Capacitor electrode plate and preparation method thereof, and capacitor applying capacitor electrode plate

Abstract

The invention provides a capacitor electrode plate, a preparation method thereof and a capacitor using the capacitor electrode plate. The capacitor electrode plate comprises an electrode active material layer and a conductive adhesive layer compounded with the electrode active material layer. The capacitor electrode plate has good conductivity and mechanical properties, and can improve the energy density and cycling stability of a capacitor using the capacitor electrode plate.

Description

Technical Field

[0001] The present invention belongs to the field of capacitors, and relates to a capacitor electrode sheet, a preparation method thereof, and a capacitor using the same. Background Art

[0002] A supercapacitor, also known as an electric double-layer capacitor, an electrochemical capacitor, a gold capacitor or a farad capacitor, is a new type of energy storage device between traditional capacitors and storage batteries. A supercapacitor can be regarded as two non-reactive electrode plates suspended in an electrolyte. When an electric charge is applied to the electrode plates, the positive electrode plate attracts negative ions in the electrolyte, and the negative electrode plate attracts positive ions, actually forming two capacitive storage layers. The separated positive ions are near the negative electrode plate, and the negative ions are near the positive electrode plate. Therefore, a supercapacitor is a new type of energy storage material, which stands out due to a series of characteristics such as a long cycle life, a high power density, and a wide working temperature range. The performance of a supercapacitor depends to a great extent on the composition of the electrode material and the design of the electrode structure.

[0003] In order to improve the structural stability of each component in the capacitor and avoid relative displacement between the electrode sheet and the capacitor housing during operation, the electrode sheet and the capacitor housing are usually welded together. However, in actual operation, poor welding effects such as solder joint perforation and too high solder joint protrusion often occur, which seriously affects the further development and application of the capacitor. On the one hand, solder joint perforation will reduce the welding connection strength and electrical conductivity, affecting the normal operation of the capacitor; on the other hand, too high solder joint protrusion will increase the risk of piercing the diaphragm, threatening the safety performance of the capacitor. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a capacitor electrode sheet, a preparation method thereof, and a capacitor using the same. The capacitor electrode sheet has good electrical conductivity and mechanical properties, and can improve the energy density and cycle stability of the capacitor using the same.

[0005] According to the first aspect of the present invention, there is provided a capacitor electrode sheet, which includes an electrode active material layer and a conductive adhesive layer compounded with the electrode active material layer.

[0006] The capacitor electrode sheet provided by the present invention includes a conductive adhesive layer and an electrode active material layer. By utilizing the conductivity and mechanical properties of the conductive adhesive layer, the cycle stability of the capacitor electrode sheet is improved, and the energy density of the capacitor is increased. On the one hand, the bonding between the conductive adhesive layer and the electrode active material layer is firm, which not only reduces the impedance of the capacitor electrode sheet, but also improves the flexibility of the capacitor electrode sheet, ensuring the structural integrity of the capacitor electrode sheet under a certain degree of bending and twisting, the structural stability and safety of the capacitor electrode sheet, reducing the probability of powder falling and cracking of the electrode active coating, thereby improving the cycle performance of the capacitor and extending the service life. On the other hand, by utilizing the viscosity of the conductive adhesive layer in the capacitor electrode sheet, the connection between the capacitor electrode sheet and the capacitor housing can be realized, abandoning the traditional welding method, simplifying the electrode sheet preparation process, and improving the flexible characteristics 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 housing, and at the same time, due to the good conductivity of the conductive adhesive layer, it can play a current collecting role.

[0007] In addition, it should be noted that when the electrode sheet includes a conductive adhesive layer, a current collector, and an electrode active material layer arranged in sequence, although the conductive adhesive layer can also bond the electrode sheet to other capacitor components, when the capacitor is subjected to external impact or drop, the pulling force exerted by the capacitor housing on the conductive adhesive layer is greater than the pulling force exerted by the current collector on the double-sided tape. The difference between the above pulling forces easily causes the side of the conductive adhesive layer adhered to the current collector to have edge collapse and tearing, resulting in burrs on the current collector. The burrs are prone to tip discharge with the capacitor metal housing, causing capacitor short circuit. However, the capacitor electrode sheet provided by this solution does not use a current collector. Even if the side of the conductive layer adhered to the electrode active material layer has edge collapse and tearing due to the difference in pulling forces, the electrode active material layer is not likely to generate burrs, and there will be no short circuit caused by burrs. Therefore, the capacitor electrode sheet provided by this solution also improves the safety and anti-drop effect of the capacitor using it.

