JP4765190B2

JP4765190B2 - Control valve type lead acid battery

Info

Publication number: JP4765190B2
Application number: JP2001119277A
Authority: JP
Inventors: 章二堀江; 省三室地
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2001-04-18
Filing date: 2001-04-18
Publication date: 2011-09-07
Anticipated expiration: 2021-04-18
Also published as: JP2002313411A

Description

【０００１】
【発明の属する技術分野】
本発明は制御弁式鉛蓄電池に関するものである。
【０００２】
【従来の技術】
制御弁式鉛蓄電池は、充電時の酸素ならびに水素ガスの発生が極めて少なく、補水の必要がない等の利点を有し、様々な用途に広く用いられている。
【０００３】
しかしながら、充電時のガス発生を抑制するために、負極において酸素ガスを吸収する機構を設ける必要があるので、電解液の殆どを正極，負極ならびにセパレータに含浸させるようにした構成であった。そのため流動できる電解液が豊富な液式の鉛蓄電池に比べて、活物質量に対する電解液中の硫酸量が少ない構成となっている。従って、制御弁式鉛蓄電池は過放電されると、活物質よりも硫酸が先に消費されて、電解液が中性の水になってしまう。このような状態で放置されると、正極において格子体と活物質の界面に高抵抗の腐食層が生成することになり導電性が低下してしまい、充電できないか、または充電しても容量等の特性が回復しないといった課題がある。このような課題を解決する方法として、正極格子の表面に高濃度の錫を含有した層を設ける技術が開示されている。
【０００４】
ところで、制御弁式鉛蓄電池の容量等を向上する目的で、極板群下部のみを電解液に浸潰した構成が従来から提案されているが、このような構成の電池の場合、過放電されると正極格子表面に生成する腐食層は、電解液に浸潰した部分よりも電解液が浸潰されていない部分の方が高抵抗となっており、充電による回復性に差が見られることがわかってきた。
【０００５】
【発明が解決しようとする課題】
本発明は前記する問題点に鑑み、高濃度の錫を含有する層を正極格子の表面全体に均一に配設するのでなく、充電による電池容量等の特性の回復において、最も適切な位置でかつ特定な条件で効率的に高濃度の錫を含有する層を配設し、もって従来の課題を解決し、併せて高価な錫の使用量を合理的にすることを目的とするものである。
【０００６】
【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、請求項１に記載の発明は、正極板、負極板およびセパレータからなる極板群の一部が電解液に浸漬されるとともに、前記極板群の他の部分が電解液から露出した制御弁式鉛蓄電池であって、前記正極板は正極活物質と正極格子体を備え、前記正極格子体は鉛−錫合金もしくは鉛−錫−カルシウム合金もしくは鉛−カルシウム合金から構成されていて、前記正極格子体の表面の少なくとも一部に、錫の含有量が２．１質量％〜２１質量％の錫−鉛合金箔を用いて正極格子体に含まれる錫濃度よりも高濃度の錫を含有した高濃度錫含有層を設け、前記正極板の前記電解液に浸漬された部分における前記正極活物質量に対する前記高濃度錫含有層に含有される錫量の比率を比率Ａ、前記正極板の前記電解液から露出した部分における前記正極活物質量に対する前記高濃度錫含有層に含有される錫量の比率を比率Ｂとした場合において、前記比率Ａを０．００３質量％〜０．０３質量％とし、かつ比率Ａ＜比率Ｂとすることを示すものである。
【０００８】
【発明の実施の形態】
正極格子体は、例えば鉛−錫合金または鉛−錫−カルシウム合金または鉛−カルシウム合金を圧延加工することで連続したシート状とし、これに複数のスリットを入れて引き伸ばす所謂エキスパンド加工によって網目状に展開することによって形成される。
【０００９】
