Mg-doped LiMn0.8Fe0.2PO4/C nano-plate as a high-performance cathode material for lithium-ion batteries

Abstract

Lithium-ion battery cathode materials with the high-voltage platform have turned into research highlights. Manganese-based olivine material LiMn0.8Fe0.2PO4 (LMFP), which is synthesized by cheap and environmentally friendly raw materials as precursors, has received high attention due to the higher energy density than commercial lithium iron phosphate products. However, similar to the low conductivity of olivine-structured lithium iron phosphate (LiFePO4), the defect of low conductivity of LMFP has also become the obstacle of LMFP further application. To improve the kinetic properties of LMFP, Mg-doped LMFP/C nano-plate are forearmed by a straightforward and controllable solvothermal approach. The results demonstrate that Mg2+ can be validly doped into the sample, and can partially displace Li+ position in LMFP. It has been found that the Mg-doped LMFP/C material Li0.97Mg0.015Mn0.8Fe0.2PO4 (LMFP-2) presents excellent electrochemical performances and more sustainable application prospect in the fields of electric vehicle and grid energy storage batteries, which can provide a high initial discharge capacity of 156.9 mAh g−1 at 0.1C. In addition, even at high rates of 10 and 20C, the discharge capacity of LMFP-2 can still maintain 120.7 and 104.8 mAh g−1, where the discharge process can be completed in only 255 and 110 s. These results indicate that the introduction of Mg2+ at Li+ site can validly upgradation the electron conductivity and Li+ mobility in the material, thus promoting the electrochemical performances. The rapid discharge ability and cyclic performance of the as-prepared materials make them have great application potential in high-performance lithium-ion batteries.