PURPOSE: To prevent firing or explosion of a battery due to overdischarge by contacting a positive electrode current collecting plate partially with an electrolyte or separator.

CONSTITUTION: A negative electrode 2 is made of metal lithium while a positive electrode 4 is formed from Mn dioxide, acetylene black, and binder. A pos. electrode current collecting plate 5 is made of a stainless steel whose inside is lined with an electroconductive carbon film, while a sealing material 6 consists of denatured polypropylene. The pos. electrode 4 is divided and arranged on the current collecting plate 5. In dividing of this current collecting plate 5, a projection 7 is provided, and part of the plate 5 is contacted with the electrolyte 3. Accordingly Li ions in the electrolyte 3 are educed to the projection 7 at the time of overdischarge, and the current collecting plate 5 and neg. electrode 2 are connected, i.e., shortcircuited, to present the same form as external shortcircuiting, which should prevent firing and explosion.