JP4972818B2

JP4972818B2 - Method for manufacturing grid for lead-acid battery

Info

Publication number: JP4972818B2
Application number: JP2000330753A
Authority: JP
Inventors: 仁渡辺
Original assignee: GS Yuasa International Ltd
Current assignee: GS Yuasa International Ltd
Priority date: 2000-10-30
Filing date: 2000-10-30
Publication date: 2012-07-11
Anticipated expiration: 2020-10-30
Also published as: JP2002134117A

Description

【０００１】
【発明の属する技術分野】
本発明は鉛蓄電池用格子体、特に圧延シートを材料とする格子体の製造方法に関する。
【０００２】
【従来の技術】
鉛蓄電池用の格子体（集電体）としては、従来Ｐｂ−Ｓｂ系合金が用いられてきたが、この合金を用いた電池は過充電時の電解液減少、格子から溶出したＳｂによる自己放電の問題があるため、近年はＰｂ−Ｃａ−Ｓｎ系合金を格子に用いた電池が広く使用されるようになっている。Ｐｂ−Ｃａ−Ｓｎ系合金はＰｂ−Ｓｂ合金に比べ電解液の減少を抑制できるが、過放電放置後の充電受入れ性や深い放電を行うサイクル寿命特性に問題があることが知られている。これらの原因として正極格子と活物質との界面に不働態層が生成する、格子／活物質間の密着性がＰｂ−Ｓｂ系合金を用いた場合よりも弱いことなどが挙げられている。これらの問題を解決するために、正極格子表面にＳｎやＳｂを多く含む層を設ける技術が提案されている（特許第２０９８６６１号など）。
【０００３】
具体的には、Ｐｂ−Ｃａ−Ｓｎ合金厚板にＰｂ−Ｓｎ−Ｓｂ合金（Ｓｎ：１．０〜５．０質量％，Ｓｂ：２．０〜５．０質量％）の薄板を重ね、これらを冷間圧延して一体化した鉛合金シート（クラッドシート）を加工することによって正極用格子体を得るというものである。この方法は合金元素量の調整が容易であり、均一な層の作製が容易であること、溶射、メッキなどのバッチ処理を必要としないために生産性が高いことなどの利点があり、特に鉛合金シートを展開加工して作製するエキスパンド格子に対しては有効な方法である。しかし、Ｓｂを含まない電池に比べるとやはり電解液の減少が多く、電解液の減少が電池容量に大きく影響する負極吸収式密閉鉛蓄電池（以後、密閉式鉛蓄電池と表記する）には採用しがたい。また、定電圧で充電される場合はＳｂの存在によって充電電流が増大し、熱逸走の危険性も増大する。
【０００４】
一方、Ｓｂを含まない合金として密閉式鉛蓄電池のＰｂ−Ｃａ−Ｓｎ合金製の格子表面にＰｂ−Ｓｎ合金（Ｓｎ：３〜２０質量％）層を設けることが（例：特開平５−７４４６４号）提案されているが、サイクル寿命性能はＰｂ−Ｓｂ−Ｓｎ合金層を設けた場合に比べて劣っていた。
【０００５】
【発明が解決しようとする課題】
そこで、Ｓｂを含む合金と同等の不働態層の生成抑制効果があり、かつ電解液の減少がＰｂ−Ｃａ−Ｓｎ合金と同等なＳｂを含まない合金を検討したところ、Ｐｂ−０．２〜１０質量％Ｃａ合金層を正極格子表面に設けることが有効であり、特に２質量％以上のＣａを含むことが望ましいことがわかった（特願平１１−２９２８１１号）。格子体の表面に前記Ｃａ合金層を設ける方法として、上述の格子体の基材となる厚板とＰｂ−０．２〜１０質量％Ｃａ合金薄板を張り合わせて共に冷間圧延する方法は有効であるが、以下の問題があることがわかった。
【０００６】
前記Ｐｂ−Ｃａ合金薄板において、Ｃａ量が２質量％を越えると延性が低下し、脆くなるため圧延が著しく困難になる。そこで特願平１１−２９２８１１では加工性を向上させるためにＳｎを０．１〜１０質量％添加することが提案されている。しかしながら合金箔のＣａ量が３％を越えるとＳｎを１０％添加しても充分な延性が得られず、圧延途中で割れや穴が発生し、合金層（クラッドシート）の作製が困難であった。また、クラッドシートが作製できてもその後の格子加工、例えばエキスパンド加工においてＰｂ−Ｃａ合金層が剥離してしまうという問題があった。
