Capacitor electrode sheet and preparation method therefor, and capacitor using same

Abstract

Provided in the present application are a capacitor electrode sheet and a preparation method therefor, and a capacitor using same. The capacitor electrode sheet comprises an electrode active material layer and a conductive adhesive layer compounded with the electrode active material layer. The capacitor electrode sheet has good conductivity and mechanical properties, and can improve the energy density and cyclic stability of a capacitor using the capacitor electrode sheet.

Description

A capacitor electrode sheet, a preparation method thereof, and a capacitor using the same

[0001] This application claims priority to the Chinese patent application No. 202510245673.1, filed on March 3, 2025, to the Chinese Patent Office, the whole content of the above application being incorporated herein by reference. TECHNICAL FIELD

[0002] The present application belongs to the field of capacitors, and relates to a capacitor electrode sheet, a preparation method thereof, and a capacitor using the same. BACKGROUND

[0003] Supercapacitors, also known as double-layer capacitors, electrochemical capacitors, gold capacitors or farad capacitors, are a new type of energy storage device between traditional capacitors and batteries. Supercapacitors can be regarded as two non-reactive electrode plates suspended in an electrolyte. When a voltage is applied to the electrode plates, the positive electrode plate attracts negative ions in the electrolyte, and the negative electrode plate attracts positive ions. In fact, two capacitive storage layers are formed, and the separated positive ions are near the negative electrode plate, and the negative ions are near the positive electrode plate. Therefore, supercapacitors are a new type of energy storage material, which stand out due to a series of characteristics such as long cycle life, high power density, wide operating temperature range, etc. The performance of supercapacitors depends greatly on the composition of the electrode material and the design of the electrode structure. TECHNICAL PROBLEM

[0004] In order to improve the structural stability of each element in the capacitor and avoid relative displacement between the electrode sheet and the capacitor shell during operation, the electrode sheet and the capacitor shell are usually welded together. However, in actual operation, there are often poor welding effects such as welding hole, welding protrusion, etc., which seriously affect the further development and application of the capacitor. On the one hand, the welding hole reduces the welding connection strength and the conductivity, affecting the normal operation of the capacitor; on the other hand, the welding protrusion is too high, which increases the risk of the diaphragm being pierced, threatening the safety performance of the capacitor. SOLUTION

[0005] The present application provides a capacitor electrode sheet, a preparation method thereof, and a capacitor using the same. The capacitor electrode sheet has good conductivity and mechanical properties, which can improve the energy density and cycle stability of the capacitor using the same.

[0006] According to a first aspect of the present application, a capacitor electrode sheet is provided, which comprises an electrode active material layer and a conductive adhesive layer combined with the electrode active material layer.

[0007] According to another aspect of the present application, there is provided a method for preparing the capacitor electrode sheet as described above, comprising the following operations: mixing a binder, a conductive agent and a solvent to prepare a conductive paste, coating the conductive paste on the surface of the electrode active material layer, and curing and rolling to obtain the capacitor electrode sheet.

[0008] According to another aspect of the present application, there is provided a capacitor comprising the capacitor electrode sheet as described above, or comprising the capacitor electrode sheet prepared by the method as described above. The capacitor as described above has a simple structure between the electrode sheet layers and a small thickness, which can effectively improve the energy density of the capacitor, reduce the possibility of self-discharge of the capacitor, prolong the endurance, and has high reliability and safety, is convenient to disassemble, is conducive to batch production, realizes miniaturization and ultra-thin, and is suitable for ultra-thin terminal products. Advantages

[0009] The capacitor electrode sheet provided by the present application has good conductivity and mechanical properties, and can improve the energy density and cycle stability of the capacitor using the same.

[0010] Other aspects can become apparent from the following drawings and detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0011] FIG. 1 is a structural schematic diagram of the negative electrode sheet provided by the experimental group 1A;

[0012] FIG. 2 is a structural schematic diagram of the positive electrode sheet provided by the experimental group 1A;

[0013] FIG. 3 is a structural schematic diagram of the capacitor provided by the experimental group 1A;

[0014] The corresponding relationship of the above-mentioned reference numerals is as follows: 1. positive active material layer, 2. negative active material layer, 3. separator, 4. insulating rubber ring, 5. cover, 6. shell, 7. positive conductive glue layer, 8. negative conductive glue layer. Embodiments of the present application

[0015] According to a first aspect of the present application, there is provided a capacitor electrode sheet comprising an electrode active material layer and a conductive glue layer combined with the electrode active material layer.

