Composite electrode plate, double-electric-layer supercapacitor and energy storage device

Abstract

The invention discloses a composite electrode plate, a double-electric-layer supercapacitor and an energy storage device, the composite electrode plate is used in the double-electric-layer supercapacitor, and the composite electrode plate comprises a porous composite aluminum foil which comprises a base material layer and a first current collector layer and a second current collector layer which are respectively located on two opposite surfaces of the base material layer; the first active layer is coated on the surface of one side, far away from the base material layer, of the first current collector layer; the second active layer is coated on the surface of one side, far away from the base material layer, of the second current collector layer; the first current collector layer comprises a plurality of first through holes penetrating through the first current collector layer, and the second current collector layer comprises a plurality of second through holes penetrating through the second current collector layer; the base material layer has electron insulativity and ion penetrability. According to the technical scheme provided by the invention, the ion transmission path is increased, the ion transmission distance is shortened, and the charging and discharging rate capability of the double-electric-layer supercapacitor is improved; the porous composite aluminum foil can reduce the product weight by reducing the foil consumption and improve the energy density of the product.

Description

Technical Field

[0001] The present invention relates to the field of supercapacitor technology, and in particular to a composite electrode sheet, a double-layer supercapacitor, and an energy storage device. Background Technology

[0002] Supercapacitors are a new type of energy storage device. They stand out in energy storage technology due to their characteristics such as fast charging, long life and high specific power. They have the characteristics of fast charging and discharging of capacitors as well as the energy storage characteristics of batteries.

[0003] Electric double-layer capacitors (EDLCs) are currently the mainstream application of supercapacitors. Based on the principle of pure electrostatic adsorption, they utilize the porous carbon electrode / electrolyte interface to achieve double-layer energy storage. High specific surface area materials such as activated carbon, carbon fiber, or carbon aerogel are typically used as electrodes to maximize the double-layer capacity on the electrode surface. The charging and discharging process of EDLCs does not involve chemical reactions, thus exhibiting long cycle life and good temperature characteristics. However, with the continuous development of high-power batteries, higher requirements are being placed on the energy density and rate performance of supercapacitors. Summary of the Invention

[0004] This invention provides a composite electrode sheet, an electric double-layer supercapacitor, and an energy storage device to improve the energy density and rate performance of the electric double-layer supercapacitor.

[0005] According to one aspect of the present invention, a composite electrode sheet is provided for use in an electric double-layer supercapacitor, the composite electrode sheet comprising:

[0006] A porous composite aluminum foil comprises a substrate layer and a current collector layer. The current collector layer is divided into a first current collector layer and a second current collector layer, which are located on two opposite surfaces of the substrate layer, respectively.

[0007] A first active layer is coated on the surface of the first current collector layer away from the substrate layer.

[0008] The second active layer is coated on the surface of the second current collector layer away from the substrate layer;

[0009] The first current collector layer includes a plurality of first through holes penetrating the first current collector layer, and the second current collector layer includes a plurality of second through holes penetrating the second current collector layer; the substrate layer has electronic insulation and ion permeability.

[0010] Optionally, at least a portion of the vertical projection of the first through-hole onto the substrate layer overlaps at least partially with the vertical projection of the second through-hole onto the substrate layer.

[0011] Optionally, the first through-hole extends in the thickness direction of the first current collector layer.

[0012] And / or, the second through hole extends in the thickness direction of the second current collector layer.

[0013] Optionally, the first current collector layer and the second current collector layer are made of the same material, namely aluminum.

[0014] And / or, the material of the first active layer includes at least one of activated carbon, carbon nanotubes and graphene, and the material of the second active layer includes at least one of activated carbon, carbon nanotubes and graphene;

[0015] And / or, the material of the substrate layer includes at least one of polyethylene terephthalate, polypropylene, and cellulose.

[0016] Optionally, the vertical projection of the first active layer on the substrate layer overlaps with the vertical projection of the second active layer on the substrate layer; wherein the first active layer and the second active layer are formed synchronously based on the same coating process.

[0017] Optionally, the substrate layer includes a first side and a second side disposed opposite to each other;

[0018] The first current collector layer includes a first extension extending out of the first side at the first side;

[0019] The second current collector layer includes a second extension extending out of the second side at the second side;

[0020] Wherein, the first extension portion is used as the first tab of the composite electrode sheet, and the second extension portion is used as the second tab of the composite electrode sheet.

[0021] Optionally, the material of the first active layer is the same as the material of the second active layer, or is a different type of carbon material; the areal density of the first active layer on the surface of the first current collector layer is the same as or different from the areal density of the second active layer on the surface of the second current collector layer.

[0022] Preferably, the material of the first active layer is the same as the material of the second active layer, but their areal densities are different.

[0023] If the volume of positive ions in the electrolyte is greater than the volume of negative ions, when the first active layer is a positive electrode active layer and the second active layer is a negative electrode active layer, the areal density of the first active layer is less than the areal density of the second active layer; when the first active layer is a negative electrode active layer and the second active layer is a positive electrode active layer, the areal density of the first active layer is greater than the areal density of the second active layer.

[0024] If the volume of positive ions in the electrolyte is smaller than the volume of negative ions, when the first active layer is a positive electrode active layer and the second active layer is a negative electrode active layer, the areal density of the first active layer is greater than the areal density of the second active layer; when the first active layer is a negative electrode active layer and the second active layer is a positive electrode active layer, the areal density of the first active layer is less than the areal density of the second active layer.