【０００７】
本発明は密閉鉛蓄電池にも適用可能なＳｂを含まない鉛合金からなる格子体（基材）表面に高濃度（特に２〜１０質量％）のＣａを含み、Ｓｂを含まない合金層を設ける方法として以下の方法を採用する際に問題となる合金層の加工性を改善するものである。すなわち、冷間圧延によって基材厚板と前記組成の高Ｃａ合金薄板を一体化する際に、合金薄板のＣａ量が多く（特に２質量％以上に）なると延性が低下して合金層の形成および格子加工が困難になることを解決するものである。
【０００８】
【課題を解決するための手段】
請求項１記載の発明は、Ｓｂ（アンチモン）を含まない鉛合金板Ａの片面もしくは両面の全面または一部に、Ｃａ（カルシウム）とＳｎ（錫）を含みＳｂを含まない鉛合金板Ｂを重ね合わせ、これを冷間圧延して作製した複合シート（クラッドシート）を加工する鉛蓄電池用格子体の製造方法において、前記鉛合金板Ｂは、Ｃａを２〜１０質量％、Ｓｎを５〜２０質量％含みＳｂを含まない組成であって、組成がＣａを０．０２〜０．１質量％、Ｓｎを１．０〜２．４質量％含み、Ｓｂを含まない鉛合金板Ａと重ね合わせる前に加熱処理を施して再結晶化させることを特徴とする鉛蓄電池用格子体の製造方法。
【０００９】
本発明によれば、冷間圧延してクラッドシートを作製する際に、前記組成の鉛合金板Ｂを熱処理によって再結晶させ、延性を大幅に高めてから鉛合金板Ａと重ね合わせることにより、その後の冷間圧延で均質なクラッドシートの作製が容易になる。これを加工して鉛蓄電池用格子体を作製すると、高Ｃａ合金層の割れや剥離が起こらなくなり、格子／活物質界面の腐食層を改質する効果が安定して得られる。
【００１１】
また、本願発明の鉛蓄電池用格子体の製造方法において、鉛合金板Ａの厚さをｔ_A 、鉛合金板Ｂの厚さをｔ_Bとしたとき、ｔ_A ／２００＜ｔ_B ＜ｔ_A ／１０の関係にあれば、さらに効果的である。
【００１２】
このような方法によって作製したクラッドシート（格子体）を加工して正極格子に用いた鉛蓄電池は優れた減液特性、サイクル性能を有する。
【００１３】
【発明の実施の形態】
鉛蓄電池の正極用格子体としては極板作製、電池組立に支障のない機械的強度、および電池使用中の酸化腐食による伸びに対する機械的強度と耐食性とが必要である。通常、Ｓｂを含まない格子で圧延シートを材料とする格子はＰｂ−０．０２〜０．１０質量％Ｃａ−０．５〜２．０質量％Ｓｎ程度の組成の合金を使用する。これよりＣａ量、Ｓｎ量が少ないと機械的強度に劣り、Ｃａ量が多いと腐食されやすくなる。また、Ｓｎ量が多すぎると過時効と呼ばれる現象を起こし、時間と共に機械的強度が低下するためである。
【００１４】
通常、上記組成の鉛合金の圧延は冷間で行う。これは、熱間圧延を行うと充分な機械的強度が得られず、これを加工して鉛蓄電池の正極格子に用いた場合、酸化腐食によって変形しやすくなるためである。
【００１５】
圧延用の上記鉛合金（鋳造板）が引張試験によって示す伸びは１０数％である。クラッドシートの基材としてこれらの組成の鉛合金厚板を用いる場合、高Ｃａ合金薄板がこの鉛合金厚板と同程度以上の延性（伸び）を有していなければ圧延の時にひび割れを起こし、均一なクラッドシートの作製が困難になることが予想された。そこで、２〜１０質量％のＣａを含む高Ｃａ合金薄板の加工性を改善するために次の試験を行った。
【００１６】
上記組成の高Ｃａ合金に３質量％および７質量％のＳｎを添加し、厚さ５ｍｍの鋳造板を作製した後、これを８０±３℃に保った圧延ロールで圧延して厚さ０．５ｍｍの薄板を作製した。この高Ｃａ合金薄板から作製直後および８０℃、１８ｈの熱処理を行った後にＪＩＳＺ２２０１１３Ｂ号引張試験片を取り、引張速度を１０ｍｍ／ｍｉｎとして引張試験を行った。Ｃａ量、熱処理の有無による伸びの変化を図２に示す。この結果から、２〜１０質量％のＣａを含む高Ｃａ合金に少なくとも７質量％のＳｎを添加し、薄板作製後に熱処理を行うと伸びが急増することがわかった。
