Meticulous customization of electrolyte solvation structure achieving the compatibility of sulfolane-based electrolyte with SiOx anodes

SiO x anode offers high theoretical capacity, enhancing the energy density of lithium-ion batteries. However, traditional electrolytes fail to form an effective solid electrolyte interphase on SiO x , necessitating electrolyte modification. Sulfone-based electrolytes are crucial for high-voltage electrolyte designs due to superior oxidation stability. Therefore, a tailored sulfone electrolyte for SiO x is essential to leverage its potential and match it with high-voltage cathodes. Herein, we report the design of a high-voltage-resistant, non-flammable sulfone-based locally high-concentration electrolyte (1.0 M LiTFSI +0.2 M LiDFOB in SL/HFE/FEC). The locally high-concentration design effectively addresses the high viscosity and low wettability issues of sulfone solvents. Furthermore, by optimizing salt concentration and employing additive engineering, we precisely controlled the organo-inorganic ratio of the SEI, resulting in the formation of a robust inorganic layer and a tough organic layer. This approach effectively suppressed the capacity drop observed during the long-cycle tests, allowing the SiO x ||Li half-battery to achieve a cycle life exceeding 750 cycles with an average coulombic efficiency of 99.7 %. Additionally, this electrolyte enhances the passivation effect of the cathode electrolyte interphase, enabling the SiO x ||NCM811 full battery to stabilize at 4.5 V.