Role of 1,3-Propane Sultone and Vinylene Carbonate in Solid Electrolyte Interface Formation and Gas Generation

Lithium-ion coin cells containing electrolytes with and without 1,3-propane sultone (PS) and vinylene carbonate (VC) were prepared and investigated. The electrochemical performance of the cells is correlated with ex situ surface analysis of the electrodes conducted by Fourier transform infrared and X-ray photoelectron spectroscopies and in situ gas analysis by online electrochemical mass spectrometry (OEMS). The results suggest that incorporation of both PS and VC results in improved capacity retention upon cycling at 55 °C and lower impedance. Ex situ surface analysis and OEMS confirm that incorporation of PS and VC alter the reduction reactions on the anode inhibiting ethylene generation and changing the structure of the solid electrolyte interface. Incorporation of VC results in CO₂ evolution, formation of poly­(VC), and inhibition of ethylene generation. Incorporation of PS results in generation of lithium alkylsulfonate (RSO₂Li) and inhibition of ethylene generation. The combination of PS and VC reduces the ethylene gassing during formation by more than 60%.