A nano-friction paper-based positive electrode material with an interpenetrating network structure and a preparation method thereof

Abstract

The present invention relates to the interdisciplinary technical field of special papermaking, carbon fiber-based materials, and sensor material preparation, and specifically relates to a nano-friction paper-based positive electrode material with an interpenetrating network structure and a preparation method thereof. The present invention uses aramid fibrils as a basic skeleton, aramid pulp as an auxiliary molding material, and a carboxymethyl cellulose dispersion for surface enhancement and triboelectric strengthening, thereby preparing the paper-based positive electrode material. This process effectively solves the problem of weak and easily distorted nano-friction signals caused by external electromagnetic, vibration, and other interference, and improves the measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the cross-technical field of special papermaking, carbon fiber-based materials and sensor material preparation, and specifically relates to a nano-friction paper-based positive electrode material with an interpenetrating network structure and a preparation method thereof. Background Art

[0002] Against the backdrop of the continuous development and integration of modern materials science and electronic technology, the field of flexible electronic devices has attracted considerable attention. Paper-based materials, due to their low cost, widespread availability, biodegradability, and naturally good flexibility, have become a promising candidate for substrate materials for flexible electronic devices. Triboelectric charging and charge transfer processes are crucial to the working principles of many flexible electronic devices. For example, in devices such as triboelectric nanogenerators, materials must be able to uniformly generate triboelectric charges and construct effective current transmission paths to achieve efficient power conversion and transmission. However, the inherent properties of paper-based materials lead to significant deficiencies in both of these aspects. Their complex and uneven surface microstructure and irregular distribution of chemical composition make it difficult to uniformly generate triboelectric charges across the entire material surface during friction. Furthermore, the sensing cathode material has a weak ability to transfer the generated charges, significantly limiting the further expansion and performance improvement of triboelectric-related applications of paper-based materials in the field of flexible electronic devices.

[0003] Paper-based triboelectric nanogenerators have seen continuous development in recent years. CN113644841A fabricated a folded, double-helix, multilayered paper-based triboelectric nanogenerator. CN118610691B prepared a meta-aramid-polyvinylidene fluoride (PVDF) composite nanofiber lithium battery separator by dispersing, stirring, and electrospinning meta-aramid and polyvinylidene fluoride (PVDF) electrospinning solutions. The separator adaptively adjusts the voltage and flow rate of the electrospinning device. CN114938156 A assembled an ion gel, prepared by uniformly mixing ethyl acrylate, a crosslinker, an initiator, and a solvent, into an electrode layer, a threaded silicone tube into a negative friction layer, and a non-woven aramid fabric into a positive friction layer. The resulting triboelectric nanogenerator is helically wrapped around the ion gel electrode and the threaded silicone tube into a negative friction layer wrapped around the non-woven aramid fabric. However, the current weak transfer capability of the sensing cathode material for generated charge has limited the development of nano-triboelectric power generation and nano-triboelectric sensing in China. Summary of the Invention

[0004] In response to the problems in the prior art that using paper-based materials as sensing positive electrode materials is difficult to uniformly generate friction charges and has insufficient effective current transmission paths, the present invention provides a nano-friction paper-based positive electrode material with an interpenetrating network structure and a preparation method thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a nano-friction paper-based positive electrode material with an interpenetrating network structure comprises the following steps:

[0007] Step 1: placing aramid fiber precipitation in deionized water, soaking and decomposing the fiber to obtain aramid fiber precipitation slurry A;

[0008] Aramid pulp with large specific surface area, rich terminal groups and strong interweaving is prepared by twisting, beating and refining the waste aramid fibers to obtain aramid pulp B after delamination and dispersion.

