Internal parallel supercapacitor and manufacturing method thereof

Abstract

The invention discloses an internal parallel type super capacitor and a manufacturing method thereof, the internal parallel type super capacitor comprises a battery cell wrapped with an insulating layer, the top and the bottom of the battery cell are respectively provided with a negative current collector and a positive current collector, the battery cell is arranged in an aluminum shell with a top opening, and the top of the aluminum shell is provided with a negative aluminum cover; the battery cell is formed by sequentially stacking a negative electrode plate containing a negative electrode lug, a diaphragm and a positive electrode plate containing a positive electrode lug, central holes are formed in the middle parts of the negative electrode plate and the positive electrode plate, the negative electrode lug is connected to a negative current collector after being stacked and shaped, the negative current collector is connected with a negative aluminum cover, and the negative aluminum cover is connected with a positive electrode of the battery cell. After being stacked, the positive electrode tabs are shaped and connected to the positive electrode current collecting piece, the positive electrode current collecting piece is connected with the aluminum shell, and organic electrolyte is infiltrated in the battery cell. The problems that in the prior art, electrolyte infiltration is difficult, infiltration uniformity is poor, and capacitance is low can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage, and in particular relates to an internal parallel supercapacitor and a manufacturing method thereof. Background Art

[0002] Supercapacitors, also known as electrochemical capacitors, store energy by forming a stable double layer of electrolyte ions on the electrode surface or by adsorption and desorption in the two- or three-dimensional space of the electrode. They are a new type of energy storage device between conventional capacitors and secondary batteries. Supercapacitors offer advantages such as high specific capacitance, high power density, environmental friendliness, rapid charge and discharge, and long cycle life. They combine the high power output of traditional capacitors with the charge storage capacity of secondary batteries. Currently, supercapacitors are finding increasingly widespread application in new energy, power storage, rail transportation, aerospace, and other fields.

[0003] Common packaging forms for supercapacitors include cylindrical aluminum shells and soft-pack aluminum-plastic films, while the traditional wound supercapacitor assembly is mainly achieved by winding the pole pieces and diaphragms together. However, as the height of the core and the roll diameter ratio increase, electrolyte infiltration becomes more difficult and the infiltration uniformity deteriorates, leading to increased internal resistance of the supercapacitor, uneven heat generation, deterioration of various performances, and lower capacitance. In traditional wound double-layer supercapacitors, the electrodes inside the core are connected in series. The electrostatic capacitance of the supercapacitor is one-fourth of the electrostatic capacitance of the total active material, and the overall capacitance is not easy to increase. Another type of supercapacitor in the form of laminated sheets is achieved by alternating stacking of pole pieces and diaphragms. It has high capacitance, and the external packaging is mainly achieved by thermal sealing of aluminum-plastic film, which carries a high risk of electrolyte leakage. The Chinese patent application with publication number CN209388893 alternately stacks cylindrical electrodes and diaphragms and places them in a cylindrical aluminum shell to eventually form an internal series capacitor. Its main purpose is to improve the low voltage of aqueous supercapacitors and solve the problem that individual electrode sheets decompose the electrolyte due to excessively high carrying voltage caused by inconsistent electrodes. After stacking, the voltage can be increased to above 5V, but the problem of low capacitance cannot be solved. Summary of the Invention

[0004] The object of the present invention is to provide an internal parallel supercapacitor and a method for manufacturing the same, so as to solve the problems of electrolyte wetting difficulty, poor wetting uniformity and low capacitance in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: An internal parallel supercapacitor comprises a cell wrapped with an insulating layer on the outside, a negative electrode current collector sheet and a positive electrode current collector sheet provided on the top and bottom of the cell, respectively. The cell is placed in an aluminum shell with an open top, and a negative electrode aluminum cover is provided on the top of the aluminum shell; The battery cell is formed by stacking a negative electrode sheet including a negative electrode tab, a separator, and a positive electrode sheet including a positive electrode tab in sequence. A central hole is provided in the middle of the negative electrode sheet and the positive electrode sheet. After the negative electrode tabs are stacked, they are shaped and connected to the negative electrode current collecting sheet, and the negative electrode current collecting sheet is connected to the negative electrode aluminum cover. After the positive electrode tabs are stacked, they are shaped and connected to the positive electrode current collecting sheet, and the positive electrode current collecting sheet is connected to the aluminum shell. The battery cell is soaked with an organic electrolyte.

