Cell heat insulation pad and battery pack

Abstract

The present application relates to the field of energy storage technologies, and discloses a battery cell heat insulation pad and a battery pack. The battery cell heat insulation pad includes a first attachment film layer, a second attachment film layer, and a first core material layer. The first attachment film layer includes a first encapsulation portion and a first peripheral portion surrounding the first encapsulation portion. The second attachment film layer includes a second encapsulation portion and a second peripheral portion surrounding the second encapsulation portion. A receiving cavity is formed between the second encapsulation portion and the first encapsulation portion, and the second peripheral portion is connected to the first peripheral portion. The first core material layer is disposed in the receiving cavity. The first core material layer includes a first heat insulation portion and a second heat insulation portion surrounding the first heat insulation portion. The minimum thickness of the first heat insulation portion is t1, and the maximum thermal conductivity of the first heat insulation portion in the thickness direction is λ1. The thickness of the second heat insulation portion is t2, and the thermal conductivity of the second heat insulation portion in the thickness direction is λ2. The battery cell heat insulation pad and the battery pack provided by the present application can be conducive to improving the heat insulation performance of the battery cell heat insulation pad.

Description

Technical Field

[0001] This application relates to the technical field of energy storage, and particularly relates to a cell heat insulation pad and a battery pack. Background Art

[0002] With the continuous development of energy storage technology, energy storage devices are increasingly widely used. Energy storage devices can store the electric energy output by power generation devices, and at the same time, can output the stored electric energy to electrical equipment. Energy storage devices use cells as the basic units for storing electric energy, and cells can form battery modules through series or parallel connection. Since battery modules generate heat during operation, in order to avoid the concentration of heat affecting the performance of cells, cell heat insulation pads are provided in the battery modules.

[0003] The cell heat insulation pad has the function of preventing heat transfer, which can avoid the mutual influence between different cells, and thus avoid the phenomenon of heat concentration and cascading thermal runaway. The heat insulation performance of the cell heat insulation pad affects the performance of the cells. How to design the structure of the cell heat insulation pad to improve its heat insulation performance is an important issue. Summary of the Invention

[0004] The purpose of the embodiments of this application is to provide a cell heat insulation pad and a battery pack, which can be conducive to improving the heat insulation performance of the cell heat insulation pad.

[0005] To solve the above technical problems, the embodiments of this application provide a cell heat insulation pad. The cell heat insulation pad is used to be attached to the surface of the cell for heat insulation. The cell heat insulation pad includes a first attachment film layer, a second attachment film layer, and a first core material layer. The first attachment film layer includes a first encapsulation part and a first peripheral part surrounding the first encapsulation part. The second attachment film layer includes a second encapsulation part and a second peripheral part surrounding the second encapsulation part. A receiving cavity is formed between the second encapsulation part and the first encapsulation part, and the second peripheral part is connected to the first peripheral part. The first core material layer is disposed in the receiving cavity. The first core material layer includes a first heat insulation part and a second heat insulation part surrounding the first heat insulation part. The minimum thickness of the first heat insulation part is t1, and the maximum thermal conductivity of the first heat insulation part in the thickness direction is λ1. The thickness of the second heat insulation part is t2, and the thermal conductivity of the second heat insulation part in the thickness direction is λ2, and t1 is greater than t2 and / or λ1 is less than λ2.

[0006] The embodiments of this application also provide a battery pack. The battery pack includes a box body, a battery module, and the above-mentioned cell heat insulation pad. The box body has a receiving cavity. The battery module is disposed in the receiving cavity. The battery module includes a plurality of cells arranged in the same direction and two end plates sandwiching the plurality of cells in the middle. The cell heat insulation pad is disposed between two adjacent cells or between the cell and the end plate.