【００１７】
熱処理によって伸びがほとんど変わらなかった組成（Ｐｂ−３質量％Ｃａ−３質量％Ｓｎ）の薄板と急増した組成（Ｐｂ−３質量％Ｃａ−７質量％Ｓｎ）の薄板の金属組織を観察すると、伸びがほとんど変わらなかったものは圧延組織に沿って再結晶組織が並んでいた（図３）が、伸びが急増した薄板では、圧延組織が完全に再結晶組織に変化（図４）していた。
【００１８】
この組織変化が伸びの急増に関係していることが予想されたため、図３に示した伸びがほとんど変わらなかった組成の薄板に更に高温の熱処理（１５０℃，６ｈ）を施し、金属組織の観察と引張試験を行った。この熱処理後の金属組織を観察すると図４のように全て再結晶組織となっていたが引張試験による伸びはわずかに増大しただけであった。従って、伸びを増大するために必要な条件は一定量以上のＳｎを添加し、これを再結晶化させることであることがわかった。
【００１９】
続いて、高Ｃａ合金の伸びを増大させるのに必要なＳｎの添加量を調べるため、Ｐｂ−７質量％Ｃａ合金に３〜３０質量％のＳｎを添加していった時の伸びについて、前述と同様の引張試験によって調査した。完全に再結晶させるため、熱処理は１５０℃で６ｈ行った。この結果を図５に示す。すなわち、熱処理による再結晶によって伸びが増大し、基材となる鉛合金板Ａと同等以上の伸びを示すようになるには、Ｓｎが５質量％以上添加されていることが必要であることがわかった。
【００２０】
以上に述べたように、本発明の鉛合金板Ｂの組成（Ｐｂ−２〜１０質量％Ｃａ−５〜２０質量％Ｓｎ）の鉛合金は熱処理により伸びは増大するが、機械的強度は大きく低下し、また鉛合金板Ａに用いる鉛合金に比べて腐食されやすいという性質を持っている。従って、格子／活物質界面の不働態層生成を抑制する効果を得るために、クラッドシートのシートＢの合金の厚さｔ_B はシートＡの合金の厚さｔ_A の１／２００以上であることが好ましく、シートＢの合金の特性から格子体の強度と耐食性を考慮すると１／１０以下であることが好ましい。
【００２１】
【実施例】
以下に本発明の実施例を示す。
（実施例１）
Ｐｂ−０．０６質量％Ｃａ−１．５質量％Ｓｎ−０．００５質量％Ａｌ合金からなる厚さ１０ｍｍの鉛合金板Ａと表１に示す各種合金からなる厚さ０．２ｍｍの鉛合金板Ｂを用意した。ここで、合金中のＡｌは合金調合中のＣａの酸化損失を抑える目的で添加しており、通常０．００１〜０．１質量％添加している。
【００２２】
【表１】

【００２３】
表１に示す電池Ｎｏ．１−１用のシートは、鉛合金板Ｂを８０℃で１８ｈ熱処理した後、図１に示すように鉛合金板Ｂ（２）を鉛合金板Ａ（１）と重ね合わせ、冷間圧延により１．０ｍｍのクラッドシート（５）とした。図１において３は金属製ブラシ、４は圧延機、６は鉛合金板Ｂの断面組織（熱処理後）である。Ｎｏ．１−２，１−３のシートは熱処理を行わずに鉛合金板Ｂを鉛合金板Ａに重ね合わせ、Ｎｏ．１−４については鉛合金板Ａのみを冷間圧延し、厚さ１．０ｍｍのシートを作製した。なお、冷間圧延によるシートの接合性を高めるため、各シートの貼合わせ面の酸化層を金属製ブラシ３で除去してから重ね合わせた。
【００２４】
以上のように作製したクラッドシートを展開加工してエキスパンド格子を作製した。展開加工後のエキスパンド格子を観察すると、Ｎｏ．１−２のシートから作製した格子では図６に示すようなシートＢからなる高Ｃａ合金層の剥離７が見られた。Ｎｏ．１−１、１−３のシートから作製した格子ではこのような現象は見られなかった。
【００２５】
これらのエキスパンド格子に正極活物質を充填し、通常の熟成・乾燥を行って正極未化板を作製した。
【００２６】
一方、負極板はＰｂ−０．０７％Ｃａ−０．５％Ｓｎ−０．００２％Ａｌ合金からなる厚さ１．０ｍｍの圧延シートを展開加工して作製した格子体に負極活物質を充填し、通常の熟成・乾燥を行うことによって作製した。これらの極板を微細ガラス繊維セパレータを介して組み合わせ、２Ｖ３０Ａｈ／１０ＨＲの密閉式鉛蓄電池を作製した。各電池の記号は鉛合金板Ｂの記号に同じ（表１）とした。これらの電池を用いてサイクル試験（放電：１０Ａ×１ｈ、充電：３Ａ×５ｈ、４０℃）を行った。５０サイクル毎に容量試験（放電：１０Ａ、終止電圧１．７５Ｖ）と電池質量の測定を行い、容量が初期の７０％を下回った場合に寿命と判定した。
