Graphite-Embedded Lithium Iron Phosphate for High-Power-Energy Cathodes

Lithium iron phosphate (LiFePO4) is broadly used as a low-cost cathode material for lithium-ion batteries, but its low ionic and electronic conductivity limit the rate performance. We report herein the synthesis of LiFePO4/graphite composites in which LiFePO4 nanoparticles were grown within a graphite matrix. The graphite matrix is porous, highly conductive, and mechanically robust, giving electrodes outstanding cycle performance and high rate capability. High-mass-loading electrodes with high reversible capacity (160 mA h g-1 under 0.2 C), ultrahigh rate capability (107 mA h g-1 under 60 C), and outstanding cycle performance (>95% reversible capacity retention over 2000 cycles) were achieved, providing a new strategy toward low-cost, long-life, and high-power batteries. Adoption of such material leads to electrodes with volumetric energy density as high as 427 W h L-1 under 60 C, which is of great interest for electric vehicles and other applications.