[0016] The capacitor electrode sheet provided by the application comprises a conductive adhesive layer and an electrode active material layer. The conductivity and mechanical properties of the conductive adhesive layer are utilized to improve the cycle stability of the capacitor electrode sheet and the energy density of the capacitor. On the one hand, the conductive adhesive layer is firmly bonded with the electrode active material layer, which not only reduces the impedance of the capacitor electrode sheet, but also improves the flexibility of the capacitor electrode sheet, so that the capacitor electrode sheet can maintain structural integrity under a certain degree of bending and twisting, the structural stability and safety of the capacitor electrode sheet are improved, the probability of powder falling and cracking of the electrode active coating is reduced, the cycle performance of the capacitor is improved, and the service life is prolonged. On the other hand, the adhesion of the conductive adhesive layer in the capacitor electrode sheet can realize the connection of the capacitor electrode sheet and the shell of the capacitor, abandon the traditional welding method, simplify the preparation process of the electrode sheet, improve the flexible properties and high energy density of the capacitor electrode sheet. Moreover, the conductive adhesive layer can make the active material layer fully contact with the structural part shell, and because the conductive adhesive layer has good conductivity, it can also play the role of current collection.

[0017] In addition, it should be noted that if the electrode sheet comprises a conductive adhesive layer, a current collector and an electrode active material layer arranged in sequence, although the conductive adhesive layer can also adhere the electrode sheet to other capacitor elements, when the capacitor is subjected to external force impact or falling, the pulling force exerted by the capacitor shell on the conductive adhesive layer is greater than the pulling force exerted by the current collector on the double-sided adhesive tape. The difference between the above-mentioned pulling forces is easy to cause the conductive adhesive layer to be pasted on one side of the current collector to be edge-broken and torn, resulting in burrs on the current collector, which is easy to cause sharp-point discharge with the metal shell of the capacitor, causing short circuit of the capacitor. However, the capacitor electrode sheet provided by the present application does not use a current collector. Even if the conductive layer pasted on one side of the electrode active material layer is edge-broken and torn due to the difference between the pulling forces, the electrode active material layer is not easy to produce burrs, and the burrs will not cause short circuit. Therefore, the capacitor electrode sheet provided by the present application also improves the safety and anti-falling effect of the capacitor using the same.

[0018] Optionally, the capacitor electrode sheet is composed of an electrode active material layer and a conductive adhesive layer combined with the electrode active material layer.

[0019] Optionally, the conductive adhesive layer is arranged on at least one side of the electrode active material layer.

[0020] Optionally, the conductive adhesive layer comprises a binder and a conductive agent, and the mass ratio of the binder to the conductive agent is 0.5-4; 96-99.5. By adjusting the ratio of the binder to the conductive agent in the conductive adhesive layer, the conductivity of the capacitor electrode sheet can be improved, the transmission efficiency of the carriers can be increased, and the fast-charging performance of the capacitor electrode sheet can be improved. In addition, the conductive adhesive layer can still maintain good adhesion and structural stability even after long-term immersion in electrolyte, and can reliably fix the capacitor electrode sheet without dissolving by-products that affect the normal operation of the battery.

[0021] Optionally, the conductive agent comprises at least one of conductive carbon black, carbon nanotubes, graphene, and carbon fibers.

[0022] Optionally, the binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, sodium carboxymethyl cellulose, and butadiene styrene rubber.

[0023] Optionally, in the conductive adhesive layer, the specific surface area of the conductive agent is 40-100 m 2 / g, and the median particle size D 50 of the conductive agent is 10-100 nm. The conductive adhesive layer prepared by using the conductive agent satisfying the above requirements has good conductivity and can achieve a low resistance value. By adjusting the specific surface area and the median particle size D 50 of the conductive agent, the conductive agent can be uniformly dispersed in the conductive adhesive layer to form an efficient conductive path, meet the extremely strict conductive requirements of the capacitor, and enable the conductive agent to be bonded in the conductive adhesive layer so that the conductive agent does not easily fall off from the surface of the conductive adhesive layer.

