Robust Solid/Electrolyte Interphase (SEI) Formation on Si Anodes Using Glyme-Based Electrolytes

Silicon (Si) is the most naturally abundant element possessing 10-fold greater theoretical capacity compared to that of graphite-based anodes. The practicality of implementing Si anodes is, however, limited by the unstable solid/electrolyte interphase (SEI) and anode fracturing during continuous lithiation/delithiation. We demonstrate that glyme-based electrolytes (GlyEls) ensure a conformal SEI on Si and keep the Si fracture-free. Benchmarking against the optimal, commonly used carbonate electrolyte with the fluoroethylene carbonate additive, the Si anode cycled in a GlyEl exhibits a reduced early parasitic current (by 62.5%) and interfacial resistance (by 72.8%), while cell capacity retention is promoted by >7% over the course of 110 cycles. A mechanistic investigation by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy indicates GlyEl enriches Si SEI with elastic polyether but diminishes its carbonate species. Glyme-based electrolytes proved to be viable in stabilizing the SEI on Si for future high energy density lithium-ion batteries.

Automated summary

The study demonstrates that glyme-based electrolytes can effectively improve the stability and cycling performance of silicon anodes in lithium-ion batteries, reducing early parasitic current, decreasing interfacial resistance, and promoting capacity retention. Mechanistic investigation shows that GlyEl enriches the SEI on silicon with elastic polyether while diminishing carbonate species, making it a viable option for future high energy density lithium-ion batteries.