JP2004253324A

JP2004253324A - Positive electrode lattice body of lead acid storage battery and lead acid storage battery using the same

Info

Publication number: JP2004253324A
Application number: JP2003044553A
Authority: JP
Inventors: Michio Kurematsu; 道男榑松
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2003-02-21
Filing date: 2003-02-21
Publication date: 2004-09-09
Anticipated expiration: 2023-02-21
Also published as: JP4374867B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode plate lattice which has solved problems of deformation of lattice occurring at the corrosion of the positive electrode and degradation of lifetime of the battery caused by fall-off of the active material, and a lead acid storage battery having superior life characteristics. <P>SOLUTION: This is a lattice body of the lead acid storage battery which comprises an expanded mesh developing a lead alloy sheet in mesh of a net, and a current collector part at the upper frame provided in contact with this expanded mesh, and in which this current collector part is installed offset from the center line of the expanded mesh. It comprises a tilting part in which the portion corresponding to the expanded mesh end part from the current collector ear member of the upper frame to the center line direction is reduced in the height dimension (h) as it approaches the expanded mesh end part from the current collector part, and a parallel part in which the height dimension (h) is constant provided corresponding to the expanded mesh end part, and a coupling part for coupling the tilting part and the parallel part by a curved line is provided. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、鉛蓄電池の極板格子の形状に関するものである。
【０００２】
【従来の技術】
鉛蓄電池の極板は鉛もしくは鉛合金の格子体に活物質を充填した構成を有している。この格子体としては溶融鉛を鋳型中で凝固させた鋳造格子体や圧延鉛合金シートにスリットを千鳥状に形成し、このスリットを展開したエキスパンド格子体が用いられている。エキスパンド格子体は格子体を薄型化でき、生産性に優れることから、広く用いられている。
【０００３】
このエキスパンド格子体６０１は図６に示したようにエキスパンド網目６０２と一体に下枠骨６０３と上枠骨６０４が形成されており、この上枠骨６０４に集電耳部６０５を備えている。このようなエキスパンド格子体６０１は鋳造格子とは異なり、左右両側部に枠骨を有しておらず、さらには格子中骨形状の自由度が低いことから、集電効率の面で鋳造格子体と比較して不利であり、格子体による電圧降下もより大きく、電池の放電電圧を低下させる一因となっていた。
【０００４】
