Structural energy storage integrated carbon fiber composite material and preparation method thereof

Abstract

The invention provides a structural energy storage integrated carbon fiber composite material and a preparation method thereof, and belongs to the technical field of composite materials. The carbon fiber composite material comprises a carbon fiber-metal integrated energy storage battery cell and skins on the two sides of the carbon fiber-metal integrated energy storage battery cell, the carbon fiber-metal integrated energy storage cell comprises a positive electrode, a diaphragm, a negative electrode and a composite porous epoxy resin-based solid electrolyte; the composite porous epoxy resin-based solid electrolyte comprises composite porous epoxy resin and an ionic liquid electrolyte in the composite porous epoxy resin. The composite porous epoxy resin is prepared from the composite resin precursor, so that the mechanical strength, toughness, heat resistance and ion conductivity of the epoxy resin can be improved, and the comprehensive performance of the carbon fiber composite material can be improved. According to the structural energy storage integrated carbon fiber composite material prepared by the invention, the electrochemical energy storage capability is remarkably improved while the strength and the rigidity are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a structural energy storage integrated carbon fiber composite material and a preparation method thereof. Background Art

[0002] Structural energy storage composites are multifunctional materials capable of simultaneously carrying mechanical loads and storing electrical energy. They have been extensively researched for reducing the weight of equipment systems, with potential applications in electric vehicles, electric drones, electric vertical take-off and landing (eVTOL) vehicles, marine equipment, mobile robots, and wearable sensors. Transforming structural components with a single load-bearing function into multifunctional components that also have energy storage capabilities can achieve overall lightweighting, significantly improving load capacity, flight time, and range of application.

[0003] Currently, most research on structural energy storage composites focuses on embedding lithium-ion batteries into load-bearing structures or integrating lithium batteries into fiber composites. However, the energy density of structural batteries based on lithium ions embedded in polymer matrices is significantly lower than that of traditional stand-alone lithium-ion batteries. In addition, the interfacial bonding stability of the components of traditional structural energy storage composites is poor, and resin-based solid electrolytes have difficulty in achieving both excellent mechanical and electrochemical properties, often resulting in sacrificing mechanical properties while improving energy storage performance, and vice versa. This difficulty in balancing mechanical and energy storage performance limits the application of structural energy storage composites in practical engineering.

[0004] To address these shortcomings, a new technical solution is needed to improve the energy storage performance of structural composite materials while maintaining their mechanical properties, and to improve the interfacial bonding stability between the functional components. For example, existing carbon fiber composite materials typically use resin-based solid electrolyte systems, which have limited electrochemical performance due to limited ionic conductivity and poor interfacial compatibility. Therefore, it is necessary to innovate in material systems and configurations to achieve synergistic optimization of the mechanical and electrochemical properties of structural energy storage composite materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a structural energy storage integrated carbon fiber composite material and a preparation method thereof, so as to solve the problem in the prior art that structural energy storage composite materials are difficult to balance in terms of mechanical properties and energy storage performance.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a structural energy storage integrated carbon fiber composite material, the carbon fiber composite material comprising a carbon fiber-metal integrated energy storage battery core and skins on both sides of the carbon fiber-metal integrated energy storage battery core;

[0008] The carbon fiber-metal integrated energy storage battery core includes a positive electrode, a separator, a negative electrode and a composite porous epoxy resin-based solid electrolyte; the composite porous epoxy resin-based solid electrolyte includes a composite porous epoxy resin and an ionic liquid electrolyte inside the composite porous epoxy resin.

[0009] Preferably, the positive electrode is carbon-based material modified carbon fiber; the separator is glass fiber fabric; and the negative electrode is aluminum mesh, copper foil, nickel mesh, titanium foil or stainless steel metal mesh.

[0010] Preferably, the positive electrode, separator and negative electrode are composited into an integrated structure with the composite porous epoxy resin as a matrix.

