JP3579621B2

JP3579621B2 - Battery pack

Info

Publication number: JP3579621B2
Application number: JP25783499A
Authority: JP
Inventors: 克巳高津; 茂梶原
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1998-09-11
Filing date: 1999-09-10
Publication date: 2004-10-20
Anticipated expiration: 2019-09-10
Also published as: JP2000149893A

Description

【０００１】
【発明の属する技術分野】
本発明は、携帯電話機やモバイルコンピュータ等の携帯情報機器の電池電源として用いられる電池パックに関するものである。
【０００２】
【従来の技術】
図１３（ａ）は、従来構成になる携帯電話機の電池パック４９収容部分の内部構成を示すもので、パックケース５０内にリチウムイオン二次電池により形成された電池５１を収容すると共に、この電池５１を過充電や過放電等から保護するための電池保護装置５２を備えて構成されている。この電池５１は、発電要素を収容した電池缶６１が負極端子、電池缶を封口した封口板６２に正極端子を設けて構成されている。従って、負極端子及び正極端子と電池保護装置５２との間は、図示するように正極接続リード５３、負極接続リード５４により電気的な接続がなされる。また、正極接続リード５３及び負極接続リード５４はリチウムイオン二次電池５１上に電池保護装置５２を保持する支持部材としての機能を担っている。前記正極接続リード５３は、その一端がリチウムイオン二次電池５１の正極端子にスポット溶接され、負極端子である電池缶６１との間の絶縁を確保するため電池缶６１上に貼着された絶縁シート５５上を延長して、その他端を保護回路が形成された回路基板５６にハンダ付けされている。負極接続リード５４は、その一端が電池缶６１の底面にスポット溶接され、他端が前記回路基板５６にハンダ付けされている。
【０００３】
前記電池保護装置５２は、過放電や過充電あるいは短絡等から電池５１を保護するために設けられているもので、電池５１は電池保護装置５２を介して外部出力端子５７ａ〜５７ｄに接続される。また、電池保護のための回路を形成した回路基板５６に、外部出力端子５７ａ〜５７ｄ及びテスト端子５８が取り付けられた端子支持板５９の外部出力端子５７ａ〜５７ｄ及びテスト端子５８を回路基板５６にハンダ付けすることにより、回路基板５６と端子支持板５９とを一体化して電池保護装置５２が構成される。図１３（ｂ）は、電池５１及び電池保護装置５２の反対面の構成を示している。外部出力端子５７ａ〜５７ｄには、電池パックを携帯電話機に装着したとき、携帯電話機に設けられた接続プローブが接触して電池パックの携帯電話機に対する電気的接続がなされる。テスト端子５８は、その延長端が電池缶６１との絶縁を確保する絶縁シート６０上に配置され、電池缶６１に一端がスポット溶接されたテスト片６２と共にパックケース５０に設けられた開口孔から露出して、電池保護装置５２の動作テストに用いられる。動作テストの終了後に前記開口孔は被覆シートにより閉じられる。
【０００４】
このように従来構成になる電池パック４９では、図１３（ｂ）に示すように、電池５１、電池保護装置５２、外部出力端子５７ａ〜５７ｄが一体的に形成され、これを図１３（ａ）に示すようにパックケース５０に収容することにより、前記外部出力端子５７ａ〜５７ｄがパックケース５０の開口部から外部に露出するように構成されている。
【０００５】
【発明が解決しようとする課題】
携帯電話機の小型化の進展は目ざましいものがあるが、次の発展課題は薄型化である。この薄型化は携帯電話機だけでなく、モバイルコンピュータや電子手帳等の携帯情報機器についても同様に要求される課題となっている。小型化だけでは携帯の便を必ずしも満たすことはできず、薄型化が達成されてこそ携帯性が向上し、携帯電話機では胸ポケットに違和感なく挿入できるポケットイン携帯を可能にする。
【０００６】
上記従来構成になる電池パック４９は、図１４に携帯電話機の電池装着位置の断面として示すように携帯電話機７０に装着されるが、電池パック４９が携帯電話機７０の厚さの約１／２を占めている。この電池パック４９の薄型化が携帯電話機７０の薄型化を達成するための重要な要素となっている。他の携帯情報機器についても同様の電池装着状態にあり、携帯情報機器の小型軽量化及び薄型化、特に薄型化を実現するには電池の薄型化が不可欠の要素となる。
【０００７】
しかしながら、従来の電池パック４９に用いられたリチウムイオン二次電池のように正負極板を金属製の電池缶に収容した電池では、電池缶を薄型化することに限界がある。また、図１３に示したように、電池の正極端子及び負極端子と電池保護装置との間の接続に多くの部材や加工工程を必要とし、電池以外の構成要素も電池パックの薄型化を阻害している。更に、電池保護装置５２の配設構造は、パックケース５０内の厚さ方向にスペースを要するものとなり、外部出力端子５７ａ〜５７ｄの支持構造が更に厚みを増長させてしまう問題点があった。
【０００８】
本発明が目的とするところは、正負電極を軟質材料によって形成された外装ケース内に収容して構成された電池を用いることにより薄型化を図ると共に、他の構成要素を電池の薄型形状に合わせて配設して、電池パックの薄型化を実現することにある。
【０００９】
【課題を解決するための手段】
上記目的を達成するための本願の第１発明は、偏平形状に形成された二次電池と、この二次電池を保護するための保護回路を形成した回路基板及びＰＴＣ素子を備えて構成された電池保護装置とを、収納容器となる下ケースと、この下ケースの開口側を閉じる蓋体をなす上ケースとを接合して偏平形状に形成されるパックケース内に収容し、前記二次電池から引き出された正極リード及び負極リードを前記電池保護装置を介してパックケースに設けられた外部出力端子に接続してなる電池パックにおいて、前記二次電池が、シート状の正負極板を積層して形成された発電要素を一対のラミネートシートの周辺部を溶着シールした外装ケース内に収容し、溶着シールした一辺側から正極リード及び負極リードが引き出されてなり、この二次電池の前記正極リード及び負極リードが引き出された一辺側に前記電池保護装置が配設されてなることを特徴とする。
【００１０】
この構成によれば、正負極板を積層構造にした二次電池は正極リード及び負極リードを外装ケースであるラミネートシートを溶着シールした一辺側から引き出すことができ、このリード引き出し辺側に電池保護装置を配設することにより、二次電池と電池保護装置との間の接続が最短距離でなされてシンプルな構造となり、構成部材や加工工程を削減すると共に、電池パックの薄型化を容易にする。
【００１１】
上記構成において、回路基板は、その板面方向が二次電池の偏平面方向と平行で、且つ外装ケースの溶着シール部分の少なくともその一部とオーバーラップした位置に配設されるので、電池保護装置を薄いパックケース内に収容し、且つ溶着シール部分の収容スペースを設けて電池パックの小型薄型化を達成することができる。
【００１２】
また、電池保護装置がパックケース内の下ケース寄りに配設され、この回路基板に接続された正極接続部材及び負極接続部材と、正極リード及び負極リードとが、ぞれぞれ上ケース寄りの位置で接続され、このリード接続位置と電池保護装置との間に電池の溶着シール部分が配設されるように構成することにより、電池保護装置上にリード接続位置を配しても溶着シール部分がその間に介在してリード接続部分と電池保護装置との間の絶縁を確保することができる。
【００１３】
また、回路基板は、基板の一方面を部品実装面、他方面をハンダ付け面として形成され、前記ハンダ付け面を下ケースの開放面側に向けて配設されるように構成することにより、ハンダ付け面に対する接続及び絶縁処理等を容易に行うことができる。
【００１４】
また、回路基板のハンダ付け面は、接続加工の終了後に絶縁素材により被覆されるように構成することにより、電池から電解液が漏出した場合に回路基板に液絡や腐食が生じることを防止することができる。
【００１５】
また、ＰＴＣ素子が板状に形成されてなり、その板面方向は二次電池の偏平面方向と平行で、且つ外装ケースの溶着シール部分の少なくともその一部とオーバーラップした位置に配設されるように構成することにより、薄いパックケース内に収容し、且つ溶着シール部分の収容スペースを設けて電池パックの小型薄型化を達成することができる。
【００１６】
