JP2004119089A

JP2004119089A - Square shape storage battery for back up

Info

Publication number: JP2004119089A
Application number: JP2002278410A
Authority: JP
Inventors: Nobuyasu Morishita; 森下　展安; Toshifumi Ueda; 植田　利史; Kazuhiro Okawa; 大川　和宏; Yoshitada Nakao; 中尾　善忠; Takahisa Masashiro; 正代　尊久; Keiichi Saito; 斉藤　景一; Hiroshi Wakagi; 若木　寛
Original assignee: Nippon Telegraph and Telephone Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Nippon Telegraph and Telephone Corp; Panasonic Holdings Corp
Priority date: 2002-09-25
Filing date: 2002-09-25
Publication date: 2004-04-15
Anticipated expiration: 2022-09-25
Also published as: JP4056340B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a square storage battery for back up use made of a nickel-hydrogen storage battery which has a large capacity, and in which desired charging efficiency can be obtained even under a high environmental temperature and the occurrence of leakage of liquid can be prevented surely. <P>SOLUTION: The square nickel-hydrogen storage battery 11 houses an electrolode plate group 20 comprising by laminating a positive electrode plate 21 containing a positive electrode material made mainly of nickel hydroxide and a negative electrode plate 22 containing a negative electrode material made mainly of a hydrogen storage alloy are laminated via a separator 23 in the square battery case 24 together with an electrolytic solution. External terminals 27, 28 of the positive electrode and the negative electrode are arranged on one face of the square case 24 and respective external terminals 27, 28 are sealed to duplicate by a plurality of annular packings 42, 45 at the penetrating part of the square battery case, and at least Co and Yb<SB>2</SB>O<SB>3</SB>are contained in the positive electrode material. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明はバックアップ用角形蓄電池に関し、特にニッケル水素蓄電池から成るとともに容量が大きくかつ環境温度が高い状態でも所望の充電効率が得られるバックアップ用角形蓄電池に関するものである。
【０００２】
【従来の技術】
従来、例えば通信基地局におけるバックアップ用蓄電池としては、鉛蓄電池が一般的に用いられていた。しかし、近年になって基地局機能の多機能化が進展し、それに伴って電源容量を数十〜百数十Ａｈに大容量化することが要請されており、その要請に鉛蓄電池で対処しようとすると、容積及び重量が大きくなり過ぎ、一層のコンパクト化に対する要請に反するという問題がある。また、環境問題への配慮から鉛やカドミウムを含まない蓄電池の採用が望まれている。
【０００３】
そこで、民生用の単３の円筒形のニッケル水素電池を用いることが考えられる。即ち、複数個のニッケル水素電池を直列接続して構成した電池モジュールを複数、直列及び並列に接続することで所望の出力電圧と容量を確保することが考えられるが、多数の電池を接続する必要があるため、構成が複雑になってコスト高になるという問題がある。
【０００４】
また、多数のニッケル水素電池の端子同士を接続するため、接続抵抗が大きくなって高出力時に電圧低下を来すとともに、発熱量が大きくなって環境温度を高くし、充電効率を一層低下させるという問題がある。特に、通信基地局におけるバックアップ用蓄電池は、機器に悪影響を与えないために清浄な雰囲気が要請されること及び保安上の理由から、機器とともにほぼ密閉された空間に配設されることから、大量の外気をそのまま導入して冷却することができず、そのため元々環境温度が高くなりがちであるために、致命的な問題である。
【０００５】
さらに、比較的大容量の大型の円筒形のニッケル水素電池を構成して、構成の単純化とコスト低下を図るとともに、接続抵抗の低減を図ることが考えられるが、円筒形ではその中心部の放熱が十分に行われず、高温になるため充電効率が低下するという問題がある。
【０００６】
そこで、水酸化ニッケルを主体とする正極材料を含む正極板と水素吸蔵合金を主体とする負極材料を含む負極板とをセパレータを介して積層してなる極板群を電解液とともに角形電槽内に収容して成る比較的大容量の角形ニッケル水素蓄電池を、このようなバックアップ用蓄電池に適用することが考えられる。
【０００７】
この種の角形ニッケル水素蓄電池において、正極板の正極材料には導電性を向上するために水酸化ニッケルにＣｏＯ添加したものが知られている。なお、導電性の向上に関しては金属Ｃｏを添加した方が一層効果的であるが、放電した状態で放置すると微小短絡が発生して寿命低下を来すために、ＣｏではなくＣｏＯが添加されている。また、電解液としては、ＫＯＨとＮａＯＨとＬｉＯＨの３成分から成り、その組成比が、例えばＫＯＨ：ＮａＯＨ：ＬｉＯＨ＝４：２．５：１のように、抵抗の小さい抵抗値が得られるＫＯＨの量を多くして、ＫＯＨ＞ＮａＯＨ＞ＬｉＯＨとしたものが一般に使用されている（例えば、特許文献１参照。）。
【０００８】
また、電槽上面に配設される正極と負極の接続端子の電槽上壁の貫通部は単一の環状パッキンにてシールされている（例えば、特許文献２参照。）。
【０００９】
【特許文献１】
特開平６−４５００２号
【００１０】
【特許文献２】
特開平１０−１８８９４４号公報（第２、４、５頁、図２）
【００１１】
【発明が解決しようとする課題】
ところが、上記従来の角形ニッケル水素蓄電池の構成では、接続端子が上壁を貫通する部分で、単一の環状パッキンにて１重にのみシールしているので、バックアップ用電源として、上記のように高温の環境温度に長期間晒されると、貫通部から液漏れが発生する恐れがあるという問題がある。
【００１２】
また、バックアップ用蓄電池においては環境温度が高温であるため、高温での充電効率が十分に高いことが求められるが、上記従来の角形ニッケル水素蓄電池では高温での充電効率が急激に低下するという問題があることが判明した。例えば、２５℃の充電効率を１００％として、５５℃で５０〜６０％程度になってしまい、例えば容量が１００Ａｈの蓄電池によって、−１０℃で８０Ａｈ以上、５５℃で９０Ａｈ以上という要求された充電容量を満たすことができないという問題がある。
【００１３】
本発明は、上記従来の問題点に鑑み、容量が大きくかつ環境温度が高い状態でも所望の充電効率が得られ、液漏れの発生を確実に防止できるニッケル水素蓄電池から成るバックアップ用角形蓄電池を提供することを目的としている。
【００１４】
【課題を解決するための手段】
本発明のバックアップ用角形蓄電池は、水酸化ニッケルを主体とする正極材料を含む正極板と水素吸蔵合金を主体とする負極材料を含む負極板とをセパレータを介して積層してなる極板群を電解液とともに角形電槽内に収容して成る角形ニッケル水素蓄電池から成り、角形電槽の一面に正極と負極の外部端子を配設し、各外部端子は角形電槽の貫通部で複数の環状パッキンにて二重にシールし、正極材料に、少なくともＣｏとＹｂ化合物を含むものである。
【００１５】
この構成によれば、外部端子の角形電槽の貫通部が複数の環状パッキンにて二重にシールされているため、高温の環境温度で長期間使用しても確実に液漏れを防止することができる。また、角形で大容量の蓄電池において正極板の各部位とリード部までの距離が長くなっても、正極材料にＣｏを含んでいることで抵抗を小さくできて充電効率を向上でき、かつバックアップ用であるため絶えず満充電状態に維持されることから金属Ｃｏを含んでいても、放電状態で放置されるような状態になることがないので、微小短絡によって寿命が低下するというような弊害を生じることもない。また、正極材料にＹｂ化合物を含んでいることで、高温域の充電効率を飛躍的に向上することができる。なお、Ｙｂ化合物としては、Ｙｂ_２Ｏ_３が好適であるが、Ｙｂ（ＯＨ）_３でも同様の作用が得られる。
【００１６】
Ｃｏの含有量は、水酸化ニッケル１００重量部に対して４〜８重量部で、Ｙｂ化合物の含有量は、水酸化ニッケル１００重量部に対して１〜６重量部であるのが好適である。Ｃｏが４重量部未満では上記抵抗低減効果が十分でなく、８重量部を越えると、その分水酸化ニッケル量が相対的に低下するため一定体積当たりの容量が低下することになる。また、Ｙｂ化合物の含有量が１重量部未満では高温充電効率の向上効果が十分に得られず、６重量部を越えるとその分水酸化ニッケル量が相対的に低下するため一定体積当たりの容量が低下することになる。Ｃｏの含有量が５重量部、Ｙｂ化合物の含有量が４重量部程度が最適である。
【００１７】
さらに、電解液が、ＮａＯＨ、ＫＯＨ、ＬｉＯＨの３成分から成り、その組成をＮａＯＨ≧ＫＯＨ＞ＬｉＯＨとすると、高温での抵抗値の低いＮａＯＨの量が多いことで、高温充電効率の特性を全体的に高温側にシフトでき、高温域での充電効率を向上することができる。
【００１８】