[0009] Step 2: adding carbon fiber to aramid precipitation slurry A and aramid pulp slurry B in a certain proportion, and performing decomposition treatment to obtain mixed slurry C;

[0010] Step 3: The mixed slurry C is rapidly dehydrated, cold pressed, and vacuum dried to prepare carbon fiber composite paper D;

[0011] Step 4: impregnating the carbon fiber composite paper D in a carboxymethyl cellulose aqueous dispersion to obtain an optimized carbon fiber composite paper E;

[0012] Step 5: vacuum-dry and hot-press the optimized carbon fiber composite paper E to obtain a paper-based positive electrode material F.

[0013] Preferably, in step 1, in the preparation of aramid precipitation slurry A, the aramid fibrils are para-aramid fibers with a diameter of 5 to 10 μm;

[0014] During soaking, the concentration of deionized water is 0.8-1.1 g / L, the soaking time is 6-9 hours, and the indoor ambient temperature is 20-25°C;

[0015] During degassing, the speed is 20000~25000 rpm.

[0016] Preferably, in step 1, when preparing the aramid pulp slurry B, the waste aramid fibers are derived from aramid protective clothing and woven scraps in the production process;

[0017] When rolling, the feed rate is 40-50 kg / h;

[0018] During beating, the waste aramid fiber treatment concentration is 3% to 6%, and the beating time is 3 to 5 hours;

[0019] During refining, the refining pressure is 700~800Pa, the time is 0.5~1.0h, and the specific surface area of ​​aramid pulp is 10~12m 2 / g;

[0020] The decomposition time is 0.5 to 1.0 h, and the concentration of the aramid pulp slurry B after decomposition is 3% to 5% g / L.

[0021] Preferably, in step 2, the carbon fiber is pitch-based carbon fiber with a length of 5 to 6 mm, a diameter of 7 to 8 μm, and a conductivity of 10² to 10 4 S / cm.

[0022] Preferably, the absolute dry ratio of aramid precipitate, carbon fiber, and aramid pulp is (1.1-0.8) g: (0.21-0.22) g: (1.1-0.8) g, and the slurry concentration after mixing the three is 2.17-2.23 g / L;

[0023] During degassing, the number of revolutions is 25,000 to 30,000 rpm.

[0024] Preferably, in step 3, the slurry is homogenized 10 to 15 times before rapid dehydration, and the dehydration time is 1.0 to 2.0 seconds;

[0025] During cold pressing, absorbent felt is placed on the upper and lower sides of the dehydrated sample. The cold pressing pressure is 20-40 MPa and the time is 8-10 minutes.

[0026] During vacuum drying, the temperature is 90-100°C; the vacuum degree is 99.5-99.9 kPa; and the time is 8-10 minutes.

[0027] Preferably, in step 4, during the impregnation, the average molecular weight of the carboxymethyl cellulose is 6000 to 17000, the mass fraction of the carboxymethyl cellulose solution is 0.8 wt% to 1.0 wt%, and the impregnation time is 1 to 2 min.

[0028] Preferably, in step 5, during vacuum drying, the temperature is 90-100° C., the vacuum degree is 99.5-99.9 kPa, and the time is 8-10 min;

[0029] During hot pressing finishing, the temperature is 180-200°C, the time is 10-20 minutes, and the pressure is 13-15 MPa.

[0030] A paper-based positive electrode material obtained according to the method for preparing a nano-friction paper-based positive electrode material with an interpenetrating network structure.

[0031] A nano friction generator comprises a positive electrode made of the positive electrode material and a negative electrode made of a polytetrafluoroethylene film.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The method for preparing a nano-friction paper-based positive electrode material with an interpenetrating network structure of the present invention uses an interpenetrating network of carbon fibers, aramid precipitated fibers, and aramid pulp as a skeleton and carboxymethyl cellulose as a friction surface building agent to prepare a paper-based positive electrode material, thereby overcoming the problem that the nano-friction signal is weak and susceptible to interference, and external electromagnetic, vibration and other interferences may cause signal distortion, affecting the measurement accuracy and cannot be solved. On the one hand, aramid pulp fibers are introduced to improve the uniformity of paper and promote the interweaving of fiber networks. On the other hand, low-concentration carboxymethyl cellulose is used for impregnation and bonding to prevent the closure of the pore structure. In this structure, the molecular structure of the introduced aramid pulp is composed of alternating benzene rings and amide bonds, and the molecular structure has a high carbon content. Its high carbon content is conducive to the formation of a paper base with higher conductivity after carbonization treatment; at the same time, the dispersibility of the mixed pulp also helps to improve the uniformity of the base paper.

