Breaking Solvation Dominance Effect Enabled by Ion–Dipole Interaction Toward Long-Spanlife Silicon Oxide Anodes in Lithium-Ion Batteries

Micrometer-sized silicon oxide (SiO) anodes encounter challenges in large-scale applications due to significant volume expansion during the alloy/de-alloy process. Herein, an innovative deep eutectic electrolyte derived from succinonitrile is introduced to enhance the cycling stability of SiO anodes. Density functional theory calculations validate a robust ion-dipole interaction between lithium ions (Li⁺) and succinonitrile (SN). The cosolvent fluoroethylene carbonate (FEC) optimizes the Li⁺ solvation structure in the SN-based electrolyte with its weakly solvating ability. Molecular dynamics simulations investigate the regulating mechanism of ion-dipole and cation-anion interaction. The unique Li⁺ solvation structure, enriched with FEC and TFSI^-, facilitates the formation of an inorganic-organic composite solid electrolyte interphase on SiO anodes. Micro-CT further detects the inhibiting effect on the SiO volume expansion. As a result, the SiO|LiCoO₂ full cells exhibit excellent electrochemical performance in deep eutectic-based electrolytes. This work presents an effective strategy for extending the cycle life of SiO anodes by designing a new SN-based deep eutectic electrolyte.