さらにエキスパンド格子体６０１を正極に用いた場合、エキスパンド格子体６０１は酸化腐食を受け、枠骨を有していない２辺の延長方向、すなわち、図６の矢印Ａ方向へ伸びる。そして伸びたエキスパンド格子体６０１は負極と短絡し、急激に電池の容量が低下するという問題があった。
【０００５】
これらの格子体による電圧低下を抑制し、かつ腐食による伸びを抑制するため、従来から上枠骨、特に上枠骨の集電部分を太くあるいは大きくすることが有効であることが知られている（例えば、特許文献１参照）。
【０００６】
また、集電耳に補強部を設けるとともに、格子体が伸びた状態で発生する上枠骨の屈曲点位置を規定しているものもある（例えば、特許文献２参照）。この特許文献２では格子体が伸びた場合に上枠骨の変形を屈曲点で優先的に発生させ、この屈曲点の位置を負極棚下に設けることによって、上枠骨が変形しても、負極端と接触短絡しない構造とするものである。
【０００７】
ところが、このような屈曲点を設定した場合、格子体を構成する鉛合金組成によっては、この屈曲点での応力集中が急激に進行することがわかってきた。特に、Ｓｎ濃度を１．２質量％以上添加したＰｂ−Ｓｎ−Ｃａ合金は、合金自体の耐食性と強度が向上するために、正極に用いることによって電池の寿命性能を改善することができる。ところが、このような高耐食性・高強度の合金を用いると屈曲点に集中する応力の絶対値も大きくなり、ある時点で急激に上枠骨の変形が進行し、これに対応して電池の容量も急激に低下するという課題があった。このような急激な容量低下は変形した上枠骨の下部に存在する活物質が格子の変形に追随できずに脱落することによって発生していた。
【０００８】
正極から脱落した活物質に関して、正極板を袋状セパレータに包皮した場合、脱落活物質は袋状セパレータ内に留まるため、電池容量が低下する他は特性上、大きな影響を及ぼさない。ところが、正極を袋状セパレータに収納しない、特に負極板を袋状セパレータに収納した電池ではこれらの脱落活物質は電槽下部に蓄積する。特に自動車用電池のような、振動が避けられない用途で用いられる電池では、振動によって脱落活物質が電解液中を浮遊し、負極に付着することによって還元し、負極上に析出する。このような析出物が次第に成長し、正極と短絡するといった問題があった。
【０００９】
【特許文献１】
特開昭６０−３００５７号公報（第２８８頁、第４図）
【特許文献２】
特開平８−２０３５３３号公報（第５頁、第３図）
【００１０】
【発明が解決しようとする課題】
本発明は前記したような鉛蓄電池において、正極の腐食時に発生する格子変形と活物質脱落による電池の寿命低下という課題を解決し、耐食性に優れた極板格子と優れた寿命特性を有した鉛蓄電池を提供するものである。
【００１１】
【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、鉛合金シートを網状に展開して成るエキスパンド網目を備え、このエキスパンド網目に接して設けた上枠骨に集電部を備えるとともに、前記集電部を前記エキスパンド網目の中心線から偏芯して設けた鉛蓄電池の格子体であって、前記上枠骨の前記集電耳から前記中心線方向に前記エキスパンド網目端部に対応した部分は前記集電部から前記エキスパンド網目端部に近接するにしたがい高さ寸法（ｈ）を減少させた傾斜部と、前記エキスパンド網目端部に対応して設けた高さ寸法（ｈ）を一定とした平行部を備え、前記傾斜部と前記平行部の間を曲線で連結する連結部を設けたことを特徴とするものである。
【００１２】
また、本発明の請求項２に係る発明は、請求項１の鉛蓄電池の極板格子において、連結部を円弧形状としたことを特徴とするものである。
【００１３】
また、本発明の請求項３に係る発明は、請求項２の鉛蓄電池の極板格子において、傾斜部の上端の延長線と平行部の上端の延長線とがなす角をθ（°）、前記円弧形状の半径をＲ（ｍｍ）としたときに、前記θを１０〜４０°とし、かつ前記θと前記Ｒとの関係をＲ≧１０^（２−θ^／４５）とするものである。
【００１４】
さらに、本発明の請求項４に係る発明は、請求項１、２もしくは３の鉛蓄電池の極板格子において、鉛合金シート中のＳｎ濃度が１．２質量％以上、２．０質量％以下であることを特徴とするものである。
【００１５】
また、本発明の請求項５に係る発明は、請求項１、２、３もしくは４の極板格子を少なくとも正極板に用いたことを特徴とする鉛蓄電池を示すものである。
【００１６】
そして、本発明の請求項６に係る発明は請求項５の鉛蓄電池において、負極板を収納した袋状セパレータと正極板とを用いた極板群を備えたことを特徴とする鉛蓄電池を示すものである。
【００１７】
【発明の実施の形態】
本発明の実施の形態による鉛電池の正極格子を図面を用いて説明する。
【００１８】
