Capacitor electrode plate and capacitor using same

Abstract

The utility model provides a capacitor electrode plate and a capacitor using the same. 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] This utility model belongs to the field of capacitors, and relates to a capacitor electrode sheet and a capacitor using the same. Background Technology

[0002] Supercapacitors, also known as electric double-layer capacitors, electrochemical capacitors, gold capacitors, or farad capacitors, are a new type of energy storage device that falls between traditional capacitors and batteries. A supercapacitor can be viewed as two non-reactive electrode plates suspended in an electrolyte. When a voltage is applied to the plates, the positive plate attracts negative ions from the electrolyte, and the negative plate attracts positive ions, effectively forming two capacitive storage layers. The separated positive ions are near the negative plate, and the negative ions are near the positive plate. Therefore, supercapacitors are a novel energy storage material, standing out due to their long cycle life, high power density, and wide operating temperature range. The performance of a supercapacitor depends heavily on the composition of the electrode materials and the design of the electrode structure.

[0003] To improve the structural stability of the components in a capacitor and prevent relative displacement between the electrodes and the capacitor casing during operation, the electrodes are typically welded to the casing. However, in practice, unsatisfactory welding results often occur, such as solder joint perforation and excessively high solder joint protrusions. This seriously hinders the further development and application of capacitors. On the one hand, solder joint perforation reduces the weld connection strength and conductivity, affecting the normal operation of the capacitor; on the other hand, excessively high solder joint protrusions increase the risk of the diaphragm being punctured, threatening the safety performance of the capacitor. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a capacitor electrode sheet and a capacitor using the same, wherein the capacitor electrode sheet has good conductivity and mechanical properties, and can improve the energy density and cycle stability of the capacitor using the same.

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

[0006] The capacitor electrode sheet provided by this utility model includes a conductive adhesive layer and an electrode active material layer. 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 one hand, the strong adhesion between the conductive adhesive layer and the electrode active material layer not only reduces the impedance of the capacitor electrode sheet but also improves its flexibility. This ensures that the capacitor electrode sheet maintains structural integrity under a certain degree of bending and twisting, enhancing its structural stability and safety. It also reduces the probability of powdering and cracking of the electrode active coating, thereby improving the cycle performance of the capacitor and extending its service life. On the other hand, the adhesiveness of the conductive adhesive layer in the capacitor electrode sheet allows for connection between the capacitor electrode sheet and the capacitor casing, eliminating the need for traditional welding methods, simplifying the electrode sheet manufacturing process, and improving the flexibility and high energy density of the capacitor electrode sheet. Furthermore, the conductive adhesive layer ensures sufficient contact between the active material layer and the structural housing, and its good conductivity also enables it to act as a current collector.

[0007] Furthermore, it should be noted that when the electrode sheet includes a conductive adhesive layer, a current collector, and an electrode active material layer arranged sequentially, although the conductive adhesive layer can still bond the electrode sheet to other capacitor elements, when the capacitor is subjected to external impact or drop, the tensile force exerted by the capacitor casing on the conductive adhesive layer is greater than the tensile force exerted by the current collector on the double-sided tape. This difference in tensile force can easily cause the conductive adhesive layer to chip or tear on the side bonded to the current collector, resulting in burrs on the current collector. These burrs can easily cause point discharge with the capacitor's metal casing, causing a short circuit. However, the capacitor electrode sheet provided in this solution does not use a current collector. Even if the conductive layer chip or tear on the side bonded to the electrode active material layer due to the difference in tensile force, the electrode active material layer is less likely to develop burrs, and short circuits will not occur due to burrs. Therefore, the capacitor electrode sheet provided in this solution also improves the safety and drop resistance of the capacitors using it.

[0008] Preferably, the capacitor electrode sheet is composed of an electrode active material layer and a conductive adhesive layer composite 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 thickness ratio of the conductive adhesive layer to the electrode active material layer is 1:10 to 30.

