Rational Electrolyte Design to Form Inorganic–Polymeric Interphase on Silicon-Based Anodes

Silicon-based materials have been regarded as the most promising anodes for high-energy batteries, when combined with high- voltage/capacity nickel-rich layered cathodes. However, challenges arise from unstable electrode/electrolyte interphases on the anode and cathode as well as from safety hazards associated with highly flammable commercial electrolytes. Herein, we rationally design a nonflammable cyclic phosphate-based electrolyte to tune the electrode/electrolyte interphase components by controlling the reduction of a cyclic phosphate and Li salt. This strategy enables the electrolyte to form a highly elastic, robust inorganic–polymeric interphase on microsized silicon-based anodes that can accommodate the immense volume changes. Furthermore, by generating a stable polymeric interphase on the surface of the cathode as well, a SiO|LiNi_0.6Mn0.2Co_0.2O₂ cell demonstrated an extremely high energy density of ∼590 Wh·kg^–1 with 71.4% capacity retained over 300 cycles and high Coulombic efficiency of 99.9%. This interfacial regulation strategy is of vital importance for designing new electrolytes for high-energy-density batteries.