また、角形電槽が合成樹脂製であると、蓄電池の温度及び内圧が急激に上昇するような異常反応が発生した場合に、内圧が高くならないうちに電槽が軟化するため、電槽破裂の恐れなしにガスを放出でき、また外部端子部の絶縁も容易に確保できるため、多量の蓄電池をシステムとして使用するときに高い安全性を確保することができる。
【００１９】
また、以上の構成は容量が３０Ａｈ以上の大きな容量の蓄電池において特に効果的である。
【００２０】
また、上記構成のバックアップ用角形蓄電池を複数直列接続し、かつ各バックアップ用角形ニッケル水素蓄電池間に冷却通路を設けた状態で一体的に結合してバックアップ用角形蓄電池モジュールを構成すると、出力電圧を高くできるとともに各蓄電池を効果的に冷却して温度上昇を抑制でき、雰囲気温度が高くても高い充電効率を確保することができる。
【００２１】
【発明の実施の形態】
以下、本発明のバックアップ用角形蓄電池の一実施形態について、図１〜図７を参照して説明する。
【００２２】
まず、本実施形態のバックアップ用角形蓄電池を適用する、通信基地局における電源バックアップシステムの概略構成を図１を参照して説明する。図１において、商用電源１から整流器２を介して基地局用の各種機器から成る負荷３に対して電力を供給するように構成され、かつ整流器２と負荷３の間に、並列接続された一対の電池パック５ａ、５ｂと放電制御手段６とを直列接続したバックアップ用電源回路４が並列接続されている。電池パック５ａ、５ｂには温度上昇を抑制するための冷却風を送風する冷却ファン７が付設されている。また、整流器２と電池パック５ａ、５ｂの間に充電手段８を接続して電池パック５ａ、５ｂに対して充電を行うように構成されている。
【００２３】
電池パック５ａ、５ｂにおける電圧と電流と温度が検出され、これら電圧情報、電流情報、温度情報が電池監視手段９に入力されて電池の状態が監視されている。電池監視手段９は、電池パック５ａ、５ｂの電気量（ＳＯＣ）を演算し、充電要求、充電停止要求、放電可否通知、電池状態通知、安全制御、及び冷却ファン７の動作制御を行う。電池監視手段９からその監視情報が制御部１０に入力され、制御部１０にて電池パック５ａ、５ｂの状態に応じて整流器２、充電手段８、放電制御手段６を制御するように構成されている。なお、一対の電池パック５ａ、５ｂは、何れかのメンテナンス時に商用電源１が停電した場合でも確実に電力を供給できるように設けられ、またこれら電池パック５ａ、５ｂに対する充電を、適当な時間間隔をおいてかつ両電池パック５ａ、５ｂに対する充電期間が互いに異なるように交互に行うことで常に何れかは満充電に近い状態になっているように構成されている。
【００２４】
電池パック５ａ、５ｂはそれぞれ、図２（ａ）、（ｂ）に示すように、１０個の角形ニッケル水素蓄電池１１を並列配置して一体的に拘束することで電池モジュール１２を構成し、この電池モジュール１２を４個並列配置して構成されている。電池パック５ａ、５ｂの出力電圧は、出力電圧が１．２Ｖの角形ニッケル水素蓄電池１１を１０個直列接続して出力電圧を１２Ｖとした電池モジュール１２を４個直列接続して４８Ｖとされている。
【００２５】
各電池パック５ａ、５ｂは、上部に基地局用の機器配置空間１４を設けた筐体１３の下部に形成されたバックアップ用電源配置空間１５に配設され、その下部と上部に冷却風路１６ａ、１６ｂが設けられている。すなわち、電池パック５ａ、５ｂを構成する各電池モジュール１２が、下部に冷却風路１６ａをあけて設けられた支持桟１７上に設置されている。下部の冷却風路１６ａの一端には送風ファン７が配設され、フィルタ１８を介して冷却風を導入し、上部の冷却風路１６ｂの一端に配設された排気グリル１９から排出するように構成されている。
【００２６】
各電池モジュール１２は、図３に示すように、１０個のニッケル水素角形蓄電池１１（１１ａ〜１１ｊ）を、その電槽の幅の広い長側面同士を互いに対向させて重ねるように配置し、両端の単電池１１ａ、１１ｊの電槽の外側にエンドプレート３２を当接させ、両エンドプレート３２、３２間を拘束バンド３３にて結束することにより一体的に連結して構成されている。
【００２７】
各ニッケル水素角形蓄電池１１は、図４、図５に示すように、正極板２１と負極板２２をセパレータ２３を介して積層してなる極板群２０を電解液と共に電槽２４内に収容し、各電槽２４の開口部を安全弁２６を設けた蓋２５で閉じ、極板群２０を構成する各正極板２１の一側部上端から上方にリード２９を引き出してその上部に正極端子２７を接続し、また同様に各負極板２２の他側部上端から上方にリード２９を引き出してその上部に負極端子２８を接続し、これら外部端子としての正極端子２７及び負極端子２８を蓋２５に取付けて構成されている。極板群２０の正極板２１及び負極板２２の大きさと積層枚数は、例えば１００Ａｈの容量が得られるように設計され、その場合各極板の大きさは下端から上端までの距離が例えば１００〜１５０ｍｍ程度となる。
【００２８】
そして、各電池モジュール１２において、隣り合うニッケル水素角形蓄電池１１、１１間の正極端子２７と負極端子２８とが接続板３１にて接続されて各ニッケル水素角形蓄電池１１が直列接続されている。また、各電槽２４、２４間が接合されるとき、電槽２４の長側面に上下方向に突設されたリブ３０が隣接間で突き合わされ、各リブ３０、３０間の長側面間の空間にて電槽２４の上下方向に貫通する冷却通路３０ａが形成され、冷却通路３０ａに送風して各ニッケル水素角形蓄電池１１ａ〜１１ｊを冷却するように構成されている。
【００２９】
正極端子２７や負極端子２８は、図５に示すように、蓋２５に形成された端子貫通穴３４を貫通するポール部３５の上部に接続用のねじ部３６が設けられ、下部に方形のフランジ部３７が形成され、このフランジ部３７の下面に適当間隔おきに複数の集電鍔３８を垂設した構成とされている。蓋２６の上面の端子貫通穴３４の周囲には座金３９が配置され、この座金３９上に配置した環状押圧ばね４０の内周縁をポール部３５の外周面に弾性係止させることで、これら端子２７、２８が蓋２５に固定されている。
【００３０】
フランジ部３７の上面には環状の封止溝４１が形成されてＯリングなどの環状パッキン４２が収容配置されるとともにピッチなどのシール剤４３が充填配置され、蓋２５の下面とこの封止溝４１の間で環状パッキン４２を圧縮させるとともに、その周辺に充填されたシール剤４３にて１段目のシールが行われている。また、端子貫通穴３４の上部にはテーパシール面４４が形成されてＯリングなどの環状パッキン４５が配置され、テーパシール面４４と座金３９の間で環状パッキン４５を圧縮させることで２段目のシールが行われ、環状パッキン４２、４５により２重にシールが施されている。
【００３１】
フランジ部３７から垂設された集電鍔３８にはリード２９をレーザビーム溶接や電子ビーム溶接にて溶接接合して電気的に接続されている。また、フランジ部３７の両側端面３７ａが蓋２５に設けられた位置決め突部４６に係合され、ねじ部３６に対する接続板３１の締結時に回り止め機能を奏するように構成されている。
【００３２】
ニッケル水素角形蓄電池１１の極板群２０を構成する正極板２１はＮｉの発泡メタルに水酸化ニッケル（本発明ではＣоなどを固溶、コートしたものなどについてもＮｉ（ＯＨ）_２と記す）を主材料とする正極材料を塗着保持させて構成され、負極板２２はＮｉのパンチングメタルに水素吸蔵合金を主材料とする負極材料を塗着保持させて構成され、セパレータ２３はポリアミド系やポリオレフィン系の不織布にて構成されている。
【００３３】
そして、本実施形態では、水酸化ニッケルを主体とする正極材料に少なくともＣｏと、Ｙｂ_２Ｏ_３やＹｂ（ＯＨ）_３などのＹｂ化合物を含んでいる。具体的には、Ｃｏは、Ｎｉ（ＯＨ）_２１００重量部に対して４〜８重量部含有し、Ｙｂ化合物は１〜６重量部含んでいる。具体例を示すと、Ｎｉ（ＯＨ）_２：１００重量部、Ｃｏ：５重量部、Ｃｏ（ＯＨ）_２：５重量部、Ｙｂ_２Ｏ_３：４重量部、ＺｎＯ：２．５重量部にて正極材料が構成されている。
【００３４】
また、電解液は、ＮａＯＨ、ＫＯＨ、ＬｉＯＨの３成分の混合液にて構成し、かつその組成をＮａＯＨ≧ＫＯＨ＞ＬｉＯＨとしている。具体例を示すと、電解液の組成比を、ＮａＯＨ：ＫＯＨ：ＬｉＯＨ＝４：２．５：１としている。なお、電解液の濃度は、７．５ｍｏｌ／Ｌとしている。
【００３５】
以上の構成の角形ニッケル水素蓄電池１１においては、角形の電槽２４の上面に正極端子２７と負極端子２８を配設し、これらの端子２７、２８は電槽２４の蓋２５の貫通部で複数の環状パッキン４２、４５にて二重にシールしているため、５５℃程度の高温の環境温度となることがあるバックアップ用電源配置空間１５内に配置して長期間使用しても液漏れを確実に防止することができ、漏液による短絡等の発生を防止して高い安全性を確保できる。
【００３６】
また、正極板２１の正極材料にＣｏを含んでいるため、正極板２１の下端から上端までの距離が１００〜１５０ｍｍ程度と大きくても、導電性の高い金属Ｃｏの存在によって正極板２１の抵抗を小さくできて充電効率を向上できる。また、このように金属Ｃｏを含んでいても、バックアップ用であるため絶えず満充電状態に維持され、放電状態で放置されるような状態になることがないので、微小短絡によって寿命が低下するというような弊害を生じることもない。
【００３７】
また、正極板２１の正極材料にＹｂ化合物を含んでいることで、高温域の充電効率を飛躍的に向上することができる。
【００３８】
さらに、電解液が、ＮａＯＨ、ＫＯＨ、ＬｉＯＨの３成分から成り、その組成をＮａＯＨ：ＫＯＨ：ＬｉＯＨ＝４：２．５：１とし、高温での抵抗値の低いＮａＯＨの量を多くしているので、高温充電効率の特性を全体的に高温側にシフトでき、高温域での充電効率を向上することができる。なお、ＮａＯＨの量を多くすると、出力特性と背反するが、バックアップ用電源の用途では問題とならない。
【００３９】
かくして、上記１００Ａｈの容量の角形ニッケル水素蓄電池１１を用いることで、図６に示すように、−１０℃で８０Ａｈ以上、５５℃で９０Ａｈ以上の容量を確保することができた。なお、図６中に、比較のため、Ｃｏに代えてＣｏＯを含有し、Ｙｂ_２Ｏ_３を含有していない従来例の場合を破線で示している。
【００４０】
また、上記角形ニッケル水素蓄電池１１を複数並列配置して一体的に結合した各電池モジュール１２において、角形ニッケル水素蓄電池１１、１１間に冷却通路３０ａを形成しているので、各蓄電池１１を効果的に冷却してその温度上昇を抑制することができ、高い環境温度での充電効率を向上できる。
【００４１】
以下、各実験例について説明する。
【００４２】
（実験例１）
上記実施形態で示したような基本構成で、容量が１００Ａｈの大型の角形ニッケル水素蓄電池において、正極材料の組成として、ＣｏとＣｏＯの何れを含むか、またＹｂ_２Ｏ_３の含有量を変えた実施例１〜実施例３、比較例１、比較例２の各蓄電池について、５５℃での高温充電効率（２５℃での充電効率に対する比率（％）で表示する。）を調べた。
【００４３】
これら実施例１〜実施例３、比較例１、比較例２の各蓄電池の正極材料の組成と、その高温充電効率を表１に示す。
【００４４】
【表１】

