Composite heat insulation structure between battery cells

Abstract

The utility model discloses a composite heat insulation structure between battery cells, which relates to the technical field of battery structures and comprises a first high-temperature-resistant layer and a second high-temperature-resistant layer which are formed by mica paper sheets, a uniform-temperature layer which is arranged in a clamping cavity and is formed by soluble composite cotton sheets, and a pre-tightening layer which is formed by silica gel strips, the first high-temperature-resistant layer and the second high-temperature-resistant layer are bonded or sewn to form a heat insulation barrier, so that heat transfer is inhibited; the temperature equalization layer balances the temperature between the battery cells through a phase change heat storage and capillary temperature equalization mechanism; the pre-tightening layer composed of the upper silica gel strip and the lower silica gel strip provides directional elastic pre-tightening force to adapt to the expansion and assembly tolerance of the power core. The composite heat insulation structure among the battery cells solves the problems of insufficient temperature resistance, poor temperature uniformity and failure of pre-tightening force of a traditional heat insulation structure, has the characteristics of capability of adapting to tolerances of various parts of a battery pack and adapting to dynamic strain of the battery cells, high reliability, low cost and light weight, and is suitable for heat protection among the battery cells of a power battery and an energy storage battery.

Description

Technical Field

[0001] This utility model relates to the field of battery structure technology, and in particular to a composite heat insulation structure between battery cells. Background Technology

[0002] With the rapid development of new energy vehicles, the safety of power batteries has become a core concern in the industry. Thermal insulation materials between battery cells need to effectively block heat transfer during thermal runaway to prevent heat propagation and chain reactions. However, existing thermal insulation materials for battery cells struggle to balance performance and cost, and face technical bottlenecks in areas such as temperature resistance, insulation, heat preservation, and pre-tightening.

[0003] (1) The contradiction between the material's high-temperature resistance and the control of the cold surface temperature

[0004] Currently, mainstream low-end thermal insulation materials, such as XPP and other polyolefin foams, have low application costs, but their temperature resistance is insufficient, typically below 300℃, and they are prone to softening and deformation at high temperatures, making it difficult to control the cold surface temperature below 200℃. While high-end materials such as aerogels have excellent thermal insulation performance, they are expensive, have aerospace-grade costs, poor flexibility, and cannot provide sufficient preload to accommodate variations in battery cell tolerances, making them susceptible to structural failure due to battery cell expansion.

[0005] (2) The complexity and cost of composite materials

[0006] Some composite insulation solutions attempt to optimize performance through multi-layer structures, such as using aerogel and fiber felt composites, like fiberglass felt / aerogel sandwich structures. However, these solutions suffer from problems such as easy shedding of aerogel particles and high processing costs.

[0007] (3) The challenge of balancing light-blocking agents and compressive strength

[0008] To improve the high-temperature radiation blocking capability of thermal insulation materials, light-blocking agents such as SiC are often added. However, improper content and particle size distribution of the light-blocking agent can increase the thermal conductivity of the solid phase, thereby reducing the overall thermal insulation efficiency. For example, patent literature proposes to optimize radiation blocking by designing the particle size of SiC particles in layers, but this requires the use of sodium silicate colloid to enhance compressive strength, resulting in a complex material system and increased costs.

[0009] (4) Insufficient cell tolerance matching and rebound performance

[0010] During the charging and discharging process, the battery cell experiences dynamic stress due to expansion, requiring the insulation material to possess both resilience and structural stability. Existing elastic frame layers, such as polyurethane foam, can buffer expansion pressure, but the bonding interface between it and the flame-retardant layer is prone to failure due to high-temperature aging, and the hollow structure design may weaken the overall strength of the material, leading to a decrease in preload after long-term use.

[0011] Therefore, there is an urgent need to develop a composite thermal insulation structure that combines high temperature resistance, high resilience, low cost, adaptability to battery pack tolerances, and adaptability to dynamic strain of battery cells to solve the above-mentioned technical bottlenecks.

