Improved electrochemical performance and capacity fading mechanism of nano-sized LiMn0.9Fe0.1PO4 cathode modified by polyacene coating

Abstract

Nano-sized LiMn_1−xFe_xPO₄ (x = 0 and 0.1) was prepared by a solvothermal method in a mixed solvent of water and ethanol. LiMn_0.9Fe_0.1PO₄–polyacene (PAS) composite exhibits a high conductivity (0.15 S cm⁻¹), resulting in an excellent rate performance and good cycle life. The LiMn_0.9Fe_0.1PO₄–PAS composite delivers a discharge capacity of 161, 141, and 107 mA h g⁻¹ at 0.1 C, 1 C and 10 C, respectively. The well-distributed conductive polyacene surrounding the LiMn_0.9Fe_0.1PO₄ nanoplates enhances the electronic contact of the nanosized crystalline particles and suppresses the manganese dissolution related to the structure evolution during cycling. Specifically, the manganese dissolution, electrolyte decomposition and the antisite defects are the most significant factors that impact the capacity degradation of olivine iron-doped lithium manganese phosphate cathode materials.