A self-healing hydrogel electrolyte for electrochromic energy storage dual-functional devices

Abstract

The present invention relates to a self-healing hydrogel electrolyte for electrochromic energy storage dual-functional devices. The hydrogel uses a deionized water / glycerol mixture as a solvent, a graft copolymer of polyvinyl alcohol and acrylamide as the main monomer, potassium salts and zinc salts as electrolytes, and gelatin as an additive. By adjusting the addition amount of gelatin, a hydrogel electrolyte with good self-healing and anti-freezing properties is prepared by a cyclic freezing-thawing method. Further, the hydrogel electrolyte is used to prepare an electrochromic energy storage dual-functional device, which exhibits good electrochromic and energy storage properties in the temperature range of -30°C to 30°C and is suitable for the preparation of flexible devices. The preparation method of the novel hydrogel electrolyte involved in the present invention is simple, the raw materials are cheap and easily available, the ionic conductivity is high, the transparency is high, and the self-healing performance is good, having broad application prospects in the field of electrochromic energy storage.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a self-healing hydrogel electrolyte, and particularly to the preparation of a self-healing modified polyvinyl alcohol-based hydrogel electrolyte for electrochromic energy storage dual-functional devices, belonging to the field of electrochromic technology. Background Art

[0002] Since the discovery of the electrochromic phenomenon in 1969, it has received extensive attention and has potential applications in display, light radiation, and transmission management. Electrochromic glass can not only reduce the energy consumption generated by building heating, air conditioning, and ventilation, but also reduce glare, not damage natural lighting, and bring higher indoor comfort with unobstructed vision. At the same time, it has the characteristics of easy control, good energy-saving effect, and color memory. From the perspective of electrochemical principles and device structures, electrochromic devices have both a device structure similar to that of energy storage devices such as batteries and supercapacitors, and similar charge transfer, storage, and elemental valence state change processes. Through reasonable design, a dual-functional device with energy storage and electrochromic functions can be developed, which has the function of energy storage while changing color. As a new type of electrochemical device, electrochromic and energy storage dual-functional devices have broad application prospects in the fields of energy conservation and energy storage.

[0003] In electrochromic energy storage devices, traditional liquid electrolytes have problems such as easy leakage and difficult encapsulation. Hydrogels are functional polymer materials with a three-dimensional network structure formed by hydrophilic polymers using water as the dispersion medium, thus overcoming these problems. Hydrogels contain a large number of free water molecules and usually have high ionic conductivity; the highly cross-linked polymer network makes the hydrogel have excellent mechanical properties and deformation ability. Therefore, hydrogel electrolytes have extensive applications in electrochromic devices. In order to provide better stability and extend the service life, hydrogels with self-healing ability have attracted much attention due to their ability to spontaneously heal after being damaged. Generally speaking, the self-healing properties of polymer hydrogels come from the dynamic covalent bonds and non-covalent interactions between polymer chains.

[0004] Currently, traditional polymer hydrogel electrolytes are usually used to manufacture flexible electrochromic devices or energy storage devices, but when suffering from external mechanical damage or harsh environments, due to the lack of self-healing characteristics, the service life of the devices is severely limited. Therefore, it is of great significance to develop a hydrogel electrolyte that can be used in devices with electrochromic and energy storage dual functions and has significant self-healing performance. Summary of the Invention

[0005] Aiming at the influence of the external environment on the electrolyte in electrochromic energy storage dual-functional devices, the present invention provides a preparation method for a self-healing hydrogel electrolyte for electrochromic energy storage dual-functional devices.

[0006] Another object of the present invention is to provide a simple method for fabricating an electrochromic energy storage dual-functional device. A hollow partition groove is fixed between two electrodes with 3M double-sided tape, and a hydrogel solution is poured into it. It is cured inside the device under cyclic freezing and thawing conditions; this can not only ensure a very thin electrolyte layer but also increase the service life of the device.