[0008] Preferably, the capacitor electrode sheet is composed of an electrode active material layer and a conductive adhesive layer compounded with the electrode active material layer.

[0009] Preferably, the conductive adhesive layer is disposed on at least one side of the electrode active material layer.

[0010] Preferably, 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 to 4; 96 to 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 carrier transport efficiency can be increased, and thus the fast charging performance of the capacitor electrode sheet can be improved. At the same time, it can ensure that the conductive adhesive layer can still maintain excellent viscosity and structural stability even when immersed in the electrolyte for a long time, can play a reliable fixing role for the capacitor electrode sheet applied thereto, and will not dissolve by-products that affect the normal operation of the battery.

[0011] Preferably, the conductive agent comprises at least one of conductive carbon black, carbon nanotubes, graphene, and carbon fibers.

[0012] Preferably, the binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0013] Preferably, in the conductive adhesive layer, the specific surface area of the conductive agent is 40 to 100 m 2 / g, and the median particle size D 50 of the conductive agent is 10 to 100 nm. The conductive adhesive layer prepared by using a conductive agent that meets the above requirements has good conductivity and can achieve a low resistance value. By controlling 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, meeting the extremely strict conductive requirements of the capacitor for conductivity, and enabling the conductive agent to bond and combine in the conductive adhesive layer, so that the conductive agent will not easily fall off from the surface of the conductive adhesive layer.

[0014] Preferably, the thickness of the conductive adhesive layer is 10 to 100 μm. By adjusting the thickness of the conductive adhesive layer, the bonding effect 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 enhanced, and the specific energy of the capacitor electrode sheet can be increased to achieve lightweight.

[0015] Preferably, 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.

[0016] Preferably, the lithium-containing oxide negative electrode material comprises at least one of lithium titanate, lithium vanadate, and lithium titanium silicate.

[0017] Preferably, the carbon-based negative electrode material comprises at least one of graphite, mesocarbon microbeads, soft carbon, hard carbon, and graphene.

[0018] Preferably, the silicon-based negative electrode material comprises at least one of silicon, silicon oxide, and silicon / carbon composite materials.

[0019] Preferably, 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 / g. By adding a porous carbon electrode material with a high specific surface area to the negative electrode sheet of the capacitor to form a double-layer structure, it is beneficial to improve the energy density of the capacitor.

[0020] Preferably, the porous carbon electrode material comprises porous activated carbon and / or biomass carbon.

[0021] Preferably, the median particle size D of the porous carbon electrode material 50 is 3-10 μm.

[0022] Preferably, in the electrode active material layer, the mass fraction of the negative electrode active material is 60-98%.

[0023] Preferably, in the electrode active material layer, the mass fraction of the carbon electrode material is 2-20%.

[0024] Preferably, in the electrode active material layer, the mass fraction of the negative electrode conductive agent is 1-8%.

[0025] Preferably, in the electrode active material layer, the mass fraction of the negative electrode binder is 1-8%.

[0026] Preferably, 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.

[0027] Preferably, the lithium-containing compound comprises at least one of a layered transition metal oxide, a polyanion compound, and a spinel compound.

[0028] Preferably, when the capacitor electrode sheet is a negative electrode, the thickness of the electrode active material layer is 200-2000 μm.

[0029] Preferably, when the capacitor electrode sheet is a positive electrode, the thickness of the electrode active material layer is 100-1000 μm.

[0030] According to another aspect of the present invention, there is provided a method for preparing the above-mentioned capacitor electrode sheet, comprising the following operations: mixing a binder, a conductive agent and a solvent to obtain a conductive rubber material, coating the conductive rubber material on the surface of the electrode active material layer, curing and rolling to obtain the capacitor electrode sheet.

[0031] Preferably, when the thickness of the electrode active material layer > 200 μm, a dry method is used for preparation.