[0012] In summary, the existing technology has at least the following technical problems:

[0013] Existing cell insulation structures suffer from technical problems such as insufficient temperature resistance, uneven temperature distribution, and poor preload. Utility Model Content

[0014] The purpose of this utility model is to provide a composite thermal insulation structure between battery cells to solve the technical problems of insufficient temperature resistance, uneven temperature distribution, and poor pre-tightening force in existing battery cell thermal insulation structures, which makes it difficult to adapt to the tolerances of various parts of the battery pack and to adapt to the dynamic strain of the battery cells.

[0015] The various technical effects of the preferred technical solutions among the many technical solutions provided by this utility model are described in detail below.

[0016] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0017] This utility model provides a composite heat insulation structure between battery cells, including a first high-temperature resistant layer, a temperature equalization layer, a second high-temperature resistant layer, and a pre-tightening layer installed in the battery pack and located between the battery cells; the first high-temperature resistant layer and the second high-temperature resistant layer are bonded or sewn to form a clamping cavity, and the temperature equalization layer is disposed in the clamping cavity. The first high-temperature resistant layer and the second high-temperature resistant layer block the heat transmitted between the battery cells, and the temperature equalization layer absorbs the temperature between the battery cells with uniform storage capacity; the pre-tightening layer is provided outside the first high-temperature resistant layer and outside the second high-temperature resistant layer; the pre-tightening layer includes upper and lower parts, which are respectively disposed at the upper and lower ends of the first high-temperature resistant layer and the second high-temperature resistant layer in the height direction of the battery cells, and are used to provide elastic pre-tightening force between the battery cells and adapt to the tolerances of various parts in the battery pack.

[0018] In one embodiment, both the first high-temperature resistant layer and the second high-temperature resistant layer are mica paper sheets.

[0019] In one embodiment, the temperature equalization layer is a soluble composite cotton sheet.

[0020] In one embodiment, the soluble composite cotton sheet is evenly laid in the clamping cavity and has uniformly distributed temperature equalization holes.

[0021] In one embodiment, the upper and lower portions of the pre-tightening layer are respectively an upper silicone strip and a lower silicone strip with elasticity.

[0022] In one embodiment, the upper silicone strip and the lower silicone strip are fixed to the outside of the first high-temperature resistant layer and the outside of the second high-temperature resistant layer by means of adhesive bonding or welding.

[0023] In one embodiment, both the upper silicone strip and the lower silicone strip are provided with elastic sheets.

[0024] In one embodiment, the cross-sectional structure of the elastic sheet along its length is wavy.

[0025] The elastic sheet is a shape memory metal sheet; as the temperature between the battery cells increases, the cross-sectional shape of the elastic sheet in the length direction gradually changes from a wavy shape to a straight shape.

[0026] The beneficial effects of this utility model are as follows:

[0027] This utility model provides a composite heat insulation structure between battery cells, comprising: a first high-temperature resistant layer, a temperature equalization layer, a second high-temperature resistant layer, and a pre-tightening layer installed inside the battery pack and located between the battery cells; the first high-temperature resistant layer and the second high-temperature resistant layer are bonded or sewn to form a clamping cavity, the temperature equalization layer is disposed in the clamping cavity, the first high-temperature resistant layer and the second high-temperature resistant layer block the heat transmitted between the battery cells, and the temperature equalization layer absorbs the temperature between the battery cells with uniform storage capacity; the pre-tightening layer is disposed outside the first high-temperature resistant layer and outside the second high-temperature resistant layer; the pre-tightening layer includes upper and lower parts, the upper and lower parts of the pre-tightening layer are respectively disposed at the upper and lower ends of the first high-temperature resistant layer and the second high-temperature resistant layer in the height direction of the battery cells, for providing elastic pre-tightening force between the battery cells and adapting to the tolerances of various parts in the battery pack.

[0028] The first high-temperature resistant layer and the second high-temperature resistant layer are both mica paper sheets; the temperature equalization layer is a soluble composite cotton sheet; the pre-tightening layer is a silicone layer, and the upper and lower parts of the pre-tightening layer are respectively elastic upper silicone strips and lower silicone strips.