[0007] A self-healing hydrogel electrolyte for an electrochromic energy storage dual-functional device and the preparation of the device include the following steps:

[0008] (1) Preparation of modified polyvinyl alcohol: Acrylamide (AM) is grafted onto polyvinyl alcohol (PVA) to prepare modified polyvinyl alcohol (PVA-g-AM). This copolymerization reaction is carried out under a nitrogen atmosphere, with PVA and AM as monomers. After obtaining a uniform PVA solution, AM is added, and a mixture of ammonium cerium nitrate and concentrated sulfuric acid is used as an initiator for initiation. After the reaction ends, the product is cooled to room temperature, then precipitated with acetone, washed several times with an acetone-water mixture to remove homopolymers, finally washed with pure acetone, and dried in an oven at 40 °C to finally obtain PVA-g-PAM;

[0009] (2) Preparation of the hydrogel electrolyte: Under the condition of 80 °C, PVA-g-PAM is added to a mixed solvent of deionized water / glycerol. After fully stirring and dissolving, potassium salt, zinc salt, and an additive are added in sequence, and after stirring and dissolving, a hydrogel solution is obtained;

[0010] (3) Preparation of the electrode material: Prussian blue film is deposited on conductive glass by a constant current deposition method as the anode of the electrochromic energy storage dual-functional device; zinc foil is used as the cathode of the electrochromic energy storage device;

[0011] (4) Fabrication of the electrochromic energy storage dual-functional device: A hollow partition groove is fixed between the two electrodes prepared in step (2) with 3M double-sided tape, and the hydrogel solution prepared in step (1) is dropped into it. After cyclic freezing and thawing three times, the hydrogel is cured to obtain an electrochromic energy storage dual-functional device based on a modified polyvinyl alcohol-based self-healing hydrogel.

[0012] In step (1), the concentrations of both PVA and AM are 0.1 g / mL, the amount of ammonium cerium nitrate is 0.084 mmol, the amount of concentrated sulfuric acid is 1.2 mL, the reaction temperature is 85 °C, and the reaction time is 12 hours.

[0013] In step (1), the volume ratio of deionized water to glycerol in the mixed solvent of deionized water / glycerol is 2:1.

[0014] In step (2), the potassium salt is potassium chloride with a concentration of 0.9 mol / L; the zinc salt is one of zinc sulfate, zinc acetate, or zinc trifluoromethanesulfonate, with a concentration of 0.1 mol / L.

[0015] In step (2), the additive is gelatin. As an interpenetrating network segment, the mass ratio of gelatin to PVA-g-PAM is 1:1 to 6.

[0016] During the electrodeposition process in step (3), indium tin oxide (ITO) conductive glass is used as the working electrode, a platinum wire as the counter electrode, and a silver wire as the reference electrode.

[0017] During the device preparation process in step (4), the thickness of the 3M double-sided tape is 400 μm, and the thickness of the zinc foil is 80 μm.

[0018] The present invention has the following advantages:

[0019] The method for preparing the hydrogel electrolyte in the present invention is simple, and the hydrogel has self-healing properties. It can maintain a complete morphological feature and a very high ionic conductivity in the range of -30°C to 30°C. The device based on this hydrogel can also have excellent electrochromic and energy storage properties in the range of -30°C to 30°C, and has good application prospects in the fields of intelligent color-changing windows and flexible electronic devices. Description of the Drawings

[0020] Figure 1 It is a structural diagram of an electrochromic energy storage dual-functional device.

[0021] Figure 2 It is the infrared spectrum of the graft copolymerization of PVA and PAM, and the infrared spectrum of the hydrogel electrolyte prepared based on this. It can be seen from the figure that the characteristic functional groups of PVA and PAM can all be reflected, proving the success of the graft copolymerization of PVA and PAM; after adding the additive, some characteristic peaks of the hydrogel shift towards lower wavenumbers, indicating the existence of hydrogen bond interaction between PVA-g-PAM and the additive.

[0022] Figure 3 It is an optical microscope picture of the self-healing process of the self-healing hydrogel electrolyte.

[0023] Figure 4 It is the ultraviolet absorption spectrum and coloring efficiency at room temperature of the electrochromic energy storage device made of the hydrogel in Example 1; it can be seen from the figure that the maximum absorption wavelength of the device is 680 nm, and at 680 nm, the device has a relatively high coloring efficiency.

[0024] Figure 5 It is the constant current charge-discharge curve of the electrochromic energy storage dual-functional device; the results show that when discharging at a low current density of 0.02 mA / cm 2 the device has an area capacitance of 35.2 mA·h / m 2 and a high Coulomb efficiency of 97.6%. At a high current density of 0.8 mA / cm 2 it can still provide 25.7 mA·h / m 2capacity; meanwhile, it still retains the energy storage property at low temperature, and the capacity is 15.0 mA·h / m at -30°C 2 . Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described below in conjunction with embodiments.