本発明は、図１に示すように、鉛−錫合金または鉛−錫−カルシウム合金または鉛−カルシウム合金をシート状に圧延加工する際、上記鉛合金シート１の錫濃度よりも高濃度であって２．１質量％〜２１質量％の錫を含む鉛−錫合金からなる連続した箔２を表面に配設して、ともに圧延加工することにより、正極格子体の表面に高濃度の錫を含有する高濃度錫含有層を備えることができる。さらに、これをエキスパンド加工する際、鉛合金シートの幅方向においてスリットの間隔を変化させて網目状に展開することで、正極板の活物質量に対する格子体表面層の錫量の比率を正極板の上下方向で変化させることができる。すなわち図２に示すように、電解液に浸潰される部分に相当する鉛合金シートの部位に入れるスリット間隔、例えばＷ１よりも、電解液から露出した部分に相当するスリット間隔、例えばＷ２を広くすることにより、電解液に浸潰された部分よりも電解液から露出した部分における正極活物質量に対する格子体表面層の錫量の比率を高くした正極板３が得られる。
【００１０】
さらに正極格子体表面の含錫層の形成方法については溶射等、種々の方法も用いることができる。さらに正極格子の電解液の浸潰された部分と電解液から露出した部分とで活物質量に対する錫量を変化させる手法として含錫層の厚みを変化させたり、濃度を変化させることも可能であるが、表面に含錫層を形成した鉛シートをエキスパンド加工して正極格子を得る際に切幅を電解液から露出した部分を電解液に浸潰された部分よりも大きく構成する方が簡便に得ることができる。
【００１１】
また、本発明の効果を得るために電解液に浸潰された部分における正極活物質量に対する格子体の表面層の錫量の比率を少なくとも０．００３質量％以上に構成する必要がある。但し０．３質量％を超えて多量としてもそれ以上の効果は得られないので、この比率を０．００３質量％〜０．３質量％とする必要がある。
【００１２】
このようにして得られた正極板３と負極板４およびセパレータ５を用いて、図３に示すように、極板群の一部が電解液６に浸潰された制御弁式鉛畜電池を構成する。
【００１３】
また、セパレータ５に関しては活物質よりも電解液の浸透速度が大きいものを用いることが好ましい。このような構成にすれば電解液から露出したセパレータ５中の電解液量は比較的多くなるので活物質量に対する錫量を多くしたことと相まって過放電時の回復性をさらに改善することができる。
【００１４】
【実施例】
次に本発明の効果について実施例をもって示す。
【００１５】
図１のように、連続的に鋳造した１０ｍｍ厚の鉛−カルシウム０．０７質量％−錫０．５質量％合金の表面に、厚み０．２ｍｍの錫７質量％−鉛合金の箔２を配設して圧延し、厚み１．０ｍｍの鉛合金シート１を作製し、これをエキスパンド加工して正極板を得た。この際、鉛合金シートへのスリット間隔を電解液に浸潰される部分（すなわち正極板の下部に対応する部分）よりも電解液から露出した部分（すなわち正極板の上部に対応する部分）を広くして作製した正極板２種類と、スリット間隔を均一にして作製した正極板および電解液に浸潰される部分を電解液から露出した部分よりも広くして作製した正極板の４種類を準備した。なお、正極板１枚当たりの活物質量ならびに錫７質量％−鉛合金箔の含有量は、すべての種類の正極板で同一である。
【００１６】
上記２種類の正極板と負極板ならびにセパレータをそれぞれ組み合わせて、セル当たり正極板５枚，負極板６枚からなる極板群とし、極板群の一部を電解液に浸潰させた構成の公称電圧１２Ｖ容量４８Ａｈの制御弁式鉛蓄電池を表１のように２種類作製した。
【００１７】
これらの電池について、次のような過放電放置試験を実施した。４０℃雰囲気にて１０Ωの抵抗負荷を接続して１ヵ月間放置した後、開路状態で２週間放置した。その後、充電回復性を評価するため、１４Ｖにて定電圧充電を４時間実施した後の電池容量を測定した。その試験結果を表１に示す。なお、比率Ａは、正極板の電解液に浸潰された部分における正極活物質量に対する正極格子体の表面層に含有される錫量の比率を示しており、比率Ｂは、正極板の電解液から露出した部分における正極活物質量に対する正極格子体の表面層に含有される錫量の比率を示している。
【００１８】
【表１】

