Cupric ion substituted LiFePO4/C composites with enhanced electrochemical performance for Li-ion batteries

Cupric ion substituted LiFePO4/C composites were successfully synthesized via a two-step solid state reaction method. The SEM mapping demonstrates that cupric is well substituted in LiFePO4. Interestingly, the XRD spectra indicate that the substituted cupric could enlarge the interplanar distance of planes that parallelled to [010] direction of LiFePO4 crystallines, which could widens the diffusion channels of Li+ along [010] direction. For further research, Lithium ion storage behavior of as-synthesized cupric ion substituted LiFePO4/C products were investigated via various electrochemical strategies, and the highest capacity of 152.4, 144.4, 126.7 and 110.5 mAh g−1 was achieved by LiFe0.985Cu0.015PO4/C at discharge rate of 1, 2, 5, and 10 C, respectively. Compared the result with that of LiFePO4/C, we can see that cupric ion substituted LiFePO4/C composites show enhanced electrochemical activity for Li+ storage with decreased overpotential and increased high rate capability for electrochemical reaction.