Prop-1-ene-1,3-sultone as interfacial-engineering additive in nonflammable electrolyte for 4.45 V LiCoO2/Si-Graphite lithium-ion batteries with high performance

Abstract

To achieve high energy density for lithium-ion batteries, employing high-voltage cathodes and Si-based anodes is available. Fluoroethylene carbonate-based electrolytes show potential for use in high-voltage lithium-ion batteries due to their superior oxidation stability. However, fluoroethylene carbonate is prone to reductively decompose on the anode and brings about adverse effects on the battery performance. In this work, prop-1-ene-1,3-sultone is incorporated as an efficacious film-forming additive into fluoroethylene carbonate/dimethyl carbonate electrolyte for the purpose of ameliorating the compatibility with Si-Graphite anode in high-voltage lithium-ion batteries. The flame retardant (ethoxy)pentafluorocyclotriphosphazene is also incorporated into the electrolyte to guarantee the nonflammable feature. This nonflammable electrolyte has an ideal conductivity higher than 8 mS cm−1 at 25 °C, and it grants competitive performances to a high-voltage LiCoO2/Si-Graphite pouch cell. This cell after 300 cycles test exhibits a capacity retention of over 80 % at 1C, and the discharge capacity at 8C exceeds 50 % of that at 1C. By virtue of X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy techniques, it is confirmed that prop-1-ene-1,3-sultone enhances interfacial properties of Si-Graphite anode and contributes to an optimized interface, which restrains the volume expansion of Si-Graphite and inhibits persistently reductive decomposition of electrolytes.