Method for regulating energy storage and electrochromic performance of iron-cobalt-nickel prussian blue analogues

Abstract

The application discloses a method for regulating energy storage and electrochromic performance of iron-cobalt-nickel Prussian blue analogues. 2+ And the molar ratio of Ni 2+ In (1) is adjusted.(2) K3[Fe(CN)6] solution is added dropwise into the CoCl2 and NiCl2 mixed solution prepared in step (1), and the reaction is stirred by magnetic force.(3) After the reaction is completed, centrifugal separation, washing and freeze-drying to constant weight are carried out, and iron-cobalt-nickel Prussian blue analogues with different energy storage and color changing performances are obtained.The method can easily realize effective regulation of energy storage (redox potential and capacity) and electrochromic performance (color) of iron-cobalt-nickel Prussian blue analogues by simply adjusting the molar ratio of Co 2+ And Ni 2+ .

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage and electrochromic bifunctional materials, and particularly relates to a method for regulating and controlling energy storage and electrochromic performance of iron-cobalt-nickel Prussian blue analogs. BACKGROUND

[0002] Electrochromic energy storage integrated devices integrate the functions of electrochromic and energy storage, and have wide application prospects in the fields of energy-saving intelligent windows, energy storage, energy-saving displays, military camouflage, etc. In recent years, they have attracted great attention. However, due to the influence of low specific capacity, slow reaction kinetics, poor stability and single color change, it is still a major challenge to develop and design high-performance electrochromic energy storage integrated devices. At present, electrochemical energy storage devices represented by lithium ion batteries have been widely used, and single-function electrochromic devices have also been widely reported and partially commercialized. However, the research on electrode materials and devices with electrochromic energy storage dual functions is still in its infancy. Although there have been some reports on electrochromic energy storage integrated devices, their electrochromic performance or energy storage performance is far from that of single-function electrochromic devices or energy storage devices, and the color change of the devices is relatively single. Prussian blue analogs have an open framework structure, large specific surface area, uniform metal active sites and adjustable composition, and show great application potential in the fields of electrochemical energy storage and electrochromism. Therefore, the application synthesizes iron-cobalt-nickel Prussian blue analogs with energy storage and color change dual functions by a simple chemical co-precipitation method, and easily realizes effective regulation of their energy storage and color change performance by a method of simply adjusting the molar ratio of Co 2+ and Ni 2+ in the preparation process. SUMMARY

[0003] The purpose of the application is to provide a method for regulating and controlling the energy storage and electrochromic performance of iron-cobalt-nickel Prussian blue analogs.

[0004] The specific steps are as follows:

[0005] (1) configuring a mixed solution of CoCl2 and NiCl2, adjusting the molar ratio of Co 2+ and Ni 2+ in the mixed solution to 0:1~3:1 or the molar ratio of Ni 2+ and Co 2+ to 0:1~3:1, and making the total molar concentration of Co 2+ and Ni 2+ in the mixed solution 0.01 mol / L.

[0006] (2) 200 mL of 0.01 mol / L K3[Fe(CN)6] solution is added dropwise into 200 mL of the CoCl2 and NiCl2 mixed solution prepared in step (1), and the reaction is stirred magnetically for 1 hour.

[0007] (3) After the reaction is completed, centrifugal separation is performed, and the precipitate is washed with deionized water for 3 times, and then freeze-dried to constant weight, so that the iron cobalt nickel Prussian blue analogs with different energy storage and color change performances are obtained, thereby realizing the regulation of the energy storage and electrochromic performance of the iron cobalt nickel Prussian blue analogs.

[0008] The CoCl2 and NiCl2 mixed solution in step (1) is an aqueous solution of CoCl2·6H2O and NiCl2·6H2O.

[0009] The method has the advantages and significance that the energy storage (redox potential, capacity) and electrochromic performance (color) of the iron cobalt nickel Prussian blue analogs are easily regulated by simply adjusting the molar ratio of Co 2+ and Ni 2+ during preparation. The application content has certain theoretical and practical guiding significance for the design, preparation and performance optimization of new energy storage / electrochromic dual functional materials and devices. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 XRD patterns of the Prussian blue analogs prepared in examples 1-5 of the application.

[0011] Figure 2 CV curves of the Prussian blue analogs prepared in examples 1-5 of the application.

[0012] Figure 3 Cycle performance curves of the Prussian blue analogs prepared in examples 1-5 of the application at 4A.g -1 current density.

[0013] Figure 4 Color change diagrams of the Prussian blue analog thin films prepared in examples 1-5 of the application in the oxidized state and the reduced state.

