Bifunctional Modification of CF_x and Semihollow and Multiaperture Microsphere Structures for Lithium- and Manganese-Rich Layered Cathodes

Lithium- and manganese-rich layered cathodes (LMRs) have been widely investigated as promising cathode materials with high energy density and excellent electrochemical properties for Li-ion batteries. However, the practical application of LMRs has been greatly hampered by their structural collapse trend due to severe surface phase transitions, surface-side reactions, HF erosion, and the oxygen generated during the charging and discharging process. In this work, a collaborative solution for structural and surface modification was proposed to address the above issues, and an innovative in situ coating LMR was proposed. A semihollow porous microsphere Li1.2Mn0.54Ni0.13Co0.13O2 (H-LMR) was synthesized by combining a template-free rapid coprecipitation method with a high-temperature solid-state sintering method. LiF and C were generated using CFx in the first cycle of the battery, completing the in situ coating modification process. The collaborative solution mitigates structural expansion during the charging and discharging process while providing bidirectional ion channels as well as a suitable spatial basis for in situ-coated modification. This unique in situ-coated modification process greatly reduces the occurrence of surface-side reactions, reduces HF erosion, and further improves ionic conductivity. In addition, the synergistic effect further improves the specific discharge, specific capacity, and cycling stability of the material, resulting in a higher specific capacitance (313.1 mAh.g(-1)) at 0.1C, a good rate yield (182.7 mAh.g(-1) at 2C), and a long cycle life (90.96% capacity retention after 100 cycles at 0.5C). The proposed scheme provides a new direction and a better path for high-energy-density lithium-ion battery materials in the future.