[0011] Preferably, the carbon-based material modified carbon fiber includes carbon fiber and a carbon-based active material coated on the surface of the carbon fiber.

[0012] Preferably, the ionic liquid electrolyte comprises anhydrous aluminum chloride-1-ethyl-3-methylimidazolium chloride, anhydrous aluminum chloride-1-butyl-3-methylimidazolium chloride, anhydrous aluminum chloride-1-ethyl-3-methylimidazolium bromide, anhydrous aluminum chloride-1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and bis(trifluoromethanesulfonyl)imide lithium / 1-butyl-3-methylimidazolium tetrafluoroborate.

[0013] The present invention also provides a method for preparing the above-mentioned structural energy storage integrated carbon fiber composite material, comprising the following steps:

[0014] S1: pretreating carbon fibers to obtain pretreated carbon fibers, then coating the pretreated carbon fibers with a carbon-based slurry, and drying the pretreated carbon fibers to obtain carbon-based material-modified carbon fibers;

[0015] S2: pre-treating the negative electrode material to obtain a pre-treated negative electrode;

[0016] S3: stacking carbon-based material modified carbon fiber, glass fiber fabric, and pretreated negative electrode in sequence, then infusing composite resin precursor by vacuum infusion method, and curing to obtain a solid laminate;

[0017] S4: soaking and drying the solid laminate, and then impregnating it with an ionic liquid electrolyte to obtain a carbon fiber-metal integrated energy storage battery cell;

[0018] S5: Pasting skins on both sides of the carbon fiber-metal integrated energy storage battery cell to obtain a carbon fiber composite material.

[0019] Preferably, in step (1), the carbon-based slurry is made of expanded graphite powder, polyvinylidene fluoride and a solvent.

[0020] Preferably, in step (3), the composite resin precursor is made of a composite epoxy resin, a pore-forming agent and a curing agent; and the mass ratio of the composite epoxy resin to the pore-forming agent is 1:1 to 3.

[0021] Preferably, the composite epoxy resin comprises two or more of bisphenol A epoxy resin, bisphenol F epoxy resin, low-viscosity phenol formaldehyde varnish epoxy resin, difunctional glycidylamine epoxy resin and alicyclic epoxy resin.

[0022] Preferably, the pore-forming agent comprises one or more of polyethylene glycol, polypropylene glycol, sodium chloride crystals and urea; and the curing agent comprises two or more of 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodiphenylmethane, isophoronediamine, m-xylenediamine and 1,3-cyclohexanedimethylamine.

[0023] Beneficial effects of the present invention:

[0024] The present invention adopts a composite resin precursor to prepare a composite porous epoxy resin, which can improve the mechanical strength, toughness, heat resistance and ion conductivity of the epoxy resin, and is beneficial to improving the comprehensive performance of the carbon fiber composite material.

[0025] The structural energy storage integrated carbon fiber composite material prepared by the present invention significantly improves the electrochemical energy storage capacity while ensuring strength and rigidity.

[0026] The present invention uses copper foil as the negative electrode to further reduce internal resistance and improve interface stability, thereby maintaining high coulombic efficiency and stable capacity during cyclic charge and discharge, and having both excellent electrical and mechanical properties.

[0027] The structural energy storage integrated carbon fiber composite material of the present invention can simultaneously meet the strict requirements of mechanical properties and energy density in applications such as drones, eVTOL aircraft and automotive components. DETAILED DESCRIPTION

[0028] The present invention provides a structural energy storage integrated carbon fiber composite material, the carbon fiber composite material comprising a carbon fiber-metal integrated energy storage battery core and skins on both sides of the carbon fiber-metal integrated energy storage battery core;

[0029] The carbon fiber-metal integrated energy storage battery core includes a positive electrode, a separator, a negative electrode and a composite porous epoxy resin-based solid electrolyte; the composite porous epoxy resin-based solid electrolyte includes a composite porous epoxy resin and an ionic liquid electrolyte inside the composite porous epoxy resin.