[0025] According to another aspect of the present invention, a double-layer supercapacitor is provided, comprising an electrolyte and a composite electrode sheet as described in any embodiment of the present invention, wherein the composite electrode sheet is immersed in the electrolyte.

[0026] Optionally, the double-layer supercapacitor includes at least two composite electrode sheets stacked together; the double-layer supercapacitor further includes a separator disposed between each pair of adjacent composite electrode sheets; the at least two composite electrode sheets and the separator disposed between each pair of adjacent composite electrode sheets form a first stack; in a direction perpendicular to the composite electrode sheets, a first current collector layer and a second current collector layer are alternately disposed in the first stack.

[0027] Alternatively, the double-layer supercapacitor includes at least one composite electrode sheet and at least one separator, wherein the separator and the composite electrode sheet are alternately stacked to form a second stack, and the second stack is spirally wound along the axial direction to form a cylindrical core with a multi-turn structure; wherein the width of the separator is greater than or equal to the width of the composite electrode sheet, and the length of the separator is greater than or equal to the length of the composite electrode sheet, so as to completely isolate adjacent turns of the composite electrode sheet after winding.

[0028] According to another aspect of the present invention, an energy storage device is provided, comprising a housing and a double-layer supercapacitor as described in any embodiment of the present invention, wherein the double-layer supercapacitor is located within the housing.

[0029] The technical solution provided by the embodiments of the present invention, by setting multiple first through holes penetrating the first current collector layer in the first current collector layer and multiple second through holes penetrating the second current collector layer in the second current collector layer, allows ions located in the pores of the first active layer to diffuse to the second active layer through the first through holes, the substrate layer, and the second through holes, and allows ions located in the pores of the second active layer to diffuse to the first active layer through the second through holes, the substrate layer, and the first through holes. This increases the transport path of positive and negative ions in the electrolyte, shortens the ion transport distance, and can effectively improve the charge and discharge rate performance of the double-layer supercapacitor.

[0030] The technical solution provided in this invention uses composite aluminum foil. Under the same thickness, because its substrate is an organic compound, it is lighter than pure aluminum foil, which has a significant effect on reducing the weight of the capacitor and can thus improve the energy density of the double-layer supercapacitor.

[0031] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a cross-sectional schematic diagram of a composite electrode sheet provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram illustrating the working principle of a double-layer supercapacitor provided in an embodiment of the present invention;

[0035] Figure 3 This is a cross-sectional schematic diagram of a stacked double-layer supercapacitor provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the structure of a cylindrical double-layer supercapacitor provided in an embodiment of the present invention;

[0037] Figure 5 yes Figure 4 An enlarged schematic diagram of region Q1 in the structure shown;

[0038] Figure 6 This is a schematic diagram of the structure of a cylindrical double-layer supercapacitor provided in the prior art;

[0039] Figure 7 This is a schematic diagram of the stacking of the first current collector layer, the substrate layer, and the second current collector layer in a composite electrode sheet provided in an embodiment of the present invention;

[0040] Figure 8 This is a schematic diagram of the structure of an energy storage device provided in an embodiment of the present invention. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] This invention provides a composite electrode sheet for use in electric double-layer supercapacitors. Figure 1 This is a cross-sectional schematic diagram of a composite electrode sheet provided in an embodiment of the present invention, for reference. Figure 1 The composite electrode sheet 100 includes:

[0044] The porous composite aluminum foil 10 includes a substrate layer 11, a first current collector layer 12, and a second current collector layer 13; the first current collector layer 12 and the second current collector layer 13 are located on two opposite surfaces of the substrate layer 11.

[0045] The first active layer 20 is coated on the surface of the first current collector layer 12 away from the substrate layer 11;

[0046] The second active layer 30 is coated on the surface of the second current collector layer 13 away from the substrate layer 11;

[0047] The substrate layer 11 has electronic insulation and ion permeability; the first current collector layer 12 includes a plurality of first through holes 121 penetrating the first current collector layer 12; and the second current collector layer 13 includes a plurality of second through holes 131 penetrating the second current collector layer 13.

[0048] Specifically, an electrical double-layer supercapacitor (EDLC) is a capacitor that stores charge using a double-layer structure formed on the electrode surface. When the electrode is immersed in an electrolyte solution and a voltage is applied for charging, the electrode surface adsorbs oppositely polar ions from the electrolyte, forming a dense charge layer. Specifically, the positive electrode surface adsorbs negative ions from the electrolyte, and the negative electrode surface adsorbs positive ions from the electrolyte, forming two charge layers with opposite polarities. Charge storage is accomplished through physical adsorption, rather than a chemical reaction; therefore, the charge-discharge process is highly reversible, and the cycle life is extremely long.