また、本願の第２発明は、平板形状に形成された二次電池と、少なくとも二次電池を保護するための保護回路を形成した回路基板を備えて構成された電池保護装置とをパックケース内に収容し、前記二次電池から引き出された正極リード及び負極リードを前記電池保護装置を介してパックケースに設けられた正極外部出力端子及び負極外部出力端子に接続してなる電池パックにおいて、前記二次電池が、発電要素を一対のラミネートシートからなる外装ケース内に収容し、溶着シールした一辺側の溶着シール部分から正極リード及び負極リードが引き出されてなり、前記正極外部出力端子及び負極外部出力端子がパックケースのリード引き出し辺側の側面に装着固定されて配され、回路基板が、その板面方向が二次電池の平板面方向と平行で、且つ外装ケースの前記溶着シール部分の少なくともその一部とオーバーラップするように、前記二次電池と前記外部出力端子との間に配され、電池保護装置がパックケース内の厚さ方向の一方寄りに配設され、回路基板に接続された正極接続部材及び負極接続部材と正極リード及び負極リードがパックケース内の厚さ方向の他方寄りの位置で接続され、このリード接続位置と電池保護装置との間に外装ケースの前記溶着シール部分が配設され、前記正極外部出力端子及び負極外部出力端子が、それぞれの延出部において、回路基板に接続されていることを特徴とする。
【００１７】
この構成によれば、発電要素を構成する正極板及び負極板に接続された正極リード及び負極リードを外装ケースであるラミネートシートを溶着シールした一辺側から引き出し、このリード引き出し辺側のパックケース側面に装着固定された外部出力端子と二次電池との間に電池保護装置を配設することにより、二次電池と電池保護装置と外部出力端子との間の接続が最短距離でなされてシンプルな構造となり、構成部材や加工工程を削減すると共に、電池パックの薄型化を容易にする。
【００１８】
また、回路基板は、その板面方向が二次電池の平板面方向と平行で、且つ外装ケースの溶着シール部分の少なくともその一部とオーバーラップした位置に配設されるので、電池保護装置を薄いパックケース内に収容し、且つ溶着シール部分の収容スペースを設けて電池パックの小型薄型化を達成することができる。
【００１９】
また、電池保護装置がパックケース内の厚さ方向の一方寄りに配設され、回路基板に接続された正極接続部材及び負極接続部材と正極リード及び負極リードとがそれぞれパックケース内の厚さ方向の他方寄りの位置で接続され、このリード接続位置と電池保護装置との間に二次電池の溶着シール部分が配設されるように構成されているので、電池保護装置上にリード接続位置を配しても溶着シール部分がその間に介在してリード接続部分と電池保護装置との間の絶縁を確保することができる。
【００２０】
また、外装ケースの少なくとも溶着シール部分と電池保護装置との間に絶縁部材を配設して構成することにより、電池保護装置上にオーバーラップして配置される外装ケースの溶着シール部分が回路基板等に接触して、振動や衝撃が加わったときにラミネートシートの樹脂層が破壊されて金属層に導電部位が接触する事故が防止される。
【００２１】
また、電池保護装置がＰＴＣ素子を備えてなり、ＰＴＣ素子は板状に形成され、その板面方向が二次電池の平板面方向と平行で、且つ外装ケースの溶着シール部分の少なくともその一部とオーバーラップした位置に配設されるように構成することにより、薄いパックケース内に無駄なスペースが発生せず、電池パックの小型薄型化を可能とする。
【００２２】
【発明の実施の形態】
以下、添付図面を参照して本発明の一実施形態について説明し、本発明の理解に供する。尚、以下に示す実施形態は本発明を具体化した一例であって、本発明の技術的範囲を限定するものではない。
【００２３】
本実施形態に係る電池パックは、携帯電話機の電池電源として構成した例を示すものである。
【００２４】
図１は、実施形態に係る電池パックの構成を分解して示すもので、電池パック１は、上ケース２ａと下ケース２ｂとからなるパックケース２内にリチウムポリマー二次電池として構成された電池３、この電池３を保護する保護回路を構成したセーフティユニット（以下、ＳＵ）４及び臨界温度抵抗素子であるＰＴＣ５を備えて構成された電池保護装置８を収容し、電池パック１を携帯電話機に電気接続するための外部出力端子６ａ、６ｂ、６ｃを備えて構成されている。
【００２５】
この電池パック１は、携帯電話機に着脱自在に装填できるように構成されており、パックケース２を構成する上ケース２ａは携帯電話機の外装ケースの一部を構成する。従って、上ケース２ａは機器外装としての強度と美観を呈するように形成される。この上ケース２ａ及び下ケース２ｂは樹脂成形により形成され、電池３及び電池保護装置８を収容して両ケース間は超音波接合により一体化される。
【００２６】
前記電池３は、図２にその概略構造を示すように、シート状に形成された正極板と負極板とをポリマー電解質シートを介して複数層に積層して形成された発電要素１０を、ラミネートシートからなる柔軟な外装ケース１１内に収容して構成されている。この外装ケース１１は短冊状に切断されたラミネートシートを二つ折りにして、両サイドの斜線部を溶着シールして袋状に形成し、この中に発電要素１０を収容し、発電要素１０を構成する正極板から正極リード１２、負極板から負極リード１３を引き出し、リード引き出し辺１１ｂを溶着シールし、外装ケース１１内を密閉して形成される。両サイドのシール辺１１ａは、図１に示すように上面側に折り返して無駄な平面スペースの増加を減少させている。このように構成された電池３は、従来のリチウムイオン二次電池等のように正負極板を巻回構造にした構造に比して薄型の平板状に構成することができ、電池パック１としても薄く形成できるので、機器の薄型化に寄与できるものとなる。
【００２７】
また、前記電池保護装置８は、充放電を制御して過放電や過充電から電池３を保護する保護回路を回路基板１４上に構成したＳＵ４及び短絡等による過大な放電電流から電池３を保護するためのＰＴＣ素子５を備えて構成され、図示するように組み立てられた状態で供給される。この電池保護装置８は、図３に示すように、下ケース２ｂの所定位置に回路基板１４及びＰＴＣ素子５の板面方向を電池３の平板面と平行にして装着される。この電池保護装置８が下ケース２ｂに装着された後、図４に示すように、電池３を下ケース２ｂ内に収容して、電池３から引き出された正極リード１２及び負極リード１３と電池保護装置８側の正極接続リード３０及び負極接続リード３３とを接続した後、上ケース２ａを下ケース２ｂに接合して電池パック１が完成される。
【００２８】
上記電池保護装置８、電池３及び外部出力端子６ａ〜６ｃを下ケース２ｂ内に配設する手順は、以下に説明するように実施される。
【００２９】
図１に示すように、下ケース２ｂの側面から裏面側にかけた９０度方向に、端子装着部１９ａ、１９ｂ、１９ｃがそれぞれ凹部として形成されており、この凹部の底面には、図５に示すように、上下２か所にスリット状の端子挿入孔２２が下ケース２ｂ内に貫通するように形成されている。この端子挿入孔２２に、図１に示すように、コの字状に形成された各外部出力端子６ａ、６ｂ、６ｃを、それぞれの両先端部から圧入する。正極端子となる外部出力端子６ａは、その先端部の一方が特に長く形成されているので、下ケース２ｂに装着されたとき、下ケース２ｂに形成された接合穴２３の上に挿入先端が位置し、接合穴２３から挿入先端が覗くようになる。この接合穴２３上の挿入先端に図１に示す正極接続リード（正極接続部材）３０の端部を重ね合わせ、スポット溶接により両者を接合する。図６は、外部出力端子６ａの装着状態を示す断面図で、外部出力端子６ａの挿入先端の上に正極接続リード３０の端部が載置され、上下矢印で示すように溶接電極の一方を前記接合穴２３から挿入して外部出力端子６ａの挿入先端に当て、他方を前記正極接続リード３０に当ててスポット溶接がなされ、両者は接合される。
【００３０】
外部出力端子６ａ〜６ｃは、上下の端子挿入孔２２、２２から圧入されて下ケース２ｂに嵌合すると共に、下ケース２ｂ内に配設される各構成要素に接合されるので確実な取付け構造となる。また、図６に示すように、端子装着部１９ａ〜１９ｃの底面に密着した状態に装着されるので、電池パック１を携帯電話機に装填したときに電気的接続のために圧接される接続プローブ４４からの加圧を受けても確実な接続状態が得られ、接触抵抗の少ない電気的接続がなされる。
【００３１】
次に、図３に示すように、電池保護装置８に設けられたテスト端子２４ａ、２４ｂを下ケース２ｂに形成されたテスト端子窓２９ａ、２９ｂに嵌入することにより位置決めして、電池保護装置８を下ケース２ｂの端部に配設する。図７は、前記テスト端子２４ｂの配設状態を示す断面図で、テスト端子２４ｂの先端をコの字状に折り曲げた部分をテスト端子窓２９ｂの一辺に嵌入して位置決めすると同時に先端を下ケース２ｂに固定している。このテスト端子２４ａ、２４ｂの先端は、テスト端子窓２９ａ、２９ｂを通して外部から覗く位置にあるので、電池パック１完成後の製造検査時に検査プローブ４３を当接させて電気的な検査の用に供される。テスト端子２４ｂの基部はＰＴＣ素子５との接続部を形成し、更に直角方向に延長形成された負極接続リード（負極接続部材）３３は、電池３の負極リード１３との接合部位を形成する。
【００３２】
電池保護装置８が下ケース２ｂに位置決めされると、図８に示すように、ＳＵ４を構成した回路基板１４は、下ケース２ｂに装着された各外部出力端子６ａ、６ｂ、６ｃの下に配置され、回路基板１４に形成されたハンダ付けランド３１ａ、３１ｂ、３１ｃ上にそれぞれ外部出力端子６ａ、６ｂ、６ｃの先端部が当接した状態になる。この各ハンダ付けランド３１ａ、３１ｂ、３１ｃにそれぞれ外部出力端子６ａ、６ｂ、６ｃをハンダ付けすることにより端子接続がなされると同時に、外部出力端子６ａ〜６ｃ及び電池保護装置８が下ケース２ｂ上に位置固定される。
【００３３】
