Bamboo cellulose-based gel electrolyte material with high strength and high ionic conductivity as well as preparation method and application of bamboo cellulose-based gel electrolyte material

Abstract

The invention discloses a preparation method of a bamboo cellulose-based gel electrolyte material with high strength and high ionic conductivity. The preparation method comprises the following steps: delignification treatment is carried out on bamboo chips, and the bamboo chips are washed and then stored in absolute ethyl alcohol; the preparation method comprises the following steps: dispersing polyvinyl alcohol in water, heating and dissolving, cooling, adding an acrylic monomer, ammonium persulfate and N, N '-methylene bisacrylamide, and continuously stirring until the materials are uniformly mixed to obtain colorless thick liquid; the bamboo chips treated in the first step are put into the liquid prepared in the second step, dipping is conducted for 12-15 h, vacuumizing treatment is conducted, the bamboo chips and the mixed liquid are put into a mold after dipping is completed, polymerization is conducted for 3-5 h in a drying oven at the temperature of 60-70 DEG C, then the bamboo chips are immersed in a salt solution with the concentration of 1-5 M for 3-5 h, and the bamboo cellulose-based gel electrolyte material is obtained; the preparation method is simple and convenient in process operation, relatively low in production cost, suitable for industrial production, excellent in mechanical strength and high in conductivity, and provides a new idea for manufacturing high-strength flexible electronic devices by using a hydrogel material.

Description

Technical Field

[0001] The present invention belongs to the field of flexible electronic technology, relates to gel electrolyte materials, and particularly relates to a high-strength and high-ion-conductive bamboo cellulose-based gel electrolyte material, a preparation method thereof, and an application thereof. Background Art

[0002] The overuse of fossil energy has led to increasingly severe environmental problems, thus promoting the rapid development of clean energy. Biomass materials, due to their rich sources and environmental friendliness, etc., the gel electrolytes prepared from biomass materials have been widely used in the field of supercapacitors. And the abundant functional groups of biomass materials provide reaction sites for various modifications, thus enabling the manufacture of multifunctional supercapacitors. However, there is a problem of mismatch between the mechanical properties and electrochemical properties of the current gel electrolytes, that is, most methods for enhancing the mechanical properties of gels (such as doping rigid materials, Hofmeister effect, etc.) cannot enhance the electrochemical properties of the electrolyte while enhancing the mechanical properties, and the use of some methods may also hinder ion transport, resulting in a decrease in electrochemical properties. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a high-strength and high-ion-conductive bamboo cellulose-based gel electrolyte material, a preparation method thereof, and an application thereof, which have excellent mechanical properties and a relatively high conductivity.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions to implement:

[0005] A preparation method of a high-strength and high-ion-conductive bamboo cellulose-based gel electrolyte material, comprising the following steps:

[0006] Step 1: Carry out delignification treatment on bamboo chips, wash them, and store them in absolute ethanol;

[0007] Step 2: Disperse polyvinyl alcohol in water, stir at 60 - 80 °C until dissolved, cool, and then add acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide, and continuously stir until evenly mixed to obtain a colorless viscous liquid; wherein, the mass ratio of polyvinyl alcohol, water, acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide is 1:24:9:0.045:(0.01 - 0.015) in sequence;

[0008] Step 3: Put the bamboo chips treated in Step 1 into the liquid prepared in Step 2, impregnate for 12 - 15 h, and carry out vacuum treatment. After completion, put the bamboo chips and the mixed solution into a mold, polymerize in an oven at 60 - 70 °C for 3 - 5 h, and then immerse in a salt solution with a concentration of 1 - 5 M for 3 - 5 h to obtain a bamboo cellulose-based gel electrolyte material.

[0009] The present invention also has the following technical features:

[0010] Preferably, the delignification process in step one includes: putting bamboo chips into a 1% sodium hydroxide solution, reacting at 80 - 90 °C for 12 h, washing with deionized water and then putting into a 3% sodium chlorite solution, reacting at 80 - 90 °C for 4 h.

[0011] Preferably, the delignification process in step one includes: putting bamboo chips into a 2.5 M NaOH solution, performing oil bath treatment at 110 - 120 °C for 2 h, washing with deionized water and then putting into a 1 wt% NaClO2 solution, performing oil bath treatment at 130 - 140 °C for 4 h.