表１から、ＣｏＯを含み、Ｃｏを含まない比較例２は、Ｙｂ_２Ｏ_３を含んでいても高温充電効率が低く、またＣｏを含んでいてもＹｂ_２Ｏ_３を含まない比較例１も高温充電効率が低いため、両者を含むことで高い高温充電効率が得られることが分かる。また、Ｙｂ_２Ｏ_３の含有量が１重量部の実施例３では充電効率が８０％で、比較例に比して格段に充電効率が向上しており、特に４、６重量部の実施例１、２では９０％という十分に高い充電効率が確保されている。
【００４５】
Ｃｏの含有量についても、Ｃｏの含有量を変化させて高温充電効率を調べたところ、３重量部では十分な高温充電効率が得られず、４〜８重量部で、８０〜９０％以上の高温充電効率が得られた。
【００４６】
（実験例２）
次に、大型の角形電池以外の大型円筒形蓄電池や小型円筒形蓄電池や鉛蓄電池との比較実験を行った。即ち、上記実施例２、比較例１、２の他に、容量が１００Ａｈの大型の円筒形蓄電池において、正極材料にＣｏとＹｂ_２Ｏ_３を含有させた比較例３と、容量が２Ａｈの小型の円筒形蓄電池において、正極材料にＣｏに代えてＣｏＯを含有させるとともにＹｂ_２Ｏ_３を含有させた比較例４と、同じ容積を占める、容量が６０Ａｈの鉛蓄電池から成る比較例５について、高温充電効率を調べた。その結果を表２に示す。
【００４７】
【表２】