[0007] The battery cell heat insulation pad and the battery pack provided by the embodiments of the present application form a receiving area between the first encapsulation film and the second encapsulation film of the battery cell heat insulation pad, and a first core material layer for heat insulation is placed in the receiving area. The second heat insulation part of the first core material layer surrounds the first heat insulation part located in the middle area. By making the minimum thickness t1 of the first heat insulation part greater than the thickness t2 of the second heat insulation part, or making the maximum thermal conductivity λ1 of the first heat insulation part in the thickness direction less than the thermal conductivity λ2 of the second heat insulation part in the thickness direction, or simultaneously making the minimum thickness t1 of the first heat insulation part greater than the thickness t2 of the second heat insulation part and the maximum thermal conductivity λ1 of the first heat insulation part in the thickness direction less than the thermal conductivity λ2 of the second heat insulation part in the thickness direction, the battery cell heat insulation pad can form a heat insulation characteristic that the heat insulation performance improves from the edge area to the middle area. Thus, it can adapt to the temperature distribution characteristic of the battery cell surface, improve the heat insulation performance of the battery cell heat insulation pad, and reduce the cost.

[0008] In some embodiments, the first heat insulation part includes a first part and a second part surrounding the first part. The edge of the second part far from the first part is connected to the second heat insulation part. The thickness of the first part is ta, the thermal conductivity of the first part in the thickness direction is λa, the thickness of the second part is tb, and the thermal conductivity of the second part in the thickness direction is λb, and ta is greater than tb and / or λa is less than λb. In this way, by forming the first part and the second part with different heat insulation performances, a gradient distribution of heat insulation performance with more than two levels can be formed in the heat insulation core material of the battery cell heat insulation pad, which is beneficial to giving full play to the heat insulation effects in different areas.

[0009] In some embodiments, the ratio between ta and tb is 1.1 to 1.5, and the ratio between tb and t2 is 1.3 to 1.7. In this way, by controlling the ratio of the thicknesses of different parts, the heat insulation effects of different parts can be precisely controlled to adapt to the heat insulation requirements in different areas of the battery cell surface.

[0010] In some embodiments, the area of the first part is S1, the area of the second part is S2, and the area of the second heat insulation part is S3. The ratio between S1 and S2 is 0.11 to 0.20, and the ratio between S2 and S3 is 1.1 to 2.0. In this way, by controlling the areas of different parts of the heat insulation core material, the areas corresponding to different temperature distribution gradients on the battery cell surface can be adapted to the temperatures in different areas of the battery cell surface.

[0011] In some embodiments, the battery cell thermal insulation pad further includes a second core material layer, which is attached to the side of the first core material layer close to the first attachment film layer. The second core material layer includes a third heat insulation portion and a fourth heat insulation portion surrounding the third heat insulation portion. The thickness of the third heat insulation portion is t3, the thermal conductivity of the third heat insulation portion in the thickness direction is λ3, the thickness of the fourth heat insulation portion is t4, and the thermal conductivity of the fourth heat insulation portion in the thickness direction is λ4. t3 is greater than t4 and / or λ3 is less than λ4. In this way, a composite heat insulation core material can be formed by combining the second core material layer and the first core material layer, effectively improving the overall heat insulation performance of the heat insulation core material.

[0012] In some embodiments, the battery cell thermal insulation pad further includes a third core material layer, which is attached to the side of the second core material layer away from the first core material layer. The third core material layer includes a fifth heat insulation portion and a sixth heat insulation portion surrounding the fifth heat insulation portion. The thickness of the fifth heat insulation portion is t5, the thermal conductivity of the fifth heat insulation portion in the thickness direction is λ5, the thickness of the sixth heat insulation portion is t6, and the thermal conductivity of the sixth heat insulation portion in the thickness direction is λ6. t5 is greater than t6 and / or λ5 is less than λ6. In this way, a heat insulation core material with a three-layer sandwich structure can be formed by setting the third core material layer, which is beneficial to forming a heat insulation structure with a relatively uniform change in heat insulation performance from the edge region to the middle region, meeting the heat insulation requirements of the gradually changing temperature on the surface of the battery cell.

[0013] In some embodiments, the projection of the third heat insulation portion towards the first core material layer is located within the edge of the first heat insulation portion, and the projection of the fifth heat insulation portion towards the second core material layer is located within the edge of the third heat insulation portion. In this way, by controlling the distribution area of the heat insulation portions of different core material layers, the change in the heat insulation performance of the sandwich-structured heat insulation core material can be made relatively gentle, while effectively improving the overall heat insulation performance, meeting the heat insulation requirements at different regions on the surface of the battery cell.