図８（ｂ）に示すように、回路基板１４及びＰＴＣ素子５の板面は、下ケース２ｂの底面と平行に配設されているので、電池保護装置８を収容した部分の厚さ方向のスペースを減少させることができる。更に、図４に示すように、電池３のリード引き出し辺１１ｂを電池保護装置８上に収容する厚さ方向のスペースをつくることができ、パックケース２内に無駄なスペースをつくることなく電池パック１の小型化を向上させている。また、リード引き出し辺１１ｂが電池保護装置８の上面を覆うことにより、電池３から引き出された正極リード１２、負極リード１３が電池保護装置８に接触することを防止している。この電池保護装置８を配設した状態では、電池保護装置８に設けられている負極接続リード３３及び正極接続リード３０は下ケース２ｂの端部に直立した状態に配置される。外部出力端子６ａ〜６ｃがハンダ付けされた回路基板１４のハンダ付け面は絶縁素材により被覆するオーバーコート処理がなされ、電気的絶縁を確保すると共に、電池３から電解液が漏出したような場合に液絡や腐食が生じることを防止する。
【００３４】
次に、図４に示すように、電池３をそのリード引き出し辺１１ｂを電池保護装置８側に向けて下ケース２ｂ内に収容する。電池３は、そのリード引き出し辺１１ｂが電池保護装置８上を覆うように配置され、下ケース２ｂに形成された凹部３２と位置決め凸部３４との間で収容位置が位置決めされる。この電池３のリード引き出し辺１１ｂから引き出された正極リード１２は正極接続リード３０に、負極リード１３は負極接続リード３３にそれぞれ対面するようになる。この正極リード１２と正極接続リード３０との間、負極リード１３と負極接続リード３３との間は、スポット溶接または超音波溶接により接合される。
【００３５】
図９は、正極リード１２と正極接続リード３０との間の接合を示すもので、正極リード１２は厚さ８０μｍのアルミニウムで形成されているため、接合が確実になされるようにするため、正極接続リード３０はアルミニウムとリン青銅とを圧延接合したクラッド材により形成されている。前記外部出力端子６ａ〜６ｃは外部接続の接続性を考慮してリン青銅で形成されており、これに接合される正極接続リード３０はリン青銅の面で外部出力端子６ａと当接させてスポット溶接される。一方、正極リード１２とはクラッド材のアルミニウムの面で対面させているので、正極リード１２と正極接続リード３０との間の接合はアルミニウム間の同種金属間の溶接となり、安定した接合がなされる。また、正極接続リード３０を銅系金属とし、正極リード１２と超音波溶接しても良好な接合が得られる。尚、負極リード１３は厚さ８０μｍの銅で形成されているので、リン青銅との接合性に問題はなく、従って負極接続リード３３はリン青銅で形成してスポット溶接または超音波溶接により確実に接合することができる。
【００３６】
図９（ａ）に示すように、正極リード１２と正極接続リード３０とが接合された後、図９（ｂ）に示すように、電池３のリード引き出し辺１１ｂ上に折り曲げられる。負極リード１３と負極接続リード３３との接合部位についても同様に折り曲げられる。この折り曲げられた部分と電池保護装置８との間にはリード引き出し辺１１ｂがあるので、正極リード１２及び負極リード１３が電池保護装置８に接触して異常を生じさせることはない。また、回路基板１４のハンダ付け面は前述したようにオーバーコートが施されているので、絶縁性はより確実に確保される。
【００３７】
このように電池３は、その一方の同一辺から正極リード１２及び負極リード１３が引き出され、このリード引き出し辺側に電池保護装置８が配設されるので、電池３と電池保護装置８との間の接続のために従来構成のようなリードの引回しがなく、外部出力端子６ａ〜６ｃ及び電池保護装置８は下ケース２ｂの所定位置に固定されるので、パックケース２内に収容される各構成要素間の接続が堅牢且つ確実になされ、電池パック１として携帯機器に用いるための薄型化に加えて堅牢性を備えたものとなる。
【００３８】
以上説明した工程により下ケース２ｂ内に各構成要素が収容された後、下ケース２ｂに上ケース２ａが超音波溶着により接合され、図１０に示すように、薄型形状の電池パック１に組み立てられる。この組み立て後にテスト端子窓２９ａ、２９ｂに検査用プローブを挿入してテスト端子２４ａ、２４ｂにコンタクトし、電池保護装置８が正常に動作するか否かの検査が実施される。検査合格となった電池パック１のテスト端子窓２９ａ、２９ｂ、接合窓２３等が設けられた凹部３５には目隠しシートが貼着され、各開口部分は閉じられる。
【００３９】
図１０（ａ）は電池パック１を下ケース２ｂ側から見た平面図で、電池３の平板面に対面する面は薄肉形成されて、電池３が膨張によりその厚さが変化した場合に弾性的に変形する弾性変形面１５が形成されている。また、この弾性変形面１５を取り囲むように突出形成された外周部１６が形成されている。更に、弾性変形面１５は薄肉形成されているので、刃物等による突き刺しにより電池３が損傷を受けることを防止するため、弾性変形面１５の周辺部分を除いた部分にステンレス薄板（金属薄板）７が貼着されている。このステンレス薄板７の角部には、外周部１６に当接する突出部７ａが形成され、ステンレス薄板７を弾性変形面１５に貼着するときの位置決めができるように構成されている。
【００４０】
尚、このステンレス薄板７は弾性変形面１５の全面に貼着してもよく、ステンレス薄板７の厚さを突き刺しに対する強度が得られる最低厚にすれば、変形量が大きくなる弾性変形面１５の周辺部においても弾性変形面１５の変形に追従して変形するので、弾性変形面１５の弾性変形を阻害することはない。
【００４１】
図１１は、図１０（ａ）のＡ−Ａ線矢視断面を示し、前記弾性変形面１５は本構成においては厚さ０．２２ｍｍに薄肉形成され、この弾性変形面１５の周囲には、所定高さに外周部１６が形成されている。この外周部１６の頂部と弾性変形面１５に貼着されたステンレス薄板７の表面との間には段差Ｈができるように外周部１６の突出高さが形成される。尚、本構成での段差Ｈは０．４ｍｍに設定されている。
【００４２】
電池３は、充放電の繰り返しや経年変化により電極板が膨張して電池３の厚さが増加する。電池３の膨張によりその厚さが増加して上ケース２ａと下ケース２ｂとの間の電池収容空間の高さを越えたとき、電池３の膨張による圧力は薄肉形成されて変形しやすくなっている弾性変形面１５を押し出して弾性変形させる。
【００４３】
極板を積層構造にした電池３の極板の膨張は電池３全体の厚さ変化として生じるので、弾性変形面１５は電池３と接触する面が平均的に押し上げられ、変形は図１１（ｂ）に示すように、外周部１６に接する周辺部で弾性変形する。本構成におけるリチウムポリマー二次電池の厚さは３．９１ｍｍで、これが充放電を繰り返した全寿命経過における膨張による厚さは４．３１ｍｍとなり、０．４ｍｍの膨張が生じるデータが取得されている。前述したように、弾性変形面１５上には外周部１６に囲まれた高さ０．４ｍｍの段差Ｈによる空間が形成されているため、電池パック１の全寿命が経過した状態でも電池パック１の最大厚さに変化は生じない。また、弾性変形面１５の表面には、その周囲を残してステンレス薄板７が貼着されていることにより、電池３の平均的な厚さ変化と相まって周囲の弾性変形により平面状態を保って均等に外周部１６内に膨出する。従って、電池の膨張で円弧状の膨らみが生じて電池パックとしての形状に違和感を与えたり、円弧状の膨らみにより機器に悪影響を与えることはない。
【００４４】
上記構成になる電池パック１は、図１２に断面図として示すように、携帯電話機９に装填される。先に図１４に示した従来構成になる電池パックに比して薄型化されているため携帯電話機９自体も薄型化され、ポケットに挿入できるまでのスリムな形態の携帯電話機９が実現される。携帯電話機９内の電池パック１が装填される反対面（表面側）には、プッシュキー１７、このプッシュキー１７による接点回路が形成された多層回路基板１８、この多層回路基板１８を支持する支持板１９が配設され、この支持板１９と電池パック１との間は、外周部１６との間に約０．０５ｍｍの間隙、弾性変形面１５上に貼着されたステンレス薄板７との間に約０．４５ｍｍの間隙が設けられている。
【００４５】
この構成によって、携帯電話機９の表面側から強い押圧が加わったときには外周部１６が支持板１９の変形を支える作用をなす。また、電池３は充放電あるいは経年変化により極板の膨張が生じて電池の厚さが増加するが、弾性変形面１５は電池３の膨張に対応して弾性変形し、前述したように外周部１６で囲まれた中に形成された空間で膨張による厚さ変化が収まり、膨張の影響を機器側に及ぼすことがない。
【００４６】
上記構成において、パックケース２内の電池３の収容空間の厚さ方向の寸法は、電池３の厚さ寸法誤差を考慮して電池３の厚さよりやや大きな寸法にすることを基本構成とするが、弾性変形面１５が弾性変形するように構成されているので、パックケース２内の電池３の収容空間の厚さ方向の寸法を、電池３の厚さ寸法より小さく形成することもできる。このように形成されたパックケース２内に電池３を収容することによって、電池３は弾性変形面１５により常時両面から圧縮方向に加圧を受けていることになり、電極板の膨張が抑制される効果が得られる。
【００４７】
