Pole piece and battery structure
By setting a containment cavity in the current collector coating area and filling it with expandable material, the problem of current transmission during thermal runaway of secondary batteries is solved, thereby improving the safety of the battery structure and reducing lithium plating.
Patent Information
- Application Number
- CN202520531922.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-03-24
AI Technical Summary
Existing secondary batteries cannot effectively block current transmission during thermal runaway, resulting in high safety risks. Existing improvement methods are either costly or have limited effectiveness.
A cavity is provided in the coating area of the current collector and filled with an expandable material, such as thermally expandable microspheres, to rapidly expand and lift the active material in the event of thermal runaway, thereby separating it from the current collector and blocking current transmission.
It effectively suppresses the spread of thermal runaway, improves the safety of the battery structure, reduces lithium plating, and lowers the risk of internal short circuits in the battery.
Smart Images
Figure CN224683093U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery technology, and more specifically, to an electrode and a battery structure. Background Technology
[0002] Rechargeable batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their high energy density and long cycle life. However, under extreme conditions (such as overcharging, over-discharging, short circuits, and thermal runaway), rechargeable batteries are prone to internal short circuits, which can lead to thermal runaway. This not only causes a sharp decline in battery performance but may also result in safety accidents such as fires and explosions. The root cause of thermal runaway is the intensified chemical reactions caused by the increased internal temperature of the battery, and the continuous transmission of current is a key factor that exacerbates this process.
[0003] In existing technologies, the current collector in secondary batteries is typically a metal foil or a composite current collector (a sandwich structure of "metal-polymer base film-metal"), used to collect and transmit the current generated by the active material layer. However, when the battery experiences thermal runaway, the metal current collector cannot effectively block current transmission, causing the internal temperature of the battery to continue to rise. This intensifies the reaction between the active material and the electrolyte, further accelerating the thermal runaway process and posing a significant threat to battery safety. Although some attempts have been made in the industry, such as adding a barrier layer to the current collector or using special materials to improve its flame retardancy, these methods often have limited effectiveness or increase the manufacturing cost and complexity of the battery, and have not yet achieved a breakthrough in improving battery safety. Utility Model Content
[0004] The main objective of this invention is to provide an electrode and battery structure that solves the problem that existing battery structures cannot effectively block current transmission when thermal runaway occurs.
[0005] To achieve the above objectives, according to one aspect of the present invention, a current collector is provided, comprising a current collector body and an expandable element, wherein the current collector body has a coating region for coating an active material, and the coating region has a receiving cavity; the expandable element fills the receiving cavity, and the expandable element is used to rapidly expand and lift the active material in the event of thermal runaway of the battery structure, so that at least the lifted active material is separated from the current collector body, thereby blocking the transmission of current.
[0006] In one exemplary embodiment, the expandable material is a thermally expandable microsphere.
[0007] In one exemplary embodiment, the current collector is a positive current collector, the expandable material protrudes from the plane of the cavity opening, and the protrusion height of the expandable material does not exceed 5 μm; or, the current collector is a negative current collector, and the expandable material does not protrude from the plane of the cavity opening.
[0008] In one exemplary embodiment, the inner diameter of the receiving cavity ranges from 10 to 50 μm.
[0009] In one exemplary embodiment, there are multiple receiving cavities, and the shortest distance between any two adjacent receiving cavities is not less than 15 μm and not greater than 100 μm.
[0010] In one exemplary embodiment, there are multiple receiving cavities, which are evenly distributed in the coating area.
[0011] In one exemplary embodiment, a groove is formed on a portion of the surface of the coating area on at least one side in its thickness direction, the interior space of the groove forms a receiving cavity, and the surface of the coating area on the side with the groove is used to coat an active substance.
[0012] In one exemplary embodiment, the coating area has a through hole extending through the current collector body along the thickness direction, and the internal space of the through hole forms a receiving cavity.
[0013] According to another aspect of the present invention, an electrode is provided, comprising a current collector and an active material, wherein the current collector is the aforementioned current collector, and the active material is coated on a coating area of the current collector body.
[0014] According to another aspect of the present invention, a battery structure is provided, including an electrode, wherein the electrode is the electrode described above.
[0015] The present invention proposes a current collector, comprising a current collector body and an expandable material, wherein the current collector body has a coating area for coating an active material, and the coating area has a receiving cavity; the expandable material fills the receiving cavity, and the expandable material is used to rapidly expand and lift the active material when the battery structure experiences thermal runaway, so that at least the lifted active material is separated from the current collector body, thereby blocking the transmission of current.
