High‐Performance Single‐Crystal Lithium‐Rich Layered Oxides Cathode Materials via Na₂WO₄‐Assisted Sintering

Abstract

Single‐crystal lithium‐rich layered oxides (LLOs) with excellent mechanical properties can enhance their crystal structure stability. However, the conventional methods for preparing single‐crystal LLOs, require large amounts of molten salt additives, involve complicated washing steps, and increase the difficulty of large‐scale production. In this study, a sodium tungstate (Na2WO4)‐assisted sintering method is proposed to fabricate high‐performance single‐crystal LLOs cathode materials without large amounts of additives and additional washing steps. During the sintering process, Na2WO4 promotes particle growth and forms a protective coating on the surface of LLOs particles, effectively suppressing the side reactions at the cathode/electrolyte interface. Additionally, trace amounts of Na and W atoms are doped into the LLOs lattice via gradient doping. Experimental results and theoretical calculations indicate that Na and W doping stabilizes the crystal structure and enhances the Li+ ions diffusion rate. The prepared single‐crystal LLOs exhibit outstanding capacity retention of 82.7% (compared to 65.0%, after 200 cycles at 1 C) and a low voltage decay rate of 0.76 mV per cycle (compared to 1.80 mV per cycle). This strategy provides a novel pathway for designing the next‐generation high‐performance cathode materials for Lithium‐ion batteries (LIBs).