General Motors Corp. and A123Systems will co-develop battery cells based on A123’s nanophosphate battery chemistry. The cells are intended for use in the Chevy Volt concept car and other vehicles that use GM’s E-Flex electric drive system. The firms said their partnership should expedite development of batteries for electric plug-in vehicles and fuel cell variants of the E-Flex architecture.
GM believes that A123System’s nanophosphate-based cell technology, provides higher-power output, longer life and safer operations over the life of the battery compared with other lithium-ion (Li-ion) cell chemistries.
Earlier this year, GM awarded battery pack development contracts that require the integration of multiple battery cells. The contracts went to Compact Power, a subsidiary of Korean battery manufacturer LG Chem, and Continental Automotive Systems. Compact Power will use battery cells developed by LG Chem and Continental will use the cells developed by GM and A123.
Li-ion technology typically uses active electrode materials with particles that range in size from 5 microns to 20 microns, but A123Systems offers non-combustible active materials composed of particles smaller than 100 nm. The firm claims that faster kinetics in its storage electrode provide higher power than possible from other chemistries; its electrode and cell designs offer high thermal conductivity and low impedance compared with other batteries of similar size, and its electrolyte system operates over a wider temperature range. The firm said batteries made from its nanoscale electrode material are 80% lighter and offer higher charge/discharge rates (charging to high capacity in five minutes or less) and longer cycle life compared to nickel metal hydride (NiMH) batteries.
According to A123Systems, conventional Li-ion cells extract only half their lithium content when they reach their upper cut-off voltage. In contrast, A123 materials are designed to ensure that all lithium is extracted from the cathode when the battery is fully charged, thus safety issues related to overcharging are eliminated.