[0016] By setting a cavity in the coating area and filling the cavity with expandable material, the expandable material can expand rapidly and effectively lift the active material when thermal runaway occurs in the battery structure. This allows at least the lifted active material to separate from the current collector body, thereby blocking the transmission of current and significantly suppressing the spread of thermal runaway, ensuring the safety of the battery structure. Attached Figure Description
[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings: Figure 1A cross-sectional structural schematic diagram of an electrode sheet according to an alternative embodiment of the present invention is shown; Figure 2 It shows Figure 1 A schematic diagram of the structure of the expandable material of the electrode after expansion.
[0018] The above figures include the following reference numerals: 10. Current collector body; 20. Active material; 30. Expandable material. Detailed Implementation
[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.
[0020] To address the problem that existing battery structures cannot effectively block current transmission during thermal runaway, this invention provides an electrode and a battery structure. The electrode includes a current collector and an active material 20. The current collector is one of the current collectors described above and below, and the active material 20 is coated on the coating area of the current collector body 10. The battery structure includes an electrode, which is one of the electrode types described above and below.
[0021] like Figure 1 and Figure 2 As shown, the electrode includes a current collector and an active material 20 coated on the current collector. The current collector includes a current collector body 10 and an expandable element 30. The current collector body 10 has a coating area for coating the active material 20 and has a receiving cavity. The expandable element 30 fills the receiving cavity and is used to rapidly expand and lift the active material 20 in the event of thermal runaway of the battery structure, so that at least the lifted active material 20 is separated from the current collector body 10, thereby blocking the transmission of current.
[0022] By providing a cavity in the coating area, the expandable material 30 is filled in the cavity, so that when thermal runaway occurs in the battery structure, the expandable material 30 can expand rapidly and effectively lift the active material 20, thereby separating at least the lifted active material 20 from the current collector body 10, thus blocking the transmission of current, significantly suppressing the spread of thermal runaway, and ensuring the safety of the battery structure.
[0023] It should be noted that in this application, the expandable material 30 is an insulating structure. This ensures that after the expandable material 30 lifts the active material 20, at least the lifted active material 20 is separated from the current collector body 10, and that the insulating structure of the expandable material 30 can further block current transmission.
[0024] It should be noted that in this application, the expandable material 30 is made of an insulating polymer material. This ensures that the expandable material 30 has good insulation and thermal expansion properties, enabling it to expand rapidly in high-temperature environments while maintaining the insulating properties of the material and effectively preventing current from passing through.
[0025] Preferably, the expandable material 30 is a thermally expandable microsphere. After heating, the thermally expandable microsphere can rapidly expand to tens of times its own volume, and the thermally expandable microsphere, after expanding to tens of times its own volume, is sufficient to lift the active material 20 while maintaining good insulation properties; the implementation effect is that the expandable material 30 can effectively expand in the event of thermal runaway, forming an effective current blocking layer.
[0026] It should be noted that in this application, the shape of the expandable material 30 is at least one of capsule shape, cylindrical shape, spherical shape, and ellipsoidal shape. In this way, by controlling the shape of the expandable material 30, its expansion effect during thermal runaway can be optimized. The capsule-shaped, cylindrical, spherical, and ellipsoidal expandable materials 30 can more uniformly push up the active material 20 during expansion, effectively preventing the occurrence of internal short circuits in the battery structure. The implementation effect is that the expandable material 30 can expand rapidly and uniformly when the battery structure experiences thermal runaway, forming an effective current barrier layer and preventing internal short circuits in the battery structure.
[0027] It should be noted that in this application, the current collector is a positive current collector, the expandable material 30 protrudes from the plane of the cavity opening, and the protrusion height of the expandable material 30 does not exceed 5μm; or, the current collector is a negative current collector, and the expandable material 30 does not protrude from the plane of the cavity opening. Thus, when the current collector is a positive electrode current collector, the active material 20 corresponds to the positive electrode active material. Since the expandable material 30 protrudes from the plane of the cavity opening, it extends beyond the thickness of the current collector body 10. The expandable material 30 that extends beyond the current collector body 10 occupies the upper space of the current collector body 10, which can reduce the coating amount of the positive electrode active material and increase the CB value (the ratio of negative electrode capacity to positive electrode capacity), thus helping to reduce lithium plating. When the current collector is a negative electrode current collector, the active material 20 corresponds to the negative electrode active material. Since the expandable material 30 does not protrude from the plane of the cavity opening, it is recessed in the thickness of the current collector body 10, which allows some of the negative electrode active material to be accommodated in the cavity. This also increases the CB value (the ratio of negative electrode capacity to positive electrode capacity), thus helping to reduce lithium plating.
[0028] It should be noted that, in this application, the inner diameter of the receiving cavity can range from 10 to 50 μm.
