An electrolyte for SiOx/LiNi0.5Mn1.5O4 batteries

Abstract The Li-ion batteries composed of high-capacity SiO x anode and high-potential LiNi 0.5 Mn 1.5 O 4 cathode is the most realistic options to meet the increasing demands for higher-energy-density storage systems. However, the absence of electrolytes covering the multifaceted issues from highly reducing and oxidizing conditions at the SiO x anode and LiNi 0.5 Mn 1.5 O 4 cathode, respectively, has limited its applications. Herein, we present an electrolyte that can solve these issues simultaneously. A concentrated LiN(SO 2 F) 2 /methyl (2,2,2-trifluoroethyl) carbonate electrolyte upshifts the reaction potentials of the SiO x anode and enables an earlier formation of a robust anion-derived passivation film upon charge to diminish the reductive degradation of the electrolyte. The weak solvating ability of the electrolyte provides a high oxidation tolerance against Al corrosion and transition metal dissolution from the cathode material. Excellent long-term cycling of 5 V-class SiO x |LiNi 0.5 Mn 1.5 O 4 full cells (96% capacity retention after 500 cycles at a low constant current of 0.5 C-rate) was achieved.