[0032] Preferably, the dry method includes the following operations: mixing the raw materials for preparing the electrode active material layer in proportion to obtain a dry powder of the electrode material; and then forming the electrode active material layer with the required thickness by heating and extrusion of the dry powder of the electrode material.

[0033] Preferably, when the thickness of the electrode active material layer ≤ 200 μm, the wet method is used for preparation.

[0034] Preferably, the wet method includes the following operations: mixing the positive electrode binder or the negative electrode binder with the solvent in proportion to obtain an electrode adhesive solution, then mixing the remaining raw materials for preparing the electrode active material layer with the electrode adhesive solution to obtain a wet slurry, and finally coating the wet slurry on a flat surface and subjecting it to baking treatment to obtain the electrode active material layer.

[0035] According to another aspect of the present invention, a capacitor is provided, which includes the above capacitor electrode sheet, or includes a capacitor electrode sheet prepared by the above preparation method. The interlayer structure of the electrode sheet of the above capacitor is simple and has a small thickness, which can effectively improve the energy density of the capacitor, reduce the possibility of self-discharge of the capacitor, extend the endurance, and at the same time has high reliability and safety, is easy to disassemble, is conducive to batch production, realizes miniaturization and ultra-thinness, so as to adapt to ultra-thin terminal products.

[0036] Preferably, the capacitor includes a housing and a cover that are insulated and connected. The housing and the cover form a receiving cavity. Inside the receiving cavity, a positive electrode sheet, a separator, and a negative electrode sheet are sequentially stacked. At least part of the positive electrode sheet is connected to the housing, and at least part of the negative electrode sheet is connected to the cover. The positive electrode sheet and / or the negative electrode sheet includes a capacitor electrode sheet, and the conductive adhesive layer of the capacitor electrode sheet faces away from the separator. Compared with the traditional multi-layer laminated or wound electrode sheets, the above capacitor uses single-piece positive and negative electrode sheets respectively, which can greatly improve the energy density of the capacitor, and at the same time has a simple production process, high production efficiency, is conducive to batch production, and is suitable for ultra-thin products.

[0037] Preferably, the negative electrode sheet is a capacitor electrode sheet, and the conductive adhesive layer of the capacitor electrode sheet is connected to the cover.

[0038] Preferably, the positive electrode sheet is a capacitor electrode sheet, and the conductive adhesive layer of the capacitor electrode sheet is connected to the housing.

[0039] Preferably, the receiving cavity is also filled with an electrolyte.

[0040] Preferably, the housing is connected to the cover through an insulating component.

[0041] Preferably, the housing is snap-connected to the cover through an insulating component.

[0042] Preferably, the insulating component is arranged inside the housing, and the cover is snap-connected to the insulating component.

[0043] Preferably, the insulating component is an insulating rubber ring.

[0044] Preferably, the separator includes a polymer separator, a non-woven separator or a glass fiber separator.

[0045] Preferably, the housing is made of stainless steel.

[0046] Preferably, the cover is made of stainless steel.

[0047] Preferably, the insulating component is made of at least one of polypropylene, polyphenylene sulfide or polyether ether ketone.

[0048] Preferably, the electrolyte includes an organic solvent and a lithium salt.

[0049] Preferably, the organic solvent includes a carbonate solvent and / or an ether solvent.

[0050] Preferably, the lithium salt includes at least one of LiPF6, LiTFSI, LiFSI, LiBOB or LiBF4.

[0051] Preferably, the area ratio of the conductive adhesive layer to the electrode active material layer is 0.95 - 1.05:0.95 - 1.05.

[0052] Preferably, the area ratio of the conductive adhesive layer to the electrode active material layer is 1:1.

[0053] Preferably, 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.

[0054] Preferably, the capacitor electrode sheet is circular, and the diameter ratio of the conductive adhesive layer to the electrode active material layer is 1:1.

[0055] Preferably, the diameter of the capacitor is 10 - 24 mm.