また、電池３が膨張しない状態においては、弾性変形面１５、２５から圧縮方向に加圧を受けない状態の厚さ寸法に形成しておき、電池３が膨張したとき弾性変形面１５、２５を押し出そうとする力により圧縮方向の加圧を受けるようにしても電極板の膨張を抑制する効果が得られる。
【００４８】
また、電池３の膨張により弾性変形面１５が弾性変形するとき、最も変形量が大きくなる周辺部の厚さを他の部位の厚さより薄く形成すると周辺部の弾性変形が容易となり、電池３の膨張に対する追従性を向上させることができる。逆に、周辺部の厚さを他の部位の厚さより厚く形成すると変形し難くなるので、電池３の膨張に抗して電池３に圧縮力を加え、電池３の極板が膨張するのを抑制する加圧することになり、電池３の膨張を抑えることができる。
【００４９】
以上説明した電池パック１の構成は、携帯電話機の電池電源として適用した例について述べたが、モバイルコンピュータや電子手帳、トランシーバ等においても同様の構成を適用することができる。
【００５０】
また、本発明の構成では、電池保護装置８上に電池３のリード引き出し辺１１ｂが配設されるので、これらの間に絶縁部材、例えば樹脂シートを配置すると好適である。外装ケース１１を形成するラミネートシートは、アルミニウム層の両面に複数層に樹脂層が形成されており、振動や衝撃が加わったときに電池保護装置の金属部分と接触したとき、樹脂層が破壊されて金属層に触れると短絡が生じる恐れがある。前述のように絶縁部材を配置すると、リード引き出し辺１１ｂと電池保護装置との接触が防止される。また、リード引き出し辺１１ｂの両面に絶縁性のシートを配置すると、正極リード１２と正極接続リード３０及び負極リード１３と負極接続リード３３それぞれの接合部位とリード引き出し辺１１ｂとの接触も防止することができる。
【００５１】
また、以上の説明において、電池３は、その発電要素１０を複数の正負極板を積層した積層構造に構成した場合について述べ、極板を巻回した巻回構造のものでは、薄型の極板が得がたく、また極板が膨張したとき、その厚さが平均的に変化せず、弾性変形面１５が弧状に膨らむので、巻回構造の極板では弾性変形面１５の効果は得られないものとして説明した。しかし、その後の研究によって巻回構造のものであっても極板を平板状に圧縮形成したものにあっては、経年変化により極板が膨張したとき、積層構造の場合と同様に厚さが平均的に増加することが確かめられた。これは極板の厚さ方向では積層構造と同じ積層状態にあり、膨張したときに積層構造と同様に平均的な厚さ変化を呈するものと考えられる。従って、発電要素は積層構造、巻回構造のいずれの極板構成であっても説明した作用効果が得られることになる。
【００５２】
【発明の効果】
以上の説明の通り本発明によれば、発電要素をラミネートシートのような軟質の外装ケースに収容して平板状に形成された電池をパックケースに収容して構成しているので、電池パックの薄型化が可能となり、機器の薄型化に貢献できるものとなる。また、電池の正負それぞれのリードが同一辺側から引き出されるので、このリード引き出し辺側に電池保護装置及び外部出力端子を配設することにより、パックケース内のリードの引回しが簡略化され、電気絶縁等が確実になされ不良発生の少ない電池パックを構成することができる。また、電池保護装置を構成するＳＵを形成した回路基板及びＰＴＣ素子は、その板面方向を電池の平板面と平行に配設されるので、電池の厚さを収容だけの薄いパックケースへの収容を可能とし、更に、電池保護装置上に前記リード引き出し辺を収容して電池パックの小型化にも寄与するものとなる。
【図面の簡単な説明】
【図１】実施形態に係る電池パックの構成を示す分解斜視図。
【図２】電池の概略構成を示す平面図。
【図３】下ケースに電池保護装置を配設した状態を示す斜視図。
【図４】下ケースに電池保護装置及び電池を配設した状態を示す斜視図。
【図５】端子装着部の構成を示す下ケースの側面図。
【図６】外部出力端子の装着及び正極接続リードとの接合を説明する断面図。
【図７】テスト端子の装着構造を説明する断面図。
【図８】電池保護装置の配設状態を示す（ａ）は平面図、（ｂ）は側面図。
【図９】正極リードと正極接続リードとの接合（ａ）及びリードの格納状態（ｂ）を示す断面図。
【図１０】電池パックの完成状態を示す（ａ）は平面図、（ｂ）は側面図。
【図１１】弾性変形面の変形を説明する（ａ）は平常時、（ｂ）は電池膨張時のＡ−Ａ線矢視断面図。
【図１２】電池パックを携帯電話機に装填した状態を示す断面図。
【図１３】従来構成になる電池パックの（ａ）は内部配置、（ｂ）は電池の裏面側を示す平面図。
【図１４】従来構成になる電池パックの携帯電話機への装填状態を示す断面図。
【符号の説明】
１電池パック
２パックケース
２ａ上ケース
２ｂ下ケース
３電池
４保護回路（ＳＵ）
５ＰＴＣ素子
６ａ、６ｂ、６ｃ外部出力端子
１０発電要素
１１外装ケース
１１ｂ引き出し辺
１２正極リード
１３負極リード
１４回路基板
３０正極接続リード（正極接続部材）
３３負極接続リード（負極接続部材）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a battery pack used as a battery power source for portable information devices such as a mobile phone and a mobile computer.
[0002]
[Prior art]
FIG. 13A shows the internal configuration of a battery pack 49 accommodating portion of a mobile phone having a conventional configuration. A battery 51 formed of a lithium ion secondary battery is accommodated in a pack case 50 and this battery The battery protection device 52 includes a battery protection device 52 for protecting the battery 51 from overcharge, overdischarge, and the like. The battery 51 is configured such that a battery can 61 containing a power generation element is provided with a negative electrode terminal, and a sealing plate 62 sealing the battery can is provided with a positive electrode terminal. Accordingly, electrical connection is made between the negative electrode terminal and the positive electrode terminal and the battery protection device 52 by the positive electrode connection lead 53 and the negative electrode connection lead 54 as illustrated. Further, the positive electrode connection lead 53 and the negative electrode connection lead 54 have a function as a support member for holding the battery protection device 52 on the lithium ion secondary battery 51. One end of the positive electrode connection lead 53 is spot-welded to the positive electrode terminal of the lithium ion secondary battery 51, and an insulating paste is adhered on the battery can 61 to ensure insulation between the negative electrode terminal and the battery can 61. The other end is extended on the sheet 55 and soldered to a circuit board 56 on which a protection circuit is formed. One end of the negative electrode connection lead 54 is spot-welded to the bottom surface of the battery can 61, and the other end is soldered to the circuit board 56.
