【考案の詳細な説明】[Detailed explanation of the idea]
産業上の利用分野
本考案は鉛蓄電池の改良に関するものであり、
特に太陽光発電用鉛蓄電池のように不完全な充電
状態で使用される鉛蓄電池に適用される。
従来技術とその問題点
鉛蓄電池の充放電反応は次式で表わされ、電解
液であるH2SO4の濃度は充放電により変化する。
Pbo2＋Pb＋2H2SO4放電
充電
2PbSO4＋2H2Ｏ
放電時には電解液中のSO4 2-が極板活物質に使
用されるため、電解液濃度は低下し、一方充電時
には極板からSO4 2-が放出されるため、電解液濃
度は上昇する。しかし充電時に極板から放出され
るSO4 2-は電解液中のSO4 2-より濃度が高いため
下方へ流下し、電池下部に留まりやすい。充電電
気量が放電電気量の約90％に達すると、極板より
ガスが発生し始め、このガスの発生により電解液
の攪拌が行なわれるが、充電が120％以下の場合、
攪拌効果が不十分で電解液濃度は均一にならず、
電池下部の電解液濃度は上部に比べて高くなる。
このような充放電を繰返すと、電池上部と下部に
おける電解液濃度差はますます拡大し極板の性能
劣化を招く。
これは放電時には電解液濃度の高い極板下部か
ら反応が開始されるのに対し、充電時には電解液
濃度の低い極板上部から反応が開始されるため、
放電時に極板下部に生成したPbSO4が、充電時に
完全にPbo2あるいはPbに戻らないことによるも
のである。特に負極板においては、極板下部に生
成したPbSO4は次第にその結晶が大きくなり、
120％以上の充電を行なつても完全にはPbには還
元されにくくなる。
太陽光発電に使用される鉛蓄電池は、その充電
が天候に左右されるため、不完全な充電状態が続
くことがあり、上述した電池上部と下部での電解
液濃度差が生じやすく、性能劣化の原因となりや
すい。この電解液の濃度差が生しる現象を解消す
るために、エアーポンプ等の攪拌装置を設けて電
解液を強制的に攪拌する方策や、電池の内圧上昇
を利用して電解液を循環させる方法が提案されて
いるが、攪拌装置や電池内部構造の複雑さのため
電池コストが高くなる。
考案の目的
本考案は上述の欠点に鑑みなされたものであ
り、寿命性能の優れた安価な鉛蓄電池を提供する
ことを目的とする。
考案の構成
本考案は上記目的を達成すべく、格子体下半分
の格子目の数を上半分の格子目の数の1.4倍以上
とした負極格子体を使用することを特徴とする鉛
蓄電池である。
実施例
以下本考案の一実施例を説明する。第１図は本
考案による鉛蓄電池の一実施例に用いる負極格子
体であり、下半分の横格子骨の間隔を上半分より
小さくし、下半分の格子目の数を多くしている。
第２図は従来の鉛蓄電池に使用されている負極格
子体を示す。第１図のように上半分と下半分の格
子目の数の異なる数種類の負極格子体を用いた
150AHの電池を組立て、下記のサイクル試験を
行なつた。
まず完全充電の状態から15Aで８時間放電を行
なつた後、15Aで６時間充電し、その後15Aで６
時間放電、15Aで６時間充電を11サイクル繰返し
た。この間は、不完全な充電状態での使用にあた
る。次に15Aで６時間放電を行なつた後15Aで10
時間充電を行なつた。この最後の放電での６時間
目の電圧および充電後の電池上部、下部における
電解液比重を測定し記録した。
前記パターンを繰返し、測定時における放電末
電圧が1.7V／セルを切つた時点を寿命とした。
第１表にこの結果を示した。
Industrial Application Field This invention relates to the improvement of lead-acid batteries.
This applies particularly to lead-acid batteries that are used in an incompletely charged state, such as lead-acid batteries for solar power generation. Prior art and its problems The charging and discharging reaction of a lead-acid battery is expressed by the following equation, and the concentration of H 2 SO 4 , which is an electrolytic solution, changes with charging and discharging. Pbo 2 +Pb+2H 2 SO 4Discharge and charge 2PbSO 4 +2H 2 O During discharge, SO 4 2- in the electrolyte is used as the active material of the electrode plate, so the electrolyte concentration decreases, while during charging, SO 4 2 is removed from the electrode plate. - is released, so the electrolyte concentration increases. However, the SO 4 2- released from the electrode plates during charging has a higher concentration than the SO 4 2- in the electrolyte, so it flows downward and tends to remain at the bottom of the battery. When the amount of charged electricity reaches approximately 90% of the amount of discharged electricity, gas begins to be generated from the electrode plates, and the electrolyte is stirred by the generation of this gas, but if the amount of charge is less than 120%,
The electrolyte concentration is not uniform due to insufficient stirring effect.
The electrolyte concentration at the bottom of the battery is higher than at the top.