[0006] Furthermore, the positive electrode sheet includes a current collector and a positive electrode active material layer adhered to the upper and lower surfaces of the current collector, and the exposed portion of the current collector to which the positive electrode active material layer is not adhered is the positive electrode tab; The negative electrode sheet includes a current collector and negative electrode active material layers adhered to the upper and lower surfaces of the current collector. The exposed portion of the current collector to which the negative electrode active material layer is not adhered is the negative electrode tab.

[0007] Furthermore, the raw materials for preparing the positive electrode active material layer include a positive electrode active material, a conductive agent, a binder and a thickener, and the mass ratio of the positive electrode active material, the conductive agent, the binder and the thickener is (85-98): (1-8): (1-5): (0-2); The raw materials for preparing the negative electrode active material layer include a negative electrode active material, a conductive agent, a binder and a thickener, and the mass ratio of the negative electrode active material, the conductive agent, the binder and the thickener is (85~97): (1~8): (1~5): (1~2).

[0008] Furthermore, the positive electrode active material adopts one or both of activated carbon and lithium-based positive electrode materials; The lithium-based positive electrode material is lithium iron phosphate, lithium nickel cobalt oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide or lithium manganese oxide.

[0009] Furthermore, the negative electrode active material is one or both of activated carbon and pre-lithiation negative electrode material; The pre-lithiation negative electrode material is graphite, silicon carbon or silicon oxide.

[0010] Furthermore, the binder is one or a combination of two of polyacrylic acid, styrene-butadiene rubber and polytetrafluoroethylene; The thickener is sodium carboxymethyl cellulose; The conductive agent is one or more of carbon black, acetylene black, carbon nanotubes, and graphene; The current collector is one or both of aluminum foil and copper foil.

[0011] Furthermore, the edge of the negative electrode active material layer is 0-2 mm larger than the edge of the positive electrode active material layer, and the edge of the separator is 1-4 mm larger than the edge of the negative electrode active material layer.

[0012] Furthermore, the diameter of the central hole in the middle of the negative electrode sheet and the positive electrode sheet is 0.1 mm to 8 mm.

[0013] Furthermore, the diaphragm is one of a cellulose diaphragm, a non-woven fabric diaphragm, a polypropylene diaphragm, a polytetrafluoroethylene-based diaphragm and a ceramic diaphragm.

[0014] A method for manufacturing an internal parallel supercapacitor, comprising: preparing strip-shaped coated positive electrode sheets and strip-shaped coated negative electrode sheets for processing positive electrode sheets and negative electrode sheets respectively; Based on the strip-shaped coated positive electrode sheet and the strip-shaped coated negative electrode sheet, the positive electrode sheet and the negative electrode sheet are obtained by cutting; stacking the negative electrode sheet, the separator and the positive electrode sheet in sequence; After stacking the negative electrode tabs of the negative electrode sheets, they are shaped and connected to the negative electrode current collector. After stacking the positive electrode tabs of the positive electrode sheets, they are shaped and connected to the positive electrode current collector to form a battery cell. The positive electrode current collector of the battery cell is connected to the aluminum shell, and the negative electrode current collector is connected to the negative electrode aluminum cover. The interior of the battery cell is evenly infiltrated with organic electrolyte and sealed in the area surrounded by the aluminum shell and the negative electrode aluminum cover to complete the production of the internal parallel supercapacitor.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: In the present invention, the positive electrode sheet and the negative electrode sheet are connected in parallel to form the positive terminal and the negative terminal respectively, which can effectively reduce the contact resistance. The stacked electrode sheets (including the positive electrode sheet and the negative electrode sheet) containing the central hole provide more channels for the electrolyte infiltration, and the infiltration efficiency and uniformity are better. The consistency of the battery cell is greatly improved. At the same time, the size of the supercapacitor with this structure can be flexibly adjusted and is easier to implement in terms of process.

[0016] When preparing supercapacitors, the present invention radially increases the size of the electrode sheets based on the stacking method, which does not affect the penetration efficiency of the electrolyte. Therefore, compared with wound capacitors, the electrostatic capacitance of the internal parallel supercapacitor is easier to increase; the center hole in the internal parallel structure can be used for positioning during the stacking process to improve the concentricity of the electrode stack. At the same time, the set center hole and parallel structure can also serve as longitudinal and radial penetration channels for the electrolyte during the injection process, thereby improving the electrolyte penetration efficiency and uniformity, thereby improving the consistency of internal resistance and capacity.

[0017] In addition, by combining the advantages of cylindrical cells and laminated cells, the design flexibility of supercapacitors in height and radial direction can be achieved, and the mass production of ultra-large capacity supercapacitor cells can be achieved more easily. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] Figure 1 Schematic diagram of the overall structure of the internal parallel cylindrical supercapacitor.