[0014] Figure 5 Transmission spectra of the Prussian blue analog thin film prepared in example 1 of the application in the oxidized state and the reduced state.

[0015] Figure 6 Transmission spectra of the Prussian blue analog thin film prepared in example 2 of the application in the oxidized state and the reduced state.

[0016] Figure 7This is the transmittance spectra of the Prussian blue analog film prepared in Example 3 of the present invention in the oxidized and reduced states.

[0017] Figure 8 This is the transmittance spectra of the Prussian blue analog film prepared in Example 4 of the present invention in the oxidized and reduced states.

[0018] Figure 9 This is the transmittance spectra of the Prussian blue analog film prepared in Example 5 of the present invention in the oxidized and reduced states. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to specific embodiments. It should be noted that the following embodiments are intended to help those skilled in the art better understand the present invention, rather than to limit the scope of protection of the present invention. Those skilled in the art may make some non-essential improvements and adjustments based on the above content.

[0020] Example 1:

[0021] (1) Prepare CoCl2 solution so that Co 2+ The molar concentration is 0.01 mol / L.

[0022] (2) Add 200 mL of 0.01 mol / L K3[Fe(CN)6] solution dropwise to 200 mL of the CoCl2 solution prepared in step (1) and stir magnetically for 1 hour.

[0023] (3) After the reaction, the product was centrifuged and washed three times with deionized water. The precipitate was then freeze-dried to a constant weight to obtain the Prussian blue analogue, cobalt ferrocyanide (CoHCF).

[0024] Example 2:

[0025] (1) Prepare a mixed solution of CoCl2 and NiCl2, and adjust the content of Co in the mixed solution. 2+ and Ni 2+ The molar ratio of Co in the mixed solution is 3:1. 2+ and Ni 2+ The total molar concentration is 0.01 mol / L.

[0026] (2) Add 200 mL of 0.01 mol / L K3[Fe(CN)6] solution dropwise to 200 mL of the mixed solution of CoCl2 and NiCl2 prepared in step (1) and stir magnetically for 1 hour.

[0027] (3) After the reaction, the mixture was centrifuged and washed three times with deionized water. The precipitate was then freeze-dried to a constant weight to obtain the Prussian blue analogue, cobalt nickel ferrocyanide (CoNiHCF) (3:1).

[0028] Example 3:

[0029] (1) Prepare a mixed solution of CoCl2 and NiCl2, and adjust the content of Co in the mixed solution. 2+ and Ni 2+ The molar ratio of Co in the mixed solution is 1:1. 2+ and Ni 2+ The total molar concentration is 0.01 mol / L.

[0030] (2) Add 200 mL of 0.01 mol / L K3[Fe(CN)6] solution dropwise to 200 mL of the mixed solution of CoCl2 and NiCl2 prepared in step (1) and stir magnetically for 1 hour.

[0031] (3) After the reaction, the mixture was centrifuged and washed three times with deionized water. The precipitate was then freeze-dried to a constant weight to obtain the Prussian blue analogue, cobalt nickel ferrocyanide (CoNiHCF) (1:1).

[0032] Example 4:

[0033] (1) Prepare a mixed solution of CoCl2 and NiCl2, and adjust the content of Co in the mixed solution. 2+ and Ni 2+ The molar ratio of Co in the mixed solution is 1:3. 2+ and Ni 2+ The total molar concentration is 0.01 mol / L.

[0034] (2) Add 200 mL of 0.01 mol / L K3[Fe(CN)6] solution dropwise to 200 mL of the mixed solution of CoCl2 and NiCl2 prepared in step (1) and stir magnetically for 1 hour.

[0035] (3) After the reaction, the mixture was centrifuged and washed three times with deionized water. The precipitate was then freeze-dried to a constant weight to obtain the Prussian blue analogue, cobalt nickel ferrocyanide (CoNiHCF) (1:3).

[0036] Example 5:

[0037] (1) Prepare NiCl2 solution so that Ni 2+ The molar concentration is 0.01 mol / L.

[0038] (2) Add 200 mL of 0.01 mol / L K3[Fe(CN)6] solution dropwise to 200 mL of NiCl2 solution prepared in step (1) and stir magnetically for 1 hour.

[0039] (3) After the reaction, the product was centrifuged and washed three times with deionized water. The precipitate was then freeze-dried to a constant weight to obtain the Prussian blue analogue, nickel ferrocyanide (NiHCF).

