Contribution of calcium ion doping to the rate property for LiFe0.5Mn0.5PO4/C

Exotic atom doping is one of the crucial measures to improve the electrochemical performance of electrode materials. The calcium-doped LiFe0.5Mn0.5PO4@C (LFMP/C-Ca) was effectively fabricated by high temperature solid-state reaction. The XRD Rietveld refinement results show that calcium ion doping increases the lattice parameters of the LFMP/C. Compared to LFMP/C, the LFMP/C-3Ca provides superior cycling stability and rate property. The galvanostatic intermittent titration (GITT) results show that LFMP/C-3Ca possesses a larger lithium-ion diffusion coefficient than LFMP/C. The experimental results show that LFMP/C-3Ca possesses a superior electronic conductivity, which is also proved by density function theory (DFT) calculations. At high rates, the discharge specific capacities of LFMP/C-3Ca are 105.7 mAh g−1, 94.7 mAh g−1, 84.9 mAh g−1, 70.8 mAh g−1 and 53.1 mAh g−1 at 10C, 20C, 30C, 40C, 50C, respectively. Therefore, the appropriate calcium doping is helpful to improve rate performance of LiFe0.5Mn0.5PO4@C.