[0029] Compared to existing technologies

[0030] The composite thermal insulation structure between battery cells provided by this utility model effectively solves the core technical problems of insufficient temperature resistance, uneven temperature uniformity, and poor adaptability of pre-tightening force in existing battery cell thermal insulation structures through the synergistic thermal insulation, heat preservation, and elastic pre-tightening of the multi-layer structure. Specifically, it has the following advantages:

[0031] Enhanced high-temperature resistance and thermal runaway protection: The first and second high-temperature resistant layers are formed by combining mica paper sheets to create a cavity. This double-layer high-temperature resistant cavity structure forms a thermal barrier, significantly delaying the transfer of high temperatures during cell thermal runaway and ensuring the cold surface temperature remains stable below 200°C. Compared to traditional insulation structures using single polyolefin foam materials, the high-temperature resistance of mica paper sheets avoids the risk of softening and deformation of the insulation material between cells at high temperatures. This effectively blocks heat transfer between cells, improving the overall temperature resistance of the battery pack. Furthermore, this technology is significantly less expensive than aerogel insulation structures used in aerospace applications, combining economic efficiency and reliability.

[0032] Optimized temperature uniformity and thermal shock buffering: A soluble composite cotton layer is placed between two high-temperature resistant layers as a temperature uniformity layer. This layer can quickly absorb and evenly distribute the heat between the cells through phase change heat absorption and capillary diffusion, and evenly release the energy of the locally overheated areas of the cells to the adjacent areas, reducing the temperature gradient between different areas of the battery pack, avoiding local overheating, and ensuring the temperature uniformity inside the battery pack. This composite thermal insulation structure between cells can reduce the temperature difference between cells, effectively avoid the chain reaction caused by heat accumulation, and at the same time alleviate the dynamic impact of cell expansion on the thermal insulation structure.

[0033] Enhanced elastic preload adaptation and tolerance compatibility: Silicone strips are set as preload layers on the outside of the high-temperature resistant layer. The upper and lower silicone strips are fixed to both ends of the high-temperature resistant layer, respectively. The upper and lower silicone strips provide continuous elastic preload between the cells through their good elasticity and heat resistance. They continuously provide horizontal preload between the cells through elastic deformation, compensating for the gaps required for cell expansion during charging and discharging, as well as the assembly gaps of components inside the battery pack. They adapt to the tolerances of various parts inside the battery pack and the dynamic strain of the cells caused by temperature changes, ensuring the stability and reliability of the structure. Compared with the traditional integral elastic frame insulation structure, the local reinforcement scheme of the upper and lower silicone strips ensures resilience while avoiding the thickness redundancy caused by the material fully encasing the cells, making it more suitable for compact battery pack designs.

[0034] In summary, this composite thermal insulation structure between battery cells exhibits excellent performance in improving the high-temperature resistance, temperature uniformity, and pre-tightening force of the thermal insulation structure between battery cells. It can effectively adapt to the tolerances of various components within the battery pack and the dynamic strain of the battery cells as temperature changes, thereby enhancing the safety and reliability of the battery pack. Attached Figure Description

[0035] To more clearly illustrate the technical solution of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the composite thermal insulation structure between battery cells of this utility model;

[0037] Figure 2 yes Figure 1 A magnified view of part A in the middle;

[0038] Figure 3 This is a schematic diagram of the structure of the temperature homogenization layer of this utility model;

[0039] Figure 4 This is one of the cross-sectional structural diagrams of the pre-tightening layer of this utility model;

[0040] Figure 5 This is the second schematic diagram of the cross-sectional structure of the pre-tightening layer of this utility model.