[0030] In the present invention, the positive electrode is carbon-based material modified carbon fiber; the separator is glass fiber fabric; and the negative electrode is aluminum mesh, copper foil, nickel mesh, titanium foil or stainless steel metal mesh.

[0031] In the present invention, the positive electrode, the separator and the negative electrode are composited into an integrated structure with the composite porous epoxy resin as a matrix.

[0032] In the present invention, the carbon-based material modified carbon fiber includes carbon fiber and a carbon-based active material coated on the surface of the carbon fiber.

[0033] In the present invention, the ionic liquid electrolyte comprises anhydrous aluminum chloride-1-ethyl-3-methylimidazolium chloride, anhydrous aluminum chloride-1-butyl-3-methylimidazolium chloride, anhydrous aluminum chloride-1-ethyl-3-methylimidazolium bromide, anhydrous aluminum chloride-1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and bis(trifluoromethanesulfonyl)imide lithium / 1-butyl-3-methylimidazolium tetrafluoroborate.

[0034] The present invention also provides a method for preparing the above-mentioned structural energy storage integrated carbon fiber composite material, comprising the following steps:

[0035] S1: pretreating carbon fibers to obtain pretreated carbon fibers, then coating the pretreated carbon fibers with a carbon-based slurry, and drying the pretreated carbon fibers to obtain carbon-based material-modified carbon fibers;

[0036] S2: pre-treating the negative electrode material to obtain a pre-treated negative electrode;

[0037] S3: stacking carbon-based material modified carbon fiber, glass fiber fabric, and pretreated negative electrode in sequence, then infusing composite resin precursor by vacuum infusion method, and curing to obtain a solid laminate;

[0038] S4: soaking and drying the solid laminate, and then impregnating it with an ionic liquid electrolyte to obtain a carbon fiber-metal integrated energy storage battery cell;

[0039] S5: Pasting skins on both sides of the carbon fiber-metal integrated energy storage battery cell to obtain a carbon fiber composite material.

[0040] In the present invention, the specific steps of pre-treating the carbon fiber are: soaking the carbon fiber in acetone, taking it out and drying it, then placing it in a mixed acid solution for acidification, and finally washing and drying it to obtain pre-treated carbon fiber.

[0041] In the present invention, the soaking time is 1 to 3 hours, preferably 2 hours.

[0042] In the present invention, the mixed acid solution is prepared by mixing concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:1 to 3, preferably 1:1, 1:2, or 1:3.

[0043] In the present invention, in step (1), the carbon-based slurry is made of expanded graphite powder, polyvinylidene fluoride and a solvent.

[0044] In the present invention, the solvent is preferably N-methylpyrrolidone (NMP); and the mass ratio of the expanded graphite powder to polyvinylidene fluoride is preferably 9:1.

[0045] In the present invention, in step (3), the composite resin precursor is made of a composite epoxy resin, a pore-forming agent and a curing agent; the mass ratio of the composite epoxy resin to the pore-forming agent is 1:1 to 3, preferably 1:1, 1:2, or 1:3.

[0046] In the present invention, the composite epoxy resin comprises two or more of bisphenol A epoxy resin, bisphenol F epoxy resin, low-viscosity phenol formaldehyde varnish epoxy resin, difunctional glycidylamine type epoxy resin and alicyclic epoxy resin.

[0047] In the present invention, the pore-forming agent comprises one or more of polyethylene glycol, polypropylene glycol, sodium chloride crystals and urea; the curing agent comprises two or more of 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodiphenylmethane, isophoronediamine, m-xylenediamine and 1,3-cyclohexanedimethylamine.

[0048] In the present invention, the curing temperature is 80-150° C., and the curing time is 1-5 hours.