[0024] Optionally, the thickness of the conductive adhesive layer is 10-100 μm. By adjusting the thickness of the conductive adhesive layer, the adhesion between the conductive adhesive layer and the electrode active material layer can be enhanced, the impedance can be reduced, the electrolyte resistance of the conductive adhesive layer can be improved, the structural stability of the capacitor can be improved, and the specific energy of the capacitor electrode sheet can be increased to achieve light weight.

[0025] Optionally, the electrode active material layer comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder, and the negative electrode active material comprises at least one of a lithium-containing oxide negative electrode material, a carbon-based negative electrode material, and a silicon-based negative electrode material.

[0026] Optionally, the lithium-containing oxide negative electrode material comprises at least one of lithium titanate, lithium vanadate, and lithium titanium silicate.

[0027] Optionally, the carbon-based negative electrode material comprises at least one of graphite, mesocarbon microbeads, soft carbon, hard carbon, and graphene.

[0028] Optionally, the silicon-based negative electrode material comprises at least one of silicon, silicon oxide, and silicon / carbon composite material.

[0029] Optionally, the electrode active material layer further comprises a porous carbon electrode material, and the specific surface area of the porous carbon electrode material is 1400-2000 m 2 By adding the porous carbon electrode material with high specific surface area to the negative electrode sheet of the capacitor to form an electric double layer structure, the energy density of the capacitor is improved.

[0030] Optionally, the porous carbon electrode material comprises porous activated carbon and / or biomass carbon.

[0031] Optionally, the median particle size D 50 of the porous carbon electrode material is 3-10 μm.

[0032] Optionally, in the electrode active material layer, the mass fraction of the negative electrode active material is 60-98%.

[0033] Optionally, in the electrode active material layer, the mass fraction of the carbon electrode material is 2-20%.

[0034] Optionally, in the electrode active material layer, the mass fraction of the negative electrode conductive agent is 1-8%.

[0035] Optionally, in the electrode active material layer, the mass fraction of the negative electrode binder is 1-8%.

[0036] Optionally, the electrode active material layer comprises a positive electrode active material, a positive electrode conductive agent and a positive electrode binder, and the positive electrode active material comprises a lithium-containing compound.

[0037] Optionally, the lithium-containing compound comprises at least one of a layered transition metal oxide, a polyanion compound and a spinel compound.

[0038] Optionally, when the capacitor electrode sheet is a negative electrode, the thickness of the electrode active material layer is 200-2000 μm.

[0039] Optionally, when the capacitor electrode sheet is a positive electrode, the thickness of the electrode active material layer is 100-1000 μm.

[0040] According to another aspect of the present application, a preparation method of the above capacitor electrode sheet is provided, comprising the following operations: mixing a binder, a conductive agent and a solvent to prepare a conductive paste, coating the conductive paste on the surface of the electrode active material layer, and curing and rolling to obtain the capacitor electrode sheet.

[0041] Optionally, when the thickness of the electrode active material layer is >200 μm, a dry method is used for preparation.

[0042] Optionally, the dry method comprises the following steps: mixing raw materials for preparing the electrode active material layer in a certain proportion to obtain electrode material dry powder; and then forming the electrode active material layer with a desired thickness by heating and extruding the electrode material dry powder.

[0043] Optionally, when the thickness of the electrode active material layer is less than or equal to 200 microns, the wet method is used.

[0044] Optionally, the wet method comprises the following steps: mixing the positive electrode binder or the negative electrode binder with a solvent in a certain proportion to obtain electrode glue solution; then mixing the remaining raw materials for preparing the electrode active material layer with the electrode glue solution to obtain wet slurry; and finally coating the wet slurry on a flat surface and performing baking treatment to obtain the electrode active material layer.

[0045] According to another aspect of the present application, a capacitor is provided, which comprises the capacitor electrode sheet described above, or comprises the capacitor electrode sheet prepared by the preparation method described above. The capacitor electrode sheet described above has a simple interlayer structure and a small thickness, which can effectively improve the energy density of the capacitor, reduce the possibility of self-discharge of the capacitor, prolong the endurance, and has high reliability and safety, is easy to disassemble, is conducive to mass production, realizes miniaturization and ultrathin, and is suitable for ultrathin terminal products.

