A heat dissipation assembly for lithium battery roll core

Abstract

The utility model relates to a kind of heat dissipation components for lithium battery roll core, heat dissipation component includes first heat dissipation film and second heat dissipation film, first heat dissipation film is clamped between two adjacent roll cores, and the two surfaces of first heat dissipation film along thickness direction are respectively attached with the surface of corresponding side roll core;Second heat dissipation film is located at the two sides of first heat dissipation film, and second heat dissipation film is attached to the inner wall of shell, and the shell is used to accommodate several roll cores.The heat dissipation component of the utility model adopts ultra-thin design, is directly attached to the inner wall of shell or clamped between adjacent roll cores, under the premise that not extra occupy the limited space inside battery, without affecting the compactness of roll core assembly, the heat generated by roll core is quickly exported to external heat dissipation system by efficient heat conduction.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, and specifically to a heat dissipation component for lithium battery cores. Background Technology

[0002] As the global energy structure shifts towards cleaner and lower-carbon energy, lithium-ion batteries, with their significant advantages such as high energy density, long cycle life, and no memory effect, have become a core energy supply component in electric vehicles, energy storage systems, and portable electronic devices. However, during charging and discharging, lithium-ion batteries inevitably undergo electrochemical reactions and ohmic losses, continuously generating heat. This is especially true for batteries with multi-core or stacked core structures, where the large number and dense arrangement of core units result in narrow internal heat dissipation channels, making it easy for heat to accumulate internally, leading to an overall increase in battery temperature and even the formation of localized hot spots. If this heat cannot be effectively dissipated to the external environment in a timely manner, it will cause a series of serious problems.

[0003] Application Publication Number: CN 111244531 A, Application Date: March 31, 2020, Invention Title: A Core-Mounted Composite Insulating and Thermally Conductive Film for Lithium-ion Batteries and its Preparation Method. This invention relates to a core-mounted composite insulating and thermally conductive film for lithium-ion batteries and its preparation method, comprising a substrate, an insulating layer, and an adhesive. The substrate is a double-sided glossy metal foil, and the insulating layer is a polyimide film filled with boron nitride nanoparticles. The boron nitride-filled polyimide insulating film is non-flammable and can improve battery safety performance by replacing existing PP or PET insulating films. The core-mounted composite insulating and thermally conductive film for lithium-ion batteries of this invention has excellent thermal conductivity and safety performance, can quickly conduct heat from the middle of the battery cell to the surface of the aluminum shell, and reduce the temperature gradient inside the battery, significantly improving the problem of poor heat dissipation performance of large-capacity batteries.

[0004] The aforementioned prior art features thermally conductive films positioned above the top and below the bottom of the core, and these films are composed of a substrate, an insulating layer, and an adhesive. This design presents two problems: First, an excessively thick thermally conductive film occupies the already limited space inside the lithium battery, further reducing the assembly allowance between the core and the casing, thus affecting the compactness of the battery's internal structure. Second, the thickness resulting from the composite structure reduces the compressibility of the film itself, potentially making it difficult to adapt to minor deformations of the internal structure during battery assembly or subsequent use, thereby affecting heat dissipation stability or structural safety. Utility Model Content

[0005] In view of the shortcomings of the existing technology, such as the thicker membrane and reduced compressibility, the purpose of this utility model is to provide a heat dissipation component for lithium battery cores that reduces space occupation and improves conduction efficiency.

[0006] The technical solution provided by this utility model is as follows:

[0007] A heat dissipation assembly for lithium battery cores, the heat dissipation assembly comprising,

[0008] A first heat dissipation film is sandwiched between two adjacent cores, and the two surfaces of the first heat dissipation film along the thickness direction are respectively attached to the corresponding core surfaces.

[0009] The second heat dissipation film is located on both sides of the first heat dissipation film and is attached to the inner wall of the housing, which is used to accommodate several cores.