【００１９】
表１のように、本発明例１および本発明例２、すなわちいずれも比率Ａ＜比率Ｂの電池は、他の従来例の電池、すなわち比率Ａ＝比率Ｂならびに比率Ａ＞比率Ｂと比較して正極格子体表面層の錫量は同一であるにもかかわらず、本発明例１および２の方が過放電放置後の充電回復性に優れていることが明らかである。これは、電解液に浸潰した部分に比べて、電解液が浸潰されていない部分では、過放電に伴う硫酸の消費が早期に進むことで電解液が中性になりやすいことが考えられる。このため、正極格子体表面に生成する腐食層は、電解液に浸潰した部分よりも電解液が浸潰されていない部分の方が高抵抗となるが、上記の本発明例のように、劣化を受けやすい部分に高濃度の錫層を効率的に配設することで、充電回復性が向上したものと推察される。
【００２０】
【表２】

【００２１】
次に、錫の含有量を０．７質量％，２．１質量％，７質量％，２１質量％，３５質量％と変えた錫−鉛合金箔を用いて、前述の本発明例と同様に表２に示すような制御弁式鉛蓄電池を各々作製した。これら５種類の電池について上記と同様に過放電放置後の充電回復性を容量回復率によって評価した。その結果を図４に示す。比率Ａが０．００３質量％よりも少なくなると容量回復率は低下し、一方、０．０３質量％を超えても容量回復率は殆ど変化がなかった。これらのことから、高価な錫の使用量を考慮すると、効果的な充電回復性が得られる範囲として、錫−鉛合金箔における錫の含有量を２．１質量％〜２１質量％とすることで、比率Ａを０．００３質量％〜０．０３質量％とする必要がある。
【００２２】
【発明の効果】
以上のように、本発明によれば、極板群の一部が電解液に浸潰された構成の制御弁式鉛蓄電池において、過放電放置による充電回復性の劣化を受けやすい部分の正極格子体に高濃度の錫を効率的に配設することで、低コスト且つ過放電回復性に優れた制御弁式鉛蓄電池を得ることが可能となる。
【図面の簡単な説明】
【図１】錫−鉛合金の箔を付与した鉛合金シートの圧延加工を示す説明図
【図２】本発明における一実施の形態の正極板の正面図
【図３】極板群ならびに電解液の構成を示す電池の断面略図
【図４】比率Ａと容量回復率の関係を示す図
【符号の説明】
１鉛合金シート
２高濃度錫を含んだ鉛合金の箔
３正極板
４負極板
５セパレータ
６電解液
Ｗ１，Ｗ２スリット間隔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control valve type lead acid battery.
[0002]
[Prior art]
The control valve type lead-acid battery has advantages such as generation of oxygen and hydrogen gas at the time of charging being extremely small and no need for rehydration, and is widely used for various applications.
[0003]
However, since it is necessary to provide a mechanism for absorbing oxygen gas in the negative electrode in order to suppress gas generation during charging, the configuration is such that most of the electrolyte is impregnated in the positive electrode, the negative electrode, and the separator. For this reason, the amount of sulfuric acid in the electrolytic solution relative to the amount of the active material is small compared to a liquid type lead storage battery rich in electrolytic solution that can flow. Accordingly, when the control valve type lead-acid battery is overdischarged, sulfuric acid is consumed earlier than the active material, and the electrolyte becomes neutral water. If left in such a state, a high-resistance corrosive layer is formed at the interface between the lattice and the active material in the positive electrode, resulting in a decrease in conductivity. There is a problem that the characteristics of these do not recover. As a method for solving such a problem, a technique for providing a layer containing a high concentration of tin on the surface of a positive electrode lattice is disclosed.
[0004]
By the way, for the purpose of improving the capacity and the like of the control valve type lead-acid battery, a configuration in which only the lower part of the electrode plate group is immersed in an electrolytic solution has been proposed in the past. Then, the corrosion layer generated on the surface of the positive electrode grid has a higher resistance in the portion where the electrolyte solution is not submerged than in the portion submerged in the electrolyte solution, and there is a difference in recoverability due to charging. I understand.
[0005]
[Problems to be solved by the invention]
In view of the above-mentioned problems, the present invention does not dispose a layer containing high-concentration tin uniformly over the entire surface of the positive electrode grid, but at the most appropriate position in restoring characteristics such as battery capacity by charging. The object is to efficiently arrange a layer containing high-concentration tin under specific conditions, thereby solving the conventional problems and rationalizing the amount of expensive tin used.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, the invention according to claim 1 is characterized in that a part of the electrode plate group including the positive electrode plate, the negative electrode plate, and the separator is immersed in an electrolyte solution, and the other part of the electrode plate group. Is a valve-regulated lead-acid battery exposed from the electrolyte, wherein the positive electrode plate includes a positive electrode active material and a positive electrode grid, and the positive electrode grid is a lead-tin alloy, a lead-tin-calcium alloy, or a lead-calcium alloy. From the tin concentration contained in the positive electrode lattice body using a tin-lead alloy foil having a tin content of 2.1 mass% to 21 mass% on at least a part of the surface of the positive electrode lattice body. Providing a high-concentration tin-containing layer containing high-concentration tin, and the ratio of the amount of tin contained in the high-concentration tin-containing layer to the amount of the positive electrode active material in the portion of the positive electrode plate immersed in the electrolyte Ratio A, exposed from the electrolyte solution of the positive electrode plate And when the ratio of tin content contained in the high concentration of tin-containing layer with respect to the positive active material amount in the portion and the ratio B, and the ratio A was 0.003 wt% to 0.03 wt%, and the ratio This indicates that A <ratio B.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The positive electrode grid is formed into a continuous sheet by rolling, for example, a lead-tin alloy, a lead-tin-calcium alloy, or a lead-calcium alloy. Formed by unfolding.
[0009]
