【０００１】
【発明の属する技術分野】本発明は劣化した鉛電池の再生方法に関するものである。
【０００２】
【従来の技術】従来、希硫酸を電解液とする鉛蓄電池において、電池の充電不足に伴い硫酸鉛の大型結晶が陰極に成長するのを防止するため、均等充電と称する低電流、長時間の充電を定期的に行なう対策が行なわれてきた。しかしながら、一旦陰極で硫酸鉛の大型結晶が成長すると、その結晶は通常の充電では容易には分解されず、電池容量の低下を防止する効果は限定的であった。また、陰極に硫酸鉛の大型結晶が成長する原因としては、陽極活物質を保持するグリッドに主として用いられているアンチモン２ないし６％と残部が鉛よりなる合金からアンチモンイオン（Ｓｂ３＋またはＳｂ５＋）が電解液中に溶出し、これが還元されて陰極に析出し、このアンチモンが析出した陰極の水素過電圧が著しく低下する為に、通常の充電条件でも陰極で水素の発生が起こりやすくなり、硫酸鉛の還元反応が不充分になり、残存する硫酸鉛が次第に成長するものと考えられる。この硫酸鉛の大型結晶を微細結晶に変化させる方法として、本発明者等は先に、電解液にポリビニルアルコール、ポリアクリル酸、リグニン等の有機ポリマーを添加する方法を提案した。しかしながらこれらの添加剤による方法では、対象とする電池の使用状態や、それに伴う劣化の状態に応じて効果の程度にばらつきが生ずるという問題があった。
【０００３】
【発明が解決しようとする課題】本発明は、劣化した鉛電池の陰極活物質の微構造が、放電条件により大きく変化し、その放電条件を選択することにより、陰極活物質の微構造を大幅に改良することができることを見出し、更にこの処理と添加剤を組合わせることにより、劣化した鉛電池を初期特性近くに迄ばらつき少なく再生できることを見出したものである。
【０００４】
【課題を解決するための手段】本発明は、鉛電池の電解液中にポリビニルアルコール、ポリアクリル酸、リグニンからなる群のうちの少なくとも一つの有機添加剤を加え、０．３Ｃ以上、好ましくは１Ｃ以上の放電率で該電池の公称容量の２％以上、好ましくは１０％以上の電気量を連続または断続して放電させる鉛電池の再生方法、および、鉛電池を０．３Ｃ以上、好ましくは１Ｃ以上の放電率で該電池の公称容量の２％以上、好ましくは１０％以上の電気量を連続または断続して放電させた後、電解液中にポリビニルアルコール、ポリアクリル酸、リグニンからなる群のうちの少なくとも一つの有機添加剤を加える鉛電池の再生方法である。
【０００５】本発明において、Ｃは対象とする電池の定格容量を分母とし、１時間当りの放電電気量を分子とする電流の大きさの放電率を意味し、例えば０．３Ｃとは、１時間当り、定格容量の３０％に相当する電気量を放電する電流の大きさの放電率を意味し、１Ｃとは、１時間当り、定格容量の１００％に相当する電気量を放電する電流の大きさの放電率をを意味する。本発明の放電処理は連続して行なうことが最も好ましいが、電池の発熱対策等が必要な場合には断続的に行なっても良い。また、電解液にポリビニルアルコール、ポリアクリル酸、リグニン等の有機添加剤を加える場合は、本発明者等が先に提案した特開２０００−１４９９８１号、特開２０００−２２３１４５号、特開２００１−３１３０６４号の方法を用いることができ、大電流放電処理と有機添加剤とを組合わせた本発明では有機添加剤単独の場合に比べて、その添加の効果が一層顕著で且つばらつきが少ない。また、電池の電解液中に有機添加剤を加え、０．３Ｃ以上、好ましくは１Ｃ以上の電流で該電池の公称容量の２％以上、好ましくは１０％以上の電気量を連続または断続して放電した後の鉛電池の電解液をアンチモンを実質的に含まない電解液と置換してもよい。更に、劣化した電池を、０．３Ｃ以上、好ましくは１Ｃ以上の電流で該電池の公称容量の２％以上、好ましくは１０％以上の電気量を連続または断続して放電した後の鉛電池の電解液を、アンチモンを実質的に含まず、且つ前記の有機添加剤を含む電解液と置換してもよい。
