Dual Modification of Olivine LiFe0.5Mn0.5PO4 Cathodes with Accelerated Kinetics for High-Rate Lithium-Ion Batteries

Developing olivine-type lithium ferromanganese phosphates with high ionic/electronic conductivity is vital to promote their practical application in long-life and high-rate lithium-ion batteries (LIBs). Herein, we propose a dual modification strategy combining C-coating and Nb-doping and apply it to enhance LiFe0.5Mn0.5PO4 cathode materials. The uniform and compact C-coating layer successfully fabricates the high-speed conductive network among primary particles and meantime prevents the attack of electrolytes. The strong Nb–O coordination can effectively accelerate ion diffusion and electron transport within the nanoparticles while suppressing the Jahn–Teller effect of Mn3+. The dual modifications synergistically improve the LiFe0.5Mn0.5PO4 cathode materials with superior lithium-storage capacities of 152 and 115 mAh g–1 at 0.1 and 5 C, respectively. Furthermore, it exhibits an impressive cycling performance with an ultrahigh capacity retention of 95.4% after 1000 cycles at 1 C. These findings extend the application of surface-to-bulk co-modification in developing novel cathode materials used in high-performance LIBs.