本発明による鉛蓄電池の正極格子１００は図１に示したように、集電耳部１０２を一体に設けた上枠骨１０１を有している。そして上枠骨１０１には活物質（図示せず）を充填するためのエキスパンド網目１０３を一体に設け、さらにこのエキスパンド網目１０３には極板底部に対応する下枠骨１０４を有している。
【００１９】
エキスパンド網目１０３はＰｂ−Ｃａ−Ｓｎ合金といった鉛合金シートに千鳥状のスリットを形成し、このスリットを展開することにより形成される。集電耳部１０２はエキスパンド網目１０３の中心線（図１における線Ｌ）から偏芯して設けられている。
【００２０】
上枠骨１０１の集電耳部１０２から中心線Ｌ方向にエキスパンド網目１０３の端部までの部分１０４）は、集電耳部１０２からエキスパンド網目１０３の端部に近接するに従い高さ寸法（ｈ）を減少させていく傾斜部１０５と、エキスパンド網目１０３の端部から設けた高さ寸法（ｈ´）を一定とした平行部１０６を有している。
【００２１】
本発明では傾斜部１０５と平行部１０６との間に連結部１０７が設けられている。連結部１０７は平行部１０６と傾斜部１０５との間を滑らかな曲線で結ぶ。連結部１０７の曲線形状は円弧形状とすれば良い。連結部１０７を円弧形状とする場合、傾斜部１０５の延長線１０８と平行部の延長線１０９とのなす角度をθ（°）とし、連結部１０７の円弧形状の半径をＲ（ｍｍ）とした時に、Ｒとθとの関係を式（１）の関係を満たすよう構成する。また、前記θを１０〜４０°とする。
【００２２】
Ｒ≧１０^（２−θ^／４５） …式（１）
その後、正極格子１００に活物質（図示せず）を充填し、熟成乾燥して正極板とし、この正極板を用いることによって本発明の鉛蓄電池を得ることができる。
【００２３】
上記の本発明の構成を用いることによって正極格子１００が腐食しても上枠骨の変形を抑制する。この変形抑制によって変形した上枠骨による正極−負極間の短絡と正極活物質の脱落による容量低下を抑制することができる。
【００２４】
また、正極活物質の脱落を抑制できるため、従来、脱落活物質を保持するために正極を袋状セパレータに収納していた構成に代えて、負極板を袋状セパレータに収納した構成を採用することができる。負極板を袋状セパレータに収納する構成では腐食によって変形する正極格子が袋状セパレータ底部を破損するといった正極板を袋状セパレータに収納することによって発生する問題がない。
【００２５】
したがって、本発明では負極板を袋状セパレータに収納した構成をとれば、正極活物質の脱落抑制と、袋状セパレータの底部破損抑制を両立して達成することができる。
【００２６】
さらに、本発明の正極格子１００を構成する鉛合金の組成としてＳｎ濃度が１．２０質量％以上である、Ｐｂ−Ｃａ−Ｓｎ合金を用いることが好ましい。なお、本発明ではＣａの濃度を規定するものではないが、エキスパンド加工時の加工性を考慮してＣａ濃度を０．０４質量％〜０．１０質量％の範囲とする。
【００２７】
また、本発明ではＳｎ濃度の上限値を規定するものではないが、Ｃａと同様、Ｓｎ濃度の増加によって、エキスパンド網目に亀裂や切断が生じるため、Ｓｎ濃度の上限を２．０質量％以下とすることが好ましい。
【００２８】
正極格子１００に用いるＰｂ−Ｃａ−Ｓｎ合金中のＳｎ濃度を１．２０質量％以上とすることにより、Ｐｂ−Ｃａ−Ｓｎ合金の耐食性は向上し、正極格子の腐食進行を抑制でき、その分、鉛蓄電池を長寿命化できる点で有利である。ところがＰｂ−Ｃａ−Ｓｎ合金の引張り強度も向上するので、正極格子が腐食を受けた場合には正極格子への応力は増加する。前記した特許文献２のように、変形の屈曲点をある点に設定した場合、この屈曲点に応力が集中する。Ｓｎ濃度が１．２０質量％以上のＰｂ−Ｃａ−Ｓｎ合金ではＳｎ濃度が１．２質量％未満のものに比較して、この集中した応力値が急激に増大する。これにより、正極格子体の変形は急激に進行し、突然容量が低下して、電池が使用不能となる。
【００２９】
本発明の構成では上記のようなＳｎ濃度のＰｂ−Ｃａ−Ｓｎ合金を使用した場合でも上枠骨に加わる応力を分散させることにより、上枠骨の急激な変形を抑制することができる。
【００３０】
【実施例】
次に、本発明の実施例を説明する。
【００３１】
▲１▼実施例１
Ｐｂ−０．０５質量％Ｃａ−１．８質量％Ｓｎ合金の圧延シートを用いてロータリーエキスパンド法により図２に示すようなエキスパンド網目２０１を作成した。次にエキスパンド網目２０１に活物質を充填し、図２の破線で示した切断線２０２で打抜き、単一の極板とした後、熟成乾燥をおこなって、未化成の正極板とした。
【００３２】
本実施例においては、前記した本発明の実施の形態の正極格子のθおよびＲの値を種々の組み合わせで変化させることにより、本発明例の正極格子体と比較例の正極格子体を作成した。そしてこれらの正極板を用いて表１に示す８０Ｄ２６型（ＪＩＳＤ５３０１）の始動用鉛蓄電池を作成した。なお、本実施例では負極板を微孔性ポリエチレンシートで作成された袋状セパレータに収納し、正極板と組み合わせて極板群を作成した。
【００３３】
【表１】

