Matsushita Battery Industrial (MBI), a division of Matsushita Electric Industrial Co., said Monday it had established a mass-production system for a lithium-ion battery that incorporates the technology to ensure safety. The new batteries, according to the company, will never overheat or explode.

MBI has succeeded in improving the safety by forming a heat resistance layer (HRL) consisting of an insulating metal oxide on the surface of the electrodes. Lithium-ion batteries contain a thin polyolefin separator to insulate the cathode from the anode. When a separator is pierced by an electrically conductive material such as a metal particle, a short-circuit develops, causing the battery to overheat and, in the worst case, catch fire. The HRL used in the Panasonic battery, however, has better insulating and heat-resistant characteristics than polyolefin (polyethylene and/or polypropylene) used typically. Even if a short-circuit occurs, it will cease without causing the battery to overheat, the company behind Panasonic brand-name said.

Earlier this year Sony had to recall 9.6 million batteries for notebooks because on certain occasions microscopic metal particles in the recalled battery cells might come into contact with other parts of the battery cell (e.g. anode and cathode come into contact), leading to a short circuit within the cell. Typically, a battery pack would simply power off when a cell short circuit occurs. However, under certain rare conditions, an internal short circuit might lead to cell overheating and or even flaming, the company indicated.

MBI has taken measures to prevent lithium-ion batteries from contaminating with electrically conductive materials by eliminating foreign substances from battery materials and creating a clean environment in the battery factory. Considering contamination with such substances, the company has adopted stronger separators and thermally stable materials. Demand for more safety and capacity, however, called for the development of a new technology. The HRL is a product of MBI’s research and development of battery technology and its focus on safety as a first priority.

The company began shipping the industry's first 2.9Ah (the capacity of 18650 cylindrical lithium-ion battery mainly used for notebook PC) high capacity batteries in April this year and is now ready to mass-produce the products.