[0046] Optionally, the capacitor comprises an insulatingly connected shell and a cover, the shell and the cover form a containing cavity, the containing cavity is sequentially stacked with a positive electrode sheet, a diaphragm and a negative electrode sheet, the positive electrode sheet is at least partially connected to the shell, the negative electrode sheet is at least partially connected to the cover, the positive electrode sheet and / or the negative electrode sheet comprises the capacitor electrode sheet, and the conductive adhesive layer of the capacitor electrode sheet is arranged away from the diaphragm. Compared with the traditional electrode sheet in the form of multiple stacked sheets or winding, the capacitor described above respectively uses a single positive electrode sheet and a single negative electrode sheet, which can greatly improve the energy density of the capacitor, and has simple production process, high production efficiency, is conducive to mass production, and is suitable for ultrathin products.

[0047] Optionally, the negative electrode sheet is the capacitor electrode sheet, and the conductive adhesive layer of the capacitor electrode sheet is connected to the cover.

[0048] Optionally, the positive electrode sheet is the capacitor electrode sheet, and the conductive adhesive layer of the capacitor electrode sheet is connected to the shell.

[0049] Optionally, the containing cavity is also filled with electrolyte.

[0050] Optionally, the shell is connected to the cover through an insulating component.

[0051] Optionally, the shell is buckled to the cover through an insulating component.

[0052] Optionally, the insulating component is arranged in the shell, and the cover is buckled to the insulating component.

[0053] Optionally, the insulating component is an insulating rubber ring.

[0054] Optionally, the diaphragm comprises a polymer diaphragm, a non-woven diaphragm, or a glass fiber diaphragm.

[0055] Optionally, the shell is made of stainless steel.

[0056] Optionally, the cover is made of stainless steel.

[0057] Optionally, the insulating component is made of at least one of polypropylene, polyphenylene sulfide, or polyether ether ketone.

[0058] Optionally, the electrolyte comprises an organic solvent and a lithium salt.

[0059] Optionally, the organic solvent comprises a carbonate solvent and / or an ether solvent.

[0060] Optionally, the lithium salt comprises at least one of LiPF6, LiTFSI, LiFSI, LiBOB, or LiBF4.

[0061] Optionally, the area ratio of the conductive adhesive layer to the electrode active material layer is 0.95-1.05:0.95-1.05.

[0062] Optionally, the area ratio of the conductive adhesive layer to the electrode active material layer is 1:1.

[0063] Optionally, the capacitor electrode sheet is circular, and the diameter ratio of the conductive adhesive layer to the electrode active material layer is 0.95-1.05:0.95-1.05.

[0064] Optionally, the capacitor electrode sheet is circular, and the diameter ratio of the conductive adhesive layer to the electrode active material layer is 1:1.

[0065] Optionally, the diameter of the capacitor is 10-24 mm.

[0066] Optionally, the thickness of the capacitor is 1.6-5 mm.

[0067] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments and examples in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application. Embodiment 1

[0068] Experimental group 1A

[0069] The experiment group provides a capacitor, which comprises a positive plate, a negative plate, a diaphragm 3, an insulating rubber ring 4, a shell 6, and a cover 5. The positive plate and the negative plate are both capacitor electrode plates.

[0070] 1. The negative plate

[0071] As shown in FIG. 1, the negative plate is composed of a negative active material layer 2 and a negative conductive adhesive layer 8 compounded with the negative active material layer 2. The raw material composition of the negative plate is shown in the following table, wherein the thickness of the negative active material layer 2 is 1500 μm, the thickness of the negative conductive adhesive layer 8 is 50 μm, the negative plate is circular, the diameter ratio of the negative conductive adhesive layer 8 to the negative active material layer 2 is 1:1, and the area ratio of the negative active material layer 2 to the negative conductive adhesive layer 8 is 1:1.

[0072] Table 1. Raw material composition of the negative active material layer 2 and the negative conductive adhesive layer 8

[0073]

[0074] In the raw material for preparing the negative active material layer 2, the lithium-containing oxide is lithium titanate, the specific surface area of the porous activated carbon is in the range of 1700-1800 m 2 / g, and the median particle size D 50 is in the range of 6-7 μm; the specific surface area of the negative conductive agent is in the range of 50-60 m 2 / g, and the median particle size D 50 is in the range of 80-90 nm. In the raw material for preparing the negative conductive adhesive layer 8, the specific surface area of the conductive carbon black is in the range of 70-90 m 2 / g, and the median particle size D 50 is in the range of 10-30 nm.