The present invention, as shown in FIG. 1, a lead - tin alloy or lead - tin - calcium alloy or lead - when rolling calcium alloy into a sheet, met a concentration higher than the tin concentration of the lead alloy sheet 1 A continuous foil 2 made of a lead-tin alloy containing 2.1% by mass to 21% by mass of tin is disposed on the surface, and rolled together to form high concentration tin on the surface of the positive electrode grid. A high-concentration tin-containing layer can be provided. Furthermore, when this is expanded, the ratio of the amount of tin in the lattice surface layer to the amount of active material of the positive electrode plate is changed to a positive electrode plate by changing the slit interval in the width direction of the lead alloy sheet and expanding it in a mesh shape. Can be changed in the vertical direction. That is, as shown in FIG. 2, the slit interval corresponding to the portion exposed from the electrolytic solution, for example, W2 is made wider than the slit interval, for example, W1, which is inserted into the portion of the lead alloy sheet corresponding to the portion immersed in the electrolytic solution. As a result, the positive electrode plate 3 is obtained in which the ratio of the amount of tin in the lattice surface layer to the amount of the positive electrode active material in the portion exposed from the electrolytic solution is higher than the portion immersed in the electrolytic solution.
[0010]
Further, various methods such as thermal spraying can be used as a method for forming the tin-containing layer on the surface of the positive electrode lattice. Furthermore, the thickness of the tin-containing layer can be changed or the concentration can be changed as a method of changing the amount of tin with respect to the amount of active material between the portion of the positive electrode grid where the electrolyte is immersed and the portion exposed from the electrolyte. However, when the lead sheet with the tin-containing layer formed on the surface is expanded to obtain a positive electrode grid, it is easier to configure the width of the exposed part from the electrolyte than the part that is immersed in the electrolyte. Can get to.
[0011]
Further, it is necessary to configure the ratio of the tin content of the surface layer of the grid for the positive electrode active material amount in the immersion collapsed portion in the electrolytic solution in order to obtain the effect of the present invention to at least 0.003 mass% or more. However, even if the amount exceeds 0.3% by mass, no further effect is obtained, so this ratio needs to be 0.003% to 0.3% by mass.
[0012]
Using the positive electrode plate 3, the negative electrode plate 4, and the separator 5 obtained in this way, as shown in FIG. 3, a control valve type lead live battery in which a part of the electrode plate group is immersed in the electrolytic solution 6. Constitute.
[0013]
Moreover, regarding the separator 5, it is preferable to use a separator having a larger permeation rate of the electrolytic solution than the active material. With such a configuration, the amount of the electrolytic solution in the separator 5 exposed from the electrolytic solution becomes relatively large, so that the recoverability at the time of overdischarge can be further improved in combination with the increased amount of tin with respect to the amount of active material. .
[0014]
【Example】
Next, effects of the present invention will be described with examples.
[0015]
As shown in FIG. 1, a foil 2 of 0.2 mm thick tin 7 wt% -lead alloy is formed on the surface of a 10 mm thick lead-calcium 0.07 wt% -tin 0.5 wt% alloy continuously cast. It arrange | positioned and rolled, the lead alloy sheet 1 of thickness 1.0mm was produced, and this was expanded, and the positive electrode plate was obtained. At this time, the portion exposed from the electrolyte (that is, the portion corresponding to the upper portion of the positive electrode plate) is wider than the portion where the slit interval to the lead alloy sheet is immersed in the electrolyte (that is, the portion corresponding to the lower portion of the positive electrode plate). Four types were prepared: a positive electrode plate prepared by two steps, a positive electrode plate manufactured with a uniform slit interval, and a positive electrode plate manufactured by making the portion immersed in the electrolytic solution wider than the portion exposed from the electrolytic solution. . In addition, the amount of active material per positive electrode plate and the content of 7% by mass of tin-lead alloy foil are the same for all types of positive electrode plates.
[0016]
Each of the two types of positive electrode plate, negative electrode plate, and separator is combined to form an electrode plate group consisting of five positive electrode plates and six negative electrode plates per cell, and a part of the electrode plate group is immersed in an electrolyte solution. Two types of control valve type lead storage batteries having a nominal voltage of 12 V and a capacity of 48 Ah were prepared as shown in Table 1.
[0017]
These batteries were subjected to the following overdischarge leaving test. A 10 Ω resistive load was connected in a 40 ° C. atmosphere and left for 1 month, and then left open for 2 weeks. Then, in order to evaluate charge recovery property, the battery capacity after carrying out the constant voltage charge at 14V for 4 hours was measured. The test results are shown in Table 1. The ratio A indicates the ratio of the amount of tin contained in the surface layer of the positive electrode grid body to the amount of the positive electrode active material in the portion of the positive electrode plate immersed in the electrolytic solution, and the ratio B indicates the electrolysis of the positive electrode plate. The ratio of the amount of tin contained in the surface layer of the positive electrode grid body to the amount of the positive electrode active material in the portion exposed from the liquid is shown.
[0018]
[Table 1]

