Chloroethylene carbonate, a solvent for lithium ion cells, evolving CO2 during reduction

We have investigated the role of chloroethylene carbonate (CIEC) on the formation of the solid-electrolyte interfacial film on graphite electrodes for rechargeable lithium-ion cells. In situ infrared spectroelectrochemical experiments have been correlated with galvanostatic charge/discharge measurements. During the first reduction of graphite in a CIEC-based electrolyte, a sloping potential plateau from 1 .7 to l .4 V vs Li/Li + appears, which we relate to the generation of CO 2 . We assume that the CO 2 generated from CIEC is an intermediate reduction product that undergoes further reactions that contribute to the formation of the protective film.