[0010] The first heat dissipation film is directly sandwiched between two adjacent cores, allowing it to directly contact the core heat-generating area of ​​the core. Compared to traditional external heat dissipation methods that require indirect heat transfer through the casing, the heat transfer path is greatly shortened. The second heat dissipation film is attached to the inner wall of the casing that houses several cores, absorbing the heat conducted to the vicinity of the casing by the first heat dissipation film and quickly dissipating it through heat exchange between the casing and the external environment.

[0011] Furthermore, along the stack height direction of the plurality of cores, the height of the second heat dissipation film is consistent with the height of the stack formed by the plurality of cores. If the height of the second heat dissipation film is shorter than the height of the stack, the uncovered area at the top or bottom of the stack is prone to forming a "vertical heat dissipation blind zone" because heat cannot be conducted to the heat dissipation film, resulting in an increase in the temperature difference between the upper and lower ends of the stack.

[0012] Furthermore, along a direction perpendicular to the surface of the second heat dissipation film, the orthographic projection of the first heat dissipation film onto the surface of the second heat dissipation film completely falls within the surface area of ​​the second heat dissipation film. The first heat dissipation film, acting as an internal heat source between adjacent cores, absorbs heat from the cores and transfers it to the housing through contact with the second heat dissipation film, ultimately dissipating it to the outside. The design of the orthographic projection completely falling within the second heat dissipation film ensures that all the heat absorbed by the first heat dissipation film is received by the second heat dissipation film, achieving a seamless connection between "internal conduction and external dissipation," effectively improving heat transfer efficiency.

[0013] Furthermore, the thickness of both the first and / or second heat dissipation films ranges from 0.03 mm to 1 mm. If the thickness of the heat dissipation film is less than 0.03 mm, micropores are likely to exist inside the material, leading to a significant decrease in thermal conductivity, and the structure of an excessively thin film has extremely low strength. If the thickness of the heat dissipation film exceeds 1 mm, the heat conduction path inside the film becomes longer, and the interlayer thermal resistance is superimposed, which actually reduces the heat dissipation efficiency.

[0014] Furthermore, the top of the core located at the top of the stack directly contacts the inner wall of the housing; the bottom of the core located at the bottom of the stack directly contacts the inner wall of the housing. This design, where the core directly contacts the inner wall of the housing, shortens the heat transfer path and reduces thermal resistance.

[0015] Furthermore, the first heat dissipation film is a graphene oxide film.

[0016] Furthermore, the first heat dissipation film adopts a one-, two-, or three-layer structure, with each layer not exceeding 0.05mm in thickness. Traditional multi-layer thick-film heat dissipation structures have single-layer thicknesses exceeding 0.1mm, easily compressing assembly space and leading to loose core bonding or difficulties in shell encapsulation. In contrast, the design with each layer not exceeding 0.05mm, even with a three-layer structure, results in a total thickness of only 0.15mm, with each single layer less than 0.05mm, far lower than the thickness of traditional heat dissipation films. This design maximizes the assembly allowance between cores, avoiding the problem of crowded core arrangement caused by excessively thick heat dissipation films.

[0017] Furthermore, the first heat dissipation film is a thermally conductive graphite sheet.

[0018] Furthermore, the first heat dissipation film adopts a one-, two-, three-, or four-layer structure, with each layer having a thickness of approximately 0.03 mm. This design avoids the accumulation of thermal resistance caused by excessive interlayer interfaces by limiting the number of layers to 1 to 4. At the same time, each layer is ultra-thin and uses thermally conductive graphite sheets with low internal porosity and low thermal resistance, which can quickly dissipate the heat generated by adjacent cores and avoid local heat accumulation between cores.

[0019] Furthermore, the first and second heat dissipation films are integrally formed. This integral design can be manufactured using a single high thermal conductivity material or a homogeneous composite material, ensuring that the thermal conductivity of the first and second heat dissipation films is completely consistent, and that the heat transfer rate within the film is uniform and stable. This avoids insufficient local heat dissipation due to differences in thermal conductivity, ensures temperature uniformity throughout the battery, and extends the cycle life of the lithium battery.