[0049] Figure 2 This is a schematic diagram illustrating the working principle of a double-layer supercapacitor provided in an embodiment of the present invention, as shown below. Figure 2 As shown, a pair of solid electrodes (positive electrode ZJ and negative electrode FJ) are immersed in an electrolyte solution. When a voltage lower than the solution decomposition voltage is applied, charges are distributed and arranged within a very short distance on the solid electrodes. As compensation, the positively charged positive electrode ZJ attracts negative ions from the solution (conversely, the negative electrode FJ attracts positive ions), forming an interface layer with the same number of charges as the remaining charges on the electrode surface but with opposite signs. Due to the potential barrier at the interface, neither layer of charges can cross the boundary to neutralize each other, thus forming a tight electric double layer. Accompanying the formation of the electric double layer, the capacitance formed at the electrode / electrolyte interface is called the electric double layer capacitance, and energy is stored in the form of charge at the interface of the electrode materials. When the electric double layer supercapacitor is charging, electrons are transferred from the positive electrode ZJ to the negative electrode FJ through an external power source, while positive and negative ions in the electrolyte move separately to the adjacent electrode interface; when the electric double layer supercapacitor is discharging, electrons move from the negative electrode FJ to the positive electrode ZJ through a load, while positive and negative ions are released from the electrode interface and move back into the electrolyte.

[0050] The composite electrode sheet 100 provided in this invention is a sandwich structure composed of a porous composite aluminum foil 10, a first active layer 20, and a second active layer 30. Its two sides have electrodes with different polarities: a first electrode composed of the first active layer 20 and a first current collector layer 12 in the porous composite aluminum foil 10, and a second electrode composed of the second active layer 30 and a second current collector layer 13 in the porous composite aluminum foil 10. The first electrode can be a positive electrode (ZJ) and the second electrode a negative electrode (FJ); or the first electrode can be a negative electrode (FJ) and the second electrode a positive electrode (ZJ). A double-layer supercapacitor may include one or more layers of the composite electrode sheet 100. The substrate layer 11 in the porous composite aluminum foil 10 is insulating, used to isolate the first and second electrodes.

[0051] The first active layer 20 and the second active layer 30 are composed of porous materials with high specific surface area (such as activated carbon), containing abundant micropores (<2nm), mesopores (2nm-50nm), and macropores (>50nm). These pore structures significantly expand the physical surface area of ​​the electrodes, providing more adsorption sites for electrolyte ions. The increase in effective surface area depends on whether electrolyte ions can enter the pores. When the pore size matches the ion size (e.g., mesopores can accommodate larger organic electrolyte ions, while micropores are suitable for smaller hydrated ions), an electric double layer can form on the inner surface of the pores, thus contributing to the effective area. Therefore, the microporous structure of the first active layer 20 can significantly increase the effective surface area of ​​the first electrode, and the microporous structure of the second active layer 30 can significantly increase the effective surface area of ​​the second electrode, thereby significantly improving the capacitance of the electric double-layer supercapacitor.

[0052] During the charging process of a double-layer supercapacitor, positive and negative ions in the electrolyte migrate directionally to the corresponding electrode interfaces. If the first electrode is the positive electrode and the second electrode is the negative electrode, the positive ions in the electrolyte migrate directionally to the electrode interface of the second electrode. During the migration, at least some of the positive ions (especially the positive ions in the electrolyte immersed between the second active layers 30) are sequentially adsorbed at the electrode interface of the first active layer 20 through the second through-hole 131 of the second current collector 13, the substrate layer 11 in the porous composite aluminum foil 10, and the first through-hole 121 of the first current collector 12. Similarly, the negative ions in the electrolyte migrate directionally to the electrode interface of the first electrode. During the migration, at least some of the negative ions (especially the negative ions in the electrolyte immersed between the first active materials 20) are sequentially adsorbed at the electrode interface of the second active layer 30 through the first through-hole 121 of the first current collector 12, the substrate layer 11 in the porous composite aluminum foil 10, and the second through-hole 131 of the second current collector 13. If the first electrode is the negative electrode and the second electrode is the positive electrode, then during the charging process, the movement directions of positive and negative ions in the electrolyte are opposite to those when the first electrode is the positive electrode and the second electrode is the negative electrode. This will not be elaborated further here.

[0053] During the discharge process of an electric double-layer supercapacitor, positive and negative ions are released from the electrode interface and migrate back into the electrolyte. The ion migration process is the reverse of the charging process, which will not be elaborated here.

[0054] The technical solution provided by the embodiments of the present invention, by providing a plurality of first through holes 121 penetrating the first current collector layer 12 in the first current collector layer 12 and a plurality of second through holes 131 penetrating the second current collector layer 13 in the second current collector layer 13, allows ions in the pores of the first active layer 20 to diffuse to the second active layer 30 through the first through holes 121, the substrate layer 11 in the porous composite aluminum foil 10 and the second through holes 131 penetrating the second current collector layer 13, and allows ions in the pores of the second active layer 30 to diffuse to the first active layer 20 through the second through holes 131, the substrate layer 11 in the porous composite aluminum foil 10 and the first through holes 121 penetrating the first current collector layer 12, thereby increasing the transport path of positive and negative ions and effectively improving the charge and discharge rate performance of the double-layer supercapacitor.

[0055] Furthermore, the composite electrode sheet 100 provided by this invention is a porous composite foil electrode sheet with electrodes on both sides, which consists of a porous composite aluminum foil 10, a first active layer 20, and a second active layer 30 forming a sandwich structure. The application of porous composite foil electrodes has advantages in improving the energy density of supercapacitors. At the same thickness, because the substrate layer 11 in the porous composite foil electrode sheet is composed of organic compounds, it is lighter than pure metal foil, significantly reducing the weight of the capacitor and thus increasing the energy density of the supercapacitor. For example, composite copper foil electrodes and composite aluminum foil electrodes can reduce weight by 55% and 64% respectively compared to traditional pure metal foil. Replacing traditional aluminum foil with composite aluminum foil can increase the energy density of the supercapacitor system by 5%.

