Composite pole piece and secondary battery

Abstract

The utility model belongs to the field of secondary batteries, and particularly relates to a composite pole piece and a secondary battery. The composite pole piece comprises a current collector and a safe priming coat arranged on at least one surface of the current collector, the active material layer is arranged on the outer surface of the safety priming coat; wherein the current collector is provided with an empty foil area, the empty foil area is provided with a tab, and at least one surface of the root part of the tab is provided with a first ceramic filling layer. Compared with the prior art, the first ceramic filling layer is arranged on at least one surface of the root part of the tab, so that better thickness flatness can be obtained, the overall consistency and stability of the battery assembly are ensured, and the key position of the positive tab group can be effectively protected. The measure can greatly reduce potential safety hazards such as internal short circuit caused by damage or deformation of the tab, so that the reliability and the safety of a battery product are improved.

Description

Technical Field

[0001] This utility model belongs to the field of secondary batteries, specifically relating to a composite electrode and a secondary battery. Background Technology

[0002] Traditional lithium batteries often fail to meet ideal safety standards when faced with stringent safety tests such as needle penetration and heavy object impact. This is especially true for stacked batteries, whose structural characteristics result in more significant safety hazards in the positive electrode area compared to wound batteries. In wound batteries, the positive electrode tabs can be effectively insulated by simply applying protective tape. However, stacked batteries have a much more complex structure, with numerous and widely distributed positive electrode tabs, making it impractical and uneconomical to apply protective tape to each one individually.

[0003] In today's market for small power products, such as handheld power tools and drones, the application of stacked batteries is increasing to meet the urgent need for high-power discharge. However, this also brings a thorny problem: while ensuring high performance, these products must also pass rigorous nail penetration and heavy object impact tests to guarantee user safety. However, due to the special characteristics of the positive electrode tab area of ​​stacked batteries, these products are highly susceptible to short circuits during testing or actual use, thus posing a safety hazard.

[0004] Therefore, given this situation, there is an urgent need to develop a new type of composite electrode to solve the aforementioned problems. Utility Model Content

[0005] One of the objectives of this invention is to provide a composite electrode to address the shortcomings of existing technologies. This composite electrode features a special design and optimization for the positive electrode tab area of ​​the stacked battery to reduce the risk of short circuits and ensure that the battery remains stable and safe even under extreme conditions such as puncture and impact from heavy objects.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A composite electrode includes: a current collector,

[0008] A safety primer coating is disposed on at least one surface of the current collector;

[0009] An active material layer is disposed on the outer surface of the safety primer layer;

[0010] The current collector has an empty foil area, the empty foil area is provided with a tab, and at least one surface at the root of the tab is provided with a first ceramic filling layer.

[0011] Preferably, the end of the active material layer has a thinning region, and the thinning region is provided with a second ceramic filling layer, so that the active material layer forms a flat surface.

[0012] Preferably, in the vertical cross-section of the thinned region, the sum of the thickness of the active material layer in the thinned region and the thickness of the second ceramic filler layer is equal to the thickness of the active material layer in the non-thinned region.

[0013] Preferably, the width of the second ceramic filler layer is a, and the width of the active material layer is c, where a and c satisfy the relationship: a / c = 0.003 to 0.6;

[0014] Preferably, the thickness of the second ceramic filler layer is b, and the thickness of the active material layer is d, where b and d satisfy the relationship: b / d = 0.005~0.5.

[0015] Preferably, the width of the first ceramic filler layer is A, and a and A satisfy the relationship: a / A = 0.8~1.2;

[0016] Preferably, the thickness of the first ceramic filler layer is B, and b and B satisfy the relationship: b / B = 0.8~1.2.

[0017] Preferably, A is 1-3 mm;

[0018] Preferably, a is 1 to 3 mm.

[0019] Preferably, B is 0.5–10 μm;

[0020] Preferably, b is 0.5 to 10 μm.

[0021] Preferably, the thickness ratio of the current collector, the safety primer, and the active material layer is 6–12:0.5–20:20–100.

[0022] Preferably, the thickness of the current collector is 6–12 μm;

[0023] Preferably, the thickness of the safety primer layer is 0.5–20 μm;

[0024] Preferably, the thickness of the active material layer is 20–100 μm.

[0025] The present invention also provides a secondary battery, comprising a positive electrode, a negative electrode and a separator, wherein the positive electrode is the composite electrode described above.

