Abstract: A battery having a housing, a core assembly, a separator and a top cover assembly is provided. The housing defines an accommodating cavity for receiving the core assembly. The core assembly has a jelly-roll having a body portion, and an insulating sheet. The body portion has a top end surface and a bottom end surface located at the ends of the body portion respectively, and a peripheral surface connected to the top the bottom end surfaces. The insulating sheet covers the peripheral surface and/or the bottom end surface. The separator is in the housing and separates the bottom end surface of the jelly-roll from a bottom surface of the housing. The top cover assembly is connected to the housing in a sealed manner and configured to close the opening of the housing. The top cover assembly is spaced from the insulating sheet.