[0041] The reference numerals in the attached figures are as follows:

[0042] 1. First high-temperature resistant layer;

[0043] 2. Temperature homogenizing layer; 21. Temperature homogenizing holes;

[0044] 3. Second high-temperature resistant layer;

[0045] 4. Enclosure cavity;

[0046] 5. Pre-tightening layer; 51. Upper silicone strip; 52. Lower silicone strip;

[0047] 6. Elastic sheet. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0049] A specific embodiment provides a composite thermal insulation structure between battery cells. This composite thermal insulation structure includes a first high-temperature resistant layer and a second high-temperature resistant layer made of mica paper sheets, a temperature equalization layer composed of soluble composite cotton sheets inside the clamping cavity, and a pre-tightening layer composed of silicone strips. The first and second high-temperature resistant layers form a thermal barrier by bonding or sewing to inhibit heat transfer. The temperature equalization layer balances the temperature between battery cells through phase change heat storage and capillary temperature equalization mechanisms. The pre-tightening layer composed of upper and lower silicone strips provides directional elastic pre-tightening force to adapt to cell expansion and assembly tolerances. This composite thermal insulation structure between battery cells effectively solves the technical problems of insufficient temperature resistance, uneven temperature uniformity, and poor pre-tightening force in existing battery cell thermal insulation structures. It has the characteristics of adapting to the tolerances of various parts of the battery pack and adapting to the dynamic strain of the battery cells, high reliability, low cost, and lightweight, and is suitable for thermal protection between battery cells in power batteries and energy storage batteries.

[0050] The first implementation of the inter-cell composite thermal insulation structure is as follows: Figure 1 and Figure 2 As shown, the battery pack includes a first high-temperature resistant layer 1, a temperature equalization layer 2, a second high-temperature resistant layer 3, and a pre-tightening layer 5, which are installed inside the battery pack and located between the battery cells. The first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 are bonded or sewn to form a clamping cavity 4. The temperature equalization layer 2 is located inside the clamping cavity 4. The first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 block the heat transmitted between the battery cells, and the temperature equalization layer 2 absorbs the temperature between the battery cells with uniform storage capacity. A pre-tightening layer 5 is provided outside the first high-temperature resistant layer 1 and the second high-temperature resistant layer 3. The pre-tightening layer 5 includes upper and lower parts, which are respectively located at the upper and lower ends of the first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 in the height direction of the battery cells. It is used to provide elastic pre-tightening force between the battery cells and to accommodate the tolerances of various parts in the battery pack.

[0051] As one alternative implementation method

[0052] Regarding the specific structure of the first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 mentioned above, this embodiment is as follows: Figure 1 and Figure 2 As shown, both the first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 are mica paper sheets.

[0053] When applied, the mica paper sheet has a high temperature resistance of 1000 degrees Celsius. Compared with the traditional thermal insulation structure that uses a single polyolefin foam material, this technical solution utilizes the high temperature resistance of the mica paper sheet to avoid the risk of the thermal insulation material softening and deforming when high temperatures occur between the battery cells, and can effectively block heat transfer between the battery cells.

[0054] Among them, the outer sides of the first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 facing the battery cell are both thermal runaway surfaces, and the inner sides facing the clamping cavity 4 or the temperature equalization layer 2 are both cold surfaces. The mica paper can control the temperature of the cold surface to remain below 200 degrees Celsius when the temperature of the thermal runaway surface reaches 600 degrees Celsius.

[0055] Regarding the specific structure of the aforementioned temperature equalization layer 2, this embodiment is as follows: Figure 1 As shown, the temperature equalization layer 2 is a soluble composite cotton sheet.

[0056] Among them, soluble composite cotton sheets can be made of cellulose-based cotton impregnated with phase change materials.

[0057] When applied, the temperature equalization layer 2 can quickly absorb and evenly distribute the heat between the cells through phase change heat absorption and capillary diffusion, and evenly release the energy of the locally overheated area of ​​the cell to the adjacent area, reducing the temperature difference gradient between different areas in the battery pack and avoiding local overheating.

[0058] Regarding the specific structure of the aforementioned pre-tightening layer 5, this embodiment is as follows: Figure 1 As shown, the upper and lower parts of the pre-tightening layer 5 are respectively an upper silicone strip 51 and a lower silicone strip 52 with elasticity.

[0059] When applied, the upper silicone strip 51 and the lower silicone strip 52 are fixed to the outside of the first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 by means of bonding or welding.