[0026] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0027] (1) By setting a first ceramic filler layer on at least one surface at the root of the tab, not only can a better thickness flatness be obtained, thereby ensuring the overall consistency and stability of the battery assembly, but also the critical position of the positive tab group can be effectively protected. This measure can greatly reduce potential safety hazards such as internal short circuits caused by damage or deformation of the tab, thereby improving the reliability and safety of the battery product.

[0028] (2) By applying a safety undercoating to the current collector, the safety performance of the battery can be significantly improved. This coating can reduce the reactivity during a short circuit, reduce the intensity of the reaction, and prevent runaway. At the same time, it can enhance the mechanical strength of the current collector, reduce the risk of short circuit, and ensure the stability and safety of the battery during long-term use. Attached Figure Description

[0029] The features, advantages, and technical effects of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0030] Figure 1 This is a schematic diagram of the structure of a composite electrode sheet according to an embodiment of the present invention.

[0031] The reference numerals in the attached figures are explained as follows:

[0032] 1. Current collector; 2. Safety primer layer; 3. Active material layer; 4. First ceramic filler layer; 5. Second ceramic filler layer; 6. Thinning zone. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] In the embodiments of this application, the same reference numerals denote the same parts, and for the sake of brevity, detailed descriptions of the same parts are omitted in different embodiments.

[0036] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail with reference to specific embodiments, but this is not intended to limit the present invention.

[0037] like Figure 1 As shown, this utility model provides a composite electrode, comprising: a current collector 1,

[0038] A safety primer layer 2 is disposed on at least one surface of the current collector 1;

[0039] The active material layer 3 is disposed on the outer surface of the safety primer layer 2;

[0040] The current collector 1 has an empty foil area, and the empty foil area is provided with a tab. At least one surface at the root of the tab is provided with a first ceramic filling layer 4.

[0041] By setting a first ceramic filler layer 4 on at least one surface at the root of the tab, not only can better thickness flatness be achieved, thus ensuring the overall consistency and stability of the battery assembly, but it can also effectively protect the critical position of the positive tab group. This measure can greatly reduce potential safety hazards such as internal short circuits caused by tab damage or deformation, thereby improving the reliability and safety of battery products.

[0042] The slurry formulation of the safety primer 2 is a low-conductivity material (one of LFP, LMFP, or ceramic), binder, and dispersant, applied to at least one surface of the current collector 1 in a ratio of 90-96:2-5:0.5-2 to form the safety primer 2.

[0043] By applying a safety undercoat to the current collector, the safety performance of the battery can be significantly improved. This coating reduces the reactivity and intensity of the reaction during a short circuit, preventing runaway, while also enhancing the mechanical strength of the current collector, reducing the risk of short circuits, and ensuring the stability and safety of the battery during long-term use.

[0044] The slurry formulation for the first ceramic filler layer 4 and the second ceramic filler layer 5 is as follows: ceramic, binder, and dispersant are coated onto at least one surface of the current collector 1 and the active material layer 3 in a ratio of 90-96:2-5:0.5-2, forming the first ceramic filler layer 4 and the second ceramic filler layer 5, respectively. The dispersant disperses the ceramic to form the slurry. The binder increases the viscosity, making it easier to coat onto the electrode surface and preventing direct contact between the positive and negative electrodes when there is an internal short circuit at the tab group, thus providing protection.

[0045] In one embodiment of the present invention, the end of the active material layer 3 has a thinning region 6, and the thinning region 6 is provided with a second ceramic filler layer 5, so that the active material layer 3 forms a flat surface. The provision of the second ceramic filler layer 5 in the thinning region 6 fills the thickness of the thinning region 6, so that the active material layer forms a more uniform and flat surface as a whole.

[0046] In one embodiment of the present invention, in the vertical cross-section of the thinned region 6, the sum of the thickness of the active material layer of the thinned region 6 and the thickness of the second ceramic filler layer 5 is equal to the thickness of the active material layer 3 in the non-thinned region. By ensuring that the sum of the thickness of the active material layer 3 and the thickness of the second ceramic filler layer 5 in the vertical cross-section of the thinned region 6 equals the overall thickness of the active material layer 3, the second ceramic filler layer 5 effectively enhances structural stability and safety. This design significantly improves impact resistance, deformation resistance, and extends service life, representing a significant advancement in battery technology optimization.

