Preparation And Electrochemical Properties Of Polyethylene Glycol Derivative Based Electrolyte

At present,the lithium ion battery is the main liquid electrolyte for transmitting lithium ion,but the use of liquid electrolyte will make the lithium ion battery with the formation of dendrite during the cycle process,and the growth of the dendrite can cause the diaphragm to be destroyed,causing the short circuit of the battery.Polymer electrolyte is an excellent ionic conductor.It transfers lithium ion through the motion of polymer chain section.It does not exist in the growth of dendrite.At the same time,polymer electrolyte is used as matrix material,and the mechanical properties are excellent.It is an important research direction for the lithium ion battery in the future..In this paper,PMMA-co-PPEGMA based and PEO/PVA based polymer electrolytes were selected as the research objects.Several kinds of nano inorganic materials?SiO2@PPEGMA and GO-g-PEG?with different composition and microstructure were prepared as filler respectively,and polymer electrolyte was prepared by solution casting.The work of this paper is as follows:1.The sol gel method was used to prepare SiO₂ with a size of 100nm.,and then on the surface modified,the prepared SiO₂@PPEGMA nano composite particle dispersion polymerization method;monomer MMA and PEGMA by free radical polymerization method to prepare PMMA-co-PPEGMA copolymer;then blending PMMA-co-PPEGMA,LiClO₄ and SiO₂@PPEGMA.The preparation of solid polymer electrolyte membrane by solution casting method.The research found that the addition of SiO₂@PPEGMA can increase the interface between polymer and inorganic filler,to form a new ion conduction channel,to improve the ionic conductivity of the polymer electrolyte PMMA-co-PPEGMA,when the content of SiO₂@PPEGMA was 6%,the ionic conductivity reaches the maximum,the ionic conductivity at room temperature reached 5.57x10^-5S·cm.^-12.Owing to the graphite oxide surface contains a large number of oxygen groups,Through the chlorination of carboxyl groups on the surface,the carboxyl groups with lower surface activity are changed into active acyl chloride groups.,then the acyl chloride esterification with polyethylene glycol,polyethylene glycol grafted on the surface of the graphite oxide,and then doped in PEO/PVA blends in the preparation of polymer electrolyte by solution casting method.It is found that the addition of PVA can reduce the crystallinity of PEO and increase the ionic conductivity of polymer electrolyte,while the addition of GO-g-PEG can further increase the crystallinity of PEO and enhance the ionic conductivity of polymer electrolyte.When the content of GO-g-PEG reach 3%,the ionic conductivity at room temperature is the optimum,which is 5.5x10^-5S cm^-1.3.Using TPU as the reinforcing material of the polymer matrix,with the PEGMA containing double bonds and EO units as the ligands of lithium ion,then adding the crosslinking agent ethylene glycol Dimethacrylate?EGDMA?,the crosslinking reaction of PEGMA in TPU solution is made under the action of the initiator,and the effect of the addition of different crosslinker on the performance of the polymer electrolyte is studied.It is found that the ionic conductivity of polymer electrolyte can be increased by moderate crosslinking,but excessive crosslinking can make the polymer chain difficult to move.It is lithium ion that can not migrate between polymers chain and lead to a serious decrease in ionic conductivity.