Lithium Ion Diffusion Mechanism Of Organic Covalent Framework Material Solid Electrolyte

Energy issues have always been an important issue of global concern.In the past few decades,lithium-ion batteries have been widely used as secondary energy storage devices worldwide.However,the safety of traditional lithium-ion batteries has always been concerned.The traditional organic electrolytes used in batteries have the risk of inflammation when shortcircuiting or damaged,making the development of new-generation batteries a research hotspot.All-solid-state Li-ion batteries(ASSLBs)are promising to be the next generation of secondary energy storage batteries with their better safety performance and energy density.Compared with the traditional lithium ion secondary battery,the ASSLBs replace the traditional organic liquid electrolytes and membrane with an all-solid electrolyte,which plays a role in facilitate lithium ion conduction and isolating the positive and negative electrodes from short circuit.The important role of all-solid electrolytes has attracted much attention in the development of ASSLBs.Traditional inorganic solid electrolytes are often complicated to prepare.,and they are often necessary to modify or add other materials to limit possible side reactions between interfaces or improve the unpromising ion-conduction in the bulk and on the interface.Different from traditional inorganic solid electrolytes covalent organic frameworks(COF)materials,and as organic materials,they have high potential design flexibility,stability and electrochemical stability,and often have porous properties.Such features make them ideal materials for solid electrolytes.Various COF materials have been applied as solid electrolytes in ASSLBs and have achieved good results.For example,COF-5 material exhibits a lithium ion conductivity of 2.6 in experimental tests,while having excellent chemical and electrochemical stability.However,the interaction between lithium ions and other ions or molecular and framework materials is not clear.Understanding the conduction mechanism and interaction of lithium ions significance for the subsequent design of new COF-based solid electrolyte materials is very important.In this paper,COF-5 material is the topic in the research.The behavior of ions and molecules in the pores is investigated with the adsorption energy,the migration energy barrier between the pores and the pores,and the first molecular dynamics simulation and analysis of results.These findings show the liquid-like state in crystallized COF-5 is the key of high ionconduction in this system.The main research method used is first-principles calculations.The research process is based on the experimental papers published,through the rational construction of the model and the first principle method to calculate material stability,adsorption energy,migration energy barrier and particle transport and other properties.The VASP software package and Materials Studio are mainly used in the calculation tool.