【００３４】
これらの電池を４０℃雰囲気中で１４．８Ｖの定電圧で４週間連続充電し、充電終了後に電池を分解して、図３に示したように、正極格子３００の上枠骨３０１の上方向への変形量（ｄ）を測定した。そしてそれぞれの電池の変形量（ｄ）について電池４の変形量に対する比率を求め、その結果を変形量比ｄ´として表１に示した。
【００３５】
次に図４に縦軸にＲとθとの関係と変形量比（ｄ´）を示した。図４に示した結果から、θが１０〜４０°の範囲内であり、かつ下式（１）の範囲内での領域内で変形量比を極めて低く抑制できることがわかる。
【００３６】
Ｒ≧１０^（２−θ^／４５） … 式（１）
（但し、Ｒの単位はｍｍであり、かつ１０°≦θ≦４０°）
▲２▼実施例２
次に実施例１の表１に示した電池９および電池２２に関して鉛合金シート中のＳｎ濃度と、袋状セパレータに収納する極板の極性を変化させた電池を作成した。これらの電池を表２に示す。
【００３７】
【表２】

【００３８】
これら表２に示した電池について充電と放電とを繰返して行う寿命サイクル試験を行った。試験条件は充電を４０℃雰囲気中で１４．８Ｖの定電圧充電を１週間、放電を２５℃雰囲気中で３００Ａで５秒間の定電流放電とした。これらの充電と放電を繰返して行い、放電５秒目の電圧が７．２Ｖまで低下した時点を寿命サイクル数とした。これらの寿命試験の結果を図５に示す。
【００３９】
図５に示した結果から、正極格子に用いたＰｂ−Ｃａ−Ｓｎ合金中のＳｎ濃度が１．２０質量％以上の領域では比較例の電池は急激に寿命低下している。一方、本発明例の電池ではＳｎが１．２０質量％以上であっても良好な寿命特性を示す。
【００４０】
中でも負極板を袋状セパレータに収納した本発明例の電池では極めて優れた寿命特性を示した。
【００４１】
比較例の電池でＳｎ濃度を１．２０質量％以上としたものは正極格子の上枠骨の変形が一箇所に集中し、その点で上枠骨が折り曲がった状態となっていた。一方、本発明例ではこのようなＳｎ濃度であっても上枠骨の変形は一箇所に集中せず、変形が分散していた。また、Ｓｎ濃度を１．２０質量％未満に低下させていくにしたがい、上枠骨が一箇所で集中的に折れ曲がる変形から上枠骨全体が変形する状態に変化した。また、Ｓｎ濃度低下にしたがい、寿命サイクル数自体も低下した。したがって、本発明のよればＳｎ濃度が１．２０質量％以上の領域においても極めて良好な寿命特性を得ることができる。
【００４２】
また、特に本発明では正極格子の変形抑制により、脱落活物質量も抑制できるので、従来のような正極板を袋状セパレータに収納する必要がない。したがって、正極板を袋状セパレータに収納した時の問題点、すなわち、袋状セパレータの底部の破損による正極−負極間の短絡という問題を回避できる。
【００４３】
【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、腐食時に発生する格子変形と活物質脱落による電池寿命の低下という課題を解決し、長寿命な鉛蓄電池を提供できることから、工業上、極めて有用である。
【図面の簡単な説明】
【図１】本発明による極板格子を示す図
【図２】エキスパンド網目を示す図
【図３】上枠骨の変形量測定位置を示す図
【図４】Ｒ、θ別の変形量比ｄ´を示す図
【図５】寿命試験結果を示す図
【図６】従来のエキスパンド格子体を示す図
【符号の説明】
１００正極格子
１０１上枠骨
１０２集電耳部
１０３エキスパンド網目
１０４（上枠骨の）部分
１０５傾斜部
１０６平行部
１０７連結部
１０８延長線
１０９延長線
２０１エキスパンド網目
２０２切断線
３００正極格子
３０１上沸骨
６０１エキスパンド格子体
６０２エキスパンド網目
６０３下枠骨
６０４上枠骨
６０５集電耳部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the shape of an electrode grid of a lead storage battery.
[0002]
[Prior art]
The electrode plate of the lead storage battery has a configuration in which a grid of lead or a lead alloy is filled with an active material. As the lattice body, an expanded lattice body in which slits are formed in a zigzag pattern on a cast lattice body or a rolled lead alloy sheet obtained by solidifying molten lead in a mold and the slits are developed. Expanded lattices are widely used because they can reduce the thickness of the lattice and are excellent in productivity.
[0003]
As shown in FIG. 6, the expanded lattice body 601 is formed with a lower frame bone 603 and an upper frame bone 604 integrally with the expanded mesh 602, and the upper frame bone 604 is provided with a current collecting ear 605. Unlike the cast lattice, such an expanded lattice body 601 does not have frame bones on both left and right sides, and furthermore, has a low degree of freedom in the shape of a bone in the lattice. However, the voltage drop due to the grid body is larger, which is one of the causes of lowering the discharge voltage of the battery.
[0004]
Further, when the expanded lattice body 601 is used as a positive electrode, the expanded lattice body 601 is subjected to oxidative corrosion and extends in the extending direction of two sides having no frame bone, that is, in the direction of arrow A in FIG. Then, the expanded expanded lattice body 601 is short-circuited with the negative electrode, and there is a problem that the capacity of the battery is rapidly reduced.
[0005]
It is conventionally known that it is effective to make the current collecting part of the upper frame bone, particularly the upper frame bone thicker or larger, in order to suppress the voltage drop due to these lattice bodies and suppress the elongation due to corrosion. (For example, see Patent Document 1).
[0006]
In addition, there is a method in which a reinforcing portion is provided on a current collecting ear and a bending point position of an upper frame bone generated when the lattice body is extended is defined (for example, see Patent Document 2). In Patent Document 2, when the lattice body is elongated, the deformation of the upper frame bone is preferentially generated at the bending point, and the position of the bending point is provided below the negative electrode shelf, so that even if the upper frame bone is deformed, the negative The structure does not cause a contact short circuit with an extreme.
[0007]