[0060] The upper silicone strip 51 and the lower silicone strip 52 provide continuous elastic preload between the cells through their good elasticity and heat resistance. They continuously provide horizontal preload between the cells through elastic deformation, compensating for the gaps required for cell expansion during charging and discharging, as well as the assembly gaps of components inside the battery pack.

[0061] This technical solution's inter-cell composite thermal insulation structure effectively solves the core technical problems of insufficient temperature resistance, uneven temperature distribution, and poor pre-tightening force adaptability in existing inter-cell thermal insulation structures through the synergistic thermal insulation, heat preservation, and elastic pre-tightening of its multi-layer structure. Specifically, its advantages are as follows:

[0062] Enhanced high-temperature resistance and thermal runaway protection: The first high-temperature resistant layer 1 and the second high-temperature resistant layer 3 are combined using mica paper sheets to form an encapsulation cavity 4. This double-layer high-temperature resistant encapsulation cavity 4 structure forms a thermal barrier, which can significantly delay the high-temperature transfer during cell thermal runaway and ensure that the cold surface temperature remains stable below 200℃. Compared with traditional insulation structures using single polyolefin foam materials, the high-temperature resistance of mica paper sheets avoids the risk of softening and deformation of the insulation material when high temperatures occur between cells. It can effectively block heat transfer between cells, improve the overall temperature resistance of the battery pack, and is a technical solution with a cost far lower than the aerogel insulation structure of aerospace materials, combining economy and reliability.

[0063] Optimized temperature uniformity and thermal shock buffering: A soluble composite cotton layer 2 is set between two high-temperature resistant layers. This layer 2 can quickly absorb and evenly distribute the heat between the cells through phase change heat absorption and capillary diffusion, and evenly release the energy of the locally overheated areas of the cells to the adjacent areas, reducing the temperature gradient between areas in the battery pack, avoiding local overheating, and ensuring the temperature uniformity inside the battery pack. This composite thermal insulation structure between cells can reduce the temperature difference between cells, effectively avoid the chain reaction caused by heat accumulation, and at the same time alleviate the dynamic impact of cell expansion on the thermal insulation structure.

[0064] Enhanced elastic preload adaptation and tolerance compatibility: A silicone strip is set as a preload layer 5 on the outside of the high-temperature resistant layer. The upper silicone strip 51 and the lower silicone strip 52 are fixed at both ends of the high-temperature resistant layer, respectively. The upper silicone strip 51 and the lower silicone strip 52 provide continuous elastic preload between the cells through their good elasticity and heat resistance. They continuously provide horizontal preload between the cells through elastic deformation, compensating for the gaps required for cell expansion during charging and discharging, as well as the assembly gaps of components inside the battery pack. They adapt to the tolerances of each component inside the battery pack and the dynamic strain of the cells caused by temperature changes, ensuring the stability and reliability of the structure. Compared with the traditional integral elastic frame insulation structure, the local reinforcement scheme of the upper and lower silicone strips ensures resilience while avoiding the thickness redundancy caused by the material fully wrapping the cells, making it more suitable for compact battery pack designs.

[0065] Simplified process and cost control: During production, the mica paper sheet and the upper and lower silicone strips of the pre-tightening layer can be fixed between layers by bonding or sewing, eliminating the need for complex aerogel coating or light-blocking agent modification processes, thus reducing the number of production steps; the soluble composite cotton sheet can be processed through an integrated impregnation-drying process, significantly reducing manufacturing costs. The composite thermal insulation structure between the battery cells in this technical solution can meet the needs of large-scale production.

[0066] In summary, this composite thermal insulation structure between battery cells exhibits excellent performance in improving the high-temperature resistance, temperature uniformity, and pre-tightening force of the thermal insulation structure between battery cells. It can effectively adapt to the tolerances of various components within the battery pack and the dynamic strain of the battery cells as temperature changes, thereby enhancing the safety and reliability of the battery pack.

[0067] A second embodiment of the inter-cell composite thermal insulation structure is as follows: Figure 3 As shown, the difference between this embodiment and the first embodiment is that, for the structure of the soluble composite cotton sheet, the soluble composite cotton sheet is evenly spread in the clamping cavity 4 and evenly distributed with temperature equalization holes 21.