[0075] The preparation method of the negative plate comprises the following operations:

[0076] Preparation of the negative active material layer 2: the raw material for preparing the negative active material layer 2 is mixed in proportion to obtain a negative material dry powder, and the negative material dry powder is formed into a negative active material layer 2 with a desired thickness by means of heating and extrusion.

[0077] Preparation of the negative conductive adhesive layer 8: the binder, the conductive agent, and the solvent are mixed to prepare a conductive adhesive, the conductive adhesive is coated on the surface of the negative active material layer 2, and solidification and rolling are performed to obtain the negative plate.

[0078] 2. The positive plate

[0079] As shown in Fig. 2, the positive electrode sheet is composed of a positive electrode active material layer 1 and a positive electrode conductive adhesive layer 7 compounded with the positive electrode active material layer 1. The raw material composition of the positive electrode active material layer 1 and the positive electrode conductive adhesive layer 7 is shown in the following table, wherein the thickness of the positive electrode active material layer 1 is 800 μm, the thickness of the positive electrode conductive adhesive layer 7 is 50 μm, the positive electrode sheet is circular, the diameter ratio of the positive electrode conductive adhesive layer 7 to the positive electrode active material layer 1 is 1:1, and the area ratio of the positive electrode active material layer 1 to the positive electrode conductive adhesive layer 7 is 1:1.

[0080] Table 2. Raw material composition of the positive electrode active material layer 1 and the positive electrode conductive adhesive layer 7

[0081]

[0082] In the raw material for preparing the positive electrode active material layer 1, the specific surface area of the positive electrode conductive agent is in the range of 50-60 m 2 / g, and the median particle size D 50 is in the range of 80-90 nm. In the raw material for preparing the positive electrode conductive adhesive layer 7, the specific surface area of the conductive carbon black is in the range of 70-90 m 2 / g, and the median particle size D 50 is in the range of 10-30 nm.

[0083] The method for preparing the positive electrode sheet comprises the following operations:

[0084] Preparation of the positive electrode active material layer 1: the raw material for preparing the positive electrode active material layer 1 is mixed in proportion to obtain a dry positive electrode material powder, and the dry positive electrode material powder is formed into a positive electrode active material layer 1 with a desired thickness by means of heated extrusion.

[0085] Preparation of the positive electrode conductive adhesive layer 7: the binder, the conductive agent and the solvent are mixed to prepare a conductive adhesive, which is coated on the surface of the positive electrode active material layer 1, and then solidified and rolled to obtain the positive electrode sheet.

[0086] 3. Capacitor

[0087] As shown in Fig. 3, the shell 6 and the cover 5 form a containing cavity, in which the positive electrode sheet, the separator 3 and the negative electrode sheet are sequentially stacked, with the separator 3 being located between the positive electrode sheet and the negative electrode sheet; the cover 5 and the shell 6 are separated by the insulating rubber ring 4; the positive electrode conductive adhesive layer 7 of the positive electrode sheet is arranged to face away from the separator, and at least partially connects the shell 6; the negative electrode conductive adhesive layer 8 of the negative electrode sheet is arranged to face away from the separator, and at least partially connects the cover 5; the insulating rubber ring 4 is arranged in the shell 6, and the cover 5 is buckled to the insulating rubber ring 4.

[0088] The shell 6 is made of stainless steel, the cover 5 is made of stainless steel, and the insulating rubber ring 4 is made of polypropylene. The accommodation cavity is also filled with electrolyte, and the electrolyte includes LiPF6, EC, DMC, and EMC.

[0089] The size specification of the capacitor provided in this embodiment is 1016 (10 mm in diameter and 1.6 mm in thickness). In other embodiments, the size specification of the capacitor includes but is not limited to 1016 (10 mm in diameter and 1.6 mm in thickness), 1216 (12 mm in diameter and 1.6 mm in thickness), 2016 (20 mm in diameter and 1.6 mm in thickness), 2032 (20 mm in diameter and 3.2 mm in thickness), and 2450 (24 mm in diameter and 5 mm in thickness).