[0003]
The battery protection device 52 is provided to protect the battery 51 from overdischarge, overcharge, short circuit, or the like. The battery 51 is connected to the external output terminals 57a to 57d via the battery protection device 52. . The external output terminals 57 a to 57 d and the test terminals 58 of the terminal support plate 59 to which the external output terminals 57 a to 57 d and the test terminals 58 are attached are attached to the circuit board 56 on which a circuit for protecting the battery is formed. By soldering, the circuit board 56 and the terminal support plate 59 are integrated to form the battery protection device 52. FIG. 13B shows the configuration of the opposite surface of the battery 51 and the battery protection device 52. When the battery pack is mounted on the mobile phone, a connection probe provided on the mobile phone contacts the external output terminals 57a to 57d, so that the battery pack is electrically connected to the mobile phone. The test terminal 58 has an extended end disposed on an insulating sheet 60 for securing insulation from the battery can 61, and a test piece 62 having one end spot-welded to the battery can 61 through an opening hole provided in the pack case 50. The exposed portion is used for an operation test of the battery protection device 52. After the operation test, the opening is closed by the covering sheet.
[0004]
As shown in FIG. 13B, in the battery pack 49 having the conventional configuration, the battery 51, the battery protection device 52, and the external output terminals 57a to 57d are integrally formed as shown in FIG. The external output terminals 57a to 57d are configured to be exposed to the outside from the opening of the pack case 50 by being housed in the pack case 50 as shown in FIG.
[0005]
[Problems to be solved by the invention]
While the progress of miniaturization of mobile phones has been remarkable, the next development task is to reduce the thickness. This reduction in thickness has become an issue required not only for mobile phones but also for mobile information devices such as mobile computers and electronic organizers. The miniaturization alone cannot always satisfy the convenience of carrying, and the portability is improved only when the thickness is reduced, and the portable telephone enables the pocket-in carrying that can be inserted into the breast pocket without any discomfort.
[0006]
The battery pack 49 having the conventional configuration is mounted on the mobile phone 70 as shown in FIG. 14 as a cross section of the battery mounting position of the mobile phone. is occupying. The reduction in thickness of the battery pack 49 is an important factor for achieving a reduction in the thickness of the mobile phone 70. Other portable information devices are also in the same battery mounted state, and a thin battery is an indispensable element for realizing a small, lightweight and thin portable information device, in particular, a thin profile.
[0007]
However, in a battery in which the positive and negative electrodes are accommodated in a metal battery can, such as a lithium ion secondary battery used in the conventional battery pack 49, there is a limit to reducing the thickness of the battery can. Further, as shown in FIG. 13, connection between the positive electrode terminal and the negative electrode terminal of the battery and the battery protection device requires many members and processing steps, and components other than the battery also hinder the thinning of the battery pack. are doing. Furthermore, the arrangement structure of the battery protection device 52 requires a space in the thickness direction in the pack case 50, and there is a problem that the thickness of the support structure of the external output terminals 57a to 57d is further increased.
[0008]
An object of the present invention is to reduce the thickness by using a battery configured by housing the positive and negative electrodes in an outer case formed of a soft material, and to adjust other components to the thin shape of the battery. In order to realize a thin battery pack.
[0009]
[Means for Solving the Problems]
A first invention of the present application for achieving the above object is configured to include a secondary battery formed in a flat shape, a circuit board on which a protection circuit for protecting the secondary battery is formed, and a PTC element. The battery protection device is housed in a flat case formed by joining a lower case serving as a storage container and an upper case serving as a lid closing an opening side of the lower case, and the secondary battery is provided. In the battery pack formed by connecting the positive electrode lead and the negative electrode lead drawn out from the battery protection device to an external output terminal provided in the pack case, the secondary battery is formed by laminating sheet-like positive and negative electrode plates. The power generation element formed in this manner is housed in an outer case in which the periphery of a pair of laminated sheets is welded and sealed, and a positive electrode lead and a negative electrode lead are drawn out from one side of the welded seal. The battery protection device is characterized by comprising disposed on one side of the positive electrode lead and the negative electrode lead is drawn out.
[0010]
According to this configuration, in a secondary battery having a positive / negative electrode plate laminated structure, the positive electrode lead and the negative electrode lead can be pulled out from one side where the laminate sheet serving as the outer case is welded and sealed, and the battery protection side is provided on the lead drawing side. By arranging the device, the connection between the secondary battery and the battery protection device is made in the shortest distance, resulting in a simple structure, reducing the number of components and processing steps, and facilitating the thinning of the battery pack. .
[0011]
In the above configuration, the circuit board is disposed at a position where the plate surface direction is parallel to the uneven plane direction of the secondary battery and overlaps with at least a part of the welded seal portion of the outer case. The device can be accommodated in a thin pack case and a space for accommodating the welded seal portion can be provided, so that the battery pack can be reduced in size and thickness.
[0012]
Further, a battery protection device is disposed near the lower case in the pack case, and the positive electrode connection member and the negative electrode connection member connected to the circuit board, and the positive electrode lead and the negative electrode lead are respectively positioned closer to the upper case. And the battery sealing device is disposed between the lead connection position and the battery protection device, so that even when the lead connection position is provided on the battery protection device, the welding sealing portion is provided. Can be interposed therebetween to ensure insulation between the lead connection portion and the battery protection device.
[0013]
Further, the circuit board is formed such that one surface of the substrate is formed as a component mounting surface and the other surface is formed as a soldering surface, and the soldering surface is disposed facing the open surface side of the lower case. Connection to the soldering surface, insulation treatment, and the like can be easily performed.
[0014]
In addition, by configuring the soldering surface of the circuit board so as to be covered with an insulating material after completion of the connection processing, it is possible to prevent the occurrence of a liquid junction or corrosion on the circuit board when the electrolyte leaks from the battery. be able to.
[0015]
The PTC element is formed in a plate shape, and its plate surface direction is parallel to the direction of the uneven plane of the secondary battery, and is disposed at a position overlapping at least a part of the welded seal portion of the outer case. With such a configuration, the battery pack can be accommodated in a thin pack case and a space for accommodating the welded seal portion can be provided, so that the battery pack can be reduced in size and thickness.
[0016]
According to a second aspect of the present invention, there is provided a battery pack comprising a secondary battery formed in a flat plate shape and a circuit board provided with a circuit board having at least a protection circuit for protecting the secondary battery in a pack case. In the battery pack, the positive electrode lead and the negative electrode lead drawn from the secondary battery are connected to a positive external output terminal and a negative external output terminal provided in a pack case via the battery protection device. secondary battery, a power generating element housed in the outer case comprising a pair of laminate sheet, composed of welded seal portion of the welded sealed one side is drawn positive electrode lead and the negative electrode lead, the cathode external output terminal and a negative electrode external The output terminal is mounted and fixed on the side of the lead case side of the pack case, and the circuit board is positioned so that its plate surface direction is parallel to the plate surface direction of the secondary battery. The battery protection device is disposed between the secondary battery and the external output terminal so as to overlap at least a part of the welded seal portion of the outer case, and the battery protection device is shifted toward one side in the thickness direction in the pack case. The positive electrode connecting member and the negative electrode connecting member are connected to the circuit board, and the positive electrode lead and the negative electrode lead are connected at a position closer to the other side in the thickness direction in the pack case. The welded seal portion of the outer case is disposed between the external case and the positive external output terminal and the negative external output terminal are connected to a circuit board at respective extending portions .
[0017]
According to this configuration, pull the positive electrode plate and connected to positive electrode and negative electrode leads to the negative electrode plate constituting the power generating element laminated sheet as an exterior case from welded sealed one side, pack case side face of the lead drawer side By arranging the battery protection device between the external output terminal fixed and attached to the secondary battery and the secondary battery, the connection between the secondary battery, the battery protection device and the external output terminal is made in the shortest distance, and a simple The structure reduces the number of components and processing steps, and facilitates thinning of the battery pack.
[0018]
Further, since the circuit board is disposed at a position where its plate surface direction is parallel to the plate surface direction of the secondary battery and overlaps with at least a part of the welded seal portion of the outer case, the battery protection device is provided. The battery pack is accommodated in a thin pack case, and a space for accommodating the welding seal portion is provided, so that the battery pack can be reduced in size and thickness.
[0019]
Further, the battery protection device is disposed at one side in the thickness direction in the pack case, and the positive electrode connection member and the negative electrode connection member connected to the circuit board, and the positive electrode lead and the negative electrode lead are respectively arranged in the thickness direction in the pack case. of being connected with the position of the other closer, since the welding sealing portion of the secondary battery is configured to be disposed between the lead connection position and battery protection device, the lead connection position on the battery protection device Even if it is arranged, the welded seal portion is interposed therebetween to ensure insulation between the lead connection portion and the battery protection device.
[0020]
Further, by providing an insulating member between at least the welded seal portion of the outer case and the battery protection device, the welded seal portion of the outer case arranged to be overlapped on the battery protection device is formed on the circuit board. When a vibration or an impact is applied to the laminated sheet, the resin layer of the laminate sheet is broken and an accident that the conductive portion comes into contact with the metal layer is prevented.
