Dicarboxylate-Substituted Ethylene Carbonate as an SEI-Forming Additive for Lithium-Ion Batteries

A novel five-membered cyclic carbonate, (4R,5R)-dimethyl 2-oxo-1,3-dioxolane-4,5-dicarboxylate (ODC), has been studied as a solid electrolyte interphase (SEI) forming additive. The influence of ODC on the performance of lithium ion cells has been evaluated in propylene carbonate (PC) based electrolyte and compared with that of vinyl ethylene carbonate (VEC), a commercial SEI-forming additive. Both additives prevent exfoliation of graphite by PC and provide the stable performance of Li/graphite cells. Compared to VEC, ODC provides superior cycling performance of graphite/LiNi0.65Co0.2Mn0.15O2 cells due to its stability toward oxidation. X-ray photoelectron spectroscopy has revealed that the surface compositions of both electrodes remain constant upon prolonged cycling of the graphite/LiNi0.65Co0.2Mn0.15O2 cell with ODC-containing electrolyte, while in the case of VEC significant deposition of electrolyte degradation products occurs on both electrodes.