いる制御弁式鉛蓄電池は停電時に負荷を作動できるよう、常に充電（トリクル充電）を行う。制御弁式鉛蓄電池ではこのトリクル充電として蓄電池を構成する単位セルあたり２．３Ｖ程度の電圧で定電圧充電を行うことが行われている。
【０００３】
トリクル充電を常時行う場合、蓄電池にはトリクル電流が流れる。このトリクル電流によって正極集電体は酸化を受けて腐食する。このような腐食によって正極集電体の集電効率が低下し、それにより電池の容量低下が進行し寿命にいたる。
【０００４】
鉛蓄電池の中でも特に充電中に正極で発生した酸素ガスを負極で吸収する制御弁式鉛蓄電池の場合、酸素ガスによって負極が酸化して酸化鉛を生成し、これが電解液中の硫酸と反応して硫酸鉛を生成することによって、負極の電位は貴に移行し、充電電圧は低下する。電池を定電圧でトリクル充電する場合にはこのような充電電圧の低下に対応して充電電流（トリクル電流）が増加する。このようなトリクル電流の増加は前記したような正極集電体の腐食を促進し、結果として電池の寿命を低下させる。
【０００５】
このような正極集電体の腐食による寿命低下を抑制するために、正極集電体の耐食性を向上させるための検討が種々なされてきた。その中でも正極集電体の耐食性を向上させるために正極集電体を構成するＰｂ−Ｓｎ合金もしくはＰｂ−Ｃａ−Ｓｎ合金中のＳｎ含有量として１．８質量％を越えて２．５質量％までの範囲に設定することが知られている。
【０００６】
正極集電体中のＳｎ含有量を増加させることによって集電体の耐食性は向上し、電池寿命が向上するものの、ＳｎがＰｂに比較して高価であるために電池価格がより高価となるという問題があった。
【０００７】
【発明が解決しようとする課題】
本発明は前記したような正極集電体中のＳｎの添加を最小限に抑制しながら寿命特性に優れた制御弁式鉛蓄電池を安価に提供することを目的とする。
【０００８】
【課題を解決するための手段】
前記した課題を解決するために、本発明の請求項１に係る発明は、Ｐｂ−Ｓｎ合金からなる正極集電体と正極活物質を有した正極板とＰｂ合金からなる負極集電体と多孔質の負極活物質を有した負極板を備えた極板群と、この極板群を収納する電槽と、この電槽の開口部を覆う蓋と備え、これら電槽もしくは蓋の少なくともいずれか一方に電池内圧によって開閉する安全弁を備えた制御弁式鉛蓄電池において、正極集電体はＳｎを０．４質量％〜１．８質量％含むとともに、負極活物質の単位質量当たりの空孔体積を０．０７ｃｍ^３／ｇ〜０．１１ｃｍ^３／ｇとしたことを特徴とした制御弁式鉛蓄電池を示すものである。
【０００９】
また、本発明の請求項２に係る発明は請求項１の構成を有する制御弁式鉛蓄電池において、安全弁の開弁圧を４０００Ｐａ〜１１０００Ｐａとしたことを特徴とするものである。
【００１０】
【発明の実施の形態】
本発明の実施の形態による制御弁式鉛蓄電池の構成を説明する。
【００１１】
本発明の電池に用いる正極集電体としては０．４質量％〜１．８質量％のＳｎを含むＰｂ−Ｓｎ合金を用いる。巻回式の極板群を構成する場合には、集電体が変形する必要があるのでＰｂ−Ｓｎ合金中にＣａを添加することは好ましくない。平板状の極板を積層して極板群を構成する場合には極板自体の変形を抑制する必要性からＰｂ−Ｓｎ合金中に０．０３質量％〜０．１０質量％程度のＣａを添加する。
【００１２】
前記した組成のＰｂ−Ｓｎ合金を用いて従来から知られている鋳造法やエキスパンド法により正極集電体を得る。この正極集電体に定法によって得た活物質ペーストを充填し、熟成乾燥することによって未化成の正極板を得る。
【００１３】
負極集電体は正極板と同じＰｂ−Ｓｎ合金に加えてＰｂ−Ｃａ合金等を用いることができる。負極集電体上には負極活物質ペーストを充填し、熟成乾燥して未化成の負極板を得る。未化成の正極板と負極板をガラス繊維セパレータ等のリテーナと組み合わせて極板群を構成し、この極板群を電槽に収納した後、電槽開口部を蓋で覆う。次に電解液を注液後、化成充電を行うことによって未化成の活物質を正極と負極でそれぞれ多孔質の二酸化鉛と鉛とする。
【００１４】
本発明の制御弁式鉛蓄電池は多孔質鉛で構成される負極活物質の単位質量当たりの空孔体積（細孔体積）を０．０７ｃｍ^３／ｇ〜０．１１ｃｍ^３／ｇとする。負極活物質の細孔体積をこのような値とすることによって負極でのガス吸収反応を抑制し、この反応に基づくトリクル電流の増加を抑制する。トリクル電流の増加を抑制することによって、耐食性向上の目的で正極集電体に添加していたＳｎ量を従来の２．２質量％程度から０．４質量％〜１．８質量％の範囲で低減することができる。負極活物質の細孔体積は活物質原料に用いる鉛粉（一般的には鉛と鉛酸化物との混合物）への水もしくは希硫酸の添加量によって制御することができる。
【００１５】
また、本発明の制御弁式鉛蓄電池は従来のものと同様、電槽もしくは蓋の少なくともいずれか一方に電池内圧と大気圧との差に応じて開閉動作する安全弁を備えている。但し、本発明においては開弁圧（弁が開動作するときの電池内圧から大気圧を差し引いた値）を４０００Ｐａ〜１１０００Ｐａの範囲に設定することが好ましい。開弁圧を１１０００Ｐａを越えて設定した場合、トリクル充電時の電池内の酸素分圧の増加に伴い、トリクル電流値が増加し、正極集電体の腐食が促進されるためである。
【００１６】
このような本発明の構成によって、従来優れたトリクル寿命特性を得るために正極集電体に多量添加していたＳｎ量を低減することによっても、優れたトリクル寿命特性を有した制御弁式鉛蓄電池を安価に提供することが可能となる。
【００１７】
【実施例】
〈実施例１〉
正極集電体の合金組成および負極活物質の細孔体積を種々変化させて２Ｖ１００Ａｈの制御弁式鉛蓄電池を作成し、トリクル寿命試験を行った。
【００１８】
ここで正極集電体の合金組成はＰｂ−０．０９質量％Ｃａ−０．２５〜２．５質量％ＳｎでＳｎ量を変化させ、負極集電体の合金組成はＰｂ−０．０９質量％Ｃａで一定とした。負極活物質はボールミル式鉛粉（３０質量％Ｐｂ＋７０質量％ＰｂＯ）に水と希硫酸を添加し、混練して得た活物質ペーストを集電体に塗着して得た。本実施例においては混練に用いる水量と希硫酸量を変化させることによって、化成充電後の負極活物質の細孔体積を０．０５ｃｍ^３／ｇ〜０．１５ｃｍ^３／ｇに変化させた。また、各電池には開弁圧が１００００Ｐａ、閉弁圧が３０００Ｐａの安全弁を設けた。