[0021]
In addition, the battery protection device includes a PTC element, and the PTC element is formed in a plate shape, and its plate surface direction is parallel to the plate surface direction of the secondary battery, and at least a part of a welded seal portion of the outer case. With such a configuration that the battery pack is disposed at a position overlapping with the battery pack, useless space is not generated in the thin pack case, and the battery pack can be reduced in size and thickness.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.
[0023]
The battery pack according to the present embodiment is an example configured as a battery power source of a mobile phone.
[0024]
FIG. 1 is an exploded view of a configuration of a battery pack according to an embodiment. A battery pack 1 is configured as a lithium polymer secondary battery in a pack case 2 including an upper case 2a and a lower case 2b. 3. A battery protection device 8 including a safety unit (hereinafter referred to as SU) 4 having a protection circuit for protecting the battery 3 and a PTC 5 which is a critical temperature resistance element is accommodated, and the battery pack 1 is mounted on a mobile phone. It is provided with external output terminals 6a, 6b, 6c for electrical connection.
[0025]
The battery pack 1 is configured to be removably mountable in a mobile phone, and an upper case 2a forming the pack case 2 forms a part of an outer case of the mobile phone. Therefore, the upper case 2a is formed so as to exhibit the strength and aesthetic appearance as a device exterior. The upper case 2a and the lower case 2b are formed by resin molding, accommodate the battery 3 and the battery protection device 8, and are integrated by ultrasonic bonding between the two cases.
[0026]
As shown in FIG. 2, the battery 3 includes a power generating element 10 formed by laminating a sheet-like positive electrode plate and a negative electrode plate into a plurality of layers via a polymer electrolyte sheet. It is configured to be accommodated in a flexible outer case 11 made of a sheet. This outer case 11 is formed by folding a laminate sheet cut in a strip shape into two, forming a bag shape by welding and sealing hatched portions on both sides, and accommodating the power generation element 10 therein. The negative electrode lead 13 is drawn out of the positive electrode plate and the negative electrode lead 13 is drawn out of the negative electrode plate, and the lead drawing side 11b is welded and sealed, and the inside of the outer case 11 is sealed. As shown in FIG. 1, the seal sides 11a on both sides are folded back toward the upper surface to reduce an increase in useless flat space. The battery 3 configured as described above can be formed in a flat plate shape thinner than a structure in which the positive and negative electrodes are wound as in a conventional lithium ion secondary battery or the like. Can also be formed thinly, which can contribute to making the device thinner.
[0027]
Also, the battery protection device 8 protects the battery 3 from an excessive discharge current due to SU4 and a short circuit, etc., in which a protection circuit for controlling the charge and discharge to protect the battery 3 from overdischarge or overcharge is formed on the circuit board 14. The PTC element 5 is provided in a state assembled as shown in the figure. As shown in FIG. 3, the battery protection device 8 is mounted at a predetermined position of the lower case 2 b with the circuit board 14 and the PTC element 5 having the plate surface directions parallel to the plate surface of the battery 3. After the battery protection device 8 is mounted on the lower case 2b, as shown in FIG. 4, the battery 3 is housed in the lower case 2b, and the positive electrode lead 12 and the negative electrode lead 13 drawn from the battery 3 are connected to the battery protection device. After connecting the positive connection lead 30 and the negative connection lead 33 on the device 8 side , the upper case 2a is joined to the lower case 2b to complete the battery pack 1.
[0028]
The procedure for disposing the battery protection device 8, the battery 3, and the external output terminals 6a to 6c in the lower case 2b is performed as described below.
[0029]
As shown in FIG. 1, terminal mounting portions 19a, 19b, and 19c are formed as recesses in a 90-degree direction from the side surface to the back surface side of the lower case 2b, and the bottom surface of the recess is shown in FIG. As described above, the slit-shaped terminal insertion holes 22 are formed at two upper and lower locations so as to penetrate into the lower case 2b. As shown in FIG. 1, each of the U-shaped external output terminals 6a, 6b, and 6c is press-fitted into each of the terminal insertion holes 22 from both ends thereof. The external output terminal 6a serving as a positive electrode terminal has one end portion formed particularly long, so that when the external output terminal 6a is mounted on the lower case 2b, the insertion end position is above the joint hole 23 formed in the lower case 2b. Then, the insertion tip comes to look through the joint hole 23. The end of the positive electrode connecting lead (positive electrode connecting member) 30 shown in FIG. 1 is superimposed on the insertion tip on the joining hole 23, and the two are joined by spot welding. FIG. 6 is a cross-sectional view showing the mounted state of the external output terminal 6a. The end of the positive electrode connection lead 30 is placed on the insertion end of the external output terminal 6a, and one of the welding electrodes is connected as shown by the up and down arrows. Spot welding is performed by inserting the external output terminal 6a through the joint hole 23 and applying the other end to the positive electrode connecting lead 30, and joining the two.
[0030]
The external output terminals 6a to 6c are press-fitted from the upper and lower terminal insertion holes 22 and 22 to fit into the lower case 2b and are joined to the respective components arranged in the lower case 2b, so that a secure mounting structure is provided. It becomes. Further, as shown in FIG. 6, since the battery pack 1 is mounted in close contact with the bottom surfaces of the terminal mounting portions 19a to 19c, the connection probe 44 pressed for electrical connection when the battery pack 1 is mounted on the mobile phone. Thus, a reliable connection state can be obtained even when pressure is applied, and an electrical connection with low contact resistance is made.
[0031]
Next, as shown in FIG. 3, the test terminals 24a and 24b provided on the battery protection device 8 are positioned by fitting them into test terminal windows 29a and 29b formed on the lower case 2b. At the end of the lower case 2b. FIG. 7 is a cross-sectional view showing the arrangement of the test terminals 24b. The portion of the test terminal 24b whose upper end is bent in a U-shape is inserted into one side of the test terminal window 29b for positioning, and at the same time, the lower end is placed in the lower case. 2b. Since the tips of the test terminals 24a and 24b are at positions where the test terminals 24a and 29b are viewed from the outside through the test terminal windows 29a and 29b, the inspection probe 43 is brought into contact with the battery during the production inspection after the completion of the battery pack 1 and used for electrical inspection. Is done. The base of the test terminal 24b forms a connection portion with the PTC element 5, and the negative electrode connection lead (negative electrode connection member) 33 formed to extend in the perpendicular direction forms a joint portion with the negative electrode lead 13 of the battery 3.
[0032]
When the battery protection device 8 is positioned on the lower case 2b, as shown in FIG. 8, the circuit board 14 constituting the SU4 is arranged below the external output terminals 6a, 6b, 6c mounted on the lower case 2b. Then, the ends of the external output terminals 6a, 6b, 6c are in contact with the solder lands 31a, 31b, 31c formed on the circuit board 14, respectively. The external output terminals 6a, 6b, and 6c are soldered to the soldering lands 31a, 31b, and 31c, respectively, so that the terminals are connected, and at the same time, the external output terminals 6a to 6c and the battery protection device 8 are placed on the lower case 2b. The position is fixed.
[0033]
As shown in FIG. 8B, since the plate surfaces of the circuit board 14 and the PTC element 5 are arranged in parallel with the bottom surface of the lower case 2b, the thickness of the portion housing the battery protection device 8 in the thickness direction is reduced. Space can be reduced. Further, as shown in FIG. 4, a space in the thickness direction for accommodating the lead lead-out side 11 b of the battery 3 on the battery protection device 8 can be created, and the battery pack can be made without wasting space in the pack case 2. 1 is improved. In addition, the lead lead side 11b covers the upper surface of the battery protection device 8, thereby preventing the positive electrode lead 12 and the negative electrode lead 13 drawn from the battery 3 from coming into contact with the battery protection device 8. In a state where the battery protection device 8 is provided, the negative electrode connection lead 33 and the positive electrode connection lead 30 provided on the battery protection device 8 are disposed upright at the end of the lower case 2b. The soldering surface of the circuit board 14 to which the external output terminals 6a to 6c are soldered is subjected to an overcoating process of covering with an insulating material, to secure electrical insulation and to prevent the electrolyte from leaking from the battery 3. Prevents liquid junctions and corrosion.
[0034]
Next, as shown in FIG. 4, the battery 3 is accommodated in the lower case 2b with the lead lead-out side 11b facing the battery protection device 8 side. The battery 3 is disposed such that the lead extraction side 11b covers the battery protection device 8, and the accommodation position is determined between the concave portion 32 and the positioning convex portion 34 formed in the lower case 2b. The positive electrode lead 12 and the negative electrode lead 13 pulled out from the lead extraction side 11b of the battery 3 face the positive electrode connection lead 30, respectively. The positive electrode lead 12 and the positive electrode connection lead 30 and the negative electrode lead 13 and the negative electrode connection lead 33 are joined by spot welding or ultrasonic welding.
