A supercapacitor and a method of manufacturing the same

Abstract

The application provides a super capacitor and a preparation method thereof. The super capacitor provided by the application is integrally and complexly processed by a fiber reinforced resin matrix composite material and a hole double-layer capacitor, specifically, the double-layer capacitor with a hole structure is laid between fiber cloths or prepregs, the holes on the hole double-layer capacitor are filled with resin in a molding process, a "rivet" structure is formed and connected with an external fiber reinforced structure layer, on the basis of ensuring good electricity storage performance, the in-plane shear resistance, out-of-plane tensile property and impact resistance of the structural super capacitor are effectively improved, and the super capacitor also has excellent waterproof performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite materials, in particular to a supercapacitor and a preparation method thereof. BACKGROUND

[0002] With the global greenhouse effect intensifying, it is particularly urgent to reduce or even eliminate the use of fossil fuels that cause greenhouse gas emissions. For example, the European Union has set a target of net zero greenhouse gas emissions by 2050. New energy vehicles represented by electric vehicles comply with the development trend of green environmental protection, and have broad market prospects. Of course, the electrification of automobiles also puts higher requirements on energy storage systems. New energy storage systems not only should have higher energy density and power density to meet people's pickiness on mileage and horsepower, but also should be as small as possible in mass and volume to meet the development needs of automobile lightweight and energy saving and emission reduction, and to minimize the space occupied by the energy storage system. In recent years, new multifunctional structural energy storage composites have emerged as the times require. The material takes fiber reinforced composites as the carrier, stores electrical energy, and at the same time can serve as a structural member to resist load, and plays an important role in effectively reducing the mass of the system and improving the efficiency of the system.

[0003] The electrical storage element mainly includes batteries, capacitors and supercapacitors. In recent years, researchers in various countries have made more explorations in structural batteries and structural capacitors, while the research on structural supercapacitors is relatively less. Supercapacitors have the advantages of high power density and long cycle service life, and their power density is higher than that of batteries, and their energy density is higher than that of general capacitors. As an indispensable multifunctional energy storage system, structural supercapacitors will inevitably have broad application prospects in the field of new energy electric vehicles.

[0004] So far, the methods implemented by scholars to realize structural batteries or structural capacitors mainly fall into two categories. One approach is to develop a new type of structural electrolyte, synthesize a new type of solid-state electrolyte polymer that has both ion transport ability and certain load-bearing capacity. However, the ion transport ability and structural performance of the polymer electrolyte are inherently contradictory because its ionic conductivity will decrease with the decrease of the mobility of the polymer chain. Therefore, it is still difficult to realize a structural supercapacitor with load-bearing capacity in the true sense, and once the load-bearing capacity is increased, the electrical storage performance is difficult to meet the requirements.

[0005] Another approach is to embed or intercalate energy storage elements into fiber reinforced composites to form a composite element that has both load bearing and energy storage functions. This approach is simple and has been used in commercial production. However, the embedded energy storage elements mostly exist as foreign objects in the composite material, which can easily induce delamination damage. For example, an examination of multiple commercial brands of lithium ion pouch cells found no evidence of physical or chemical bonding between the active cell and the pouch packaging. This means that the cell and the outer packaging cannot effectively transfer load through frictional shear and normal tensile tension. Therefore, in the design of such a structure of the battery, the battery will be limited to the position of the favorable deformation mode (such as out-of-plane compression or in-plane tension), which greatly limits the freedom of structural design. For planar supercapacitors (double layer capacitors, EDLC), there is also a similar risk of delamination damage. This is mainly because, on the one hand, the separator in the EDLC layer is very soft, and its resistance to opening / sliding between adjacent layers is minimal. On the other hand, aluminum foil is usually used as the current collector, which is usually poorly bonded to the polymer composite layer and can also be a potential source of delamination damage. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a supercapacitor and a preparation method thereof. The supercapacitor prepared by the present application can improve the in-plane shear resistance and out-of-plane tensile resistance of the material and the impact resistance, and ensure the use stability and service life of the material.

[0007] The present application provides a preparation method of a supercapacitor, comprising the following steps:

[0008] A) placing a porous double layer capacitor in the middle layer position of a fiber woven fabric preform to obtain a fiber preform;

[0009] B) pouring a resin mixture into the fiber preform, and then curing to obtain a supercapacitor;

[0010] wherein,

[0011] The porous double layer capacitor comprises, in order:

[0012] a bottom film;

[0013] a first carbon nanotube fiber yarn layer;

[0014] a polymer electrolyte film;

[0015] a second carbon nanotube fiber yarn layer;

[0016] a top film;

[0017] The first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer are both provided with holes, and the through holes are formed from the first carbon nanotube fiber yarn layer to the second carbon nanotube fiber yarn layer, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are both greater than the hole size of the polymer electrolyte thin film.

