Effect of Al3+ and Al2O3 co-modification on electrochemical characteristics of the 5-V cathode material LiNi0.5Mn1.5O4

Abstract

Spinel LiNi0.5Mn1.5O4 (LNMO) materials with high voltage and positive cost performance have presented attractive prospects. In this study, an LNMO material was co-modified with Al3+ doping and Al2O3 coating via solid-state method and wet chemical method. The effect of Al3+ doping and different Al2O3 coating which were based on the LNMO samples with a doping content of x = 0.06 on the properties were discussed. Remarkably, the co-modification effect was most favorable when the coating content was 1 wt%; the retention rates after 100 cycles at 0.5C and 2C reached 99.1% and 91.7%, respectively, which can be ascribed to Al3+ doping improving the electronic conductivity of the material. Furthermore, Al2O3 coating can improve ionic conductivity; the LANMO-1 wt% sample got the best charge transfer resistance and Li+ diffusion coefficient. The Al2O3 layer can hinder the side reaction between the material and the electrolyte and reduce the polarization effect, thereby improving the cycle and rate performance of the material.