[0020] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0021] (1) The heat dissipation component of this utility model adopts an ultra-thin design, which is directly attached to the inner wall of the shell or sandwiched between adjacent cores. Without occupying the limited space inside the battery or affecting the compactness of the core assembly, the heat generated by the core is quickly conducted to the external heat dissipation system through efficient heat conduction.

[0022] (2) This utility model can adopt a differentiated heat conduction design for a core stack formed by stacking several cores: the top end face of the core located at the top of the core stack is directly in contact with the top inner wall of the shell after being cleaned; similarly, the bottom end face of the core located at the bottom of the core stack is also directly in contact with the bottom inner wall of the shell after being cleaned. Attached Figure Description

[0023] Figure 1This is a schematic diagram of two cores stacked in one embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the core and heat dissipation assembly structure in one embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the structure of a first heat dissipation film layer in one embodiment of this application;

[0026] Figure 4 This is a schematic diagram of four cores stacked in one embodiment of this application;

[0027] Figure 5 This is a schematic diagram of a three-layer first heat dissipation film structure in one embodiment of this application.

[0028] Explanation of the labels in the diagram:

[0029] First heat dissipation film 1;

[0030] Second heat dissipation film 2;

[0031] Core 3;

[0032] Shell 4. Detailed Implementation

[0033] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0034] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this utility model. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0035] During the charging and discharging process of lithium battery cores, heat is generated by the reaction of positive and negative electrode materials, the migration of electrolyte ions, and internal resistance loss. Especially during high-rate charging and discharging or high-current discharging, heat will accumulate rapidly inside the core.

[0036] Example 1

[0037] This application discloses a heat dissipation component for lithium battery cores, adapted to the compact structure of multi-layer stacked cores 3. The heat dissipation component adopts an ultra-thin design, directly attached to the inner wall of the housing 4 or sandwiched between adjacent cores 3. Without occupying additional limited internal space of the battery or affecting the compactness of the core assembly, it rapidly conducts heat generated by the core to the external heat dissipation system through efficient heat conduction. This active temperature control method can prevent the local temperature of the core from exceeding the material tolerance threshold (such as the thermal shrinkage temperature of the separator and the decomposition temperature of the electrolyte), thereby effectively extending the cycle life and overall service life of the lithium battery.

[0038] The heat dissipation assembly includes a first heat dissipation film 1 and a second heat dissipation film 2, which are arranged in a spatially perpendicular relationship. The first heat dissipation film 1 is sandwiched between two adjacent lithium battery cores 3, and the two opposing surfaces of the first heat dissipation film 1 along the thickness direction are tightly attached to the outer surface of the corresponding side core 3 to realize the direct conduction of heat from the core 3 to the first heat dissipation film 1.

[0039] Two second heat dissipation films 2 are provided, respectively located on both sides of the first heat dissipation film 1. The surface of the second heat dissipation film 2 that is relatively far away from the first heat dissipation film 1 is attached to the inner wall of the housing 4. The housing 4 has a structure with a accommodating cavity for accommodating several stacked cores 3 and the above-mentioned heat dissipation components.

[0040] More specifically, thermally conductive adhesive is applied between the contact surfaces of the second heat dissipation film 2 and the inner wall of the housing 4. The thermally conductive adhesive fills the tiny gaps between the contact surfaces, reducing the interfacial thermal resistance and thus significantly improving the heat transfer efficiency of the second heat dissipation film 2 to the housing 4. The housing 4 is preferably made of aluminum. Utilizing the excellent thermal conductivity of aluminum, the heat conducted by the second heat dissipation film 2 can be quickly diffused to the outside of the housing 4, further improving the overall heat dissipation effect.

[0041] Along the stacking height direction of several cores 3 (i.e., the vertical direction formed by the layering of cores 3), the height of the second heat dissipation film 2 is consistent with the height of the core stack formed by stacking several cores 3. However, specifically, the height of the second heat dissipation film 2 may be slightly higher or slightly lower than the height of the core stack. The difference is usually controlled within the range of 0.5 to 2 mm to ensure that the second heat dissipation film 2 can fully cover the height range of the core stack and avoid heat from local areas of the core stack not being able to be conducted through the second heat dissipation film 2 due to height deviation.

