Li+ and PO43– Codoping Synergy to Enhance the Cycling Stability and Rate Capacity of Spinel LiMn2O4 Cathode for Lithium-Ion Batteries

Spinel LiMn2O4 cathode possesses open three-dimensional ion transport channels, high safety, and abundant resources, making it a promising candidate for high-power lithium-ion batteries. However, spinel LiMn2O4 inevitably faces serious challenges of manganese dissolution and irreversible phase transitions during the electrochemical process, leading to rapid capacity decay and limiting its rate performance. Herein, we report a simple two-step solid-state sintering method to realize Li+ and PO43– codoping synergy in spinel LiMn2O4. It is found that PO43– doping not only expands the lattice parameters of the material, enhancing its charge-transfer kinetics but also increases the relative content of active Mn3+, improving the specific capacity of spinel LiMn2O4. Meanwhile, Li+ doping effectively enhances the stability of the spinel structure, and the irreversible phase transition from cubic phase to tetragonal phase could be effectively suppressed in spinel LiMn2O4. Consequently, benefiting from the synergistic effect of Li+ and PO43– codoping, the optimally codoped spinel LiMn2O4 electrode delivers high specific discharge capacities of 116 and 102 mA h g–1 at 1 and 20C, respectively, and achieves 78.1% capacity retention after 1000 cycles at 5C. This strategy provides an effective modification approach to developing advanced electrode materials for lithium-ion batteries.