[0056] Optional, Figure 3 This is a cross-sectional schematic diagram of a stacked double-layer supercapacitor provided in an embodiment of the present invention. Figure 4 This is a top view of a cylindrical double-layer supercapacitor provided in an embodiment of the present invention. Figure 5 yes Figure 4 An enlarged schematic diagram of region Q1 in the structure shown, for reference. Figures 3-4 Double-layer supercapacitors can be classified by their shape as stacked double-layer supercapacitors or cylindrical double-layer supercapacitors.

[0057] For a stacked double-layer supercapacitor, the double-layer supercapacitor includes at least two composite electrode sheets 100, which are stacked together. The double-layer supercapacitor also includes a separator 200 disposed between each pair of adjacent composite electrode sheets 100. The at least two composite electrode sheets 100 and the separator 200 disposed between each pair of adjacent composite electrode sheets 100 form a first stack. In a direction perpendicular to the composite electrode sheets 100, a first current collector layer 12 and a second current collector layer 13 are alternately disposed in the first stack. (Reference) Figure 3An exemplary double-layer supercapacitor is shown, comprising three composite electrode sheets: a first composite electrode sheet 101, a second composite electrode sheet 102, and a third composite electrode sheet 103. These three composite electrode sheets 101, 102, and 103 are different composite electrode sheets 100. A second separator 202 is disposed between the first composite electrode sheet 101 and the second composite electrode sheet 102, and a third separator 203 is disposed between the second composite electrode sheet 102 and the third composite electrode sheet 103. The side of the first composite electrode sheet 101 away from the second composite electrode sheet 102 may also include the first separator 201.

[0058] In existing double-layer supercapacitors, each electrode is either a positive or negative electrode. Each electrode consists of a single-layer current collector and an active layer on its surface. Because the current collector is a single metal layer, positive and negative ions in the electrolyte cannot pass through it. Therefore, during the charging and discharging process of the double-layer supercapacitor, ions in the deep voids of the active layer (voids near the current collector in the active layer) within the same electrode can only return to the electrolyte through the active layer. They may even need to pass through the separator 200 to reach adjacent electrodes of opposite polarity. Figure 3 The red arrows indicate transport paths, where ions travel longer distances. In the diagram, a "+" sign indicates a positive electrode, and a "-" sign indicates a negative electrode.

[0059] In the embodiments of the present invention, reference is made to Figure 3 A stacked double-layer supercapacitor formed by at least two porous composite foil electrodes allows ions in the pores of the first active layer 20 to diffuse into the second active layer 30 through the first through-holes 121, the substrate layer 11 in the porous composite aluminum foil 10, and the second through-holes 131 penetrating the second current collector layer 13. Ions in the pores of the second active layer 30 diffuse into the first active layer 20 through the second through-hole 131, the substrate layer 11 in the porous composite aluminum foil 10, and the first through-hole 121 penetrating the first current collector layer 12. This increases the transport path of positive and negative ions in the electrolyte. Since the thickness of the active layer is greater than the thickness of the current collector layer, and the through-hole is a straight through-hole, the increased transport path is much shorter than the original transport path. This can effectively improve the charge and discharge rate performance of the double-layer supercapacitor. Figure 3 In the diagram, the red arrows represent the original ion transport paths, while the green arrows represent the new ion transport paths added based on the first through-hole 121 and the second through-hole 131.

[0060] For cylindrical double-layer supercapacitors, refer to Figure 6 In existing technologies, the electrode sheet typically consists of four layers stacked together: a positive electrode 7, a separator 6, a negative electrode 8, and a separator 6, which are then spirally wound along the axial direction. Furthermore, in existing technologies, the current collector layer in the electrode sheet is a full-surface metal layer. Positive and negative ions in the electrolyte cannot pass through the current collector layer. During the charging and discharging process of the double-layer supercapacitor, ions in the deep voids of the active layer (voids in the active layer near the current collector layer) located in the same ring of electrode sheets can only pass through the active layer back into the electrolyte, and may even need to pass through the separator 6 to move to the vicinity of adjacent opposite electrode sheets.

[0061] In the embodiments of the present invention, reference is made to Figure 4 and Figure 5 The cylindrical double-layer supercapacitor includes at least one composite electrode sheet 100 and at least one separator 200. The separator 200 and the composite electrode sheet 100 are alternately stacked to form a second stack. The second stack is spirally wound along the axial direction to form a cylindrical core with a multi-layer structure. The number of composite electrode sheets 100 and separators 200 is equal. Figure 4 and Figure 5 An exemplary illustration shows a cylindrical double-layer supercapacitor comprising a composite electrode sheet 100 and a separator 200.