[0011] Preferably, 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, and the electrolyte resistance of the conductive adhesive layer can be improved, thereby enhancing the structural stability of the capacitor. Furthermore, the specific energy of the capacitor electrode sheets can be increased, achieving weight reduction.

[0012] Preferably, the thickness of the electrode active material layer is 100–2000 μm.

[0013] Preferably, when the capacitor electrode sheet is the negative electrode, the thickness of the electrode active material layer is 200–2000 μm.

[0014] Preferably, when the capacitor electrode sheet is the positive electrode, the thickness of the electrode active material layer is 100–1000 μm.

[0015] Preferably, the area ratio of the conductive adhesive layer to the electrode active material layer is 0.95–1.05:0.95–1.05.

[0016] Preferably, the area ratio of the conductive adhesive layer to the electrode active material layer is 1:1.

[0017] 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.

[0018] 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.

[0019] According to another aspect of this utility model, a capacitor is provided, which includes the aforementioned capacitor electrode sheets. The capacitor has a simple interlayer structure and small thickness between the electrode sheets, which can effectively improve the energy density of the capacitor, reduce the possibility of self-discharge, extend the battery life, and at the same time have high reliability and safety, are easy to disassemble, are conducive to mass production, and achieve miniaturization and ultra-thinness to adapt to ultra-thin terminal products.

[0020] Preferably, the capacitor includes an insulated housing and a cover, which form a receiving cavity. A positive electrode, a separator, and a negative electrode are sequentially stacked within the cavity. The positive electrode is at least partially connected to the housing, and the negative electrode is at least partially connected to the cover. The positive and / or negative electrode includes capacitor electrode sheets, with the conductive adhesive layer of the capacitor electrode sheets facing away from the separator. Compared to traditional multi-layered or wound electrode sheets, the above capacitor uses single positive and negative electrode sheets, which can significantly improve the energy density of the capacitor. Furthermore, the manufacturing process is simple and efficient, facilitating mass production and adapting to ultra-thin products.

[0021] Preferably, the negative electrode is a capacitor electrode, and the conductive adhesive layer of the capacitor electrode is connected to the cover; and / or, the positive electrode is a capacitor electrode, and the conductive adhesive layer of the capacitor electrode is connected to the housing.

[0022] Preferably, the cavity is also filled with electrolyte.

[0023] Preferably, the housing is connected to the cover via an insulating component.

[0024] Preferably, the housing is fastened to the cover by an insulating component.

[0025] Preferably, the insulating component is disposed inside the housing, and the cover is fastened to the insulating component.

[0026] Preferably, the insulating component is an insulating rubber ring.

[0027] Preferably, the diaphragm includes a polymer diaphragm, a nonwoven fabric diaphragm, or a glass fiber diaphragm.

[0028] Preferably, the shell is made of stainless steel.

[0029] Preferably, the cover is made of stainless steel.

[0030] Preferably, the insulating component is made of any one of polypropylene, polyphenylene sulfide, or polyetheretherketone.

[0031] Preferably, the diameter of the capacitor is 10 to 24 mm.

[0032] Preferably, the thickness of the capacitor is 1.6 to 5 mm. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the negative electrode sheet provided in Example 1;

[0034] Figure 2 This is a schematic diagram of the positive electrode sheet provided in Example 1;

[0035] Figure 3 This is a schematic diagram of the capacitor provided in Example 1;

[0036] The correspondence of the reference numerals in the above figures is as follows: 1. Positive electrode active material layer, 2. Negative electrode active material layer, 3. Separator, 4. Insulating ring, 5. Cover, 6. Shell, 7. Positive electrode conductive adhesive layer, 8. Negative electrode conductive adhesive layer. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of this utility model will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0038] Example 1

[0039] Experimental group 1

[0040] This experimental group provides a capacitor comprising a positive electrode, a negative electrode, a separator 3, an insulating ring 4, a housing 6, and a cover 5. Both the positive and negative electrodes are capacitor electrode plates.