【００２７】
サイクル試験中の容量試験の結果を図７に、電池質量の推移をもとに算出した減液量の推移を図８に示す。
【００２８】
これらの結果から、本発明のクラッドシートを正極格子体に用いた電池（Ｎｏ．１−１）のサイクル寿命はクラッドシートを用いていない従来の電池（Ｎｏ．１−４）の約３倍であり、Ｓｂを含むクラッドシートを正極格子体に用いた電池（Ｎｏ．１−３）と同等以上の性能を示した。Ｎｏ．１−２の電池のサイクル寿命が同じ組成のクラッドシートを用いた電池Ｎｏ．１−１に比べて短かったのは、図６に示したように格子作製の際にシートＢからなる高Ｃａ合金層が剥離してしまったため、格子／活物質界面を改質する効果が減少してしまったものと推察する。図８に示すように、減液量の推移はＳｂを含むＮｏ．１−３の電池が従来電池の約１．５倍と多かったが、本発明のクラッドシートを用いた電池は格子にＳｂを含まない従来電池と同等であった。
【００２９】
（実施例２）
クラッドシートにおける高Ｃａ合金層のＳｎ量の影響について調べるために、実施例１と同様にＰｂ−０．０６質量％Ｃａ−１．５質量％Ｓｎ−０．００５質量％Ａｌ合金からなる厚さ１０ｍｍの鉛合金板ＡとＰｂ−５質量％Ｃａ−３〜３０質量％Ｓｎ−０．００５質量％Ａｌ合金からなる厚さ０．２ｍｍの鉛合金板Ｂを用意した。各種鉛合金板Ｂには１５０℃、６ｈの熱処理を施し、完全に再結晶させてから鉛合金板Ａと合わせて冷間圧延し、実施例１と同様にクラッドシートを作製した。これを展開加工して正極格子体を作製し、その他は実施例１と同一とした密閉式鉛蓄電池（２Ｖ３０Ａｈ／１０ＨＲ）を作製した。これらの電池を用いて実施例１と同じサイクル試験を行った。サイクル試験中の放電終期電圧が１．７Ｖを下回った時点で寿命と判断した。高Ｃａ合金薄板のＳｎ量と寿命サイクル数の関係を図９に示す。
【００３０】
この結果、適当なＳｎ量は５〜２０質量％であり、これよりＳｎ量が多くなるとサイクル寿命は短くなった。寿命後の電池を解体したところ、寿命原因は正極活物質の軟化であったが、高Ｃａ合金層（鉛合金板Ｂ）のＳｎ量が多いほど軟化の程度は大きかった。すなわち、クラッド材作製時に再結晶によって延性が向上させるには５質量％以上のＳｎが必要であるが、過剰量（２０質量％以上）のＳｎは正極活物質の軟化を促進し、また材料コストアップにつながるため、高Ｃａ合金層（シートＢ）のＳｎ量は７〜２０質量％程度が好ましいことがわかった。
【００３１】
【発明の効果】
本発明の製造方法によれば、生産性および減液特性とサイクル寿命性能に優れ、密閉式鉛蓄電池にも使用可能な鉛蓄電池用格子体を得ることができ、これを用いた密閉式鉛蓄電池は、減液特性とサイクル寿命性能に優れたものとなる。
【図面の簡単な説明】
【図１】クラッドシート作製工程の一例を示した図
【図２】高Ｃａ合金薄板のＣａ量、熱処理の有無による伸びの変化を示した図
【図３】熱処理後のＰｂ−３質量％Ｃａ−３質量％Ｓｎ合金薄板の金属組織模式図
【図４】熱処理後のＰｂ−３質量％Ｃａ−７質量％Ｓｎ合金薄板の金属組織模式図
【図５】高Ｃａ合金薄板のＳｎ量による伸びの変化を示した図
【図６】比較用クラッドシートを展開加工して作製したエキスパンド格子の部分拡大図
【図７】サイクル寿命試験中の各電池の容量推移を示した図
【図８】サイクル試験における各電池の減液特性を示した図
【図９】サイクル寿命試験中の各電池の容量推移を示した図
【符号の説明】
１鉛合金板Ａ
２鉛合金板Ｂ
３金属製ブラシ
４圧延機
５クラッドシート
６鉛合金板Ｂの断面組織（熱処理後）
７剥離した高Ｃａ合金層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grid for lead-acid batteries, and more particularly to a method for manufacturing a grid using a rolled sheet as a material.