[0042] Along the direction perpendicular to the surface of the second heat dissipation film 2, the orthographic projection of the first heat dissipation film 1 onto the surface of the second heat dissipation film 2 falls completely within the surface range of the second heat dissipation film 2. This means that the lateral dimension of the first heat dissipation film 1 (the dimension perpendicular to the stacking height direction) does not exceed the lateral dimension of the second heat dissipation film 2, ensuring that all the heat conducted by the first heat dissipation film 1 can be transferred to the second heat dissipation film 2, avoiding heat leakage due to the projection exceeding the limit, and further improving the heat conduction efficiency of the heat dissipation component.

[0043] If the projected area of ​​the first heat dissipation film 1 exceeds the range of the second heat dissipation film 2, the heat in the excess portion cannot be directly transferred to the second heat dissipation film 2. Instead, it can only be indirectly conducted through the core 3 or the air inside the battery. This not only increases the heat transfer resistance but also easily forms a heat "stagnation zone" in the excess area, leading to a local temperature increase. In contrast, the design where the projected area falls entirely within the second heat dissipation film 2 allows all the heat absorbed by the first heat dissipation film 1 to be received by the second heat dissipation film 2, achieving a seamless connection between "internal conduction and external dissipation" and effectively improving heat transfer efficiency.

[0044] Meanwhile, in order to optimize costs while ensuring basic heat dissipation, a differentiated heat conduction design can be adopted for the core stack formed by stacking several cores 3: the top end face of the core 3 located at the top of the core stack is directly in contact with the top inner wall of the housing 4 after cleaning treatment; similarly, the bottom end face of the core 3 located at the bottom of the core stack is also directly in contact with the bottom inner wall of the housing 4 after cleaning treatment.

[0045] The core advantage of this design is that it eliminates the need for additional heat dissipation films between the top core 3, bottom core 3 and the inner wall of the housing 4. By directly bonding the core end face to the metal housing (such as the preferred aluminum housing), the heat generated by the top core 3 and bottom core 3 is directly dissipated using the thermal conductivity of the housing 4 itself. This simplifies the structure of the heat dissipation components, reduces the number of heat dissipation films used to lower material costs, and avoids the increased assembly complexity caused by the stacking of multiple heat dissipation structures.

[0046] Meanwhile, the direct contact between the end face of the core 3 and the inner wall of the housing 4 can reduce the interfacial thermal resistance on the heat conduction path (compared to indirect conduction through the heat dissipation film), ensuring that the heat of the top and bottom core 3 can be efficiently transferred to the housing 4, taking into account both cost savings and basic heat dissipation requirements.

[0047] The thickness of the first heat dissipation film 1 and / or the second heat dissipation film 2 is controlled within the range of 0.03 mm to 1 mm.

[0048] If the thickness of the heat dissipation film is less than 0.03mm, on the one hand, the amount of film material used is too small, the heat conduction path is too short, and there are likely to be tiny pores inside the material, resulting in a significant decrease in heat conduction efficiency and inability to effectively transfer heat. On the other hand, the structural strength of an excessively thin film is extremely low, making it prone to tearing and damage during battery assembly, and it is difficult to maintain adhesion when the core deforms during charging and discharging, leading to failure of the heat dissipation function. 0.03mm, as the minimum thickness, ensures that the film has basic thermal conductivity and structural strength, meeting the usage requirements of low-power scenarios.

[0049] If the thickness of the heat dissipation film exceeds 1mm, although the amount of material used increases, the heat conduction path inside the film becomes longer, and the thick film is prone to problems with loose interlayer bonding, resulting in the superposition of interlayer thermal resistance, which actually reduces the heat dissipation efficiency; at the same time, the excessively thick film will severely compress the internal space of the lithium battery.

