LITHIUM ION SECONDARY BATTERY

To provide a lithium ion secondary battery which has flexibility and allows a good output characteristic to be achieved even in a high-output charge/discharge operation.SOLUTION: A lithium ion secondary battery according to an embodiment hereof comprises an electrode sheet 10 having: a current collector layer 14 integrated with an exterior packaging film 12; an electrode layer 16 containing active material particles 20 and a polymer solid electrolyte 22 filling gaps among the active material particles; and a separator layer 18 containing inorganic oxide particles 24 and a polymer solid electrolyte 22 filling gaps among the inorganic oxide particles. The polymer solid electrolyte 22 contains a lithium salt, an ionic liquid and a high-molecular weight polymer.SELECTED DRAWING: Figure 2 【課題】可撓性を有するとともに高出力の充放電でも良好な出力特性が得られるリチウムイオン二次電池を提供する。【解決手段】実施形態に係るリチウムイオン二次電池は、外装フィルム１２に一体化された集電体層１４と、活物質粒子２０と該活物質粒子の隙間を埋める高分子固体電解質２２とを含む電極層１６と、無機酸化物粒子２４と該無機酸化物粒子の隙間を埋める高分子固体電解質２２とを含むセパレータ層１８と、を有する電極シート１０を備える。高分子固体電解質２２はリチウム塩とイオン液体と高分子ポリマーとを含む。【選択図】図２