Lithium-ion based batteries have found widespread popularity in all kinds of consumer electronics thanks to their high energy-to-weight ratios, lack of memory effect, and slow discharge when not in use. These attributes have also made them attractive to the burgeoning areas of battery-powered cars and storage of energy generated by home-use photovoltaic (PV) systems and fuel cells. This rise in popularity, and the increase in storage systems using lithium-ion batteries, has also led to a demand for systems with higher capacity, output, reliability, safety and improved cost performance. Now Panasonic says it has developed a 1.5 kWh battery module that meets these demands.

The new module has a volume of approximately seven liters, weighs eight kg (8.6 lbs), has a voltage of 25.2 and a capacity of 58 Ah. Multiple units of the module can be connected in series and/or parallel to construct battery packs for a range of applications. The high-energy module is constructed from 140 pieces of 18650-type (18 mm in diameter x 65 mm in length) lithium-ion battery cells - seven serially-connected rows each made of 20 parallel-connected battery cells. This structure enables the prevention of a serious loss in system performance such as system shutdown, even if some individual cells fail.

Panasonic says the 18650-type lithium-ion batteries are highly reliable and safe, and offer good cost performance - and the company has already developed and commercialized an 18650-type lithium-ion battery with the industry's highest level of capacity.

To develop the new module, Panasonic employed high-capacity and high-durability cell technology utilizing a proprietary nickel-based positive electrode material that boasts high capacity and excellent durability. Additionally, its cell safety technology uses a heat-resistant metal oxide insulating layer between positive and negative electrodes to prevent short circuits and overheating, which can occur when foreign particles get mixed into the battery cell.

Panasonic will have a prototype of the new battery module on show at CEATEC JAPAN 2009, which runs October 6-10, and at the New Energy Industry Fair Osaka, which runs from October 7-9.