BATTERY PACK

PROBLEM TO BE SOLVED: To provide a battery pack having high reliability and excellent high temperature storage characteristics.SOLUTION: Disclosed is a battery pack in which a plurality of square secondary batteries 20 are laminated via a space 31. The square secondary battery 20 includes a square outer package 12 in which a wound electrode body 4 and a nonaqueous electrolyte containing fluorosulfonic acid lithium are housed. The square outer package 12 has a bottom part 12c, a pair of large area side walls 12a, and a pair of small area side walls 12b. The spacer 31 has a body part 31a, a lower side wall part 31b arranged so as to be opposed to the bottom part 12c of the square outer package 12, and a pair of side wall parts 31c arranged so as to be opposed to the small area side walls 12b of the square outer package 12. 【課題】信頼性が高く、高温保存特性に優れた組電池を提供する。【解決手段】複数個の角形二次電池２０がスペーサ３１を介して積層された組電池であって、角形二次電池２０は、巻回電極体４とフルオロスルホン酸リチウムを含有する非水電解質を収納する角形外装体１２を備え、角形外装体１２は、底部１２ｃと、一対の大面積側壁１２ａと、一対の小面積側壁１２ｂを有し、スペーサ３１は、本体部３１ａと、角形外装体１２の底部１２ｃと対向するように配置される下側壁部３１ｂと、角形外装体１２の小面積側壁１２ｂと対向するように配置される一対の側壁部３１ｃを有する組電池。【選択図】図６