[0050] From the perspective of heat conduction efficiency and structural adaptability, the thickness of the heat dissipation film needs to be strictly controlled. If the thickness exceeds 1mm, the thermal resistance of the film itself will increase linearly with the increase of thickness. The thermal resistance formula is R=δ / λ, where δ is the thickness and λ is the thermal conductivity. When λ is fixed, the larger δ is, the larger R is, which leads to a significant reduction in the heat conduction rate in the film and directly weakens the heat dissipation efficiency.

[0051] On the other hand, an excessively thick heat dissipation film will occupy additional limited space inside the lithium battery, compressing the assembly allowance between the core 3 and the housing 4. It will also reduce the compressibility of the film, a crucial characteristic for the heat dissipation film to adhere to the minute irregularities on the core surface and eliminate interfacial gaps. Decreased compressibility leads to a reduced bond tightness between the heat dissipation film and the core 3 or housing 4, indirectly increasing interfacial thermal resistance. Furthermore, a thicker film will increase the amount of raw materials used, driving up material costs and overall production costs.

[0052] Therefore, while meeting the strength requirements of the heat dissipation film itself, such as resisting the stacking pressure of the core 3 and the tensile or frictional damage during the assembly process, the thickness of the heat dissipation film should be minimized as much as possible: a thinner film can reduce its own thermal resistance, improve the thermal conduction efficiency, reduce space occupation, ensure good interface adhesion, and control costs, thereby maximizing the role of the heat dissipation film in the thermal management of lithium batteries.

[0053] The first heat dissipation film 1 is preferably made of graphene oxide film, which has both high thermal conductivity and electrical insulation, perfectly meeting the dual requirements of "efficient heat conduction + short circuit prevention" between the cores. From a structural design perspective, the first heat dissipation film 1 can adopt a stacked structure of one, two, or three layers according to the heat conduction requirements after the cores 3 are stacked. In order to avoid occupying too much assembly space between the cores and to ensure the tightness of the film and the surface of the cores 3, the thickness of each layer of graphene oxide film is controlled within 0.05mm.

[0054] The multi-layer structure design can further improve heat conduction efficiency without significantly increasing the overall thickness, while enhancing the mechanical strength of the membrane, such as tensile and tear resistance, and adapting to stress changes caused by slight expansion and contraction during the charging and discharging of the core 3.

[0055] The thermal conductivity of the graphene oxide film is 1940±113 W / (m·K), and the electrical conductivity is less than 1×10⁻⁶. -9 S / cm. It can quickly absorb and conduct the heat generated by adjacent cores 3 to the second heat dissipation film 2 or the shell 4; at the same time, it is an excellent electrical insulating material, which can effectively block the current conduction between adjacent cores, avoid the risk of positive and negative short circuit caused by the conductivity of the heat dissipation film, and take into account both efficient heat dissipation and safety protection functions.

[0056] Example 2

[0057] This embodiment is an alternative design for the first heat dissipation film 1 based on Embodiment 1.

[0058] Among them, the first heat dissipation film 1 is made of thermally conductive graphite sheet. With its excellent in-plane thermal conductivity and ultra-thin characteristics, this material can adapt to the narrow assembly space between the cores and meet the dual requirements of efficient heat conduction and electrical insulation between adjacent cores 3.

[0059] From a structural design perspective, the first heat dissipation film 1 can flexibly adopt a stacked structure of one, two, three, or four layers according to the actual working conditions such as the heat generation and stacking pressure of the core 3. In order to avoid occupying too much space between cores and to ensure the tight adhesion between the film and the surface of the core 3, the thickness of each layer of thermally conductive graphite sheet is about 0.03mm.

[0060] The multi-layer structure design can not only further improve the heat conduction efficiency through the superposition effect without significantly increasing the overall thickness (for example, the thermal conductivity of a four-layer structure is significantly better than that of a single layer), but also enhance the mechanical toughness of the membrane, avoid damage to the heat dissipation membrane due to slight expansion and contraction during the charging and discharging of the core, and improve long-term stability.

[0061] The thermal conductivity of the thermally conductive graphite sheet is 1500–1900 W / (m·K), and its electrical conductivity is less than 1×10⁻⁶. -9 S / cm.

