Rare earth metal La-doped induced electrochemical evolution of LiV3O8 with an oxygen vacancy toward a high energy-storage capacity

Abstract

Due to its high theoretical capacity (∼280 mA h g⁻¹), lithium vanadium oxide (LiV₃O₈) is considered a promising electrode material for meeting the demands for a longer battery life. However, it still suffers from an inferior cycling stability and rate properties. Benefitting from the unique traits of rare earth metal La, La-doping was introduced to V-sites, leading to an expansion of the lattice volume and reduced particle size, and bringing about more oxygen defects for fast ion redox reactions. The considerable discharge capacity of optimized La-doped LiV₃O₈ could reach up to 308 mA h g⁻¹, and the capacity could be kept at 252 mA h g⁻¹ after numerous loops. Supported by a detailed analysis of the capacity curves, an improved redox activity of V⁵⁺ was strongly demonstrated. Moreover, compared to the basic materials, an increasing rate capacity located in the low potential range was detected, ascribed to the existence of an oxygen vacancy, enabling a reduction in the energy barrier and a broadening of the energy distribution. Interestingly, La-doping could ultimately improve the capacity and is thus worth further exploration, particularly for the design of advanced cathodic materials.