[0020] Figure 2 Schematic diagram of a circular negative electrode sheet.

[0021] Figure 3 A schematic side view of a circular negative electrode sheet.

[0022] Figure 4 Schematic diagram of the diaphragm.

[0023] Figure 5 Schematic diagram of a circular positive electrode sheet.

[0024] Figure 6 A schematic side view of a circular positive electrode sheet.

[0025] Figure 7 Schematic diagram of the stacking structure of a circular negative electrode sheet, a circular positive electrode sheet and a diaphragm.

[0026] Figure 8 This is the front view of the positive electrode current collector.

[0027] Figure 9 This is a side view of the positive electrode current collector.

[0028] Figure 10 This is the front view of the negative electrode current collector.

[0029] Figure 11 This is a side view of the negative electrode current collector.

[0030] Among them, 1-negative electrode sheet; 101-negative active material layer; 102-negative electrode tab; 2-diaphragm; 3-positive electrode sheet; 301-positive active material layer; 302-positive electrode tab; 4-battery cell; 5-negative current collector; 6-positive current collector; 601-positive electrode column; 7-negative aluminum cover; 701-negative electrode column; 8-aluminum shell; 9-insulating tape; 11-insulating ring. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is introduced in detail below.

[0032] In order to combine the advantages of low internal resistance and high capacity of cylindrical and soft-pack supercapacitors, the present invention proposes an internal parallel supercapacitor and a manufacturing method thereof. The internal parallel supercapacitor proposed in the present invention aims to utilize the parallel relationship between the negative electrode sheet 1 and the positive electrode sheet 3 inside the supercapacitor to improve the capacity of the supercapacitor. At the same time, the central hole in the stacked structure (i.e., the battery cell) and the stacked contact gap between the negative electrode sheet 1, the positive electrode sheet 3, and the diaphragm 2 can improve the infiltration efficiency of the electrolyte in the battery cell 4, further improve the consistency between the performance of the supercapacitor monomers, and effectively improve the overall performance of the supercapacitor.

[0033] First, the present invention provides an internal parallel supercapacitor, such as Figures 1 to 7 As shown, the battery cell 4 is composed of a positive electrode sheet 3 containing a positive electrode tab 302, a negative electrode sheet 1 containing a negative electrode tab 102, and a separator 2. There is a separator 2 between the adjacent positive electrode sheets 3 and the negative electrode sheets 1. The positive electrode sheet 3 includes a positive electrode tab 302 and a center hole, and the negative electrode sheet 1 includes a negative electrode tab 102 and a center hole. The positive electrode tab 302 and the negative electrode tab 102 are stacked separately and shaped separately. The positive current collecting sheet 6 and the negative current collecting sheet 5 are connected to form a battery cell 4 with the positive current collecting sheet 6 and the negative current collecting sheet 5. The positive current collecting sheet 6 of the battery cell 4 is connected to the aluminum shell 8, and the negative current collecting sheet 5 is connected to the negative aluminum cover 7. The interior of the battery cell 4 is evenly infiltrated with an organic electrolyte and is sealed inside a column surrounded by the aluminum shell 8 and the negative aluminum cover 7. The raised portion of the positive current collecting sheet 6 serves as the positive electrode column 601, and the raised portion of the negative aluminum cover 7 serves as the negative electrode column 701 at the negative end.

