A novel graphene modified LiMnPO4 as a performance-improved cathode material for lithium-ion batteries

A novel graphene-modified LiMnPO4 composite as a performance-improved cathode material for lithium-ion batteries has been prepared with LiH2PO4, Mn(CH3COO)2·4H2O, and graphite oxide (GO) suspension by spray-drying method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and galvanostatic charge-discharge tests are applied to characterize these materials. The structure analysis shows that LiMnPO4 sheets with width of 100-200 nm and thickness of 20-30 nm are attached to the graphene sheets in pieces. The graphene sheets with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during the discharge/charge process. The electrochemical tests show that the composite cathode material could deliver a capacity of 105.1 mAh/g at 0.05 C in the voltage range of 2.5-4.4 V. Moreover, the cells showed fair good cycle ability over 50 cycles.