[0012] Preferably, the delignification process in step one includes: putting bamboo chips into a mixed solution of 5 M sodium hydroxide solution and 0.8 M sodium sulfite solution with an equal volume ratio, reacting at 100 - 110 °C for 8 h.

[0013] Preferably, the delignification process in step one includes: adding 18 g of sodium hydroxide and 22.5 g of sodium thiosulfate to 90 g of deionized water to prepare a solution, putting bamboo chips into the solution and soaking for 2 h, then pouring it into the polytetrafluoroethylene inner liner of a hydrothermal reaction kettle. After assembling the reaction kettle, placing it in an oven at 120 °C for 3 h, then adjusting the oven temperature to 140 °C and continuing the reaction for 1 h.

[0014] Preferably, the washing in step one is to wash alternately with deionized water and absolute ethanol for 3 - 5 times.

[0015] Preferably, the vacuum pumping treatment in step three is to place the liquid with bamboo chips in a vacuum drying oven and pump to a pressure of -0.08 - -0.1 MPa, continue pumping for 10 minutes, then close and maintain the vacuum state for 10 minutes, repeating the above steps 3 - 5 times.

[0016] Preferably, the salt solution in step three includes any one of aqueous solutions of sodium chloride, sodium nitrate or sodium acetate with a concentration of 1 - 5 M.

[0017] The present invention also protects a high-strength and high-ion-conductive bamboo cellulose-based gel electrolyte material prepared by the method as described above and its application in high-strength flexible electronic devices.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] The present invention polymerizes polyvinyl alcohol, acrylic monomers, N,N'-methylenebisacrylamide and bamboo chips treated by delignification to form a bamboo cellulose-based gel. The mechanical properties of the bamboo chips treated by delignification are improved. While having high mechanical strength, they also have a certain degree of flexibility. Introducing the delignified bamboo cellulose skeleton into the gel matrix forms a dense polymer network, significantly enhancing the mechanical properties of the hydrogel. Further, immersing the bamboo cellulose-based gel in a salt solution, the cations in the salt solution can form weak hydrogen bond interactions with the bamboo cellulose, and the salt ions can be fully dissociated and move. The prepared bamboo cellulose-based gel electrolyte material has excellent mechanical properties and ion migration rate, and its conductivity at room temperature is 25.3 mS·cm -1 , and has a high tensile strength (≥78 MPa) and a certain degree of flexibility;

[0020] The process of the present invention is simple to operate and has a low production cost, suitable for industrial production, and has excellent mechanical strength, providing new ideas for manufacturing high-strength flexible electronic devices using hydrogel materials, such as high-strength supercapacitors, sensors, etc. Description of the Drawings

[0021] Figure 1 Optical photograph of the bamboo cellulose-based gel electrolyte material prepared in Example 1;

[0022] Figure 2 Stress-strain relationship diagram of the bamboo cellulose-based gel electrolyte material prepared in Example 1;

[0023] Figure 3 CV curve diagram of the carbon capacitor of the bamboo cellulose-based gel electrolyte material prepared in Example 1 at different scanning rates (10 - 50 mV / S);

[0024] Figure 4 GCD curve diagram of the carbon capacitor of the bamboo cellulose-based gel electrolyte material prepared in Example 1 at different current densities (0.5 - 5 A / g). Detailed Description of the Invention

[0025] The following further elaborates on the specific content of the present invention in conjunction with examples.

[0026] The raw materials used in the following examples are all obtained through conventional commercial channels, and the average molecular weight of polyvinyl alcohol is: 20,500.

[0027] The bamboo chips used in the following examples are taken from bamboo with an age of 2 - 3 years, with a thickness of 1 mm and a size of 2 cm × 5 cm.

