Method for preparing friction nanometer generator electrode based on tropical shell derived carbon

Abstract

The invention discloses a method for preparing a friction nano-generator electrode based on tropical shell derived carbon, which is used for collecting low-frequency mechanical energy generated by human body movement of hands, feet and the like, converting the low-frequency mechanical energy into electric energy, and performing simple pretreatment and carbonization treatment by taking tropical shells as biomass to obtain a porous biochar material. According to the friction nano-generator, the porous biochar material / polyvinyl alcohol / acidic solution compound is used as the electrode, the silicon-based polymer / polar solvent compound is used as the friction layer, and the electrode is packaged, so that the manufactured friction nano-generator has relatively high output performance; wherein the activated biochar has better performance output than the non-activated biochar on the friction nano-generator, the friction nano-generator can be used as an energy collection device and a motion sensor, and the friction nano-generator is wide in raw material source, simple in manufacturing process, low in material cost and suitable for popularization and application. And a potential practical way is provided for the aspects of collecting low-frequency mechanical energy generated by human body activities in a real environment, monitoring human body motions, supplying energy to portable equipment and the like.

Description

Technical Field

[0001] The invention relates to the technical field of biomass-derived carbon materials applied to friction nanogenerator electrode materials, in particular to the technical field of tropical fruit shells applied to friction nanogenerator electrode materials. Background Art

[0002] Global climate change and the environmental problems it causes are becoming increasingly serious. The high consumption of fossil fuels has led to increasingly prominent resource depletion and environmental pollution around the world. This phenomenon has not only had a profound impact on the ecosystem, but also posed a severe challenge to the sustainable development of human society. Therefore, it is particularly important to find renewable and sustainable energy solutions.

[0003] In this context, triboelectric nanogenerator (TENG), as an emerging clean energy technology, uses electrostatic induction and triboelectric effect to convert mechanical energy into electrical energy, showing the advantages of high efficiency, environmental protection and sustainability. It can effectively capture mechanical energy in the surrounding environment, provide power for small electronic devices, and promote the process of energy transformation. TENG is mainly composed of triboelectric layer and electrode. Most conductive materials, such as metal, carbon material and conductive glass, can be used as electrodes. Due to the excellent electrical conductivity, thermal conductivity and good stability of carbon material, it has been widely used in the manufacture of TENG by researchers in recent years [11, 12], however, common carbon materials (such as carbon nanotubes and graphene) are expensive, which limits the development of TENG. Patent CN113949305A discloses a method for preparing graphene micro-wrinkle TENG, which is characterized by controlling different recovery ratios of polymers to obtain graphene (rGO) micro-wrinkles of different morphologies. Compared with rGO with ordinary planar structure, the micro-wrinkle structure increases the friction contact area, which is beneficial to increase the number of transferred electrons, thereby greatly improving the output performance of TENG. However, graphene is expensive and difficult to promote and use on a large scale.

[0004] Compared with commercial carbon-based materials, biomass-derived carbon materials have the advantages of wide sources, low cost, environmental friendliness and rich surface functional groups. Generally, biomass-derived carbon materials can be easily produced from natural carbon sources or carbon residues in agricultural waste by physical and chemical activation methods. Therefore, using biomass waste as a precursor for preparing carbon materials and applying it to high-performance TENG has great development prospects. The recycling and reuse of waste to obtain new functional materials and devices is of great significance in environmental protection and sustainable energy development. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art and propose a preparation method and application of tropical fruit shells for TENG. Tropical fruit shells are a renewable resource. Processing them into biochar materials and applying them to TENG can reduce dependence on limited resources and reduce environmental impact. The prepared biochar materials have a high specific surface area and a reasonable pore structure, which helps to improve the energy conversion efficiency of TENG and simultaneously enhance the energy collection and self-powered sensing applications of TENG.

[0006] To achieve the above object, the present invention proposes a method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon, comprising the following steps: a) Pyrolysis: After the discarded tropical fruit shells are uniformly mixed with a low proportion of activating agent, pyrolysis carbonization is carried out by controlling the heating rate and pyrolysis atmosphere, and then the activating agent is removed by acid washing to obtain a porous biochar material; b) Electrode preparation: using the porous biochar material prepared in step a) as a matrix, mixing the prepared water-soluble polymer solution with the porous biochar material and the acid solution in a certain proportion, and then heating the mixture in a liquid bath to prepare a composite solution, which is then placed in an oven for drying to obtain an electrode material; c) Preparation of friction nanogenerator: The electrode material prepared in step b) is encapsulated with an organic silicon polymer added with a polar solvent.

