Elementary mechanism: nation with Li + and reduction. All reactions identified -dimerization and both decomposition mechanisms -involve relatively high energy barriers. Our understanding of the role of dioxolylidene in SEI formation remains incomplete, and further work must be done to elucidate its decomposition routes. However, if the barriers to dioxolylidene decomposition were lowered by e.g. a solvent effect or a reactive surface, the possibility exists for a catalytic loop in which dioxolylidene is repeatedly reformed via the reaction of CO 2 with Li + EC 2-or Li + CO - 2 with EC -.