[0034] In the above-mentioned internally parallel high-capacity supercapacitor, the positive electrode sheet 3 and the negative electrode sheet 1 are punched or laser cut into a circular structure with a central hole (including a positive electrode tab 302 and a negative electrode tab 102). The positive electrode sheet 3 includes a current collector and a positive electrode active material layer 301 adhered to the upper and lower surfaces of the current collector. The exposed portion of the current collector to which the positive electrode active material layer 301 is not adhered is the positive electrode tab 302. The negative electrode sheet 1 includes a current collector and a negative electrode active material layer 101 adhered to the upper and lower surfaces of the current collector. The exposed portion of the current collector to which the negative electrode active material layer 101 is not adhered is the negative electrode tab 102. The positive electrode active material layer 301 on the upper and lower surfaces of the positive electrode sheet 3 is composed of a positive electrode active material, a conductive agent, a binder, and a thickener in a mass ratio of (85-98): (1-8): (1-5): (0-2), wherein the positive electrode active material is one or a combination of two of activated carbon, lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium manganese oxide; The negative electrode active material layer 101 on the upper and lower surfaces of the negative electrode sheet 1 is composed of a negative electrode active material, a conductive agent, a binder, and a thickener in a mass ratio of (85-97): (1-8): (1-5): (1-2), wherein the negative electrode active material is one or a combination of two of activated carbon, graphite, silicon carbon, and silicon oxide; In the positive electrode active material layer 301 and the negative electrode active material layer 101 on the upper and lower surfaces of the positive electrode sheet 3 and the negative electrode sheet 1, the binder is one of polyacrylic acid PAA, styrene-butadiene rubber SBR and polytetrafluoroethylene PVDF; In the positive electrode active material layer 301 and the negative electrode active material layer 101 on the upper and lower surfaces of the positive electrode sheet 3 and the negative electrode sheet 1, the thickener is sodium carboxymethyl cellulose CMC; In the positive electrode active material layer 301 and the negative electrode active material layer 101 on the upper and lower surfaces of the positive electrode sheet 3 and the negative electrode sheet 1, the conductive agent is one or more of carbon black, acetylene black, carbon nanotubes, and graphene; The positive electrode active material layer 301 and the negative electrode active material layer 101 are mixed with a solvent to form a positive electrode slurry and a negative electrode slurry, respectively. The positive electrode slurry and the negative electrode slurry are applied to the upper and lower surfaces of the current collector to form a strip-shaped coated positive electrode sheet and a strip-shaped coated negative electrode sheet, respectively. The solvent is deionized water or N-methylpyrrolidone (NMP). The strip-shaped coated positive electrode sheet and the strip-shaped coated negative electrode sheet are punched or laser cut into positive electrode sheets 3 and negative electrode sheets 1 with central holes, with the blank portion on one side being the tabs (corresponding to the positive tab 302 on the positive electrode sheet 3 and the negative tab 102 on the negative electrode sheet 1). Specifically, the central holes of the positive electrode sheet 3 and the negative electrode sheet 1 are circular holes with a diameter of 0.1 mm to 8 mm, preferably 2 mm. Preferably, the positive electrode sheet 3 and the negative electrode sheet 1 are circular in shape; the diameter of the circular positive electrode sheet 3 and the negative electrode sheet 1 is 45-150 mm; The diaphragm 2 is one of a cellulose diaphragm, a non-woven fabric diaphragm, a polypropylene diaphragm, a polytetrafluoroethylene diaphragm and a ceramic diaphragm; The current collectors used for the positive electrode sheet 3 and the negative electrode sheet 1 can both be aluminum foil, or the current collector used for the positive electrode sheet 3 can be aluminum foil and the current collector used for the negative electrode sheet 1 can be copper foil; In the battery cell 4 formed by alternating stacking of the positive electrode sheets 3, the separator 2, and the negative electrode sheets 1, the edge of the negative active material layer 101 on the negative electrode sheet 1 is 0-2 mm larger than the edge of the positive active material layer 301 on the positive electrode sheet 3, and the edge of the separator 2 is 1-4 mm larger than the edge of the negative active material layer 101 on the negative electrode sheet 1; In the above-mentioned battery cell 4, the positive electrode tabs 302 and the negative electrode tabs 102 are stacked on both sides, and after being shaped, they are respectively connected to the positive electrode current collector 6 and the negative electrode current collector 5 by laser welding; preferably, the positive electrode current collector 6 is an aluminum material current collector with a circular structure, and the structure is as follows: Figure 8 and Figure 9 As shown, it is connected to the aluminum shell 8 by laser welding; preferably, the negative electrode current collector 5 is a current collector with a circular structure of aluminum material, which is connected to the negative electrode aluminum cover 7 by laser welding and sealed by an insulating ring, as shown Figure 10 and Figure 11 shown.