[0090] Comparative Group 1A

[0091] This comparative group refers to the preparation method provided in experimental group 1A to prepare a capacitor. The difference between this comparative group and experimental group 1A is that the thickness of the aluminum foil in the negative electrode conductive adhesive layer 8 is 180 μm, and the thickness of the aluminum foil in the positive electrode conductive adhesive layer 7 is 180 μm. At the same time, in the process of preparing the capacitor, the aluminum foil in the negative electrode is connected with the cover 5 by welding, and the aluminum foil in the positive electrode is connected with the shell 6 by welding. The rest of the raw material ratio, preparation method and experimental group 1A are strictly the same.

[0092] Comparative Group 2A

[0093] This comparative group refers to the preparation method provided in experimental group 1A to prepare a capacitor. The difference between this comparative group and experimental group 1A is that the negative electrode sheet includes the negative electrode conductive adhesive layer 8, the negative electrode current collector, and the negative electrode active material layer 2 arranged in sequence, and the negative electrode current collector is made of aluminum foil with a thickness of 180 μm; the positive electrode sheet includes the positive electrode conductive adhesive layer 7, the positive electrode current collector, and the positive electrode active material layer 1 arranged in sequence, and the positive electrode current collector is made of aluminum foil with a thickness of 180 μm. The rest of the raw material ratio, preparation method and experimental group 1A are strictly the same, especially the thickness and component composition of the negative electrode conductive adhesive layer 8, the negative electrode active material layer 2, the positive electrode conductive adhesive layer 7 and the positive electrode active material layer 1 are strictly the same as experimental group 1A.

[0094] Comparative Group 3A

[0095] The comparative group provides a preparation method of the capacitor provided by the experimental group 1A. The difference between the comparative group and the experimental group 1A is that the thickness of the aluminum-plated film current collector is 10 μm instead of the negative conductive adhesive layer 8 in the experimental group 1A, and the thickness of the aluminum-plated film current collector is 10 μm instead of the positive conductive adhesive layer 7 in the experimental group 1A. At the same time, in the process of preparing the capacitor, the aluminum-plated film current collector in the negative electrode is connected with the cover 5 by welding, and the aluminum-plated film current collector in the positive electrode is connected with the shell 6 by welding. The rest of the raw material ratio, preparation method and experimental group 1A are strictly the same. Test Example 1

[0096] Test object: The capacitor provided by each experimental group and the comparative group in Example 1.

[0097] Test item and test method:

[0098] (1) Capacity test: The constant current discharge method is used, and the capacitance deviation should not be less than 80% of the rated capacitance and not more than 180%, that is, the discharge capacity should be between 0.352~0.792F, and the larger the value in the range represents the better the electrical performance of the capacitor; the capacitor is connected to a direct current circuit with a constant current / constant voltage source, and after the constant current / constant voltage source reaches the rated voltage UR, it is charged for 30 min, and then the capacitor is connected to a circuit with a constant current discharge device to discharge at a constant current I (I=0.1±0.03C), and the voltage across the capacitor is measured, and the time is counted from U1=0.8UR to t1, and the time is stopped from U2=0.4UR to t2, and the discharge capacity value is calculated by the formula C=I(t2-t1) / U1-U2.

[0099] (2) ESR test: AC current test is used, and an internal resistance tester is used for measurement, and the smaller the ESR represents the better the electrical performance of the capacitor.

[0100] Test results: as shown in the following table.

[0101] Table 3. Test data measured by the test example and the structure of each test object

[0102]

[0103] Result analysis:

[0104] By comparing the performance of the capacitors provided by the experimental group 1A and the comparative groups 1A~3A, it can be found that when the capacitor uses the capacitor electrode sheet including the electrode active material layer and the conductive adhesive layer combined with the electrode active material layer, the capacitor has larger capacity and lower ESR impedance, that is, the capacitor has excellent energy density and electrochemical performance.

[0105] Comparing the capacitor provided by the experimental group 1A with the capacitor provided by the comparative group 1A and the comparative group 3A, it can be found that, in the process of preparing the capacitor of the experimental group 1A, the traditional welding process is abandoned, the stress concentration phenomenon between the current collector and the capacitor shell is reduced, and the possibility of structural weak points is reduced, which is embodied in that the ESR impedance of the capacitor of the experimental group 1A is smaller.