表２から、Ｃｏ又はＹｂ_２Ｏ_３を含有しない大型角形蓄電池の比較例１、２は上記のように高温充電効率が低く、比較例３の大型の円筒形蓄電池においてはＣｏとＹｂ_２Ｏ_３の両方を含有していても高温充電効率が低い。これは中心部の発熱が外部に伝達され難いため高温になり、高温充電特性が低下したものと考えられる。また、比較例４の小型の円筒形蓄電池においてはＣｏＯをＹｂ_２Ｏ_３とともに含有していても、高い高温充電特性を示している。これは、極板での通電距離が短く、抵抗が小さいためであると考えられる。しかし、小容量であるため、多数の蓄電池を接続する必要があり、その接続抵抗が大きくなって温度上昇を来すことになる。また、比較例５の鉛蓄電池は、高温充電効率が高いが、同じ容積で容量が２／３であり、省容積化の要請に反する。
【００４８】
（実験例３）
次に、電解液の組成を変化させて高温充電効率の変化を見るため、正極材料として上記実施例２と同一の組成にしたものを用い、ＮａＯＨの（ＮａＯＨ＋ＫＯＨ）に対する比率（モル比）に関して、７０％の実施例２と、５０％と９０％と１００％の実施例４、５、６と、３０％、０％の比較例６、７について高温充電効率を調べた。その結果を表３に示す。なお、電解液の濃度は７．５ｍｏｌ／Ｌに統一し、３成分の残りであるＬｉＯＨは、０．５ｍｏｌ／Ｌとした。ＬｉＯＨが、１．０ｍｏｌ／Ｌでも同様の傾向が得られた。
【００４９】
【表３】

表３から、ＮａＯＨ≧ＫＯＨで、８０％以上の高い高温充電効率が得られ、特にＮａＯＨ＞ＫＯＨとすることで、９０％以上の高い高温充電効率が得られることが分かる。
【００５０】
（実験例４）
次に、Ｙｂ_２Ｏ_３の含有による高温充電効率の向上効果が大容量の蓄電池で効果が大きいことを見るため、容量が２、８、３０、１００Ａｈの角形蓄電池について、正極材料にＣｏのみを含有するものと、ＣｏとＹｂ_２Ｏ_３の両方を含有するものについてそれぞれ高温充電効率を調べた。その結果を表４と図７に示す。
【００５１】
【表４】

表４及び図７から、容量が小さいものはＣｏのみを含有するだけでもある程度高い高温充電効率が得られるが、３０Ａｈ以上の大容量になるとＣｏのみを含有するだけでは、高温充電効率が大幅に低下するとともに、Ｙｂ_２Ｏ_３を含有させることで高温充電効率が大幅に改善されることが分かる。
【００５２】
（実験例５）
次に、蓄電池（セル）を多数並列配置した場合に、それらの間に冷却風を送風することによる高温充電効率の改善効果をみるため、セル数が１と１０と８０の場合に、無送風と、１ｍ／ｓ、３ｍ／ｓ、６ｍ／ｓで送風した場合の高温充電効率を調べた。その結果を表５に示す。
【００５３】
【表５】