[0002]
[Prior art]
Conventionally, Pb-Sb alloys have been used as grids (current collectors) for lead-acid batteries, but batteries using these alloys have reduced electrolyte during overcharge and self-discharge due to Sb eluted from the grid. In recent years, batteries using Pb—Ca—Sn alloys as lattices have been widely used. The Pb—Ca—Sn alloy can suppress the decrease of the electrolytic solution as compared with the Pb—Sb alloy, but it is known that there is a problem in charge acceptability after being left overdischarged and cycle life characteristics for performing deep discharge. As these causes, a passive layer is formed at the interface between the positive electrode lattice and the active material, and the adhesion between the lattice / active material is weaker than when a Pb—Sb alloy is used. In order to solve these problems, a technique for providing a layer containing a large amount of Sn or Sb on the surface of the positive electrode lattice has been proposed (Japanese Patent No. 2098661).
[0003]
Specifically, a thin plate of Pb—Sn—Sb alloy (Sn: 1.0 to 5.0 mass%, Sb: 2.0 to 5.0 mass%) is stacked on a Pb—Ca—Sn alloy thick plate, The lead alloy sheet (clad sheet) integrated by cold rolling is processed to obtain a positive electrode grid. This method has advantages such as easy adjustment of the amount of alloying elements, easy production of a uniform layer, and high productivity because it does not require batch processing such as thermal spraying and plating, especially lead. This is an effective method for an expanded lattice produced by developing an alloy sheet. However, compared to batteries that do not contain Sb, the decrease in the electrolyte is still large, and this is adopted for the negative electrode absorption sealed lead-acid battery (hereinafter referred to as the sealed lead-acid battery) where the decrease in the electrolyte greatly affects the battery capacity. It ’s hard. Further, when charged at a constant voltage, the charge current increases due to the presence of Sb, and the risk of thermal escape increases.
[0004]
On the other hand, a Pb—Sn alloy (Sn: 3 to 20 mass%) layer may be provided on the lattice surface made of a Pb—Ca—Sn alloy of a sealed lead-acid battery as an alloy not containing Sb (for example, Japanese Patent Laid-Open No. 5-74464). The cycle life performance was inferior to that in the case where the Pb—Sb—Sn alloy layer was provided.
[0005]
[Problems to be solved by the invention]
Then, when the alloy which does not contain Sb equivalent to the Pb-Ca-Sn alloy in which the reduction | decrease of electrolyte solution has the effect of suppressing the production | generation of a passive layer equivalent to the alloy containing Sb, and Pb-Ca-Sn was examined, Pb-0.2- It has been found that it is effective to provide a 10% by mass Ca alloy layer on the surface of the positive electrode lattice, and in particular, it is desirable to contain 2% by mass or more of Ca (Japanese Patent Application No. 11-29281). As a method for providing the Ca alloy layer on the surface of the lattice body, a method in which the thick plate as the base material of the lattice body and a Pb-0.2 to 10 mass% Ca alloy thin plate are bonded together and cold-rolled together is effective. However, the following problems were found.
[0006]
In the Pb—Ca alloy thin plate, if the Ca content exceeds 2 mass%, the ductility is lowered and the brittleness becomes brittle, so that rolling becomes extremely difficult. Therefore, Japanese Patent Application No. 11-29281 proposes to add 0.1 to 10% by mass of Sn in order to improve workability. However, if the Ca content of the alloy foil exceeds 3%, sufficient ductility cannot be obtained even if Sn is added to 10%, and cracks and holes are generated during rolling, making it difficult to produce an alloy layer (clad sheet). It was. Further, even if the clad sheet can be produced, there is a problem that the Pb—Ca alloy layer is peeled off in subsequent lattice processing, for example, expansion processing.