[0035] Secondly, the present invention provides a method for manufacturing an internal parallel supercapacitor. In the first step, the positive electrode active material, the conductive agent, the binder and the thickener are mixed with the solvent according to the ingredient ratio to form a positive electrode slurry. Similarly, the negative electrode active material, the conductive agent, the binder and the thickener are mixed with the solvent according to the ingredient ratio to form a negative electrode slurry. After coating and rolling, strip-shaped coated positive electrode sheets and strip-shaped coated negative electrode sheets are formed; in the second step, the strip-shaped coated positive electrode sheets and the strip-shaped coated negative electrode sheets are punched or laser cut into positive electrode sheets 3 and negative electrode sheets 1 with center holes, and the positive electrode sheets are 3. The diaphragm 2 and the negative electrode sheet 1 are alternately stacked into a columnar battery cell 4, and the positive electrode tabs 302 and the negative electrode tabs 102 on both sides of the battery cell 4 are shaped; in the third step, the shaped positive electrode tabs 302 and the negative electrode tabs 102 are respectively connected to the positive current collecting sheet 6 and the negative current collecting sheet 5, wherein the positive current collecting sheet 6 is connected to the aluminum shell 8, and the negative current collecting sheet 5 is connected to the negative aluminum cover 7; in the fourth step, the surface of the battery cell 4 is wrapped with insulating tape 9, and an insulating ring 11 is placed on the negative end. After being placed in the aluminum shell 8, it is grooved and sealed; in the fifth step, after the sealed battery cell 4 is baked, liquid is injected, and then the injection hole is sealed. After activation, an internal parallel supercapacitor is obtained.

[0036] The positive electrode sheet 3 and the negative electrode sheet 1 in the present invention are preferably cut into a circular shape by laser or die cutting. Figure 2 and Figure 3 )、Diaphragm 2( Figure 4 ) and the positive electrode sheet 3 ( Figure 5 and Figure 6 ) are alternately stacked to form a columnar laminated battery cell 4 ( Figure 7 ); Battery cell 4 and negative electrode current collector 5 ( Figure 10 and Figure 11 ) and positive electrode current collector 6 ( Figure 8 and Figure 9 ) are connected, the positive electrode current collecting sheet 6 is connected to the shell 8 to form the positive electrode of the supercapacitor, and the negative electrode current collecting sheet 5 is connected to the negative electrode aluminum cover 7 to form the negative electrode of the supercapacitor.

[0037] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0038] Example 1 The present invention provides a method for manufacturing an internal parallel cylindrical supercapacitor. In the first step, 89 parts by mass of activated carbon, 5.5 parts of conductive agent carbon black, 2 parts of thickener CMC, 3.5 parts of binder styrene-butadiene rubber (SBR) and deionized water are mixed to form an electrode slurry (including positive electrode slurry and negative electrode slurry), which is then applied to the upper and lower surfaces of aluminum foil to form an upper and lower surface density of 0.6 g / dm 2 Strip coated electrode sheets (including strip coated positive electrode sheets and strip coated negative electrode sheets); second, the strip coated electrode sheets are rolled to a thickness of 220um, and are cut into circular positive electrode sheets 3 and negative electrode sheets 1 with a diameter of 45mm, a center hole diameter of 0.1mm, and a tab arch height of 3mm. The positive electrode sheet 3, the separator 2, the negative electrode sheet 1 and the cellulose separator with a diameter of 48mm are arranged in a Figure 7 The stacking method is to alternately stack the battery cells 4 into a columnar shape, and shape the positive electrode tabs 302 and the negative electrode tabs 102 on both sides of the battery cell 4; in the third step, the shaped positive electrode tabs 302 and the negative electrode tabs 102 are respectively connected to the positive current collecting sheet 6 and the negative current collecting sheet 5, wherein the positive current collecting sheet 6 is connected to the aluminum shell 8, and the negative current collecting sheet 5 is connected to the negative aluminum cover 7; in the fourth step, the surface of the battery cell 4 is wrapped with insulating tape 9, and an insulating ring 11 is placed on the negative end. After being placed in the aluminum shell 8, it is grooved and sealed; in the fifth step, after the sealed battery cell 4 is baked, liquid is injected, and then the injection hole is sealed. After activation, an internal parallel supercapacitor with a height of 95 mm, a rated voltage of 2.7 V, and a capacity of 1500F is obtained.

[0039] Example 2 The difference from Example 1 is that the diameter of the center hole of the positive electrode sheet 3 and the negative electrode sheet 1 is 2 mm.

[0040] Example 3 The difference from Example 1 is that the diameter of the center hole of the positive electrode sheet 3 and the negative electrode sheet 1 is 8 mm.

[0041] Example 4 The difference from Example 2 is that the diameter of the positive electrode sheet 3 and the negative electrode sheet 1 is 56 mm, and the diameter of the cellulose separator is 58 mm. Figure 7The stacking method is used to stack the supercapacitors to form an internal parallel supercapacitor with a height of 138mm, a rated voltage of 2.7V, and a capacity of 3000F.

[0042] Example 5 The difference from Example 4 is that the diameters of the positive electrode sheet 3 and the negative electrode sheet 1 are 150 mm, and an internal parallel supercapacitor with a rated voltage of 2.7 V and a capacity of 25000 F is manufactured.

