Enhanced Electrochemical Performance of 5V LiNi 0.5 Mn 1.5‐x Zr x O 4 Cathode Material for Lithium‐Ion Batteries

Abstract Series of LiNi 0.5 Mn 1.5‐x Zr x O 4 (x=0, 0.0025, 0.005, 0.01, 0.02) samples have been prepared by a combined coprecipitation‐hydrothermal method followed by two‐step calcination. The effects of Zr 4+ doping contents on the structure, morphology and electrochemical properties are studied. The results show that Zr 4+ doping reduces Mn 3+ content and Ni/Mn disordering degree. Additionally, Zr 4+ doping reduces primary particle size and agglomeration degree. More significantly, Zr 4+ doping leads to the appearance of higher‐surface‐energy {110} and/or {311} facets, while undoped sample only consists of {111} and {100} facets. But excessive Zr 4+ doping (x=0.02) leads to the decrease of higher‐surface‐energy facets. Electrochemical results show that appropriate Zr 4+ doping improves the rate and cycling performances of LiNi 0.5 Mn 1.5 O 4 material. Among them, LiNi 0.5 Mn 1.495 Zr 0.005 O 4 shows the optimal electrochemical performance, which can be attributed to high phase purity, high crystallinity, appropriate primary particle size and agglomeration degree, enlarged lattice constant, and greater exposure of {110} and/or {311} facets.