LONG-RANGE ELECTROCHROMIC FIBER FOR INFRARED CAMOUFLAGE AND PREPARATION METHOD THEREOF

Abstract

A long-range electrochromic fiber for infrared camouflage and preparation method thereof are disclosed. The method includes: coating indium tin oxide dispersion, electrolyte solution, and electrochromic material on the surface of the metal fiber sequentially, and preparing counter electrodes and polymer protective layer on the outside of the electrochromic layer to obtain the long-range electrochromic fiber. The obtained long-range electrochromic fiber can realize the regulation of infrared emissivity, can be continuously prepared for more than 100 meters and has a good application prospect in infrared camouflage, wearable display, etc.

Claims

1. An electrochromic fiber, wherein structures from inside to outside are: a metal fiber inner electrode, an ITO layer, an electrolyte layer, an electrochromic layer, a counter electrode, and a polyethylene protective layer.

2. The electrochromic fiber of claim 1, wherein components of the electrolyte layer comprise: lithium perchlorate (LiClO.sub.4), an organic solvent, an ionic liquid, and polyvinylidene fluoride hexafluoropropylene (PVDF-HFP); wherein an electrochromic material is at least one of poly (3,4-ethylene dioxythiophene) (PEDOT), polyaniline (PANI), and a multilayer graphene.

3. The electrochromic fiber of claim 1, wherein the counter electrode is a metal fiber coated with an ITO coating; wherein the counter electrode is a spiral counter electrode structure and/or a parallel counter electrode structure.

4. The electrochromic fiber of claim 1, wherein a thickness of the electrolyte layer is 60 μm-180 μm, and a thickness of the polyethylene protective layer is 0.1 mm-0.3 mm.

5. A method for preparing an electrochromic fiber, comprising: (1) coating an indium tin oxide (ITO) dispersion, an electrolyte solution, and electrochromic materials on a surface of a metal fiber in turn, and heating and drying successively; (2) coating a polymer protective layer on an outside of an electrochromic layer and placing a counter electrode between the electrochromic layer and the polymer protective layer, to obtain the electrochromic fiber.

6. The method of claim 5, wherein the electrolyte solution in step (1) is: LiClO.sub.4 is dissolved in a mixture of an organic solvent and an ionic liquid, then PVDF-HFP is added to the mixture and stirred evenly to obtain the electrolyte solution; wherein a volume ratio of the organic solvent to the ionic liquid is 9:1-2:3; and a mass ratio of the organic solvent to the PVDF-HFP is 1:0.5-1:1.5.

7. The method of claim 5, wherein the metal fiber in step (1) is pulled by a power transmission device, each layer is coated on the surface of the metal fiber through a solution tank successively, then heated and cured by a heating device; wherein a fiber transmission speed is 1 m/min-5 m/min; wherein a pore diameter of the solution tank is 0.4 mm-1 mm; wherein a heating temperature is 90° C.-140° C.

8. The method of claim 5, wherein in step (2), the counter electrode is spirally wound or attached in parallel to a fiber surface prepared in step (1), and then the polymer protective layer is coated on an outermost layer by an extrusion.

9. A device for preparing an electrochromic fiber, comprising a power transmission device, a solution coating mold, a heating device, a first collection device, a counter electrode introduction device, an extruder, a cooling device, and a second collection device; wherein driven by the power transmission device, metal fibers pass through a solution tank and the heating device in turn and are collected through the first collection device.

10. A method of an application of the electrochromic fiber of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIGS. 1A and 1B are continuous preparation process schemes of long-range electrochromic fiber: FIG. 1A is a multilayer structure preparation scheme of electrochromic fiber; FIG. 1B is a preparation scheme of the counter electrode and protective layer; wherein, 1 is the solution tank, 2 is the heating device, 3 is the collection device, 4 is the counter electrode introduction device, 5 is the extruder and 6 is the cooling device.

[0033] FIG. 2 is a scheme of electrochromic fibers with different structures, wherein, 1 is the metal fiber inner electrode, 2 is the ITO layer, 3 is the electrolyte layer, 4 is the electrochromic layer, 5 is the metal fiber counter electrode coated with ITO, and 6 is the polymer protective layer.

[0034] FIG. 3 is a digital photograph of long-range electrochromic fiber.