However, when such an inflection point is set, it has been found that stress concentration at this inflection point rapidly progresses depending on the lead alloy composition constituting the lattice. In particular, a Pb-Sn-Ca alloy to which a Sn concentration of 1.2% by mass or more is added can improve the corrosion resistance and strength of the alloy itself, so that the battery life performance can be improved by using the Pb-Sn-Ca alloy as a positive electrode. However, the use of such a high corrosion-resistant and high-strength alloy also increases the absolute value of the stress concentrated at the bending point, and at a certain point, the deformation of the upper frame bone progresses rapidly, and the capacity of the battery correspondingly increases. Also had the problem of rapidly decreasing. Such a sharp decrease in capacity has been caused by the active material present below the deformed upper frame bone falling off without being able to follow the deformation of the lattice.
[0008]
When the positive electrode plate is encased in a bag-shaped separator with respect to the active material dropped from the positive electrode, the dropped active material remains in the bag-shaped separator, so that there is no significant effect on characteristics except for a decrease in battery capacity. However, in a battery in which the positive electrode is not housed in the bag-shaped separator, particularly in a battery in which the negative electrode plate is housed in the bag-shaped separator, these fallout active materials accumulate in the lower part of the battery case. In particular, in batteries used in applications where vibration is unavoidable, such as automobile batteries, the falling active material floats in the electrolytic solution due to the vibration, and is reduced by attaching to the negative electrode, and is deposited on the negative electrode. There is a problem that such precipitates gradually grow and short-circuit with the positive electrode.
[0009]
[Patent Document 1]
JP-A-60-30057 (page 288, FIG. 4)
[Patent Document 2]
JP-A-8-203533 (page 5, FIG. 3)
[0010]
[Problems to be solved by the invention]
The present invention solves the problem that the lead storage battery described above has a problem that the battery life is shortened due to lattice deformation and active material falling off at the time of corrosion of the positive electrode, and a lead plate having excellent corrosion resistance and lead having excellent life characteristics. It is intended to provide a storage battery.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problem, the invention according to claim 1 of the present invention includes an expanded mesh formed by expanding a lead alloy sheet into a net shape, and a current collector is provided on an upper frame bone provided in contact with the expanded mesh. And a grid body of a lead storage battery in which the current collector is provided eccentrically from the center line of the expanded mesh, wherein the end of the expanded mesh is arranged in the direction of the center line from the current collecting ear of the upper frame bone. The portion corresponding to the portion has an inclined portion having a reduced height dimension (h) as it approaches the end portion of the expanded mesh from the current collecting portion, and a height dimension provided corresponding to the end portion of the expanded mesh ( h) is provided with a parallel portion, and a connecting portion for connecting the inclined portion and the parallel portion with a curved line is provided.
[0012]
According to a second aspect of the present invention, in the electrode grid of the lead-acid battery of the first aspect, the connecting portion is formed in an arc shape.
[0013]
The invention according to claim 3 of the present invention provides the electrode plate grid of the lead-acid battery according to claim 2, wherein an angle formed by an extension of the upper end of the inclined portion and an extension of the upper end of the parallel portion is θ (°), When the radius of the arc shape is R (mm), the angle θ is 10 to 40 °, and the relationship between the angle θ and the angle R is R ≧ 10 ⁽²⁻ θ ^{/ 45)} .
[0014]
Furthermore, the invention according to claim 4 of the present invention is the electrode plate grid of the lead storage battery according to claim 1, wherein the Sn concentration in the lead alloy sheet is 1.2% by mass or more and 2.0% by mass or less. It is characterized by being.
[0015]
Further, the invention according to claim 5 of the present invention is directed to a lead storage battery characterized in that at least the positive electrode plate uses the electrode plate grid of