[0034] Aramid pulp not only exhibits excellent flexibility and adhesion but also enhances the flexibility and strength of paper during the papermaking process, compensating for the brittleness and interfacial inertness of carbon fibers. During carbonization, it forms a rich conductive network, optimizing the paper's electrical conductivity and achieving a balance between strength, toughness, and conductivity. Furthermore, the proportion of aramid pulp is determined through long-term process optimization. Excessive aramid pulp content hinders impregnation with carboxymethyl cellulose, while either excessively high or low proportions are detrimental to improving paper performance.

[0035] Based on the introduction of aramid pulp as an auxiliary, the adhesion and reinforcement of the interweaving points between carbon fibers, carbon fibers and aramid pulp, and aramid pulp are strengthened through the impregnation of ultra-low concentration carboxymethyl cellulose. The concentration of carboxymethyl cellulose is the result of process optimization. At ultra-low concentration, it not only supplements the insufficient fiber contact, but also facilitates the construction of the conductive network after carbonization, while ensuring strength and stress transfer during stretching. It not only supplements the insufficient fiber contact, but also facilitates the construction of the conductive network after carbonization, while ensuring strength and stress transfer during stretching.

[0036] The preferred aramid pulp terminal groups contain rich amino groups, have good compatibility and self-binding ability with carboxymethyl cellulose, and ensure high performance at low concentrations. The principle is that the aramid pulp terminal groups and carboxymethyl cellulose can form extensive hydrogen bonds, and the solidification of carboxymethyl cellulose can cross-link the pulp fiber filaments, achieving high-strength bonding through the combined action of chemistry and physics. This technical point has not been reported in other disclosed technologies of the present invention.

[0037] Furthermore, the pulp decomposition speed, fiber addition order, drying temperature, hot pressing finishing temperature and pressure are all the results of long-term process optimization. The optimization of these parameters helps to improve paper quality and save energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of a method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure according to the present invention;

[0039] Figure 2 This is a voltage diagram obtained by sensing the carbon fiber paper-based cathode material obtained in Example 1;

[0040] Figure 3 This is the current diagram obtained by the sensing application of the carbon fiber paper-based cathode material obtained in Example 1;

[0041] Figure 4 This is the charge diagram obtained from the sensing application of the carbon fiber paper-based cathode material obtained in Example 1;

[0042] Figure 5 is a SEM image of the surface of the carbon fiber paper-based positive electrode material obtained in Example 1;

[0043] Figure 6 This is the XRD performance test of carbon fiber paper-based positive electrode material in implementation case 1. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0045] The present invention discloses a method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure, referring to Figure 1 , including the following steps:

[0046] Step 1: placing the aramid fiber precipitate A in deionized water with a concentration of 0.8-1.1 g / L, soaking it at an indoor ambient temperature of 20-25° C. for 6-9 hours, and then dispersing it at a rotation speed of 20,000-25,000 rpm to obtain a uniformly dispersed aramid fiber precipitate slurry A.

[0047] Waste aramid fibers (derived from aramid protective clothing and woven scraps in the production process) are subjected to thread rolling, beating, and grinding to obtain aramid pulp with high specific surface area, high terminal bifurcation, and high interweaving strength. Aramid pulp slurry B is obtained after debonding and dispersion.

