Submicron single-crystalline LiNi_0.5Mn_1.5O₄ cathode with modulated Mn³⁺ content enabling high capacity and fast lithium-ion kinetics

Disordered single-crystalline LiNi_0.5Mn_1.5O₄ (LNMO) cathode materials with different Mn³⁺ contents were prepared by a simple temperature control strategy of a solid-state reaction. The effects of the mutual modulation of the Mn³⁺ content and the bulk microstructure on the crystal structure and electrochemical properties of LNMO were systematically investigated. Results showed that a suitable Mn³⁺ content can enhance the structural stability and alleviate structural degradation and capacity fading. The excellent performance originates from the simultaneous inhibition of microcrack formation and side reaction with electrolytes, ensuring the rapid diffusion of Li⁺ during extraction and insertion. Consequently, the LNMO-800 sample delivers an excellent cycling stability with a capacity retention of 98.37% after 200 cycles, remarkable rate capacity of 115 mAh·g⁻¹ at 10.0C, and rapid Li⁺ diffusion coefficient of 4.43 × 10^–9 cm²·s⁻¹. This work will allow for a deeper understanding of the coupling effect between Mn³⁺ content and bulk microstructure, especially in the design and development of Mn-based cathode materials.