[0056] Preferably, the thickness of the capacitor is 1.6 - 5 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Schematic diagram of the structure of the negative electrode sheet provided for Experimental Group 1A;

[0058] Figure 2 Schematic diagram of the structure of the positive electrode sheet provided for Experimental Group 1A;

[0059] Figure 3 Schematic diagram of the structure of the capacitor provided for Experimental Group 1A;

[0060] The corresponding relationships of the above-mentioned reference numerals are as follows: 1. positive electrode active material layer, 2. negative electrode active material layer, 3. separator, 4. insulating rubber ring, 5. cover body, 6. housing, 7. positive electrode conductive adhesive layer, 8. negative electrode conductive adhesive layer. Detailed implementation manners

[0061] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the accompanying drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0062] Embodiment 1

[0063] Experimental group 1A

[0064] This experimental group provides a capacitor, which includes a positive electrode sheet, a negative electrode sheet, a separator 3, an insulating rubber ring 4, a housing 6, and a cover body 5. Among them, both the positive electrode sheet and the negative electrode sheet adopt capacitor electrode sheets.

[0065] 1. Negative electrode sheet

[0066] As Figure 1 shown, the negative electrode sheet is composed of a negative electrode active material layer 2 and a negative electrode conductive adhesive layer 8 compounded with the negative electrode active material layer 2. The raw material composition of the negative electrode sheet is shown in the following table. Among them, the thickness of the negative electrode active material layer 2 is 1500 μm, the thickness of the negative electrode conductive adhesive layer 8 is 50 μm, the negative electrode sheet is circular, the diameter ratio of the negative electrode conductive adhesive layer 8 to the negative electrode active material layer 2 is 1:1, and the area ratio of the negative electrode active material layer 2 to the negative electrode conductive adhesive layer 8 is 1:1.

[0067] Table 1. Raw material composition of the negative electrode active material layer 2 and the negative electrode conductive adhesive layer 8

[0068]

[0069] Among them, in the raw materials for preparing the negative electrode active material layer 2, the lithium-containing oxide adopts 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 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 materials for preparing the negative electrode 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 50In the range of 10 to 30 nm.

[0070] The preparation method of the negative electrode sheet includes the following operations:

[0071] Prepare the negative electrode active material layer 2: Mix the raw materials for preparing the negative electrode active material layer 2 in proportion to obtain a dry powder of the negative electrode material, and then form the negative electrode active material layer 2 with the required thickness by heating and extrusion.

[0072] Prepare the negative electrode conductive adhesive layer 8: Mix the binder, conductive agent and solvent to obtain a conductive adhesive material, coat the conductive adhesive material on the surface of the negative electrode active material layer 2, cure and roll to obtain the negative electrode sheet.

[0073] 2. Positive electrode sheet

[0074] As Figure 2 shown, 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 sheet is shown in the following table. Among them, 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.

[0075] Table 2. Raw material composition of the positive electrode active material layer 1 and the positive electrode conductive adhesive layer 7

[0076]

[0077] Among them, in the raw materials 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 to 60 m 2 / g, and the median particle size D 50 is in the range of 80 to 90 nm. In the raw materials for preparing the positive electrode conductive adhesive layer 7, the specific surface area of the conductive carbon black is in the range of 70 to 90 m 2 / g, and the median particle size D 50 is in the range of 10 to 30 nm.

[0078] The preparation method of the positive electrode sheet includes the following operations:

[0079] Prepare the positive electrode active material layer 1: Mix the raw materials for preparing the positive electrode active material layer 1 in proportion to obtain a dry powder of the positive electrode material, and then form the positive electrode active material layer 1 with the required thickness by heating and extrusion.

[0080] Prepare the positive electrode conductive adhesive layer 7: Mix the binder, conductive agent and solvent to obtain a conductive adhesive material, coat the conductive adhesive material on the surface of the positive electrode active material layer 1, cure and roll to obtain the positive electrode sheet.

[0081] 3. Capacitor

[0082] As shown Figure 3 in the figure, a housing 6 and a cover 5 form a receiving cavity. An anode plate, a separator 3 and a cathode plate are sequentially stacked in the receiving cavity, with the separator 3 positioned between the anode plate and the cathode plate; the cover 5 and the housing 6 are separated by an insulating rubber ring 4; the positive conductive adhesive layer 7 of the anode plate faces away from the separator, and at least a part of the positive conductive adhesive layer 7 of the anode plate is connected to the housing 6. The negative conductive adhesive layer 8 of the cathode plate faces away from the separator, and at least a part of the negative conductive adhesive layer 8 of the cathode plate is connected to the cover 5. The insulating rubber ring 4 is arranged inside the housing 6, and the cover 5 is snap-connected to the insulating rubber ring 4.