[0106] Comparing the capacitor provided by the experimental group 1A with the capacitor provided by the comparative group 2A, it can be found that, in the capacitor provided by the comparative group 2A, the electrode sheet containing both the metal current collector and the conductive adhesive layer is adopted, and the electrode sheet has a heterogeneous material contact surface between the electrode active material layer and the metal current collector and a heterogeneous material contact surface between the metal current collector and the conductive adhesive layer, that is, there are at least two layers of heterogeneous material contact surfaces, while in the capacitor provided by the experimental group 1A, the electrode sheet has only one layer of heterogeneous material contact surface, which is embodied in that the ESR impedance of the capacitor of the experimental group 1A is smaller. At the same time, it is found in the actual test results that the capacitor provided by the experimental group 1A shows excellent safety and anti-drop performance in the 1.8m drop test. The capacitor of the experimental group 1A still has good structural stability and electrochemical performance after the drop test, and is not easy to short circuit, while the capacitor provided by the comparative group 2A has uneven electric field distribution and local overheating after the drop test. Example 2

[0107] Experimental group 1B

[0108] In this experimental group, a capacitor is prepared according to the preparation method provided by the experimental group 1A, and the difference between this experimental group and the experimental group 1A is that, in the process of preparing the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8, the feeding amount between the conductive agent and the binder is adjusted, so that the mass ratio of the conductive agent to the binder is 0.3:99.7. The rest of the raw material ratio, preparation method and experimental group 1A are strictly the same.

[0109] Experimental group 2B

[0110] In this experimental group, a capacitor is prepared according to the preparation method provided by the experimental group 1A, and the difference between this experimental group and the experimental group 1A is that, in the process of preparing the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8, the feeding amount between the conductive agent and the binder is adjusted, so that the mass ratio of the conductive agent to the binder is 0.5:99.5. The rest of the raw material ratio, preparation method and experimental group 1A are strictly the same.

[0111] Experimental group 3B

[0112] The present experimental group refers to the preparation method provided by experimental group 1A to prepare a capacitor. The difference between the present experimental group and experimental group 1A is that, in the process of preparing the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8, the amount of conductive agent and binder is adjusted, so that the mass ratio of conductive agent to binder is 4:96. The remaining raw material ratio, preparation method and experimental group 1A are strictly the same.

[0113] Experimental group 4B

[0114] The present experimental group refers to the preparation method provided by experimental group 1A to prepare a capacitor. The difference between the present experimental group and experimental group 1A is that, in the process of preparing the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8, the amount of conductive agent and binder is adjusted, so that the mass ratio of conductive agent to binder is 4:96. The remaining raw material ratio, preparation method and experimental group 1A are strictly the same. Test example 2

[0115] Test subjects: capacitors provided by experimental group 1A and each experimental group in example 2.

[0116] Test items and test methods:

[0117] (1) Capacity test: strictly the same as test example 1.

[0118] (2) ESR test: strictly the same as test example 1.

[0119] Test results: as shown in the following table:

[0120] Table 4. Test data measured by the present test example and the ratio of each test object

[0121]

[0122] Result analysis:

[0123] By comparing experimental groups 1C~4C with the capacitors provided by experimental group 1A, it can be found that, with the decrease of the content of conductive agent in the conductive adhesive layer, the capacity of the capacitor presents a trend of first increasing and then decreasing, and the ESR impedance of the capacitor presents a trend of first decreasing and then increasing. When the mass ratio of binder to conductive agent in the conductive adhesive layer is 0.5~4:96~99.5, the capacitor has both large capacity and low ESR impedance. Example 3

[0124] Experimental group 1C

[0125] The experimental group refers to the preparation method provided by the experimental group 1A to prepare a capacitor. The difference between the experimental group and the experimental group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 is adjusted to 10 μm. The remaining raw material ratio, preparation method and experimental group 1A are strictly kept consistent.

[0126] Experimental group 2C

[0127] The experimental group refers to the preparation method provided by the experimental group 1A to prepare a capacitor. The difference between the experimental group and the experimental group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 is adjusted to 30 μm. The remaining raw material ratio, preparation method and experimental group 1A are strictly kept consistent.

[0128] Experimental group 3C

[0129] The experimental group refers to the preparation method provided by the experimental group 1A to prepare a capacitor. The difference between the experimental group and the experimental group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 is adjusted to 70 μm. The remaining raw material ratio, preparation method and experimental group 1A are strictly kept consistent.

