JP4812386B2 - Method for producing lead-acid battery - Google Patents

Description

本発明は、鉛蓄電池特に制御弁式鉛蓄電池の製造方法に関するものである。   The present invention relates to a method for producing a lead storage battery, particularly a control valve type lead storage battery.

無停電電源システム（以下ＵＰＳという）などのスタンバイユースに使用される制御弁式鉛蓄電池（以下単に電池という）は、通常は電池の自己放電を補うため、常時微小な電流でフロート充電される。 A control valve type lead-acid battery (hereinafter simply referred to as a battery) used for standby use such as an uninterruptible power supply system (hereinafter referred to as UPS) is usually float-charged with a very small current at all times in order to compensate for the self-discharge of the battery.

フロート充電による電池寿命の低下は、正極格子の腐食、活物質と格子の密着性低下、電解液減少による内部抵抗の増大などが主な原因である。 The main reasons for the decrease in battery life due to float charging are corrosion of the positive electrode grid, decrease in adhesion between the active material and the grid, and increase in internal resistance due to decrease in electrolyte.

フロート充電時には実質的に自己放電分以上の電流が流れるため、正極格子の腐食を促進し、これに伴う水消費が増大する。また充電電流が多すぎると、腐食とこれに伴う水消費量が多くなることと、水分解が促進されること、および水分解により正極から発生した酸素ガス量も多くなるので、負極での再結合反応に伴う電池温度の上昇を招き、更なるフロート電流の上昇が起こる。この結果、電池寿命に重大な悪影響を与えてしまう。 During float charging, a current substantially equal to or greater than the self-discharge flows, which promotes corrosion of the positive grid and increases water consumption associated therewith. If the charging current is too high, corrosion and the accompanying water consumption increase, water decomposition is accelerated, and the amount of oxygen gas generated from the positive electrode due to water decomposition increases. The battery temperature increases due to the binding reaction, and the float current further increases. As a result, the battery life is seriously adversely affected.

ＵＰＳなどのスタンバイユース用の電池は、フロート充電電流を低減させるため、および正極に比べて負極の利用率が高いことから、正極に対する負極の活物質量は少なく設定されている。更に一般的に負極は正極に対し化成効率が優れているので、初期の充電で正極の未化成部分が多くても負極の化成はほぼ終了している場合が多い。 A battery for standby use such as UPS is set to have a smaller amount of active material of the negative electrode with respect to the positive electrode because the float charging current is reduced and the utilization factor of the negative electrode is higher than that of the positive electrode. Furthermore, since the negative electrode generally has better conversion efficiency than the positive electrode, the formation of the negative electrode is almost completed even if there are many unformed parts of the positive electrode in the initial charge.

電池を組み立てる前の極板を希硫酸が入ったタンク内で化成する化成工程では、化成時間効率向上の目的で初期の充電で大きな電流を流し、化成効率が低下するにつれて段階的に充電電流を小さくする段別充電が行なわれている。 In the chemical conversion process in which the electrode plate before the battery is assembled is formed in a tank containing dilute sulfuric acid, a large current is supplied at the initial charge for the purpose of improving the chemical conversion time efficiency, and the charging current is gradually increased as the chemical conversion efficiency decreases. Step-by-step charging is performed.

この様に初期の充電で大きい電流を流しているので、極板活物質の比表面積は大きくなりやすい。同じ温度なら化成時の充電電流が大きいほど比表面積は大きくなり、充電電流が小さいほど比表面積は小さくなる傾向がある。そしてこの傾向は比較的化成効率の良い負極は、初期の大きい電流での充電によりほぼ化成が終了するので顕著に現れる。 As described above, since a large current flows in the initial charge, the specific surface area of the electrode plate active material tends to increase. At the same temperature, the specific surface area tends to increase as the charging current during formation increases, and the specific surface area tends to decrease as the charging current decreases. This tendency is noticeable in the negative electrode having a relatively high chemical conversion efficiency because the chemical conversion is almost completed by charging with a large initial current.