[0043] Example 6 The difference from Example 4 is that the diaphragm used is a ceramic diaphragm.

[0044] Example 7 The difference from Example 4 is that 5.5 parts of the conductive agent in the electrode slurry is a mixture of carbon black and carbon nanotubes, and the mass ratio of carbon black to carbon nanotubes is 3:1.

[0045] Example 8 This embodiment provides a method for making an internal parallel supercapacitor. The difference from the above embodiments 1 to 7 is that a negative electrode sheet 1 is prepared by combining activated carbon and graphite, and a positive electrode sheet 3 is prepared by combining activated carbon and lithium nickel cobalt manganese oxide. Specifically, in the first step, 92 parts of activated carbon and graphite (mass ratio 3:7), 3 parts of conductive agent carbon black, 2 parts of thickener CMC, 3 parts of binder SBR are mixed with deionized water to form a negative electrode slurry, which is then applied to the upper and lower surfaces of copper foil to form a surface density of 0.8g / dm 2 Similarly, 92 parts of activated carbon and lithium nickel cobalt manganese oxide (NCM523) (mass ratio 2:8), 5 parts of conductive agent carbon black, 3 parts of binder polytetrafluoroethylene (PVDF) and solvent N-methylpyrrolidone were mixed to prepare positive electrode slurry, which was applied to the upper and lower surfaces of aluminum foil to form a density of 1.7 g / dm on the upper and lower surfaces. 2 The strip-shaped coated positive electrode sheet; the second step is to roll the strip-shaped coated positive electrode sheet and the strip-shaped coated negative electrode sheet to a thickness of 280um and 300um respectively, and cut them into a positive electrode sheet 3 with a diameter of 55mm, a center hole diameter of 2mm, and a tab bow height of 3mm and a negative electrode sheet 1 with a diameter of 55.5mm, a center hole diameter of 2mm, and a tab bow height of 3mm respectively. The positive electrode sheet 3, the ceramic diaphragm with a diameter of 57.5mm, and the negative electrode sheet 1 are arranged in accordance with Figure 7A cylindrical laminated battery cell 4 is made by alternating stacking, with 200 layers. The positive electrode tabs 302 and the negative electrode tabs 102 on both sides of the battery cell 4 are shaped, and the shaped positive electrode tabs 302 and the negative electrode tabs 102 are respectively connected to the positive current collecting sheet 6 and the negative current collecting sheet 5, wherein the positive current collecting sheet 6 is connected to the aluminum shell 8, and the negative current collecting sheet 5 is connected to the negative aluminum cover 7; the surface of the battery cell 4 is wrapped with insulating tape 9, and an insulating ring 11 is placed on the negative end. After being placed in the aluminum shell 8, the battery cell 4 is grooved and sealed. After the sealed battery cell 4 is baked, an organic electrolyte is injected, and then the injection hole is sealed. After activation, an internal parallel supercapacitor with a rated voltage of 4.0V and a capacity of 15000F is made.

[0046] Example 9 The difference between this embodiment and Example 8 is that the negative electrode slurry contains 3 parts of a conductive agent, which is a mixture of carbon black and carbon nanotubes, wherein the mass ratio of carbon black to carbon nanotubes is 3:1, and the binder is 2 parts of polyacrylic acid; the positive electrode slurry contains 5 parts of a conductive agent, which is a mixture of carbon black, carbon nanotubes, and graphene, wherein the mass ratio of carbon black, carbon nanotubes, and graphene is 4:1:1.

[0047] Comparative Example 1 Mix 89 parts of activated carbon, 5.5 parts of conductive agent SP, 2 parts of thickener CMC, 3.5 parts of binder SBR with deionized water to make a slurry, and apply it to the upper and lower surfaces of aluminum foil to form a density of 0.6g / dm 3 The strip-shaped coating morphology is rolled and cut into positive and negative electrode sheets with a width of 125mm, including tabs with a width of 13mm. The tabs are then wound with a 120mm wide separator with tabs on both ends to form a cylindrical cell with a diameter of 56.5mm. The separator edge is 4mm larger than the edge of the active material layer of the positive and negative electrode sheets. After shaping and current collector welding, the cell is packaged, injected with electrolyte, and activated to produce a cylindrical double-layer supercapacitor with a height of 138mm, a rated voltage of 2.7V, and a capacity of 3000F.