[0019]
As shown in Table 1, Example 1 and Example 2 of the present invention, that is, both batteries having a ratio A <ratio B are compared with other conventional batteries, that is, ratio A = ratio B and ratio A> ratio B. In spite of the same amount of tin in the positive electrode grid surface layer, it is apparent that Examples 1 and 2 of the present invention are superior in charge recovery after being left overdischarged. This is because the electrolyte solution tends to become neutral due to the early consumption of sulfuric acid associated with overdischarge in the portion where the electrolyte solution is not immersed, compared to the portion immersed in the electrolyte solution. . For this reason, the corrosion layer generated on the surface of the positive electrode grid body has a higher resistance in the portion where the electrolytic solution is not crushed than in the portion crushed in the electrolytic solution. It is inferred that the charge recovery is improved by efficiently disposing a high-concentration tin layer in a portion that is susceptible to deterioration.
[0020]
[Table 2]

[0021]
Next, using the tin-lead alloy foil in which the tin content was changed to 0.7% by mass, 2.1% by mass, 7% by mass, 21% by mass, and 35% by mass, similar to the above-described example of the present invention. Control valve type lead acid batteries as shown in Table 2 were prepared. For these five types of batteries, the charge recovery property after being left overdischarged was evaluated by the capacity recovery rate in the same manner as described above. The result is shown in FIG. When the ratio A was less than 0.003% by mass, the capacity recovery rate decreased. On the other hand, when the ratio A exceeded 0.03% by mass, the capacity recovery rate hardly changed. From these facts, considering the amount of expensive tin used, the tin content in the tin-lead alloy foil should be 2.1 mass% to 21 mass% as a range in which effective charge recovery is obtained. Therefore , the ratio A needs to be 0.003% to 0.03% by mass.
[0022]
【The invention's effect】
As described above, according to the present invention, in the control valve type lead storage battery having a configuration in which a part of the electrode plate group is immersed in the electrolyte, a portion of the positive electrode grid that is susceptible to deterioration in charge recovery due to overdischarge. By efficiently disposing high-concentration tin on the body, it is possible to obtain a control valve type lead-acid battery that is low in cost and excellent in overdischarge recovery.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a rolling process of a lead alloy sheet provided with a tin-lead alloy foil. FIG. 2 is a front view of a positive electrode plate according to an embodiment of the present invention. Fig. 4 is a schematic cross-sectional view of a battery showing the configuration of Fig. 4. Fig. 4 is a diagram showing the relationship between the ratio A and the capacity recovery rate.
DESCRIPTION OF SYMBOLS 1 Lead alloy sheet 2 Lead alloy foil containing high concentration tin 3 Positive electrode plate 4 Negative electrode plate 5 Separator 6 Electrolytic solution W1, W2 Slit space

Claims

A control valve type lead storage battery in which a part of an electrode plate group consisting of a positive electrode plate, a negative electrode plate and a separator is immersed in an electrolyte solution, and the other part of the electrode plate group is exposed from the electrolyte solution, Comprises a positive electrode active material and a positive electrode grid, and the positive electrode grid is composed of a lead-tin alloy, a lead-tin-calcium alloy, or a lead-calcium alloy, and at least part of the surface of the positive electrode grid , A high-concentration tin-containing layer containing a tin concentration higher than the tin concentration contained in the positive electrode grid is provided using a tin-lead alloy foil having a tin content of 2.1 mass% to 21 mass%, and the positive electrode The ratio of the amount of tin contained in the high-concentration tin-containing layer to the amount of the positive electrode active material in the portion immersed in the electrolytic solution of the plate is A, and the positive electrode active in the portion of the positive electrode plate exposed from the electrolytic solution High concentration of tin In the case where the ratio of tin content contained in the layer and the ratio B, the ratio A was 0.003 wt% to 0.03 wt%, and the ratio A <valve-regulated, characterized in that the ratio B Lead acid battery.