Panasonic develops battery that won't overheat

Japan's Matsushita Electric Industrial Co. (Panasonic) said it has developed a lithium-ion battery that won't overheat even if a short circuit occurs.

The new battery includes a heat-resistive insulator inside the battery cell, next to an existing separator that insulates the anode and cathode. If that separator is punctured a short circuit occurs that typically causes the battery to overheat and in some circumstances catch fire. Panasonic said its insulator layer ensures that the battery won't overheat even in the event of a short circuit.

Panasonic's announcement responds to consumers' concern about the safety of lithium-ion batteries following a number of incidents involving them.

Earlier this year most major laptop computer makers started recall or exchange programs for batteries containing lithium-ion cells made by Sony after a number of batteries overheated and caught fire. Sony blamed the problem on metallic particles that got inside the battery during production, puncturing the separator layer and causing a short circuit. The replacement program covers 9.6 million batteries and will cost Sony up to ¥51 billion (US$432 million).

Then on Dec. 7, Japanese mobile-carrier NTT DoCoMo and handset-maker Mitsubishi Electric recalled 1.3 million cell-phone batteries made by Sanyo Electric, saying they could overheat and catch fire.

Panasonic's new batteries are made by another company in the Matsushita group, Matsushita Battery Industrial Co., and are ready for mass production, said Akira Kadota, a spokesman for Panasonic in Tokyo. The batteries aren't available directly to end users but are sold in bulk to electronics product manufacturers, so Panasonic wouldn't reveal their price. Kadota said they could be more expensive than current cells but could also work out cheaper if large orders are placed.

Matsushita Battery Industrial is one of the largest battery makers in Japan.