[0018] Or

[0019] The holey double electric layer capacitor comprises, in sequence, the following layers in contact:

[0020] The first carbon nanotube fiber yarn layer;

[0021] The polymer electrolyte thin film;

[0022] The second carbon nanotube fiber yarn layer;

[0023] The first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer are both provided with holes, and the through holes are formed from the first carbon nanotube fiber yarn layer to the second carbon nanotube fiber yarn layer, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are both greater than the hole size of the polymer electrolyte thin film.

[0024] Preferably, the polymer electrolyte thin film is formed of a high polymer and an ionic liquid;

[0025] The high polymer is selected from one or more of polyvinylidene fluoride-hexafluoropropylene, a copolymer of polyvinylidene fluoride-hexafluoropropylene and polymethyl methacrylate;

[0026] The ionic liquid is selected from one or more of n-methyl-n-butyl pyrrole bis trifluoromethyl sulfonic acid imide and n-methyl-n-propyl pyrrole bis trifluoromethyl sulfonic acid imide.

[0027] Preferably, the mass ratio of the high polymer to the ionic liquid is 1:(1-2).

[0028] Preferably, the bottom film is a polymer thin film, and the polymer is PVA; and the surface film is a polymer thin film, and the polymer is PVA.

[0029] Preferably, the fiber fabric preform is a composite of a plurality of layers of fiber fabric stacked together.

[0030] The fiber fabric is a continuous carbon fiber fabric, a continuous basalt fiber fabric, a continuous glass fiber fabric or a continuous aramid fiber fabric.

[0031] Preferably, the fiber fabric is a unidirectional fiber fabric or a multidirectional fiber fabric.

[0032] Preferably, the resin mixture solution comprises a resin and a curing agent.

[0033] Preferably, the resin is a thermosetting resin, including one or more of epoxy resin, polyester resin, phenolic resin, vinyl ester resin and bismaleimide resin;

[0034] The curing agent is selected from one or more of methyl ethyl ketone peroxide and dicyandiamide.

[0035] Preferably, in step B), the infusion is by vacuum assisted resin transfer molding process, resin transfer molding process, hand lay-up molding or autoclave molding.

[0036] The application also provides a supercapacitor prepared by the preparation method.

[0037] The supercapacitor prepared by the application has a novel structure of "rivet" interlocking mechanism, and is integrally processed by a fiber reinforced resin matrix composite material and a hole double-layer capacitor. Specifically, the double-layer capacitor with a hole structure is laid between the fiber cloth or prepreg. The hole on the hole double-layer capacitor is filled with resin during the molding process, forming a "rivet" structure connected with the external fiber reinforced structure layer. On the basis of ensuring good power storage performance, the in-plane shear resistance and out-of-plane tensile performance and impact resistance of the structural supercapacitor are effectively improved, and the structural and functional integration is truly realized.

[0038] The test results show that the supercapacitor prepared by the application has high energy density and power density, and excellent electrical performance; at the same time, it also has high out-of-plane tensile performance (bending strength and bending modulus) and in-plane shear resistance, and excellent mechanical performance; in addition, it also has excellent waterproof performance. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0040] Figure 1 A schematic diagram of the composite obtained in steps S1-S6;

[0041] Figure 2 A schematic diagram of the supercapacitor prepared by the application;

[0042] Figure 3 A schematic diagram of the single shear specimen in Example 3;

[0043] Figure 4Figure for the test result of in-plane shear strength in the performance test of Example 3;

[0044] Figure 5 Figure for the shear failure surface of the capacitor with no resin "rivet" structure of Comparative Example 1;

[0045] Figure 6 Figure for the shear failure surface of the supercapacitor with resin "rivet" structure of Example 2;

[0046] Figure 7 Figure for the comparison of the constant current charge and discharge test results of the porous double-layer capacitor before and after immersion;

[0047] Figure 8 Figure for the comparison of the constant current charge and discharge test results of the supercapacitor before and after immersion. DETAILED DESCRIPTION

[0048] The present application provides a preparation method of a supercapacitor, comprising the following steps:

[0049] A) inserting the porous double-layer capacitor into the position between the middle layers of the fiber woven fabric preform to obtain a fiber preform;

[0050] B) pouring the resin mixture into the fiber preform, and then curing to obtain a supercapacitor;

[0051] wherein,

[0052] The porous double-layer capacitor comprises, in contact and stacked in sequence:

[0053] a bottom film;

[0054] a first carbon nanotube fiber yarn layer;

[0055] a polymer electrolyte film;

[0056] a second carbon nanotube fiber yarn layer;

[0057] a surface film;

[0058] wherein each layer is provided with holes, and a through hole is formed between the surface film and the bottom film, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are larger than the hole size of the polymer electrolyte film;

[0059] or

[0060] The porous double-layer capacitor comprises, in contact and stacked in sequence:

[0061] a first carbon nanotube fiber yarn layer;

[0062] a polymer electrolyte film;

[0063] a second carbon nanotube fiber yarn layer;

[0064] wherein each layer is provided with a hole, and a through hole is formed from the first carbon nanotube fiber yarn layer to the second carbon nanotube fiber yarn layer, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are greater than the hole size of the polymer electrolyte thin film.

