Preparation And Characterization Of Gel Electrolytes For Electrochromic Devices

Increasing the energy efficiency of buildings is a key way to facilitate the transition to an energy-based economy based on renewable energy.Electrochromic smart window can change the visible and infrared light transmittance to adjust the indoor temperature and to achieve dynamic adjustment of indoor lighting,therefore it can reduce the building energy consumption significantly.In electrochromic devices,electrolyte is the most imperative component which can be used to conduct ions between two electrodes.In this paper,the main research object is the gel electrolyte for electrochromic device,which was prepared by adding polymer matrix,ionic liquid and inorganic nanoparticles in liquid electrolyte.And the electrochromic properties of the electrochromic devices that consist by gel electrolyte and electrochromic film were investigated.?1?Preparation of PMMA based gel electrolyte: Adding the PMMA?polymethyl methacrylate?as polymer matrix in 1mol/L Li Cl O4/PC?lithium perchlorate/propylene carbonate?solution,the gel polymer electrolyte can solve the sealing problems.The study found that the ionic conductivity of the PMMA based gel electrolyte was found to be 1.8×10-3 S/cm when the mass fraction was 10 wt%.When the WO₃ films that prepared by sputtering and hydrothermal methods assembled into electrochromic device with gel electrolyte,the optical modulation range of the devices was 23% and 13%,respectively,and the response times were 86.8 s/99.1 s,59.8 s/53.3 s,the efficiency was 34.1 cm2/C,30.0 cm2/C,which has good electrochromism properties.?2?Preparation of PMMA-[Emim]BF₄ composite gel electrolyte: PMMA-[Emim]BF₄ composite gel electrolyte was prepared by adding [Emim]BF₄ in the PMMA based gel electrolyte.The addition of [Emim]BF₄ increased the concentration of active particles in the system and increased the ion diffusion ion diffusion performance.When the mass fraction was 10 wt%,the ionic conductivity was 2.9×10-3 S/cm,and has increase of 60%.When the electrochromic devices were fabricated by sputtering and hydrothermal methods,the optical modulation range of the devices was 27% and 51%,respectively,the response times were 71.2 s/52.8 s,72.1 s/17.1 s,and the efficiency is 59.4 cm2/C,35.7 cm2/C,respectively,and the electrochromic device can complete the coloring / fading electrochromic device with small applied voltage,and the overall performance is greatly improved.?3?Preparation of Inorganic nanoparticle composite gel electrolyte: Inorganic nanoparticle composite gel electrolyte was prepared by adding inorganic nanoparticle-fumed Si O2 to the PMMA based electrolyte and the PMMA-[Emim]BF₄ composite gel electrolyte,respectively.And the ionic conductivity reached to 2.6×10-3 S/cm and 4.0×10-3 S/cm when the mass fraction of fumed Si O2 was 4 wt%.The stability and mechanical properties of the electrolyte has improved,and have good dispersibility.When the WO₃ films that prepared by sputtering and hydrothermal methods assembled into electrochromic device with two kings of gel electrolyte,the range of optical modulation was increased by 30% and 15%,the response time had shorten effectively,and the coloring efficiency of the devices were improved by 20% and 32%,respectively,while the device stability was enhanced effectively.