[0014] In some embodiments, the battery cell thermal insulation pad further includes a first adhesive layer and a second adhesive layer. The first adhesive layer is attached to the side of the first attachment film layer away from the second attachment film layer, and the second adhesive layer is attached to the side of the second attachment film layer away from the first attachment film layer. A first release paper is provided on the side of the first adhesive layer away from the first attachment film layer, and a second release paper is provided on the side of the second adhesive layer away from the second attachment film layer. In this way, through the setting of the adhesive layers, the battery cell thermal insulation pad can be conveniently bonded to the surface of the battery cell.

[0015] In some embodiments, the battery cell thermal insulation pad further includes a buffer member, which is provided between the first attachment film layer and the first adhesive layer, and the projection of the buffer member on the first attachment film layer surrounds the first encapsulation portion. In this way, through the setting of the buffer member, a buffering effect can be achieved to protect the heat insulation core material.

[0016] In some embodiments, the buffer member is provided with a plurality of through holes, and the plurality of through holes are arranged around the center of the buffer member. In this way, by providing through holes in the buffer member, space can be provided for deformation and contraction, which is beneficial to protecting the heat insulation core material.

[0017] In some embodiments, the buffer member is provided with ribs, and the ribs protrude from the edge of the buffer member in a direction away from the center. In this way, the surface of the battery cell can be effectively insulated by the ribs, and the blue film on the surface of the battery cell can be protected.

[0018] In some embodiments, the first core material layer, the second core material layer and the third core material layer are sewn together into one body by sewing threads. In this way, the structural stability during the lamination of different core material layers can be ensured in the form of sewing.

[0019] In some embodiments, t1 is greater than or equal to 1.5 mm and less than or equal to 5 mm, and λ1 is greater than or equal to 0.01 W / m·K and less than or equal to 0.08 W / m·K. In this way, by controlling the thickness of the first heat insulation part and the maximum thermal conductivity of the first heat insulation part in the thickness direction, it can be ensured that while saving materials, the heat insulation performance of the material itself is fully exerted. Description of the Drawings

[0020] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the drawings in the figures do not constitute a proportional limitation.

[0021] Figure 1 is a schematic perspective view of a battery cell heat insulation pad provided by some embodiments of the present application;

[0022] Figure 2 is an exploded schematic view of a battery cell heat insulation pad provided by some embodiments of the present application;

[0023] Figure 3 is a schematic front view of the first core material layer in a battery cell heat insulation pad provided by some embodiments of the present application;

[0024] Figure 4 is a schematic top view of the first core material layer in a battery cell heat insulation pad provided by some embodiments of the present application;

[0025] Figure 5 is a schematic top view of the first core material layer in a battery cell heat insulation pad provided by other embodiments of the present application;

[0026] Figure 6 is an exploded schematic view of a battery cell heat insulation pad provided by other embodiments of the present application;

[0027] Figure 7 It is a front view structural schematic diagram of the second core material layer in the battery cell heat insulation pad provided by some other embodiments of the present application;

[0028] Figure 8 It is a top view structural schematic diagram of the second core material layer in the battery cell heat insulation pad provided by some other embodiments of the present application;

[0029] Figure 9 It is an exploded structural schematic diagram of the battery cell heat insulation pad provided by some other embodiments of the present application;

[0030] Figure 10 It is a front view structural schematic diagram of the third core material layer in the battery cell heat insulation pad provided by some other embodiments of the present application;

[0031] Figure 11 It is a top view structural schematic diagram of the third core material layer in the battery cell heat insulation pad provided by some other embodiments of the present application;

[0032] Figure 12 It is a separation structural schematic diagram of the heat insulation core material in the battery cell heat insulation pad provided by some other embodiments of the present application;

[0033] Figure 13 It is a three-dimensional structural schematic diagram of the buffer member in the battery cell heat insulation pad provided by some embodiments of the present application;

[0034] Figure 14 It is a stress deformation schematic diagram of a partial position of the buffer member in the battery cell heat insulation pad provided by some embodiments of the present application;

[0035] Figure 15 It is a front view structural schematic diagram of the battery cell in the prior art. Specific Embodiments