表５から、１セルでの充電では送風が無くても、高い高温充電効率が確保されているが、１０セル以上では１ｍ／ｓ以上、好適には３ｍ／ｓ以上の送風を行って冷却することで、高い高温充電効率が確保され、この１０セルモジュールを複数個組み合わせた場合も同様である。なお、送風には、ファンを用いると圧損が少なく好適であり、クロスフロー式やシロッコ式がより好適である。
【００５４】
【発明の効果】
本発明のバックアップ用角形蓄電池によれば、水酸化ニッケルを主体とする正極材料を含む正極板と水素吸蔵合金を主体とする負極材料を含む負極板とをセパレータを介して積層してなる極板群を電解液とともに角形電槽内に収容して成る角形ニッケル水素蓄電池から成り、角形電槽の一面に正極と負極の外部端子を配設し、各外部端子は角形電槽の貫通部で複数のＯリングにて二重にシールしているので、高温の環境温度で長期間使用しても確実に液漏れを防止することができ、また正極材料に、少なくともＣｏとＹｂ_２Ｏ_３を含むので、角形で大容量の蓄電池において正極板の各部位とリード部までの距離が長くなってもＣｏの含有によって正極板の抵抗を小さくできて充電効率を向上できるとともに、バックアップ用であるため絶えず満充電状態に維持されることからＣｏを含んでいても微小短絡によって寿命低下を来すというような弊害を生じることもなく、また正極材料にＹｂ_２Ｏ_３を含んでいることで高温域の充電効率を飛躍的に向上することができる。
【００５５】
また、電解液の組成をＮａＯＨ≧ＫＯＨ＞ＬｉＯＨとすると、高温での抵抗値の低いＮａＯＨの量が多いことで、高温充電効率の特性を全体的に高温側にシフトでき、高温域での充電効率を向上することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態のバックアップ用角形蓄電池を適用する、通信基地局における電源バックアップシステムの概略構成図である。
【図２】同実施形態のバックアップ用電源の配置構成を示し、（ａ）は部分縦断正面図、（ｂ）は縦断側面図である。
【図３】同実施形態の電池モジュールの斜視図である。
【図４】同実施形態の角形ニッケル水素蓄電池を、電槽の一部を破断して示した斜視図である。
【図５】同実施形態の角形ニッケル水素蓄電池における外部端子の装着構成を示す縦断面図である。
【図６】同実施形態と従来例の角形ニッケル水素蓄電池における温度変化に伴う充電効率の変化を模式的に示す特性図である。
【図７】本発明と従来例における電池容量と充電効率の関係を示すグラフである。
【符号の説明】
１１　角形ニッケル水素蓄電池
１２　電池モジュール
２０　極板群
２１　正極板
２２　負極板
２３　セパレータ
２４　電槽
２７　正極端子（外部端子）
２８　負極端子（外部端子）
３０ａ　冷却通路
４２　環状パッキン（Ｏリング）
４５　環状パッキン（Ｏリング）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a backup prismatic storage battery, and more particularly to a backup prismatic storage battery that is made of a nickel metal hydride storage battery and has a large capacity and a desired charging efficiency even under a high environmental temperature.
[0002]
[Prior art]
Conventionally, for example, as a backup storage battery in a communication base station, a lead storage battery has been generally used. However, in recent years, the multi-functionality of base station functions has progressed, and accordingly, it has been demanded to increase the power capacity to several tens to hundreds of tens Ah. If so, there is a problem that the volume and weight become too large, which is contrary to the demand for further downsizing. In addition, in consideration of environmental problems, it is desired to use a storage battery that does not contain lead or cadmium.
[0003]
Therefore, it is conceivable to use an AA cylindrical nickel-metal hydride battery for consumer use. That is, it is conceivable to secure a desired output voltage and capacity by connecting a plurality of battery modules configured by connecting a plurality of nickel metal hydride batteries in series and in parallel, but it is necessary to connect a large number of batteries. Therefore, there is a problem that the configuration becomes complicated and the cost is increased.
[0004]
In addition, since the terminals of many nickel metal hydride batteries are connected to each other, the connection resistance increases, causing a voltage drop at high output, and the amount of heat generation increases to increase the environmental temperature, further reducing the charging efficiency. There's a problem. In particular, a backup storage battery in a communication base station is required to have a clean atmosphere so as not to adversely affect the device, and for safety reasons, it is disposed in a substantially sealed space together with the device. This is a fatal problem because the outside air cannot be introduced and cooled as it is, and the environmental temperature tends to be high originally.
[0005]
Furthermore, it is conceivable to construct a large-sized cylindrical nickel-metal hydride battery with a relatively large capacity to simplify the structure and reduce the cost, and to reduce the connection resistance. There is a problem that charging efficiency is lowered because heat is not sufficiently released and the temperature becomes high.
[0006]
Therefore, an electrode plate group formed by laminating a positive electrode plate including a positive electrode material mainly composed of nickel hydroxide and a negative electrode plate including a negative electrode material mainly composed of a hydrogen storage alloy through a separator is formed in a rectangular battery case together with an electrolyte. It is conceivable to apply a relatively large capacity prismatic nickel metal hydride storage battery accommodated in such a backup storage battery.
[0007]
In this type of prismatic nickel metal hydride storage battery, a positive electrode material obtained by adding CoO to nickel hydroxide to improve conductivity is known. It should be noted that it is more effective to add metal Co to improve conductivity, but if it is left in a discharged state, a short circuit occurs and the life is shortened, so CoO is added instead of Co. Yes. Further, the electrolytic solution is composed of three components of KOH, NaOH, and LiOH, and the composition ratio thereof is KOH that provides a low resistance value such as KOH: NaOH: LiOH = 4: 2.5: 1. In general, the amount of KOH>NaOH> LiOH is used (see, for example, Patent Document 1).
[0008]
Moreover, the penetration part of the battery case upper wall of the connection terminal of the positive electrode and negative electrode which are arrange | positioned on the battery case upper surface is sealed by the single annular packing (for example, refer patent document 2).
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-4502
[Patent Document 2]
JP-A-10-188944 (2nd, 4th, 5th pages, FIG. 2)
[0011]
[Problems to be solved by the invention]
However, in the configuration of the conventional prismatic nickel metal hydride storage battery, since the connection terminal is a portion that penetrates the upper wall and is sealed only by a single annular packing, as a backup power source, as described above. When exposed to a high ambient temperature for a long time, there is a problem that liquid leakage may occur from the penetrating portion.
[0012]
Further, since the backup storage battery has a high environmental temperature, it is required that the charging efficiency at a high temperature is sufficiently high. However, the conventional prismatic nickel metal hydride storage battery has a problem that the charging efficiency at a high temperature rapidly decreases. Turned out to be. For example, assuming that the charging efficiency at 25 ° C. is 100%, it becomes about 50 to 60% at 55 ° C., for example, the required charge of 80 Ah or more at −10 ° C. and 90 Ah or more at 55 ° C. with a storage battery having a capacity of 100 Ah. There is a problem that the capacity cannot be satisfied.
[0013]
In view of the above-described conventional problems, the present invention provides a backup prismatic storage battery comprising a nickel-metal hydride storage battery that can obtain a desired charging efficiency even in a state where the capacity is large and the environmental temperature is high, and can reliably prevent the occurrence of liquid leakage. The purpose is to do.
[0014]
[Means for Solving the Problems]
The square prismatic battery for backup of the present invention comprises an electrode plate group in which a positive electrode plate including a positive electrode material mainly composed of nickel hydroxide and a negative electrode plate including a negative electrode material mainly composed of a hydrogen storage alloy are stacked via a separator. It consists of a prismatic nickel-metal hydride storage battery that is housed in a rectangular battery case together with the electrolyte. The positive and negative external terminals are arranged on one side of the rectangular battery case. Double sealing is performed with packing, and the positive electrode material contains at least Co and Yb compounds.
[0015]
According to this configuration, the penetrating part of the rectangular battery case of the external terminal is double-sealed with a plurality of annular packings, so that liquid leakage can be reliably prevented even when used for a long time at a high ambient temperature. Can do. In addition, even if the distance between each part of the positive electrode plate and the lead part is increased in a rectangular and large capacity storage battery, the positive electrode material contains Co, so that the resistance can be reduced and the charging efficiency can be improved. Therefore, even if it contains metal Co, it will not be left in a discharged state even if it contains metal Co. Therefore, there is a problem that the life is shortened by a micro short circuit. There is nothing. Moreover, the charging efficiency in a high temperature region can be improved dramatically by including the Yb compound in the positive electrode material. As the Yb compound, Yb ₂ O ₃ is suitable, but the same action can be obtained with Yb (OH) ₃ .
[0016]
The Co content is preferably 4 to 8 parts by weight with respect to 100 parts by weight of nickel hydroxide, and the Yb compound content is preferably 1 to 6 parts by weight with respect to 100 parts by weight of nickel hydroxide. . If the Co content is less than 4 parts by weight, the above-mentioned resistance reduction effect is not sufficient. If the Co content exceeds 8 parts by weight, the amount of nickel hydroxide is relatively decreased, so that the capacity per fixed volume is decreased. Further, if the content of the Yb compound is less than 1 part by weight, the effect of improving the high-temperature charging efficiency cannot be sufficiently obtained, and if it exceeds 6 parts by weight, the amount of nickel hydroxide is relatively decreased, so the capacity per fixed volume. Will drop. The optimum content is 5 parts by weight of Co and 4 parts by weight of the Yb compound.
[0017]
Furthermore, if the electrolytic solution is composed of three components of NaOH, KOH, and LiOH, and the composition is NaOH ≧ KOH> LiOH, the amount of NaOH having a low resistance value at high temperature is large, so that the characteristics of high-temperature charging efficiency are as a whole. Thus, the temperature can be shifted to the high temperature side, and the charging efficiency in the high temperature range can be improved.
[0018]
In addition, if the square battery case is made of synthetic resin, when an abnormal reaction occurs in which the temperature and internal pressure of the storage battery suddenly rises, the battery case softens before the internal pressure increases. Since gas can be released without fear and insulation of the external terminal portion can be easily ensured, high safety can be ensured when a large amount of storage batteries are used as a system.
[0019]
The above configuration is particularly effective in a storage battery having a large capacity of 30 Ah or more.
[0020]
In addition, when a plurality of backup prismatic storage batteries having the above-mentioned configuration are connected in series and are integrally coupled in a state where a cooling passage is provided between the backup prismatic nickel metal hydride storage batteries, the output voltage is reduced. While being able to make it high, each storage battery can be cooled effectively and a temperature rise can be suppressed, and even if atmospheric temperature is high, high charging efficiency can be ensured.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the backup prismatic storage battery of the present invention will be described with reference to FIGS.
[0022]
First, a schematic configuration of a power supply backup system in a communication base station to which the backup rectangular storage battery of the present embodiment is applied will be described with reference to FIG. In FIG. 1, a pair of power sources 1 are configured to supply power to a load 3 composed of various base station devices via a rectifier 2 and are connected in parallel between the rectifier 2 and the load 3. The backup power supply circuit 4 in which the battery packs 5a and 5b and the discharge control means 6 are connected in series is connected in parallel. The battery packs 5a and 5b are provided with a cooling fan 7 for blowing cooling air for suppressing temperature rise. Moreover, the charging means 8 is connected between the rectifier 2 and the battery packs 5a and 5b so that the battery packs 5a and 5b are charged.
[0023]
The voltage, current, and temperature in the battery packs 5a and 5b are detected, and the voltage information, current information, and temperature information are input to the battery monitoring unit 9 to monitor the state of the battery. The battery monitoring unit 9 calculates the amount of electricity (SOC) of the battery packs 5a and 5b, and performs a charge request, a charge stop request, a discharge availability notification, a battery state notification, safety control, and an operation control of the cooling fan 7. The monitoring information is input from the battery monitoring unit 9 to the control unit 10, and the control unit 10 is configured to control the rectifier 2, the charging unit 8, and the discharge control unit 6 in accordance with the state of the battery packs 5a and 5b. Yes. The pair of