[0035] FIG. 4 is infrared reflection spectra of electrochromic fiber before and after the color change.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The invention is further described in combination with specific examples. It should be understood that these examples are only used to illustrate the invention and not to limit the scope of the invention. In addition, it should be understood that after reading the content of the invention, the technicians of this field can make various changes or modifications to the invention, and these equivalent forms also fall within the scope defined by the claims attached to the application.

[0037] The preparation device comprises the power transmission device, solution tank, heating device, first collection device, counter electrode introduction device, extruder, cooling device, and second collection device.

[0038] Driven by the power transmission device, the metal fiber pass through the solution tank and the heating device in turn and is collected through the collection device. The solution tank is filled with ITO dispersion, electrolyte solution, and electrochromic solution respectively, then coated on the surface of metal fiber in turn, and heated and dried successively. The metal fiber counter electrode coated with the ITO layer is wound in parallel or spiral on the surface of the above-prepared fiber, and the polymer protective layer is prepared on the outer layer through the extruder. Finally, electrochromic fiber is collected by the collection device.

[0039] Metal fiber (diameter: 0.1 mm and 0.3 mm. The counter electrode is 0.1 mm. The inner electrode is 0.3 mm), indium tin oxide dispersion and polyethylene (molecular weight: about 200000) are provided by Shanghai Keyan Photoelectric Technology Co., Ltd. Lithium perchlorate (99%) and organic solvents such as propylene carbonate were purchased from Sinopharm Chemical Reagent Co., Ltd. Ionic liquids were purchased from Shanghai Moni Chemical Technology Co., Ltd. Poly (3,4-ethylene dioxythiophene) (brand: F010) was purchased from Shanghai Jingnian Chemical Co., Ltd. Polyaniline (98%) was purchased from Cool Chemical Technology (Beijing) Co., Ltd. and multilayer graphene (1 wt.%) was purchased from Suzhou Yougao Nanomaterials Co., Ltd. Polyvinylidene fluoride hexafluoropropylene (PVDF-HFP, brand: 21216) was purchased from Shenzhen Taotao Plastic Co., Ltd.

[0040] The thickness of the ITO layer is 6-10 μm; the ITO coating on the surface of the metal fiber is 6-10 μm.

Example 1

[0041] The ITO was used as the electrochemical protective layer of the metal electrode, and PEDOT was used as the electrochromic layer.

[0042] The LiClO.sub.4 (1 M) was dissolved in the mixture of PC and [BMIm][BF.sub.4] (volume ratio is 1:1). Then, PVDF-HFP was added to the mixture and stirred evenly to obtain the electrolyte (mass ratio of PVDF-HFP to PC is 1:1).

[0043] ITO dispersion, electrolyte solution, and PEDOT dispersion were successively coated on the surface of metal fiber through the solution tank by using the customized continuous preparation device (FIGS. 1A and 1B), the fiber was collected after high-temperature curing. The thickness of the electrolyte layer was about 120 μm. The pore diameter of the solution tank was 0.69 mm. The fiber transmission speed was 3 m/min. The curing temperature was 110° C.

[0044] The metal fiber coated with ITO was spirally wound on the surface of the above fiber, and the polyethylene protective layer was prepared on the outer layer by extrusion. The thickness of the protective layer was 0.2 mm. Finally, the electrochromic fiber was collected. Under the voltage of −1.5 V, the coloring time of 10 cm long electrochromic fiber is 0.8 s. Under the voltage of 1.5 V, the bleaching time of electrochromic fiber is 0.7 s. In the wavelength range of 2.5-20 μm, the change of infrared reflectance of electrochromic fiber before and after the color change is about 20%.

[0045] FIGS. 1A and 1B are the continuous preparation process schemes of long-range electrochromic fiber: FIG. 1A is a multilayer structure preparation scheme of electrochromic fiber; FIG. 1B is a preparation scheme of the counter electrode and protective layer. FIG. 2 is the scheme of electrochromic fibers with different structures. FIG. 3 is the digital photograph of long-range electrochromic fiber. FIG. 4 is the infrared reflection spectra of electrochromic fiber before and after the color change.

Example 2

[0046] The ITO was used as the electrochemical protective layer of the metal electrode, and PEDOT was used as the electrochromic layer.