[0083] Among them, the housing 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 receiving cavity is also filled with an electrolyte, and the electrolyte includes LiPF6, EC, DMC and EMC.

[0084] The size specification of the capacitor provided in this embodiment is 1016 (diameter: 10 mm, thickness: 1.6 mm). In other embodiments, the size specifications of the capacitor include but are not limited to 1016 (diameter: 10 mm, thickness: 1.6 mm), 1216 (diameter: 12 mm, thickness: 1.6 mm), 2016 (diameter: 20 mm, thickness: 1.6 mm), 2032 (diameter: 20 mm, thickness: 3.2 mm) and 2450 (diameter: 24 mm, thickness: 5 mm).

[0085] Comparison Group 1A

[0086] This comparison group refers to the preparation method provided by Experimental Group 1A to prepare a capacitor. The difference between this comparison group and Experimental Group 1A is that: an aluminum foil with a thickness of 180 μm is used to replace the negative conductive adhesive layer 8 in Experimental Group 1A, and an aluminum foil with a thickness of 180 μm is used to replace the positive conductive adhesive layer 7 in Experimental Group 1A. At the same time, during the preparation of the capacitor, a welding method is used to connect the aluminum foil in the negative electrode to the cover 5, and the aluminum foil in the positive electrode to the housing 6. The remaining raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0087] Comparison Group 2A

[0088] This comparative group prepared a capacitor with reference to the preparation method provided by experimental group 1A. The differences between this comparative group and experimental group 1A are as follows: The negative electrode sheet includes a negative electrode conductive adhesive layer 8, a negative electrode current collector, and a negative electrode active material layer 2 arranged in sequence. The negative electrode current collector uses aluminum foil with a thickness of 180 μm; the positive electrode sheet includes a positive electrode conductive adhesive layer 7, a positive electrode current collector, and a positive electrode active material layer 1 arranged in sequence. The positive electrode current collector uses aluminum foil with a thickness of 180 μm. The other raw material ratios and preparation methods are strictly the same as those of experimental group 1A, 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 those of experimental group 1A.

[0089] Comparative group 3A

[0090] This comparative group prepared a capacitor with reference to the preparation method provided by experimental group 1A. The differences between this comparative group and experimental group 1A are as follows: The aluminized film current collector with a thickness of 10 μm is used to replace the negative electrode conductive adhesive layer 8 in experimental group 1A, and the aluminized film current collector with a thickness of 10 μm is used to replace the positive electrode conductive adhesive layer 7 in experimental group 1A. At the same time, during the process of preparing the capacitor, the aluminized film current collector in the negative electrode is connected to the cover body 5 by welding, and the aluminized film current collector in the positive electrode is connected to the housing 6 by welding. The other raw material ratios and preparation methods are strictly the same as those of experimental group 1A.

[0091] Test example 1

[0092] Test objects: The capacitors provided by each experimental group and comparative group in Example 1.

[0093] Test items and test methods:

[0094] (1) Capacitance test: The constant current discharge method is adopted. The capacitance deviation should not be less than 80% and not exceed 180% of the rated capacitance, that is, the discharge capacitance should be between 0.352 and 0.792 F. The larger the value within the range of the discharge capacitance, the better the electrical performance of the capacitor; The capacitor is connected to a DC circuit with a constant current / constant voltage source. After the constant current / constant voltage source reaches the rated voltage UR, it is charged at a constant voltage for 30 min, and then the capacitor is connected to a circuit with a constant current discharge device and discharged at a constant current I (I = 0.1 ± 0.03C). The voltage across the capacitor is measured. Timing starts at t1 when U1 = 0.8UR and stops at t2 when U2 = 0.4UR. The discharge capacitance value is calculated using the formula C = I(t2 - t1) / U1 - U2.

[0095] (2) ESR test: The alternating current test is adopted and measured using an internal resistance tester. The smaller the ESR, the better the electrical performance of the capacitor.

