A lithium battery employs for a battery separator and a battery insulating packing and the like a battery polymeric material comprising repeating units wherein p-phenylene is combined with one type of group selected from the group composed of oxygen, a methylene group, an isopropylidene group, a carbonyl group, a carbonyldioxy group, a carboxylic acid anhydride group, an amide group, an ureylene group and a sulfonyl group, or a polymeric material comprising at least two types of repeating units wherein p-phenylene is combined with one type of group selected from the group composed of oxygen, a methylene group, an isopropylidene group, a carbonyl group, a carbonyldioxy group, a carboxylic acid anhydride group, an amide group, an ureylene group, a sulfonyl group, sulfur and a carbonyloxy group.