Improving the cycling stability and rate capability of LiMn0.5Fe0.5PO4/C nanorod as cathode materials by LiAlO2 modification

Abstract

LiMn0.5Fe0.5PO4 (LMFP)@C and LMFP@LiAlO2@C nanorods are successfully synthesized by a solvothermal process followed by a calcination at H2/Ar atmosphere. The carbon coating and LiAlO2 coating does not change the morphology and particle size of LMFP, and all samples show nanorod morphology with 50–100 nm in width and 200–300 nm in length. The results show that LiAlO2 coating can offer rapid charge transfer channels with improved intercalation/de-intercalation kinetics of Li ions, which make an outstanding rate capability and cycling stability of as-synthesized LMFP@LiAlO2@C cathodes. As a result, LiAlO2 coating effectively improves the rate capability and cycling stability of LMFP cathode even at high discharge rates. Hence, LMFP@LiAlO2 (5 wt%)@C indicates an outstanding rate performance with a reversible discharge capacity of 137.6 and 113.2 mAh g−1 discharged at 0.05 C and 5 C rates, and the composite also shows a good cycle performance with an excellent capacity of 107 mAh g−1 and 86.4% capacity retention rate at 5 C rate after 100 cycles. Therefore, the LiAlO2 coating can be considered as an effective way to improve the electrochemical properties of LMFP.