[0028] Example 1

[0029] A preparation method of a high-strength and highly ion-conductive bamboo cellulose-based gel electrolyte material, comprising the following steps:

[0030] Step 1: Place bamboo slices with a thickness of 1 mm into a 1% sodium hydroxide solution, react at 85 °C for 12 h, wash with deionized water, then place them into a 3% sodium chlorite solution, react at 85 °C for 4 h, wash alternately with deionized water and absolute ethanol 3 times, and then store the bamboo slices in absolute ethanol;

[0031] Step 2: Disperse polyvinyl alcohol in water, stir at 60 °C until dissolved, add acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide after cooling, and continuously stir until evenly mixed to obtain a colorless viscous liquid; wherein, the mass ratio of polyvinyl alcohol, water, acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide is 1:24:9:0.045:0.01 in sequence;

[0032] Step 3: Place the bamboo slices treated in Step 1 into the liquid prepared in Step 2, impregnate for 12 h, place them in a vacuum drying oven and evacuate to a pressure of -0.08 MPa, continue to evacuate for 10 minutes, then close and maintain the vacuum state for 10 minutes. Repeat the above steps 3 times. After completion, put the bamboo slices and the mixed liquid into a mold, polymerize in an oven at 60 °C for 3 h, and then immerse them in an aqueous solution of sodium nitrate with a concentration of 3 M for 3 h to obtain the bamboo cellulose-based gel electrolyte material. Its optical photograph is as Figure 1 shown.

[0033] Testing and Analysis

[0034] 1) Mechanical property test: The tensile test of the bamboo cellulose-based gel electrolyte material was carried out on an electronic universal material testing machine. Tensile test: Cut the sample into strips to obtain specimens (length × width × thickness: 50 mm × 2 mm × 1 mm); the tensile speed is 60 mm / min; the test results of the stress-strain relationship of the gel electrolyte material prepared in Example 1 are as Figure 2 shown, and it can be seen from Figure 2 that the bamboo cellulose-based gel electrolyte material prepared in Example 1 has a tensile stress of 78.04 MPa, showing excellent mechanical properties.

[0035] 2) Assembly of supercapacitor and its electrochemical performance test:

[0036] Prepare an activated carbon electrode: Use commercial activated carbon as the active material, acetylene black as the conductive agent, and PTFE as the binder. Grind them into a slurry according to the mass ratio of 8:1:1, and coat it on a foam nickel current collector with a size of 1×2 cm 2 , and the coating area is 2 cm 2, after drying in a vacuum drying oven at 60 °C for 12 h, the electrode was immersed in a 3 M sodium nitrate solution for 12 h, taken out and dried for later use.

[0037] Assembly of the supercapacitor: The prepared bamboo cellulose-based gel electrolyte material was inserted into two symmetric activated carbon electrode sheets and sealed to obtain the supercapacitor.

[0038] Electrochemical performance test: The assembled supercapacitor was tested by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and alternating current impedance method (IMP) on an electrochemical workstation. The ionic conductivity of the bamboo cellulose-based gel electrolyte material was obtained by the alternating current impedance method. Test conditions: room temperature 25 °C, frequency 0.01 Hz to 100000 Hz, and the specific capacitance of the supercapacitor was 113 F / g.

[0039] The CV curve of the carbon capacitor with the bamboo cellulose-based gel electrolyte material prepared in Example 1 at different scanning rates (10 - 50 mV / S) is as Figure 3 shown. At a scanning rate of 10 - 50 mV / S, no irreversible redox peaks appeared.

[0040] The GCD curve of the carbon capacitor with the bamboo cellulose-based gel electrolyte material prepared in Example 1 at different current densities (0.5 - 5 A / g) is as Figure 4 shown. At a current density of 1 A / g, the specific capacitance of the assembled capacitor was 113 F / g.

[0041] Example 2

[0042] A preparation method of a high-strength and high-ion-conductivity bamboo cellulose-based gel electrolyte material, comprising the following steps:

[0043] Step 1: Put bamboo slices with a thickness of 1 mm into a 2.5 M NaOH solution, perform oil bath treatment at 120 °C for 2 h, wash with deionized water, then put into a 1 wt% NaClO2 solution, perform oil bath treatment at 140 °C for 4 h, wash alternately with deionized water and absolute ethanol 4 times, and then store the bamboo slices in absolute ethanol;

[0044] Step 2: Disperse polyvinyl alcohol in water, stir at 80 °C until dissolved, cool, add acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide, and continue to stir until evenly mixed to obtain a colorless viscous liquid; wherein, the mass ratio of polyvinyl alcohol, water, acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide is 1:24:9:0.045:0.012 in sequence;

[0045] Step 3: Put the bamboo slices processed in Step 1 into the liquid prepared in Step 2, impregnate for 15 h, place them in a vacuum drying oven, evacuate to a pressure of -0.1 MPa, continue to evacuate for 10 minutes, then close, maintain the vacuum state for 10 minutes, repeat the above steps 5 times. After completion, put the bamboo slices and the mixed liquid into a mold, polymerize in an oven at 65 °C for 5 h, and then immerse them in an aqueous solution of sodium chloride with a concentration of 5 M for 5 h to obtain a bamboo cellulose-based gel electrolyte material.