[0049] The structural energy storage integrated carbon fiber composite material prepared by the present invention has a continuous, interconnected ion-conducting network and a reinforced, interpenetrating multiphase structure formed within it: the carbon fiber reinforcement phase provides mechanical strength and a partial conductive path, the coated carbon-based active material provides a high-surface-area ion storage / charge exchange interface, the impregnated ionic liquid imparts ionic conductivity to the system, and the metal negative electrode provides a platform for reversible electrodeposition / embedding. The entire layered structure is bonded together by a composite porous epoxy resin matrix. This unique structure prevents relative slippage or delamination of the internal layers of the composite material when subjected to load, and allows ions to efficiently migrate between the positive and negative electrodes during electrochemical charge and discharge, thereby achieving both high mechanical properties and high energy storage performance.

[0050] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1

[0052] The carbon fiber (area density of 200g / m 2, size 100mm×100mm) was soaked in acetone for 2h, taken out, and dried at room temperature. After drying, it was placed in a mixed acid solution (mixed with concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3), heated to 60°C under ultrasonic conditions, and maintained for 30min to obtain pretreated carbon fiber; PVDF and expanded graphite powder were added to NMP solvent, wherein the mass ratio of expanded graphite powder (particle size range is 5-10μm) to PVDF was 9:1, and the ratio of the mass of NMP solvent to the mass sum of PVDF and expanded graphite powder was 4:1, and stirred for 8h to obtain carbon-based slurry; the pretreated carbon fiber was spread flat on a glass plate, and the carbon-based slurry was evenly coated on the surface of the pretreated carbon fiber by a doctor blade method, and the coating amount was 3.0mg·cm -2 After coating, the positive electrode was dried in a vacuum drying oven at 80°C for 12 h to obtain the positive electrode.

[0053] Immerse the aluminum mesh (industrial pure aluminum wire mesh, pore size 0.5 mm) in a 5% dilute hydrochloric acid solution for 10 minutes, take it out, rinse it with deionized water and dry it, and cut it into a rectangle with the same size as the above-mentioned carbon fiber (reserving 5 mm as the current collector) to obtain a pretreated aluminum mesh as the negative electrode.

[0054] The positive electrode, glass fiber fabric separator (thickness of 100 μm) and negative electrode are stacked in sequence in a mold, with the glass fiber fabric sandwiched between the positive and negative electrodes. The size of the glass fiber fabric separator is the same as that of the positive electrode.

[0055] Phenol formaldehyde varnish epoxy resin (epoxy equivalent 168 g / ep, viscosity 9000 mPa·s, Shandong Aimont New Materials Co., Ltd., brand EMTE625) and difunctional glycidylamine type epoxy resin (epoxy equivalent 125 g / ep, viscosity 50 mPa·s, Hubei Zhenzhenfeng New Materials Co., Ltd., brand MF-2133) were mixed in a mass ratio of 7:3, and the obtained mixed epoxy resin and PEG-200 were mixed and stirred in a mass ratio of 1:2 for 40 minutes. After mixing evenly, a mixed curing agent of 4,4'-diaminodicyclohexylmethane (HMDA) and 4,4'-diaminodiphenylmethane (DDM) (the mass ratio of HMDA and DDM was 7:3) was added, and the mass ratio of the mixed epoxy resin to the mixed curing agent was 100:33 (i.e., the stoichiometric ratio measured by epoxy equivalent), and continued stirring to obtain a composite resin precursor.

[0056] The mold is sealed and evacuated to a vacuum degree of -0.08MPa. The composite resin precursor is introduced into the mold by vacuum infusion to ensure that the composite resin precursor completely infiltrates all layers. After sealing the mold, it is placed in an oven for curing, first at 120°C for 2h, then heated to 150°C and cured for another 2h to obtain a solid laminate. The epoxy resin bonds the three-layer structure into one. The solid laminate is soaked in deionized water for 24h, taken out and dried in a vacuum oven at 60°C for 24h, and then soaked in anhydrous aluminum chloride-1-ethyl-3-methylimidazolium chloride ionic liquid electrolyte (the mass ratio of anhydrous aluminum chloride and 1-ethyl-3-methylimidazolium chloride is 1.4:1) for 24h to obtain a carbon fiber-aluminum integrated energy storage battery.

