Abstract:

Lithium manganese iron phosphate (LiMn_1-y Fe _y PO₄), which has a higher energy density than conventional lithium iron phosphate (LiFePO₄), is expected to provide enhanced endurance and higher output power for electric vehicles and portable electronics. However, the Jahn-Taylor effect associated with manganese and the consequential dissolution problems have yet to be resolved, which has severely hindered the widespread commercialization of LiMn_1-y Fe _y PO₄ as a cathode material. In this research, we introduced a core-shell structural-design strategy that resulted in the successful fabrication of two composite materials: LMFP55/C and LMFP64/C. These composites feature a unique configuration, with LiFePO₄ particles tightly and uniformly encapsulated on the surface of a LiMn_0.7Fe_0.3PO₄ core. This innovative approach effectively neutralized the negative impact of elemental Mn while simultaneously boosting the overall performance of the materials, particularly in terms of cycling stability. Notably, the LMFP64/C composite exhibited the impressive initial-discharge capacity of 154 mAh/g at 0.1 C, and it maintained the capacity-retention rate of 92% after 500 cycles at 1 C, which demonstrates its exceptional cycling stability.

Key words: LiMn_1-y Fe _y PO₄, high-temperature solid-phase method, cathode material, lithium-ion batteries