[0048] Among them, thread rolling is carried out using a thread rolling machine, the thread rolling machine model is TMF250, and the thread rolling machine feeding time is 40-50kg / h; beating uses a KDH100-XT beater, the meta-aramid fiber treatment beating concentration is 3%-6%, and the time is 3-5h; refining uses a FZ-102 refiner, the refining treatment pressure in the refiner is 700-800pa, the time is 0.5-1.0h, the obtained aramid pulp has a specific surface area of ​​10-12 m2 / g, a decomposition concentration is 3%-5% g / L, and the decomposition time is 0.5-1.0h.

[0049] Step 2: According to the absolute dry ratio of aramid precipitate, carbon fiber, and aramid pulp of (1.1-0.8) g: (0.21-0.22) g: (1.1-0.8) g, the three are mixed and dispersed at a speed of 25,000-30,000 rpm to obtain a mixed slurry C with a concentration of 2.17-2.23 g / L.

[0050] Step 3: The mixed slurry C is subjected to rapid dehydration, cold pressing, and vacuum drying to prepare carbon fiber composite paper D.

[0051] Among them, the carbon fiber is pitch-based carbon fiber with a length of 5 to 6 mm, a diameter of 7 to 8 μm., and an electrical conductivity of 10² to 10 4 S / cm; homogenize 10-15 times before rapid dehydration, with a dehydration time of 1.0-2.0 seconds. During cold pressing, place wool-based absorbent felt under the dehydrated sample, with a cold pressing pressure of 20-40 MPa and a time of 8-10 minutes. During vacuum drying, the temperature is 90-100°C, the vacuum level is 99.5-99.9 kPa, and the drying time is 8-10 minutes.

[0052] Step 4: Immersing the carbon fiber composite paper D in a carboxymethyl cellulose dispersion having a mass fraction of 0.8 wt% to 1.0 wt% of carboxymethyl cellulose for 1 to 2 minutes, wherein the average molecular weight of the carboxymethyl cellulose is 6000 to 17000;

[0053] Step 5: Drying and hot pressing are then performed to obtain the carbon nanofiber paper-based cathode material. The vacuum drying temperature is 90-100°C, the vacuum degree is 99.5-99.9 kPa, and the drying time is 8-10 minutes. The hot pressing finishing temperature is 180-200°C, the time is 10-20 minutes, and the pressure is 13-15 MPa.

[0054] The present invention discloses a method for preparing a nano-friction paper-based positive electrode material with an interpenetrating network structure. The method uses aramid fibrils as a basic skeleton, aramid pulp as an auxiliary molding material, and a carboxymethyl cellulose dispersion for surface enhancement and triboelectric strengthening, thereby preparing a paper-based positive electrode material. This process effectively solves the problem of weak and easily distorted nano-friction signals caused by external electromagnetic, vibration and other interference, and improves the measurement accuracy.

[0055] The deflaking machine, paper sheet former, dryer, hot press, etc. used in the preparation method proposed by the present invention are all conventional equipment. The process links are environmentally friendly, laying a good foundation for industrialization and scale-up, and having high market competitiveness.

[0056] The present invention also discloses a paper-based positive electrode material obtained according to the preparation method of the nano-friction paper-based positive electrode material with an interpenetrating network structure.

[0057] The present invention also discloses a nano-friction generator, comprising a positive electrode made of the above-mentioned positive electrode material and a negative electrode made of a polytetrafluoroethylene film. Specifically, the nano-friction generator is prepared as follows: a copper foil tape with a thickness of 18μm to 25μm is pasted on a positive electrode made of a carbon fiber paper-based positive electrode material F, and a wire is attached to it, and the positive electrode is rubbed and collided with a negative electrode made of a polytetrafluoroethylene film G with a thickness of 0.1 to 0.5mm and attached with the wire and the same copper foil tape for sensing application.