claim

1, 2, 3 or 4.
[0016]
According to a sixth aspect of the present invention, there is provided the lead-acid battery according to the fifth aspect, further comprising an electrode group including a bag-shaped separator accommodating the negative electrode plate and a positive electrode plate. Things.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
A positive electrode grid of a lead battery according to an embodiment of the present invention will be described with reference to the drawings.
[0018]
As shown in FIG. 1, the positive electrode grid 100 of the lead-acid battery according to the present invention has an upper frame bone 101 integrally provided with a current collecting ear 102. The upper frame bone 101 is provided integrally with an expanded mesh 103 for filling an active material (not shown), and the expanded mesh 103 has a lower frame bone 104 corresponding to the bottom of the electrode plate.
[0019]
The expanded mesh 103 is formed by forming a zigzag slit in a lead alloy sheet such as a Pb-Ca-Sn alloy and expanding the slit. The current collecting ear 102 is provided eccentrically from the center line (line L in FIG. 1) of the expanded mesh 103.
[0020]
The portion 104 of the upper frame bone 101 from the collecting ear 102 to the end of the expanded mesh 103 in the direction of the center line L becomes closer to the end of the expanding mesh 103 from the collecting ear 102 to the height (h). ), And a parallel portion 106 provided from the end of the expanded mesh 103 and having a constant height dimension (h ′).
[0021]
In the present invention, a connecting portion 107 is provided between the inclined portion 105 and the parallel portion 106. The connecting portion 107 connects the parallel portion 106 and the inclined portion 105 with a smooth curve. The curved shape of the connecting portion 107 may be an arc shape. When the connecting portion 107 has an arc shape, the angle between the extension line 108 of the inclined portion 105 and the extension line 109 of the parallel portion is θ (°), and the radius of the arc shape of the connecting portion 107 is R (mm). Sometimes, the relationship between R and θ is configured to satisfy the relationship of Expression (1). The angle θ is set to 10 to 40 °.
[0022]
R ≧ 10 ^(2- θ ^{/ 45)} Equation (1)
Thereafter, the positive electrode grid 100 is filled with an active material (not shown), aged and dried to form a positive electrode plate, and the lead-acid battery of the present invention can be obtained by using this positive electrode plate.
[0023]
By using the above configuration of the present invention, deformation of the upper frame bone is suppressed even when the positive grid 100 is corroded. The short circuit between the positive electrode and the negative electrode due to the deformed upper frame bone and the decrease in capacity due to the falling of the positive electrode active material can be suppressed by the deformation suppression.
[0024]
In addition, since the falling of the positive electrode active material can be suppressed, a configuration in which the negative electrode plate is stored in the bag-shaped separator in place of the conventional configuration in which the positive electrode is stored in the bag-shaped separator to hold the dropped active material is adopted. be able to. In the configuration in which the negative electrode plate is stored in the bag-shaped separator, there is no problem that occurs when the positive electrode plate is stored in the bag-shaped separator, such that the positive electrode grid deformed by corrosion damages the bottom of the bag-shaped separator.