[0062] The diaphragm 200 has a width greater than or equal to the width of the composite electrode sheet 100, and the diaphragm 200 has a length greater than or equal to the length of the composite electrode sheet 100, so as to completely isolate the two adjacent turns of the composite electrode sheet 100 after winding. Because the first current collector layer 12 has multiple first through holes 121 penetrating the first current collector layer 12, and the second current collector layer 13 has multiple second through holes 131 penetrating the second current collector layer 13, ions in the pores of the first active layer 20 can diffuse to the second active layer 30 through the first through holes 121, the substrate layer 11 in the porous composite aluminum foil 10, and the second through holes 131 penetrating the second current collector layer 13. Similarly, ions in the pores of the second active layer 30 can diffuse to the first active layer 20 through the second through holes 131, the substrate layer 11 in the porous composite aluminum foil 10, and the first through holes 121 penetrating the first current collector layer 12. This increases the transport path of positive and negative ions in the electrolyte. Furthermore, because the thickness of the active layer is greater than the thickness of the current collector layer, and the through holes are linear, the increased transport path is much shorter than the original transport path. This effectively improves the charge and discharge rate performance of the double-layer supercapacitor. Figure 5 In the diagram, the red arrows represent the original ion transport paths, while the green arrows represent the new ion transport paths added based on the first through-hole 121 and the second through-hole 131.

[0063] Based on the above embodiments, optionally, refer to... Figure 1 , Figure 3 and Figure 5 The vertical projection of at least a portion of the first through-hole 121 onto the substrate layer 11 of the porous composite aluminum foil 10 at least partially overlaps with the vertical projection of the second through-hole 131 onto the substrate layer 11 of the porous composite aluminum foil 10.

[0064] Specifically, for non-overlapping designs, ions must detour through the non-perforated areas of the substrate layer 11 in the porous composite aluminum foil 10, resulting in a circuitous path and increased transport resistance. By setting at least a portion of the vertical projection of the first through-hole 121 onto the substrate layer 11 in the porous composite aluminum foil 10 and the vertical projection of the second through-hole 131 onto the substrate layer 11 in the porous composite aluminum foil 10, ions in the pores of the first active layer 20 can pass through the first through-hole 121, the substrate layer 11 in the porous composite aluminum foil 10, and then through the area of ​​the second through-hole 131 overlapping with the first through-hole 121. Similarly, ions in the pores of the second active layer 30 can pass through the second through-hole 131, the substrate layer 11 in the porous composite aluminum foil 10, and then through the area of ​​the first through-hole 121 overlapping with the second through-hole 131. This shortens the ion migration path, reduces ion migration resistance, and facilitates the rapid charging and discharging of the double-layer supercapacitor.

[0065] Based on the above embodiments, optionally, refer to... Figure 1 , Figure 3 and Figure 5 The first through-hole 121 extends in the thickness direction Z of the first current collector layer 12, and / or the second through-hole 131 extends in the thickness direction Z of the second current collector layer 13. This can further reduce the ion migration path length and significantly reduce ion migration resistance. Preferably, the first through-hole 121 extends in the thickness direction Z of the first current collector layer 12, and the second through-hole 131 extends in the thickness direction Z of the second current collector layer 13, so that ions can penetrate the multilayer structure in a straight line through the overlapping area, further reducing the path length and significantly reducing ion migration resistance.

[0066] Based on the above embodiments, optionally, refer to... Figure 1 , Figure 3 and Figure 5 The first current collector layer 12 and the second current collector layer 13 are used to collect and conduct electric charge. The first current collector layer 12 and the second current collector layer 13 are made of the same material, which can both be aluminum, that is, the first current collector layer 12 and the second current collector layer 13 can both be porous aluminum foil.

[0067] Specifically, commonly used electrolytes for double-layer capacitors include aqueous electrolytes (such as sulfuric acid and potassium hydroxide) and organic electrolytes (such as quaternary ammonium tetrafluoroborate). Aluminum exhibits good chemical stability in neutral or weakly acidic aqueous electrolytes and organic electrolytes, and is not easily oxidized or corroded. The density of aluminum is 2.7 g / cm³. 3 Only copper (8.96 g / cm³) 3 Using aluminum current collectors can significantly reduce the overall weight of devices, making them particularly suitable for weight-sensitive applications such as electric vehicles and portable devices. Furthermore, aluminum is much cheaper than copper, which can significantly reduce the manufacturing cost of double-layer capacitors, especially in large-scale production.

[0068] Based on the above embodiments, optionally, refer to... Figure 1 , Figure 3 and Figure 5 The material of the first active layer 20 includes, but is not limited to, at least one of activated carbon, carbon nanotubes and graphene, and the material of the second active layer 30 includes, but is not limited to, at least one of activated carbon, carbon nanotubes and graphene.

[0069] Specifically, the specific surface area of ​​activated carbon can reach 2500–3000 m². 2 / g, its abundant microporous (<2nm) and mesoporous (2nm~50nm) structure can adsorb a large number of ions in the electrolyte, significantly improving the double-layer capacitance. Activated carbon is low-cost and has a mature process. In addition, activated carbon exhibits good corrosion resistance in acidic, alkaline, and organic electrolytes. The intrinsic conductivity of carbon nanotubes is as high as 10. 3 ~10 4 With a power density of S / cm, it can construct a three-dimensional conductive network, reducing electrode polarization and increasing power density. The predominance of mesopores and macropores (>50nm) in carbon nanotubes facilitates rapid ion diffusion in the electrolyte, supporting second-level charge and discharge. In addition, the self-supporting properties of carbon nanotubes can reduce the amount of binder required and enhance electrode flexibility. The two-dimensional monolayer structure of graphene endows it with ultra-high specific surface area and excellent conductivity. The two-dimensional layered structure can provide high-speed electron conduction paths in the plane, and the interlayer nanochannels promote ion migration, thereby increasing the power density of the device.

