In this study, first-principles calculations were performed to investigate the initial stage of ethylene carbonate (EC) decomposition on the stable (110)4 surface of LixCoO2 (LCO, x=0.67, 1). For the possible initial decomposition reactions of EC on cathode surfaces, H-abstraction reaction and ring opening reaction have been proposed5, 6 and investigated on LixMnO2 surfaces7, 8. For the adsorption models of EC on LCO (110) slab, parallel (Fig. 1a) and Oc-upward (Fig. 1b) configurations were adopted, and the corresponding reaction barriers of possible reactions in two configurations were calculated by density functional theory (DFT) calculations. Climbing image nudged elastic band (CINEB) method was used to search the transition state (TS) and minimum energy path (MEP) of certain reactions.
Based on the calculation results, H-abstraction reaction (ΔEbarrier = 0.96 eV) is prone to occurring in a parallel configuration on LCO (110), while ring opening reaction (ΔEbarrier = 0.89 eV) is favored in Oc-upward configuration. These predicted EC decomposition fragments may not be the final products of side reactions, which could also react with other adsorbed fragments, leading to the SEI formation. The following reactions are considered and discussed in the presentation.
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