Improved cycling performance of Si nanoparticle anodes via incorporation of methylene ethylene carbonate

• Effects of MEC on cycling ability of Si nanoparticle anodes was investigated.
• MEC greatly improved capacity retention of Si anode compared to standard electrolyte.
• High concentration of poly(MEC) was found in MEC-derived SEI.

Methylene ethylene carbonate (MEC) has been investigated as an alternative additive to fluoroethylene carbonate (FEC) for Si nanoparticle anodes cycled with 1.2 M LiPF6/ethylene carbonate (EC): diethyl carbonate (DEC) (1:1, w/w) electrolyte. The Si electrodes cycled with 10% MEC-added electrolyte exhibit significantly improved capacity retention after 100 cycles compared to standard electrolyte (73% vs 46%). In addition, the Si electrode cycled with MEC additive has less damage from cracking than the standard electrolyte. Ex situ surface analyses via infrared and X-ray photoelectron spectroscopy reveal a solid electrolyte interphase (SEI) containing a high concentration of a poly(MEC), which is likely responsible for the improved performance of Si anodes.

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