Preparation method of inorganic filler doped gel electrolyte, product and application thereof

Abstract

The application discloses a preparation method of an inorganic filler doped gel electrolyte, and a product and application thereof, and belongs to the technical field of new materials. The gel electrolyte with high ionic conductivity is prepared by using dopamine modified boron nitride as inorganic nano filler, polyvinyl alcohol as polymer, and the mechanism of increasing hydrogen bond density and increasing ion transmission channels. The gel electrolyte has good mechanical properties, is bendable, and has high ionic conductivity. When the gel electrolyte is applied to a micro super capacitor, a flexible micro super capacitor with excellent electrochemical performance can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, and in particular relates to a method for preparing inorganic filler-doped gel electrolytes, as well as their products and applications. Background Technology

[0002] In recent years, people have been increasingly demanding portable and wearable flexible energy storage devices. Fabric-based micro supercapacitors (MSCs) have received extensive research and attention due to their advantages such as small size, environmental friendliness, arbitrary shape design, fast charging and discharging speed and long cycle life.

[0003] Electrolytes, as a crucial component of mechatronics (MSCs), play a vital role in electrochemical performance. Liquid electrolytes, however, present numerous challenges due to leakage, volume expansion, electrode corrosion, and difficulties in designing diverse shapes, posing safety risks in practical applications. Gel electrolytes, on the other hand, not only function as both electrolytes and membranes but also possess elasticity and strength through a three-dimensional network structure, ensuring the free diffusion of ions. Therefore, gel electrolytes hold great promise for applications in micro supercapacitors.

[0004] Polyvinyl alcohol (PVA) is one of the most widely used electrolytes in MSCs due to its good hydrophilicity and film-forming properties, as well as its low price, non-toxicity, and the large number of hydroxyl groups in its main chain. However, PVA-based gel electrolytes have problems such as low mechanical properties and low ionic conductivity, which reduce the energy storage performance of the devices. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a method for preparing an inorganic filler-doped gel electrolyte, along with its products and applications. This gel electrolyte exhibits good mechanical properties, flexibility, and high ionic conductivity. When applied to micro supercapacitors, it can yield flexible micro supercapacitors with excellent electrochemical performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing an inorganic filler-doped gel electrolyte includes the following steps:

[0008] Tris(hydroxymethyl)aminomethane, deionized and ethanol were mixed, boron nitride was added and ultrasonically dispersed, then dopamine was added, stirred at room temperature, allowed to stand, the supernatant was removed and dried to obtain the modified inorganic filler.

[0009] The modified inorganic filler was added to deionized water and mixed well. Then polyvinyl alcohol was added and stirred under water bath heating. After the polyvinyl alcohol was completely dissolved, the water bath temperature was reduced and potassium hydroxide solution was added dropwise. Stirring was continued until the solution was homogeneous, thus obtaining the inorganic filler-doped gel electrolyte.

[0010] Further, in step 1), the ratio of the amount of tris(hydroxymethyl)aminomethane, deionized water, ethanol, boron nitride and dopamine is 0.6g:150mL:50mL:1g:0.4g.

[0011] Further, in step 1), the ultrasonic dispersion time is 10 min; the room temperature stirring time is 6 h; the standing time is 24 h; and the drying is performed at 60°C for 12 h.

[0012] Further, in step 2), the amount of modified inorganic filler added is 0.015-0.025 mg / mL; the amount of polyvinyl alcohol added is 40-80 g / L; and the concentration of potassium hydroxide solution is 1.0-3.0 mol / L.

[0013] Further, in step 2), the water bath heating temperature is 90°C and the stirring time is 2 hours; potassium hydroxide solution is added dropwise when the water bath temperature is lowered to 80°C.

[0014] This invention also provides an inorganic filler-doped gel electrolyte prepared using the above-described method. The polyvinyl alcohol polymer chains and hydrogen bonds between polar groups in this gel electrolyte form conductive pathways. Furthermore, the addition of dopamine-modified boron nitride further increases the hydrogen bond density, reduces crystallinity, constructs ion transport channels, and imparts better mechanical properties.

[0015] The present invention also provides an application of inorganic filler-doped gel electrolyte as an electrolyte material for micro supercapacitors.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects:

[0017] This invention uses dopamine-modified boron nitride as an inorganic nanofiller and polyvinyl alcohol as a polymer, and employs the mechanism of increasing hydrogen bond density and increasing ion transport channels to prepare a gel electrolyte with high ionic conductivity.