充電電流が大きくなると温度が上昇し比表面積は小さくなると考えられるが、タンク内での化成の場合は、電池を組み立てた液入り電池で行なう電槽化成に比べて希硫酸の量が多く、放熱もしやすいため、電流を大きくしたときの温度上昇による負極比表面積の低減効果は少ない。電槽化成の場合は充電電流の大小にもよるが、タンク内化成に比べ放熱性が悪いため温度上昇がしやすく、負極の比表面積も小さくなる傾向がある。 If the charging current increases, the temperature will rise and the specific surface area will decrease.However, in the case of chemical conversion in the tank, the amount of dilute sulfuric acid is larger than in the case of battery formation using a liquid battery assembled with a battery. If it is easy, the effect of reducing the negative electrode specific surface area due to the temperature rise when the current is increased is small. In the case of battery case formation, although it depends on the magnitude of the charging current, the heat dissipation is worse than in-tank formation, so the temperature tends to rise and the specific surface area of the negative electrode tends to be small.

従来のタンク内化成での充電条件では負極の比表面積が大きくなり、従って、これを組立て電池とした場合に負極の分極が小さくなり、フロート充電中に正極から発生した酸素を負極で吸収しやすくなるのでフロ−ト充電電流は大きくなる。このため、電池の寿命は一般的には電槽化成電池より短くなる傾向がある。ただし、電槽化成電池は注液後に電解液である希硫酸がペーストと反応するため、化成までの放置時間が長くなると硫酸濃度が著しく低下し、高率放電タイプなどの極板間がショートピッチな電池では濃度低下により硫酸鉛の溶解度が上昇する。この状態で化成をするとセパレータに溶解した硫酸鉛が還元されデンドライト状に成長し短絡の原因となる場合がある。 Under the conventional charging conditions in the tank formation, the specific surface area of the negative electrode is large. Therefore, when this is used as an assembled battery, the polarization of the negative electrode is small, and oxygen generated from the positive electrode during float charging is easily absorbed by the negative electrode. Therefore, the float charging current is increased. For this reason, the lifetime of the battery generally tends to be shorter than that of the battery case chemical battery. However, in battery case conversion batteries, the diluted sulfuric acid, which is the electrolyte solution, reacts with the paste after the injection, so the sulfuric acid concentration decreases significantly when the standing time until the formation is prolonged, and the high pitch discharge type and other electrode plates have a short pitch. In a new battery, the solubility of lead sulfate increases as the concentration decreases. If chemical conversion is performed in this state, lead sulfate dissolved in the separator may be reduced to grow in a dendrite shape, which may cause a short circuit.

電池の長寿命化のため従来から、正極格子を厚くして腐食代を増やす、フロート電流低減のため、負極活物質にオイルや脂肪酸などを一定量添加すること（特許文献１、２）や、負極活物質用の鉛粉に含まれる水分量を鉛粉質量に対して０．７質量％とすること（特許文献３）が提案されている。
特開平10-208745号公報 特開平10-208746号公報 特開2003-331833号公報 Conventionally, to increase battery life by increasing the positive electrode lattice to increase the life of the battery, to reduce the float current, to add a certain amount of oil or fatty acid to the negative electrode active material (Patent Documents 1 and 2), It has been proposed that the amount of water contained in the lead powder for the negative electrode active material is 0.7% by mass with respect to the mass of the lead powder (Patent Document 3).
Japanese Patent Laid-Open No. 10-208745 Japanese Patent Laid-Open No. 10-208746 JP 2003-331833 A

しかしこれら特許文献に記載の方法では、添加物を入れるためその分コスト増になることや、鉛粉製造用ミル内に供給する空気の相対湿度を３０ＲＨ％以下に制御しなければならない等新たな設備を導入する必要がありコスト増となるなどの問題がある。
近年、スタンバイユースの制御弁式鉛蓄電池には２５℃環境で１０年以上の長寿命の要求が多く、寿命特性改善のために腐食減量を考慮した正極格子の鉛量増加などで対処されているが、エネルギー密度およびコストの観点から好ましくない。タンク内化成した極板を用いた電池でも、電槽化成電池と同等の長寿命を達成するためには更なるフロート電流低減が必要となる。 However, in the methods described in these patent documents, since the additive is added, the cost is increased accordingly, and the relative humidity of the air supplied into the mill for producing lead powder must be controlled to 30 RH% or less. There is a problem that it is necessary to introduce equipment and the cost increases.
In recent years, control valve type lead-acid batteries for standby use have many demands for a long life of 10 years or more in an environment of 25 ° C., and have been dealt with by increasing the lead amount of the positive electrode grid considering corrosion weight loss in order to improve the life characteristics. However, it is not preferable from the viewpoint of energy density and cost. Even in the case of a battery using an electrode plate formed in the tank, it is necessary to further reduce the float current in order to achieve a long life equivalent to that of the battery case conversion battery.