【０００６】本発明で用いる有機添加剤の量は、電解液中に０．００２重量％〜１重量％であることが好ましく、０．０２重量％〜０．２重量％の範囲で特に効果が大きい。
【０００７】
【作用】本発明の大電流、長時間放電と有機添加物との相乗効果について、以下詳細に説明する。
鉛電池の多くは自動車のエンジン始動用や電動フォークリフトの主電源として使われており、大電流放電が必要な自動車のエンジン始動時でも１Ｃないし１．５Ｃ程度の放電率で、その放電時間は数秒間であり、放電される電気量としては電池の公称容量の０．１％程度に過ぎない。また、電動フォークリフトの場合では、通常１回の充電で１シフトの作業を行なっており、０．１Ｃ〜０．２Ｃの放電率で公称容量の１００％近い放電を行なっていることになる。これらのいずれの場合でも、放電電気量が少なすぎるか、または、放電率が小さいため、陰極の硫酸鉛の結晶を微細化する効果は認められない。
こてに対して、本発明者は、大電流すなわち０．３Ｃ以上、好ましくは１Ｃ以上、更に好ましくは１．５Ｃ以上の放電率で該電池の公称容量の２％以上、好ましくは５％以上、更に好ましくは１０％ないし５０％の電気量を連続または断続して放電させると、陰極の硫酸鉛の結晶が明確に微細化することを見出した。更にその際、該電池の電解液中にポリビニルアルコール、ポリアクリル酸、リグニン等の有機添加剤を添加すると微細化が一層促進されること、および、電池の再生効果の指標となる完全充電時の電解液の比重についても、新品の電池の電解液に近い値にまで上昇することを見出した。また、これらの有機添加剤は大電流放電処理の後で電解液中に添加した場合でも、その後の完全充電時の電解液の比重の低下を防止する効果がある。
【０００８】
【実施例】
【実施例１】エンジン始動および一般電装品用電源として自動車に３年間使用した公称容量４０Ａｈの鉛電池（５時間率の容量は２５Ａｈ）を大自工業株式会社製ＳＬ−３型充電器で２０時間普通充電（充電電流約１．５Ａ）した際の電解液の比重は１．１９であった。この電池の電解液に５％のポリビニルアルコール水溶液を１セル当り５ミリリットル添加し、更に７２時間同じ充電器で普通充電した。この結果、電解液の比重は僅かに上昇し１．２３となった。この電池を６０Ａで１０分間放電した。この後、さらに同じ充電器で２０時間普通充電した。この結果、電解液の比重は１．３０にまで上昇した。この電池の放電特性は、６０Ａ放電で９Ｖの端子電圧になる迄の時間は１６分であり、十分な容量に再生された。
【０００９】
【実施例２】エンジン始動および一般電装品用電源として自動車に３年間使用して劣化したために廃棄された公称容量４０Ａｈの鉛電池について、電解液を新しい電解液と交換し、更に５％のポリビニルアルコール水溶液を１セル当り５ミリリットル添加し、２０時間１．８Ａで普通充電した。これを６０Ａで１５分間放電した。この電池を再度２０時間１．６Ａで普通充電した。この電池の電解液の比重は１．２８であり、１５０Ａ−５秒間の放電試験で、閉路電圧（ＣＣＶ）が１１．２Ｖを示し、実用上十分な性能に再生された。
【００１０】
【発明の効果】以上の説明から明らかな通り、本発明の方法によれば、大電流、長時間放電と有機添加物との相乗効果により、陰極の硫酸鉛の結晶が微細化され、これに伴い電解液の比重が顕著に上昇し、電池特性が著しく回復されるものである。[0001]
The present invention relates to a method for regenerating a deteriorated lead battery.
