Preparation of Single-Crystal Li-Rich Mn-Based Layered Oxides with Excellent Electrochemical Performance via Simple Stepwise High-Temperature Sintering

Li-rich Mn-based layered oxides have attracted extensive attention in lithium-ion battery cathode materials due to their high specific capacity, wide operating voltage, and low cost. However, the large-scale production of single-crystal Li-rich Mn-based layered oxides remains a significant challenge. Herein, the morphology, structure, and electrochemical properties of a series of samples (Li_1.2Ni_0.13Co_0.13Mn_0.54O₂) prepared by the solid-state method and the molten-salt flux method were assessed. Single-crystal particles exactly could be prepared by potassium chloride (KCl), but its electrochemical performance was inferior and the molten-salt flux method was too complicated for industry. Surprisingly, we found that water washing and annealing processes could enhance the cycling performance. Furthermore, single-crystal Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ with a particle size of 536 nm was successfully prepared by simple stepwise sintering (950 °C for 7 h, 1000 °C for 1 h, and 850 °C for 2 h), which delivered a specific capacity of 274.9 mAh·g^-1 between 2.0 and 4.8 V at 0.1 C with 77.4% initial Coulombic efficiency and 82.1% capacity retention after 100 cycles at 0.1 C. This study may provide theoretical guidance for the industrial production of single-crystal Li-rich Mn-based layered oxides.