[0048] Comparative Example 2 A lithium-ion hybrid supercapacitor was prepared. Specifically, in the first step, 92 parts of activated carbon and graphite (mass ratio 3:7), 3 parts of conductive agent SP, 2 parts of thickener CMC, 3 parts of binder SBR were mixed with deionized water to prepare a negative electrode slurry, which was then applied to the upper and lower surfaces of copper foil to form a surface density of 0.8 g / dm 2 Similarly, 92 parts of activated carbon and lithium nickel cobalt manganese oxide (NCM523) (mass ratio 2:8), 5 parts of conductive agent SP, 3 parts of binder PVDF and solvent N-methylpyrrolidone were mixed to prepare positive electrode slurry, which was applied to the upper and lower surfaces of aluminum foil to form a density of 1.7 g / dm on the upper and lower surfaces. 2strip-shaped coated positive electrode sheet; the second step is to roll the strip-shaped coated positive electrode sheet and the strip-shaped coated negative electrode sheet to a thickness of 280um and 300um respectively after rolling, and cut the rolled strip-shaped coated positive electrode sheet into a 123mm wide positive electrode sheet, including a positive electrode ear (13mm wide), and cut the rolled strip-shaped coated negative electrode sheet into a 125mm wide negative electrode sheet, including a negative electrode ear (13mm wide), and wind the positive electrode sheet, a 120mm wide ceramic diaphragm, and a negative electrode sheet into a battery cell with a diameter of 56.5mm. After shaping and current collector welding, the electrolyte is injected after packaging, and after activation, an internal parallel supercapacitor with a height of 138mm, a rated voltage of 4.0V, and a capacity of 15000F is made.

[0049] The main performance parameters of the supercapacitors obtained in the examples and comparative examples are shown in Table 1.

[0050] Table 1 Comparison of performance parameters between examples and comparative examples

[0051] The results show that the internal parallel supercapacitor of the present invention has obvious advantages in terms of capacity improvement and retention rate, maximum equivalent series internal resistance, cycle life, self-discharge, temperature rise at maximum continuous current, and injection efficiency.

[0052] For the electrode sheets with an internal parallel structure, the stacked structure can provide more electrolyte penetration channels. The central hole in the present invention can further help the penetration efficiency of the electrolyte. For the supercapacitors of Examples 1 to 3, the central holes of the electrode sheets (i.e., the positive electrode sheet 3 and the negative electrode sheet 1) are 0.1 mm, 2 mm, and 8 mm, respectively. The larger the central hole, the better the electrolyte penetration effect and the higher the efficiency. However, the increase in the central hole will inevitably lead to a loss of capacity. Therefore, a central hole with a diameter of 2 mm is preferred. The stacked internal parallel structure has a great advantage in improving the capacitance of the capacitor. Compared with Example 5, Example 4 can increase the capacity by increasing the size of the electrode sheet. Compared with Comparative Example 1, Comparative Example 1 is a typical winding structure. It is limited by the penetration effect of the electrolyte and is not as good as Example 4, but it has a slightly higher penetration efficiency than Example 5. Example 6 uses a diaphragm containing a ceramic coating. Compared with Example 4, the internal resistance of the capacitor is larger. Under continuous charge and discharge conditions, the temperature rise will be more obvious. Compared with Example 4, Example 7 adds carbon nanotubes to the conductive agent component, which is more advantageous under high-current charging and discharging conditions; compared with Comparative Example 1, the contact internal resistance and temperature rise are smaller under the same charging and discharging conditions. Example 8 and Comparative Example 2 are hybrid capacitors, and Example 8 is a hybrid capacitor with an internal parallel structure. Its electrostatic capacitance is higher than that of Comparative Example 2, and its internal resistance and temperature rise are both lower than Comparative Example 2. Example 9, compared with Example 8, has different components and ratios of the conductive agent and binder. Thanks to the special structure of carbon nanotubes and graphene, it combines the advantages of point, line, and surface conductivity, improving the overcurrent capacity and reducing the temperature rise during the capacitor charging and discharging process.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art may still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. An internal parallel supercapacitor, characterized in that: The battery cell (4) comprises an outer side wrapped with an insulating layer, the top and bottom of the battery cell (4) are respectively provided with a negative electrode current collecting sheet (5) and a positive electrode current collecting sheet (6), the battery cell (4) is placed in an aluminum shell (8) with an opening at the top, and the top of the aluminum shell (8) is provided with a negative electrode aluminum cover (7); The battery cell (4) is formed by stacking a negative electrode sheet (1) including a negative electrode tab (102), a separator (2), and a positive electrode sheet (3) including a positive electrode tab (302) in sequence. A central hole is provided in the middle of each of the negative electrode sheet (1) and the positive electrode sheet (3). After stacking, the negative electrode tab (102) is shaped and connected to the negative electrode current collecting sheet (5). The negative electrode current collecting sheet (5) is connected to the negative electrode aluminum cover (7). After stacking, the positive electrode tab (302) is shaped and connected to the positive electrode current collecting sheet (6). The positive electrode current collecting sheet (6) is connected to the aluminum shell (8). The battery cell (4) is soaked with an organic electrolyte.

