Enhancing the High Rate Capability and Cycling Stability of LiMn2O4 by Coating of Solid-State Electrolyte LiNbO3

To study the influence of solid-state electrolyte coating layers on the performance of cathode materials for lithium-ion batteries in combination with organic liquid electrolyte, LiNbO₃-coated Li_1.08Mn_1.92O₄ cathode materials were synthesized by using a facile solid-state reaction method. The 0.06LiNbO₃–0.97Li_1.08Mn_1.92O₄ cathode exhibited an initial discharge capacity of 125 mAh g^–1, retaining a capacity of 119 mAh g^–1 at 25 °C, while at 55 °C, it exhibited an initial discharge capacity of 130 mAh g^–1, retaining a capacity of 111 mAh g^–1, both at a current density of 0.5 C (where 1 C is 148 mAh g^–1). Very good rate capability was demonstrated, with the 0.06LiNbO₃–0.97Li_1.08Mn_1.92O₄ cathode showing more than 85% capacity at the rate of 50 C compared with the capacity at 0.5 C. The 0.06LiNbO₃–0.97Li_1.08Mn_1.92O₄ cathode showed a high lithium diffusion coefficient (1.6 × 10^–10 cm² s^–1 at 55 °C), and low apparent activation energy (36.9 kJ mol^–1). The solid-state electrolyte coating layer is effective for preventing Mn dissolution and maintaining the high ionic conductivity between the electrode and the organic liquid electrolyte, which may improve the design and construction of next-generation large-scale lithium-ion batteries with high power and safety.