[0068] When applied, the soluble composite cotton sheet is pressed into a sheet shape and then needle-punched to form uniformly distributed temperature-equalizing holes 21, which facilitates heat transmission and improves the absorption and diffusion performance of the temperature-equalizing layer 2 in terms of heat between the battery cells.

[0069] A third embodiment of the inter-cell composite thermal insulation structure is as follows: Figure 4 As shown, the difference between this embodiment and the first embodiment is that both the upper silicone strip 51 and the lower silicone strip 52 are provided with elastic sheets 6.

[0070] Specifically, such as Figure 5 As shown, the cross-sectional structure of the elastic sheet 6 along its length is wavy.

[0071] When applied, the elastic sheet 6 embedded in the silicone strip can enhance the horizontal preload provided by the preload layer 5 between the cells.

[0072] The fourth embodiment of the composite thermal insulation structure between battery cells differs from the first embodiment in that the elastic sheet 6 is a shape memory metal sheet; when the temperature between the battery cells rises, the cross-sectional shape of the elastic sheet 6 in the length direction gradually changes from a wavy shape to a straight shape.

[0073] When applied, the elastic sheet 6 changes its shape from wavy to straight as the temperature rises, which can reduce the preload between the cells and provide space for the thermal expansion of the cells. This prevents the cells from continuously rising in temperature due to excessive preload at high temperatures, reducing the risk of spontaneous combustion or explosion caused by cell damage, cracking, and leakage of internal materials.

[0074] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. A composite thermal insulation structure between battery cells, characterized in that, It includes a first high-temperature resistant layer, a temperature equalization layer, a second high-temperature resistant layer, and a pre-tightening layer installed inside the battery pack and located between the battery cells; The first high-temperature resistant layer and the second high-temperature resistant layer are bonded or stitched to form a clamping cavity. The temperature equalization layer is disposed in the clamping cavity. The first high-temperature resistant layer and the second high-temperature resistant layer block the heat transmitted between the cells and the temperature equalization layer absorbs the temperature between the cells with uniform storage capacity. The pre-tightening layer is provided outside the first high-temperature resistant layer and outside the second high-temperature resistant layer; The pre-tightening layer includes upper and lower parts, which are respectively disposed at the upper and lower ends of the first high-temperature resistant layer and the second high-temperature resistant layer in the cell height direction, and are used to provide elastic pre-tightening force between the cells and to accommodate the tolerances of each component in the battery pack.

2. The composite thermal insulation structure between battery cells according to claim 1, characterized in that, Both the first high-temperature resistant layer and the second high-temperature resistant layer are mica paper sheets.

3. The composite thermal insulation structure between battery cells according to claim 1, characterized in that, The temperature equalization layer is a soluble composite cotton sheet.

4. The composite thermal insulation structure between battery cells according to claim 3, characterized in that, The soluble composite cotton sheet is evenly spread inside the clamping cavity and has uniformly distributed temperature equalization holes.

5. The composite thermal insulation structure between battery cells according to claim 1, characterized in that, The upper and lower parts of the pre-tightening layer are respectively an upper silicone strip and a lower silicone strip with elasticity.

6. The composite thermal insulation structure between battery cells according to claim 5, characterized in that, The upper silicone strip and the lower silicone strip are fixed to the outside of the first high-temperature resistant layer and the outside of the second high-temperature resistant layer by means of bonding or welding.

7. The composite thermal insulation structure between battery cells according to claim 5, characterized in that, Both the upper and lower silicone strips contain elastic sheets.

8. The composite thermal insulation structure between battery cells according to claim 7, characterized in that, The cross-sectional structure of the elastic sheet along its length is wavy.

9. The composite thermal insulation structure between battery cells according to claim 8, characterized in that, The elastic sheet is a shape memory metal sheet; as the temperature between the battery cells increases, the cross-sectional shape of the elastic sheet in the length direction gradually changes from a wavy shape to a straight shape.

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