[0041] 1. Negative electrode plate

[0042] like Figure 1 As shown, the negative electrode sheet consists of a negative electrode active material layer 2 and a negative electrode conductive adhesive layer 8 composite with the negative electrode active material layer 2. 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.

[0043] 2. Positive electrode plate

[0044] like Figure 2 As shown, the positive electrode sheet consists of a positive electrode active material layer 1 and a positive electrode conductive adhesive layer 7 composite with the positive electrode active material layer 1. The thickness of the positive electrode active material layer 1 is 500 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.

[0045] 3. Capacitor

[0046] like Figure 3As shown, the shell 6 and the cover 5 form a receiving cavity, in which a positive electrode, a separator 3, and a negative electrode are stacked sequentially, with the separator 3 positioned between the positive and negative electrode. The cover 5 and the shell 6 are separated by an insulating rubber ring 4. The positive conductive adhesive layer 7 of the positive electrode faces away from the separator and is at least partially connected to the shell 6. The negative conductive adhesive layer 8 of the negative electrode faces away from the separator and is at least partially connected to the cover 5. Specifically, by utilizing the adhesiveness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8, the connection between the positive electrode and the shell 6, and between the negative electrode and the cover 5, can be achieved, eliminating the traditional welding method, simplifying the electrode preparation process, and improving the flexibility and high energy density of the capacitor electrode.

[0047] The housing 6 is made of stainless steel, the cover 5 is made of stainless steel, and the insulating ring 4 is made of polypropylene. The insulating ring 4 is located inside the housing 6, and the cover 5 is fastened to the insulating ring 4. The cavity is also filled with electrolyte. Specifically, the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 can still maintain excellent adhesion even when immersed in the electrolyte.

[0048] The capacitor provided in this embodiment has a size specification of 1016 (diameter 10mm, thickness 1.6mm). In other embodiments, the capacitor size specifications include, but are not limited to, 1016 (diameter 10mm, thickness 1.6mm), 1216 (diameter 12mm, thickness 1.6mm), 2016 (diameter 20mm, thickness 1.6mm), 2032 (diameter 20mm, thickness 3.2mm), and 2450 (diameter 24mm, thickness 5mm).

[0049] Comparison Group 1

[0050] This comparative group prepared a capacitor using the same method as experimental group 1. The difference between this comparative group and experimental group 1 is that an aluminum foil with a thickness of 180 μm was used to replace the negative conductive adhesive layer 8 in experimental group 1, and an aluminum foil with a thickness of 180 μm was used to replace the positive conductive adhesive layer 7 in experimental group 1. The remaining raw material ratios and preparation methods were strictly consistent with those of experimental group 1.

[0051] Comparison Group 2

[0052] This comparative group prepared a capacitor using the same method as experimental group 1. The difference between this comparative group and experimental group 1 is that the negative electrode consists of a negative conductive adhesive layer 8, a negative current collector, and a negative active material layer 2 arranged sequentially, with the negative current collector being an aluminum foil with a thickness of 180 μm; the positive electrode consists of a positive conductive adhesive layer 7, a positive current collector, and a positive active material layer 1 arranged sequentially, with the positive current collector being an aluminum foil with a thickness of 180 μm. The remaining raw material ratios and preparation methods are strictly consistent with experimental group 1, especially the thickness and composition of the negative conductive adhesive layer 8, negative active material layer 2, positive conductive adhesive layer 7, and positive active material layer 1.

[0053] Comparison Group 3

[0054] This comparative group prepared a capacitor according to the preparation method provided in Experimental Group 1. The difference between this comparative group and Experimental Group 1 is that a 10μm thick aluminum-plated film current collector was used to replace the negative conductive adhesive layer 8 in Experimental Group 1, and a 10μm thick aluminum-plated film current collector was used to replace the positive conductive adhesive layer 7 in Experimental Group 1. The remaining raw material ratios and preparation methods were strictly consistent with those of Experimental Group 1.

