Enhancement the cycling stability of the nickel-rich cathode material LiNi0.9Co0.01Mn0.09O2 by Nb5+ doping

LiNixCoyMn1-x-yO2 cathode materials have long been recognized as one of the most promising candidates for lithium-ion batteries. In order to increase production capacity and reduce costs, NCM cathode materials are currently developing in the direction of high nickel and low cobalt. However, these cathodes face serious challenges, such as structural instability, capacity fade, and poor rate capability. Despite extensive research, problenms of structural degradation and capacity loss under high-voltage conditions remain unresolved. In this work, we successfully prepared Nb5+-doped LiNi0.9Co0.01Mn0.09O2 cathodes by incorporating Nb2O5 into the Ni0.9Co0.01Mn0.09(OH)2 precursor powders. The Nb5+ doping not only expands the spacing of lithium layers, facilitating the diffusion of lithium ions, but also forms Nb-O bonds, enhancing the structural stability and improving the cycle performance. Electrochemical tests indicate that at a doping ratio of 1%, the first discharge specific capacity of the modified sample is 178.55 mAh/g at 1.0 C, with a capacity retention ratio of 92.69% after 100 cycles. Furthermore, the initial discharge specific capacity of the NCM-1.0Nb sample is up to 215.58 mAh/g at a high voltage of 2.5–4.5 V, and after 100 cycles, it is 188.73 mAh/g, with a cycle retention rate of 87.54%. The electrochemical cycling performance of NCM is significantly improved after doping Nb5+. Therefore, appropriate Nb5+ doping is a convenient and effective modification approach to obtain nickel-rich cathodes with excellent performance.