Electrode assembly and secondary battery
By designing the protective electrode unit and the operating electrode unit structure of the electrode assembly, and combining them with a heat-resistant nanomaterial layer, the short-circuit problem of lithium batteries in the nail penetration test was solved, achieving higher safety and stability.
Patent Information
- Application Number
- CN202521858564.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-29
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-08-29
AI Technical Summary
Existing lithium batteries exhibit unstable short circuits during nail penetration tests, especially the chain reaction and short circuit hazards at the internal midpoint, which are severe. Current methods for improving the electrolyte cannot effectively guarantee battery safety.
The structure includes two protective electrode units and at least one operating electrode unit. The protective electrode unit consists of a first protective foil, a first diaphragm, and a single-sided coated electrode. The operating electrode unit consists of a positive electrode, a separator, and a negative electrode. The short-circuit protection capability is improved by designing polarity connections and a heat-resistant nanomaterial layer.
During the nail penetration test, the protective foil is short-circuited first to reduce chain reactions and heat generation, keeping thermal runaway within a controllable range, thereby improving the battery's nail penetration pass rate and reducing energy density loss.
Smart Images
Figure CN224683136U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of batteries, specifically relating to an electrode assembly and a secondary battery. Background Technology
[0002] The nail penetration test for lithium batteries is a safety test that assesses the internal short-circuit withstand capability of lithium-ion batteries and reflects their safety performance. To improve battery performance in the nail penetration test, current technology typically adds magnesium hydroxide to the electrolyte. When heated, magnesium hydroxide decomposes, releasing bound water and absorbing a large amount of latent heat, thus lowering the surface temperature of the material. Although magnesium hydroxide has both flame-retardant and smoke-suppressing functions, the existing electrode structure exhibits unstable short-circuit conditions during the nail penetration test. Furthermore, the chain reactions and short-circuit hazards originating in the middle of the battery's interior are usually the most severe. Therefore, optimizing the electrolyte composition cannot effectively guarantee the safety of the battery in the nail penetration test. Thus, a novel technical solution is urgently needed to address these issues. Utility Model Content
[0003] One of the objectives of this invention is to provide an electrode assembly that addresses the shortcomings of existing technologies, ensuring that the battery can safely and effectively withstand nail penetration tests.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] An electrode assembly includes two protective electrode units, each of the protective electrode units having a first protective foil, a first diaphragm and a single-sided coated electrode sheet stacked on top of each other, wherein the first protective foil and the single-sided coated electrode sheet have opposite polarities;
[0006] It also includes at least one operating electrode unit, which is stacked between two protective electrode units, at least a portion of which is electrically connected to the protective electrode unit, and a second diaphragm is provided between the operating electrode unit and the protective electrode unit;
[0007] The operating electrode unit includes a positive electrode, a separator, and a negative electrode stacked in sequence, with the separator disposed between adjacent positive and negative electrode sheets.
[0008] As an improvement to the electrode assembly of this utility model, the first protective foil and the positive electrode sheet have the same polarity and are electrically connected, and the single-sided coated electrode sheet has the same polarity and is electrically connected to the negative electrode sheet.
[0009] As an improvement to the electrode assembly of this utility model, the first protective foil and the negative electrode sheet have the same polarity and are electrically connected, and the single-sided coated electrode sheet has the same polarity and is electrically connected to the positive electrode sheet.
[0010] As an improvement to the electrode assembly of this utility model, the single-sided coated electrode is located on the side of the protective electrode unit closer to the second diaphragm, and the first protective foil is located on the side of the protective electrode unit away from the second diaphragm.
[0011] As an improvement to the electrode assembly of this utility model, the first protective foil is located on the side of the protective electrode unit closer to the second diaphragm, and the single-sided coated electrode is located on the side of the protective electrode unit away from the second diaphragm.
[0012] As an improvement of the electrode assembly of this utility model, at least one of the first protective foil, the first diaphragm and the second diaphragm is coated with a heat-resistant nanomaterial layer, and the heat-resistant nanomaterial layer is coated on one or both sides of the first protective foil, the first diaphragm or the second diaphragm.
[0013] As an improvement to the electrode assembly of this utility model, the protective electrode unit further has a second protective foil with a polarity opposite to that of the first protective foil, and the second protective foil, the third diaphragm, the first protective foil, the first diaphragm and the single-sided coated electrode are stacked in sequence.
