Patent ID: 7887941

Claim:
An apparatus comprising: a plurality of battery cells, wherein one or more of said plurality of battery cells is provided with a gas discharge valve; a battery pack which is mounted in an electronic device upon being used, comprising: an inside battery compartment which accommodates therein a part of the plurality of battery cells and is located inside an outline of a body of the electronic device when the battery pack is mounted on the electronic device; and an outside battery compartment which mounts therein a remainder of the plurality of battery cells and is located outside the outline of the body of the electronic device; and a partition wall structure which is arranged between the inside battery compartment and the outside battery compartment, wherein the partition wall structure comprises: a fireproof wall layer which does not melt at a temperature of gas discharged from a gas discharge valve; and a heat insulating layer comprising a plurality of holding walls forming a cantilever structure disposed between said fire proof wall layer and said outside battery compartment.