[0058] Example 1

[0059] Step 1: A aramid fibril with a dry weight of 0.88 g was placed in deionized water and soaked for 8 hours to obtain a uniformly dispersed aramid fibril slurry A. A aramid pulp with a large specific surface area, abundant ends, and strong interweaving was obtained by spinning, beating, and refining the waste aramid fibers. A aramid pulp slurry B was obtained after debonding and dispersion. The ratio of aramid pulp B to water was 1.1 g²: 2 L, and its dry weight was 1.1 g.

[0060] Step 2: 0.21 g of carbon fiber and aramid pulp dispersed slurry was added to the aramid precipitated fiber slurry, and the slurry was decomposed to form a mixed slurry C. The decomposition speed was 25000 rpm. Carbon fiber composite paper D was prepared by dehydration, cold pressing for 8 minutes, and vacuum drying. The drying vacuum degree was 99.5 kPa, the temperature was 105 ° C, the time was 8 minutes, the dried paper weight was 2.26 g, and the paper sheet thickness was 0.077 mm.

[0061] Step 3: Carbon fiber composite paper D was impregnated with a 0.8 wt% carboxymethyl cellulose aqueous dispersion, followed by drying and hot pressing. The drying process was performed at 60°C for 12 minutes, and the hot pressing process was performed at 200°C for 15 minutes at a pressure of 13 MPa. This resulted in a carbon fiber nanoparticle-based positive electrode material.

[0062] Step 4: A copper foil tape with a thickness of 18 μm is pasted on the carbon fiber paper-based positive electrode material E and a wire is attached. It is rubbed and impacted with a 0.1 mm thick polytetrafluoroethylene film F with a wire and the same copper foil tape for sensing application.

[0063] The carbon fiber paper-based positive electrode material based on the triboelectric principle obtained in Example 1 has a paper basis weight of 70 g / m2, a thickness of 0.077 mm, and a paper weight of 2.26 g. Figure 5, it can be clearly seen that the material has an inter-conductive grid structure. The carboxymethyl cellulose is mainly distributed on the surface of the aramid fibrils. The bond between the carbon fibers and the aramid fibrils with a filamentous structure is relatively strong. The reason for this is that the surface of the aramid fibrils is rich in many active groups. These groups enable the carbon fibers to be evenly dispersed and are tightly entangled by the aramid fibrils through physical interweaving, thereby effectively curbing the agglomeration of the carbon fibers and promoting their uniform dispersion in the composite system. Figure 6 At 26.57 degrees, stretching vibration of the carbon fiber can be observed, proving that the prepared carbon fiber paper-based cathode material meets the requirements. In sensing applications, the current can reach 74.58nA and the voltage can reach 10.50V at a frequency of 5Hz, generating a charge of 1.39nC, demonstrating efficient sensing performance.

[0064] Table 1 Sensing parameters of the carbon fiber paper-based cathode material based on the triboelectric principle prepared in Example 1 at friction rates of 3 Hz, 5 Hz, and 7 Hz

[0065]

[0066] Example 2

[0067] Step 1: A 1.09 g dry weight of aramid fibrils was placed in deionized water and soaked for 8 hours to obtain a uniformly dispersed aramid fibrils slurry A. A waste aramid fiber was subjected to spinning, beating, and refining to prepare a broom, thereby obtaining an aramid pulp with a large specific surface area, abundant ends, and strong interweaving. After debonding and dispersion, an aramid pulp slurry B was obtained, wherein the ratio of aramid pulp B to water was 0.87 g: 2 L, and its dry weight was 0.87 g.

[0068] Step 2: Add 0.22 g of carbon fiber and aramid pulp slurry to aramid precipitated fiber slurry, and decompress it to form a mixed slurry C. The decomposition speed is 30,000 rpm; carbon fiber composite paper D is prepared by dehydration, cold pressing for 8 minutes, and vacuum drying. During drying, the drying vacuum degree is 99.9 kPa, the temperature is 105°C, the time is 10 minutes, the dried paper weight is 2.25 g, and the paper sheet thickness is 0.104 mm.