[0065] The supercapacitor prepared by the application has a novel structure of a rivet interlocking mechanism, and is integrally processed by a fiber reinforced resin matrix composite material and a hole double-layer capacitor. Specifically, the hole double-layer capacitor with a hole structure is laid between fiber cloths or pre-pregs. The hole on the hole double-layer capacitor is filled with resin in the molding process to form a rivet structure connected with the external fiber reinforced structure layer. On the basis of ensuring good power storage performance, the in-plane shear resistance, out-of-plane tensile performance and impact resistance of the structural supercapacitor are effectively improved, and the structural and functional integration is truly realized.

[0066] [About the hole double-layer capacitor]:

[0067] In the application, the structure of the hole double-layer capacitor is divided into two types, as described above.

[0068] About the first hole double-layer capacitor:

[0069] The first hole double-layer capacitor includes the following layers which are sequentially laminated and combined:

[0070] a bottom film;

[0071] a first carbon nanotube fiber yarn layer;

[0072] a polymer electrolyte thin film;

[0073] a second carbon nanotube fiber yarn layer;

[0074] a top film;

[0075] wherein each layer is provided with a hole, and a through hole is formed from the top film to the bottom film, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are greater than the hole size of the polymer electrolyte thin film.

[0076] In the application, the polymer electrolyte thin film is located in the middle layer of the hole double-layer capacitor.

[0077] The polymer electrolyte film is preferably formed by a high molecular polymer and an ionic liquid. The high molecular polymer is preferably one or more of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and a copolymer of polyvinylidene fluoride-hexafluoropropylene and polymethyl methacrylate (PVDF-HFP / PMMA). The ionic liquid is preferably one or more of n-methyl-n-butyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) and n-methyl-n-propyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR13TFSI). In the present application, the mass ratio of the high molecular polymer to the ionic liquid is preferably 1:(1-2). If the mass ratio is too high, the ionic conductivity of the electrolyte cannot meet the requirements, and if the mass ratio is too low, the mechanical properties of the electrolyte will obviously degrade. Within the above ratio range, good electrical and mechanical properties can be ensured. The mass ratio can be 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2.0.

[0078] In the present application, the first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer are respectively arranged on the upper and lower sides of the polymer electrolyte film.

[0079] The thickness of the first carbon nanotube fiber yarn layer is preferably 5-20 μm, and can be 5 μm, 10 μm, 15 μm, or 20 μm. The density of the carbon nanotube fiber yarn layer before opening of the first carbon nanotube fiber yarn layer is preferably 0.5-2 g / m 2 .

[0080] The thickness of the second carbon nanotube fiber yarn layer is preferably 5-20 μm, and can be 5 μm, 10 μm, 15 μm, or 20 μm. The density of the carbon nanotube fiber yarn layer before opening of the second carbon nanotube fiber yarn layer is preferably 0.5-2 g / m 2 .

[0081] In the present application, more preferably, the density and thickness of the first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer are the same. In the present application, the preparation method of the carbon nanotube fiber yarn is not particularly limited, and can be prepared according to the conventional preparation method in the art, and can be prepared by floating catalytic chemical vapor deposition (FCCVD), the process is as follows: carbon source is cracked in a high temperature reaction furnace, and carbon nanotubes are grown on the surface of the catalyst, a large number of carbon nanotubes are aggregated and entangled with each other to form carbon nanotube aerogel, the carbon nanotube aerogel can be continuously pulled out from the other end of the high temperature reaction furnace and deposited on the surface of the substrate to form a fluffy yarn structure, i.e. carbon nanotube fiber yarn.

[0082] In the present application, the bottom layer film and the surface layer film are respectively located outside the first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer.

[0083] In the present application, the bottom layer film is a polymer film, and the polymer is preferably PVA (polyvinyl alcohol). In the present application, the thickness of the bottom layer film is preferably 5-20 μm, and can be 5 μm, 10 μm, 15 μm or 20 μm.

[0084] In the present application, the surface layer film is a polymer film, and the polymer is preferably PVA (polyvinyl alcohol). In the present application, the thickness of the bottom layer film is preferably 5-20 μm, and can be 5 μm, 10 μm, 15 μm or 20 μm.

[0085] In the present application, the bottom layer film and the surface layer film are not particularly limited in orientation, and both are the outermost layer of the double electric layer capacitor. If one of them is the bottom layer film, the other one is naturally the surface layer film. In the present application, more preferably, the types and thicknesses of the bottom layer film and the surface layer film are the same. In the present application, the bottom layer film and the surface layer film have an insulating packaging function.

