Effect of SiO2 coating on microstructure and electrochemical properties of LiNi0.5Mn1.5O4 cathode material

We present a simple method for producing SiO2 modified LNMO cathode materials. Manganese carbonate was directly mixed with nickel nitrate and lithium hydroxide, and a spherical structure LNMO cathode material was prepared by two-step calcination, then ethyl orthosilicate and LNMO powder were simply mixed in solid and liquid phase to prepare SiO2-coated LNMO material. The effect of SiO2 coating on the structure of LNMO was studied by XRD, SEM, TEM, TG-DSC. An amorphous SiO2 coating layer developed on the surface of the LNMO particles in the modification, and this could alleviate the strike of HF caused by electrolyte decomposition as well as the development of a solid electrolyte interphase. The electrochemical performance of the coated material was as follows: when the amount of SiO2 was 0wt%, 1wt%, 2wt% and 3wt%, the initial discharge capacity of the sample was 98.2, 84.1, 101.3 and 89.8mAh·g−1, respectively. After 50 charge-discharge cycles, the capacity retention rates are 92.7%, 66.8%, 97.9% and 93.8%, respectively. The cyclic stability of the samples can be significantly improved when the SiO2 coating amount is 2wt% and 3wt%, indicating that SiO2 coating can not only improve the discharge specific capacity of the material, but also improve its cyclic stability.