[0055] Test Example 1

[0056] Test subjects: Capacitors provided by each experimental group and control group in Example 1.

[0057] Test items and test methods:

[0058] (1) Capacitance test: The constant current discharge method is adopted. The capacitance deviation should not be less than 80% and not more than 180% of the rated capacitance. That is, the discharge capacity should be between 0.352 and 792 F. The larger the value of the discharge capacity within the range, the better the electrical performance of the capacitor. Connect the capacitor to a DC circuit with a constant current / constant voltage source. After the constant current / constant voltage source reaches the rated voltage UR, charge it at a constant voltage for 30 minutes. Then connect the capacitor to a circuit with a constant current discharge device and discharge it with a constant current I (I = 0.1 ± 0.03 C). Measure the voltage across the capacitor. Start timing from U1 = 0.8UR as t1 and stop timing from U2 = 0.4UR as t2. Calculate the discharge capacity value using the formula C = I(t2 - t1) / U1 - U2.

[0059] (2) ESR test: AC current test is used, and internal resistance tester is used for measurement. The smaller the ESR, the better the electrical performance of the capacitor.

[0060] Test results are shown in the table below.

[0061] Table 1. Test data obtained in this test case and the structure of each test subject.

[0062] Group Electrode structure Capacity (F) ESR(Ω) Experimental group 1 Electrode active material layer + conductive adhesive layer 0.594 1.52 Comparison Group 1 Electrode active material layer + metal current collector 0.443 2.35 Comparison Group 2 Electrode active material layer + metal current collector + conductive adhesive layer 0.513 2.27 Comparison Group 3 Electrode active material layer + aluminum-coated current collector 0.354 3.61

[0063] Results analysis:

[0064] By comparing the performance of the capacitors provided in Experimental Group 1 with those in Control Groups 1-3, it can be found that when the capacitor includes a capacitor electrode sheet consisting of an electrode active material layer and a conductive adhesive layer composite with the electrode active material layer, the capacitor has both a large capacitance and a low ESR impedance, which means that the capacitor has excellent energy density and electrochemical performance.

[0065] Among them, comparing the capacitors provided by experimental group 1 with those provided by control group 1 and control group 3, it can be found that in the process of preparing the capacitor, experimental group 1 abandoned the traditional welding process, which reduced the stress concentration phenomenon between the current collector and the capacitor shell, thus reducing the possibility of structural weak points. This is reflected in the lower ESR impedance of the capacitor in experimental group 1.

[0066] Comparing the capacitors provided in Experimental Group 1 and Control Group 2, it can be observed that the capacitor in Control Group 2 uses an electrode sheet containing both a metal current collector and a conductive adhesive layer. This electrode sheet has at least two dissimilar material contact surfaces: one between the active electrode material layer and the metal current collector, and another between the metal current collector and the conductive adhesive layer. In contrast, the capacitor in Experimental Group 1 only has one dissimilar material contact surface, resulting in a lower ESR impedance. Furthermore, actual test results show that the capacitor in Experimental Group 1 exhibits excellent safety and drop resistance in a 1.8m drop test. The capacitor in Experimental Group 1 maintains good structural stability and electrochemical performance after the drop test, showing little tendency to short-circuit, while the capacitor in Control Group 2 exhibits uneven electric field distribution and localized overheating after the drop test.

[0067] Example 2

[0068] Experimental group 2

[0069] This experimental group prepared a capacitor according to the preparation method provided in Experimental Group 1. The difference between this experimental group and Experimental Group 1 is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 were adjusted to 10 μm. The remaining raw material ratios and preparation methods were strictly consistent with those of Experimental Group 1.

