Battery pack

摘要

The present invention relates to a battery using a case of which the section of the lower part containing an electric element is square or hexagonal and the section of the upper part containing a sealing plate is circular or elliptic. By virtue of the shape of the lower part the space efficiency of the battery pack is enhanced and by virtue of the shape of the upper part the productivity of the battery is improved. Further, preferably, the corners of the lower part of the case are rounded or chamferred, whereby the temperature rise in the battery pack is suppressed.