[0047] The LiClO.sub.4 (1 M) was dissolved in the mixture of PC and [BMIm][BF.sub.4] (volume ratio is 1:1). Then, PVDF-HFP was added to the mixture and stirred evenly to obtain the electrolyte (mass ratio of PVDF-HFP to PC is 1:1).

[0048] ITO dispersion, electrolyte solution, and PEDOT dispersion were successively coated on the surface of metal fiber through the solution tank by using the customized continuous preparation device (FIGS. 1A and 1B), the fiber was collected after high-temperature curing. The thickness of the electrolyte layer was about 120 μm. The pore diameter of the solution tank was 0.69 mm. The fiber transmission speed was 3 m/min. The curing temperature was 110° C.

[0049] The metal fiber coated with ITO was spirally wound on the surface of the above fiber, and the polyethylene protective layer was prepared on the outer layer by extrusion. The thickness of the protective layer was 0.2 mm. Finally, the electrochromic fiber was collected. The electrochromic fiber was colored under the voltage of −0.9 V and bleached under the voltage of 0.9 V.

[0050] Since the voltage applied to the electrochromic fiber was reduced, which reduced the doping degree of ions in the electrolyte to the electrochromic material, resulting in the change of infrared reflectance before and after fiber color change being lower than that in example 1. The change of infrared reflectance of electrochromic fiber before and after the color change was about 10%.

Example 3

[0051] The ITO was used as the electrochemical protective layer of the metal electrode, and PEDOT was used as the electrochromic layer.

[0052] The LiClO.sub.4 (1 M) was dissolved in the mixture of PC and [BMIm][BF.sub.4] (volume ratio is 1:1). Then, PVDF-HFP was added to the mixture and stirred evenly to obtain the electrolyte (mass ratio of PVDF-HFP to PC is 0.5:1).

[0053] ITO dispersion, electrolyte solution, and PEDOT dispersion were successively coated on the surface of metal fiber through the solution tank by using the customized continuous preparation device (FIGS. 1A and 1B), the fiber was collected after high-temperature curing. The thickness of the electrolyte layer was about 60 μm. The pore diameter of the solution tank was 0.69 mm. The fiber transmission speed was 5 m/min. The curing temperature was 90° C.

[0054] The metal fiber coated with ITO was spirally wound on the surface of the above fiber, and the polyethylene protective layer was prepared on the outer layer by extrusion. The thickness of the protective layer was 0.2 mm. Finally, the electrochromic fiber was collected.

[0055] The solubility of PVDF-HFP in the electrolyte was reduced due to the decrease of PVDF-HFP content, the increase in transmission speed, and the decrease in curing temperature, and the electrolyte strength is lower than that in example 1.

Example 4

[0056] The ITO was used as the electrochemical protective layer of the metal electrode, and PEDOT was used as the electrochromic layer. The LiClO.sub.4 (1 M) was dissolved in the mixture of PC and [BMIm][BF.sub.4] (volume ratio is 4:1). Then, PVDF-HFP was added to the mixture and stirred evenly to obtain the electrolyte (mass ratio of PVDF-HFP to PC is 1.5:1).

[0057] ITO dispersion, electrolyte solution, and PEDOT dispersion were successively coated on the surface of metal fiber through the solution tank by using the customized continuous preparation device (FIGS. 1A and 1B), the fiber was collected after high-temperature curing. The thickness of the electrolyte layer was about 120 μm. The pore diameter of the solution tank was 0.69 mm. The fiber transmission speed was 1 m/min. The curing temperature was 140° C.

[0058] The metal fiber coated with ITO was spirally wound on the surface of the above fiber, and the polyethylene protective layer was prepared on the outer layer by extrusion. The thickness of the protective layer was 0.2 mm. Finally, the electrochromic fiber was collected.

[0059] Due to the increase of PVDF-HFP content and the decrease of ionic liquid content in the electrolyte, hindered the diffusion of ions in the electrolyte, resulting in the decrease in ionic conductivity. In addition, the increase in the curing temperature of the electrolyte promoted solvent volatilization, which also reduced the ionic conductivity of the electrolyte. Therefore, the switching time of the fiber was longer than that in example 1. The coloring time of electrochromic fiber was 2.1 s and the bleaching time was 1.9 s.