[0070] Experimental group 3

[0071] This experimental group prepared a capacitor according to the preparation method provided in Experimental Group 1. The difference between this experimental group and Experimental Group 1 is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 were adjusted to 30 μm. The remaining raw material ratios and preparation methods were strictly consistent with those of Experimental Group 1.

[0072] Experimental group 4

[0073] This experimental group prepared a capacitor according to the preparation method provided in Experimental Group 1. The difference between this experimental group and Experimental Group 1 is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 were adjusted to 70 μm. The remaining raw material ratios and preparation methods were strictly consistent with those of Experimental Group 1.

[0074] Experimental group 5

[0075] This experimental group prepared a capacitor according to the preparation method provided in Experimental Group 1. The difference between this experimental group and Experimental Group 1 is that the thickness of the positive conductive adhesive layer 7 and the negative conductive adhesive layer 8 were adjusted to 100 μm. The remaining raw material ratios and preparation methods were strictly consistent with those of Experimental Group 1.

[0076] Test Example 2

[0077] Test subjects: Capacitors provided in Experimental Group 1 and each experimental group in Example 2.

[0078] Test items and test methods:

[0079] (1) Capacity test: strictly consistent with test example 1.

[0080] (2) ESR test: strictly consistent with test example 1.

[0081] Test results are shown in the table below:

[0082] Table 2. Test data and variable parameters of each participant in this test case.

[0083] Group Conductive adhesive layer thickness Capacity (F) ESR(Ω) Experimental group 2 10μm 0.490 2.32 Experimental group 3 30μm 0.557 1.75 Experimental group 1 50μm 0.594 1.52 Experimental group 4 70μm 0.586 1.68 Experimental group 5 100μm 0.490 2.30

[0084] Results analysis:

[0085] Comparing the capacitors provided in experimental groups 1 to 5, 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, while the ESR impedance of the capacitor shows a trend of first decreasing and then increasing. Among them, the capacitor in experimental group 1 has the lowest impedance, only 1.52Ω.

[0086] The above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. A capacitor electrode sheet, characterized in that, The capacitor includes an electrode active material layer and a conductive adhesive layer composited with the electrode active material layer. No current collector is used in the capacitor electrode sheet. The conductive adhesive layer has good conductivity and can play the role of current collection.

2. The capacitor electrode sheet as described in claim 1, characterized in that, The thickness ratio of the conductive adhesive layer to the electrode active material layer is 1:10~30.

3. The capacitor electrode sheet as described in claim 1, characterized in that, The thickness of the conductive adhesive layer is 10~100μm.

4. The capacitor electrode sheet as described in claim 1, characterized in that, The thickness of the electrode active material layer is 100~2000μm.

5. A capacitor, characterized in that, The capacitor includes the capacitor electrode plates as described in any one of claims 1 to 4.

6. The capacitor as claimed in claim 5, characterized in that, The device includes an insulated housing and a cover, the housing and the cover forming a receiving cavity, in which a positive electrode, a separator and a negative electrode are sequentially stacked, the positive electrode being at least partially connected to the housing and the negative electrode being at least partially connected to the cover; the positive electrode and / or the negative electrode includes a capacitor electrode, and the conductive adhesive layer of the capacitor electrode is disposed opposite to the separator.

7. The capacitor as claimed in claim 6, characterized in that, The negative electrode is the capacitor electrode, and the conductive adhesive layer of the capacitor electrode is connected to the cover; and / or, the positive electrode is the capacitor electrode, and the conductive adhesive layer of the capacitor electrode is connected to the housing.

8. The capacitor as claimed in claim 6, characterized in that, The housing is connected to the cover via an insulating component.

9. The capacitor as claimed in claim 8, characterized in that, The insulating component is disposed inside the housing, and the cover is fastened to the insulating component.

10. The capacitor as claimed in claim 8, characterized in that, The insulating component is made of any one of polypropylene, polyphenylene sulfide, or polyetheretherketone.

Images