Construction of Core–Shell Structure Cobalt-Free Li-Rich Mn-Based Cathode Materials with Enhanced Electrochemical Performance

Li-rich Mn-based (LRM) cathode materials are considered highly promising candidates for the next generation of high-energy-density lithium-ion batteries, due to their exceptionally high specific capacity and low production costs. However, the expansion of microcracks caused by stress accumulation in the cathode particles during cycling significantly reduces the structural stability of the materials, leading to accelerated capacity and voltage degradation. In this study, a cobalt-free LRM cathode material with a core–shell structure (designated as Li-1.3) is successfully prepared using a high-temperature solid-phase method. This material demonstrated a high initial capacity of 247.5 mAh g⁻¹ at 0.1C and a capacity retention of 87.36% after 200 cycles, significantly outperforming the 79.74% retention seen in the solid structure material (designated as Li-1.5). Cross-sectional SEM and 3D nano-CT analyses demonstrate that the core–shell structure effectively alleviates stress accumulation during cycling through its mechanical support effect, thereby suppressing the formation of microcracks. This work offers a novel structural design strategy for developing highly stable LRM cathode materials.