First-principles Calculation Of Interface Structure And Performance Of Doped Diamond Composite Lithium Metal Solid Electrolyte

In order to clarify the effect of nano-diamond film as a lithium-sulfur battery SEI in inhibiting lithium dendrites,it is necessary to study the deposition behavior of lithium ions on the surface of the lithium negative electrode after passing through the nano-diamond SEI during battery cycling.This project explores the adsorption and migration behavior of lithium atoms on the surface of H defect diamond,B/P/S doped diamond surface and Li terminated diamond surface through the first-principles calculation method.Based on these behavioral characteristics,the feasibility of using various types of diamond surfaces as SEI for lithium-sulfur batteries is analyzed.The results of the study are as follows:(1)The calculation results of Li atoms on the H-defect diamond surface show that the adsorption of lithium atoms on the surface of the hydrogen-terminated diamond with hydrogen deficient hydrogen in the direction of the dimer is more stable.The adsorption of lithium atoms on the surface of the three-hydrogen-depleted hydrogen-terminated diamond is more stable.Lithium atoms cannot be adsorbed on the diamond surface with hydrogen termination.Lithium atoms have low adsorption energy on clean diamond surfaces.The H termination of the H-deficient center on the diamond surface can drive the deposition of Li atoms.After adsorption,lithium atoms form van der Waals bonds with carbon atoms on the diamond surface.Lithium atoms can easily migrate on the clean diamond surface.By comparing seven kinds of diamond surfaces,the clean diamond surface has the smallest lithium atom migration barrier and strong adsorption,making it the most suitable as SEI.(2)The calculation results of Li atoms on the B/P/S doped diamond surface show that the hydrogen-terminated doped diamond surface is easier to deposit lithium atoms than the clean doped diamond surface.The B-doped diamond surface is easier to deposit lithium atoms than the other two(P/S)element-doped diamond surfaces.Doping elements can drive all hydrogen to stop the adsorption of lithium atoms on the diamond surface.Compared with the three doping elements of B/P/S,lithium atoms are more likely to migrate on the surface of S-doped diamond.By comparing six types of diamond surfaces,the P-doped all-hydrogen-terminated diamond surface can take into account both the stable adsorption of lithium atoms and the lower migration barrier of lithium atoms.Therefore,it is most suitable as SEI.(3)The calculation results of Li atoms on the lithium-end diamond surface show that the migration of Li atoms between the lithium-end diamond interfaces tends to migrate to the P4 position.When lithium atoms migrate between the lithium-end diamond interfaces,they will guide the evolution of the lithium termination layer.Compared with the lateral migration of lithium atoms between the lithium-end diamond interface,it is easier for lithium atoms to achieve a longitudinal transition above the lithium termination layer.