Electrochemical properties of tungsten doped LiNi0.9Co0.1O2 lithium-ion battery cathode materials

Abstract

High-nickel layered cathode materials for lithium-ion batteries have received widespread attention in new energy vehicles for their excellent specific energy and cost advantages, and are considered to be the most promising cathode materials for high-energy density lithium-ion batteries. Despite its many advantages, poor thermal stability and rapid capacity degradation have greatly limited its large-scale application. Ion doping is considered to be an effective way to improve its drawbacks, and in this paper, a series of W-doped LiNi_0.9Co_0.1O₂ cathode materials were prepared using WO₃ as a tungsten source. Among them, 1 mol% W doping was the most effective, and its reversible capacity of 204.44 mA g ⁻¹ still had 93.25 % capacity retention after 100 this cycles at 1C. Combined with DFT calculations, it is found that the introduction of W does not change the original layered structure and the material transitions from semi-metallic to metallic at lower doping concentrations, resulting in more electrons occupying the Fermi energy levels to enhance its electrical conductivity and leading to an elevated spin state and a lower oxidation state of Ni.