Weakly solvated electrolyte enables the robust solid electrolyte interface on SiOx anodes for lithium-ion battery

Silicon oxide (SiO x ) anodes are considered to be the promising alternative to graphite anodes for lithium-ion batteries. However, the traditional carbonate electrolyte fails to generate the effective solid electrolyte interface (SEI) on SiO x anodes to well adapt the large volume expansion of SiO x particles. Herein, a weakly solvated perfluorinated electrolyte with dual lithium salts was designed to match SiO x anodes. The perfluorinated solvent with weakened solvation ability and the strong coordination of Li + -DFOB − and Li + -TFSI − lead to an anion-dominated solvated shell, which induces the formation of inorganics-rich SEI. The high-strength bonds (Li-F, B-F, B-O, B-N et al.) enable high mechanical strength and rapid ion migration of the SEI film, thereby effectively accommodating the volume expansion of SiO x and avoiding continuous decomposition of the electrolyte. Furthermore, as designed electrolyte also shows excellent flame retardancy and high voltage stability. Consequently, the SiO x anode exhibits remarkably improved cycling performance in contrast to that in traditional carbonate electrolyte, maintaining 1073.7 mAh/g after 300 cycles at 1.0 A/g when paired with metal Li, and presents excellent compatibility with commercial cathodes including LiFePO 4 and LiNi 0.8 Co 0.1 Mn 0.1 O 2 . This work provides a new inspiration and path for the design of electrolyte highly matched with silicon oxide anodes.