Design And Performance Optimization Of Electrochromic And Energy Storage Bifunctional Devices Based On Zinc Anode

Electrochromic glass is a type of smart glass that can stabilize and change the optical performance reciprocally under the action of external electric field.It has important applications in smart windows,color-changing glasses,anti-glare car rearview mirrors,displays and military camouflage.From the perspective of electrochemical principle and device structure,electrochromic devices not only have device structures similar to energy storage such as batteries and supercapacitors,but have similar processes of charge transfer,storage and element valence change.Therefore,a multifunctional device with energy storage and electrochromic functions can be developed,through reasonable material and mechanism design,and electric energy storage and electrochromic functions can be realized at the same time.In this paper,Prussian blue(PB)and cesium tungsten bronze(Cs_xWO₃)materials are used.The design and performance control mechanism of the ectrochromic-energy etorage device based on zinc anode are explored.Furthermore,the light modulation amplitude,cycle life,energy storage capacity,coloring efficiency and response speed of the device are optimized.The specific research content and results of the paper are as follows:(1)Preparation and performance of Prussian blue/zinc electrochromic and energy storage dual-function devices are researched.A Prussian blue electrochromic layer was uniformly deposited on the surface of FTO(fluorine-doped tin oxide,Sn O₂:F)conductive glass as a electrochromic electrode by hydrothermal method.The zinc metal acts as a counter electrode to balance the charge of the electrochromic electrode.And Zn²⁺/K⁺dual ion electrolyte is connected in series with positive and negative electrodes to build a dual-function device for electrochromism and energy storage.During the discharge(bleaching)process,K⁺and e^-co-insertion reactions occur in the PB film.At the same time,Zn is lost electrons and converted into Zn²⁺into the electrolyte to compensate for K⁺consumption.During the charging(coloring)process,the positive and negative electrodes react in reverse to achieve a revers ible color change.By adjusting the ratio of Zn²⁺/K⁺ions in the electrolyte,the effect of the two ions on the device performance was explored.Spectrophotometer,electrochemical workstation,and battery tester are used to test the performance of the device.Experiments show that low Zn²⁺concentration has better cycle stability.When Zn²⁺/K⁺aquals 1:9,the electrochromic color changes and energy storage device achieves a higher average output voltage(1.24 V),a larger area capacity(78.9 m Ah m^-2),a quick response time Tbleaching=4.1 s,Tcoloring=4.6 s)and long cycle life(7000cycles).At the same time,the device maintains excellent electrochromic performance(transmission modulation amplitude at 633 nm>80%,coloring efficiency=76.8 cm² C^-1).(2)Preparation and performance of cesium tungsten bronze/zinc electrochromic and energy storage dual-function devices.Preparation of tungsten bronze nano-dispersions with different cesium contents.By adding ITO powder(tin-doped indium oxide,In₂O₃:Sn)with a mass ratio of ITO/Cs_xWO₃=20%to the dispersion,the conductivity of the coating is improved.In addition,the solution coating method is used to coat the ITO conductive glass surface.The electrochromic and energy storage dual-function device was constructed by using tungsten bronze doped with different cesium content as the positive electrode and metallic zinc as the negative electrode in Zn²⁺/Al³⁺dual ion electrolyte to take into account the positive and negative electrode reactions.The performance of the device is tested by using a spectrophotometer,electrochemical workstation and battery tester.The electrochromic and energy storage dual-function device achieves a larger area capacity(118 m Ah/m²),a higher cycle life(the capacity remains 62.1%after 200 cycles)and a higher light modulation amplitude(at 633 nm 42.1%change in light transmittance).In addition,the performance of the device is optimal when the cesium doping is0.16.