[0035]
FIG. 9 shows the bonding between the positive electrode lead 12 and the positive electrode connecting lead 30. Since the positive electrode lead 12 is formed of aluminum having a thickness of 80 μm, the positive electrode lead 12 is formed so that the bonding can be reliably performed. The connection lead 30 is formed of a clad material formed by rolling and joining aluminum and phosphor bronze. The external output terminals 6a to 6c are formed of phosphor bronze in consideration of the connectivity of the external connection, and the positive electrode connection lead 30 joined thereto is spotted by contacting the external output terminal 6a with the phosphor bronze surface. Welded. On the other hand, since the positive electrode lead 12 faces the aluminum surface of the clad material, the bonding between the positive electrode lead 12 and the positive electrode connection lead 30 is welding between the same metals between aluminum, and stable bonding is performed. . Further, even if the positive electrode connecting lead 30 is made of a copper-based metal and the positive electrode lead 12 is ultrasonically welded, good joining is obtained. Incidentally, since the negative electrode lead 13 is formed of copper having a thickness of 80 μm, there is no problem in the bonding property with phosphor bronze. Therefore, the negative electrode connection lead 33 is formed of phosphor bronze and reliably formed by spot welding or ultrasonic welding. Can be joined.
[0036]
After the positive electrode lead 12 and the positive electrode connecting lead 30 are joined as shown in FIG. 9A, the battery 3 is bent over the lead extraction side 11b of the battery 3 as shown in FIG. 9B. The joint between the negative electrode lead 13 and the negative electrode connection lead 33 is similarly bent. Since there is a lead lead side 11b between the bent portion and the battery protection device 8, the positive electrode lead 12 and the negative electrode lead 13 do not contact the battery protection device 8 to cause an abnormality. Further, since the soldering surface of the circuit board 14 is overcoated as described above, the insulation is more reliably ensured.
[0037]
As described above, in the battery 3, the positive electrode lead 12 and the negative electrode lead 13 are drawn out from one of the same sides, and the battery protection device 8 is provided on the side from which the lead is drawn. The external output terminals 6a to 6c and the battery protection device 8 are fixed to predetermined positions of the lower case 2b because there is no lead routing unlike the conventional configuration because of the connection between them. The connection between the components is made robust and reliable, and the battery pack 1 has a robustness in addition to a reduction in thickness for use in a portable device.
[0038]
After each component is accommodated in the lower case 2b by the process described above, the upper case 2a is joined to the lower case 2b by ultrasonic welding, and as shown in FIG. 10, assembled into a thin battery pack 1. . After this assembly, an inspection probe is inserted into the test terminal windows 29a and 29b to make contact with the test terminals 24a and 24b, and an inspection is performed to determine whether the battery protection device 8 operates normally. A blind sheet is adhered to the concave portion 35 of the battery pack 1 that has passed the inspection, in which the test terminal windows 29a and 29b, the joining window 23, and the like are provided, and each opening is closed.
[0039]
FIG. 10A is a plan view of the battery pack 1 as viewed from the lower case 2b side. The surface of the battery 3 facing the flat surface is formed to be thin, and when the thickness of the battery 3 changes due to expansion, the elasticity is increased. An elastically deformable surface 15 is formed to be deformed. An outer peripheral portion 16 is formed so as to protrude so as to surround the elastic deformation surface 15. Further, since the elastically deformable surface 15 is formed to be thin, the stainless steel plate (metallic thin plate) 7 is provided on a portion other than the peripheral portion of the elastically deformable surface 15 in order to prevent the battery 3 from being damaged by piercing with a blade or the like. Is affixed. A protruding portion 7 a is formed at a corner of the stainless steel plate 7 to be in contact with the outer peripheral portion 16, so that the stainless steel plate 7 can be positioned when it is attached to the elastically deformable surface 15.
[0040]
The stainless steel plate 7 may be adhered to the entire surface of the elastically deformable surface 15. If the thickness of the stainless steel plate 7 is set to the minimum thickness at which the strength against piercing is obtained, the deformation amount of the elastically deformable surface 15 becomes large. Since the peripheral portion also deforms following the deformation of the elastic deformation surface 15, the elastic deformation of the elastic deformation surface 15 is not hindered.
[0041]
FIG. 11 is a cross-sectional view taken along line AA of FIG. 10 (a). In the present configuration, the elastic deformation surface 15 is formed to be thin with a thickness of 0.22 mm. An outer peripheral portion 16 is formed at a predetermined height. A protruding height of the outer peripheral portion 16 is formed between the top of the outer peripheral portion 16 and the surface of the stainless steel plate 7 adhered to the elastic deformation surface 15 so that a step H is formed. In this configuration, the step H is set to 0.4 mm.
[0042]
In the battery 3, the electrode plate expands due to repeated charge / discharge or aging, and the thickness of the battery 3 increases. When the thickness of the battery 3 increases due to the expansion of the battery 3 and exceeds the height of the battery housing space between the upper case 2a and the lower case 2b, the pressure due to the expansion of the battery 3 is thinned and easily deformed. The elastic deformation surface 15 is pushed out and elastically deformed.
[0043]
Since the expansion of the electrode plate of the battery 3 having the electrode plate laminated structure occurs as a change in the thickness of the entire battery 3, the surface of the elastic deformation surface 15 that contacts the battery 3 is pushed up on average, and the deformation is shown in FIG. As shown in (), elastic deformation occurs at the peripheral portion that contacts the outer peripheral portion 16. The thickness of the lithium polymer secondary battery in this configuration is 3.91 mm, and the thickness due to expansion over the entire lifetime after repeated charge / discharge is 4.31 mm, and data that causes expansion of 0.4 mm has been acquired. . As described above, since the space formed by the step H having a height of 0.4 mm and surrounded by the outer peripheral portion 16 is formed on the elastic deformation surface 15, the battery pack 1 can be maintained even after the entire life of the battery pack 1 has elapsed. No change occurs in the maximum thickness. Further, since the stainless steel plate 7 is adhered to the surface of the elastic deformation surface 15 except for the periphery thereof, the flat state is maintained by the elastic deformation of the surroundings and the flat state is maintained in combination with the average thickness change of the battery 3. Bulges into the outer peripheral portion 16. Therefore, an arc-shaped bulge does not occur due to the expansion of the battery, giving a sense of incongruity to the shape of the battery pack, and does not adversely affect the device due to the arc-shaped bulge.
[0044]
The battery pack 1 having the above configuration is mounted on a mobile phone 9 as shown in a sectional view in FIG. Since the mobile phone 9 is thinner than the battery pack having the conventional configuration shown in FIG. 14, the mobile phone 9 itself is also thinned, and the mobile phone 9 is slim enough to be inserted into a pocket. On the opposite side (front side) of the mobile phone 9 on which the battery pack 1 is loaded, a push key 17, a multilayer circuit board 18 having a contact circuit formed by the push key 17, and a support for supporting the multilayer circuit board 18 A plate 19 is provided, a gap between the support plate 19 and the battery pack 1 is about 0.05 mm between the support plate 19 and the outer peripheral portion 16, and a gap between the support plate 19 and the stainless steel plate 7 adhered on the elastic deformation surface 15. Is provided with a gap of about 0.45 mm.
[0045]
With this configuration, when strong pressing is applied from the front side of the mobile phone 9, the outer peripheral portion 16 functions to support the deformation of the support plate 19. Further, the battery 3 increases in thickness due to expansion of the electrode plate due to charge / discharge or aging, but the elastically deformable surface 15 is elastically deformed in accordance with the expansion of the battery 3, and the outer peripheral portion as described above The change in thickness due to expansion is suppressed in the space formed inside surrounded by 16, and the influence of expansion is not exerted on the device side.
[0046]
In the above configuration, the basic configuration is such that the dimension of the accommodation space of the battery 3 in the pack case 2 in the thickness direction is slightly larger than the thickness of the battery 3 in consideration of the thickness dimension error of the battery 3. Since the elastically deformable surface 15 is configured to be elastically deformed, the size of the accommodation space for the battery 3 in the pack case 2 in the thickness direction can be made smaller than the thickness of the battery 3. By housing the battery 3 in the pack case 2 formed in this way, the battery 3 is always under pressure from both sides in the compression direction by the elastically deformable surface 15, and the expansion of the electrode plate is suppressed. Effect can be obtained.
[0047]
When the battery 3 does not expand, the elastic deformation surfaces 15 and 25 are formed to have a thickness that does not receive pressure in the compression direction, and when the battery 3 expands, the elastic deformation surfaces 15 and 25 are formed. The effect of suppressing the expansion of the electrode plate can be obtained even when pressure is applied in the compression direction by the pushing force.