【００１９】
これらの各電池について４０℃中におけるトリクル寿命試験を行った。トリクル寿命試験方法としては、各電池を４０℃雰囲気下で２．２７５Ｖ定電圧で３ヶ月連続充電を行った後、電池を２５℃中で２４時間放置し、２５Ａ定電流放電を放電終止電圧１．７５Ｖまで行ったときの放電容量を測定した。この定電圧充電と放電のサイクルを繰返して行い、放電容量が初期の８０％まで低下した時点で寿命終了とした。これら各電池のトリクル寿命特性を図１に示す。
【００２０】
図１に示した結果から、負極細孔体積を０．０７〜０．１１ｃｍ^３／ｇとすることにより、正極集電体中のＳｎ濃度を２．０、２．５質量％から０．４質量％〜１．８質量％に低減しても良好な寿命特性が得られることがわかる。負極細孔体積を０．０７ｃｍ^３／ｇより減少させて０．０５ｃｍ^３／ｇとした場合、正極集電体中のＳｎ濃度に係わらず、寿命特性は低下する。これは細孔体積をある程度以下に減少させるとトリクル寿命試験中に細孔体積の減少が促進され、容量低下が進行しやすくなるためと推測される。
【００２１】
〈実施例２〉
実施例１において、正極集電体中のＳｎ量を１．２質量％、負極活物質の細孔体積を０．０９ｃｍ^３／ｇとした電池について安全弁の開弁圧を２０００Ｐａから１５０００Ｐａに変化させた電池を作成し、実施例１と同条件でトリクル寿命試験を行った。その結果を図２に示す。
【００２２】
図２に示した結果より、開弁圧が１１０００Ｐａを超えて高くなるとトリクル寿命は低下する傾向があることがわかる。開弁圧の上昇とともにトリクル寿命試験時のトリクル充電電流が増加する傾向があり、正極集電体の腐食が促進されることによって寿命が低下した。これは開弁圧の上昇によって電池内の酸素分圧が上昇し、負極における酸素ガス吸収反応が促進されたことによると推測される。
【００２３】
また、開弁圧が４０００Ｐａよりも低く設定してもトリクル寿命は低下する。このような電池はトリクル充電時の液減りが他の電池に比較して大きく、電解液中の水分量が低下することによる内部抵抗の増大によって容量低下し、寿命にいたる。したがって開弁圧は少なくとも４０００Ｐａ以上に設定することが好ましいが、特に１１０００Ｐａ以下に設定すればトリクル充電電流の増加をより抑制することができ、より優れたトリクル寿命特性を有した電池を得ることができる。
【００２４】
【発明の効果】
以上、説明してきたように、本発明の構成によれば、従来、優れたトリクル寿命特性を得るために正極集電体に多量添加していた高価なＳｎの添加量を低減しながらも優れたトリクル寿命特性を有した制御弁式鉛蓄電池を安価に提供することが可能となり、工業上、極めて有用である。
【図面の簡単な説明】
【図１】実施例１における本発明例および比較例の電池のトリクル寿命特性を示す図
【図２】実施例２における本発明例および比較例の電池のトリクル寿命特性を示す図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control valve type lead storage battery having a configuration in which oxygen gas generated at a positive electrode during charging is absorbed by the negative electrode.
[0002]
[Prior art]
As a storage battery used for an emergency power source, a control valve type lead storage battery is widely used. Among them, an emergency power source for communication and computers is required to have high reliability over a long period of time. The control valve type lead-acid batteries used for these emergency power supplies always charge (trickle charge) so that the load can be activated during a power failure. In the control valve type lead-acid battery, constant voltage charging is performed at a voltage of about 2.3 V per unit cell constituting the battery as trickle charging.
[0003]
When trickle charging is always performed, trickle current flows through the storage battery. By this trickle current, the positive electrode current collector is oxidized and corroded. Such corrosion lowers the current collection efficiency of the positive electrode current collector, thereby leading to a decrease in the capacity of the battery and reaching its life.
[0004]
