LiFePO4/(C+Cu) composite with excellent cycling stability as lithium ion battery cathodes synthesized via a modified carbothermal reduction method

In order to improve the electronic conductivity of lithium iron phosphate (LiFePO4), copper was added to modify LiFePO4/C composite as cathode material for lithium-ion battery, which was successfully synthesized via a modified carbothermal reduction method using a low cost Fe3+ salt (Fe (NO3)3) as iron source. The morphology, particle size and electrochemical performances of olivine LiFePO4 modified with carbon and copper were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and galvanostatics tests. The results show that the prepared composites were irregularity sphere with size of 100-200 nm, which were relatively even-distributed copper particles coated with a 3 nm carbon layer. The as-prepared composites exhibit an initial discharge capacity of 160.7 mA h g-1 at current density of 0.1 C-rate, the capacity retention ratio is 98.6% at 0.5 C-rate after 200 cycles, and 96% at 5 C-rate after 500 cycles, respectively. The impedance tests reveal that the addition of copper further reduces the electric resistance of LiFePO4/C. The well-designed synthesis method is hopeful to be applied to prepare other electrode materials of LIBs.