[0086] In the present application, each layer is provided with a hole, and a through hole is formed from the surface film to the bottom film, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are greater than the hole size of the polymer electrolyte film. The present application controls the formation of a through hole from top to bottom of the hole double electric layer capacitor as a whole, preferably, the position of each hole of each layer corresponds to the position of each hole of the adjacent layer, and the center point of each hole of each layer coincides with the center point of the corresponding hole of the adjacent layer. The present application also controls the hole size of the two carbon nanotube fiber yarn layers to be greater than the hole size of the intermediate polymer electrolyte film, so as to prevent the short circuit caused by the direct contact between the two carbon nanotube fiber yarn layers. In the present application, more preferably, the hole sizes of the bottom film, the surface film and the intermediate polymer electrolyte film are consistent, the hole sizes of the two carbon nanotube fiber yarn layers are consistent, and the hole sizes of the two carbon nanotube fiber yarn layers are greater than the hole sizes of the other three film layers; the hole sizes of the two carbon nanotube fiber yarn layers are slightly greater than the hole sizes of the other layers, so that the two carbon nanotube fiber yarn layers cannot be directly contacted. In the present application, the hole shape includes but is not limited to circular, elliptical, square or polygonal, etc.

[0087] In the present application, the total thickness of the hole double electric layer capacitor is preferably 10-300 μm.

[0088] Regarding the second hole double electric layer capacitor:

[0089] The second hole double electric layer capacitor comprises the following layers which are stacked in sequence:

[0090] The first carbon nanotube fiber yarn layer;

[0091] The polymer electrolyte film;

[0092] The second carbon nanotube fiber yarn layer;

[0093] In the present application, each layer is provided with a hole, and a through hole is formed from the first carbon nanotube fiber yarn layer to the second carbon nanotube fiber yarn layer, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are greater than the hole size of the polymer electrolyte film.

[0094] Compared with the structure of the first hole double electric layer capacitor, the second hole double electric layer capacitor only omits the bottom film and the surface film, and the types, thicknesses and other characteristics of the first carbon nanotube fiber yarn layer, the polymer electrolyte film and the second carbon nanotube fiber yarn layer are consistent with those described in the first hole double electric layer capacitor, which will not be repeated here.

[0095] In the present application, the first hole double electric layer capacitor is prepared by the following preparation method:

[0096] S1, laying a bottom film precursor without holes;

[0097] S2, laying a first carbon nanotube fiber yarn layer with pre-holes on the surface of the bottom film precursor;

[0098] S3, laying a polymer electrolyte film precursor without holes on the surface of the first carbon nanotube fiber yarn layer;

[0099] S4, laying a second carbon nanotube fiber yarn layer with pre-holes on the surface of the polymer electrolyte film;

[0100] wherein each hole of the second carbon nanotube fiber yarn layer is aligned with each hole of the first carbon nanotube fiber yarn layer;

[0101] S5, laying a surface film precursor without holes on the surface of the second carbon nanotube fiber yarn layer to obtain a composite precursor;

[0102] S6, compression molding the composite precursor to obtain a composite;

[0103] S7, according to the hole positions of the first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer, making through holes in the corresponding positions of the composite, and making the size of the through holes smaller than the hole size of the first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer.

[0104] Referring to Figure 1 , Figure 1 FIG. 1 is a schematic diagram of the composite obtained by steps S1-S6, i.e., the composite structure before the through holes are made in step S7, wherein 1 is the bottom film precursor, 2 is the first carbon nanotube fiber yarn layer, 3 is the polymer electrolyte film precursor, 4 is the second carbon nanotube fiber yarn layer, and 5 is the surface film precursor.

[0105] Regarding step S1:

[0106] In the present application, the bottom film precursor is preferably prepared by the following method: S1a, dissolving a polymer in a solvent to obtain a coating liquid; and S1b, volatilizing the solvent after coating the coating liquid to obtain the bottom film precursor.

[0107] wherein:

[0108] The polymer is preferably PVA (i.e., polyvinyl alcohol).

[0109] The solvent is preferably a mixed solvent of an organic solvent and water. The organic solvent is preferably ethanol. The volume ratio of the organic solvent: water is preferably 1:(1-2), and can be 1:1 or 1:2. The amount ratio of the polymer: solvent is preferably 1 g:(5-10) mL.

[0110] The temperature for dissolving is preferably 90-95°C, and can be 90°C, 91°C, 92°C, 93°C, 94°C or 95°C. The preferred implementation is as follows: the solvent is heated to the above temperature in advance, and then the polymer particles are added to the solvent for dissolving.

