Reduced Graphene Oxide/LiMgPO₄ Double Layer-Coated Li-Rich 0.4Li₂MnO₃·0.6LiMn_1/3Ni_1/3Co_1/3O₂ for High Performance Cathode

Lithium-rich layered oxides (LLOs) have emerged as highly promising cathode materials for lithium-ion batteries due to their high specific capacity and cost-effectiveness. However, structural changes, oxygen release, and transition metal dissolution during cycling lead to irreversible voltage decay and capacity degradation, posing significant challenges for their practical application. While surface coatings with metal oxides offer partial mitigation, their poor electronic conductivity compromises rate capability and cycle stability. To tackle this challenge, we introduce an innovative dual-layer coating strategy by sequentially coating LLO (Li_1.2Mn_0.6Ni_0.2Co_0.2O₂) particles with an ion-conductive LiMgPO₄ (LMP) inner layer and a conductive reduced graphene oxide (rGO) outer layer. The LMP layer mitigates electrolyte-induced side reactions, while the rGO layer enhances electron transport, synergistically improving the performance. This synergistic design enables the optimized LLO@LMP@rGO cathode to achieve 80% capacity retention after 200 cycles at 1 C (vs 31% for pristine LLO) and an impressive high-rate capacity of 145 mA h g^-1 at 8 C. The straightforward fabrication process, involving coprecipitation and thermal reduction, underscores its scalability for industrial production. Our work not only offers a viable pathway to enhance LLO cathodes but also inspires interfacial engineering strategies for advanced battery systems.