US Patent 7410724 Film packaged battery having a cupped portion

A battery is fabricated on the basis of at least one of the following four concepts, i.e., lead terminals passing through a package not lower than the uppermost surface of an electrolyte cell, lead terminals projecting from a package in directions opposite to each other, a film package with a crushed portion expandable for accumulating gas and sheets of gas barrier sealant for keeping the boundaries between component parts of a package sealed; the seal is hardly broken so that the battery is durable and highly reliable.