[0018] The inorganic filler-doped gel electrolyte prepared by this invention has an ionic conductivity of 112.1 mS / cm and an elongation at break of 100.6%.

[0019] The assembled inorganic filler-doped gel electrolyte-based micro supercapacitor exhibits excellent electrochemical performance, with an areal capacitance of 216 mF / cm². 2 The rate capability is 68.8%, and the energy density is 0.88 μWh / cm³. 2 Increased to 14.7 μWh / cm 2 After 5000 cycles, the capacitance retention rate reached 92.2%.

[0020] In summary, this invention is simple in design and safe in process, and realizes a gel electrolyte with high porosity, bendability, high mechanical properties and high ionic conductivity. This gel electrolyte can be used to improve the electrochemical performance of micro supercapacitors, expand their application range, and is expected to achieve large-scale application. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 This is a schematic diagram of the fabrication process of the inorganic filler-doped gel electrolyte-based micro supercapacitor of the present invention;

[0023] Figure 2 Optical images of polyvinyl alcohol gel electrolytes prepared in Example 1 and Control Group 1;

[0024] Figure 3 The ionic conductivity of gel electrolytes with different amounts of dopamine-modified boron nitride in Examples 1-5;

[0025] Figure 4 FTIR spectra of BN-PDA, PVA / KOH, and PVA / KOH / BN-PDA gel electrolytes in Example 1 and Control Group 1;

[0026] Figure 5 The X-ray diffraction patterns of PVA / KOH / BN-PDA and PVA / KOH gel electrolytes in Example 1 and Control Group 1 are shown below.

[0027] Figure 6 Thermogravimetric curves of PVA / KOH / BN-PDA and PVA / KOH gel electrolytes in Example 1 and Control Group 1 are shown.

[0028] Figure 7 Cyclic voltammetry curves of the micro supercapacitors assembled with PVA / KOH / BN-PDA, PVA / KOH, and PVA gel electrolytes in Example 1, Control Group 1, and Control Group 2;

[0029] Figure 8 The charge-discharge curves of the micro supercapacitors assembled with PVA / KOH / BN-PDA, PVA / KOH, and PVA gel electrolyte in Example 1, Control Group 1, and Control Group 2 are shown.

[0030] Figure 9 Electrochemical impedance spectroscopy of the micro supercapacitors assembled with PVA / KOH / BN-PDA, PVA / KOH, and PVA gel electrolyte in Example 1, Control Group 1, and Control Group 2;

[0031] Figure 10 The charge-discharge curves of the micro supercapacitor assembled with PVA / KOH / BN-PDA gel electrolyte in Example 1 at different current densities are shown.

[0032] Figure 11 The specific capacitance of the micro supercapacitors assembled with PVA / KOH and PVA / KOH / BN-PDA gel electrolytes in Example 1 and Control Group 1 at different current densities;

[0033] Figure 12 Cyclic curve of the micro supercapacitor assembled with PVA / KOH / BN-PDA gel electrolyte in Example 1. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0037] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0038] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0039] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0040] All raw materials used in the following embodiments of the present invention are commercially available:

[0041] Boron nitride (BN) was purchased from Jiangxi Liankai New Materials Co., Ltd. Dopamine hydrochloride, tris(hydroxymethyl)aminomethane, and potassium hydroxide were purchased from Sinopharm Chemical Reagent Co., Ltd. Polyvinyl alcohol and ethanol were purchased from Shanghai Titan Technology Co., Ltd. Multi-walled carbon nanotubes were purchased from Shenzhen Nanoport Materials Co., Ltd. Cotton fabrics were purchased from Jiangsu Dayao Textile Co., Ltd.

[0042] This invention aims to improve mechanical properties and ionic conductivity by introducing inorganic nanofillers into a PVA-based gel electrolyte system. Utilizing the advantages of high specific surface area, high surface free energy, and nanoscale size, inorganic nanofillers can, on the one hand, construct ion transport channels and increase the porosity of the gel, thus promoting ion transport speed; on the other hand, they can reduce the crystallinity of the gel electrolyte, increase the proportion of amorphous regions, reduce ion transport resistance, and improve the conductivity of the gel electrolyte, thereby enhancing the electrochemical performance of the gel electrolyte and its devices.