[0111] The coating method is not particularly limited, and can be performed according to the conventional film coating method in the art, for example, spreading the coating liquid by using a film coater. After coating, the solvent is fully volatilized to obtain the un-pored bottom layer precursor film.

[0112] Regarding step S2:

[0113] The un-pored carbon nanotube fiber yarn layer is obtained in the same manner as described above, and will not be repeated here. After obtaining the un-pored carbon nanotube fiber yarn layer, the carbon nanotube fiber yarn layer is perforated by using a perforating device to obtain a perforated first carbon nanotube fiber yarn layer. The first carbon nanotube fiber yarn layer is placed on the surface of the bottom layer precursor obtained in step S1.

[0114] Regarding step S3:

[0115] In the present application, the polymer electrolyte film precursor is preferably prepared by the following method: S3a, dissolving the high molecular polymer and the ionic liquid in a solvent to obtain a coating liquid; S3b, after coating the coating liquid, volatilizing the solvent to obtain the polymer electrolyte film precursor.

[0116] In the present application, the polymer electrolyte film precursor is preferably prepared by the following method: S3a, dissolving the high molecular polymer and the ionic liquid in a solvent to obtain a coating liquid; S3b, after coating the coating liquid, volatilizing the solvent to obtain the polymer electrolyte film precursor.

[0117] The types and amounts of the high molecular polymer and the ionic liquid are the same as described in the technical solutions above, and will not be repeated here.

[0118] The solvent is preferably acetone. The amount ratio of the high molecular polymer to the solvent is preferably 1g:(6-8)mL.

[0119] The temperature for dissolving is not particularly limited, and can be performed at room temperature.

[0120] The coating method is not particularly limited, and can be performed according to the conventional film coating method in the art, for example, spreading the coating liquid by using a film coater. After coating, the solvent is fully volatilized to obtain the un-pored bottom layer precursor film.

[0121] Regarding step S4:

[0122] The un-pored carbon nanotube fiber yarn layer is obtained in the same manner as described above, and will not be repeated here. After obtaining the un-pored carbon nanotube fiber yarn layer, the carbon nanotube fiber yarn layer is perforated by using a perforating device to obtain a perforated first carbon nanotube fiber yarn layer. The first carbon nanotube fiber yarn layer is placed on the surface of the bottom layer precursor obtained in step S1.

[0123] Regarding step S5:

[0124] The preparation method of the surface layer film precursor is consistent with the preparation method of the bottom layer film precursor in step S1, which is not repeated here. After obtaining the un-pored surface layer film precursor, it is placed on the surface of the second carbon nanotube fiber yarn layer obtained in step S4. Through the above steps S1-S5, a composite with layers stacked is obtained.

[0125] Regarding step S6:

[0126] The pressure of the press forming is preferably 1-5 MPa, and can be specifically 1.0 MPa, 1.5 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa, 4.5 MPa, or 5.0 MPa. The time of the press is preferably 10-20 min, and can be specifically 10 min, 15 min, or 20 min. After the press forming, a composite is obtained.

[0127] Regarding step S7:

[0128] When the through hole is opened, a hole opening device can be used for operation. The size, shape, and other requirements of the hole opening are consistent with those described in the technical solutions above, which are not repeated here. After the above treatment, a hole double-layer capacitor is obtained.

[0129] In the present application, the preparation process of the second hole double-layer capacitor is basically the same as that of the first hole double-layer capacitor described above, except that the steps of laying the bottom layer film and the surface layer film are omitted, which are not repeated here.

[0130] [Regarding step A]:

[0131] A) : Place the hole double-layer capacitor between the middle layers of the fiber woven fabric preform to obtain a fiber preform.

[0132] In the present application, the types and preparation methods of the hole double-layer capacitor are as described above, which are not repeated here.

[0133] In the present application, the fiber woven fabric preform is a composite with several layers of fiber woven fabrics stacked. The fiber woven fabric is a unidirectional fiber woven fabric or a multidirectional fiber woven fabric. The number of layers of fiber woven fabrics in the fiber woven fabric preform is not particularly limited and can be designed according to actual needs. In some embodiments of the present application, it is 8 layers.

[0134] In the present application, the fiber fabric is preferably a continuous carbon fiber fabric, a continuous basalt fiber fabric, a continuous glass fiber fabric, or a continuous aramid fiber fabric. When using conductive fibers (such as carbon fibers) as the reinforcing phase of the structural layer, the double-layer capacitor needs to be insulated and packaged, i.e., the first type of double-layer capacitor with holes described above is used; when using other non-conductive fibers, no insulation packaging is required, i.e., the second type of double-layer capacitor with holes described above is used.

