Superior Electrochemical and Kinetics Performance of LiNi 0.8 Co 0.15 Al 0.05 O 2 Cathode by Neodymium Synergistic Modifying for Lithium Ion Batteries

Abstract

The nickel-rich layered cathode material LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) is receiving enormous attention for its high energy density and low cost. Nevertheless, its wide application is limited by its unsatisfactory cycle performance and rate performance. In this study, the synergetic modification of the Nd 2 AlO 3 N coating and Nd 3+ doping is realized to enhance the electrochemical performance of NCA. The Nd 2 AlO 3 N coating can protect the electrode-electrolyte interface and inhibit the side reactions. In the meantime, the Nd 3+ doping, with the larger ion radius of Nb 3+ and stronger Nd-O bond energy, can effectively enhance the kinetics performance and stabilize the crystal structure of the NCA cathode material. The modified materials with above characters demonstrate an excellent electrochemical stability and kinetics performance, among which the Nd4000 sample has the quite best performance, and its capacity/capacity retention still reach 168 mAh·g −1 /91% after 200 cycles, which are distinctly higher than the pristine 144.6 mAh·g −1 /78.5%. The electrochemical impedance spectra and cyclic voltammetry results also demonstrate that the charge transfer resistance and electrode polarization are suppressed with neodymium modifying during the cycle, and the lithium ion diffusion coefficient is significantly increased compared with the pristine sample.