[0007] Preferably, in step a), the mass mixing ratio of the activator to the tropical fruit shell is not higher than 25%; the activator is one or a combination of potassium hydroxide, zinc chloride, sodium bicarbonate, sodium carbonate, potassium carbonate, potassium bicarbonate, ethylenediamine phosphate, propylenediamine phosphate, ammonium sulfate, ammonium chloride, ammonium hydroxide, sodium fluorosilicate or ferrous sulfate; the heating rate is 5-15°C / min; the pyrolysis atmosphere is CO2; the final pyrolysis temperature is 650-950°C, and the pyrolysis time is 0.2-2h.

[0008] Preferably, in step a), the tropical fruit shell has high lignin content greater than 20%, and is one or a combination of several of the following: durian shell, mangosteen shell, rambutan shell, jackfruit shell, lychee shell, coconut shell, and passion fruit shell.

[0009] Preferably, in step b), a 5-15wt% water-soluble polymer solution is first prepared at 80-110°C using a liquid bath heating device, and then a porous biochar material and an acidic solution are added to the water-soluble polymer solution, wherein the porous biochar material accounts for 5-20wt% of the total amount of the water-soluble polymer solution, and the acidic solution accounts for 5-25wt% of the total amount of the water-soluble polymer solution. The solution is then heated in a liquid bath at 70-120°C for 1-6h to obtain a composite solution, and the composite solution is dried in an oven for 2-5h at a drying temperature of 40-70°C. After drying, the electrode material is obtained, and the bath liquid is water or oil.

[0010] Preferably, the water-soluble high molecular polymer is one or a combination of polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone or polyethyleneimine, and the acidic solution is one or a combination of sulfuric acid solution, hydrochloric acid solution, phosphoric acid solution, acetic acid solution or nitric acid solution.

[0011] Preferably, in step c), the organosilicon polymer is polydimethylsiloxane, polyphenylsiloxane, polymethylphenylsiloxane, polymethylsiloxane or polyvinylsiloxane; the polar solvent is one or a combination of deionized water, ethanol, acetic acid, acetone, methanol, ethyl acetate; and the volume ratio of the organosilicon polymer to the polar solvent is (3-7):1.

[0012] Preferably, after the organosilicon polymer and the polar solvent are poured into a mold, they are mechanically stirred at a rotation speed of 200-600 rpm for 0.2-2 hours, and then placed in an oven for drying for 0.2-2 hours, and the solidified product is the friction layer.

[0013] Preferably, in step c), the friction nanogenerator has a sandwich structure, wherein the middle layer is the electrode material, and the upper and lower layers are friction layers; during production, the lower friction layer is first produced in a mold, then the electrode material of the middle layer is poured and solidified, and finally the upper friction layer is poured and solidified to ensure that the middle electrode is not separated from the friction layers on both sides, and during the production process, a copper foil is attached to the edge of the electrode as a wire connected to the external circuit.

[0014] Preferably, the thickness of the electrode material is 0.5-3 mm; the thickness of the friction layer is 0.5-3 mm; and the area of ​​the electrode material is smaller than that of the friction layer.

[0015] As a preferred method, the porous biochar material made from tropical fruit shells is used as the electrode material of TENG, and is used in the energy collection and self-powered sensing field of TENG. Taking the energy collection field of TENG as an example, the TENG can collect the mechanical energy generated by the human body, and its output voltage is not less than 500V, the output current is not less than 5μA, and the power density is not less than 0.5W / m 2 Taking the self-powered sensing field of TENG as an example, the TENG can be further applied to human motion monitoring and gesture recognition by detecting different voltages generated in different parts of the human body.

