V-Doping-Mediated Li₃VO₄ Modification to Enhance the Cycling Stability of Li_1.2Mn_0.6Ni_0.2O₂

Lithium-rich manganese layered (LMR) materials, utilizing the characteristics of both cation and anion redox, are promising cathodes for high-energy-density lithium-ion batteries. However, capacity fading and voltage decay pose challenges to their commercial applications. In this work, we employ chemical bonding to integrate Li3VO4 with Li1.2Mn0.6Ni0.2O2, leveraging their compatible properties to form a stable interface and address related challenges. An epitaxially grown Li3VO4 coating on Li1.2Mn0.6Ni0.2O2 crystals enhances stability at the electrode–electrolyte interface while also improving lithium-ion conduction. Additionally, the strong metal–oxygen bonds between the high-valence V element and Li1.2Mn0.6Ni0.2O2 effectively lower the surface oxygen activity, further preventing oxygen release and irreversible phase transitions. In the assembled half-cell tests, 3 wt % Li3VO4-coated Li1.2Mn0.6Ni0.2O2 exhibits excellent electrochemical performance. After 150 cycles at 200 mA g–1, the discharge specific capacity reaches 188 mA h g–1, with a capacity retention rate as high as 93%. Even under a high current density of 1000 mA g–1, the discharge specific capacity remains at 128 mA h g–1 after 200 cycles. This study highlights the significant impact of bonded lattice-matching materials, presenting a viable design strategy for developing high-performance LMR cathodes.