[0043] A method for preparing an inorganic filler-doped gel electrolyte includes the following steps:

[0044] Step 1: Add 1.2g of tris(hydroxymethyl)aminomethane to a mixed solution of 300mL deionized water and 100mL ethanol, then add 2g of boron nitride and ultrasonically disperse for 10min. Add 0.8g of dopamine, stir at room temperature for 6h until gray-black, let stand for 24h, remove the supernatant, and dry at 60℃ for 12h to obtain the modified inorganic filler (denoted as dopamine-modified boron nitride).

[0045] Step 2: Weigh out KOH solid and dissolve it in 20 mL of deionized water for later use; then add the modified inorganic filler to 30 mL of deionized water and mix well, then weigh out polyvinyl alcohol and add it to the mixture, place it in a 90℃ water bath and stir continuously for 2 hours. After the polyvinyl alcohol is completely dissolved, lower the temperature of the water bath to 80℃ and slowly add KOH solution dropwise, continuing to stir until the solution is uniform, thus obtaining the inorganic filler-doped gel electrolyte.

[0046] In step 2, the concentration of KOH is 1.0-3.0 mol / L, the amount of PVA added is 40-80 g / L, and the amount of modified inorganic filler is 0.015-0.025 mg / mL, preferably 0.020 mg / mL.

[0047] This invention also provides an inorganic filler-doped gel electrolyte prepared using the above-described method. The polyvinyl alcohol polymer chains and hydrogen bonds between polar groups in this gel electrolyte form conductive pathways. Furthermore, the addition of dopamine-modified boron nitride further increases the hydrogen bond density, reduces crystallinity, constructs ion transport channels, and imparts better mechanical properties.

[0048] This invention also provides an application of an inorganic filler-doped gel electrolyte as an electrolyte material for micro supercapacitors. Figure 1 This is a schematic diagram of the fabrication process of the inorganic filler-doped gel electrolyte-based micro supercapacitor of the present invention.

[0049] The following embodiments are further illustrations of the technical solution of the present invention.

[0050] Example 1

[0051] 1) Add 1.2g of tris(hydroxymethyl)aminomethane to a mixed solution of 300mL of deionized water and 100mL of ethanol (AR specification), then add 2g of boron nitride and ultrasonically disperse for 10min. Add 0.8g of dopamine, stir at room temperature for 6h until gray-black, let stand for 24h, remove the supernatant, and dry at 60℃ for 12h to obtain the modified inorganic filler (denoted as dopamine modified boron nitride, BN-PDA);

[0052] 2) Weigh 5.611 g of KOH solid and dissolve it in 20 mL of deionized water to prepare a KOH solution for later use. Then, add the modified inorganic filler prepared in step 1) to 30 mL of deionized water at a ratio of 0.020 mg / mL (weighed according to the total amount of 50 mL of deionized water) and mix well. Then weigh 3 g of polyvinyl alcohol (PVA) and add it to the solution. Place the solution in a 90°C water bath and stir continuously for 2 hours. After the polyvinyl alcohol is completely dissolved, lower the temperature of the water bath to 80°C and slowly add the KOH solution dropwise. Continue stirring until the solution is homogeneous to obtain the inorganic filler-doped gel electrolyte (denoted as PVA / KOH / BN-PDA).

[0053] Example 2

[0054] Same as Example 1, except that the amount of modified inorganic filler used is 0.015 mg / mL.

[0055] Example 3

[0056] Same as Example 1, except that the amount of modified inorganic filler used is 0.025 mg / mL.

[0057] Example 4

[0058] Same as Example 1, except that the amount of modified inorganic filler used is 0.010 mg / mL.

[0059] Example 5

[0060] Same as Example 1, except that the amount of modified inorganic filler used is 0.035 mg / mL.

[0061] Control group 1

[0062] Preparation of PVA / KOH:

[0063] Weigh out 3g of polyvinyl alcohol and add it to 30mL of deionized water. Place the solution in a 90℃ water bath and stir continuously for 2 hours. After the polyvinyl alcohol is completely dissolved, lower the temperature of the water bath to 80℃ and slowly add KOH solution (5.611g KOH, 20mL deionized water). Continue stirring until the solution is homogeneous to obtain PVA / KOH gel electrolyte.

