Li–Nb–O Coating/Substitution Enhances the Electrochemical Performance of the LiNi0.8Mn0.1Co0.1O₂ (NMC 811) Cathode

High-nickel layered oxides, such as NMC 811, are very attractive high energy density cathode materials. However, the high nickel content creates a number of challenges, including high surface reactivity and structural instability. Through a wet chemistry method, a Li–Nb–O coated and substituted NMC 811 was obtained in a single step treatment. This Li–Nb–O treatment not only supplied a protective surface coating but also optimized the electrochemical behavior by Nb5+ incorporation into the bulk structure. As a result, the 1st capacity loss was significantly reduced (13.7 vs 25.1 mA h/g), contributing at least a 5% increase to the energy density of the full cell. In addition, both the rate (158 vs 135 mA h/g at 2C) and capacity retention (89.6 vs 81.6% after 60 cycles) performance were enhanced.