[0026] Embodiment 1

[0027] (1) Preparation of modified polyvinyl alcohol:

[0028] The copolymerization reaction of PVA and AM is carried out under a nitrogen atmosphere. First, 2.0 g of PVA and 20 mL of deionized water are added to a flask, and the PVA is completely dissolved at 85°C. Then, 2.0 g of AM is added to the solution, and finally, 0.046 g of ammonium cerium nitrate and 1.2 mL of concentrated sulfuric acid are added as initiators for initiation and the reaction continues for 12 hours. After the reaction is completed, the product is cooled to room temperature, then precipitated with 100 mL of acetone, washed 10 times with an acetone-water mixture (7:3, volume ratio) to remove homopolymers, and finally washed with pure acetone and dried in an oven at 40°C to finally obtain PVA-g-PAM;

[0029] (2) Preparation of hydrogel electrolyte:

[0030] At 80°C, 0.5 g of PVA-g-PAM is added to 5 mL of a mixed solvent of deionized water-glycerol (2:1, volume ratio), and stirred until dissolved; 0.1 g of gelatin is weighed and added to the solution, and stirring continues for 20 minutes; then 0.9 mol / L of potassium chloride and 0.1 mol / L of zinc trifluoromethanesulfonate are added until completely dissolved; after stirring for 30 minutes, a hydrogel solution is obtained;

[0031] (3) Preparation of electrodes:

[0032] Prussian blue thin films are prepared by the constant current deposition method. 0.329 g of potassium ferricyanide, 0.162 g of ferric chloride, 0.746 g of potassium chloride and 1 mol / L of hydrochloric acid are dissolved in 100 mL of deionized water to obtain an electroplating solution, and deposited at a constant current of 50 μA for 800 seconds; during the electroplating process, ITO conductive glass is used as the working electrode, a platinum wire is used as the counter electrode, and a silver wire is used as the reference electrode;

[0033] (4) Preparation of electrochromic energy storage devices:

[0034] Use 3M double-sided tape to fix a hollow partition with a certain size and thickness on the ITO conductive glass deposited with Prussian blue film. Drop the above-mentioned homogeneous hydrogel solution into the partition, then stick the cut zinc foil onto the 3M double-sided tape, and freeze-thaw three times at -20°C and room temperature to solidify the hydrogel, obtaining an electrochromic energy storage device based on the modified polyvinyl alcohol-based self-healing hydrogel.

[0035] Example 2

[0036] (1) The preparation method of the modified polyvinyl alcohol is the same as that in Example 1.

[0037] (2) Preparation of the hydrogel electrolyte:

[0038] At 80°C, add 0.6 g of PVA-g-PAM to 6 mL of a mixed solvent of deionized water-glycerol (2:1, volume ratio), stir until dissolved; weigh 0.2 g of gelatin and add it to this solution, continue stirring for 20 minutes; then add 0.9 mol / L potassium chloride and 0.1 mol / L zinc trifluoromethanesulfonate until completely dissolved; after stirring for 30 minutes, a hydrogel solution is obtained.

[0039] (3) The preparation methods of the electrodes and the electrochromic energy storage device are the same as those in Example 1.

[0040] Example 3

[0041] (1) The preparation method of the modified polyvinyl alcohol is the same as that in Example 1.

[0042] (2) Preparation of the hydrogel electrolyte:

[0043] At 80°C, add 0.5 g of PVA-g-PAM to 5 mL of a mixed solvent of deionized water-glycerol (2:1, volume ratio), stir until dissolved; weigh 0.1 g of gelatin and add it to this solution, continue stirring for 20 minutes; then add 0.9 mol / L potassium chloride and 0.1 mol / L zinc sulfate until completely dissolved; after stirring for 30 minutes, a hydrogel solution is obtained.

[0044] (3) The preparation methods of the electrodes and the electrochromic energy storage device are the same as those in Example 1.

[0045] Example 4

[0046] (1) The preparation method of the modified polyvinyl alcohol is the same as that in Example 1.

[0047] (2) Preparation of the hydrogel electrolyte:

[0048] At 80 °C, 0.5 g of PVA-g-PAM was added to 5 mL of a mixed solvent of deionized water and glycerol (2:1, volume ratio), and stirred until dissolved; 0.1 g of gelatin was weighed and added to the solution, and stirring was continued for 20 minutes; then 0.9 mol / L potassium chloride and 0.1 mol / L zinc acetate were added until completely dissolved; after stirring for 30 minutes, a hydrogel solution was obtained;

[0049] (3) The preparation method of the electrode and the electrochromic energy storage device was the same as that in Example 1.