Among lead-acid batteries, especially in the case of a control valve type lead-acid battery that absorbs oxygen gas generated at the positive electrode during charging at the negative electrode, the negative electrode is oxidized by oxygen gas to produce lead oxide, which reacts with sulfuric acid in the electrolyte. By generating lead sulfate, the potential of the negative electrode shifts to noble and the charging voltage decreases. When the battery is trickle charged at a constant voltage, the charging current (trickle current) increases corresponding to such a decrease in the charging voltage. Such an increase in trickle current promotes the corrosion of the positive electrode current collector as described above, resulting in a reduction in battery life.
[0005]
In order to suppress such a life reduction due to corrosion of the positive electrode current collector, various studies have been made to improve the corrosion resistance of the positive electrode current collector. Among these, in order to improve the corrosion resistance of the positive electrode current collector, the Sn content in the Pb—Sn alloy or Pb—Ca—Sn alloy constituting the positive electrode current collector exceeds 1.8% by mass and is 2.5% by mass. It is known to set the range up to.
[0006]
Increasing the Sn content in the positive electrode current collector improves the corrosion resistance of the current collector and improves the battery life, but the battery price is more expensive because Sn is more expensive than Pb. There was a problem.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a control valve type lead storage battery having excellent life characteristics while suppressing the addition of Sn in the positive electrode current collector as described above at a low cost.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, the invention according to claim 1 of the present invention includes a positive electrode current collector made of a Pb—Sn alloy, a positive electrode plate having a positive electrode active material, a negative electrode current collector made of a Pb alloy, and a porous material. A negative electrode plate having a negative electrode active material, a battery case containing the electrode plate group, and a lid covering the opening of the battery case, and at least one of these battery case and lid In a control valve type lead-acid battery having a safety valve that opens and closes depending on the internal pressure of the battery, the positive electrode current collector contains 0.4 mass% to 1.8 mass% of Sn, and the pore volume per unit mass of the negative electrode active material the shows a valve-regulated lead-acid battery which is characterized in that a 0.07cm ^³ /g~0.11cm ³ / g.