[0064] Control group 2

[0065] Polyvinyl alcohol (PVA) itself was used as the gel electrolyte. The method was as follows: 3 g of PVA was weighed and added to 50 mL of deionized water. The mixture was placed in a 90 °C water bath and stirred continuously for 2 h. After the PVA was completely dissolved, it was cooled to room temperature to obtain the PVA gel electrolyte.

[0066] Figure 2 Optical images of polyvinyl alcohol gel electrolytes prepared in control group 1 and example 1 are shown. As can be seen from the images, the color of the gel electrolyte changed from white to gray after the addition of BN-PDA, indicating that the color of the PVA / KOH / BN-PDA gel electrolyte is affected by the color of BN-PDA.

[0067] Figure 3 The figures show the ionic conductivity of gel electrolytes with different amounts of dopamine-modified boron nitride in Examples 1-5. As can be seen from the figures, the highest ionic conductivity can reach 112.1 mS / cm. This is because when an appropriate amount of inorganic filler is added, the crystallinity and number of hydrogen bonds in the gel electrolyte can be reduced, which is beneficial to ion migration and improves the ionic conductivity.

[0068] The elongation at break test method was as follows: a universal testing machine was used to test the gel electrolyte samples at a tensile speed of 30 mm / min. Samples prepared in Examples 1-5 were tested. The results showed that the elongation at break of Example 1 reached 100.6%, while the elongation at break of the other examples was lower. This is because the proportion of amorphous regions in the gel electrolyte is increased, which is beneficial for elongation under external force.

[0069] Figure 4The figures show the FTIR spectra of BN-PDA, PVA / KOH, and PVA / KOH / BN-PDA gel electrolytes from Example 1 and Control Group 1. As can be seen from the figures, when BN-PDA is added to the gel electrolyte, more hydrogen bonds are formed in the -OH groups of the PVA chains, causing the characteristic peak to rise from 3355 cm⁻¹. -1 The position was moved to 3240cm -1 This indicates the successful hybridization of PVA and BN-PDA.

[0070] Figure 5 The X-ray diffraction patterns of PVA / KOH and PVA / KOH / BN-PDA gel electrolytes in Example 1 and Control Group 1 are shown in the figure. It can be seen from the figure that the intensity of the characteristic peaks of the X-ray diffraction pattern of PVA / KOH / BN-PDA gel electrolyte decreased compared with that of PVA / KOH gel electrolyte, indicating that the degree of crystallinity of the gel electrolyte was reduced.

[0071] Figure 6 The thermogravimetric curves of PVA / KOH and PVA / KOH / BN-PDA gel electrolytes in Example 1 and Control Group 1 are shown in the figure. It can be seen from the figure that there is some weight loss before 100℃, which is mainly caused by water in the gel electrolyte. The thermal decomposition temperature of the second stage is about 200-250℃, which is the decomposition of polymer side chains and functional groups. The thermal decomposition temperature of the third stage is 400-460℃, which is caused by the decomposition of polymer main chain segments. This shows that the PVA / KOH / BN-PDA gel electrolyte has high thermal stability and will not decompose at high temperatures.

[0072] Application Example 1

[0073] The gel electrolytes prepared in the above examples and control group were used to prepare micro supercapacitors. The specific method was as follows: First, cotton fabric was pretreated by adding it to a 15 g / L NaOH solution, heating to 95°C, and treating for 1 hour. Then, it was washed with deionized water until pH neutral and dried at 60°C for storage. Second, screen printing ink was prepared by mixing PVC-VAC resin and DBE at a mass ratio of 1:9. Graphene, acetylene black, and the above solution were then mixed and stirred evenly to obtain graphene ink. Finally, electrodes were screen printed. After screen printing, the fabric was placed in a vacuum oven at 100°C for 12 hours. After cooling, interdigitated electrodes for the micro supercapacitor were obtained. Liquid gel electrolyte was then coated onto the interdigitated electrode material to obtain the micro supercapacitor, and its performance was tested.

[0074] Figure 7The figures show the cyclic voltammetry curves of the micro supercapacitors assembled with PVA / KOH / BN-PDA, PVA / KOH, and PVA gel electrolytes in Example 1, Control Group 1, and Control Group 2. As can be seen from the figures, at the same scan rate, the CV curve integral area of ​​the PVA / KOH / BN-PDA gel electrolyte-based MSC is much larger than that of PVA and PVA / KOH.