[0070] Based on the above embodiments, optionally, refer to... Figure 1 , Figure 3 and Figure 5 The substrate layer 11 in the porous composite aluminum foil 10 is made of at least one of polyethylene terephthalate (PET), polypropylene (PP), and cellulose. The core function of the substrate layer 11 in the porous composite aluminum foil 10 is to prevent direct contact between the first and second electrodes, which could lead to a short circuit, while allowing ions in the electrolyte to pass freely, thereby increasing ion transport pathways.

[0071] Based on the above embodiments, optionally, refer to... Figure 1 , Figure 3 and Figure 5 The vertical projection of the first active layer 20 onto the substrate layer 11 in the porous composite aluminum foil 10 overlaps with the vertical projection of the second active layer 30 onto the substrate layer 11 in the porous composite aluminum foil 10; wherein the first active layer 20 and the second active layer 30 are formed synchronously based on the same coating process.

[0072] Specifically, the composite electrode sheet 100 is coated with a first active layer 20 and a second active layer 30 on both sides, with one of the first active layer 20 and the other active layer 30 being a positive electrode active layer and the other being a negative electrode active layer. Through precise control of the coating technology and simultaneous coating of the positive and negative electrode active layers, it is easy to improve the alignment between the positive and negative electrode active layers, reduce material waste and improve material utilization, while avoiding precision errors caused by processes such as slitting and winding.

[0073] Based on the above embodiments, optionally, refer to... Figure 1 , Figure 3 and Figure 5 and combined Figure 7 The substrate layer 11 of the porous composite aluminum foil 10 includes a first side and a second side disposed opposite to each other; the first current collector layer 12 includes a first extension extending out of the first side at the first side; the second current collector layer 13 includes a second extension extending out of the second side at the second side; wherein the first extension is used as a first tab 122 of the composite electrode sheet 100, and the second extension is used as a second tab 132 of the composite electrode sheet 100.

[0074] It can be understood that, in the embodiments of the present invention, the current collector layers on both sides of the composite electrode sheet 100 are misaligned. In the direction perpendicular to the substrate layer 11 in the porous composite aluminum foil 10, the current collector layers on both sides of the composite electrode sheet 100 have a preset offset relative to the substrate layer 11, and the offset direction of the first current collector layer 12 relative to the substrate layer 11 is opposite to the offset direction of the second current collector layer 13 relative to the substrate layer 11. Figure 7 In the first direction, the offset direction of the second current collector layer 13 relative to the substrate layer 11 is the first direction X, and the offset direction of the first current collector layer 12 relative to the substrate layer 11 is the opposite direction of the first direction X.

[0075] The portion of the first current collector layer 12 offset from the substrate layer 11 is the first extension, and the portion of the second current collector layer 13 offset from the substrate layer 11 is the second extension. By setting the first current collector layer 12 to be laterally offset from the first side of the substrate layer 11, a portion of the first current collector layer 12 can serve as the first tab 121 exposed on the composite electrode sheet 100. Similarly, by setting the second current collector layer 13 to be laterally offset from the second side of the substrate layer 11, a portion of the second current collector layer 13 can serve as the second tab 132 exposed on the composite electrode sheet 100. Furthermore, by positioning the first extension and the second extension on opposite sides of the substrate layer 11 laterally, the distance between the first extension and the second extension can be increased, reducing the probability of a short circuit between the positive and negative electrodes. The exposed first tab 122 and the second tab 132 can be welded to an external tab using ultrasonic or laser welding.

[0076] Based on the above embodiments, optionally, the material of the first active layer 20 and the material of the second active layer 30 may be the same or different; the areal density of the first active layer 20 on the surface of the first current collector layer 12 and the areal density of the second active layer 30 on the surface of the second current collector layer 13 may be the same or different.

[0077] Preferably, the materials of the first active layer 20 and the second active layer 30 are the same but have different areal densities. Specifically, if the volume of positive ions in the electrolyte is greater than the volume of negative ions, when the first active layer 20 is a positive electrode active layer and the second active layer 30 is a negative electrode active layer, the areal density of the first active layer 20 is less than the areal density of the second active layer 30; and when the first active layer 20 is a negative electrode active layer and the second active layer 30 is a positive electrode active layer, the areal density of the first active layer 20 is greater than the areal density of the second active layer 30. Conversely, if the volume of positive ions in the electrolyte is less than the volume of negative ions, when the first active layer 20 is a positive electrode active layer and the second active layer 30 is a negative electrode active layer, the areal density of the first active layer 20 is greater than the areal density of the second active layer 30; and when the first active layer 20 is a negative electrode active layer and the second active layer 30 is a positive electrode active layer, the areal density of the first active layer 20 is less than the areal density of the second active layer 30.

[0078] Specifically, the areal density of the first active layer 20 on the surface of the first current collector layer 12 refers to the mass of the first active layer 20 per unit area of ​​the first current collector layer 12; the areal density of the second active layer 30 on the surface of the second current collector layer 13 refers to the mass of the second active layer 30 per unit area of ​​the second current collector layer 13. During charging, the positive electrode active layer adsorbs anions (such as BF4) from the electrolyte. - PF6 - The negative electrode active layer adsorbs cations (such as EMIM).+ Li + Due to the differences in size, migration rate, and solvation effect of different ions, the charge storage capacity of the positive and negative electrode active layers may be uneven, requiring adjustment of the areal density to match the charge capacity.

