Preparation Of Polymer-based Electrolyte And Its Application In Electrochromism

The phenomenon that the appearance color and optical properties of coloring materials can be cyclically changed due to the application of different bias voltages is called electrochromism(EC).The controllable optical characteristics of electrochromic(EC)materials have caused electrochromic devices(ECD)to attract widespread attention from academics.They are widely used in intelligent color-changing windows,displays,and automotive anti-glare rearview mirrors.The traditional ECD is a sandwich-like structure composed of an electrochromic layer,an electrolyte layer,and an ion storage layer sandwiched between conductive glass or a conductive film.The performance of the electrolyte greatly affects the discoloration of the ECD Performance and cycle stability.So far,the electrolyte used in most electrochromic devices is still liquid.Although the liquid electrolyte has the advantage of high ionic conductivity,its application in ECD is greatly restricted due to its easy leakage and easy to cause the EC layer to fall off.This paper explores the application of electrolytes of two systems,polyvinylidene fluoride-hexafluoropropylene(PVDF-HFP)and polyethylene oxide(PEO),to electrochromic devices.A PVDF-HFP composite gel electrolyte was prepared by a simple immersion precipitation method,and a simple UV-induced light-induced gel electrolyte based on polyethylene glycol(PEG)oligomers containing a large number of PEO segments was prepared.The details are as follows:1.A series of gel electrolytes were prepared by blending PVDF-HFP with additives GFs and pore-forming agent PVP,and adjusting the addition ratio of the two.The purpose is to improve the pore structure and mechanical properties of pure PVDF-HFP membrane.The resulting composite electrolyte has a high ionic conductivity of 3.05×100-3 S·cm-1 and a tensile strength of 4.57 MPa.The assembled ECD can still achieve stable and fast color switching after 50 cycles.2.Polyethylene glycol monomethyl ether acrylate(PEGMA)and polyethylene glycol diacrylate(PEGDA)are used as precursors for the manufacture of polymer electrolyte networks.The polymerization is initiated by ultraviolet light,and the liquid electrolyte is confined in the cross-linked network to avoid the leakage of the liquid electrolyte while ensuring high ionic conductivity.The effects of the mass ratio of mono-bifunctional acrylates,PEG oligomer system(PEGMA+PEGDA)and lithium salt solution(Li-PC)system on the conductivity of polymer electrolytes were studied in detail.When PEGMA/PEGDA is 75/25 and Li-PC/PEG is 75/25,the polymer electrolyte has a high ion conductivity of 1.96×10-3 S·cm-1,and the ECD thus prepared is still after 580 cycles Can achieve stable and fast color switching.3.Using PEGMA to copolymerize with 2-propenylamino-2-methylpropanesulfonic acid(AMPS)and prepare graft copolymer(AP)by anionic polymerization method,the purpose is to introduce sulfonic acid into the system and increase lithium salt Dissolve the amount and destroy the regularity of the chain segment.A-P and PEG were mixed together to explore the effect of A-P content on the electrochemical performance of the system.When the AP/PEGDA is 60/40,the composite polymer electrolyte exhibits a high ionic conductivity of 1.711×10-3 S·cm-1,and the ECD thus prepared can still achieve stable and fast color switching after 400 cycles.At the same time,the study found that the introduction of PVDF-HFP composite porous membrane with good mechanical properties into the above composite electrolyte significantly improves the tensile properties of the electrolyte and has little effect on ionic conductivity.