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will elaborate on each embodiment of the present application with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in each embodiment of the present application, many technical details are provided for the readers to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions required to be protected by the present application can still be achieved. The division of the following embodiments is for convenience of description and should not constitute any limitation to the specific implementation manners of the present application. The various embodiments can be combined and cross-referenced with each other on the premise of not being contradictory.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "comprising" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0038] In the description of the embodiments of this application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0039] With the continuous development of new energy technologies, the proportion of new energy used in social life and production is also increasing continuously. The application of energy storage devices is also increasing continuously. In actual situations, energy storage devices can adopt the form of cabin-level energy storage, cluster-level energy storage, and pack (battery pack)-level energy storage according to different application scenarios. The battery cell, that is, the single battery, as an efficient energy storage component, is widely used in different types of energy storage devices. Multiple battery cells can form a battery module through series or parallel connection, and the battery module adopts a certain packaging form to form a whole. One or more battery modules can be used in an energy storage device, and a certain number of battery modules can form a battery cluster for unified management and control. Multiple battery modules can be encapsulated in a box of a certain volume to form a battery pack, or can be encapsulated in a larger container to form a container energy storage system. Multiple battery modules can be jointly managed and controlled through a battery management system and a thermal management system.

[0040] During the charge and discharge process of the battery cell, chemical reactions occur inside, generating a large amount of heat energy, which causes the temperature of the battery module to rise. Especially as the capacity of the battery cell becomes larger and the energy density becomes higher, the heat generated during the operation of the battery cell is also increasing continuously. To ensure that heat does not concentrate due to heat transfer between battery cells, a battery cell heat insulation pad is usually provided on the surface of the battery cells in the battery module to prevent the heat diffusion process of the battery cells. The battery cell heat insulation pad contains a heat insulation core material made of a material with a low thermal conductivity, which has good heat insulation effect and flame retardant performance at the same time. The battery cell heat insulation pad can be provided between two adjacent battery cells in the middle position, or on the surface of the battery cell in the outermost position facing the box body, to isolate the heat transfer path from the battery cell to the surrounding area. And, when thermal runaway occurs in some battery cells, the battery cell heat insulation pad can play a flame retardant role to prevent the thermal runaway of the battery cell from spreading and causing a chain thermal runaway of other battery cells.

[0041] However, currently, the battery cell heat insulation pad usually arranges a heat insulation core material with the same thickness and the same material on the entire surface, and it is necessary to design the thickness of the heat insulation core material according to the maximum temperature, which easily results in high material costs. And, the heat insulation core material is not designed according to the heat generation characteristics of the battery cell itself, resulting in poor heat insulation efficiency and low material utilization rate of the battery cell heat insulation pad.

[0042] To improve the heat insulation performance of the battery cell heat insulation pad, some embodiments of the present application provide a battery cell heat insulation pad. According to the characteristic that there is a temperature gradient distribution in the heat generation of the battery cell itself, that is, the temperature gradually changes from the middle area to the edge area, the heat insulation core material is optimized to make the heat insulation performance of the battery cell heat insulation pad present a gradient distribution. Thus, a gradient heat insulation performance is formed for the battery cell heat insulation pad, enhancing the thermal safety and improving the heat insulation efficiency. It can make the battery cell heat insulation pad more adaptable to complex working conditions and improve the service life of the product. The gradient arrangement of the heat insulation performance of the battery cell heat insulation pad can give full play to the characteristics and advantages of the material and reduce costs.

[0043] It should be noted that when the battery module is working, the temperature at the middle area on the surface of the battery cell is the highest and gradually spreads outwards, showing a temperature gradient that gradually decreases from the middle area to the edge area. And, there is a certain gap in the temperature distribution between different areas, forming a middle area with a higher temperature and an edge area with a lower temperature. There is also a phenomenon of gradual temperature change in some areas. By setting a heat insulation core material with variable thickness or variable material, or a heat insulation core material with both thickness and material changing in the battery cell heat insulation pad, the battery cell heat insulation pad can form a heat insulation characteristic presenting a gradient distribution corresponding to the temperature characteristic of the gradient distribution on the surface of the battery cell. The heat insulation performance of the heat insulation core material shows an increasing form from the edge area to the middle area, which can give full play to the heat insulation performance of different areas of the heat insulation core material while meeting the heat insulation requirements.