[0025]
Therefore, in the present invention, if the configuration in which the negative electrode plate is housed in the bag-like separator is employed, it is possible to achieve both the suppression of the falling of the positive electrode active material and the suppression of the damage to the bottom of the bag-like separator.
[0026]
Furthermore, it is preferable to use a Pb-Ca-Sn alloy having a Sn concentration of 1.20% by mass or more as a composition of the lead alloy constituting the positive electrode grid 100 of the present invention. In the present invention, the Ca concentration is not specified, but the Ca concentration is set in the range of 0.04% by mass to 0.10% by mass in consideration of the processability during the expanding process.
[0027]
Further, in the present invention, the upper limit of the Sn concentration is not specified, but as in the case of Ca, an increase in the Sn concentration causes cracks or breaks in the expanded network, so that the upper limit of the Sn concentration is set to 2.0% by mass or less. Is preferred.
[0028]
By setting the Sn concentration in the Pb-Ca-Sn alloy used for the positive electrode grid 100 to 1.20 mass% or more, the corrosion resistance of the Pb-Ca-Sn alloy is improved, and the progress of corrosion of the positive electrode grid can be suppressed. This is advantageous in that the life of the lead storage battery can be extended. However, since the tensile strength of the Pb-Ca-Sn alloy is also improved, the stress on the positive electrode grid increases when the positive electrode grid is corroded. When the bending point of the deformation is set at a certain point as in Patent Document 2 described above, stress concentrates at this bending point. In a Pb-Ca-Sn alloy having a Sn concentration of 1.20% by mass or more, the concentrated stress value increases sharply as compared with a Pb-Ca-Sn alloy having a Sn concentration of less than 1.2% by mass. As a result, the deformation of the positive electrode grid body progresses rapidly, the capacity suddenly decreases, and the battery becomes unusable.
[0029]
In the configuration of the present invention, even when the Pb-Ca-Sn alloy having the Sn concentration as described above is used, the rapid deformation of the upper frame bone can be suppressed by dispersing the stress applied to the upper frame bone.
[0030]
【Example】
Next, examples of the present invention will be described.
[0031]
(1) Example 1
Using a rolled sheet of Pb-0.05 mass% Ca-1.8 mass% Sn alloy, an expanded mesh 201 as shown in FIG. 2 was formed by a rotary expanding method. Next, the expanded mesh 201 was filled with an active material, punched along a cutting line 202 shown by a broken line in FIG. 2 to form a single electrode plate, and then aged and dried to obtain an unformed positive electrode plate.
[0032]
In this example, the values of θ and R of the positive electrode grid of the embodiment of the present invention described above were changed in various combinations to prepare the positive electrode grid of the present invention and the positive electrode grid of the comparative example. . Using these positive plates, a lead-acid storage battery of type 80D26 (JIS D5301) shown in Table 1 was prepared. In this example, the negative electrode plate was housed in a bag-shaped separator made of a microporous polyethylene sheet, and was combined with the positive electrode plate to form an electrode plate group.
[0033]
[Table 1]