[0130] Experimental group 4C

[0131] The experimental group refers to the preparation method provided by the experimental group 1A to prepare a capacitor. The difference between the experimental group and the experimental group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 is adjusted to 100 μm. The remaining raw material ratio, preparation method and experimental group 1A are strictly kept consistent.

[0132] Experimental group 5C

[0133] The experimental group refers to the preparation method provided by the experimental group 1A to prepare a capacitor. The difference between the experimental group and the experimental group 1A is that in the process of preparing the negative active material layer 2, an equal amount of negative conductive agent is used instead of the porous carbon electrode material in the experimental group 1A. The remaining raw material ratio, preparation method and experimental group 1A are strictly kept consistent. Test example 3

[0134] Test object: The capacitors provided by the experimental group 1A and each experimental group in example 3.

[0135] Test items and test methods:

[0136] (1) Capacity test: strictly consistent with test example 1.

[0137] (2) ESR test: strictly consistent with test example 1.

[0138] Test results: as shown in the following table:

[0139] Table 5. Test data and variable parameters of each test object measured in this test example

[0140]

[0141] Result analysis:

[0142] Comparing the capacitors provided by experimental groups 1C-4C with the capacitors provided by experimental group 1A, it can be found that, with the increase of the thickness of the conductive adhesive layer, the capacity of the capacitor presents a trend of first increasing and then decreasing, and the ESR impedance of the capacitor presents a trend of first decreasing and then increasing, wherein the impedance of the capacitor of experimental group 1A is the smallest, only 1.52Ω.

[0143] Comparing the capacitors provided by experimental group 1A with the capacitors provided by experimental group 5C, it can be found that, when the porous carbon electrode material is used in the negative active coating, the energy density of the capacitor is higher, the capacity of the capacitor is larger, and the ESR impedance of the capacitor is smaller.

Claims

1. A capacitor electrode sheet, comprising an electrode active material layer, and a conductive adhesive layer compounded with the electrode active material layer.

2. The capacitor electrode sheet of claim 1, wherein, The conductive adhesive layer comprises a binder and a conductive agent, and the mass ratio of the binder to the conductive agent is 0.5-4:96-99.

5.

3. The capacitor electrode sheet of claim 2, wherein, In the conductive adhesive layer, the specific surface area of the conductive agent is 40-100 m 2 / g, and the median particle size D 50 of the conductive agent is 10-100 nm.

4. The capacitor electrode sheet of claim 1, wherein, The thickness of the conductive adhesive layer is 10-100 μm.

5. The capacitor electrode sheet of claim 1, wherein, The electrode active material layer comprises a negative electrode active material, a negative electrode conductive agent and a negative electrode binder, and the negative electrode active material comprises at least one of a lithium-containing oxide negative electrode material, a carbon-based negative electrode material and a silicon-based negative electrode material.

6. The capacitor electrode sheet of claim 5, wherein, The electrode active material layer further comprises a porous carbon electrode material having a specific surface area of 1400 to 2000 m 2 / g.

7. The capacitor electrode sheet of claim 1, wherein, The electrode active material layer comprises a positive electrode active material, a positive electrode conductive agent and a positive electrode binder, and the positive electrode active material comprises a lithium-containing compound. 8.A method for preparing the capacitor electrode sheet according to any one of claims 1-7, comprising the following steps: mixing a binder, a conductive agent and a solvent to prepare a conductive adhesive, coating the conductive adhesive on the surface of an electrode active material layer, and curing and rolling to obtain the capacitor electrode sheet.

9. A capacitor, wherein, The capacitor comprises the capacitor electrode sheet according to any one of claims 1-7, or comprises the capacitor electrode sheet prepared by the method according to claim 8. 10.The capacitor according to claim 9, comprising an insulating connected shell and a cover, the shell and the cover form a containing cavity, and the containing cavity is sequentially provided with a positive electrode sheet, a diaphragm and a negative electrode sheet, the positive electrode sheet is at least partially connected to the shell, and the negative electrode sheet is at least partially connected to the cover; the positive electrode sheet and / or the negative electrode sheet comprises the capacitor electrode sheet, and the conductive adhesive layer of the capacitor electrode sheet is arranged away from the diaphragm.

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