V-Doping-Mediated Li3VO4 Modification to Enhance the Cycling Stability of Li1.2Mn0.6Ni0.2O2

Abstract

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 Li_1.2Mn_0.6Ni_0.2O₂, leveraging their compatible properties to form a stable interface and address related challenges. An epitaxially grown Li₃VO₄ coating on Li_1.2Mn_0.6Ni_0.2O₂ 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 Li_1.2Mn_0.6Ni_0.2O₂ effectively lower the surface oxygen activity, further preventing oxygen release and irreversible phase transitions. In the assembled half-cell tests, 3 wt % Li₃VO₄-coated Li_1.2Mn_0.6Ni_0.2O₂ 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.