[0057] The carbon fiber-aluminum integrated energy storage battery cell prepared above was placed in a glove box, covered with carbon fiber fibers pre-impregnated with epoxy resin, and the skin was attached by hand lay-up process. Finally, it was placed in a vacuum drying oven and cured at 80°C for 3 hours to obtain a carbon fiber composite material with a size of 100mm×100mm and a thickness of 2mm (including the skins on both sides, and the thickness of the skins on both sides was 0.3mm).

[0058] The electrochemical test was carried out in a two-electrode fixture at room temperature with a test voltage window of 0.5 to 2.4 V. At a current density of 5 mA / g (relative to the mass of the positive electrode activated carbon material), the area specific capacitance and capacity of the carbon fiber composite material remained good, with an energy density of 50 Wh / kg (calculated based on the total mass of the entire carbon fiber composite material). When the discharge rate was increased to 50 mA / g, the carbon fiber composite material was still able to maintain a power density output of approximately 300 W / kg. The cycle life test showed that the coulombic efficiency of the carbon fiber composite material was stable at 90% after 100 cycles, showing good cycle stability.

[0059] Mechanical properties testing used the short beam method (performed in accordance with ASTM D2344) to test interlaminar shear strength, with a result of 22.5 MPa. Three-point bending tests revealed a flexural modulus of 30 GPa and a flexural strength of 400 MPa for the carbon fiber composite, demonstrating its excellent overall stiffness and strength.

[0060] The above results show that the carbon fiber composite material prepared in this embodiment has considerable mechanical properties while achieving energy storage function, and its energy density is significantly improved compared with traditional structural composite materials.

[0061] Example 2

[0062] The difference from Example 1 is that the aluminum mesh is replaced by copper foil, the thickness of the copper foil is 50 μm, and the pretreatment method of the copper foil is: soaking the copper foil in a 0.5 mol / L dilute sulfuric acid solution for 5 min, taking it out and wiping it clean with alcohol and blowing it dry; the pore-forming agent is PEG-400, in which epoxy resin and PEG-400 are mixed in a mass ratio of 1:1.8; the ionic liquid is 1-butyl-3-methylimidazolium chloride (the mass ratio of anhydrous aluminum chloride and 1-butyl-3-methylimidazolium chloride is 1.4:1), and other conditions are the same.

[0063] The electrochemical test was carried out in a two-electrode fixture at room temperature. The test voltage window was 0.5 to 2.4 V. At a current density of 5 mA / g (relative to the mass of the positive electrode activated carbon material), the area specific capacitance and capacity of the carbon fiber composite material remained good, and the energy density was 48 Wh / kg (calculated based on the total mass of the entire carbon fiber composite material). When the discharge rate was increased to 50 mA / g, the carbon fiber composite material was still able to maintain a power density output of about 350 W / kg. The cycle life test showed that the coulombic efficiency of the carbon fiber composite material was stable at 95% after 100 cycles, which was higher than that of Example 1. This shows that the interface of copper foil as the negative electrode is more stable during repeated charge and discharge, with fewer side reactions and better cycle performance.

[0064] Mechanical properties were tested using the short beam method (performed in accordance with ASTM D2344) to measure interlaminar shear strength, resulting in a value of 20 MPa, slightly lower than that of Example 1. This is attributed to the limited interfacial bonding area between the copper foil and the resin, as the copper foil is a continuous, dense metal foil. Furthermore, interfacial slippage of the copper foil under shear loads slightly reduces interlaminar strength. Three-point bending tests revealed a flexural modulus of 29 GPa and a flexural strength of 380 MPa for the carbon fiber composite.

