%0 Journal Article %A Emma J Hopkins %A Sarah Frisco %A Ryan T Pekarek %A Caleb Stetson %A Zoey Huey %A Steven Harvey %A Xiang Li %A Baris Key %A Chen Fang %A Gao Liu %A Guang Yang %A Glenn Teeter %A Nathan R Neale %A Gabriel M Veith %B Journal of The Electrochemical Society %D 2021 %G eng %N 3 %P 030534 %R 10.1149/1945-7111/abec66 %T Examining CO₂ as an Additive for Solid Electrolyte Interphase Formation on Silicon Anodes %V 168 %8 01/2021 %! J. Electrochem. Soc. %X

We demonstrate that the addition of CO₂ to a standard 1.0 M LiPF₆ 3:7 wt% ethylene carbonate:ethyl methyl carbonate electrolyte results in the formation of a thinner insoluble solid electrolyte interphase (SEI) that is dominated by the presence of LiF. In contrast, cells without CO₂ result in a thicker insoluble SEI layer containing more organic constituents. The CO₂ is incorporated in the dimethyl carbonate soluble part of the SEI composed primarily of polymeric poly(ethylene oxide) (PEO) on the surface of a thin inorganic layer. This combination of properties from CO₂ addition provides an improved cycling performance through the reduction of irreversible side reactions, leading to higher coulombic efficiency. The results indicate that CO₂ incorporates into the SEI and plays a role similar to additives like fluorinated ethylene carbonate and vinylene carbonate with respect to polymeric components.