[0040] Application example: (1) Preparation of thin film. Weigh 0.05 g of the Prussian blue analogue prepared in Examples 1 to 5, add 1 mL of distilled water to it and ultrasonicate for 1 hour, then stir evenly under magnetic stirring, then add 100 µL of PEDOT:PSS and continue stirring for several hours to obtain a spin coating solution. Spin coat the solution on an ITO substrate (cut into 1×2 cm) at 2500 rpm for 20 seconds, dry it at 80°C for 5 minutes after spin coating once, and repeat the spin coating four times. The spin-coated film is annealed at 120°C for 10 minutes at a heating rate of 1°C / min in a muffle furnace to obtain a Prussian blue analogue film. (2) Energy storage and electrochromic performance test. The prepared Prussian blue analogue film is assembled into a three-electrode system in 1 M LiClO4 / PC electrolyte, with the working electrode being the Prussian blue analogue film (test area 1×1 cm 2 ), the counter electrode is platinum, and the reference electrode is Ag / Ag + The electrochemical performance was tested using a CHI660E electrochemical workstation manufactured by Shanghai Chenhua Instrument Co., Ltd. The cyclic voltammetry (CV) potential window was set at -0.7 to 0.7 V, and the scan rate was 20 mV / s. Chronopotentiometry (CP) was used at 4 A·g -1 The Prussian blue analog film was subjected to a long cycle test of 500 cycles at a current density of -0.7 to 0.7 V. The transmittance spectrum of the Prussian blue analog film was measured in the wavelength range of 350 to 800 nm using a Lambda 750 UV-visible-near-infrared spectrophotometer produced by Perkin Elmer.

[0041] from Figure 1 It can be seen that the materials prepared in Examples 1 to 5 are all Prussian blue analogs.

[0042] from Figure 2 As can be seen, the Prussian blue analogs prepared in Examples 1 to 5 all have a distinct oxidation peak and a distinct reduction peak. Comparison shows that as the Ni content in the material increases, the redox peak area of ​​the thin film electrode gradually increases and the redox potential gradually decreases; while as the Co content increases, the redox peak area of ​​the thin film electrode gradually decreases and the redox potential gradually increases.

[0043] from Figure 3 It can be seen that the Prussian blue analogs prepared in Examples 1 to 5 all have good cycle stability. By comparison, it can be seen that with the increase of Ni content in the material, the specific capacity of the thin film electrode gradually increases, while with the increase of Co content, the specific capacity of the thin film electrode gradually decreases.

[0044] comprehensive Figure 2 and Figure 3 The results show that by changing the ratio of Co and Ni in the Prussian blue analogue, the redox potential and lithium storage capacity of the material can be directional controlled.

[0045] from Figure 4 As can be seen, the Prussian blue analogs prepared in Examples 1-5 exhibit different colors in both the oxidized and reduced states. As the Ni content in the samples increases or the Co content decreases, the color of the films in the oxidized state gradually changes from purple-red to orange and then to yellow, while the color of the films in the reduced state gradually changes from green to colorless. This demonstrates that by varying the Co:Ni ratio in the Prussian blue analog, the color of the material in both the oxidized and reduced states can be effectively manipulated.

[0046] from Figure 5-9 As can be seen from the graph, the transmittance spectra of the Prussian blue analogs prepared in Examples 1 to 5 changed in both the oxidized and reduced states. This further demonstrates that the electrochromic behavior of the Prussian blue analogs can be regulated by changing the ratio of Co to Ni.

Claims

1. A method for regulating the energy storage and electrochromic properties of an iron-cobalt-nickel Prussian blue analogue, characterized in that The specific steps are: (1) Prepare a mixed solution of CoCl2 and NiCl2, and adjust the content of Co in the mixed solution. 2+ and Ni 2+ The molar ratio is 0:1~3:1 or Ni 2+ and Co 2+ The molar ratio of Co in the mixed solution is 0:1~3:1, and the 2+ and Ni 2+ The total molar concentration is 0.01 mol / L; (2) Add 200 mL of 0.01 mol / L K3[Fe(CN)6] solution dropwise to 200 mL of the mixed solution of CoCl2 and NiCl2 prepared in step (1) and stir magnetically for 1 hour; (3) After the reaction is completed, the mixture is centrifuged and washed three times with deionized water. The precipitate is then freeze-dried to a constant weight to obtain Fe-Co-Nickel Prussian blue analogues with very different energy storage and electrochromic properties, thereby achieving the regulation of the energy storage and electrochromic properties of Fe-Co-Nickel Prussian blue analogues.

2. The method for regulating the energy storage and electrochromic properties of an iron-cobalt-nickel Prussian blue analogue according to claim 1, characterized in that: The mixed solution of CoCl2 and NiCl2 in step (1) is an aqueous solution of CoCl2·6H2O and NiCl2·6H2O.

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