[0075] Figure 8 The figures show the charge-discharge curves of the micro supercapacitors assembled with PVA / KOH / BN-PDA, PVA / KOH, and PVA gel electrolytes in Example 1, Control Group 1, and Control Group 2. As can be seen from the figures, the charge-discharge curves all exhibit approximately linear triangular shapes, indicating good reversibility. The PVA / KOH / BN-PDA gel electrolyte has stronger ion transport capabilities, and the addition of BN-PDA can increase the ion transport channels in the gel electrolyte.

[0076] Figure 9 The electrochemical impedance spectroscopy (EIS) plots of the micro supercapacitors assembled with PVA / KOH / BN-PDA, PVA / KOH, and PVA gel electrolyte in Example 1, Control Group 1, and Control Group 2 are shown. The plots show that the bulk resistances Rb of PVA, PVA / KOH, and PVA / KOH / BN-PDA are 912 Ω, 48.6 Ω, and 41.7 Ω, respectively. PVA / KOH / BN-PDA exhibits the lowest bulk resistance Rb, further confirming that the introduction of BN-PDA results in excellent ion transport efficiency.

[0077] Figure 10 The figure shows the charge-discharge curves of the micro supercapacitor assembled with PVA / KOH / BN-PDA gel electrolyte in Example 1 at different current densities. As can be seen from the figure, the galvanostatic charge-discharge curve has an approximately symmetrical triangular shape, and the discharge time is almost equal to the charging time, showing good capacitance performance at 1.2 mA / cm². 2 The area capacitance at that time was 216 mF / cm². 2 The calculated energy density is 0.88 μWh / cm³. 2 Increased to 14.7 μWh / cm 2 .

[0078] Figure 11 The specific capacitance of the micro supercapacitors assembled with PVA / KOH and PVA / KOH / BN-PDA gel electrolytes in Example 1 and Control Group 1 at different current densities can be used to calculate the rate performance. As shown in the figure, compared with the 32.3% capacitance retention of PVA / KOH, the capacitance retention of the micro supercapacitor assembled with PVA / KOH / BN-PDA gel electrolyte can reach 68.8%.

[0079] Figure 12 The graph shows the cycling curve of the micro supercapacitor assembled with PVA / KOH / BN-PDA gel electrolyte in Example 1. As can be seen from the graph, the capacitance retention rate of the micro supercapacitor still reaches 92.2% after 5000 cycles.

[0080] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for producing an inorganic filler-doped gel electrolyte, characterized by, It comprises the following steps: 1) mixing trihydroxymethyl aminomethane, deionized water and ethanol, adding boron nitride after ultrasonic dispersion, then adding dopamine, stirring at room temperature, standing, removing supernatant, drying to obtain a modified inorganic filler; the amount ratio of the trihydroxymethyl aminomethane, deionized water, ethanol, boron nitride and dopamine is 0.6g:150mL:50mL:1g:0.4g; 2) mixing the modified inorganic filler with deionized water, then adding polyvinyl alcohol, stirring under water bath heating, reducing the water bath temperature after the polyvinyl alcohol is completely dissolved, and adding potassium hydroxide solution dropwise, continuing to stir until the solution is uniform, to obtain an inorganic filler doped gel electrolyte; the amount of the modified inorganic filler added is 0.020mg / mL; the amount of the polyvinyl alcohol added is 40-80g / L; the concentration of the potassium hydroxide solution is 1.0-3.0mol / L.

2. The method for preparing an inorganic filler-doped gel electrolyte according to claim 1, characterized by, In step 1), the ultrasonic dispersion time is 10min; the stirring time at room temperature is 6h; the standing time is 24h; and the drying is carried out at 60℃ for 12h.

3. The method for preparing an inorganic filler-doped gel electrolyte according to claim 1, wherein In step 2), the water bath heating temperature is 90℃, and the stirring time is 2h; the potassium hydroxide solution is added dropwise when the water bath temperature is reduced to 80℃.

4. An inorganic filler doped gel electrolyte prepared by the preparation method of any one of claims 1-3.

5. Application of the inorganic filler doped gel electrolyte of claim 4 as a micro supercapacitor electrolyte material.

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