[0009]
Further, the invention according to claim 2 of the present invention is characterized in that, in the control valve type lead-acid battery having the configuration of claim 1, the valve opening pressure of the safety valve is 4000 Pa to 11000 Pa.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
A configuration of a control valve type lead storage battery according to an embodiment of the present invention will be described.
[0011]
As the positive electrode current collector used in the battery of the present invention, a Pb—Sn alloy containing 0.4 mass% to 1.8 mass% Sn is used. In the case of forming a wound electrode group, it is not preferable to add Ca to the Pb—Sn alloy because the current collector needs to be deformed. When a plate group is formed by laminating flat plate plates, about 0.03% to 0.10% by mass of Ca is contained in the Pb—Sn alloy because of the necessity of suppressing deformation of the plate itself. Added.
[0012]
A positive electrode current collector is obtained by a conventionally known casting method or expanding method using the Pb—Sn alloy having the composition described above. The positive electrode current collector is filled with an active material paste obtained by a conventional method and aged and dried to obtain an unformed positive electrode plate.
[0013]
For the negative electrode current collector, a Pb—Ca alloy or the like can be used in addition to the same Pb—Sn alloy as the positive electrode plate. A negative electrode active material paste is filled on the negative electrode current collector and aged and dried to obtain an unformed negative electrode plate. An unformed positive electrode plate and negative electrode plate are combined with a retainer such as a glass fiber separator to form an electrode plate group. After the electrode plate group is accommodated in the battery case, the battery case opening is covered with a lid. Next, after injecting the electrolytic solution, chemical conversion charging is performed to convert the unformed active material into porous lead dioxide and lead respectively at the positive electrode and the negative electrode.
[0014]
Valve-regulated lead-acid battery of the present invention is the pore volume per unit mass of the negative electrode active material composed of a porous lead (the pore volume) and 0.07cm ^³ /g~0.11cm ³ / g. By setting the pore volume of the negative electrode active material to such a value, the gas absorption reaction at the negative electrode is suppressed, and an increase in trickle current based on this reaction is suppressed. By suppressing the increase of the trickle current, the Sn amount added to the positive electrode current collector for the purpose of improving the corrosion resistance is in the range of about 2.2% by mass to 0.4% by mass to 1.8% by mass. Can be reduced. The pore volume of the negative electrode active material can be controlled by the amount of water or dilute sulfuric acid added to the lead powder (generally a mixture of lead and lead oxide) used as the active material raw material.
[0015]
Moreover, the control valve type lead acid battery of this invention is equipped with the safety valve which opens and closes according to the difference of a battery internal pressure and atmospheric pressure in at least one of a battery case or a lid | cover like a conventional thing. However, in the present invention, the valve opening pressure (a value obtained by subtracting the atmospheric pressure from the battery internal pressure when the valve is opened) is preferably set in the range of 4000 Pa to 11000 Pa. This is because when the valve opening pressure is set to exceed 11000 Pa, the trickle current value increases as the partial pressure of oxygen in the battery during trickle charging increases, and corrosion of the positive electrode current collector is promoted.
[0016]
With such a configuration of the present invention, a control valve type lead having excellent trickle life characteristics can be obtained by reducing the amount of Sn that has been added in a large amount to the positive electrode current collector in order to obtain excellent trickle life characteristics. A storage battery can be provided at low cost.
[0017]
【Example】
<Example 1>
A control valve type lead storage battery of 2V100Ah was prepared by variously changing the alloy composition of the positive electrode current collector and the pore volume of the negative electrode active material, and a trickle life test was performed.
[0018]
Here, the alloy composition of the positive electrode current collector is Pb-0.09 mass% Ca-0.25 to 2.5 mass% Sn, and the Sn amount is changed, and the negative electrode current collector alloy composition is Pb-0.09 mass. % Ca was constant. The negative electrode active material was obtained by adding water and dilute sulfuric acid to ball mill type lead powder (30% by mass Pb + 70% by mass PbO) and kneading the active material paste obtained by kneading to the current collector. By varying the amount of water and dilute sulfuric acid amount used for kneading in the present embodiment, changing the pore volume of the negative electrode active material after the chemical conversion charge into 0.05cm ^³ /g~0.15cm ³ / g. Each battery was provided with a safety valve having a valve opening pressure of 10,000 Pa and a valve closing pressure of 3000 Pa.