[0014] As an improvement of the electrode assembly of this utility model, at least one of the positive electrode and the negative electrode is a double-sided coated electrode. The positive electrode includes a positive current collector and a positive active material layer coated on the positive current collector. The negative electrode includes a negative current collector and a negative active material layer coated on the negative current collector. The single-sided coated electrode includes a first current collector and a first active material layer coated on the first current collector. The first current collector faces the first separator, and the first active material layer faces the second separator or the packaging structure of the secondary battery.
[0015] The second objective of this utility model is to provide a secondary battery, including the electrode assembly described above.
[0016] As an improvement to the secondary battery of this utility model, the secondary battery further includes a packaging structure in which the electrode assembly is housed.
[0017] The beneficial effects of this utility model are as follows: The electrode assembly of this utility model includes two protective electrode units and at least one operating electrode unit. The operating electrode unit is stacked between the two protective electrode units, and at least a portion of the operating electrode unit is electrically connected to the protective electrode unit. A second separator is provided between the operating electrode unit and the protective electrode unit. The operating electrode unit includes a positive electrode sheet, a separator, and a negative electrode sheet stacked in sequence. A separator is provided between adjacent positive and negative electrode sheets. Each protective electrode unit has a first protective foil, a first separator, and a single-sided coated electrode sheet stacked in sequence. The first protective foil and the single-sided coated electrode sheet have opposite polarities. The first protective foil and the single-sided coated electrode sheet are used to form a short-circuit protection structure of the cell during the needle penetration test. The two protective electrode units play a short-circuit protection role on opposite sides of the electrode assembly. During needle penetration, the protective foil will short-circuit first. Due to its simpler structure, the chain reaction it can cause is small, and its heat generation is also relatively small, so that the thermal runaway of the electrode assembly is within a stable and controllable range, which greatly increases the needle penetration pass rate of the battery. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of this utility model.
[0019] Figure 2 This is a structural schematic diagram of Embodiment 4 of the present invention.
[0020] Figure 3 This is a structural schematic diagram of Embodiment 5 of the present invention.
[0021] Figure 4 This is a schematic diagram of the structure of the secondary battery of this utility model.
[0022] The components are: 1. Protective electrode unit; 11. First protective foil; 12. First diaphragm; 13. Single-sided coated electrode; 14. Second diaphragm; 15. Heat-resistant nanomaterial layer; 16. Second protective foil; 17. Third diaphragm; 2. Operating electrode unit; 21. Positive electrode; 22. Separator; 23. Negative electrode; 3. Packaging structure. Detailed Implementation
[0023] If certain terms are used in the specification and claims to refer to specific components, those skilled in the art will understand that manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. In this application, terms such as "first," "second," etc., are used only to distinguish different components and should not be construed as indicating or implying relative importance.
[0024] In the description of this utility model, it should be understood that the terms "upper", "lower", "top", "side", "front", "rear", "left", "right", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0025] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0026] In battery production, the main principle of the needle penetration test is to puncture or break the separator, causing a short circuit between the positive and negative electrodes, thus artificially creating a short circuit point inside the battery to simulate the short circuit phenomenon caused by conductive excess material inside the battery. However, the improvement effects of existing separators and electrolytes are not ideal, and safety primers can easily lead to significant energy density loss in the battery. Therefore, current technology lacks a solution that can pass the needle penetration test without introducing other significant adverse factors.
[0027] This utility model aims to provide a new structure that can pass the needle penetration test without introducing any significant adverse factors. The following is in conjunction with the appendix... Figures 1-2 The present invention will be further described in detail with reference to specific embodiments, but this is not intended to limit the present invention.
[0028] Example 1
[0029] An electrode assembly, such as Figure 1 As shown, it includes two protective electrode units 1, each of which has a first protective foil 11, a first diaphragm 12 and a single-sided coated electrode 13 stacked on top of each other. The first protective foil 11 and the single-sided coated electrode 13 have opposite polarities. There is at least one operating electrode unit 2, and one or more operating electrode units 2 are stacked between the two protective electrode units 1. At least a portion of each operating electrode unit 2 is electrically connected to the protective electrode unit 1. A second diaphragm 14 is provided between the operating electrode unit 2 and the protective electrode unit 1. The operating electrode unit 2 includes a positive electrode 21, a diaphragm 22 and a negative electrode 23 stacked in sequence. A diaphragm 22 is provided between adjacent positive electrode 21 and negative electrode 23.