[0062] It is worth noting that the first heat dissipation film 1 and the second heat dissipation film 2 preferably adopt an integrated molding structure. This design can eliminate the interface gap at the splicing point of the two, avoid the increase in thermal resistance caused by splicing, simplify the assembly process of the heat dissipation components, reduce the number of parts, and improve the overall structural stability. In particular, during the stacking of the core 3 and the assembly of the shell, the integrated heat dissipation film can better adapt to the spatial dimensions of the core 3 and the shell 4, reducing the risk of heat dissipation failure caused by assembly deviation.

[0063] Of course, the first heat dissipation film 1 and the second heat dissipation film 2 can also be directly connected in contact, as long as the heat transfer effect is met.

[0064] In terms of material selection, the first heat dissipation film 1 and the second heat dissipation film 2 can be selected from the same material or different materials according to their respective heat dissipation needs and working scenarios.

[0065] When the same high thermal conductivity insulating material is selected (such as both being thermally conductive graphite sheets or both being graphene oxide films), consistent heat dissipation performance can be guaranteed.

[0066] When the first heat dissipation film 1 is made of graphene oxide film and the second heat dissipation film 2 is made of thermally conductive graphite sheet, it can be used to match the heat dissipation requirements of different parts (such as the first heat dissipation film needing to fit the narrow space between the cores and the second heat dissipation film needing to fit the large area of ​​the inner wall of the shell), and at the same time, a balance between performance and cost can be achieved through differentiated material selection.

[0067] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A heat dissipation assembly for lithium battery cores, characterized in that: The heat dissipation components include, The first heat dissipation film (1) is sandwiched between two adjacent cores (3), and the two surfaces of the first heat dissipation film (1) along the thickness direction are respectively attached to the surface of the corresponding core (3); The second heat dissipation film (2) is located on both sides of the first heat dissipation film (1), and the second heat dissipation film (2) is attached to the inner wall of the housing (4), which is used to accommodate a number of cores (3).

2. A heat dissipation assembly for a lithium battery core according to claim 1, characterized in that: Along the stacking height direction of the plurality of cores (3), the height of the second heat dissipation film (2) is consistent with the height of the stack formed by the stacking of the plurality of cores (3).

3. A heat dissipation assembly for a lithium battery core according to claim 1, characterized in that: Along a direction perpendicular to the surface of the second heat dissipation film (2), the orthographic projection of the first heat dissipation film (1) onto the surface of the second heat dissipation film (2) falls completely within the surface area of ​​the second heat dissipation film (2).

4. A heat dissipation assembly for a lithium battery core according to claim 1, characterized in that: The thickness of the first heat dissipation film (1) and / or the second heat dissipation film (2) is in the range of 0.03 mm to 1 mm.

5. A heat dissipation assembly for a lithium battery core according to claim 2, characterized in that: The top of the core (3) located at the top of the stack is in direct contact with the inner wall of the housing (4); The core (3) located at the bottom of the stack has its bottom directly in contact with the inner wall of the housing (4).

6. A heat dissipation assembly for a lithium battery core according to claim 1, characterized in that: The first heat dissipation film (1) is a graphene oxide film.

7. A heat dissipation assembly for a lithium battery core according to claim 6, characterized in that: The first heat dissipation film (1) adopts a one-layer, two-layer, or three-layer structure, with each layer having a thickness of no more than 0.05 mm.

8. A heat dissipation assembly for a lithium battery core according to claim 1, characterized in that: The first heat dissipation film (1) is a thermally conductive graphite sheet.

9. A heat dissipation assembly for a lithium battery core according to claim 8, characterized in that: The first heat dissipation film (1) adopts a one-layer, two-layer, three-layer, or four-layer structure, with each layer having a thickness of approximately 0.03 mm.

10. A heat dissipation assembly for a lithium battery core according to claim 1, characterized in that: The first heat dissipation film (1) and the second heat dissipation film (2) are integrally formed.

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