[0007]
The present invention is applicable to sealed lead-acid batteries, and is made of a lead alloy containing no Sb, and a base material (base material) is provided with an alloy layer containing Ca at a high concentration (particularly 2 to 10% by mass) and not containing Sb. As a method, the workability of the alloy layer, which becomes a problem when the following method is adopted, is improved. That is, when the base plate and the high-Ca alloy thin plate having the above composition are integrated by cold rolling, if the amount of Ca in the alloy thin plate is large (particularly 2% by mass or more), the ductility decreases and the formation of the alloy layer It also solves the difficulty of lattice processing.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, a lead alloy plate B that contains Ca (calcium) and Sn (tin) and does not contain Sb is formed on one surface or both surfaces of a lead alloy plate A that does not contain Sb (antimony). In the method of manufacturing a lead-acid battery grid for processing a composite sheet (cladding sheet) produced by superimposing and cold rolling this, the lead alloy plate B contains 2 to 10% by mass of Ca and 5 to Sn. It is a composition that contains 20% by mass and does not contain Sb, and the composition overlaps with the lead alloy plate A that contains 0.02 to 0.1% by mass of Ca, 1.0 to 2.4% by mass of Sn, and does not contain Sb. method for manufacturing a grid for a lead-acid battery, characterized in that recrystallization by facilities to heat treatment prior to combining.
[0009]
According to the present invention, when producing a clad sheet by cold rolling, the lead alloy plate B having the above composition is recrystallized by heat treatment, and the ductility is greatly increased and then superposed on the lead alloy plate A, Subsequent cold rolling facilitates the production of a homogeneous clad sheet. When this is processed to produce a lead-acid battery grid, cracking and peeling of the high Ca alloy layer do not occur, and the effect of modifying the corrosion layer at the grid / active material interface can be stably obtained.
[0011]
Further, in the method for producing a lead-acid battery grid of the present invention, when the thickness of the lead alloy plate A is t _A and the thickness of the lead alloy plate B is t _B , t _A / 200 <t _B <t _A A / 10 relationship is even more effective.
[0012]
Lead-acid batteries superior reduction solution characteristics used for the positive electrode grid by processing a clad sheet produced (grid) by a method as this, with a cycle performance.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
As a positive electrode grid for a lead-acid battery, electrode plate production, mechanical strength that does not hinder battery assembly, and mechanical strength and corrosion resistance against elongation due to oxidative corrosion during battery use are required. Usually, an alloy having a composition of about Pb-0.02 to 0.10 mass% Ca-0.5 to 2.0 mass% Sn is used as a lattice made of a rolled sheet with a lattice not containing Sb. If the amount of Ca and Sn is less than this, the mechanical strength is poor, and if the amount of Ca is large, corrosion tends to occur. Moreover, if the amount of Sn is too large, a phenomenon called overaging occurs, and the mechanical strength decreases with time.
[0014]
Usually, the lead alloy having the above composition is cold-rolled. This is because, when hot rolling is performed, sufficient mechanical strength cannot be obtained, and when this is processed and used for a positive electrode grid of a lead storage battery, it tends to be deformed by oxidative corrosion.
[0015]
The elongation of the lead alloy (casting plate) for rolling shown by a tensile test is 10 and several percent. When using a lead alloy thick plate of these compositions as the base material of the clad sheet, if the high Ca alloy thin plate does not have ductility (elongation) equal to or higher than this lead alloy thick plate, it will crack at the time of rolling, It was expected that it would be difficult to produce a uniform clad sheet. Then, the following test was done in order to improve the workability of the high Ca alloy thin plate containing 2 to 10% by mass of Ca.
[0016]
After adding 3 mass% and 7 mass% Sn to the high Ca alloy having the above composition to produce a cast plate having a thickness of 5 mm, this was rolled with a rolling roll maintained at 80 ± 3 ° C. to obtain a thickness of 0. A 5 mm thin plate was produced. A JIS Z220113B tensile test piece was taken immediately after fabrication from this high Ca alloy thin plate and after heat treatment at 80 ° C. for 18 hours, and a tensile test was conducted at a tensile speed of 10 mm / min. FIG. 2 shows changes in elongation depending on the amount of Ca and the presence or absence of heat treatment. From this result, it was found that when at least 7% by mass of Sn is added to a high Ca alloy containing 2-10% by mass of Ca and heat treatment is performed after the thin plate is produced, the elongation increases rapidly.
[0017]
When observing the metal structure of a thin plate having a composition (Pb-3 mass% Ca-3 mass% Sn) whose elongation was hardly changed by heat treatment and a rapidly increasing composition (Pb-3 mass% Ca-7 mass% Sn), In the case where the elongation was almost unchanged, the recrystallized structure was lined up along the rolling structure (FIG. 3), but in the thin plate where the elongation increased rapidly, the rolled structure was completely changed to the recrystallized structure (FIG. 4). .
