Preparation Of Metal Doped Cerium-Titanium Oxide Ion Storage Layer And Its Application In Electrochromic

In recent years,due to serious problems such as energy shortage and environmental pollution,energy-saving electrochromic devices have attracted great interest.Electrochromic devises（ECD）usually called smart window mainly include three parts:electrochromic layer,electrolyte,and ion-storage layer.The ion storage layer is one of the key parts of the electrochromic device.However,compared with the electrochromic layer such as WO₃,the development of the ion storage layer has been slow and there are few related reports.It is particularly important to develop materials with greater ion storage capacity.In this paper,the sol-gel method is used to introduce a certain concentration of metal salt into the precursor of the cerium-titanium sol,and then the ion storage layer for electrochromic devices is obtained by dip-coating method.Through the electrochemical test,visible spectroscopy test,crystality and surface morphology analysis of the ion storage layer,the effect of doped manganese,nickel,zinc,indium on the surface morphology and ion storage capacity of the cerium-titanium oxide film is estimated.The ion storage capacity of manganese dopped cerium-titanium oxide layer is improved.The thin film obtained with the sol doped with 0.1 mol·L^-1 manganese chloride has an ion insertion capacity of 25.91 m C·cm^-2 at 50 cycles,which is higher than 9.07 m C·cm^-2,that is the ion storage capacity of the undoped cerium-titanium oxide layer.But the response time of ion intercalation and deintercalation becomes longer,the layer is dark brown,the visible light transmittance is low,and the number of cycles of ion implantation output is less,and the ion storage capacity is reduced to 6.3 m C·cm^-2 at 1200 cycles.The ion storage capacity of the ion storage layer prepared from the cerium-titanium sol doped with 0.1 mol·L^-1 and 0.2 mol·L^-1 nickel acetate is 5.26 m C·cm^-2 and 4.05 m C·cm^-2,respectively,lower than the ion storage capacity of undoped cerium-titanium oxide layer.This may be because the nickel doped cerium-titanium layer does not perform well in the neutral electrolyte.This paper also studied zinc dopped cerium-titanium oxide layer.When the concentration of precursor zinc acetate is 0.1 mol·L^-1,0.2 mol·L^-1 and 0.3 mol·L^-1,the ion insertion capacity of the ion storage layer was increased by 23%,16.2%,and 19.9%respectively,compared with the undoped cerium-titanium oxide layer.The transmittances of all layers were maintained at about 70%.Cyclic voltammetry test results show that the cyclic reversibility and stability of the film obtained when zinc acetate concentration is 0.1 mol·L^-1is also significantly improved,and the response time of ion intercalation is shortened.The thin film prepared by the cerium-titanium sol doped with 0.15 mol·L^-1 indium nitrate has a good structure due to the proper surface morphology,which significantly improves the ion storage capacity and has good cyclic stability(charge density is15.8 m C·cm^-2 at 100 cycles,15 m C·cm^-2 at 1200 cycles).Transmittance can keep at 69%,and it has a higher peak current in the cyclic voltammetry curve and an excellent diffusion coefficient(10^-10 cm²·s^-1).Finally,indium doped cerium-titanium layer was selected as the ion storage layer,1 mol·L^-1 Li Cl O₄ in propylene carbonate was used as the electrolyte,and commercial WO₃/PET was used as the electrochromic layer to assemble into electrochromic devices.When the ECD is at initial cycle,the optical transmittance is 28%at the colored state and 65%at the bleached state,indicating a difference of 37%in optical transmittance.After 83 cycles,the transmittance has slightly attenuated,but difference in optical transmittance is still acceptable（31.8%）.Compared with electrochromic devices using FTO/glass as the ion storage layer,both the transmittance difference at colored and bleached states and the cycling stability of the ECD are improved.