[0065] The above results show that the carbon fiber composite material prepared in this example shows higher rate performance and coulombic efficiency while maintaining good mechanical properties, which proves the preference and effectiveness of copper foil as a negative electrode material.

[0066] Example 3

[0067] The difference from Example 1 is that the aluminum mesh is replaced by a nickel mesh (the wire diameter of the nickel mesh is 0.1 mm and the pore size is 0.5 mm). The pretreatment method of the nickel mesh is as follows: the nickel mesh is cleaned with acetone to remove oil stains, blown dry and then soaked in 5% dilute hydrochloric acid for 15 minutes, finally rinsed with deionized water and dried; the mixed epoxy resin is composed of bisphenol F type epoxy resin (epoxy equivalent 170e / ep, viscosity 4500mPa·s / 25℃, Shandong Aimont New Materials Co., Ltd., EMTE170) and difunctional glycidylamine type epoxy resin. The resin (epoxy equivalent 125g / ep, viscosity 50mPa·s, Hubei Zhenzhenfeng New Materials Co., Ltd., brand MF-2133) was mixed in a mass ratio of 7:3; the pore-forming agent was PEG-400 and sodium chloride crystals (particle size 10μm), wherein the sodium chloride crystals accounted for 60% of the total mass of the pore-forming agent; the curing agent was a mixed curing agent of m-phenylenediamine and 1,3-cyclohexanedimethylamine in a ratio of 5:5; the ionic liquid was lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-butyl-3-methylimidazolium tetrafluoroborate (PYR 14 TFSI) mixed ionic liquid (LiTFSI and PYR 14 The mass ratio of TFSI is 1:3), and other conditions are the same.

[0068] The electrochemical test was carried out in a two-electrode fixture at room temperature with a test voltage window of 0.5 to 2.4 V. At a current density of 5 mA / g (relative to the mass of the positive electrode activated carbon material), the area specific capacitance and capacity of the carbon fiber composite material remained good, with an energy density of 45 Wh / kg (calculated based on the total mass of the entire carbon fiber composite material). When the discharge rate was increased to 50 mA / g, the carbon fiber composite material was still able to maintain a power density output of approximately 330 W / kg. The cycle life test showed that after 100 cycles, the coulombic efficiency of the carbon fiber composite material stabilized at 93%, and the electrochemical cycle was stable.

[0069] Mechanical properties were tested using the short beam method (per ASTM D2344) to measure interlaminar shear strength, resulting in a value of 22 MPa. This is due to the high strength of the nickel mesh and its good interfacial bonding with the epoxy resin. The pores of the nickel mesh allow the resin to penetrate and cure, forming a mechanically interlocking structure. Three-point bending tests revealed a flexural modulus of 32 GPa and a flexural strength of 390 MPa for the carbon fiber composite.

[0070] The above results show that the carbon fiber composite material prepared with nickel mesh as the negative electrode has excellent mechanical and electrochemical properties.

[0071] Example 4

[0072] The positive electrode was prepared in the same manner as in Example 1.

[0073] Titanium foil (50 μm thick) was used to prepare the negative electrode.

[0074] The stacking order is the same as in Example 1.

[0075] Bisphenol F epoxy resin (Shandong Aimont New Materials Co., Ltd., EMTE170, epoxy equivalent 170g / ep, viscosity 4500mPa·s / 25℃) and alicyclic epoxy resin (Dow Chemical, ERL-4221 epoxy equivalent 131g / eq, viscosity 45mPa·s / 25℃) were mixed in a mass ratio of 1:1, and the obtained mixed epoxy resin and PPG-400 were mixed and stirred in a mass ratio of 1:2 for 40 minutes. After mixing evenly, 4,4'-diaminodicyclohexylmethane HMDA and isophoronediamine IPDA (HMDA and IPDA molar ratio of 1:1) curing agents were added, and the mass ratio of the mixed epoxy resin to the mixed curing agent was 100:33 (i.e., the stoichiometric ratio measured by epoxy equivalent), and continued stirring to obtain a composite resin precursor.