battery packs

5a and 5b are provided so that power can be reliably supplied even when the commercial power supply 1 is interrupted during any maintenance, and charging to the battery packs 5a and 5b is performed at appropriate time intervals. In addition, the battery packs 5a and 5b are configured so as to be almost in a fully charged state by being alternately performed so that the charging periods for the battery packs 5a and 5b are different from each other.
[0024]
As shown in FIGS. 2A and 2B, each of the battery packs 5a and 5b constitutes a battery module 12 by arranging 10 prismatic nickel metal hydride storage batteries 11 in parallel and constraining them integrally. Four battery modules 12 are arranged in parallel. The output voltage of the battery packs 5a and 5b is set to 48V by connecting four battery modules 12 connected in series by connecting 10 rectangular nickel-metal hydride storage batteries 11 having an output voltage of 1.2V in series. .
[0025]
Each of the battery packs 5a and 5b is arranged in a backup power supply arrangement space 15 formed in the lower part of the casing 13 provided with a base station device arrangement space 14 in the upper part, and a cooling air passage 16a in the lower and upper parts thereof. 16b are provided. That is, each battery module 12 constituting the battery packs 5a and 5b is installed on a support bar 17 provided with a cooling air passage 16a in the lower part. A blower fan 7 is disposed at one end of the lower cooling air passage 16a so that the cooling air is introduced through a filter 18 and is discharged from an exhaust grill 19 disposed at one end of the upper cooling air passage 16b. It is configured.
[0026]
As shown in FIG. 3, each battery module 12 is arranged with 10 nickel metal hydride prismatic batteries 11 (11 a to 11 j) so that the long long sides of the battery case face each other and overlap each other. The end plates 32 are brought into contact with the outside of the battery case of the unit cells 11a, 11j, and the

end plates

32, 32 are bound together by a restraining band 33 so as to be integrally connected.
[0027]
As shown in FIGS. 4 and 5, each nickel metal hydride storage battery 11 accommodates an electrode plate group 20 formed by laminating a positive electrode plate 21 and a negative electrode plate 22 with a separator 23 in a battery case 24 together with an electrolytic solution. Then, the opening of each battery case 24 is closed with a lid 25 provided with a safety valve 26, the lead 29 is drawn upward from the upper end of one side of each positive electrode plate 21 constituting the electrode plate group 20, and the positive electrode terminal 27 is connected to the upper part thereof. Similarly, lead 29 is drawn upward from the upper end of the other side of each negative electrode plate 22, and negative electrode terminal 28 is connected to the upper part thereof. Positive electrode terminal 27 and negative electrode terminal 28 as external terminals are attached to lid 25. Configured. The size and the number of stacked plates of the positive electrode plate 21 and the negative electrode plate 22 of the electrode plate group 20 are designed so as to obtain a capacity of, for example, 100 Ah. In this case, the distance between the lower end and the upper end is 100 to 100 mm, for example. It becomes about 150 mm.
[0028]
And in each battery module 12, the positive electrode terminal 27 and the negative electrode terminal 28 between adjacent nickel hydrogen

prismatic storage batteries

11 and 11 are connected by the connection board 31, and each nickel hydrogen prismatic storage battery 11 is connected in series. Moreover, when each

battery case

24 and 24 is joined, the rib 30 projected in the up-down direction on the long side surface of the battery case 24 is faced | matched between adjacent, and the space between the long side surfaces between each

rib

30 and 30 is carried out. The cooling passage 30a penetrating in the vertical direction of the battery case 24 is formed, and the nickel hydrogen prismatic batteries 11a to 11j are cooled by blowing air to the cooling passage 30a.
[0029]
As shown in FIG. 5, the positive electrode terminal 27 and the negative electrode terminal 28 are provided with a connecting screw part 36 at the upper part of a pole part 35 that penetrates the terminal through hole 34 formed in the lid 25, and at the lower part, a rectangular flange. A portion 37 is formed, and a plurality of current collecting rods 38 are suspended from the lower surface of the flange portion 37 at appropriate intervals. A washer 39 is disposed around the terminal through-hole 34 on the upper surface of the lid 26, and the inner peripheral edge of the annular pressing spring 40 disposed on the washer 39 is elastically locked to the outer peripheral surface of the pole portion 35, whereby these

terminals

27 and 28 are fixed to the lid 25.
[0030]
An annular sealing groove 41 is formed on the upper surface of the flange portion 37 and an annular packing 42 such as an O-ring is accommodated and disposed, and a sealing agent 43 such as a pitch is filled and disposed, and the lower surface of the lid 25 and this sealing groove are disposed. The annular packing 42 is compressed between 41, and the first-stage sealing is performed with the sealing agent 43 filled in the periphery thereof. Further, a taper seal surface 44 is formed on the upper portion of the terminal through hole 34, and an annular packing 45 such as an O-ring is disposed. By compressing the annular packing 45 between the taper seal surface 44 and the washer 39, the second stage is achieved. Sealing is performed, and double sealing is performed by the