上記課題を解決するため、正、負極板を組み立てる前に希硫酸が入ったタンクの中で化成する化成工程の初期の充電電流密度を、負極の活物質量に対し１０〜４０ｍA/ｇとし、充電電気量を負極理論容量に対して２０％以上とする鉛蓄電池の製造方法を提供する。 In order to solve the above problems, the initial charging current density in the chemical conversion step that is formed in a tank containing dilute sulfuric acid before assembling the positive and negative electrode plates is set to 10 to 40 mA / g with respect to the active material amount of the negative electrode, Provided is a method for producing a lead storage battery in which the amount of charged electricity is 20% or more of the theoretical capacity of the negative electrode.

（作用）
タンク内化成初期の基本的な活物質の構造形成期に、充電電流密度を負極活物質量に対し１０〜４０ｍA／gとすることにより負極比表面積が減少する。１０ｍＡ／ｇ未満では化成に時間が掛かり過ぎ、４０ｍＡ／ｇ超の電流では負極比表面積の減少効果が少ない。更にこの充電電流密度での充電は、負極理論容量の２０％以上の充電電気量が必要で、これ以下では十分な効果を得ることが出来ない。そして負極比表面積を小さくすることで、フロート充電時の負極の分極が増大するので、充電電流を小さくすることができる。 (Function)
The negative electrode specific surface area is reduced by setting the charging current density to 10 to 40 mA / g with respect to the amount of the negative electrode active material during the basic active material structure formation stage in the early stage of the formation in the tank. If it is less than 10 mA / g, it takes too much time to form, and if the current exceeds 40 mA / g, the effect of reducing the negative electrode specific surface area is small. Furthermore, charging at this charging current density requires a charge electricity amount of 20% or more of the theoretical capacity of the negative electrode, and a sufficient effect cannot be obtained below this amount. By reducing the specific surface area of the negative electrode, the polarization of the negative electrode during float charging increases, so that the charging current can be reduced.

本発明によれば、タンク内で化成する化成工程での初期の充電電流を適性に制御することのみで従来の電極板を変更することなくフロート充電電流を抑えられ、正極格子の腐食を低減し、経済的に高性能電池を提供することができる。   According to the present invention, the float charging current can be suppressed without changing the conventional electrode plate only by appropriately controlling the initial charging current in the chemical conversion process in the tank, and the corrosion of the positive grid can be reduced. High performance battery can be provided economically.

本発明の実施例を従来例、比較例とともに説明する。常法により作成した正、負極板をこれらセパレータを介して交互に積層する組み立て前に、以下に述べる各種条件で希硫酸水溶液を入れたタンク内で、正、負極板を隙間を開けて対峙させて化成をおこない、その後、所定枚数を組み合わせて交互に積層して極板群とし、これを６個のセル室を有する電槽の各セル室内に収納して電池を組み立て、１２V、２０時間率容量が２Ahの各電池を作成した。 Examples of the present invention will be described together with conventional examples and comparative examples. Before assembling the positive and negative plates prepared in a conventional manner alternately through these separators, the positive and negative plates are opposed to each other in a tank containing dilute sulfuric acid solution under various conditions described below. Then, a predetermined number of sheets are combined and stacked alternately to form an electrode plate group, which is housed in each cell chamber of a battery case having six cell chambers, and a battery is assembled. Each battery having a capacity of 2 Ah was prepared.

実施例は化成初期の充電電流を負極活物質量に対し１０、２０、３０、４０ｍA／gの電流密度とし、従来例としては化成初期の充電電流密度を５０、６０ｍA／g、比較例では同様に５ｍA／ｇとした。いずれの場合も初期の充電電流密度での充電電気量が負極活物質の理論容量比で１００％に達する時点まで充電した。ついで第２段階の充電は負極活物質に対する充電電流密度を４０ｍA／gとし、正極活物質の理論容量比で２２０％まで化成を行なった。   In the examples, the charging current at the initial stage of chemical conversion was set to 10, 20, 30, 40 mA / g with respect to the amount of the negative electrode active material, and the charging current density at the initial stage of chemical conversion was 50, 60 mA / g as in the conventional example. 5 mA / g. In either case, charging was performed until the amount of electricity charged at the initial charging current density reached 100% in terms of the theoretical capacity ratio of the negative electrode active material. Next, in the second stage charge, the charge current density with respect to the negative electrode active material was set to 40 mA / g, and the chemical conversion was performed up to 220% in terms of the theoretical capacity ratio of the positive electrode active material.

