AlPO ₄ and Li ₃ PO ₄ Modified Lithium‐Rich Manganese Materials as a Cathode for High‐Performance Solid‐State Lithium Ion Batteries

Lithium‐rich manganese‐based materials (LRMs) with specific capacities exceeding 250 mAh g ⁻¹ due to additional contribution of anionic oxygen redox are a potential cathode for high energy solid‐state batteries (SSBs). Nevertheless, the inferior rate performance, severe capacity loss and interfacial degradation of cathode caused by the irreversible oxygen release pose a serious challenge. Here, a surface‐functionalized strategy are proposed to coat AlPO ₄ and Li ₃ PO ₄ (ALPO) synchronously on LRMs, which not only physically inhibits the release of oxygen, alleviating the structural degradation of LRMs, but also accelerates the kinetics of interfacial Li ⁺ transport. The solid‐state batteries with modified LRMs exhibits optimized rating performance with a reversible capacity of 216.7 mAh g ⁻¹ at 0.1 C and remarkable cyclability with lower capacity decay rate of 0.18% per cycle after 200 cycles at 0.5 C. Particularly, the solid‐state lithium‐ion full cells with modified LRMs cathode and Si/C anode exhibit an energy density of 334.7 Wh Kg ⁻¹ with 66.3% capacity retention after 60 cycles. Therefore, this method is of importance for suppressing irreversible oxygen release and guides the design of high‐capacity LRMs for solid‐state lithium ion batteries.