Adsorption and 2-Dimensional Association of Lithium Alkyl Dicarbonates on the Graphite Surface through O-Li+ (arene) Interactions
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abstract
Adsorptions of several lithium alkyl (vinylene, divinylene, ethylene, and propylene) dicarbonates on the surface of hydrogen-truncated carbon clusters (C 54 H 18 , C 78 H 20 , and C 96 H 32 ) are investigated using density functional theory. Lithium alkyl dicarbonates resulting from the reductive decomposition of the respective organic carbonates can be adsorbed on the graphite surface mainly through OLi + (arene) interactions, yielding structures with Li + oriented toward the hexane ring center. The adsorption energies of lithium vinylene dicarbonate (LVD), lithium ethylene dicarbonate (LED), and lithium propylene dicarbonate (LPD) on the basal plane of neutral as well as negatively charged C 54 H 18 , and on the edge plane of the negatively charged C 78 H 22 , agree within 4.0 kcal/mol, e.g., they are -34.67, -37.40/-35.17 and -38.05 kcal/mol on the basal plane of the negatively charged C 54 H 18 , respectively; however, the distances from both the carbonyl carbons and alkyl carbons to the nearest graphite carbon clearly increase in the sequence LVD < LED < LPD. In addition, the favorable conformation of LVD is basically parallel to the graphite surface, while those of the latter two dicarbonates are considerably twisted. Adsorption of the trimers for lithium vinylene/ethylene/ propylene dicarbonates on the basal plane of C 96 H 22 are also discussed. The present results can partially explain several important phenomena occurring in Li-ion batteries.
