摘要 |
The occurrence of micro-crack is prevented at the root of a thermally sealed area of casing materials even if a thick electric device element is sealed. Film covered battery 10 has cell element 13 to which leads 12 a, 12 b are connected, and casing films 11 for sealing cell element 13 with leads 12 a , 12 b extended therefrom. Casing films 11 are thermally sealed along the periphery to seal cell element 13 . Thermally sealed area 13 of casing films 11 is positioned between both surfaces of cell element 13 in the thickness direction of cell element 13 . On a side of casing films 11 from which leads 12 a , 12 b are not extended, close contact zone 15 , in which casing films 11 are not thermally sealed to each other but are in close contact with each other, is formed continuously to a space which receives cell element 13 . Close contact zone 15 has a length of one-half or more of the distance from one end to the other end of an inner edge of thermally sealed area 14.
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