[0044] The following combines with Figures 1 to 14The structure of the battery cell thermal insulation pad provided in some embodiments of the present application is described. The battery cell thermal insulation pad is used to be attached to the surface of the battery cell for thermal insulation.

[0045] like Figures 1 to 14 As shown, the battery cell thermal insulation pad provided in some embodiments of the present application includes a first attachment film layer 11, a second attachment film layer 12 and a first core material layer 13. The first attachment film layer 11 includes a first packaging portion 111 and a first peripheral portion 112 surrounding the first packaging portion 111. The second attachment film layer 12 includes a second packaging portion 121 and a second peripheral portion 122 surrounding the second packaging portion 121. A receiving cavity is formed between the second packaging portion 121 and the first packaging portion 111, and the second peripheral portion 122 is connected to the first peripheral portion 112. The first core material layer 13 is arranged in the receiving cavity. The first core material layer 13 includes a first thermal insulation portion 131 and a second thermal insulation portion 132 surrounding the first thermal insulation portion 131. The minimum thickness of the first thermal insulation portion 131 is t1, and the maximum thermal conductivity of the first thermal insulation portion 131 in the thickness direction is λ1. The thickness of the second heat insulating portion 132 is t2 , the thermal conductivity of the second heat insulating portion 132 in the thickness direction is λ2 , t1 is greater than t2 and / or λ1 is less than λ2 .

[0046] The adhesive film layer is the outer packaging portion of the battery cell's thermal insulation pad. The adhesive film layer can be fixedly connected to the surface of the battery cell. For example, it can be fixed to the surface of the battery cell by adhesive bonding, partial adhesive bonding, magnetic attraction, or strapping. The adhesive film layer includes a first adhesive film layer 11 and a second adhesive film layer 12, which are arranged opposite each other. A cavity is formed between the two adhesive film layers to accommodate the thermal insulation core material, which can be used to encapsulate the thermal insulation core material. The encapsulation portion of each adhesive film layer corresponds to the encapsulation area of the thermal insulation core material, and the peripheral portion corresponds to the connection area between the two adhesive film layers. The peripheral portions of the two adhesive film layers can be formed into a single body by heat pressing, bonding, or sewing. For example, the adhesive film layer can be made of hot melt film to facilitate hot pressing and forming a single body. The hot melt film can be provided with a recessed cavity. Different hot melt films are hot pressed and combined around the edges, leaving a burr. After pressing, the thermal insulation core material is encapsulated internally, and the thermal insulation core material is tightly and completely adhered to the surface of the hot melt film.

[0047] The first core material layer 13 forms the heat-insulating core material of the battery cell heat-insulating pad and is made of a material with a relatively low thermal conductivity, which can better isolate the heat transfer and block the heat transfer path. The first core material layer 13 includes different heat-insulating parts, and different heat-insulating parts can be made of the same heat-insulating material with different thicknesses, or made of different heat-insulating materials with the same thickness, or made of heat-insulating materials with different thicknesses and different materials, so as to form different heat-insulating characteristics in different areas of the battery cell heat-insulating pad. Since the thermal resistance is proportional to the thickness and inversely proportional to the thermal conductivity, by making the minimum thickness t1 of the first heat-insulating part 131 greater than the thickness t2 of the second heat-insulating part 132, and / or the maximum thermal conductivity λ1 of the first heat-insulating part 131 in the thickness direction less than the thermal conductivity λ2 of the second heat-insulating part 132 in the thickness direction, the heat-insulating performance of the first heat-insulating part 131 in the middle area can be higher than that of the second heat-insulating part 132 in the edge area, so as to meet the heat-insulating requirements of areas with different temperature gradients on the surface of the battery cell. The thermal conductivity refers to the amount of heat transferred through an area of 1 square meter in 1 second under stable heat transfer conditions, with a temperature difference of 1 degree between the two surfaces of a material with a thickness of 1 meter. The thermal conductivity can be used to characterize the heat conduction performance and reflect the heat-insulating characteristics. The unit of thermal conductivity is W / m·K, that is, watt per meter degree.