[0018]
Since it was predicted that this structural change was related to a rapid increase in elongation, a thin plate having a composition with almost no change in elongation shown in FIG. 3 was further subjected to a high-temperature heat treatment (150 ° C., 6 hours) to observe the metal structure. And a tensile test. When the metal structure after the heat treatment was observed, it was recrystallized as shown in FIG. 4, but the elongation by the tensile test was only slightly increased. Therefore, it has been found that the condition necessary for increasing the elongation is to add a certain amount or more of Sn and recrystallize it.
[0019]
Subsequently, in order to investigate the amount of Sn added to increase the elongation of the high Ca alloy, the elongation when 3-30 mass% Sn was added to the Pb-7 mass% Ca alloy was described above. The same tensile test was conducted. In order to completely recrystallize, heat treatment was performed at 150 ° C. for 6 hours. The result is shown in FIG. That is, it was found that it is necessary to add 5% by mass or more of Sn in order to increase the elongation by recrystallization by heat treatment and to exhibit an elongation equal to or higher than that of the lead alloy plate A as the base material. .
[0020]
As described above, the lead alloy of the composition (Pb-2 to 10% by mass Ca-5 to 20% by mass Sn) of the lead alloy plate B of the present invention increases in elongation by heat treatment, but has high mechanical strength. It has a property that it is reduced and is more easily corroded than the lead alloy used in the lead alloy plate A. Therefore, in order to obtain the effect of suppressing the generation of a passive layer at the lattice / active material interface, the thickness t _B of the sheet B of the clad sheet is 1/200 or more of the thickness t _A of the alloy of the sheet A. In consideration of the strength and corrosion resistance of the lattice from the characteristics of the alloy of the sheet B, it is preferably 1/10 or less.
[0021]
【Example】
Examples of the present invention are shown below.
Example 1
Pb-0.06 mass% Ca-1.5 mass% Sn-0.005 mass% Lead alloy plate A made of Al alloy and 10 mm thick lead alloy plate A and 0.2 mm thick lead alloy made of various alloys shown in Table 1 Plate B was prepared. Here, Al in the alloy is added for the purpose of suppressing the oxidation loss of Ca during alloy preparation, and is usually added in an amount of 0.001 to 0.1% by mass.
[0022]
[Table 1]

[0023]
Battery No. shown in Table 1 1-1, after the lead alloy plate B was heat-treated at 80 ° C. for 18 hours, the lead alloy plate B (2) was superposed on the lead alloy plate A (1) as shown in FIG. A 1.0 mm clad sheet (5) was obtained. In FIG. 1, 3 is a metal brush, 4 is a rolling mill, and 6 is a cross-sectional structure of the lead alloy plate B (after heat treatment). No. In the sheets 1-2 and 1-3, the lead alloy plate B was superposed on the lead alloy plate A without performing heat treatment. For 1-4, only the lead alloy plate A was cold-rolled to produce a sheet having a thickness of 1.0 mm. In addition, in order to improve the bondability of the sheet | seat by cold rolling, it overlap | superposed after removing the oxide layer of the bonding surface of each sheet | seat with the metal brush 3. FIG.
[0024]
The clad sheet produced as described above was developed to produce an expanded lattice. When the expanded lattice after unfolding was observed, no. In the lattice produced from the sheet 1-2, peeling 7 of the high Ca alloy layer made of the sheet B as shown in FIG. 6 was observed. No. Such a phenomenon was not observed in the lattice produced from the sheets 1-1 and 1-3.
[0025]
These expanded lattices were filled with a positive electrode active material, and subjected to normal aging and drying to produce a positive electrode undeveloped plate.
[0026]
On the other hand, the negative electrode plate is filled with a negative electrode active material in a lattice produced by developing a 1.0 mm thick rolled sheet made of Pb-0.07% Ca-0.5% Sn-0.002% Al alloy. It was prepared by normal aging and drying. These electrode plates were combined through a fine glass fiber separator to produce a sealed lead-acid battery of 2V30Ah / 10HR. The symbol of each battery was the same as that of the lead alloy plate B (Table 1). A cycle test (discharge: 10 A × 1 h, charge: 3 A × 5 h, 40 ° C.) was performed using these batteries. A capacity test (discharge: 10 A, final voltage 1.75 V) and battery mass were measured every 50 cycles, and the life was determined when the capacity was below 70% of the initial value.
[0027]
FIG. 7 shows the results of the capacity test during the cycle test, and FIG. 8 shows the transition of the liquid reduction amount calculated based on the transition of the battery mass.