[0046] Example 3

[0047] A preparation method of a high-strength and high-ion-conductivity bamboo cellulose-based gel electrolyte material, comprising the following steps:

[0048] Step 1: Put bamboo slices with a thickness of 1 mm into a mixed solution of a 5 M sodium hydroxide solution and a 0.8 M sodium sulfite solution in an equal volume ratio, and react at 100 °C for 8 h. Wash alternately with deionized water and absolute ethanol 4 times, and then keep the bamboo slices in absolute ethanol;

[0049] Step 2: Disperse polyvinyl alcohol in water, stir at 70 °C until dissolved, add acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide after cooling, and continue to stir until evenly mixed to obtain a colorless viscous liquid; wherein, the mass ratio of polyvinyl alcohol, water, acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide is 1:24:9:0.045:0.015 in sequence;

[0050] Step 3: Put the bamboo slices processed in Step 1 into the liquid prepared in Step 2, impregnate for 13 h, place them in a vacuum drying oven, evacuate to a pressure of -0.09 MPa, continue to evacuate for 10 minutes, then close, maintain the vacuum state for 10 minutes, repeat the above steps 4 times. After completion, put the bamboo slices and the mixed liquid into a mold, polymerize in an oven at 70 °C for 4 h, and then immerse them in an aqueous solution of sodium acetate with a concentration of 1 M for 4 h to obtain a bamboo cellulose-based gel electrolyte material.

[0051] Example 4

[0052] A preparation method of a high-strength and high-ion-conductivity bamboo cellulose-based gel electrolyte material, comprising the following steps:

[0053] Step 1: Add 18 g of sodium hydroxide and 22.5 g of sodium thiosulfate to 90 g of deionized water to prepare a solution. Put bamboo slices with a thickness of 1 mm into the solution, soak for 2 h, then pour them into the polytetrafluoroethylene inner liner of a hydrothermal reaction kettle. After assembling the reaction kettle, place it in an oven at 120 °C, react for 3 h, then adjust the oven temperature to 140 °C, and continue to react for 1 h. Wash alternately with deionized water and absolute ethanol 5 times, and then keep the bamboo slices in absolute ethanol;

[0054] Step 2: Dissolve polyvinyl alcohol in water, stir at 65 °C until dissolved, and after cooling, add acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide and continuously stir until evenly mixed to obtain a colorless viscous liquid; among them, the mass ratio of polyvinyl alcohol, water, acrylic acid monomer, ammonium persulfate, and N,N'-methylenebisacrylamide is 1:24:9:0.045:0.013 in sequence;

[0055] Step 3: Put the bamboo slices treated in Step 1 into the liquid prepared in Step 2, soak for 14 h, place them in a vacuum drying oven and evacuate to a pressure of -0.08 MPa, continue to evacuate for 10 minutes, then close and maintain the vacuum state for 10 minutes, repeat the above steps 5 times. After completion, put the bamboo slices and the mixed solution into a mold, polymerize in an oven at 60 °C for 5 h, and then immerse in an aqueous solution of sodium chloride with a concentration of 2 M for 5 h to obtain a bamboo cellulose-based gel electrolyte material.

[0056] Example 5

[0057] Example 5 is basically the same as Example 1, the only difference being that the reaction temperatures of the bamboo slices in the sodium hydroxide solution and the sodium chlorite solution in Step 1 are both 90 °C.

[0058] Example 6

[0059] Example 6 is basically the same as Example 1, the only difference being that the reaction temperatures of the bamboo slices in the sodium hydroxide solution and the sodium chlorite solution in Step 1 are both 80 °C.

[0060] Example 7

[0061] Example 7 is basically the same as Example 2, the only difference being that the reaction temperature of the bamboo slices in the sodium hydroxide solution in Step 1 is 110 °C, and the reaction temperature in the sodium chlorite solution is 130 °C.

