Preparation And Performance Study Of Quasi-solid Electrolyte Based On Electrolyte And Ordered Mesoporous Silica

The solid electrolyte battery is more suitable for future battery development because it has better safety performance than the liquid electrolyte.However,most solid electrolytes have too low energy density due to their low ionic conductivity and high interfacial resistance.Ordered mesoporous silica（MCM-41）has a moderately sized pore size（2-5 nm）,a high specific surface area（up to 1000 m2/g）and its regular hexagonal channel structure.When preparing composite solid electrolytes conducive to the fixation of the electrolyte and the transmission of ions.In order to solve the above problems of solid electrolytes,a series of composite quasi-solid electrolytes based on electrolyte and ordered mesoporous silica（MCM-41）were designed and optimized by composition optimization.A series of studies and experiments show that the electrolyte has both high safety and high electrochemical performance.The main research contents and results are as follows:（1）Designed and prepared a mixed electrolyte of ethylene carbonate（EC）,dimethyl carbonate（DMC）and lithium bis（trifluoromethanesulfonyl）imide（LiTFSI）,prepared by composite ordered mesoporous material MCM-41 quasi-solid electrolyte,referred to as OS-MCM electrolyte.The electrochemical performances of electrolytes with different lithium salt concentrations on the electrolyte were investigated,and the electrochemical performances of the electrolytes when applied to lithium ion batteries were determined.The results show that after optimization,the electrochemical window of the OS-MCM electrolyte prepared by the electrolyte with a lithium salt concentration of 1 mol/L can reach 5.15 V,and the room temperature conductivity of the electrolyte can reach 1.02×10^-33 S/cm².Electrochemical performance,the cycle can reach more than 2,000 cycles,and the charge and discharge capacity can maintain more than 80%compared with the initial.（2）Design and synthesis of an ionic liquid electrolyte prepared from lithium bis（trifluoromethylsulfonyl）imide（Li TFSI）and ionic liquid bis（trifluoromethylsulfonyl）imide salt（EMIMTFSI）,in an orderly manner The quasi-solid electrolyte prepared by the porous material MCM-41 is referred as IL-MCM.The electrochemical performances of electrolytes with different lithium salt concentrations on the electrolyte were investigated,and the electrochemical performances of the electrolytes when applied to lithium ion batteries were determined.The results show that after optimization,the electrochemical window for the preparation of IL-MCM electrolyte with an electrolyte with a lithium salt concentration of1.25 mol/L reaches 5.5 V,and the room-temperature conductivity of the electrolyte reaches6.78×10^-4S/cm².The electrochemical performance can reach more than 1000 cycles,and the charge and discharge capacity can maintain more than 85%compared with the initial.（3）The ordered mesoporous material MCM-41 and lithium salt bis（trifluoro omethylsulfonyl）imide（LiTFSI）and ionic liquid bis（trifluoromethylsulfonyl）imide salt（EMIMTFSI）were prepared)Based on the prepared IL-MCM electrolyte,an electrolyte prepared by blending it with polyvinylidene fluoride-hexafluoropropylene（PVDF-HFP）,referred as PIL-MCM.The electrochemical performances of electrolytes with different masses of PVDF-HFP were investigated,and the electrochemical performances of the electrolytes were measured when applied to lithium ion batteries.The results show that PIL-MCM electrolyte prepared by adding 1 g of PVDF-HFP to 2.5 g of IL-MCM electrolyte has the best performance,with an electrochemical window of 5.1 V and electrolyte room temperature conductivity of 1.03×10^-3 S/cm².The battery shows Good electrochemical performance,the cycle can reach more than 500 cycles,and the charge and discharge capacity can maintain more than 80%compared with the initial.