Preparation And Performance Research Of Epoxy Resin/Succinonitrile Solid Polymer Electrolyte

Lithium metal batteries with higher energy density can be obtained by replacing traditional graphite electrodes with lithium metal anode materials,but there are problems such as the lithium dendrite growth and electrode passivation that damage electrochemical and safety performance.Due to its excellent intrinsic polymer properties,the solid polymer electrolyte can be specifically designed to balance the flexibility of the polymer chain segments and the overall mechanical strength of the material required for lithium-ion transmission,effectively improve the interfacial problems inside the battery,build stable lithium-ion fast transmission channels,and inhibit the growth of lithium dendrites.At the same time,specific functional electrolytes suitable for different use requirements can be obtained through reasonable material selection and structural design for special functional batteries.In this work,flexible epoxy resin poly（ethylene glycol）diglycidyl ether（PEGDGE）was selected as the polymer matrix of the solid electrolyte.The flexible chain crosslinking network containing a large number of ether oxygen bonds was prepared by epoxy-amine curing reaction.The plastic crystal succinonitrile（SN）was compounded with epoxy resin matrix by in-situ method and the ratio was adjusted.The epoxy resin-based solid electrolyte with high electrochemical performance and excellent interfacial contact with three-dimensional continuous ionic phase was designed.Secondly,a crosslinked polymer electrolyte with flame retardant properties was designed by introducing hexachlorocyclotriphosphazene（HCCP）to react with the polymer matrix,and a flame retardant solid electrolyte with excellent electrochemical properties was obtained.Firstly,the effect of SN contents on the mechanical,ionic conductivity and other properties of the epoxy resin electrolyte was investigated.The PDSN-5:5with the best performance was selected as the follow-up study,which has a dense micro-surface structure and a tensile strength of 0.13 MPa.The ionic conductivity of the solid electrolyte is 8.60×10^-4S cm^-1 at 25℃,and the electrochemical window is 5.5 V.The lithium-ion migration number is 0.47.It can maintain a low polarization voltage of 37 m V at a current density of 0.1 m A cm^-2for 1200 h,and the assembled full-cell adapted LFP/NCM cathode also exhibits excellent cycle stability（LFP‖PDSN-5:5‖Li battery after 100 cycles at0.1 C,the capacity retention rate is 96.4%;after 100 cycles at 0.1 C,the capacity retention rate of NCM‖PDSN-5:5‖Li battery is 77.6%）.Secondly,in order to improve the safety performance of batteries,a cross-linked polymer electrolyte with flame retardant properties was obtained by the reaction of HCCP with polyetheramine.The electrolyte showed excellent flame retardant self-extinguishing ability in the combustion experiment.The ionic conductivity of the prepared electrolyte is 7.28×10^-4S cm^-1,the lithium ion migration number is 0.33,and the electrochemical stability window is 4.7 V at room temperature.After 500 h of cycling at a current density of 0.1 m A cm^-2,a stable overpotential is maintained.It exhibited good cycle stability in the full battery（the capacity retention rate of LFP‖HDSN-2:3‖Li battery is 65.8%after100 cycles at 0.1 C）.This flame retardant cross-linked polymer electrolyte shows a potential application for special functional batteries.