各種化成条件で作製した負極板の比表面積（ｍ²／ｇ）はＢＥＴ法で測定し、各種化成条件で作製した正、負極板で組み立てた電池のフロート充電性能は、電池周囲温度６０℃、充電電圧１３．６５Vの条件でフロート充電電流を測定した。また、電池の放電特性試験は、負極比表面積の影響が想定される常温および低温の高率放電特性として、電池周囲温度は２５℃、−５℃、放電電流は３ＣＡ（６Ａ）、終止電圧は９．６V(１．６Ｖ／セル)の条件とした。 The specific surface area (m ² / g) of the negative electrode plate prepared under various chemical conversion conditions was measured by the BET method, and the float charging performance of the battery assembled with the positive and negative electrode plates prepared under various chemical conversion conditions was as follows. The float charging current was measured under the condition of a charging voltage of 13.65V. In addition, the battery discharge characteristics test was conducted at a normal temperature and low temperature high rate discharge characteristics where the influence of the negative electrode specific surface area is assumed. The battery ambient temperature is 25 ° C., −5 ° C., the discharge current is 3 CA (6 A), and the end voltage is The condition was 9.6 V (1.6 V / cell).

表１に本発明品の実施例１〜４、従来例１、２および比較例１の負極比表面積と６０℃フロート充電電流および２５℃と−５℃におけるそれぞれの３ＣＡ放電特性を示す。従来例１、２に比べて実施例１〜４、比較例１は負極比表面積が減少しており、６０℃フロート充電電流も減少した。しかし、放電電流３ＣＡの高率放電特性は常温（２５℃）、低温(−５℃)ともにほとんど差がない。負極の比表面積が減少しても放電特性の影響が出なかったのは、負極の利用率が高かったためと考えられる。 Table 1 shows the negative electrode specific surface area, 60 ° C. float charging current, and 3CA discharge characteristics at 25 ° C. and −5 ° C. of Examples 1 to 4, Examples 1 and 2 of the present invention, and Comparative Example 1. Compared to Conventional Examples 1 and 2, Examples 1-4 and Comparative Example 1 had a reduced negative electrode specific surface area, and a 60 ° C. float charge current also decreased. However, the high rate discharge characteristics of the discharge current 3CA are almost the same at both normal temperature (25 ° C.) and low temperature (−5 ° C.). The reason why the discharge characteristics were not affected even when the specific surface area of the negative electrode decreased was considered to be because the utilization factor of the negative electrode was high.

比較例１では従来例に比べて６０℃充電電流が低減できているが、化成時の初期充電電流が非常に小さく、化成時間が長くかかりすぎるため、現実的には実施例１〜４の範囲が良い。   In Comparative Example 1, the 60 ° C. charging current can be reduced as compared with the conventional example, but the initial charging current at the time of formation is very small and the formation time is too long. Is good.

次に各電池のフロート寿命試験を行ない、残存電池容量、正極格子腐食量を評価した結果を表２に示す。寿命試験は各電池の周囲温度６０℃、充電電圧１３．６５Ｖとしてフロート充電を６ヶ月間継続した。１ヶ月毎に放電電流０．２５CA（０．５A）、周囲温度２５℃、終止電圧１０．２Vの条件で容量試験を行なった。寿命試験６ヵ月後に各電池を解体し、正極格子の腐食部分をアルカリ性マントニット溶液で溶かし、質量源から腐食量を求めた。 Next, a float life test of each battery was performed, and the results of evaluating the remaining battery capacity and the positive electrode lattice corrosion amount are shown in Table 2. In the life test, float charging was continued for 6 months at an ambient temperature of 60 ° C. and a charging voltage of 13.65 V. A capacity test was conducted every month under the conditions of a discharge current of 0.25 CA (0.5 A), an ambient temperature of 25 ° C., and a final voltage of 10.2 V. Each battery was disassembled after 6 months of the life test, and the corroded portion of the positive electrode grid was dissolved with an alkaline mantonit solution, and the amount of corrosion was determined from a mass source.