[0096] Test results: As shown in the following table.

[0097] Table 3. Test data measured in this test case and the structures of each test object

[0098]

[0099]

[0100] Result analysis:

[0101] By comparing the performance of the capacitors provided by experimental group 1A with those of control groups 1A - 3A, it can be found that when the capacitor electrode sheet includes an electrode active material layer and a conductive adhesive layer composite with the electrode active material layer, the capacitor simultaneously has a large capacitance and a low ESR impedance, that is, the capacitor has excellent energy density and electrochemical performance.

[0102] Among them, by comparing the capacitors provided by experimental group 1A with those of control groups 1A and 3A, it can be found that during the preparation of the capacitor in experimental group 1A, the traditional welding process was abandoned, reducing the possibility of stress concentration between the current collector and the capacitor housing, resulting in the emergence of structural weak points, which is reflected in the smaller ESR impedance of the capacitor in experimental group 1A.

[0103] By comparing the capacitors provided by experimental group 1A with those of control group 2A, it can be found that in the capacitors provided by control group 2A, the electrode sheet contains both a metal current collector and a conductive adhesive layer, and there are dissimilar material contact surfaces between the electrode active material layer and the metal current collector, as well as between the metal current collector and the conductive adhesive layer, that is, there are at least 2 layers of dissimilar material contact surfaces. While in the capacitors provided by experimental group 1A, the electrode sheet only has 1 layer of dissimilar material contact surface, which is reflected in the smaller ESR impedance of the capacitor in experimental group 1A. At the same time, in the actual test results, it is found that the capacitors provided by experimental group 1A show excellent safety and anti - drop performance in the 1.8m drop test. The capacitors in experimental group 1A still have good structural stability and electrochemical performance after the drop test and are not prone to capacitor short - circuit, while the capacitors provided by control group 2A have uneven electric field distribution and local overheating after the drop test.

[0104] Example 2

[0105] Experimental group 1B

[0106] This experimental group refers to the preparation method provided by experimental group 1A to prepare a capacitor. The difference between this experimental group and experimental group 1A is that during the preparation of 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 other raw material ratios and preparation methods are strictly the same as those of experimental group 1A.

[0107] Experimental Group 2B

[0108] This experimental group refers to the preparation method provided by Experimental Group 1A to prepare a capacitor. The difference between this experimental group and Experimental Group 1A is that during the preparation of 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 other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0109] Experimental Group 3B

[0110] This experimental group refers to the preparation method provided by Experimental Group 1A to prepare a capacitor. The difference between this experimental group and Experimental Group 1A is that during the preparation of 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 4:96. The other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0111] Experimental Group 4B

[0112] This experimental group refers to the preparation method provided by Experimental Group 1A to prepare a capacitor. The difference between this experimental group and Experimental Group 1A is that during the preparation of 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 5:95. The other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0113] Test Example 2

[0114] Test objects: The capacitors provided by Experimental Group 1A and each experimental group in Example 2.

[0115] Test items and test methods:

[0116] (1) Capacitance test: Exactly the same as Test Example 1.

[0117] (2) ESR test: Exactly the same as Test Example 1.

[0118] Test results: As shown in the following table:

[0119] Table 4. Test data measured in this test example and the ratios of each test object

[0120]

[0121]

[0122] Result analysis:

[0123] Comparing the capacitors provided by Experimental Group 1C to 4C with those of Experimental Group 1A, it can be found that as the content of the conductive agent in the conductive adhesive layer decreases, the capacitance of the capacitor first increases and then decreases, and the ESR impedance of the capacitor first decreases and then increases. When the mass ratio of the binder to the conductive agent in the conductive adhesive layer is 0.5 - 4:96 - 99.5, the capacitor simultaneously has a relatively large capacitance and a low ESR impedance.