[0047] In one embodiment of the present invention, the width of the second ceramic filling layer 5 is a, and the thickness of the active material layer 3 is c, where a and c satisfy the relationship: a / c = 0.003 to 0.6;

[0048] In one embodiment of the present invention, the thickness of the second ceramic filling layer 5 is b, and the width of the active material layer 3 is d, where b and d satisfy the relationship: b / d = 0.005~0.5.

[0049] In one embodiment of the present invention, the width of the first ceramic filler layer 4 is A, and a and A satisfy the relationship: a / A = 0.8~1.2; if the ratio is too large, the safety protection function will be lost, and if the ratio is too small, it will affect the welding of the external electrode tabs and lead to scrap.

[0050] In one embodiment of the present invention, the thickness of the first ceramic filler layer 4 is B, and b and B satisfy the relationship: b / B = 0.8~1.2. An excessively large ratio will cause the top of the battery to bulge, while an excessively small ratio will cause the top of the battery to sink, both resulting in an uneven battery surface and severe deformation after repeated use.

[0051] In one embodiment of the present invention, A is 1-3 mm;

[0052] In one embodiment of the present invention, a is 1 to 3 mm.

[0053] In one embodiment of the present invention, B is 0.5–10 μm;

[0054] In one embodiment of the present invention, b is 0.5 to 10 μm.

[0055] In one embodiment of the present invention, the thickness ratio of the current collector 1, the safety undercoat 2, and the active material layer 3 is 6–12:0.5–20:20–100. This thickness ratio ensures that the current collector 1 has sufficient strength and conductivity to effectively collect and transmit current, improving the overall performance of the battery. Simultaneously, the active material layer has sufficient thickness to store more energy, thereby increasing the battery's capacity and range. This reasonable thickness ratio configuration results in excellent performance in terms of energy density, safety, and cycle life.

[0056] In one embodiment of the present invention, the thickness of the current collector 1 is 6-12 μm;

[0057] In one embodiment of the present invention, the thickness of the safety primer 2 is 0.5–20 μm;

[0058] In one embodiment of the present invention, the thickness of the active material layer 3 is 20–100 μm.

[0059] In a second aspect of the present invention, a secondary battery is also provided, comprising a positive electrode, a negative electrode, and a separator, wherein the positive electrode is the aforementioned composite electrode.

[0060] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on this utility model are within the protection scope of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. A composite pole piece characterized by, The application relates to a positive electrode sheet, comprising: a current collector; a safety primer layer arranged on at least one surface of the current collector; and an active material layer arranged on an outer surface of the safety primer layer; wherein the current collector has an empty foil area, the empty foil area is provided with a tab, and at least one surface of a root of the tab is provided with a first ceramic filling layer; the end of the active material layer has a thinning area, the thinning area is provided with a second ceramic filling layer, and the active material layer forms a flat surface; in a vertical section of the thinning area, the sum of the thickness of the active material layer of the thinning area and the thickness of the second ceramic filling layer is equal to the thickness of the active material layer of a non-thinning area; the width of the second ceramic filling layer is a, the width of the active material layer is c, and a / c=0.003-0.6; and / or the thickness of the second ceramic filling layer is b, the thickness of the active material layer is d, and b / d=0.005-0.5; the width of the first ceramic filling layer is A, and a / A=0.8-1.2; and / or the thickness of the first ceramic filling layer is B, and b / B=0.8-1.2; A is 1-3 mm; and / or a is 1-3 mm; B is 0.5-10 um; and / or b is 0.5-10 um; the thickness ratio of the current collector, the safety primer layer and the active material layer is 6-12:0.5-20:20-100; the thickness of the current collector is 6-12 um; the thickness of the safety primer layer is 0.5-20 um; and / or the thickness of the active material layer is 20-100 um. The positive electrode sheet is the composite electrode sheet as claimed in any one of claims 1-9. ​ ​ ​ 2. The composite pole piece of claim 1, wherein, ​ 3. The composite pole piece of claim 2, wherein, ​ 4. The composite pole piece of claim 2, wherein, ​ ​ 5. The composite pole piece of claim 4, wherein, ​ ​ 6. The composite pole piece of claim 5, wherein, ​ ​ 7. The composite pole piece of claim 5, wherein, ​ ​ 8. The composite pole piece of claim 1, wherein, ​ 9. The composite pole piece of claim 1, wherein, ​ ​ ​ 10. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, and a separator, characterized by ​

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