Preparation And Performance Optimization Of Epoxy Resin Based All Solid State Polymer Electrolyte On High Temperature Resistant

The current commercial liquid electrolytes maybe not only leak,but also burn and explode as the temperature rises,which can bring great safety hazards to human life.In addition,the organic solvent of the electrolyte makes it incompatible with high specific energy electrode,resulting that the energy density seriously reduces.Then,all-solid-state polymer electrolytes instead of organic liquid electrolytes,which is one of important strategies for the development of lithium batteries in the future.The inorganic solid electrolyte has poor interface performance,which not only easily generates lithium dendrites,but also affects the cycling performance of the battery.The all-solid-state polymer electrolyte has the advantages of light weight,high strength,low price,high designability,mass production and high safety.Therefore,the polymer matrix should be crosslinked in order to form a flexible network structure,which can improve its thermal and mechanical stability,and also improve its electrochemical and interface performance.In this paper,the thermosetting glycidyl ether type epoxy resin,polyethylene glycol diglycidyl ether(PEGDGE)and polyetheramine with molecular weights of 300 and 900(D300 and D900)crosslinked and cured as a main structure by the structure design.An epoxy resin-based all-solid-state polymer electrolyte(ASSPE),that owns lots of advantages,such as high temperature resistance,no impurities,simple preparation process and multiple comprehensive properties,is prepared sucessfully.First of all,the thermosetting epoxy resin PEGDGE was choosed as the polymer matrix.Then we determined that PEGDGE and D900 composed the best flexible network structure system.And Bistrifluoromethane Lithium sulfonimide(LiTFSI)was selected as the best lithium salt.When its content is 40%,the ionic conductivity reaches 1.12×10-5 S/cm;the electrochemical window of ASSPE with different lithium salt contents are similar,around 4.7 V;lithium ion migration number is about 0.12;Young's modulus is 0.69 Mpa.When the lithium salt content is 20%,the maximum tensile strength is 0.58 MPa.The ASSPE film can withstand more than 320?,and its thermal stability can reach 1.53×10-3 S/cm at 170?.But the poor solid-solid interface contact between ASSPE and.electrodes causes disappointed interface performance,thereby affecting the cycling and rate performance of the battery.Therefore,an in-situ preparation method was introduced,and improved the ionic conductivity.The closer the temperature is near room temperature,the higher the ionic conductivity we get.This research shows the formation of SEI layer by the reaction of asspe with electrode effectively inhibits the growth of lithium dendrite.At the current density of 0.1 mA/cm2,lithium is stably deposited and peeled within 700 hours at room temperature,and there is no short-circuit phenomenon appearing within 1000 hours.And at 170?,the Li symmetrical cell can also be cycled stably for more than 450 hours.