[0019]
Each of these batteries was subjected to a trickle life test at 40 ° C. As a trickle life test method, each battery was continuously charged for 3 months at 2.275 V constant voltage in an atmosphere of 40 ° C., then the battery was left to stand at 25 ° C. for 24 hours, and a 25 A constant current discharge was performed at a discharge end voltage 1 The discharge capacity when measured up to .75V was measured. This constant voltage charging and discharging cycle was repeated, and when the discharge capacity was reduced to 80% of the initial value, the life was finished. The trickle life characteristics of these batteries are shown in FIG.
[0020]
From the results shown in FIG. 1, by setting the negative electrode pore volume to 0.07 to 0.11 cm ³ / g, the Sn concentration in the positive electrode current collector was changed from 2.0, 2.5% by mass to 0.4%. It can be seen that good lifetime characteristics can be obtained even when the content is reduced to from mass% to 1.8 mass%. If a 0.05 cm ³ / g and a negative ultrafine pore volume decreased from 0.07 cm ³ / g, regardless of the Sn concentration in the positive electrode current collector, the life characteristics are deteriorated. It is presumed that this is because if the pore volume is reduced to a certain level or less, the reduction of the pore volume is promoted during the trickle life test, and the capacity reduction easily proceeds.
[0021]
<Example 2>
In Example 1, for the battery in which the Sn amount in the positive electrode current collector was 1.2 mass% and the pore volume of the negative electrode active material was 0.09 cm ³ / g, the valve opening pressure of the safety valve was changed from 2000 Pa to 15000 Pa. A trickle life test was conducted under the same conditions as in Example 1. The result is shown in FIG.
[0022]
From the results shown in FIG. 2, it can be seen that the trickle life tends to decrease when the valve opening pressure becomes higher than 11000 Pa. As the valve opening pressure increased, the trickle charge current during the trickle life test tended to increase, and the life decreased due to accelerated corrosion of the positive electrode current collector. This is presumably because the oxygen partial pressure in the battery increased due to the increase in the valve opening pressure, and the oxygen gas absorption reaction in the negative electrode was promoted.
[0023]
Even if the valve opening pressure is set lower than 4000 Pa, the trickle life is reduced. Such a battery has a large decrease in liquid during trickle charging as compared with other batteries, and the capacity decreases due to an increase in internal resistance due to a decrease in the amount of water in the electrolytic solution, leading to a lifetime. Accordingly, it is preferable to set the valve opening pressure to at least 4000 Pa or more. However, if the valve opening pressure is particularly set to 11000 Pa or less, an increase in trickle charge current can be further suppressed, and a battery having more excellent trickle life characteristics can be obtained. it can.
[0024]
【The invention's effect】
As described above, according to the configuration of the present invention, it is excellent while reducing the amount of expensive Sn added to the positive electrode current collector in the past in order to obtain excellent trickle life characteristics. It is possible to provide a control valve type lead storage battery having trickle life characteristics at low cost, which is extremely useful industrially.
[Brief description of the drawings]
FIG. 1 is a diagram showing the trickle life characteristics of the batteries of the present invention and the comparative example in Example 1. FIG. 2 is a diagram showing the trickle life characteristics of the batteries of the present invention and the comparative example in Example 2.

Claims

An electrode plate group comprising a positive electrode current collector made of a Pb-Sn alloy, a positive electrode plate having a positive electrode active material, a negative electrode current collector made of a Pb alloy, and a negative electrode plate having a porous negative electrode active material; In a control valve type lead-acid battery comprising a battery case for storing a group of plates and a lid that covers the opening of the battery case, and a safety valve that opens and closes by battery internal pressure on at least one of the battery case and the lid, the positive electrode current collector includes 0.4 wt% to 1.8 wt% of Sn, the pore volume per unit mass of the negative electrode active material (pore volume) to 0.07cm ^³ /g~0.11cm ³ / Control valve type lead acid battery characterized by being g.

The valve-operated lead-acid battery according to claim 1, wherein a valve opening pressure of the safety valve is set to 4000 Pa to 11000 Pa.