[0069] Step 3: Carbon fiber composite paper D was impregnated with a carboxymethyl cellulose dispersion (0.9 wt%), followed by drying and hot pressing. The drying temperature was 70°C for 12 minutes, and the hot pressing temperature was 200°C for 14 minutes at a pressure of 13 MPa. Finally, a nanocarbon fiber paper-based cathode material was obtained.

[0070] Step 4: A 25 μm thick copper foil tape was pasted on the carbon fiber paper-based positive electrode material E and a wire was attached, and it was rubbed and collided with a 0.5 mm thick polytetrafluoroethylene film F with a wire and the same copper foil tape for sensing application.

[0071] The carbon fiber paper-based positive electrode material based on the triboelectric principle obtained in Example 2 has a paper basis weight of 70 g / m 2 , thickness is 0.104 mm, paper weight is 2.25g, in sensing applications, the current can reach 77.15nA at a frequency of 5HZ, the voltage can reach 10.79V, and the charge generated can reach 1.58nC, which has efficient sensing function.

[0072] Example 3

[0073] Step 1: A aramid fibril with a dry weight of 0.90 g was placed in deionized water and soaked for 8 hours to obtain a uniformly dispersed aramid fibril slurry A. A aramid pulp with a large specific surface area, abundant ends, and strong interweaving was obtained by spinning, beating, and refining the waste aramid fibers. Aramid pulp B was obtained after decomposition and dispersion. The ratio of aramid pulp B to water was 1.09 g: 2 L, and its dry weight was 1.09 g.

[0074] Step 2: Add 0.21 g of carbon fiber and aramid pulp slurry to aramid precipitated fiber slurry, and decompress it to form a mixed slurry C. The decomposition speed is 25,000 rpm; carbon fiber composite paper D is prepared by dehydration, cold pressing for 8 minutes, and vacuum drying. During drying, the drying vacuum degree is 99.6 kPa, the temperature is 105°C, the time is 8 minutes, the dried paper weight is 2.17 g, and the paper sheet thickness is 0.097 mm.

[0075] Step 3: Carbon fiber composite paper D was impregnated with a 0.8 wt% carboxymethyl cellulose aqueous dispersion, followed by drying and hot pressing. The drying temperature was 60°C for 10 minutes, and the hot pressing temperature was 200°C for 15 minutes at a pressure of 13 MPa. This resulted in a nanocarbon fiber paper-based cathode material.

[0076] Step 4: A 20 μm thick copper foil tape was pasted on the carbon fiber paper-based positive electrode material E and a wire was attached, and it was rubbed and collided with a 0.3 mm thick polytetrafluoroethylene film F with a wire and the same copper foil tape for sensing application.

[0077] The carbon fiber paper-based positive electrode material based on the triboelectric principle obtained in Example 3 has a basis weight of 70 g / m 2, thickness is 0.097 mm, paper weight is 2.17g, in sensing applications, the current can reach 76.52nA at a frequency of 5HZ, the voltage can reach 11.62V, and the charge generated can reach 1.47nC, which has efficient sensing function.

[0078] Example 4

[0079] Step 1: A 1.09 g dry weight of aramid fibrils was placed in deionized water and soaked for 8 hours to obtain a uniformly dispersed aramid fibrils slurry A. A waste aramid fiber was subjected to spinning, beating, and refining to prepare a broom, thereby obtaining an aramid pulp with a large specific surface area, abundant ends, and strong interweaving. After debonding and dispersion, an aramid pulp slurry B was obtained, wherein the ratio of aramid pulp B to water was 0.87 g: 2 L, and its dry weight was 0.87 g.

