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.