Operando studies of solid electrolyte interphase (SEI) formation with the electrochemical-Surface Force Balance (e-SFB)

Abstract

This study demonstrates the utility of the electrochemical-surface force balance (e-SFB) for observing solid electrolyte interphase (SEI) formation directly at an electrode surface. Through proof-of-concept measurements of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) based electrolytes, absolute thickness and mechanical properties of SEIs are measured in-situ before and after electrochemical cycling. The SEIs that formed in these systems were found to have thickenesses on the order of 100s of nm and elastic moduli on the order of 10s of MPa depending on cycling conditions and the nature of the solvent.