[0079] The present invention also provides a double-layer supercapacitor, comprising an electrolyte and a composite electrode sheet 100 as described in any embodiment of the present invention, wherein the composite electrode sheet 100 is immersed in the electrolyte and has the same technical effect.

[0080] Optional, see reference Figure 3 The double-layer supercapacitor includes at least two composite electrode sheets 100, which are stacked together. The double-layer supercapacitor also includes a separator 200 disposed between each two adjacent composite electrode sheets 100. The at least two composite electrode sheets 100 and the separator 200 disposed between each two adjacent composite electrode sheets 100 form a first stack. In the direction perpendicular to the composite electrode sheets 100 (thickness direction Z), a first current collector layer 12 and a second current collector layer 13 are alternately disposed in the first stack.

[0081] Or, refer to Figure 4 and Figure 5 The double-layer supercapacitor includes at least one composite electrode sheet 100 and at least one separator 200. The separator 200 and the composite electrode sheet 100 are alternately stacked to form a second stack. The second stack is spirally wound along the axial direction to form a cylindrical core with a multi-layer structure. Figure 7 The second direction Y is perpendicular to the first direction X and the thickness direction Z. The width of the diaphragm 200 is greater than or equal to the width of the composite electrode sheet 100, and the length of the diaphragm 200 is greater than or equal to the length of the composite electrode sheet 100, so as to completely isolate the two adjacent turns of the composite electrode sheet 100 after winding.

[0082] Specifically, the double-layer supercapacitor can be a stacked double-layer supercapacitor or a cylindrical double-layer supercapacitor in terms of shape. For the stacked double-layer supercapacitor, the double-layer supercapacitor includes at least two composite electrode sheets 100, which are stacked together; the double-layer supercapacitor also includes a separator 200 disposed between each two adjacent composite electrode sheets 100; the at least two composite electrode sheets 100 and the separator 200 disposed between each two adjacent composite electrode sheets 100 form a first stack; in the direction perpendicular to the composite electrode sheets 100, the first current collector layer 12 and the second current collector layer 13 in the first stack are alternately disposed. A stacked double-layer supercapacitor formed by at least two layers of porous composite foil electrodes allows ions in the pores of the first active layer 20 to diffuse into the second active layer 30 through the first through-holes 121, the substrate layer 11 in the porous composite aluminum foil 10, and the second through-holes 131 penetrating the second current collector layer 13. This allows ions in the pores of the second active layer 30 to diffuse into the first active layer 20 through the second through-hole 131, the substrate layer 11 in the porous composite aluminum foil 10, and the first through-hole 121 penetrating the first current collector layer 12. This increases the transport path of positive and negative ions in the electrolyte. Since the thickness of the active layer is greater than the thickness of the current collector layer, and the through-hole is a straight through-hole, the increased transport path is much shorter than the original transport path. This can effectively improve the charge and discharge rate performance of the double-layer supercapacitor.

[0083] For cylindrical double-layer supercapacitors, refer to Figure 6 In existing technologies, a double-layer supercapacitor typically consists of four layers stacked together: a positive electrode 7, a separator 6, a negative electrode 8, and a separator 6, which are then spirally wound along the axial direction. Furthermore, the current collector layer in the electrode sheet is a full-surface metal layer, preventing positive and negative ions in the electrolyte from passing through it. During the charging and discharging process of the double-layer supercapacitor, ions in the deep voids of the active layer (voids near the current collector layer in the active layer) within the same ring of electrode sheets need to pass through the active layer back into the electrolyte, and may even need to pass through the separator 6 to move to the vicinity of adjacent, opposite-polarity electrode sheets.

[0084] In the embodiments of the present invention, reference is made to Figure 4 and Figure 5The cylindrical double-layer supercapacitor includes at least one composite electrode sheet 100 (porous composite foil electrode sheet) and at least one separator 200. The separator 200 and the composite electrode sheet 100 are alternately stacked to form a second stack. The second stack is spirally wound along the axial direction to form a cylindrical core with a multi-turn structure. The width of the separator 200 is greater than or equal to the width of the composite electrode sheet 100, and the length of the separator 200 is greater than or equal to the length of the composite electrode sheet 100, so as to completely isolate the two adjacent turns of the composite electrode sheet 100 after winding. Because the first current collector layer 12 has multiple first through holes 121 penetrating the first current collector layer 12, and the second current collector layer 13 has multiple second through holes 131 penetrating the second current collector layer 13, ions in the pores of the first active layer 20 can diffuse to the second active layer 30 through the first through holes 121, the substrate layer 11 in the porous composite aluminum foil 10, and the second through holes 131 penetrating the second current collector layer 13. Similarly, ions in the pores of the second active layer 30 can diffuse to the first active layer 20 through the second through holes 131, the substrate layer 11 in the porous composite aluminum foil 10, and the first through holes 121 penetrating the first current collector layer 12. This increases the transport path of positive and negative ions in the electrolyte. Furthermore, because the thickness of the active layer is greater than the thickness of the current collector layer, and the through holes are linear, the increased transport path is much shorter than the original transport path. This effectively improves the charge and discharge rate performance of the double-layer supercapacitor. Furthermore, compared to the existing technology which uses two electrode layers and two separator layers, the technical solution provided by this invention requires only one electrode layer and one separator layer, greatly reducing the difficulty of winding, significantly increasing the winding rate, and saving costs in terms of equipment precision control. In addition, by placing the positive and negative electrodes on opposite surfaces of the same substrate layer 11 in the porous composite aluminum foil 10, the alignment of the positive and negative electrodes is controlled during the coating stage. During the winding process, there is no need to consider the alignment of the positive and negative electrodes; as long as the separator 200 covers the active material layer, the winding difficulty is greatly reduced.

