Fabrication and electrochemical characterization of a novel spinel Li2Ni0.5Mn1.5O4 cathode coated with conductive glass for Lithium-ions batteries

A new spinel Li2Ni0.5Mn1.5O4 (LNMO) cathode reported in our previous work displays high initial specific capacity (260.4 mAh g−1) and good coulombic efficiency (92.2%), but suffers from low capacity retention of 80.2% after 50 cycles. In this paper, Li2O-0.2B2O3-1.8SiO2 (LBSO) glass phase surface modification is adopted to promote the electrochemical performance of LNMO. LBSO layer coated on the surface of LNMO cathode, as confirmed by SEM and HRTEM observation, can effectively prevent the cathode from dissolving in the electrolyte, therefore suppresses the increase in resistance and the degradation in Li-ions diffusion. Consequently, the electrochemical properties of the surface modified cathode material are improved. The initial specific capacity of 0.3 wt% LBSO coated LNMO is kept as 263 mAh g−1 with coulombic efficiency of 95%. Notably, the capacity retention after 100 cycles is improved from 69% to 83% by a comparison between the pristine and coated samples. Moreover, the coated cathode exhibits good rate performance, giving high specific capacity of 142 mAh g−1 even at a current density of 5C. All the results presented above suggest high potential for the material as candidate cathode for high energy density batteries.