[0080] Step 2: Add 0.21 g of carbon fiber and aramid pulp slurry to aramid precipitated fiber slurry, and decompress it to form a mixed slurry C. The decomposition speed is 25,000 rpm; carbon fiber composite paper D is prepared by dehydration, cold pressing for 8 minutes, and vacuum drying. During drying, the drying vacuum degree is 99.7 kPa, the temperature is 105°C, the time is 8 minutes, the dried paper weight is 2.23 g, and the paper sheet thickness is 0.103 mm.

[0081] Step 3: Carbon fiber composite paper D was impregnated with a 0.9 wt% carboxymethyl cellulose aqueous dispersion, followed by drying and hot pressing. The drying temperature was 75°C for 12 minutes, and the hot pressing temperature was 200°C for 15 minutes at a pressure of 13 MPa. This resulted in a nanocarbon fiber paper-based cathode material.

[0082] Step 4: A 23 μm thick copper foil tape was pasted on the carbon fiber paper-based positive electrode material E and a wire was attached, and it was rubbed and collided with a 0.3 mm thick polytetrafluoroethylene film F with a wire and the same copper foil tape for sensing application.

[0083] The carbon fiber paper-based positive electrode material based on the triboelectric principle obtained in Example 4 has a basis weight of 70 g / m 2 , thickness is 0.103mm, paper weight is 2.23g, in sensing applications, the current can reach 72.48nA at a frequency of 5HZ, the voltage can reach 10.28V, and the charge generated can reach 1.24nC, which has efficient sensing function.

[0084] Example 5

[0085] Step 1: A aramid fibril with a dry weight of 0.88 g was placed in deionized water and soaked for 8 hours to obtain a uniformly dispersed aramid fibril slurry A. A aramid pulp with a large specific surface area, abundant ends, and strong interweaving was obtained by spinning, beating, and refining the waste aramid fibers. Aramid pulp B was obtained after decomposition and dispersion. The ratio of aramid pulp B to water was 1.1 g: 2 L, and its dry weight was 1.1 g.

[0086] Step 2: Add 0.21 g of carbon fiber and aramid pulp slurry to aramid precipitated fiber slurry, and perform decomposition treatment to form a mixed slurry C. The decomposition speed is 25,000 rpm. Carbon fiber composite paper D is prepared by dehydration, cold pressing for 8 minutes, and drying. During drying, the temperature is 100°C, the time is 10 minutes, the dried paper weight is 2.18 g, and the paper sheet thickness is 0.086 mm.

[0087] Step 3: Carbon fiber composite paper D is immersed in a carboxymethyl cellulose aqueous dispersion with a carboxymethyl cellulose mass fraction of 0.9 wt%, and then vacuum dried and hot pressed. During drying, the vacuum degree is 99.8 kPa, the temperature is 70 ° C, and the time is 12 min; during hot pressing finishing, the temperature is 200 ° C, the time is 15 min, and the pressure is 13 MPa. Finally, a nano-carbon fiber paper-based positive electrode material is obtained.

[0088] Step 4: A 21 μm thick copper foil tape was pasted on the carbon fiber paper-based positive electrode material E and a wire was attached, and it was rubbed and collided with a 0.2 mm thick polytetrafluoroethylene film F with a wire and the same copper foil tape for sensing application.

[0089] The carbon fiber paper-based positive electrode material based on the triboelectric principle obtained in Example 5 has a basis weight of 70 g / m 2 , thickness is 0.086mm, paper weight is 2.18g, in sensing applications, the current can reach 75.32nA at 5HZ frequency, the voltage can reach 11.25V, and the charge generated can reach 1.43nC, which has efficient sensing function.

[0090] Table 2 Technical parameters of carbon fiber paper-based cathode materials based on triboelectric charging principle prepared in Examples 1 to 5

[0091]

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and replacements, and these modifications and replacements are also within the scope of protection covered by the claims.

