Enhanced rate and high-temperature performance of La0.7Sr0.3MnO3-coated LiNi0.5Mn1.5O4 cathode materials for lithium ion battery

Abstract

La0.7Sr0.3MnO3-coated 5 V spinel LiNi0.5Mn1.5O4 as cathode is prepared by mixing LiNi0.5Mn1.5O4 powders and the sol–gel-drived La0.7Sr0.3MnO3 matrix, followed by high-temperature calcinations. The effect of La0.7Sr0.3MnO3-coating on the electrochemical performances of LiNi0.5Mn1.5O4 cells, especially at elevated temperature, is investigated systematically by the charge/discharge testing, cyclic voltammograms and AC impedance spectroscopy, respectively. Compared to pristine LiNi0.5Mn1.5O4, La0.7Sr0.3MnO3-coated material has much lower surface and charge-transfer resistances and shows a higher lithium diffusion rate. The results of electrochemical experiments demonstrate that the modified material exhibits remarkably enhanced electrochemical reversibility and stability at elevated temperature. The La0.7Sr0.3MnO3-coating layer protected the surface of the active materials from HF in the electrolyte during electrochemical cycling. As a result, the electrochemical cycling stability is improved.