Synergistic integration of internal gradient-doping and external coating for superior performance in lithium-rich Mn-based cathodes

Abstract

Key obstacles to commercializing lithium-rich manganese-based cathodes (LRMs) include voltage decline and capacity loss due to irreversible structural damage. The integration of structural design with surface modification to enhance structural stability represents the optimal choice for addressing these challenges. Here, an H⁺/Li⁺ exchange interface treatment and subsequent thermally driven process achieves external LiMgPO₄ coating and internal gradient Mg doping of LRMs. The “pillars effect” achieved through Mg doping reduce the irreversible oxygen release and inhibits the migration of transition metals, and the LiMgPO₄ coating layer mitigates interfacial reactions. As a result, the dual-form incorporation of Mg components, synergistically enhances the electrochemical performance of LRMs for Li-ion batteries. The modified sample exhibits an improved capacity retention from 68.8 % to 85.3 % after 250 cycles compared to the pristine LRMs, and demonstrates a high specific discharge capacity of 155.8mAh g⁻¹ at 5C. This work provides a valuable new idea for improving the comprehensive electrochemical performance of LRMs through a synergistic integration strategy that encompasses both internal doping and external coating factors of Mg components.