[0048]
Further, when the elastic deformation surface 15 is elastically deformed by the expansion of the battery 3, if the thickness of the peripheral portion where the amount of deformation is largest is made smaller than the thickness of the other portions, the elastic deformation of the peripheral portion becomes easy and the battery 3 Followability to expansion can be improved. Conversely, if the peripheral portion is formed to be thicker than the other portions, it is difficult to deform. Therefore, a compressive force is applied to the battery 3 against the expansion of the battery 3 to prevent the electrode plate of the battery 3 from expanding. Pressurization is suppressed, and expansion of the battery 3 can be suppressed.
[0049]
Although the configuration of the battery pack 1 described above has been described as an example in which the configuration is applied to a battery power source of a mobile phone, the same configuration can be applied to a mobile computer, an electronic organizer, a transceiver, and the like.
[0050]
In the configuration of the present invention, since the lead lead-out side 11b of the battery 3 is provided on the battery protection device 8, it is preferable to arrange an insulating member, for example, a resin sheet between them. The laminate sheet forming the outer case 11 has a plurality of resin layers formed on both surfaces of the aluminum layer, and when the metal sheet of the battery protection device comes into contact with the battery when vibration or impact is applied, the resin layer is broken. Touching the metal layer may cause a short circuit. When the insulating member is arranged as described above, contact between the lead lead-out side 11b and the battery protection device is prevented. When insulating sheets are arranged on both sides of the lead lead-out side 11b, the contact between the joint portions of the positive electrode lead 12, the positive electrode connection lead 30, and the negative electrode lead 13 and the negative electrode connection lead 33 with the lead lead-out side 11b is also prevented. Can be.
[0051]
In the above description, the battery 3 has a case where the power generating element 10 has a stacked structure in which a plurality of positive and negative electrode plates are stacked. When the electrode plate expands, its thickness does not change on average and the elastic deformation surface 15 expands in an arc shape, so that the effect of the elastic deformation surface 15 can be obtained with the wound electrode plate. Described as none. However, in later studies, even in the case of a wound structure, even if the electrode plate was compressed and formed into a flat plate shape, when the electrode plate expanded due to aging, the thickness was the same as in the case of the laminated structure. It was confirmed that it increased on average. This is considered to be in the same lamination state as the laminated structure in the thickness direction of the electrode plate, and exhibit an average thickness change when expanded, like the laminated structure. Therefore, the above-described operation and effect can be obtained regardless of whether the power generation element has a laminated structure or a wound structure.
[0052]
【The invention's effect】
As described above, according to the present invention, the power generation element is housed in a soft outer case such as a laminate sheet, and the battery formed in a flat shape is housed in the pack case. The device can be made thinner, which contributes to making the device thinner. Also, since the positive and negative leads of the battery are pulled out from the same side, by arranging the battery protection device and the external output terminal on the side from which the lead is drawn, the lead routing in the pack case is simplified, It is possible to form a battery pack in which electrical insulation and the like are reliably performed and the occurrence of defects is reduced. In addition, the circuit board and the PTC element on which the SU constituting the battery protection device is formed are arranged with their plate surface directions parallel to the flat plate surface of the battery. The battery pack can be accommodated, and the lead-out side is accommodated on the battery protection device, thereby contributing to downsizing of the battery pack.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a configuration of a battery pack according to an embodiment.
FIG. 2 is a plan view showing a schematic configuration of a battery.
FIG. 3 is a perspective view showing a state in which a battery protection device is provided in a lower case.
FIG. 4 is a perspective view showing a state in which a battery protection device and a battery are provided in a lower case.
FIG. 5 is a side view of a lower case showing a configuration of a terminal mounting portion.
FIG. 6 is a cross-sectional view for explaining attachment of an external output terminal and joining with a positive electrode connection lead.
FIG. 7 is a cross-sectional view illustrating a mounting structure of a test terminal.
8A is a plan view and FIG. 8B is a side view showing an arrangement state of the battery protection device.
FIGS. 9A and 9B are cross-sectional views illustrating a connection between a positive electrode lead and a positive electrode connection lead (a) and a stored state of the lead (b).
10A is a plan view and FIG. 10B is a side view showing a completed state of the battery pack.
FIGS. 11A and 11B are cross-sectional views taken along line AA of FIG. 11A for explaining the deformation of the elastically deformable surface when the battery is expanded, and FIG.
FIG. 12 is a cross-sectional view showing a state where a battery pack is mounted on a mobile phone.
FIGS. 13A and 13B are plan views showing a battery pack having a conventional configuration, in which FIG.
FIG. 14 is a cross-sectional view showing a state in which a battery pack having a conventional configuration is mounted on a mobile phone.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Battery pack 2 Pack case 2a Upper case 2b Lower case 3 Battery 4 Protection circuit (SU)
5 PTC element 6a, 6b, 6c External output terminal 10 Power generation element 11 Outer case 11b Drawer side 12 Positive lead 13 Negative lead 14 Circuit board 30 Positive connection lead (positive connection member)
33 Negative electrode connection lead (Negative electrode connection member)

Claims

A lower case serving as a storage container, including a secondary battery formed in a flat shape, a battery protection device configured with a circuit board and a PTC element on which a protection circuit for protecting the secondary battery is formed, The lower case is housed in a flat case formed by joining an upper case forming a lid that closes the opening side of the lower case, and the positive electrode lead and the negative electrode lead drawn from the secondary battery are connected to the battery protection device. A battery pack connected to an external output terminal provided on the pack case via
The secondary battery houses a power generating element formed by laminating sheet-like positive and negative electrode plates in an outer case in which peripheral portions of a pair of laminate sheets are welded and sealed, and a positive electrode lead and a negative electrode are welded and sealed from one side. A battery pack, wherein a lead is drawn out, and the battery protection device is provided on one side of the secondary battery from which the positive electrode lead and the negative electrode lead are drawn out.

2. The battery pack according to claim 1, wherein the circuit board is disposed at a position where its plate surface direction is parallel to the direction of the uneven surface of the secondary battery and overlaps at least a part of the welded seal portion of the outer case. .

A battery protection device is disposed near the lower case in the pack case, and the positive electrode connection member and the negative electrode connection member connected to the circuit board, and the positive electrode lead and the negative electrode lead are respectively positioned at positions closer to the upper case. 3. The battery pack according to claim 1, wherein the battery pack is connected, and a welding seal portion of the battery is disposed between the lead connection position and the battery protection device.

4. The circuit board according to claim 1, wherein one side of the circuit board is formed as a component mounting surface, and the other side is formed as a soldering surface, and the soldering surface is disposed with the open side of the lower case facing. The battery pack according to the item.

The battery pack according to any one of claims 1 to 4, wherein a soldering surface of the circuit board is coated with an insulating material after completion of the connection processing.

The PTC element is formed in a plate shape, and is arranged at a position where the plate surface direction is parallel to the uneven plane direction of the secondary battery and overlaps at least a part of the welded seal portion of the outer case. The battery pack according to claim 1.

A secondary battery formed in a flat plate shape, and a battery protection device configured with a circuit board formed with a protection circuit for protecting at least the secondary battery are housed in a pack case, and the secondary battery is In a battery pack formed by connecting the extracted positive electrode lead and negative electrode lead to a positive external output terminal and a negative external output terminal provided in a pack case via the battery protection device,
The secondary battery, a power generating element housed in the outer case comprising a pair of laminate sheet, composed of welded seal portion of the welded sealed one side is drawn positive electrode lead and the negative electrode lead,
The positive external output terminal and the negative external output terminal are mounted and fixed on the side of the pack case on the side of the lead lead-out side,
The secondary battery and the external output terminal, such that the circuit board has a plate surface direction parallel to the plate surface direction of the secondary battery, and overlaps at least a part of the welded seal portion of the outer case. Arranged between
The battery protection device is disposed on one side in the thickness direction in the pack case, and the positive electrode connection member and the negative electrode connection member connected to the circuit board and the positive electrode lead and the negative electrode lead are positioned on the other side in the thickness direction in the pack case. Position, the welding seal portion of the outer case is disposed between the lead connection position and the battery protection device,
The battery pack, wherein the positive external output terminal and the negative external output terminal are connected to a circuit board at respective extending portions .

Battery protection device is provided with a PTC element, the PTC element is formed in a plate shape, and at least a portion of the weld seal portions of the plate surface direction is parallel to the flat plate surface direction of the secondary battery, and the outer case 8. The battery pack according to claim 7 , wherein the battery pack overlaps and is disposed on one side of the same side as the circuit board in the thickness direction in the pack case .