Influence of Li3V2(PO4)3 complexing on the performance of LiMnPO4 based materials utilized in lithium ion battery

LiMnPO4/C, LiMn0.8Fe0.2PO4/C, and corresponding composites with nominal formula of 0.8LiMnPO4·0.2Li3V2(PO4)3/C and 0.8LiMn0.8Fe0.2PO4·0.2Li3V2(PO4)3/C are synthesized via high temperature solid-state reaction. According to refinement results, the phase ratios of olivine and NASICON in 0.8LiMnPO4·0.2Li3V2(PO4)3/C and 0.8LiMn0.8Fe0.2PO4·0.2Li3V2(PO4)3/C are 84.2:15.8 and 81.2: 18.8, respectively. Complexing Li3V2(PO4)3 plays negligible influence on discharge capacity when cycled between 2.5 and 4.4 V vs. Li+/Li. Instead, this strategy significant improves the rate capability of phosphate composites. The discharge capacities of composites at 2 C are 103.8 and 117.6 mA h g−1, which are much higher than those of corresponding olivine counterparts, namely 35.3 and 91.1 mA h g−1.