[0085] This invention also provides an energy storage device, including a housing and a double-layer supercapacitor as described in any embodiment of the invention, wherein the double-layer supercapacitor is located within the housing.

[0086] Optional, see reference Figure 8 The double-layer supercapacitor is a cylindrical double-layer supercapacitor, which includes a composite electrode sheet 100 (porous composite foil electrode sheet) and a separator 200. The separator 200 and the composite electrode sheet 100 are alternately stacked to form a second stack. The second stack is spirally wound along the axial direction to form a cylindrical core with a multi-layer structure. The cylindrical core is placed in a cylindrical shell to form a cylindrical battery 1.

[0087] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A composite electrode sheet, characterized in that, For use in electric double-layer supercapacitors, the composite electrode sheet includes: A porous composite aluminum foil comprises a substrate layer and a current collector layer. The current collector layer is divided into a first current collector layer and a second current collector layer, which are located on two opposite surfaces of the substrate layer, respectively. A first active layer is coated on the surface of the first current collector layer away from the substrate layer. The second active layer is coated on the surface of the second current collector layer away from the substrate layer; The first current collector layer includes a plurality of first through holes penetrating the first current collector layer, and the second current collector layer includes a plurality of second through holes penetrating the second current collector layer; the substrate layer has electronic insulation and ion permeability.

2. The composite electrode sheet according to claim 1, characterized in that, At least a portion of the vertical projection of the first through-hole onto the substrate layer overlaps at least partially with the vertical projection of the second through-hole onto the substrate layer.

3. The composite electrode sheet according to claim 1, characterized in that, The first through hole extends in the thickness direction of the first current collector layer. And / or, the second through hole extends in the thickness direction of the second current collector layer.

4. The composite electrode sheet according to claim 1, characterized in that, The first current collector layer and the second current collector layer are made of the same material, aluminum. And / or, the material of the first active layer includes at least one of activated carbon, carbon nanotubes and graphene, and the material of the second active layer includes at least one of activated carbon, carbon nanotubes and graphene; And / or, the material of the substrate layer includes at least one of polyethylene terephthalate, polypropylene, and cellulose.

5. The composite electrode sheet according to claim 1, characterized in that, The vertical projection of the first active layer onto the substrate layer overlaps with the vertical projection of the second active layer onto the substrate layer; wherein the first active layer and the second active layer are formed synchronously based on the same coating process.

6. The composite electrode sheet according to claim 1, characterized in that, The substrate layer includes a first side and a second side disposed opposite to each other; The first current collector layer includes a first extension extending out of the first side at the first side; The second current collector layer includes a second extension extending out of the second side at the second side; Wherein, the first extension portion is used as the first tab of the composite electrode sheet, and the second extension portion is used as the second tab of the composite electrode sheet.

7. The composite electrode sheet according to claim 1, characterized in that, The material of the first active layer is the same as the material of the second active layer, or it is a different type of carbon material; the areal density of the first active layer on the surface of the first current collector layer is the same as or different from the areal density of the second active layer on the surface of the second current collector layer. Preferably, the material of the first active layer is the same as the material of the second active layer, but their areal densities are different. If the volume of positive ions in the electrolyte is greater than the volume of negative ions, when the first active layer is a positive electrode active layer and the second active layer is a negative electrode active layer, the areal density of the first active layer is less than the areal density of the second active layer; when the first active layer is a negative electrode active layer and the second active layer is a positive electrode active layer, the areal density of the first active layer is greater than the areal density of the second active layer. If the volume of positive ions in the electrolyte is smaller than the volume of negative ions, when the first active layer is a positive electrode active layer and the second active layer is a negative electrode active layer, the areal density of the first active layer is greater than the areal density of the second active layer; when the first active layer is a negative electrode active layer and the second active layer is a positive electrode active layer, the areal density of the first active layer is less than the areal density of the second active layer.

8. A double-layer supercapacitor, characterized in that, It includes an electrolyte and a composite electrode sheet according to any one of claims 1 to 7, wherein the composite electrode sheet is immersed in the electrolyte.

9. The double-layer supercapacitor according to claim 8, characterized in that, The double-layer supercapacitor includes at least two composite electrode sheets stacked together; the double-layer supercapacitor also includes a separator disposed between each pair of adjacent composite electrode sheets; the at least two composite electrode sheets and the separator disposed between each pair of adjacent composite electrode sheets form a first stack; in a direction perpendicular to the composite electrode sheets, a first current collector layer and a second current collector layer are alternately disposed in the first stack. Alternatively, the double-layer supercapacitor includes at least one composite electrode sheet and at least one separator, wherein the separator and the composite electrode sheet are alternately stacked to form a second stack, and the second stack is spirally wound along the axial direction to form a cylindrical core with a multi-turn structure; wherein the width of the separator is greater than or equal to the width of the composite electrode sheet, and the length of the separator is greater than or equal to the length of the composite electrode sheet, so as to completely isolate adjacent turns of the composite electrode sheet after winding.

10. An energy storage device, characterized in that, It includes a housing and a double-layer supercapacitor as described in claim 8 or claim 9, wherein the double-layer supercapacitor is located within the housing.

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