[0062] Example 8

[0063] Example 8 is basically the same as Example 2, the only difference being that the reaction temperature of the bamboo slices in the sodium hydroxide solution in Step 1 is 115 °C, and the reaction temperature in the sodium chlorite solution is 135 °C.

[0064] Example 9

[0065] Example 9 is basically the same as Example 3, the only difference being that the reaction temperature of the bamboo slices in the mixed solution in Step 1 is 110 °C.

[0066] Example 10

[0067] Example 10 is basically the same as Example 3, the only difference being that the reaction temperature of the bamboo slices in the mixed solution in Step 1 is 105 °C.

[0068] It should be noted that the embodiments described above are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material, characterized in that: The following steps are involved: Step 1, delignifying the bamboo slices, washing them and storing them in anhydrous ethanol; Step 2: Disperse polyvinyl alcohol in water, stir at 60-80° C. until dissolved, add acrylic acid monomer, ammonium persulfate and N,N'-methylenebisacrylamide after cooling, and continue stirring until mixed evenly to obtain a colorless viscous liquid; wherein the mass ratios of polyvinyl alcohol, water, acrylic acid monomer, ammonium persulfate and N,N'-methylenebisacrylamide are 1:24:9:0.045:(0.01-0.015) respectively; Step 3: Place the bamboo chips treated in step 1 into the liquid prepared in step 2, immerse for 12 to 15 hours, and perform vacuum treatment. After the treatment, place the bamboo chips and the mixed liquid into a mold, polymerize in an oven at 60 to 70° C. for 3 to 5 hours, and then immerse in a salt solution with a concentration of 1 to 5 M for 3 to 5 hours to obtain a bamboo cellulose-based gel electrolyte material.

2. The method for preparing the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material according to claim 1, characterized in that: The delignification treatment process described in step 1 includes: placing the bamboo chips in a 1% sodium hydroxide solution, reacting at 80-90° C. for 12 hours, washing with deionized water, placing in a 3% sodium chlorite solution, and reacting at 80-90° C. for 4 hours.

3. The method for preparing the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material according to claim 1, characterized in that: The delignification treatment process described in step 1 includes: placing the bamboo pieces in a 2.5M NaOH solution, treating them in an oil bath at 110-120°C for 2 hours, washing them with deionized water, placing them in a 1wt% NaClO2 solution, and treating them in an oil bath at 130-140°C for 4 hours.

4. The method for preparing the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material according to claim 1, characterized in that: The delignification treatment process described in step 1 includes: placing the bamboo pieces in a mixed solution of 5M sodium hydroxide solution and 0.8M sodium sulfite solution in equal volume ratio, and reacting at 100-110° C. for 8 hours.

5. The method for preparing the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material according to claim 1, characterized in that: The delignification treatment process described in step one includes: adding 18g of sodium hydroxide and 22.5g of sodium thiosulfate to 90g of deionized water to prepare a solution, soaking the bamboo pieces in the solution for 2h and then pouring them into the polytetrafluoroethylene liner of the hydrothermal reactor. After assembling the reactor, place it in an oven at 120°C for reaction for 3h, then adjust the oven temperature to 140°C and continue the reaction for 1h.

6. The method for preparing the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material according to claim 1, characterized in that: The washing described in step 1 is washing with deionized water and anhydrous ethanol alternately for 3 to 5 times.

7. The method for preparing the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material according to claim 1, characterized in that: The vacuum treatment described in step three is to place the liquid containing the bamboo chips in a vacuum drying oven and evacuate it to a pressure of -0.08 to -0.1 MPa, continue to evacuate for 10 minutes, then close it, maintain the vacuum state for 10 minutes, and repeat the above steps 3 to 5 times.

8. The method for preparing the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material according to claim 1, characterized in that: The salt solution described in step 3 includes any one of aqueous solutions of sodium chloride, sodium nitrate or sodium acetate with a concentration of 1 to 5M.

9. A high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material prepared by the method according to any one of claims 1 to 8.

10. Use of the high-strength, high-ion-conductivity bamboo cellulose-based gel electrolyte material as claimed in claim 9 in high-strength flexible electronic devices.

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