[0135] In the present application, the placement of the double-layer capacitor with holes in the middle position of the fiber fabric preform is not particularly limited, such as inserting the double-layer capacitor with holes into the middle position of the fiber fabric preform; or first laying a half number of layers of fiber fabric as a base, laying the double-layer capacitor with holes on the surface, and then covering the other half number of layers of fiber fabric, so that the double-layer capacitor with holes is in the middle position. In the present application, the size of the double-layer capacitor with holes can be consistent with the size of the fiber fabric preform, i.e., the two are completely overlapped when stacked; or it can be designed to be partially covered as needed. Through the above processing, a fiber preform is obtained.

[0136] [About step B]:

[0137] B) : pouring the resin mixture into the fiber preform, and then curing to obtain a supercapacitor.

[0138] In the present application, the resin mixture includes resin and curing agent. The resin is a thermosetting resin, including but not limited to one or more of epoxy resin, polyester resin, phenolic resin, vinyl resin, and bismaleimide resin. In some embodiments of the present application, the resin used is bisphenol A epoxy resin Derakane 8084. In the present application, the curing agent is preferably one or more of methyl ethyl ketone peroxide (MEKP) and dicyandiamide. The amount of curing agent is preferably 1wt% to 1.5wt% of the amount of resin.

[0139] In the present application, the pouring forming method of pouring the resin mixture into the fiber preform obtained in step A) can be vacuum assisted resin transfer molding (VARTM), resin transfer molding (RTM), hand lay-up molding, or autoclave molding, and is more preferably vacuum assisted resin transfer molding (VARTM). The mass ratio of the resin mixture to the fiber preform obtained in step A) is preferably (0.5-1) : 1, and can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1.0:1.

[0140] In the present application, after the above infusion molding, a composite structure embryo is obtained, and then curing is performed. In the present application, the temperature of the curing is preferably 25-80 DEG C. The time of the curing is preferably 4-24 h. After the curing, a structural super capacitor with fibers as a reinforcing phase is formed.

[0141] The present application also provides a super capacitor prepared by the preparation method.

[0142] The super capacitor prepared by the present application has a novel structure of a "rivet" interlocking mechanism, and is integrally processed by a fiber reinforced resin matrix composite material and a hole double-layer capacitor. Specifically, the hole double-layer capacitor with a hole structure is laid between fiber cloth or a prepreg. The hole on the hole double-layer capacitor is filled with resin during the molding process, and a "rivet" structure is formed to be connected with an external fiber reinforced structure layer. On the basis of ensuring good power storage performance, the in-plane shear resistance and out-of-plane tensile performance and impact resistance of the structural super capacitor are effectively improved, and the structural and functional integration is truly realized.

[0143] Referring to Figure 2 , Figure 2 FIG. 1 is a schematic diagram of the super capacitor prepared by the present application, wherein 1 is a resin "rivet", 2 is a hole double-layer capacitor, 3 is a surface film in the hole double-layer capacitor, 4 is a resin layer (which is interconnected with the "rivet"), and 5 is a fiber reinforced composite material.

[0144] The structural super capacitor prepared by the present application is a power storage element. Compared with traditional structural batteries and capacitors, the in-plane and out-of-plane mechanical properties of the structural super capacitor are further strengthened, and the degree of freedom of the structural design is greatly improved. The implementer can select different fiber materials according to different application requirements, and can adjust the number of the implanted hole double-layer capacitors and the size of the holes to adjust the in-plane shear strength and the power storage capacity. In addition, due to the use of the integrated molding process, the packaging effect is better, and the waterproof performance is good.

[0145] The super capacitor prepared by the present application has the following beneficial effects:

[0146] 1. The novel structural super capacitor provided by the present application not only has a large power density, but also has excellent mechanical properties, and truly realizes structural-functional integration.

[0147] 2. Compared with the traditional embedding method, the integrated molding design of the resin "rivet" effectively improves the in-plane shear resistance and out-of-plane tensile performance of the energy storage element.

[0148] 3、The hole double electric layer capacitor used in the application can be designed into an ultrathin structure, can greatly reduce the thickness and mass of the whole composite material plate, and has strong designability.

[0149] 4、The application adopts an integrated forming process, has good sealing performance, and has excellent waterproof effect.

[0150] 5、The carbon nanotube fiber yarn is used as the electrode and current collector, is combined with other film layers and fiber materials, has high specific capacitance, and has good mechanical properties and fatigue resistance.

[0151] The test results show that the supercapacitor prepared by the application has high energy density and power density, excellent electrical performance, high out-of-plane tensile performance (bending strength and bending modulus), and excellent in-plane shear resistance and mechanical performance.

[0152] In order to further understand the application, the preferred embodiments of the application are described below in combination with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the application, and are not limitations on the claims of the application.

[0153] Example 1: Preparation of hole double electric layer capacitor

[0154] 1、Preparation of materials:

[0155] K1, dissolve the high molecular polymer PVDF-HFP and the ionic liquid PYR14TFSI in the acetone solvent according to the mass ratio of 1:1.5 (the amount ratio of high molecular polymer: solvent = 3g: 20mL), then uniformly spread the mixed solution by means of a film applicator, and obtain a polymer electrolyte thin film precursor film layer with a thickness of about 60μm after the acetone is volatilized.