[0050] The purpose of the above embodiments is to enable those skilled in the art to understand the content of the present invention and implement it, and the protection scope of the present invention cannot be limited thereby. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of an electrochromic energy storage dual-functional device based on a modified polyvinyl alcohol-based self-healing hydrogel, characterized in that, The electrochromic energy storage dual-function device based on modified polyvinyl alcohol self-healing hydrogel consists of an ITO electrode deposited with electrochromic material, a transparent self-healing hydrogel electrolyte and a zinc foil electrode. The preparation method of the electrochromic energy storage dual-function device based on modified polyvinyl alcohol self-healing hydrogel comprises the following steps: (1) Preparation of modified polyvinyl alcohol: acrylamide AM was grafted onto polyvinyl alcohol PVA to prepare modified polyvinyl alcohol PVA-g-PAM: in a nitrogen atmosphere, polyvinyl alcohol PVA and acrylamide AM were used as precursors to obtain a uniform polyvinyl alcohol PVA solution, acrylamide AM was added, and a mixture of ammonium cerium nitrate and concentrated sulfuric acid was used as an initiator for initiation. After the reaction was completed, the product was cooled to room temperature, precipitated with acetone, and then washed with an acetone-water mixture several times to remove homopolymers, and finally washed with pure acetone and dried in a vacuum oven at 40 °C to finally obtain modified polyvinyl alcohol PVA-g-PAM; (2) Preparation of hydrogel electrolyte: Add modified polyvinyl alcohol PVA-g-PAM to a mixed solvent of deionized water / propylene glycol at 80°C, stir thoroughly to dissolve, then add potassium salt, zinc salt and additives in sequence, stir and dissolve to obtain a hydrogel solution; (3) Preparation of electrode materials: Prussian blue thin film was deposited on conductive glass by constant current deposition method as the anode of the electrochromic energy storage device; zinc foil was used as the cathode of the electrochromic energy storage device; (4) Preparation of electrochromic energy storage dual-function device: Use 3M double-sided tape to fix a hollow partition between the two electrodes prepared in step (2), and add the hydrogel solution prepared in step (1) dropwise into it. After three cycles of thawing and freezing, the hydrogel solidifies to obtain an electrochromic energy storage dual-function device based on modified polyvinyl alcohol self-healing hydrogel.

2. The preparation method of the electrochromic energy storage dual-functional device based on the modified polyvinyl alcohol-based self-healing hydrogel according to claim 1, wherein, In step (1), the concentrations of polyvinyl alcohol PVA and acrylamide AM are both 0.1 g / mL, the amount of ammonium cerium nitrate is 0.084 mmol, the amount of concentrated sulfuric acid is 1.2 mL, the reaction temperature is 85° C., and the reaction time is 12 hours.

3. The preparation method of the electrochromic energy storage dual-functional device based on the modified polyvinyl alcohol-based self-healing hydrogel according to claim 1, characterized in that, In step (2), the volume ratio of deionized water to glycerol in the deionized water / glycerol mixed solvent is 2:

1.

4. The preparation method of the electrochromic energy storage bifunctional device based on the modified polyvinyl alcohol-based self-healing hydrogel according to claim 1, characterized in that, In step (2), the potassium salt is potassium chloride with a concentration of 0.9 mol / L; the zinc salt is one of zinc sulfate, zinc acetate or zinc trifluoromethanesulfonate with a concentration of 0.1 mol / L.

5. The preparation method of the electrochromic energy storage bifunctional device based on the modified polyvinyl alcohol-based self-healing hydrogel according to claim 1, wherein, In step (2), the additive is gelatin, and the mass ratio of gelatin as an interpenetrating network segment to the modified polyvinyl alcohol PVA-g-PAM is 1:1 to 6.

6. The preparation method of the electrochromic energy storage bifunctional device based on the modified polyvinyl alcohol-based self-healing hydrogel according to claim 1, characterized in that, Step (3) During the electrodeposition process, ITO conductive glass is used as the working electrode, platinum wire is used as the counter electrode, and silver wire is used as the reference electrode.

7. The preparation method of the electrochromic energy storage dual-functional device based on the modified polyvinyl alcohol-based self-healing hydrogel according to claim 1, wherein, In step (4) of the device preparation process, the thickness of the 3 M double-sided tape is 400 μm; in step (3), the thickness of the zinc foil is 80 μm.

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