High Cycle Life Cathode for High Voltage (5V) Lithium Ion Batteries
Technical Report,16 Jan 2011,16 Jan 2011
Army Research Laboratory Adelphi
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There is a huge, growing demand in commerce and the military for high energy density rechargeable batteries. In response to this need, we have developed a high voltage, high cycle life Li-ion cathode material based on lithium cobalt phosphate LiCoPO4 that provides higher energy density 15 LiFePO4 demonstrated, up to 40 greater with further RD. The invention combines the safety of a phosphate system with a high energy content. Safety advantage arises from abuse tolerance of phosphate. Previous attempts to use LiCoPO4 have generally resulted in rapid charge capacity fade and an extremely short cycle life e.g., greater than 50 percent loss after only 10 cycles. The innovation is the partial substitution of lithium and cobalt by iron, which stabilizes electrochemical cycling and greatly reduces capacity loss. The capacity retention is more than 80 percent after 500 cycles with high coulombic efficiency.