annular packings

42 and 45.
[0031]
A lead 29 is electrically connected to a current collecting rod 38 suspended from the flange portion 37 by laser beam welding or electron beam welding. Further, both side end surfaces 37 a of the flange portion 37 are engaged with positioning protrusions 46 provided on the lid 25, and are configured to perform a detent function when the connection plate 31 is fastened to the screw portion 36.
[0032]
The positive electrode plate 21 constituting the electrode plate group 20 of the nickel metal hydride storage battery 11 is nickel hydroxide (in the present invention, Ni (OH) ₂ is also referred to as a material in which Cо or the like is dissolved or coated). The negative electrode plate 22 is configured by coating and holding a negative electrode material mainly composed of a hydrogen storage alloy on a Ni punching metal, and the separator 23 is formed of a polyamide or polyolefin. It is composed of a non-woven fabric.
[0033]
In this embodiment, the positive electrode material mainly composed of nickel hydroxide contains at least Co and a Yb compound such as Yb ₂ O ₃ or Yb (OH) ₃ . Specifically, Co is contained in 4 to 8 parts by weight with respect to 100 parts by weight of Ni (OH) ₂ , and the Yb compound is contained in 1 to 6 parts by weight. Specifically, Ni (OH) ₂ : 100 parts by weight, Co: 5 parts by weight, Co (OH) ₂ : 5 parts by weight, Yb ₂ O ₃ : 4 parts by weight, ZnO: 2.5 parts by weight A positive electrode material is constructed.
[0034]
The electrolytic solution is composed of a mixed solution of three components of NaOH, KOH, and LiOH, and the composition satisfies NaOH ≧ KOH> LiOH. As a specific example, the composition ratio of the electrolytic solution is NaOH: KOH: LiOH = 4: 2.5: 1. In addition, the density | concentration of electrolyte solution is 7.5 mol / L.
[0035]
In the prismatic nickel metal hydride storage battery 11 having the above-described configuration, the positive electrode terminal 27 and the negative electrode terminal 28 are disposed on the upper surface of the rectangular battery case 24, and a plurality of these

terminals

27 and 28 are provided at the through portion of the lid 25 of the battery case 24. Double sealing with the

annular packings

42 and 45 prevents liquid leakage even if it is placed in the backup power source placement space 15 that may be an environmental temperature as high as 55 ° C. and used for a long time. It can be surely prevented, and it is possible to prevent the occurrence of a short circuit due to leakage and secure high safety.
[0036]
Further, since the positive electrode material of the positive electrode plate 21 contains Co, even if the distance from the lower end to the upper end of the positive electrode plate 21 is as large as about 100 to 150 mm, the resistance of the positive electrode plate 21 due to the presence of highly conductive metal Co. The charging efficiency can be improved. In addition, even if it contains metal Co in this way, it is used for backup, so it is constantly maintained in a fully charged state and will not be left in a discharged state. There is no such negative effect.
[0037]
In addition, by including the Yb compound in the positive electrode material of the positive electrode plate 21, the charging efficiency in the high temperature region can be dramatically improved.
[0038]
Furthermore, the electrolytic solution is composed of three components of NaOH, KOH, and LiOH, the composition of which is NaOH: KOH: LiOH = 4: 2.5: 1, and the amount of NaOH having a low resistance value at a high temperature is increased. Therefore, the characteristics of the high temperature charging efficiency can be shifted to the high temperature side as a whole, and the charging efficiency in the high temperature region can be improved. Increasing the amount of NaOH is contrary to the output characteristics, but does not cause a problem in the use of a backup power source.
[0039]
Thus, by using the prismatic nickel metal hydride storage battery 11 having a capacity of 100 Ah, it was possible to secure a capacity of 80 Ah or more at −10 ° C. and 90 Ah or more at 55 ° C. as shown in FIG. In FIG. 6, for comparison, the case of a conventional example that contains CoO instead of Co and does not contain Yb ₂ O ₃ is indicated by a broken line.
[0040]
Further, in each battery module 12 in which a plurality of the prismatic nickel metal hydride storage batteries 11 are arranged in parallel and integrally coupled, the cooling passage 30a is formed between the prismatic nickel metal

hydride storage batteries

11, 11, so that each storage battery 11 is effectively used. Therefore, the temperature rise can be suppressed and the charging efficiency at a high environmental temperature can be improved.
[0041]
Hereinafter, each experimental example will be described.
[0042]
(Experimental example 1)
In the large prismatic nickel metal hydride storage battery having a basic configuration as shown in the above embodiment and having a capacity of 100 Ah, the composition of the positive electrode material includes either Co or CoO, and the content of Yb ₂ O ₃ is changed. For each of the storage batteries of Examples 1 to 3, Comparative Example 1, and Comparative Example 2, the high temperature charging efficiency at 55 ° C. (displayed as a ratio (%) to the charging efficiency at 25 ° C.) was examined.
[0043]
Table 1 shows the composition of the positive electrode material of each of the storage batteries of Examples 1 to 3, Comparative Example 1 and Comparative Example 2 and the high-temperature charging efficiency thereof.
[0044]
[Table 1]

From Table 1, comprises CoO, Comparative Example 2 containing no Co also contain _Yb 2 _{O 3} low high-temperature charging efficiency and also Comparative Example 1 also comprise Co does not contain _Yb 2 _{O 3} Since high temperature charging efficiency is low, it turns out that high high temperature charging efficiency is obtained by including both. Further, in Example 3 in which the content of Yb ₂ O ₃ is 1 part by weight, the charging efficiency is 80%, and the charging efficiency is remarkably improved as compared with the comparative example. For 1 and 2, sufficiently high charging efficiency of 90% is secured.
[0045]
As for the Co content, the high temperature charging efficiency was examined by changing the Co content. As a result, sufficient high temperature charging efficiency was not obtained with 3 parts by weight, and 80 to 90% or more with 4 to 8 parts by weight. High temperature charging efficiency was obtained.
[0046]
(Experimental example 2)
Next, comparative experiments were conducted with large cylindrical batteries, small cylindrical batteries, and lead batteries other than large prismatic batteries. That is, in addition to Example 2 and Comparative Examples 1 and 2, in a large cylindrical storage battery with a capacity of 100 Ah, Comparative Example 3 in which the positive electrode material contains Co and Yb ₂ O ₃ and a small capacity with a capacity of 2 Ah. In Comparative Example 4 in which the positive electrode material contains CoO instead of Co and Yb ₂ O ₃ and Comparative Example 5 which occupies the same volume and which consists of a lead storage battery with a capacity of 60 Ah, The charging efficiency was examined. The results are shown in Table 2.
[0047]
[Table 2]

