BATTERY OPTIONS FOR HYBRID ELECTRIC VEHICLES

Batteries are a critical part of the drive train for hybrid electric vehicles and the majority of vehicles on the road at present use nickel/metal hydride batteries but these are expected to be displaced by lithium-based batteries in the near term as their technical performance is improved. Other chemistries, including lead/acid, may provide an energy storage option for this application. The key requirements of the battery system are described in detail. The battery undergoes repeated cycling at very high rates of discharge and recharge, needs to be kept cool and in order to be compact needs high power and energy density. Nickel/metal hydride batteries have been optimised for this duty cycle and the design and construction are discussed. Lithium-based batteries are under intensive development for hybrid electric vehicle applications. Their construction and the challenges for this type of duty cycle are discussed. Forecasts for the adoption of new chemistries are presented and directions for longer term developments outlined