[0029] It should be noted that in this application, there are multiple receiving cavities, and the shortest distance between any two adjacent receiving cavities is not less than 15 μm and not more than 100 μm. This optimizes the shortest distance between adjacent receiving cavities, preventing them from being too large and thus failing to effectively block current transmission, while also preventing them from being too small and resulting in insufficient overall structural strength of the current collector, which could easily lead to breakage during the rolling process of the electrode.
[0030] It should be noted that in this application, there are multiple cavities, which are evenly distributed over the coating area. This ensures that the active material 20 can be lifted as uniformly as possible, thereby ensuring the reliability of blocking current transmission.
[0031] It should be noted that, in this application, the cross-sectional area of the expandable material 30 after expansion is larger than the cross-sectional area of the cavity opening, in order to prevent the expandable material 30 from falling out of the cavity after expansion. This helps to prevent the expandable material 30 from falling out of the cavity after expansion, ensuring that the expandable material 30 can provide an effective resisting force for the active material 20, thereby ensuring that at least the pushed-up active material 20 can be effectively separated from the current collector body 10.
[0032] It should be noted that, in one embodiment of this application, a groove is formed on a portion of the surface of the coating area on at least one side in its thickness direction, and the internal space of the groove forms a receiving cavity. The surface of the coating area with the groove is used to coat the active material 20. Specifically, if both sides of the coating area are used to coat the active material 20, then grooves are provided on both sides of the coating area; if only one side of the coating area is used to coat the active material 20, then grooves are provided only on the side used to coat the active material 20.
[0033] It should be noted that, in another embodiment of this application, the coating area has a through hole penetrating the current collector body 10 along the thickness direction, and the internal space of the through hole forms a receiving cavity. In this case, active material 20 can be provided at both openings of the through hole, and the expandable material 30 in one through hole can simultaneously lift the active material 20 on both sides.
[0034] It should be noted that in this application, the expandable material 30 is implanted into the receiving cavity by dotting or spraying, and the expandable material 30 can be mixed with the adhesive and implanted into the receiving cavity, so that the expandable material 30 can be fixed in the receiving cavity by the adhesive.
[0035] The present invention proposes a current collector, which includes a current collector body 10 and an expandable element 30. The current collector body 10 has a coating area for coating an active material 20 and has a receiving cavity. The expandable element 30 fills the receiving cavity and is used to rapidly expand and lift the active material 20 when the battery structure experiences thermal runaway, so that at least the lifted active material 20 is separated from the current collector body 10, thereby blocking the transmission of current.
[0036] By providing a cavity in the coating area, the expandable material 30 is filled in the cavity, so that when thermal runaway occurs in the battery structure, the expandable material 30 can expand rapidly and effectively lift the active material 20, thereby separating at least the lifted active material 20 from the current collector body 10, thus blocking the transmission of current, significantly suppressing the spread of thermal runaway, and ensuring the safety of the battery structure.
[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0038] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.
[0039] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.
[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0041] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.
[0042] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. An electrode sheet, characterized in that, include: Current collector and active material (20), said current collector comprising: A current collector body (10) has a coating area, the active material (20) is coated on the coating area, and the coating area has a receiving cavity; An expandable material (30) is filled in the cavity. The expandable material (30) is used to rapidly expand and lift the active material (20) in the event of thermal runaway of the battery structure, so that at least the lifted active material (20) is separated from the current collector body (10) and the transmission of current is blocked.
2. The electrode sheet according to claim 1, characterized in that, The expandable material (30) is a thermally expandable microsphere.
3. The electrode sheet according to claim 1, characterized in that, The current collector is a positive current collector, and the expandable element (30) protrudes from the plane of the cavity opening of the receiving cavity, with the protrusion height of the expandable element (30) not exceeding 5 μm; or, The current collector is a negative current collector, and the expandable material (30) does not protrude from the plane of the cavity opening.
4. The electrode sheet according to claim 1, characterized in that, The inner diameter of the receiving cavity ranges from 10 to 50 μm.
5. The electrode sheet according to claim 1, characterized in that, The accommodating cavity is a plurality of accommodating cavities, and the shortest distance between any two adjacent accommodating cavities is not less than 15 μm and not greater than 100 μm.
6. The electrode sheet according to claim 1, characterized in that, The accommodating cavity is a plurality of accommodating cavities, which are evenly distributed in the coating area.
7. The electrode sheet according to claim 1, characterized in that, The coating area has a recessed portion of its surface in at least one side in the thickness direction to form a groove, the interior space of the groove forming the receiving cavity, and the surface of the coating area having the groove is used to coat the active substance (20).
8. The electrode sheet according to claim 1, characterized in that, The coating area has a through hole that penetrates the current collector body (10) along the thickness direction, and the internal space of the through hole forms the receiving cavity.
9. A battery structure, characterized in that, Includes an electrode sheet, wherein the electrode sheet is any one of claims 1 to 8.