[0156] K2, dissolve the PVA particles in the ethanol-water mixed solvent at 90℃ (the volume ratio of ethanol: water = 1:1, the amount ratio of PVA particles: mixed solvent = 1g: 5mL), spread by means of a film applicator, and obtain a PVA film with a thickness of about 15μm after the ethanol and water are volatilized.

[0157] K3, prepare the carbon nanotube fiber yarn by means of floating catalytic chemical vapor deposition (FCCVD), and the surface density is about 1.6g / m 2 , the size of the carbon nanotube fiber yarn is: 48mm in length x 24mm in width. Then, round holes are punched on the carbon nanotube fiber yarn, the radius R of the round hole is 3mm, and a total of 4 holes are punched.

[0158] 2、Preparation:

[0159] S1, take one PVA film as the bottom layer film precursor film layer.

[0160] S2, take a layer of open hole carbon nanotube fiber yarn laid on the bottom layer of film precursor film layer, recorded as the first carbon nanotube fiber yarn layer.

[0161] S3, take a layer of polymer electrolyte film precursor film laid on the first carbon nanotube fiber yarn layer.

[0162] S4, take another layer of open hole carbon nanotube fiber yarn laid on the polymer electrolyte film precursor film, recorded as the second carbon nanotube fiber yarn layer.

[0163] S5, take another layer of PVA film laid on the second carbon nanotube fiber yarn layer as the surface layer of film precursor film layer, get the composite precursor. Structure as Figure 1 shown.

[0164] S6, the composite precursor is formed under the pressure of 2.5 MPa for 10 min, and the composite is obtained.

[0165] S7, according to the hole position of the first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer, the through hole is opened in the corresponding position of the composite, and the size of the through hole is smaller than the hole size of the first carbon nanotube fiber yarn layer and the second carbon nanotube fiber yarn layer, so as to obtain the hole double layer capacitor.

[0166] After detection, the thickness of the obtained hole double layer capacitor is about 100 μm, the energy density is 1.12 Wh / kg, and the power density is 656 W / kg.

[0167] Example 2: preparation of new structure super capacitor

[0168] A), cut 8 layers of carbon fiber cloth (Hexcel G0926), the cutting size is: length 210 cm x width 25 cm, lay the fiber cloth preform in [0°]8 stacking mode, and insert the hole double layer capacitor obtained in example 1 into the middle layer position of the fiber cloth preform, to obtain the fiber preform.

[0169] B), mix 100 g of low viscosity bisphenol A epoxy resin (Derakane 8084) with 1.5 g of curing agent methyl ethyl ketone peroxide to obtain a resin mixture. The resin mixture is poured into the fiber preform obtained in step A) by vacuum assisted resin transfer molding (VARTM) technology. Then, cure at room temperature for 48 h, demold and edge cutting, to obtain a super capacitor with resin "rivet" structure with carbon fiber as reinforcing phase. Structure as Figure 2 shown.

[0170] After detection, the bending strength of the obtained super capacitor is 153 MPa, and the bending modulus is 60 GPa. The energy density of the obtained super capacitor is 0.037 Wh / kg, and the power density is 30 W / kg.

[0171] Comparative Example 1: Preparation of a capacitor with a resin-free "rivet" structure

[0172] 1. Fabrication of a hole-free electric double-layer capacitor

[0173] The implementation follows Example 1, except that the carbon nanotube fiber yarn does not have holes and the step of creating through holes in step S7 is not performed.

[0174] 2. Fabrication of supercapacitors

[0175] According to Example 2, the difference is that the perforated double-layer capacitor is replaced with the above-mentioned non-perforated double-layer capacitor, resulting in a capacitor with a resin-free "rivet" structure.

[0176] Example 3: Product Testing

[0177] 1. In-plane shear strength test

[0178] The supercapacitor obtained in Example 1 and the capacitor obtained in Comparative Example 1 were prepared according to... Figure 3 A single-shear specimen was prepared, with a length of 200 mm and a width of 24 mm after cutting. The electric double-layer capacitor (EDLC) layer of the cut specimen in Comparative Example 1 did not have any through-holes (such as...). Figure 3 The EDLC layer of the cut sample in Example 2 (shown in the lower left) has through-holes (as shown in the lower left sample). Figure 3 (The sample shown in the lower right corner).

[0179] Shear test results as follows Figure 4 As shown, Figure 4 The figure shows the test results of in-plane shear strength in Example 3. It can be seen that the capacitor in Comparative Example 1, without the resin "rivet" structure, can hardly withstand any in-plane shear load; while the capacitor in Example 2, with the resin "rivet" structure, has significantly improved shear resistance, withstanding shear loads up to 2250N. The main reason for this is that the components of the double-layer capacitor do not bond well together, easily leading to delamination. The resin "rivet" effect effectively transfers the load, improving its shear resistance.