[0016] Beneficial effects of the present invention: 1. The present invention adopts porous biochar material as the matrix. Different from the traditional carbon materials such as graphene and fullerene, which have complex preparation process and high cost, the use of tropical fruit shell as raw material to prepare carbon materials can effectively utilize resources, reduce environmental burden, and reduce the cost of preparing TENG, thus providing a low-cost energy solution. 2. The present invention achieves high electrochemical performance of carbon materials by using a low dose of activating agent. The rich pore structure in the porous biochar material can provide a larger surface area and better ion transmission performance, thereby improving the electrical output performance of TENG. The output voltage and current after activation are at least 1.4 times that before activation. 3. The present invention uses cheap biomass raw materials and other materials to prepare TENG with excellent output performance and strong durability in simple steps, which is very cost-effective; 4. The TENG of the present invention can achieve an output voltage of not less than 500V, an output current of not less than 5μA, and an output current of not less than 0.5W / m 2 The power density can not only solve the disposal problem of fruit shell waste, but also expand the application of biochar in energy collection, which has dual significance for energy and environment.

[0017] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of the method of the present invention; Figure 2 is the SEM image of the biochar before and after activation of Example 1; Figure 3 is a physical picture of the TENG in Example 1; Figure 4 is a side view of the output voltage, current and maximum power density of TENG at different impact frequencies in Example 1; Figure 5 is a comparison diagram of the output voltage and current of Example 1 before and after activation; Figure 6 is a schematic diagram of embodiment 1 for charging a commercial capacitor and supplying power to a commercial calculator and an electronic clock; Figure 7 It is a schematic diagram of different voltage waveforms and magnitudes generated by collision and striking of different parts of the human body in the first embodiment. DETAILED DESCRIPTION

[0019] Embodiment 1: See also Figure 1 , the flexible electrodes made of biomass-derived carbon materials were applied to TENG and tested. The specific steps are as follows: Step 1: Use mangosteen shell as waste biomass, rinse its surface with deionized water, and dry it in an oven at 110°C for 24h; then, take it out, crush it, sieve it, and take mangosteen shell powder below 60 mesh for subsequent experiments. Weigh 9g of mangosteen shell powder, add 1g of potassium carbonate for mechanical mixing, and then place them together in a tubular furnace at 750°C for high-temperature pyrolysis. After cooling, wash it several times with hydrochloric acid and deionized water, and dry it to obtain a porous biochar material ( Figure 2 The specific surface area of ​​the activated porous biochar material was measured to be 951 m 2 / g, the specific surface area of ​​the porous biochar material without adding activator was 108m 2 / g.

[0020] Step 2: Add 15wt% of the porous biochar material based on the total amount of the polyvinyl alcohol solution and 15wt% of the phosphoric acid solution (concentration of 85wt%) based on the total amount of the polyvinyl alcohol solution to the prepared 10wt% polyvinyl alcohol solution, heat in a water bath at 95°C and stir for 3h to obtain a composite solution.

[0021] Step 3: After the polydimethylsiloxane (PDMS) prepolymer and curing agent (Dow Corning 184 Sylgard 184PDMS) are uniformly mixed at a mass ratio of 10:1, they are poured into the mold with deionized water at a volume ratio of 5:1 and stirred evenly for 30 minutes. Then, they are placed in an oven and dried at 70°C until solid. Then, the composite solution is poured into the mold and placed in an oven and dried at 50°C for 3 hours. After the composite solution is dried, it becomes the electrode material. Finally, the treated PDMS solution is poured into the mold according to the above steps, and the mixture is placed in an oven and dried until solid. The thickness of the friction layer and the electrode is controlled to be 1 mm. The cured material is TENG, as shown in FIG. Figure 3 As shown, the prepared TENG is flexible, can be bent and folded arbitrarily, and is small and easy to carry.

[0022] Step 4: The prepared TENG is installed on the linear motor with an impact frequency of 1-7 Hz to explore the effect of different frequencies on the output voltage of the TENG, such as Figure 4 As shown, the open circuit voltage of 758V, the short circuit current of 10.07μA and the 2 The power density, such as Figure 5 As shown, at an impact frequency of 4 Hz, the output voltage and current of the TENG made of activated biochar are 1.48 and 1.46 times of those of the TENG made of unactivated biochar, respectively.

