Achieving superior high-rate cyclability of LiNi0.5Mn1.5O4 cathode material via constructing stable CuO modification interface

Abstract

The spinel LiNi0.5Mn1.5O4 (LNMO) is an attractive high-voltage cathode material for commercial lithium-ion batteries because of its high energy density and low cost. However, surface side reactions and Mn dissolution during the cycling process damage the electrochemical performances of the material, especially at high rates. In this paper, the CuO coating is successfully constructed to stabilize the surface structure of LNMO. The CuO layer increases the degree of disorder phase and acts as a stable shell to inhibit the dissolution of Mn. The CuO-coated samples present the excellent rate performance and cyclability. Even at 10C rate, the CuO-coated LNMO (Cu 0.8 wt%) exhibits a high initial capacity of 128.7 mAh g−1 with a capacity retention rate of 95.3% after 100 cycles at 3.5–4.8 V. A series of test results demonstrate that the excellent performance is attributed to the CuO coating enhancing the structural stability of the material and improving the diffusion rate of lithium ion.