[0028]
From these results, the cycle life of the battery (No. 1-1) using the clad sheet of the present invention for the positive electrode grid is about three times that of the conventional battery (No. 1-4) not using the clad sheet. Yes, it showed the same or better performance as the battery (No. 1-3) using the clad sheet containing Sb as the positive electrode grid. No. Battery No. 1-2 using a clad sheet having the same cycle life of the battery No. 1-2. As compared with 1-1, the effect of modifying the lattice / active material interface was reduced because the high Ca alloy layer made of sheet B was peeled off during the fabrication of the lattice as shown in FIG. I guess it has been done. As shown in FIG. 8, the transition of the liquid reduction amount is No. including Sb. Although the battery of 1-3 was about 1.5 times as large as the conventional battery, the battery using the clad sheet of the present invention was equivalent to the conventional battery containing no Sb in the lattice.
[0029]
(Example 2)
In order to investigate the effect of the Sn content of the high Ca alloy layer in the clad sheet, the thickness of the Pb-0.06 mass% Ca-1.5 mass% Sn-0.005 mass% Al alloy as in Example 1. A 0.2 mm thick lead alloy plate B made of a 10 mm lead alloy plate A and Pb-5 mass% Ca-3 to 30 mass% Sn-0.005 mass% Al alloy was prepared. Various lead alloy plates B were subjected to heat treatment at 150 ° C. for 6 hours and completely recrystallized, and then cold-rolled together with the lead alloy plate A, and clad sheets were produced in the same manner as in Example 1. This was developed to produce a positive electrode grid, and a sealed lead-acid battery (2V30Ah / 10HR) identical to that of Example 1 was produced. The same cycle test as in Example 1 was performed using these batteries. When the end-of-discharge voltage during the cycle test fell below 1.7V, the life was judged. FIG. 9 shows the relationship between the Sn content of the high Ca alloy thin plate and the number of life cycles.
[0030]
As a result, the appropriate amount of Sn was 5 to 20% by mass, and the cycle life was shortened as the amount of Sn increased. When the battery after the life was disassembled, the cause of the life was softening of the positive electrode active material, but the degree of softening was greater as the amount of Sn in the high Ca alloy layer (lead alloy plate B) was larger. That is, 5% by mass or more of Sn is required to improve ductility by recrystallization during clad material preparation, but an excessive amount (20% by mass or more) of Sn promotes softening of the positive electrode active material and increases the material cost. It was found that the Sn content of the high Ca alloy layer (sheet B) is preferably about 7 to 20% by mass because it leads to an increase.
[0031]
【Effect of the invention】
According to the manufacturing method of the present invention, it is possible to obtain a lead-acid battery grid body that is excellent in productivity, liquid reduction characteristics, and cycle life performance, and can be used for a sealed lead-acid battery, and the sealed lead-acid battery using this Has excellent liquid reduction properties and cycle life performance.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a clad sheet manufacturing process. FIG. 2 is a diagram showing changes in elongation of a high Ca alloy thin plate depending on the amount of Ca and the presence or absence of heat treatment. FIG. 3 is Pb-3 mass% Ca after heat treatment. -3 wt% Sn alloy sheet metal structure schematic diagram [Fig. 4] Pb-3 wt% Ca-7 wt% Sn alloy sheet metal plate after heat treatment Fig. 5 Elongation of high Ca alloy sheet due to Sn amount Fig. 6 is a partially enlarged view of an expanded lattice produced by developing a comparative clad sheet. Fig. 7 is a diagram showing the capacity transition of each battery during a cycle life test. Fig. 9 shows the liquid reduction characteristics of each battery in the test. Fig. 9 shows the capacity transition of each battery during the cycle life test.
1 Lead alloy plate A
2 Lead alloy plate B
3 Metal brush 4 Rolling machine 5 Clad sheet 6 Cross sectional structure of lead alloy plate B (after heat treatment)
7 Peeled high Ca alloy layer

Claims

A lead alloy plate B that contains Ca (calcium) and Sn (tin) and does not contain Sb is superposed on one or both sides of the lead alloy plate A that does not contain Sb (antimony), and is cold-rolled. In the method for manufacturing a lead-acid battery grid for processing a composite sheet (clad sheet) produced in the above-described manner, the lead alloy plate B includes 2 to 10% by mass of Ca, 5 to 20% by mass of Sn, and does not include Sb. a composition, the composition is 0.02 to 0.1 wt% of Ca, include Sn from 1.0 to 2.4 wt%, and facilities to heat treatment prior to overlaying with lead alloy sheet a without Sb And recrystallizing the lead-acid battery grid.