Synergistic enhancement of Li-rich manganese-based cathode materials through single crystallization and in-situ spinel coating

Lithium -rich manganese -based cathode (LRM) materials are considered the most promising cathode for the nextgeneration high -energy -density Li -ion batteries due to their high specific discharge capacity. However, the current mainstream LRM materials exhibit a polycrystalline morphology, and the degradation of this morphology during extended cycling exacerbates structural distortions, leading to poor cycle stability. Herein, a spinel phase encapsulated single -crystal LRM material with a particle size of about 500 nm is prepared through a simple molten -salt assistant solid-state synthesis method utilizing traditional polycrystalline LRM precursor, followed by boric acid treatment. Combined with various characterizations, the surface coating layer of obtained singlecrystal LRM materials is identified as spinel Li4Mn5O12 with a thickness of about 5 nm, which effectively enhances Li+ diffusion kinetics. Benefited from the collaborative strategy of single crystallization and spinel coating which strength Li+ conduction and suppresses particle cracking, the single -crystal LRM materials achieve a specific discharge capacity of 296.3 mAh g-1 at 0.1 C (1 C = 250 mA g-1), yielding a capacity retention of 97.4% after 300 cycles at 1 C. This study offers a universal and easy industrial scale -up approach for developing singlecrystal LRM cathode materials with long cycling stability, which promotes the commercial utilization of singlecrystal LRM cathode.