[0023] Step 5: The TENG can be used to charge commercial capacitors of different capacities and can be used to power commercial calculators and electronic clocks ( Figure 6 ), hitting the TENG with different parts of the human body can also generate different voltage waveforms and outputs, which can be used for human motion detection ( Figure 7 ).

[0024] Embodiment 2: Mangosteen shells were used as waste biomass, and 7 wt % phosphoric acid solution was added when preparing electrode materials. Other aspects were the same as those in Example 1.

[0025] In addition, the TENG obtained in this embodiment measured an open circuit voltage of 613 V, a short circuit current of 7.27 μA and a power consumption of 0.65 W / m under the same test conditions. 2 The power density of the activated biochar TENG is 1.4 and 1.41 times higher than that of the unactivated biochar TENG, respectively. In practical applications, it can also realize the application of energy harvesting and self-powered sensing.

[0026] The biggest difference between Example 2 and Example 1 is that the content of the phosphoric acid solution is reduced, the flexibility of the electrode is reduced after drying, and the electrical output performance of TENG is slightly reduced.

[0027] Embodiment three: Step 1: Rambutan shells were used as waste biomass, and its specific surface area was measured to be 1067 m 2 / g; the rest is the same as in Example 1.

[0028] In addition, the TENG obtained in this embodiment measured an open circuit voltage of 807 V, a short circuit current of 10.56 μA and a power consumption of 1.2 W / m 2 The power density of the activated biochar TENG is 1.51 and 1.56 times higher than that of the unactivated biochar TENG, respectively. In practical applications, it can also realize the application of energy harvesting and self-powered sensing.

[0029] The biggest difference between Example 3 and Example 1 is that the fruit shells used are from different sources, the specific surface area of ​​the biochar is increased, and the electrical output performance of TENG is slightly enhanced.

[0030] Embodiment 4: Rambutan shells were used as waste biomass; 14 wt% of biomass carbon material was added when preparing the electrode material; the rest was the same as in Example 1.

[0031] In addition, the TENG obtained in this embodiment measured an open circuit voltage of 636 V, a short circuit current of 5.01 μA and a power consumption of 0.58 W / m under the same test conditions. 2 The power density of the TENG made of activated biochar is 1.47 and 1.41 times that of the TENG made of unactivated biochar, respectively. In practical applications, it can also realize the application of energy harvesting and self-powered sensing.

[0032] The biggest difference between Example 4 and Example 3 is that the amount of biochar added when making the electrode material increases, which leads to the weakening of the electrode conductivity and mechanical strength, and the electrical output performance of TENG is greatly reduced, and the sensitivity is also reduced accordingly.

[0033] Embodiment five: Durian shell was used as waste biomass, and its specific surface area was measured to be 924m 2 / g, and when preparing the PDMS solution, the ratio of PDMS to deionized water is 3:1; the rest is the same as in Example 1.

[0034] In addition, the TENG obtained in this embodiment measured an open circuit voltage of 546 V, a short circuit current of 5.14 μA and a power consumption of 0.53 W / m under the same test conditions. 2 The power density of the TENG made of activated biochar is 1.52 and 1.48 times that of the TENG made of unactivated biochar, respectively. In practical applications, it can also realize the application of energy harvesting and self-powered sensing.

[0035] The biggest difference between Example 5 and Example 1 is that the ratio of PDMS to polar solvent is reduced, the actual contact area of ​​the friction layer is reduced, and the electrical output performance of TENG is greatly reduced.

[0036] Embodiment six: Durian shell was used as waste biomass, and its specific surface area was measured to be 924m 2 / g, and the polar solvent added in the preparation of the polyvinyl alcohol solution is ethanol; the rest is the same as in Example 5.

[0037] In addition, the TENG obtained in this embodiment measured an open circuit voltage of 518 V, a short circuit current of 5.18 μA and a power consumption of 0.51 W / m 2The power density of the TENG made of activated biochar is 1.54 and 1.51 times that of the TENG made of unactivated biochar, respectively. In practical applications, it can also realize the application of energy harvesting and self-powered sensing.

[0038] The biggest difference between Example 6 and Example 5 is that the polar solvent added when preparing the polyvinyl alcohol solution is ethanol, and the electrical output performance of TENG is slightly reduced.