[0034]
These batteries were continuously charged at a constant voltage of 14.8 V for 4 weeks in a 40 ° C. atmosphere, and after the charging was completed, the batteries were disassembled and, as shown in FIG. (D) was measured. Then, the ratio of the deformation amount (d) of each battery to the deformation amount of the battery 4 was determined, and the result is shown in Table 1 as a deformation amount ratio d '.
[0035]
Next, FIG. 4 shows the relationship between R and θ and the deformation ratio (d ′) on the vertical axis. From the results shown in FIG. 4, it can be seen that the deformation ratio can be extremely low within the range where θ is in the range of 10 to 40 ° and in the range of the following equation (1).
[0036]
R ≧ 10 ^(2- θ ^{/ 45)} Equation (1)
(However, the unit of R is mm and 10 ° ≦ θ ≦ 40 °)
(2) Example 2
Next, regarding the

batteries

9 and 22 shown in Table 1 of Example 1, batteries in which the Sn concentration in the lead alloy sheet and the polarity of the electrode plate housed in the bag-shaped separator were changed were prepared. Table 2 shows these batteries.
[0037]
[Table 2]

[0038]
For the batteries shown in Table 2, a life cycle test in which charging and discharging were repeated was performed. The test conditions were a 14.8 V constant voltage charge in a 40 ° C. atmosphere for one week, and a constant current discharge at 300 A for 5 seconds in a 25 ° C. atmosphere. These charging and discharging were repeatedly performed, and the point in time when the voltage at the 5th second of discharging decreased to 7.2 V was defined as the number of life cycles. FIG. 5 shows the results of these life tests.
[0039]
From the results shown in FIG. 5, in the region where the Sn concentration in the Pb-Ca-Sn alloy used for the positive electrode lattice is 1.20% by mass or more, the life of the battery of the comparative example is rapidly reduced. On the other hand, the battery of the present invention example shows good life characteristics even when Sn is 1.20% by mass or more.
[0040]
Among them, the battery of the present invention in which the negative electrode plate was housed in the bag-like separator exhibited extremely excellent life characteristics.
[0041]
In the battery of the comparative example in which the Sn concentration was 1.20% by mass or more, the deformation of the upper frame bone of the positive electrode grid was concentrated at one point, and the upper frame bone was bent at that point. On the other hand, in the example of the present invention, even with such Sn concentration, the deformation of the upper frame bone was not concentrated at one place, and the deformation was dispersed. Further, as the Sn concentration was reduced to less than 1.20% by mass, the state where the upper frame bone was intensively bent at one location changed to a state where the entire upper frame bone was deformed. Further, as the Sn concentration decreased, the number of life cycles itself decreased. Therefore, according to the present invention, extremely good life characteristics can be obtained even in a region where the Sn concentration is 1.20% by mass or more.
[0042]
In particular, in the present invention, since the amount of the falling-off active material can be suppressed by suppressing the deformation of the positive electrode grid, it is not necessary to store the positive electrode plate in the bag-like separator as in the conventional case. Therefore, it is possible to avoid a problem when the positive electrode plate is stored in the bag-shaped separator, that is, a problem of a short circuit between the positive electrode and the negative electrode due to breakage of the bottom of the bag-shaped separator.
[0043]
【The invention's effect】
As described above, according to the configuration of the present invention, it is possible to provide a long-life lead-acid battery by solving the problem of battery life reduction due to lattice deformation and active material falling off at the time of corrosion. Useful.
[Brief description of the drawings]
1 is a view showing an electrode grid according to the present invention; FIG. 2 is a view showing an expanded mesh; FIG. 3 is a view showing a measurement position of a deformation amount of an upper frame bone; FIG. 4 is a deformation amount ratio d for each of R and θ. FIG. 5 shows a life test result. FIG. 6 shows a conventional expanded lattice body.
REFERENCE SIGNS LIST 100 Positive grid 101 Upper frame bone 102 Current collecting ear part 103 Expanded mesh 104 Part (of upper frame bone) 105 Inclined part 106 Parallel part 107 Connecting part 108 Extended line 109 Extended line 201 Expanded mesh 202 Cutting line 300 Positive lattice 301 Upper boiling Bone 601 Expanded lattice 602 Expanded mesh 603 Lower frame bone 604 Upper frame bone 605 Current collecting ear

Claims

An expanded mesh formed by expanding a lead alloy sheet into a mesh is provided, and a current collector is provided on an upper frame bone provided in contact with the expanded mesh, and the current collector is eccentric from a center line of the expanded mesh. In the grid body of the provided lead storage battery, a portion corresponding to the expanded mesh end in the center line direction from the current collecting ear of the upper frame bone is close to the expanded mesh end from the current collecting unit. According to the present invention, there is provided an inclined portion having a reduced height dimension (h), and a parallel portion having a constant height dimension (h) provided corresponding to the end of the expanded mesh, between the inclined portion and the parallel portion. A positive electrode grid body for a lead-acid battery, characterized in that a connecting portion for connecting the two with a curve is provided.

The positive electrode grid of a lead-acid battery according to claim 1, wherein the connecting portion has an arc shape.

When the angle formed by the extension line of the upper end of the inclined portion and the extension line of the upper end of the parallel portion is θ (°), and the radius of the arc shape is R (mm), the θ is 10 to 40 °. The positive electrode grid of a lead-acid battery according to claim 2, wherein the relationship between the θ and the R is represented by the following equation (1).
R ≧ 10 ^(2- θ ^{/ 45)} Equation (1)

The positive electrode grid of a lead-acid battery according to claim 1, wherein the Sn concentration in the lead alloy sheet is 1.2% by mass or more and 2.0% by mass or less.

A lead-acid battery, comprising: a positive electrode plate in which an active material is used for the positive electrode grid according to claim 1.

The lead storage battery according to claim 5, further comprising an electrode plate group using the bag-shaped separator accommodating the negative electrode plate and the positive electrode plate.