[0048] The first heat-insulating part 131 is located in the middle area of the first core material layer 13 and contacts the middle area of the surface of the battery cell. The second heat-insulating part 132 is located in the edge area of the first core material layer 13 and contacts the edge area of the surface of the battery cell. The middle area is the area formed by spreading a certain range outward from the center point, and the edge area is the other area outside the central area that surrounds the central area. Different heat-insulating parts of the first core material layer 13 can play a heat-insulating effect corresponding to different areas on the surface of the battery cell. In actual situations, the first core material layer 13 and the battery cell heat-insulating pad can have outer contours of different shapes. If the first core material layer 13 and the battery cell heat-insulating pad have a rectangular outer contour, the center point of the first core material layer 13 is located at the intersection of the two diagonals. If the first core material layer 13 and the battery cell heat-insulating pad are circular structures, the center point of the first core material layer 13 is located at the center of the circle. If the first core material layer 13 and the battery cell heat-insulating pad are irregularly shaped, the center point position can be determined according to the shape center of the first core material layer 13. In addition, the outer contour shape of the first core material layer 13 and the outer contour shape of the battery cell heat-insulating pad can be kept consistent or set in different forms.

[0049] For the cell heat insulation pad provided by some embodiments of the present application, a receiving area is formed between the first encapsulation film and the second encapsulation film, and the first core material layer 13 that plays a heat insulation role is placed in the receiving area. The second heat insulation portion 132 of the first core material layer 13 surrounds the first heat insulation portion 131 located in the middle area. By making the minimum thickness t1 of the first heat insulation portion 131 greater than the thickness t2 of the second heat insulation portion 132, or making the maximum thermal conductivity λ1 of the first heat insulation portion 131 in the thickness direction less than the thermal conductivity λ2 of the second heat insulation portion 132 in the thickness direction, or simultaneously making the minimum thickness t1 of the first heat insulation portion 131 greater than the thickness t2 of the second heat insulation portion 132 and the maximum thermal conductivity λ1 of the first heat insulation portion 131 in the thickness direction less than the thermal conductivity λ2 of the second heat insulation portion 132 in the thickness direction, the cell heat insulation pad can form a heat insulation characteristic that improves from the edge area to the middle area. Thus, it can adapt to the temperature distribution characteristic of the cell surface, improve the heat insulation performance of the cell heat insulation pad, and reduce costs.

[0050] In some embodiments, the first heat insulation portion 131 may include a first part 1311 and a second part 1312 surrounding the first part 1311. The edge of the second part 1312 far from the first part 1311 is connected to the second heat insulation portion 132. The thickness of the first part 1311 is ta, the thermal conductivity of the first part 1311 in the thickness direction is λa, the thickness of the second part 1312 is tb, the thermal conductivity of the second part 1312 in the thickness direction is λb, and ta is greater than tb and / or λa is less than λb.

[0051] The first part 1311 is located in the middle area of the first heat insulation part 131, and the second part 1312 is located in the edge area of the first heat insulation part 131. The second part 1312 is connected to the second heat insulation part 132. That is to say, the first core material layer 13 can be arranged from the middle area to the edge area to form a gradient distribution characteristic of the heat insulation performance at three levels. The first part 1311 and the second part 1312 are located in different areas of the first heat insulation part 131 of the first core material layer 13. The first part 1311, the second part 1312 and the second heat insulation part 132 form a heat insulation characteristic of a three-level gradient distribution. The thickness ta of the first part 1311 is greater than the thickness tb of the second part 1312, or the thermal conductivity λa of the first part 1311 in the thickness direction is less than the thermal conductivity λb of the second part 131 in the thickness direction, or the thickness ta of the first part 1311 is greater than the thickness tb of the second part 1312 and the thermal conductivity λa of the first part 1311 in the thickness direction is less than the thermal conductivity λb of the second part 1312 in the thickness direction, so that the heat insulation performance of the first part 1311 is higher than that of the second part 1312. As a result, the first core material layer 13 forms a gradient distribution characteristic of the heat insulation performance exceeding two levels from the middle area to the edge area, making the heat insulation performance of the first core material layer 13 more refined and more corresponding to the distribution characteristic of the temperature decreasing from the middle area to the edge area on the surface of the battery cell. Moreover, it can better adapt to the gradually changing temperature distribution characteristic on the surface of the battery cell, making the correspondence between the heat insulation performance at different areas of the battery cell heat insulation pad and the temperature characteristics at different areas on the surface of the battery cell closer. When the surface area of the battery cell is large, the heat insulation requirements at different areas on the surface of the battery cell can be met by forming a gradient distribution of the heat insulation performance exceeding two levels.