[0002]
2. Description of the Related Art Conventionally, in a lead-acid battery using dilute sulfuric acid as an electrolytic solution, a large current of lead sulfate is prevented from growing on a cathode due to insufficient charging of the battery. Measures have been taken to charge the battery periodically. However, once a large crystal of lead sulfate grows on the cathode, the crystal is not easily decomposed by ordinary charging, and the effect of preventing a decrease in battery capacity is limited. The reason why large crystals of lead sulfate grow on the cathode is that antimony ions (Sb 3+ or Sb 5+) are formed from an alloy composed mainly of 2 to 6% of antimony and the balance being lead, which is mainly used for the grid holding the anode active material. ) Is eluted into the electrolyte solution, which is reduced and deposited on the cathode, and the hydrogen overvoltage of the cathode on which antimony is deposited is significantly reduced, so that hydrogen is easily generated at the cathode even under normal charging conditions, and sulfuric acid is generated. It is considered that the reduction reaction of lead becomes insufficient and the remaining lead sulfate grows gradually. As a method for changing the large crystals of lead sulfate into fine crystals, the present inventors have previously proposed a method of adding an organic polymer such as polyvinyl alcohol, polyacrylic acid, or lignin to an electrolytic solution. However, the method using these additives has a problem that the degree of the effect varies depending on the use state of the target battery and the state of deterioration accompanying the use state.
[0003]
SUMMARY OF THE INVENTION According to the present invention, the microstructure of a cathode active material of a deteriorated lead battery is greatly changed depending on discharge conditions, and the microstructure of the cathode active material is greatly increased by selecting the discharge conditions. It has been found that by combining this treatment with an additive, a deteriorated lead battery can be regenerated with little variation to near the initial characteristics.
[0004]
According to the present invention, at least one organic additive selected from the group consisting of polyvinyl alcohol, polyacrylic acid, and lignin is added to the electrolyte of a lead battery, and the additive is added at a concentration of 0.3 C or more, preferably A method for regenerating a lead battery in which a quantity of electricity of 2% or more, preferably 10% or more of the nominal capacity of the battery is continuously or intermittently discharged at a discharge rate of 1C or more, and 0.3C or more, preferably A group consisting of polyvinyl alcohol, polyacrylic acid, and lignin in an electrolytic solution after continuously or intermittently discharging an amount of electricity of 2% or more, preferably 10% or more of the nominal capacity of the battery at a discharge rate of 1C or more. A method for regenerating a lead battery, wherein at least one organic additive is added.
In the present invention, C means a discharge rate of a magnitude of a current in which a rated capacity of a target battery is a denominator and a discharge electric quantity per hour is a numerator. The discharge rate is the magnitude of the current that discharges an amount of electricity corresponding to 30% of the rated capacity per hour, and 1C is the discharge rate of the amount of electricity that is equivalent to 100% of the rated capacity per hour. It means the magnitude of the discharge rate. The discharge treatment of the present invention is most preferably carried out continuously, but may be carried out intermittently when measures against heat generation of the battery are required. When organic additives such as polyvinyl alcohol, polyacrylic acid, and lignin are added to the electrolytic solution, JP-A-2000-149981, JP-A-2000-223145, and JP-A-2001-2001 proposed by the present inventors previously. The method of No. 313064 can be used, and in the present invention in which the large current discharge treatment and the organic additive are combined, the effect of the addition of the organic additive is more remarkable and has less variation than the case of using the organic additive alone. Further, an organic additive is added to the electrolyte of the battery to continuously or intermittently charge 2% or more, preferably 10% or more of the nominal capacity of the battery at a current of 0.3C or more, preferably 1C or more. The electrolyte of the lead battery after the discharge may be replaced with an electrolyte substantially not containing antimony. Further, the deteriorated battery is discharged at a current of 0.3 C or more, preferably 1 C or more, by continuously or intermittently discharging 2% or more, preferably 10% or more of the nominal capacity of the battery. The electrolyte may be replaced with an electrolyte substantially free of antimony and containing the above-mentioned organic additive.