When such charging and discharging are repeated, the difference in electrolyte concentration between the upper and lower parts of the battery further increases, leading to deterioration in the performance of the electrode plates. This is because during discharging, the reaction starts from the bottom of the plate where the electrolyte concentration is high, whereas during charging, the reaction starts from the top of the plate where the electrolyte concentration is low.
This is because PbSO 4 generated at the bottom of the electrode plate during discharge does not completely return to Pbo 2 or Pb during charging. Especially in the negative electrode plate, the crystals of PbSO 4 generated at the bottom of the electrode plate gradually become larger.
Even if it is charged to 120% or more, it will not be completely reduced to Pb. The charging of lead-acid batteries used in solar power generation depends on the weather, so they may remain incompletely charged for a long time, and the above-mentioned difference in electrolyte concentration between the top and bottom of the battery tends to occur, leading to performance deterioration. It is easy to cause this. In order to eliminate this phenomenon caused by the difference in the concentration of the electrolyte, measures are being taken to forcibly stir the electrolyte by installing a stirring device such as an air pump, or to circulate the electrolyte by utilizing the increase in internal pressure of the battery. Methods have been proposed, but the complexity of the stirring device and the internal structure of the battery increases the battery cost. Purpose of the invention The present invention was devised in view of the above-mentioned drawbacks, and an object of the present invention is to provide an inexpensive lead-acid battery with excellent life performance. Structure of the invention In order to achieve the above object, the present invention is a lead-acid battery characterized by using a negative electrode grid in which the number of grids in the lower half of the grid is 1.4 times or more than the number of grids in the upper half of the grid. be. Embodiment An embodiment of the present invention will be described below. FIG. 1 shows a negative electrode lattice body used in an embodiment of a lead-acid battery according to the present invention, in which the intervals between horizontal lattice bones in the lower half are smaller than those in the upper half, and the number of lattice meshes in the lower half is increased.
FIG. 2 shows a negative electrode grid used in a conventional lead-acid battery. As shown in Figure 1, several types of negative electrode grid bodies with different numbers of grid meshes in the upper and lower halves were used.
A 150AH battery was assembled and the following cycle test was conducted. First, from a fully charged state, discharge at 15A for 8 hours, then charge at 15A for 6 hours, then charge at 15A for 6 hours.
11 cycles of time discharge and 6 hour charging at 15A were repeated. During this time, the battery is used in an incompletely charged state. Next, discharge at 15A for 6 hours, and then discharge at 15A for 10
I charged it for an hour. The voltage at the 6th hour of this final discharge and the specific gravity of the electrolyte at the top and bottom of the battery after charging were measured and recorded. The above pattern was repeated, and the life span was defined as the point in time when the end-of-discharge voltage at the time of measurement fell below 1.7 V/cell. Table 1 shows the results.
【表】【table】
【表】
上表より明らかなように、負極格子体の下半分
の格子目の数を上半分の1.4倍以上にすると寿命
性能が大きく改善されることがわかる。また650
サイクル時における電池上部、下部における電解
液比重の差は、下半分の格子目の数が多いほど小
さく、寿命サイクル数と大きく関係している。こ
れは負極格子体の下部の格子目の数を多くするこ
とにより、極板下部での充電効率がよくなり電解
液濃度差が生じにくくなり寿命が改善されたもの
と思われる。
本実施例は上部の格子目の数を一定にして下部
の格子目の数を変えた例であるが、上部の格子目
を大きくして数を減らしてもよい。
考案の効果
以上に如く、本考案によれば、不完全な充電状
態で使用される鉛蓄電池での電解液濃度差の発生
が抑制され、鉛蓄電池の寿命向上につながるとと
もに特別な付属品を要しないため安価な鉛蓄電池
を提供できるので、その工業的価値は極めて大で
ある。[Table] As is clear from the table above, it can be seen that the life performance is greatly improved when the number of grids in the lower half of the negative electrode grid is 1.4 times or more that in the upper half. 650 again
The difference in electrolyte specific gravity between the upper and lower parts of the battery during cycling becomes smaller as the number of grids in the lower half increases, and is strongly related to the number of life cycles. This is thought to be because increasing the number of lattices at the bottom of the negative electrode grid improves charging efficiency at the bottom of the electrode plate, making it difficult for electrolyte concentration differences to occur and improving lifespan. Although this embodiment is an example in which the number of the upper grids is constant and the number of the lower grids is varied, the number may be reduced by increasing the number of the upper grids. Effects of the invention As described above, according to the invention, the occurrence of electrolyte concentration differences in lead-acid batteries used in an incompletely charged state is suppressed, leading to an extension of the lifespan of lead-acid batteries and the need for special accessories. Since it is possible to provide an inexpensive lead-acid battery because it does not contain carbon dioxide, its industrial value is extremely large.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は本考案の一実施例における鉛蓄電池の
負極格子体を示した図で、第２図は従来の鉛蓄電
池における負極格子体を示した図である。
FIG. 1 is a diagram showing a negative electrode grid of a lead-acid battery according to an embodiment of the present invention, and FIG. 2 is a diagram showing a negative electrode grid of a conventional lead-acid battery.