[0076] The mold is sealed and evacuated to a vacuum degree of -0.08MPa. The above-mentioned composite resin precursor is introduced into the mold by vacuum infusion to ensure that the composite resin precursor completely infiltrates all layers. After sealing the mold, it is placed in an oven for curing, first at 110°C for 2h, then heated to 140°C and cured for another 2h to obtain a solid laminate. The epoxy resin bonds the three-layer structure into one. The solid laminate is soaked in deionized water for 24h, taken out and dried in a vacuum oven at 60°C for 24h, and then soaked in an ionic liquid mixed with 1-ethyl-3-methylimidazole bistrifluoromethanesulfonyl imide salt (EMIM-TFSI) and 10wt% aluminum chloride (AlCl3) for 24h to obtain a carbon fiber-titanium integrated energy storage battery.

[0077] The steps of pasting the skin are the same as those in Example 1.

[0078] The electrochemical test was carried out in a two-electrode fixture at room temperature with a test voltage window of 0.5 to 2.4 V. At a current density of 5 mA / g (relative to the mass of the positive electrode activated carbon material), the area specific capacitance and capacity of the carbon fiber composite material remained good, with an energy density of 52 Wh / kg (calculated based on the total mass of the entire carbon fiber composite material). When the discharge rate was increased to 50 mA / g, the carbon fiber composite material was still able to maintain a power density output of approximately 300 W / kg. The cycle life test showed that the coulombic efficiency of the carbon fiber composite material was stable at 94% after 100 cycles, showing good cycle stability.

[0079] Mechanical properties testing used the short beam method (per ASTM D2344) to test interlaminar shear strength, with a result of 28 MPa. Three-point bending tests revealed a flexural modulus of 33 GPa and a flexural strength of 410 MPa for the carbon fiber composite.

[0080] The above results show that the carbon fiber composite material prepared in this example exhibits excellent mechanical properties and reliable electrochemical properties.

[0081] Example 5

[0082] The difference from Example 1 is that the aluminum mesh is replaced by a stainless steel mesh (304 stainless steel mesh, wire diameter of 0.08 mm, pore size of 0.4 mm), and the pretreatment method of the stainless steel mesh is as follows: the stainless steel mesh is cleaned with acetone for 10 min, then pickled for 5 min, rinsed with deionized water and dried; the pore-forming agent is a mixture of PRG-600 and urea (mass ratio of 1:1); the ionic liquid is composed of aluminum chloride (AlCl3) and 1-ethyl-3-methylimidazolium bromide (EMIM-Br), the mass ratio of which is 1.3:1, and the other conditions are the same.

[0083] The electrochemical test was carried out in a two-electrode fixture at room temperature with a test voltage window of 0.5 to 2.4 V. At a current density of 5 mA / g (relative to the mass of the positive electrode activated carbon material), the area specific capacitance and capacity of the carbon fiber composite material remained good, with an energy density of 47 Wh / kg (calculated based on the total mass of the entire carbon fiber composite material). When the discharge rate was increased to 50 mA / g, the carbon fiber composite material was still able to maintain a power density output of approximately 330 W / kg. The cycle life test showed that after 100 cycles, the coulombic efficiency of the carbon fiber composite material stabilized at approximately 92%, and the electrochemical cycle was stable.

[0084] Mechanical properties were tested using the short beam method (performed in accordance with ASTM D2344) to measure interlaminar shear strength, resulting in a value of 25 MPa. This is due to the high toughness of the nickel mesh and its good interfacial bonding with the epoxy resin. The pores of the nickel mesh allow the resin to penetrate and cure, forming a mechanically interlocking structure. Three-point bending tests revealed a flexural modulus of 31 GPa and a flexural strength of 400 MPa for the carbon fiber composite.