[0052] In some embodiments, the heat-insulating core material is designed with different thicknesses. The heat-insulating core material is selected as aerogel and is coated inside the accommodation cavity formed by encapsulation with a hot-melt film. The upper hot-melt film and the lower hot-melt film are made of PET (Polyethylene Terephthalate), and the two are thermocompression bonded around the periphery with flash edges left. After bonding, the heat-insulating core material is coated inside, and the heat-insulating core material closely and completely adheres to the surface of the hot-melt film. The heat-insulating core material can be composed of three types of aerogels with different thicknesses, and the thicknesses of the three types of aerogels decrease in sequence from the middle area to the edge area of the heat-insulating core material. The heat-insulating core material is integrally set as a rectangle, and different heat-insulating parts are divided according to rectangles respectively. According to the gradient characteristics of the heat generation temperature of the battery cell, the dimensional relationships among the thicknesses, lengths, and widths of the three types of aerogels are designed. L1, L2, and L3 are the boundary length dimensions of the first part 1311, the second part 1312, and the second heat-insulating part 132 respectively, with the unit of mm (millimeter); W1, W2, and W3 are the boundary width dimensions of the first part 1311, the second part 1312, and the second heat-insulating part 132 respectively, with the unit of mm. The dimensional relationships among the thicknesses, lengths, and widths of the three types of aerogels can be: ta:tb:t2 = 4:3:2; L1:L2:L3 = 3:8:10; W1:W2:W3 = 2:6:7. Figure 15 The surface structure of the battery cell is schematically shown, and the surface dimensions of the battery cell are as Figure 15 shown, where Lc is the length dimension of the battery cell surface and Wc is the width dimension of the battery cell surface. According to the gradient characteristics of the heat generation temperature of the battery cell, the range of the thickness ta of the first part 1311 of the heat-insulating core material is taken as 1.5 mm to 5 mm; the range of the boundary length dimension L3 of the second heat-insulating part 132 is taken as 0.92Lc to 0.95Lc; the range of the boundary width dimension W3 of the second heat-insulating part 132 is taken as 0.9Wc to 0.97Wc.

[0053] In addition, when there are parts with different thicknesses in the heat-insulating core material, in order to ensure the same degree of adhesion in different areas when adhering to the battery cell, the attaching film layer can be set as an inward concave arc structure. That is, the attaching film layer can have different thickness distribution characteristics from the heat-insulating core material to ensure the consistency of the thickness of each part of the battery cell heat-insulating pad. And, the outer side of the attaching film layer can also have a certain curvature to adapt to the expansion and deformation of the battery cell, reduce the extrusion force acting on the heat-insulating core material, and improve the service life of the heat-insulating core material.

[0054] In some other embodiments, the heat-insulating core material is formed of three different materials. The heat-insulating materials in different regions are respectively selected as nano heat-insulating pads, aerogels, and ceramic silica gel foams. The three heat-insulating materials are arranged in such a way that the thermal conductivity in the thickness direction decreases successively from the edge region to the middle region. According to the gradient distribution characteristics of the temperature of the battery cell during heat generation, the thickness dimensions of the three heat-insulating materials can be obtained through experiments based on the thermal conductivity of different materials. The thicknesses of the three heat-insulating materials can decrease successively from the middle region to the edge region of the heat-insulating core material, or remain the same. The minimum value of the thermal conductivity ranges from 0.01 W / m·K to 0.08 W / m·K.