[0124] Example 3

[0125] Experimental Group 1C

[0126] This experimental group prepared a capacitor with reference to the preparation method provided by Experimental Group 1A. The difference between this experimental group and Experimental Group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 was adjusted to 10 μm. The other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0127] Experimental Group 2C

[0128] This experimental group prepared a capacitor with reference to the preparation method provided by Experimental Group 1A. The difference between this experimental group and Experimental Group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 was adjusted to 30 μm. The other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0129] Experimental Group 3C

[0130] This experimental group prepared a capacitor with reference to the preparation method provided by Experimental Group 1A. The difference between this experimental group and Experimental Group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 was adjusted to 70 μm. The other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0131] Experimental Group 4C

[0132] This experimental group prepared a capacitor with reference to the preparation method provided by Experimental Group 1A. The difference between this experimental group and Experimental Group 1A is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 was adjusted to 100 μm. The other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0133] Experimental Group 5C

[0134] This experimental group prepared a capacitor with reference to the preparation method provided by Experimental Group 1A. The difference between this experimental group and Experimental Group 1A is that during the preparation of the negative electrode active material layer 2, an equal mass of negative conductive agent was used to replace the porous carbon electrode material in Experimental Group 1A. The other raw material ratios and preparation methods are strictly the same as those of Experimental Group 1A.

[0135] Test Example 3

[0136] Test subjects: The capacitors provided by experimental group 1A and each experimental group in Example 3.

[0137] Test items and test methods:

[0138] (1) Capacitance test: Exactly the same as Test Example 1.

[0139] (2) ESR test: Exactly the same as Test Example 1.

[0140] Test results: As shown in the following table:

[0141] Table 4. Test data measured in this test example and variable parameters of each test subject

[0142]

[0143] Result analysis:

[0144] By comparing the capacitors provided by experimental groups 1C - 4C with those provided by experimental group 1A, it can be found that as the thickness of the conductive adhesive layer increases, the capacitance of the capacitor shows a trend of first increasing and then decreasing, and the ESR impedance of the capacitor shows a trend of first decreasing and then increasing. Among them, the impedance of the capacitor in experimental group 1A is the smallest, only 1.52 Ω.

[0145] By comparing the capacitors provided by experimental group 1A with those provided by experimental group 5C, it can be found that when a porous carbon electrode material is used in the negative electrode active coating, the energy density of the capacitor is higher, the capacitance of the capacitor is larger, and the ESR impedance is smaller.

[0146] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A capacitor electrode sheet, characterized in that: It comprises an electrode active material layer and a conductive adhesive layer compounded with the electrode active material layer.

2. The capacitor electrode sheet according to claim 1, characterized in that: The conductive adhesive layer includes 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 according to claim 2, characterized in that: In the conductive adhesive layer, the specific surface area of ​​the conductive agent is 40 to 100 m 2 / g, the median particle size D of the conductive agent 50 It is 10 to 100 nm.

4. The capacitor electrode sheet according to claim 1, characterized in that: The thickness of the conductive adhesive layer is 10-100 μm.

5. The capacitor electrode sheet according to claim 1, characterized in that: The electrode active material layer includes a negative electrode active material, a negative electrode conductor and a negative electrode binder. The negative electrode active material includes at least one of a lithium oxide-containing negative electrode material, a carbon-based negative electrode material and a silicon-based negative electrode material.

6. The capacitor electrode sheet according to claim 5, characterized in that: The electrode active material layer also includes a porous carbon electrode material, and the specific surface area of ​​the porous carbon electrode material is 1400 to 2000 m 2 / g.

7. The capacitor electrode sheet according to claim 1, characterized in that: The electrode active material layer includes a positive electrode active material, a positive electrode conductor and a positive electrode binder, and the positive electrode active material includes a lithium-containing compound.

8. A method for preparing a capacitor electrode sheet according to any one of claims 1 to 7, characterized in that: The following operations are included: The binder, the conductive agent and the solvent are mixed to prepare a conductive rubber material, and the conductive rubber material is coated on the surface of the electrode active material layer, solidified and rolled to obtain the capacitor electrode sheet.

9. A capacitor, characterized in that: The capacitor comprises the capacitor electrode sheet as claimed in any one of claims 1 to 7, or comprises a capacitor electrode sheet prepared by the preparation method as claimed in claim 8.

10. The capacitor according to claim 9, characterized in that: It comprises a shell and a cover body which are insulated and connected, the shell and the cover body form a receiving cavity, the positive electrode sheet, the diaphragm and the negative electrode sheet are sequentially stacked in the receiving cavity, 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 body; 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 with its back to the diaphragm.

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