Preparation And Property Of Epoxy Solid Electrolytes

Solid Electrolytes have many excellent properties:good film formation,light weight,no liquid leakage,non-combustibility,good viscoelasticity and high safety.Moreover,the research of such materials is also helpful in the research of complex solvent-containing polyelectrolytes and ion transport mechanisms in biofilms.Therefore,the research of solid electrolytes is of great significance both in terms of theoretical needs and practical applications.The research goal of this paper is to prepare a solid electrolyte with excellent mechanical properties,good processing performance,high electrochemical stability and high electrical conductivity.Three ionic liquids were synthesized prior to the preparation of the solid electrolyte:1-aminoethyl-3-methylimidazolium bromide（C₂NH₂MImBr）,1-propyl-3-methylimidazoliumbromide（PMImBr）and1-propyl3-methylimidazolium bis（trifluoromethanesulfonyl）imide salt（PMIm-TFSI）.The effects of temperature changes of these ionic liquids on electrical conductivity and electrochemical stability and their changes were investigated.At room temperature,PMIm-TFSI has the highest conductivity and the electrochemical stability window is the widest.The solid electrolyte was prepared by adding the above ionic liquid with epoxy resin as the matrix,and the relationship between the performance of the solid electrolyte and the type of the ionic liquid,content of the ionic liquid,lithium salt content and temperature was studied.For the Br^-containing liquids,it was found through mechanical property test and conductivity test that the solid electrolyte with PMImBr was better than the solid electrolyte with C₂NH₂MImBr in the same ionic liquid content.The thermogravimetric test showed that the thermal stability of the solid electrolyte with C₂NH₂MImBr was better than that of the solid electrolyte with PMImBr,but the thermal decomposition temperature was high,which did not affect the daily use of the electrolyte.From the previous studies,it was found that the conductivity of C₂NH₂MImBr and PMImBr is lower than that of PMIm-TFSI.It is concluded that the conductivity of the solid electrolyte should be as follows when the ionic liquid is added to the epoxy resin to prepare the solid electrolyte.On the basis of the above,further research proves that when 17 mass%of lithium salt is added,the conductivity and tensile strength of the PMIm-TFSI solid electrolyte added are better than those of the solid electrolyte with PMImBr,and the elongation at break is reversed.Continue to study the effect of lithium salt content on the conductivity of solid electrolytes,and based on the purpose of preparing a solid electrolyte with balanced mechanical properties and conductivity properties,the PMIm-TFSI content of 60 mass%,and the lithium salt content of 10 mass%are the optimal ratio of solid electrolyte,and based on this,multi-walled carbon nanotubes（MWCNTs）are added to further improve the performance of the solid electrolyte.The test results show that when the content of MWCNTs is 0.5 mass%,it can have the highest conductivity,the highest capacity,the highest elongation at break and the higher tensile st rength.Therefore,the subject finally determined that the best ratio of solid electrolyte is:PMIm-TFSI content of 60 mass%,lithium salt content of 10 mass%and MWCNTs content of 0.5mass%.