Hitachi Maxell, Limited

Megumu Takai

Toshikazu Yoshiba

Akira Asada

Tadashi Sakata

Yuko Onishi

Keiji Nakamura

Yoshifumi Sakamoto

Masanori Sugano

A flat nonaqueous secondary battery with improved reliability is provided. The flat nonaqueous secondary battery () includes an electrode assembly disposed in a space formed by an exterior case () and a seal case (). The electrode assembly includes a plurality of positive electrodes () and a plurality of negative electrodes () alternately stacked upon each other and a separator (). The separator () has a joint () formed by welding together at least a portion of its periphery. When the separator () and the positive electrode () are measured along a cross section in their thickness direction, the ratio A/B of the shortest distance A between the end of the joint () of the separator () facing the positive electrode () and the outer periphery of the positive electrode () sandwiched by the separator () to the thickness B of the positive electrode () is not smaller than 1.

Flat nonaqueous secondary battery

A non-aqueous liquid electrolyte cell comprising a positive electrode which has a metal oxide as an active material, a negative electrode, and a non-aqueous liquid electrolyte, in which the metal oxide has an average particle size of 40 to 150 &mgr;m, and the volume of the liquid electrolyte is 0.9 to 1.25 times as large as the volume of the metal oxide, which has good characteristics even at low temperature.

Non-aqueous liquid electrolyte cell

Growing community of inventors

Otokuni-gun, Japan

Megumu Takai