[0030] The first protective foil 11 and the single-sided coated electrode 13 are used to form a short-circuit protection structure for the battery cell during the needle penetration test. The two protective electrode units 1 play a role in short-circuit protection on opposite sides of the electrode assembly. During the needle penetration test, the short circuit mainly occurs on the surface of the first protective foil 11. Since the structure of the first protective foil 11 is simpler and the chain reaction it can cause is small, and its heat generation is also relatively small, the thermal runaway of the electrode assembly is kept within a stable and controllable range, which greatly increases the needle penetration pass rate of the battery. Specific examples and verification results are provided below.
[0031] In the electrode assembly, the first protective foil 11 and the positive electrode 21 have the same polarity and are electrically connected. The single-sided coated electrode 13 and the negative electrode 23 have the same polarity and are electrically connected. That is, the first protective foil 11 can be an aluminum foil. The aluminum foil is electrically connected to the current collector of the positive electrode 21, and the first current collector of the single-sided coated electrode 13 is electrically connected to the current collector of the negative electrode 23. The positive tabs of each positive electrode 21 are connected, and the negative tabs of each negative electrode 23 are connected.
[0032] In the electrode assembly, the single-sided coated electrode 13 is located on the side of the protective electrode unit 1 closer to the second separator 14, and the first protective foil 11 is located on the side of the protective electrode unit 1 away from the second separator 14. The first protective foil 11 is directly disposed on the opposite sides of the electrode assembly to better ensure that the battery can pass the nail penetration test while no other obvious adverse factors are introduced into the battery structure.
[0033] Preferably, at least one of the positive electrode 21 and the negative electrode 23 is a double-sided coated electrode. Since each operating electrode unit 2 has a positive electrode 21, a separator 22, and a negative electrode 23 stacked sequentially, when the electrode assembly has n operating electrode units 2, and both the positive electrode 21 and the negative electrode 23 are double-sided coated electrodes, there are n double-sided electrodes for the positive electrode and n-1 double-sided electrodes for the negative electrode. There can be 8 to 16 operating electrode units 2.
[0034] Example 2
[0035] Unlike Embodiment 1, the first protective foil 11 and the negative electrode 23 have the same polarity and are electrically connected, and the single-sided coated electrode 13 has the same polarity and is electrically connected to the positive electrode 21; that is, the first protective foil 11 is a copper foil. Furthermore, when the electrode assembly has n operating electrode units 2, and both the positive electrode 21 and the negative electrode 23 are double-sided coated electrodes, there are n-1 double-sided electrodes for the positive electrode and n double-sided electrodes for the negative electrode.
[0036] The other structures in this embodiment are the same as those in Embodiment 1, and will not be described again here.
[0037] Example 3
[0038] Unlike Embodiment 1 or 2, the first protective foil 11 is located on the side of the protective electrode unit 1 closer to the second diaphragm 14, and the single-sided coated electrode 13 is located on the side of the protective electrode unit 1 away from the second diaphragm 14.
[0039] The other structures in this embodiment are the same as those in Embodiment 1 or 2, and will not be described again here.
[0040] Example 4
[0041] Unlike Examples 1-3, as Figure 2 As shown, in the electrode assembly, at least one of the first protective foil 11, the first diaphragm 12, and the second diaphragm 14 can be coated with a heat-resistant nanomaterial layer 15. The heat-resistant nanomaterial layer 15 can be made of nano-alumina or boehmite, and it does not react with the electrolyte while allowing the electrolyte to pass through its surface. The heat-resistant nanomaterial layer 15 further improves the safety of the needle penetration test.
[0042] Specifically, a heat-resistant nanomaterial layer 15 can be coated on both sides or one side of the first protective foil 11. The thickness of a single heat-resistant nanomaterial layer 15 can be 1.2 to 1.8 times the thickness of the first protective foil 11. Furthermore, the thickness of the first protective foil 11 is 12 μm to 30 μm, specifically 15 μm, 18 μm, 22 μm, 25 μm, or 28 μm.
[0043] The other structures in this embodiment are the same as those in embodiments 1 to 3, and will not be described again here.
