Electrolyte Design Enabling Stable Solid Electrolyte Interface for High-Performance Silicon/Carbon Anodes.

Silicon (Si)-based materials have been considered as one of the most promising anodes for the development of high-energy-density lithium-ion batteries (LIBs). However, poor interfacial stability and structural degradation are critical challenges for the successful application of Si-based anodes in LIBs. Herein, the use of a novel fluorinated carbonate (trifluoropropylene carbonate, TFPC) with high reduction potential and rapid film-forming ability as an electrolyte cosolvent is reported, which overcomes the deterioration of the electrode structure that hinders the battery quality. X-ray photoelectron spectroscopy combined with Fourier transform infrared spectroscopy technology investigated the composition and distribution of the solid electrolyte interface (SEI) layer formed on the Si/C anode. Notably, a stable SEI with an organic and inorganic bilayer structure was formed in this electrolyte design, and excellent mechanical properties and ionic conductivity were achieved. Moreover, the Li intercalation mechanism is elucidated by in situ Raman characterization. Benefited from this unique SEI, the Si/C-based batteries exhibit compelling cycling and rate performance. This work provides an in-depth understanding of the Li intercalation mechanism of the Si/C electrode, as well as a novel electrolyte, for high-performance LIBs.