従来例１、２に対し、実施例１〜４はフロート充電電流が小さいため、正極格子の腐食量も少なく、容量試験における放電時間が長いことがわかる。   Compared with the prior art examples 1 and 2, since the float charging currents in Examples 1 to 4 are small, the amount of corrosion of the positive electrode grid is small, and the discharge time in the capacity test is long.

次いで化成電気量の影響を調査した。初期の充電電流密度は負極活物質量に対して一定の３０ｍA／gとし、その充電電気量を負極理論容量に対し０〜１５０％まで変化させた。その後に第２充電として、負極活物質量に対する充電電流密度を一定の６０ｍA／gとし、正極の理論容量比で２２０％まで化成を行なった。これらの極板を用いて、同様に１２V、２０時間率容量が２Ahの電池を作製した。   Next, the influence of chemical electricity was investigated. The initial charge current density was constant 30 mA / g with respect to the negative electrode active material amount, and the charge electricity amount was changed from 0 to 150% with respect to the negative electrode theoretical capacity. Thereafter, as the second charge, the charge current density with respect to the amount of the negative electrode active material was set to a constant 60 mA / g, and the chemical conversion was performed up to 220% in terms of the theoretical capacity ratio of the positive electrode. Using these electrode plates, similarly, a battery having 12 V and a 20 hour capacity of 2 Ah was produced.

これらの電池を上記と同様の条件で各電池性能の評価を行なった。各充電電気量における負極比表面積と６０℃フロート充電電流、各温度での高率放電容量の測定結果を表３に示す。また夫々の電池のフロート寿命試験６ヵ月後の容量試験と正極格子腐食量の測定結果を表４に示す。   These batteries were evaluated for battery performance under the same conditions as described above. Table 3 shows the measurement results of the negative electrode specific surface area, the 60 ° C. float charging current, and the high rate discharge capacity at each temperature for each charge amount. Table 4 shows the capacity test after 6 months of the float life test of each battery and the measurement results of the positive electrode lattice corrosion amount.

本発明に係る負極理論容量に対する化成充電電気量が２０％以上では、負極活物質の比表面積の大幅な低下が認められる。これに伴い電池の初期性能の低下なしにフロート充電電流の低減、および良好な寿命性能を得られることが判明した。化成工程でのこの充電電気量は多いほど電池特性に有利と考えられるが、工業的には４０％から１２０％が望ましい。 When the amount of chemical charging electricity with respect to the theoretical capacity of the negative electrode according to the present invention is 20% or more, a significant decrease in the specific surface area of the negative electrode active material is observed. As a result, it has been found that the float charging current can be reduced and good life performance can be obtained without lowering the initial performance of the battery. It is considered that the larger the amount of charged electricity in the chemical conversion process, the more advantageous the battery characteristics, but 40% to 120% is desirable industrially.

これらの結果より、タンク内で行う化成では初期充電電流密度を負極活物質量に対し１０〜４０ｍA/gとし、その初期充電電流密度で流す電気量は負極理論容量の２０％以上で実施するとフロート充電電流の低減が可能となり、電池の長寿命化を図ることができる。

From these results, in the chemical conversion carried out in the tank, the initial charge current density is 10 to 40 mA / g with respect to the amount of the negative electrode active material, and the amount of electricity flowing at the initial charge current density is floated when carried out at 20% or more of the negative electrode theoretical capacity. The charging current can be reduced, and the life of the battery can be extended.

Claims (1)

鉛蓄電池の極板を組み立てる前に希硫酸液のタンク内で化成する化成工程において、初期の充電電流密度を負極活物質量に対し１０〜４０ｍA／gとすると共に、この充電電流密度での充電電気量を負極理論容量に対し２０％以上充電することを特徴とする鉛蓄電池の製造方法。
In the chemical conversion process of forming in the dilute sulfuric acid tank before assembling the electrode plate of the lead storage battery, the initial charging current density is set to 10 to 40 mA / g with respect to the amount of the negative electrode active material, and charging is performed at this charging current density. A method for producing a lead-acid battery, wherein the amount of electricity is charged by 20% or more of the theoretical capacity of the negative electrode.