[0006] The amount of the organic additive used in the present invention is preferably 0.002% by weight to 1% by weight in the electrolytic solution, and particularly effective in the range of 0.02% by weight to 0.2% by weight. large.
[0007]
The synergistic effect of the large current, long discharge and the organic additive of the present invention will be described in detail below.
Most lead batteries are used for starting the engine of automobiles or as the main power source of electric forklifts. Even when starting the engine of an automobile that requires large current discharge, the discharge rate is about 1C to 1.5C, and the discharge time is several times. Seconds, the amount of electricity discharged is only about 0.1% of the nominal capacity of the battery. In addition, in the case of an electric forklift, one shift operation is usually performed with one charge, and a discharge of about 100% of the nominal capacity is performed at a discharge rate of 0.1 C to 0.2 C. In any of these cases, since the amount of discharge electricity is too small or the discharge rate is small, the effect of refining the lead sulfate crystal of the cathode is not recognized.
On the other hand, the present inventor has found that a large current, that is, 0.3 C or more, preferably 1 C or more, and more preferably 1.5 C or more at a discharge rate of 2% or more, preferably 5% or more of the nominal capacity of the battery Further, it has been found that when the electric charge of 10% to 50% is discharged continuously or intermittently, the crystal of lead sulfate of the cathode is clearly refined. Further, at this time, the addition of an organic additive such as polyvinyl alcohol, polyacrylic acid, or lignin to the electrolyte of the battery further promotes miniaturization, and at the time of full charge, which is an indicator of the battery's regeneration effect. It was also found that the specific gravity of the electrolytic solution also increased to a value close to the electrolytic solution of a new battery. Further, even when these organic additives are added to the electrolytic solution after the high-current discharge treatment, there is an effect of preventing a decrease in the specific gravity of the electrolytic solution at the time of complete charging thereafter.
[0008]
【Example】
EXAMPLE 1 A lead-acid battery with a nominal capacity of 40 Ah (25-hour capacity at a 5-hour rate) used for a car for 3 years as a power source for engine starting and general electrical equipment was charged with a SL-3 type charger manufactured by Daijin Kogyo Co., Ltd. The specific gravity of the electrolytic solution after normal charging for a period of time (charging current of about 1.5 A) was 1.19. 5 ml of a 5% aqueous solution of polyvinyl alcohol was added to the electrolyte of the battery per cell, and the battery was normally charged for another 72 hours with the same charger. As a result, the specific gravity of the electrolyte slightly increased to 1.23. The battery was discharged at 60 A for 10 minutes. Thereafter, the battery was normally charged for another 20 hours using the same charger. As a result, the specific gravity of the electrolytic solution increased to 1.30. As for the discharge characteristics of this battery, it took 16 minutes to reach a terminal voltage of 9 V at a discharge of 60 A, and the battery was regenerated to a sufficient capacity.
[0009]
EXAMPLE 2 For a lead-acid battery having a nominal capacity of 40 Ah, which was discarded because it had been used for three years in an automobile as a power source for engine starting and general electric components, and was discarded, the electrolyte was replaced with a new electrolyte, and a further 5% of polyvinyl was added. 5 ml of an aqueous alcohol solution was added per cell, and the battery was normally charged at 1.8 A for 20 hours. This was discharged at 60 A for 15 minutes. The battery was again charged normally at 1.6 A for 20 hours. The specific gravity of the electrolytic solution of this battery was 1.28, and the discharge test at 150 A for 5 seconds showed a closed circuit voltage (CCV) of 11.2 V, which was reproduced to a practically sufficient performance.
[0010]
As is apparent from the above description, according to the method of the present invention, the lead sulfate crystal of the cathode is refined by the synergistic effect of the large current, the long-time discharge and the organic additive, Accordingly, the specific gravity of the electrolytic solution is significantly increased, and the battery characteristics are significantly restored.