Li-ion battery modules can run vehicles

Panasonic Corp. has put together a 1.5kWh battery module from 18650-type (18 mm in diameter x 65 mm in length) Li-ion battery cells, such as used in laptop computers. The module can be used to provide energy storage solutions for a wide range of environmentally friendly energy technologies. For example, multiple units can be connected in series or in parallel to store energy generated by home-use photovoltaic systems and fuel cells, and power electric vehicles.

Amid rising environmental concerns such as CO₂ emissions, great expectations are placed on widespread use of renewable energy technologies such as photovoltaics and commercialisation of electric vehicles to alleviate the concerns. However, these technologies require storage systems to become commonplace in daily life. Among a number of energy storage technologies, storage systems using Li-ion batteries in particular are considered promising and practical, because such systems are lighter and have greater capacity than those using other types of rechargeable batteries.

As applications of the storage systems using Li-ion batteries increase, there will arise demand for such systems with higher capacity, output, reliability and safety as well as improved cost performance. Flexibility in voltage and capacity will also be required according to the application.

Panasonic's compact and high-energy battery module meets such demands. The module occupies a volume of approximately 7L and weighs 8kg. It has a voltage of 25.2 V and a capacity of 58Ah. By connecting several modules users can construct battery packs for a variety of applications, such as home electricity storage and electric vehicles.

The high-energy module is constructed from 140 pieces of 18650-type Li-ion battery cells—seven serially connected rows with each row made of 20 parallel connected battery cells. This structure avoids prevents system performance failure even if some individual cells fail.

To achieve the innovative module, Panasonic employed a high-capacity and high-durability cell technology using its proprietary nickel-based positive electrode material. Other technologies used include its cell safety technology that uses a heat-resistant insulating layer between the positive and negative electrodes to prevent short circuits and thermal runaway (overheating) which can be caused when foreign particles get mixed into the battery cell. The new module also uses Panasonic's design technology to ensure reliability by minimising the effects on power supply if a trouble occurs in some of the cells contained in the module.

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