[0039] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. A method for preparing triboelectric nanogenerator electrodes based on tropical fruit shell-derived carbon, characterized in that: The steps include: a) Pyrolysis: After the discarded tropical fruit shells are uniformly mixed with a low proportion of activating agent, pyrolysis carbonization is carried out by controlling the heating rate and pyrolysis atmosphere, and then the activating agent is removed by acid washing to obtain a porous biochar material; b) Electrode preparation: using the porous biochar material prepared in step a) as a matrix, mixing the prepared water-soluble polymer solution with the porous biochar material and the acid solution in a certain proportion, and then heating the mixture in a liquid bath to prepare a composite solution, which is then placed in an oven for drying to obtain an electrode material; c) Preparation of friction nanogenerator: The electrode material prepared in step b) is encapsulated with an organic silicon polymer added with a polar solvent.

2. A method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 1, characterized in that: In step a), the mass mixing ratio of the activator to the tropical fruit shell is not higher than 25%; the activator is one or a combination of potassium hydroxide, zinc chloride, sodium bicarbonate, sodium carbonate, potassium carbonate, potassium bicarbonate, ethylenediamine phosphate, propylenediamine phosphate, ammonium sulfate, ammonium chloride, ammonium hydroxide, sodium fluorosilicate or ferrous sulfate; the heating rate is 5-15°C / min; the pyrolysis atmosphere is CO2; the final pyrolysis temperature is 650-950°C, and the pyrolysis time is 0.2-2h.

3. The method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 1, characterized in that: In step a), the tropical fruit shell has high lignin content greater than 20%, and is one or a combination of several of the following: durian shell, mangosteen shell, rambutan shell, jackfruit shell, lychee shell, coconut shell, and passion fruit shell.

4. The method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 1, characterized in that: In step b), a 5-15wt% water-soluble polymer solution is first prepared at 80-110°C using a liquid bath heating device, and then a porous biochar material and an acidic solution are added to the water-soluble polymer solution, wherein the porous biochar material accounts for 5-20wt% of the total amount of the water-soluble polymer solution, and the acidic solution accounts for 5-25wt% of the total amount of the water-soluble polymer solution. The solution is then heated in a liquid bath at 70-120°C for 1-6h to obtain a composite solution, and the composite solution is dried in an oven for 2-5h at a drying temperature of 40-70°C. After drying, the composite solution is the electrode material, and the bath liquid is water or oil.

5. A method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon as claimed in claim 4, characterized in that: The water-soluble high molecular polymer is one or a combination of polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone or polyethyleneimine, and the acidic solution is one or a combination of sulfuric acid solution, hydrochloric acid solution, phosphoric acid solution, acetic acid solution or nitric acid solution.

6. The method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 1, characterized in that: In step c), the organosilicon polymer is polydimethylsiloxane, polyphenylsiloxane, polymethylphenylsiloxane, polymethylsiloxane or polyvinylsiloxane; the polar solvent is one or a combination of deionized water, ethanol, acetic acid, acetone, methanol, and ethyl acetate; the volume ratio of the organosilicon polymer to the polar solvent is (3-7):

1.

7. A method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 6, characterized in that: After the organosilicon polymer and the polar solvent are poured into a mold, they are mechanically stirred at a rotation speed of 200-600 rpm for 0.2-2 hours, and then placed in an oven for drying for 0.2-2 hours. The solidified product is the friction layer.

8. The method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 6, characterized in that: In step c), the friction nanogenerator has a sandwich structure, in which the middle layer is the electrode material and the upper and lower layers are friction layers; during production, the lower friction layer is first produced in a mold, then the electrode material of the middle layer is poured and solidified, and finally the upper friction layer is poured and solidified to ensure that the middle electrode is not separated from the friction layers on both sides. During the production process, a copper foil is attached to the edge of the electrode as a wire connected to the external circuit.

9. A method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 8, characterized in that: The thickness of the electrode material is 0.5-3 mm; the thickness of the friction layer is 0.5-3 mm; the area of ​​the electrode material is smaller than that of the friction layer.

10. The method for preparing a triboelectric nanogenerator electrode based on tropical fruit shell-derived carbon according to claim 8, characterized in that: The triboelectric nanogenerator is applied in energy harvesting and self-powered sensing.

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