[0180] A schematic diagram of the shear failure surface after shear testing is shown below. Figures 5-6 As shown, where, Figure 5 This is a schematic diagram of the shear failure surface of the capacitor with the resin-free "rivet" structure in Comparative Example 1. Figure 6 This is a schematic diagram of the shear failure surface of the supercapacitor with resin "rivet" structure in Example 2, where 7 is the polymer electrolyte membrane and 1 is the resin "rivet" hole.

[0181] 2. Waterproofing test

[0182] The hole double electric layer capacitor obtained in Example 1 and the super capacitor obtained in Example 2 were respectively immersed in water for 12 hours, and the changes in electrochemical performance were compared and analyzed by constant current charge and discharge test. Figures 7-8 Figure 7 Figure 4 is a comparison chart of constant current charge and discharge test results of the hole double electric layer capacitor of Example 1 before and after water immersion. Figure 8 Figure 5 is a comparison chart of constant current charge and discharge test results of the super capacitor of Example 2 before and after water immersion.

[0183] It can be seen that the electrochemical performance of the hole double electric layer capacitor of Example 1 is obviously degraded after immersion. The electrochemical performance of the super capacitor of Example 2 does not change significantly after immersion. It is proved that the super capacitor provided by the present application has excellent waterproof performance.

[0184] The principles and implementation modes of the present application are described by applying specific examples in this paper. The above examples are only used to help understand the method of the present application and its core idea, including the best mode, and also enable any person skilled in the art to practice the present application, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for ordinary skilled persons in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application. The scope of patent protection of the present application is defined by the claims, and can include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.​

Claims

1. A method for preparing a supercapacitor, characterized in that, The method comprises the following steps: A) placing a porous electric double layer capacitor in the middle layer position of a fiber fabric preform to obtain a fiber preform; B) pouring a resin mixture into the fiber preform, and then curing to obtain a super capacitor; wherein, the porous electric double layer capacitor comprises, in order, a bottom film, a first carbon nanotube fiber yarn layer, a polymer electrolyte film, a second carbon nanotube fiber yarn layer, and a surface film; wherein each layer is provided with holes, and a through hole is formed from the surface film to the bottom film, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are larger than the hole size of the polymer electrolyte film; or the porous electric double layer capacitor comprises, in order, a first carbon nanotube fiber yarn layer, a polymer electrolyte film, and a second carbon nanotube fiber yarn layer; wherein each layer is provided with holes, and a through hole is formed from the first carbon nanotube fiber yarn layer to the second carbon nanotube fiber yarn layer, and the hole size of the first carbon nanotube fiber yarn layer and the hole size of the second carbon nanotube fiber yarn layer are larger than the hole size of the polymer electrolyte film; the polymer electrolyte film is formed of a high molecular polymer and an ionic liquid; the high molecular polymer is selected from one or more of polyvinylidene fluoride-hexafluoropropylene, a copolymer of polyvinylidene fluoride-hexafluoropropylene and polymethyl methacrylate; the ionic liquid is selected from one or more of n-methyl-n-butyl pyrrole bis-trifluoromethyl sulfonic acid imide and n-methyl-n-propyl pyrrole bis-trifluoromethyl sulfonic acid imide. The mass ratio of the high molecular polymer to the ionic liquid is 1:(1-2). The bottom film is a polymer film, and the polymer is PVA. The surface film is a polymer film, and the polymer is PVA. The fiber fabric preform is a composite of a plurality of layers of fiber fabric stacked together; The fiber fabric is continuous carbon fiber fabric, continuous basalt fiber fabric, continuous glass fiber fabric, or continuous aramid fiber fabric. The fiber fabric is unidirectional fiber fabric or multidirectional fiber fabric. The resin mixture comprises a resin and a curing agent. The resin is a thermosetting resin, and is selected from one or more of epoxy resin, polyester resin, phenolic resin, vinyl resin, and bismaleimide resin; 2. The production method according to claim 1, characterized by, The curing agent is selected from one or more of methyl ethyl ketone peroxide and dicyandiamide.

3. The production method according to claim 1, characterized by, In step B), the pouring method is vacuum assisted resin transfer molding process, resin transfer molding process, hand lay-up molding, or autoclave molding.

9. A super capacitor prepared by the preparation method of any one of claims 1-8.

4. The production method according to claim 1, characterized by, ​ ​ 5. The production method according to claim 4, characterized by, ​ 6. The method of claim 1, wherein, ​ 7. The preparation method according to claim 6, characterized in that, ​ ​ 8. The method of claim 1, wherein, ​ ​

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