[0044] Example 5
[0045] Unlike Examples 1-4, as Figure 3 As shown, the protective electrode unit 1 also has a second protective foil 16 with the opposite polarity to the first protective foil 11. The second protective foil 16, the third separator 17, the first protective foil 11, the first separator 12 and the single-sided coated electrode 13 are stacked in sequence, so that the short circuit during the needle penetration test is mainly shared by the first protective foil 11 and the second protective foil 16, and the battery is more likely to pass the needle penetration test.
[0046] The other structures in this embodiment are the same as those in embodiments 1 to 4, and will not be described again here.
[0047] Example 6
[0048] A secondary battery comprising the electrode assembly of any one of embodiments 1 to 5.
[0049] Among them, such as Figure 4 As shown, the secondary battery also includes a packaging structure 3, in which the electrode assembly is housed. Preferably, the secondary battery can be a pouch lithium-ion battery structure.
[0050] Ten to twenty identical battery structures were grouped together, with the same number of batteries in each group and the same capacity for each individual battery, ranging from 8Ah to 10Ah. The battery structures of different groups were different. A nail penetration test was performed on multiple identical battery structures in each group. The table below shows the nail penetration test results for multiple examples.
[0051]
[0052] Table 1
[0053] It is evident that, due to the simpler structure of the protective foil in the protective electrode unit, the chain reaction it can cause is smaller, and its heat generation is also relatively smaller, which keeps the thermal runaway of the electrode assembly within a stable and controllable range. At the same time, the energy density loss of the battery is also lower, thereby greatly increasing the needle penetration pass rate of the battery.
[0054] 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, the 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 the utility model are within the protection scope of the 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 the utility model.
Claims
1. An electrode assembly, characterized in that, include: Two protective electrode units (1), each of the protective electrode units (1) having a first protective foil (11), a first diaphragm (12) and a single-sided coated electrode (13) stacked on each other, wherein the first protective foil (11) and the single-sided coated electrode (13) have opposite polarities; At least one operating electrode unit (2) is stacked between two protective electrode units (1), at least a portion of the operating electrode unit (2) is electrically connected to the protective electrode unit (1), and a second diaphragm (14) is provided between the operating electrode unit (2) and the protective electrode unit (1); The operating electrode unit (2) includes a positive electrode (21), a separator (22) and a negative electrode (23) stacked in sequence, with the separator (22) disposed between adjacent positive electrode (21) and negative electrode (23).
2. The electrode assembly as described in claim 1, characterized in that: The first protective foil (11) and the positive electrode (21) have the same polarity and are electrically connected, and the single-sided coated electrode (13) has the same polarity and is electrically connected to the negative electrode (23).
3. The electrode assembly as described in claim 1, characterized in that: The first protective foil (11) and the negative electrode (23) have the same polarity and are electrically connected. The single-sided coated electrode (13) has the same polarity and is electrically connected to the positive electrode (21).
4. The electrode assembly according to any one of claims 1 to 3, characterized in that: The single-sided coated electrode (13) is located on the side of the protective electrode unit (1) closer to the second diaphragm (14), and the first protective foil (11) is located on the side of the protective electrode unit (1) away from the second diaphragm (14).
5. The electrode assembly according to any one of claims 1 to 3, characterized in that: The first protective foil (11) is located on the side of the protective electrode unit (1) closer to the second diaphragm (14), and the single-sided coated electrode (13) is located on the side of the protective electrode unit (1) away from the second diaphragm (14).
6. The electrode assembly according to any one of claims 1 to 3, characterized in that: At least one of the first protective foil (11), the first diaphragm (12) and the second diaphragm (14) is coated with a heat-resistant nanomaterial layer (15).
7. The electrode assembly according to any one of claims 1 to 3, characterized in that: The protective electrode unit (1) also has a second protective foil (16) with the opposite polarity to the first protective foil (11), and the second protective foil (16), the third diaphragm (17), the first protective foil (11), the first diaphragm (12) and the single-sided coated electrode (13) are stacked in sequence.
8. The electrode assembly according to any one of claims 1 to 3, characterized in that: At least one of the positive electrode (21) and the negative electrode (23) is a double-sided coated electrode.
9. A secondary battery, characterized in that: Includes the electrode assembly as described in any one of claims 1 to 8.
10. The secondary battery as described in claim 9, characterized in that: It also includes a packaging structure (3), in which the electrode assembly is housed.