Self-Polymerized Cr–Sr Co-Doped LiNi ₀ . ₅ Mn ₁ . ₅ O ₄ : Synergistic Enhancement of Structural Stability and CV-Quantified Li ⁺ Diffusivity for 5 V Long-Cycle High-Rate Performance

content on the crystal surface, avoiding the dissolution side reactions of manganese at the electrode-solution interface, thereby enhancing cycling capacity stability during charge-discharge processes. At 1C and 5C rates, the discharge capacities were 132 mAh/g and 127 mAh/g, respectively. After 200 cycles at 1C, the capacity remained at 121 mAh/g, with a capacity retention of 91.67%, indicating that Cr-Sr doping via the self-polymerization method significantly improves the electrochemical performance.