Synergistic In Situ Mg Doping and Li₂MnO₃ Coating toward High-Performance Lithium-Rich Manganese-Based Cathodes

Lithium-rich, manganese-based layered oxides are among the most promising cathode materials for next-generation lithium-ion batteries (LIBs), offering high reversible capacity, elevated operating voltage, and cost-effectiveness compared to conventional cathodes. However, their practical application is hindered by irreversible lattice oxygen loss and structural degradation during cycling. In this work, Li1.2[Mn0.54Ni0.13Co0.13]O2 was modified via in situ Mg2+ doping and uniform Li2MnO3 surface coating to address these challenges. The dual-modified material was systematically investigated through theoretical analysis and validated experimentally using structural, morphological, and electrochemical characterization techniques. Electrochemical evaluations revealed that the synergistic effect of Mg2+ doping and Li2MnO3 coating significantly improved the material's performance, delivering a high discharge capacity of 193.9 mAh/g at 1C and an impressive capacity retention of 86.4% after 200 cycles. Additionally, the 52.73% reduction in voltage fade achieved through Mg2+ doping and Li2MnO3 coating further confirms the enhanced interfacial stability and significantly improved long-term cycling durability of the modified electrode.