From Table 2, Comparative Examples 1 and 2 of the large prismatic batteries not containing Co or Yb ₂ O ₃ have low high-temperature charging efficiency as described above, and in the large cylindrical battery of Comparative Example 3, Co and Yb ₂ O ₃ Even if both are contained, the high-temperature charging efficiency is low. This is probably because the heat generated at the center is difficult to be transmitted to the outside, resulting in a high temperature and a deterioration in the high temperature charging characteristics. Further, in the cylindrical battery of small Comparative Example 4 also contain CoO with Yb ₂ O _3, shows high high-temperature charging characteristics. This is considered to be because the energization distance at the electrode plate is short and the resistance is small. However, since it has a small capacity, it is necessary to connect a large number of storage batteries, and the connection resistance increases and the temperature rises. Moreover, although the lead acid battery of the comparative example 5 has high high-temperature charging efficiency, it has the same volume and a capacity of 2/3, which is contrary to the demand for volume saving.
[0048]
(Experimental example 3)
Next, in order to see the change in the high-temperature charging efficiency by changing the composition of the electrolytic solution, the positive electrode material having the same composition as in Example 2 was used, and the ratio (molar ratio) of NaOH to (NaOH + KOH) The high-temperature charging efficiency was examined for 70% of Example 2, 50%, 90%, and 100% of Examples 4, 5, and 6, and Comparative Examples 6 and 7 of 30% and 0%. The results are shown in Table 3. In addition, the density | concentration of electrolyte solution was unified to 7.5 mol / L, and LiOH which is the remainder of 3 components was 0.5 mol / L. The same tendency was obtained even when LiOH was 1.0 mol / L.
[0049]
[Table 3]

From Table 3, it can be seen that a high temperature charging efficiency of 80% or higher is obtained when NaOH ≧ KOH, and a high high temperature charging efficiency of 90% or higher is obtained particularly when NaOH> KOH.
[0050]
(Experimental example 4)
Next, in order to see that the effect of improving the high-temperature charging efficiency due to the inclusion of Yb ₂ O ₃ is large in a large-capacity storage battery, for a rectangular storage battery with a capacity of 2, 8, 30, 100 Ah, only Co is used as the positive electrode material. The high-temperature charging efficiency was examined for each of those containing and those containing both Co and Yb ₂ O ₃ . The results are shown in Table 4 and FIG.
[0051]
[Table 4]

From Table 4 and FIG. 7, high capacity charging efficiency can be obtained to some extent even if it contains only Co, but if it has a large capacity of 30 Ah or more, high temperature charging efficiency can be greatly improved if only Co is contained. It can be seen that the high temperature charging efficiency is greatly improved by containing Yb ₂ O ₃ as well as decreasing.
[0052]
(Experimental example 5)
Next, when a large number of storage batteries (cells) are arranged in parallel, in order to see the effect of improving the high-temperature charging efficiency by blowing cooling air between them, when the number of cells is 1, 10 and 80, no ventilation The high-temperature charging efficiency when the air was blown at 1 m / s, 3 m / s, and 6 m / s was examined. The results are shown in Table 5.
[0053]
[Table 5]

From Table 5, high-temperature charging efficiency is ensured even when there is no ventilation in charging with 1 cell, but cooling is performed by blowing air of 1 m / s or more, preferably 3 m / s or more in 10 cells or more. Thus, high high-temperature charging efficiency is ensured, and the same applies when a plurality of 10-cell modules are combined. Note that a fan is preferably used for blowing air with less pressure loss, and a cross flow type or a sirocco type is more preferable.
[0054]
【The invention's effect】
According to the backup prismatic storage battery of the present invention, an electrode plate obtained by laminating a positive electrode plate including a positive electrode material mainly composed of nickel hydroxide and a negative electrode plate including a negative electrode material mainly composed of a hydrogen storage alloy via a separator. It consists of a prismatic nickel metal hydride storage battery that is housed in a rectangular battery case together with an electrolytic solution. Positive and negative external terminals are arranged on one side of the rectangular battery case, and there are multiple external terminals at the penetrating part of the rectangular battery case. The O-ring is double sealed so that liquid leakage can be reliably prevented even when used for a long time at a high ambient temperature, and the positive electrode material contains at least Co and Yb ₂ O ₃ . Therefore, in a square and large capacity storage battery, even if the distance between each part of the positive electrode plate and the lead portion is increased, the inclusion of Co can reduce the resistance of the positive electrode plate and improve the charging efficiency. It without causing adverse effects such as that fully cause a reduction in service life by a micro short circuit also contain Co from which it is maintained in a charged state and a high temperature range by containing the Yb ₂ O ₃ to a positive electrode material Charging efficiency can be dramatically improved.
[0055]
Moreover, when the composition of the electrolyte is NaOH ≧ KOH> LiOH, the amount of NaOH having a low resistance value at high temperature is large, so that the characteristics of high temperature charging efficiency can be shifted to the high temperature side as a whole, and charging in a high temperature range is possible. Efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a power supply backup system in a communication base station to which a backup prismatic storage battery according to an embodiment of the present invention is applied.
2A and 2B show an arrangement configuration of a backup power source according to the embodiment, in which FIG. 2A is a partially longitudinal front view, and FIG. 2B is a longitudinal side view;
FIG. 3 is a perspective view of the battery module of the same embodiment.
FIG. 4 is a perspective view showing the prismatic nickel metal hydride storage battery of the same embodiment with a part of the battery case cut away.
FIG. 5 is a longitudinal sectional view showing a mounting configuration of external terminals in the prismatic nickel metal hydride storage battery of the same embodiment.
FIG. 6 is a characteristic diagram schematically showing a change in charging efficiency accompanying a temperature change in the prismatic nickel metal hydride storage battery of the embodiment and the conventional example.
FIG. 7 is a graph showing the relationship between battery capacity and charging efficiency in the present invention and a conventional example.
[Explanation of symbols]
11 prismatic nickel metal hydride storage battery 12 battery module 20 electrode plate group 21 positive electrode plate 22 negative electrode plate 23 separator 24 battery case 27 positive electrode terminal (external terminal)
28 Negative terminal (external terminal)
30a Cooling passage 42 Annular packing (O-ring)
45 Ring packing (O-ring)

Claims

A plate group made by laminating a positive electrode plate including a positive electrode material mainly composed of nickel hydroxide and a negative electrode plate including a negative electrode material mainly composed of a hydrogen storage alloy through a separator is accommodated in a rectangular battery case together with an electrolyte. The positive and negative external terminals are arranged on one side of the rectangular battery case, and each external terminal is double sealed with a plurality of annular packings at the penetrating part of the rectangular battery case, A back-up prismatic storage battery characterized in that the positive electrode material contains at least Co and a Yb compound.

The Co content is 4 to 8 parts by weight with respect to 100 parts by weight of nickel hydroxide, and the Yb compound content is 1 to 6 parts by weight with respect to 100 parts by weight of nickel hydroxide. The backup rectangular storage battery according to claim 1.

3. The backup prismatic storage battery according to claim 1, wherein the electrolytic solution is composed of three components of NaOH, KOH, and LiOH, and the composition is NaOH ≧ KOH> LiOH.

The square battery for backup according to any one of claims 1 to 3, wherein the rectangular battery case is made of synthetic resin.

5. The backup prismatic storage battery according to claim 1, wherein the capacity is 30 Ah or more.

A plurality of backup prismatic storage batteries according to any one of claims 1 to 5, wherein the backup prismatic storage batteries are connected in series, and are integrally coupled in a state where a cooling passage is provided between the backup prismatic nickel metal hydride storage batteries. Square storage battery module.