2. The internal parallel supercapacitor according to claim 1, characterized in that: The positive electrode sheet (3) comprises a current collector and a positive electrode active material layer (301) adhered to the upper and lower surfaces of the current collector, and the exposed portion of the current collector to which the positive electrode active material layer (301) is not adhered is the positive electrode tab (302); The negative electrode sheet (1) comprises a current collector and a negative electrode active material layer (101) adhered to the upper and lower surfaces of the current collector, and the exposed portion of the current collector to which the negative electrode active material layer (101) is not adhered is the negative electrode tab (102).

3. The internal parallel supercapacitor according to claim 2, characterized in that: The raw materials for preparing the positive electrode active material layer (301) include a positive electrode active material, a conductive agent, a binder and a thickener, and the mass ratio of the positive electrode active material, the conductive agent, the binder and the thickener is (85-98): (1-8): (1-5): (0-2); The raw materials for preparing the negative electrode active material layer (101) include a negative electrode active material, a conductive agent, a binder and a thickener, and the mass ratio of the negative electrode active material, the conductive agent, the binder and the thickener is (85-97): (1-8): (1-5): (1-2).

4. The internal parallel supercapacitor according to claim 3, characterized in that: The positive electrode active material is one or both of activated carbon and lithium-based positive electrode materials; The lithium-based positive electrode material is lithium iron phosphate, lithium nickel cobalt oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide or lithium manganese oxide.

5. The internal parallel supercapacitor according to claim 3, characterized in that: The negative electrode active material is one or both of activated carbon and pre-lithiation negative electrode material; The pre-lithiation negative electrode material is graphite, silicon carbon or silicon oxide.

6. The internal parallel supercapacitor according to claim 3, characterized in that: The binder is one or a combination of two of polyacrylic acid, styrene-butadiene rubber and polytetrafluoroethylene; The thickener is sodium carboxymethyl cellulose; The conductive agent is one or more of carbon black, acetylene black, carbon nanotubes, and graphene; The current collector is one or both of aluminum foil and copper foil.

7. The internal parallel supercapacitor according to claim 3, characterized in that: The edge of the negative electrode active material layer (101) is larger than the edge of the positive electrode active material layer (301) by 0-2 mm, and the edge of the separator (2) is larger than the edge of the negative electrode active material layer (101) by 1-4 mm.

8. The internal parallel supercapacitor according to claim 1, characterized in that: The diameter of the central hole in the middle of the negative electrode sheet (1) and the positive electrode sheet (3) is 0.1 mm to 8 mm.

9. The internal parallel supercapacitor according to claim 1, characterized in that: The separator is one of a cellulose separator, a non-woven fabric separator, a polypropylene separator, a polytetrafluoroethylene separator and a ceramic separator.

10. A method for manufacturing an internal parallel supercapacitor according to any one of claims 1 to 9, characterized in that: include: preparing strip-shaped coated positive electrode sheets and strip-shaped coated negative electrode sheets for processing positive electrode sheets (3) and negative electrode sheets (1), respectively; Based on the strip-shaped coated positive electrode sheet and the strip-shaped coated negative electrode sheet, a positive electrode sheet (3) and a negative electrode sheet (1) are obtained by cutting; stacking the negative electrode sheet (1), the separator (2) and the positive electrode sheet (3) in sequence; After stacking the negative electrode tabs (102) of the negative electrode sheets (1), the negative electrode tabs (102) are shaped and connected to the negative electrode current collector (5); after stacking the positive electrode tabs (302) of the positive electrode sheets (3), the positive electrode tabs (302) are shaped and connected to the positive electrode current collector (6) to form a battery cell (4); The positive electrode current collector (6) of the battery cell (4) is connected to the aluminum shell (8), and the negative electrode current collector (5) is connected to the negative electrode aluminum cover (7). The interior of the battery cell (4) is evenly infiltrated with an organic electrolyte and sealed in the area surrounded by the aluminum shell (8) and the negative electrode aluminum cover (7), thereby completing the production of an internal parallel supercapacitor.

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