Claims

1. A method for preparing a nano-friction paper-based positive electrode material with an interpenetrating network structure, characterized in that: The following steps are involved: Step 1: placing aramid fiber precipitation in deionized water, soaking and decomposing the fiber to obtain aramid fiber precipitation slurry A; Aramid pulp with large specific surface area, rich terminal groups and strong interweaving is prepared by twisting, beating and refining the waste aramid fibers to obtain aramid pulp B after delamination and dispersion. Among them, the aramid fibrils are para-aramid fibers with a diameter of 5 to 10 μm; The specific surface area of ​​aramid pulp is 10-12 m 2 / g; Step 2: Add carbon fiber to aramid precipitation slurry A and aramid pulp slurry B in a certain proportion, and disintegrate to obtain mixed slurry C; the carbon fiber is pitch-based carbon fiber with a length of 5-6 mm, a diameter of 7-8 μm, and an electrical conductivity of 10 2 ~10 4 S / cm; Step 3: The mixed pulp C is rapidly dehydrated, cold-pressed, and vacuum-dried to prepare carbon fiber composite paper D. The absolute dry ratio of aramid precipitate, carbon fiber, and aramid pulp is (1.1-0.8) g: (0.21-0.22) g: (1.1-0.8) g, and the slurry concentration after mixing is 2.17-2.23 g / L. During the cold-pressing process, absorbent felt is placed on the upper and lower surfaces of the dehydrated sample. The cold-pressing pressure is 20-40 MPa, and the pressing time is 8-10 min. Step 4: Impregnating the carbon fiber composite paper D in a carboxymethyl cellulose aqueous dispersion to obtain an optimized carbon fiber composite paper E; during the impregnation, the average molecular weight of the carboxymethyl cellulose is 6000 to 17000, and the mass fraction of the carboxymethyl cellulose solution is 0.8 wt% to 1.0 wt%; Step 5: vacuum-dry and hot-press the optimized carbon fiber composite paper E to obtain a paper-based positive electrode material F; during hot-pressing finishing, the temperature is 180-200° C., the time is 10-20 min, and the pressure is 13-15 MPa.

2. The method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure according to claim 1, characterized in that: In step 1, aramid precipitation slurry A is prepared, and during soaking, the concentration of deionized water is 0.8-1.1 g / L, the time is 6-9 hours, and the indoor ambient temperature is 20-25°C; During degassing, the speed is 20000~25000 rpm.

3. The method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure according to claim 1, characterized in that: In step 1, when preparing aramid pulp slurry B, the waste aramid fibers are derived from aramid protective clothing and woven scraps in the production process; When rolling, the feed rate is 40-50 kg / h; During beating, the waste aramid fiber treatment concentration is 3% to 6%, and the beating time is 3 to 5 hours; During refining, the refining pressure is 700~800Pa and the time is 0.5~1.0h; The concentration of the aramid pulp B after deflaking is 3% to 5% g / L, and the deflaking time is 0.5 to 1.0 h.

4. The method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure according to claim 1, characterized in that: In step 2, during degassing, the number of revolutions is 25,000 to 30,000 rpm.

5. The method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure according to claim 1, characterized in that: In step 3, homogenize 10 to 15 times before rapid dehydration, and the dehydration time is 1.0 to 2.0 seconds; During vacuum drying, the temperature is 90-100°C; the vacuum degree is 99.5-99.9 kPa; and the time is 8-10 minutes.

6. The method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure according to claim 1, characterized in that: Step 4: The soaking time is 1 to 2 minutes.

7. The method for preparing a nano-friction paper-based positive electrode material having an interpenetrating network structure according to claim 1, characterized in that: In step 5, during vacuum drying, the temperature is 90-100° C., the vacuum degree is 99.5-99.9 kPa, and the time is 8-10 minutes.

8. A paper-based positive electrode material obtained by the method for preparing a nano-friction paper-based positive electrode material with an interpenetrating network structure according to any one of claims 1 to 7.

9. A nano-friction generator, characterized in that: It comprises a positive electrode made of the positive electrode material according to claim 8 and a negative electrode made of a polytetrafluoroethylene film.

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