[0085] The above results show that the carbon fiber composite material prepared with stainless steel metal mesh as the negative electrode has excellent comprehensive performance.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A structural energy storage integrated carbon fiber composite material, characterized in that: The carbon fiber composite material includes a carbon fiber-metal integrated energy storage battery core and skins on both sides of the carbon fiber-metal integrated energy storage battery core; The carbon fiber-metal integrated energy storage battery core includes a positive electrode, a separator, a negative electrode and a composite porous epoxy resin-based solid electrolyte; the composite porous epoxy resin-based solid electrolyte includes a composite porous epoxy resin and an ionic liquid electrolyte inside the composite porous epoxy resin.

2. The structural energy storage integrated carbon fiber composite material according to claim 1, characterized in that: The positive electrode is carbon-based material modified carbon fiber; the separator is glass fiber fabric; the negative electrode is aluminum mesh, copper foil, nickel mesh, titanium foil or stainless steel metal mesh.

3. The structural energy storage integrated carbon fiber composite material according to claim 1 or 2, characterized in that: The positive electrode, the separator and the negative electrode are composited into an integrated structure with the composite porous epoxy resin as a matrix.

4. The structural energy storage integrated carbon fiber composite material according to claim 3, characterized in that: The carbon-based material modified carbon fiber includes carbon fiber and a carbon-based active material coated on the surface of the carbon fiber.

5. The structural energy storage integrated carbon fiber composite material according to claim 2 or 4, characterized in that: The ionic liquid electrolyte comprises anhydrous aluminum chloride-1-ethyl-3-methylimidazolium chloride, anhydrous aluminum chloride-1-butyl-3-methylimidazolium chloride, anhydrous aluminum chloride-1-ethyl-3-methylimidazolium bromide, anhydrous aluminum chloride-1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide / 1-butyl-3-methylimidazolium tetrafluoroborate.

6. The method for preparing the structural energy storage integrated carbon fiber composite material according to any one of claims 1 to 5, characterized in that: The steps include: S1: pretreating carbon fibers to obtain pretreated carbon fibers, then coating the pretreated carbon fibers with a carbon-based slurry, and drying the pretreated carbon fibers to obtain carbon-based material-modified carbon fibers; S2: pre-treating the negative electrode material to obtain a pre-treated negative electrode; S3: stacking carbon-based material modified carbon fiber, glass fiber fabric, and pretreated negative electrode in sequence, then infusing composite resin precursor by vacuum infusion method, and curing to obtain a solid laminate; S4: soaking and drying the solid laminate, and then impregnating it with an ionic liquid electrolyte to obtain a carbon fiber-metal integrated energy storage battery cell; S5: Pasting skins on both sides of the carbon fiber-metal integrated energy storage battery cell to obtain a carbon fiber composite material.

7. The method for preparing a structural energy storage integrated carbon fiber composite material according to claim 6, characterized in that: In step (1), the carbon-based slurry is made of expanded graphite powder, polyvinylidene fluoride and a solvent.

8. The method for preparing a carbon fiber composite material with integrated structural energy storage according to claim 6 or 7, characterized in that: In step (3), the composite resin precursor is made of a composite epoxy resin, a pore-forming agent and a curing agent; the mass ratio of the composite epoxy resin to the pore-forming agent is 1:1 to 3.

9. The method for preparing a structural energy storage integrated carbon fiber composite material according to claim 8, characterized in that: The composite epoxy resin comprises two or more of bisphenol A epoxy resin, bisphenol F epoxy resin, low-viscosity phenol formaldehyde varnish epoxy resin, difunctional glycidylamine epoxy resin and alicyclic epoxy resin.

10. The method for preparing a structural energy storage integrated carbon fiber composite material according to claim 9, characterized in that: The pore-forming agent comprises one or more of polyethylene glycol, polypropylene glycol, sodium chloride crystals and urea; and the curing agent comprises two or more of 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodiphenylmethane, isophoronediamine, m-xylenediamine and 1,3-cyclohexanedimethylamine.