Beneficial effect of incorporating particle nanocrystalline and V3+ doping into high-energy-density LiMn0.8Fe0.2PO4 for lithium-ion batteries

Olivine-structured LiMnPO 4 -based cathode materials have been considered upgrades to LiFePO 4 due to their higher energy density and highly stable polyanionic Li + storage structure. However, the high electronic and ionic insulation has severely limited their popularization and application. In this work, the reversible specific capacity and the rate performance of LiMn 0.8 Fe 0.2 PO 4 @C (LMFP@C) have been promoted by incorporating particle nanocrystalline and V 3+ doping. The mechanical liquid phase activation technique ensures the uniform mixing of the raw materials and reduces their particle size to nanometer scale. Based on this typical synthetic strategy, about 1 at.% of V 3+ can be doped into the LMFP lattice to form a uniform solid solution , while most of the V 3+ ions tend to enrich on the surface of the particles as the introducing amount is >2 at.%. Optimally, 1 at.% of V 3+ doping improves the electrochemical performance of LMFP@C significantly, but >2 at.% of V 3+ introduction is detrimental. The optimized material exhibits high discharge capacities of 155.4 and 115.9 mAh·g −1 at 0.1 and 5.0C, respectively, and a high capacity retention of 93.4% after 100 cycles at 1.0C rate.