| The world faces a catastrophic challenge of fossil fuel depletion and global warming.New energy vehicles can replace traditional fuel vehicles to a certain extent to alleviate the pressure of oil shortage and improve environmental pollution.The annual sales of new energy vehicles should reach 25 percent of the total by 2025,according to a draft of the New Energy Vehicle Industry Development Plan（2021-2035）released by China’s Ministry of Industry and Information Technology.Therefore,it is imperative to concentrate on research and development of new energy vehicles.Centering on the core issue of"energy saving"of new energy vehicles,we applied the newly developed two-dimensional material RGO and Mo S2 composite and RGO and SnS2composite to the anode of lithium-ion battery using in electric vehicle.In this paper,the working mechanism of chain-like linker and annular linker was studied deeply,and a new type of linker was proposed.First principles calculation method was mainly used in the research process and was compared with the experimental work.The main contents are as follows:（1）We found a chain-like polymer linker,PEI,using to binding molybdenum disulfide and reduced oxide graphene.Through first principles calculation,we explored the PEI linker can enhance the bonding energy between Mo S2 and RGO.Using first principles calculation,we explored the working mechanism of the linker PEI,and revealed how PEI plays the role of connection from the micro level.At the same time,the binding energy and lithium storage sites of the composites before and after the addition of PEI linker were compared.It is confirmed that the addition of PEI can improve the binding energy and add more lithium storage sites,so as to enhance the stability of the composites used as the anode of lithium-ion batteries and improve the reversible capacity of the batteries.（2）A novel chain-like linker was designed,which could effectively combine two-dimensional graphene with molybdenum disulfide to achieve the optimal binding effect and carry more lithium storage capacity of materials.Through first-principles calculation,the optimal structure of monomer linker and polymer linker containing equidistance carbon atoms were found respectively.Then,we studied the connection between the 11 different branches and Mo S2 and the connection between the different branches and RGO（G,RGO-OH,RGO=O）.Finally,we design a new linker which is more reasonable than the existing PEI linker.At last,the lithium storage performance of the new designed linker was tested.This work provides an idea and new method for the design of two kinds of two-dimensional material linker.（3）The method of how to regulate the growth direction of tin disulfide on the surface of RGO through ring linker was proposed.The working mechanism of annular linker 3-aminophenol（AP）connecting the SnS2 and RGO was revealed by calculation.The change of binding energy and lithium storage location of the composites before and after the introduction of AP linker and without AP linker were compared.It is found that AP linker can regulate the vertical or horizontal growth direction of SnS2 on the surface of RGO,and can also enhance the stability of the composites and provide more lithium storage locations. |