[0055] In actual situations, a gradient distribution characteristic of heat-insulating performance with more than three levels can also be formed in the first core material layer 13 from the middle region to the edge region to adapt to the heat distribution characteristics on the surface of the battery cell. The gradient distribution characteristic of the heat-insulating performance of the first core material layer 13 from the middle region to the edge region can also be controlled within three levels to save the cost of the battery cell heat-insulating pad. Additionally, lug portions can be formed around the battery cell heat-insulating pad. A plurality of lug portions are provided, and the plurality of lug portions are arranged around the center of the heat-insulating core material. Thus, a protruding structure with spaced arrangement is formed on the periphery of the battery cell heat-insulating pad. Each lug portion can be set into different tooth-shaped structures, such as a triangular or rectangular protruding shape, or a trapezoidal protruding shape. It can save the use of heat-insulating materials in the edge region while being in contact with the edge region of the battery cell surface. And a distribution characteristic can be formed in which the area of the heat-insulating material in the edge region is smaller than the area of the heat-insulating material in the middle region, adapting to the heat-insulating requirements in different regions of the battery cell surface. At the same time, the space between the lug portions can also reserve space for the expansion of the battery cell surface, adapting to the expansion and deformation of the battery cell and reducing the extrusion force on the battery cell heat-insulating pad.

[0056] As Figure 5 shown, rounded corners can be left at the joints of different parts of the heat-insulating core material to eliminate sudden changes in thermal stress, and the thermal performance gradient change is closer to the heat generation characteristics of the battery cell. The radius of the rounded corner at the joint between the first part 1311 and the second part 1312 can be controlled within the range of 2 mm to 8 mm, such as 2 mm, 4 mm, 6 mm, or 8 mm. The radius of the rounded corner at the joint between the second part 1312 and the second heat-insulating part 132 can be controlled within the range of 10 mm to 30 mm, such as 10 mm, 13 mm, 16 mm, 19 mm, 20 mm, 23 mm, 26 mm, 29 mm, or 30 mm.

[0057] In addition, the ratio between the thickness ta of the first part 1311 and the thickness tb of the second part 1312 can be 1.1 to 1.5, and the ratio between the thickness tb of the second part 1312 and the thickness t2 of the second heat-insulating part 132 is 1.3 to 1.7.

[0058] By controlling the thickness of different parts, the heat insulation performance of different parts can be optimized. The thermal resistance of the heat insulation core material is proportional to the thickness, and the thickness of different parts of the heat insulation core material shows a gradually increasing trend from the edge region to the middle region. The thickness ta of the first part 1311 located in the middle region is greater than the thickness tb of the second part 1312 located in the middle transition region, and the thickness of the second part 1312 located in the middle transition region is greater than the thickness t2 of the second heat insulation part 132 located in the edge region.

[0059] The ratio between the thickness ta of the first part 1311 and the thickness tb of the second part 1312 can be controlled within the range of 1.1 to 1.5, such as 1.1, 1.2, 1.3, 1.4 or 1.5. The ratio between the thickness tb of the second part 1312 and the thickness t2 of the second heat insulation part 132 can be controlled within the range of 1.3 to 1.7, such as 1.3, 1.4, 1.5, 1.6 or 1.7. By controlling the thickness ratio between different parts of the first core layer 13, it is possible to avoid the situation where the heat insulation characteristics of the materials in different regions of the first core layer 13 cannot be fully utilized due to a large difference in thickness, and it is also possible to avoid the situation where it is unable to better meet the heat insulation requirements of different regions on the surface of the battery cell due to a small difference in thickness.

[0060] In some embodiments, the area of the first part 1311 is S1, the area of the second part 1312 is S2, and the area of the second heat insulation part 132 is S3. The ratio between the area S1 of the first part 1311 and the area S2 of the second part 1312 is 0.11 to 0.20, and the ratio between the area S2 of the second part 1312 and the area S3 of the second heat insulation part 132 is 1.1 to 2.0.

[0061] Different regions of the first core layer 13 correspond to different regions on the surface of the battery cell. By controlling the area of different regions of the first core layer 13, the coverage area of different regions on the first core layer 13 corresponding to the corresponding regions on the surface of the battery cell can be controlled. So that the regions with different heat insulation performances of the battery cell heat insulation pad are fitted to the regions with different temperatures on the surface of the battery cell. Controlling the area of the first part 1311 to be smaller than the area of the second part 1312 can give full play to the heat insulation performance of the heat insulation material of the first part 1311, making the first part 1311 face the middle region with a higher temperature on the surface of the battery cell. Controlling the area of the second part 1312 to be larger than the area of the second heat insulation part 132 can make the middle transition region of the heat insulation core material form a sufficient area, which can effectively block the heat transfer path on the surface of the battery cell. Controlling the area of the second heat insulation part 132 can make the edge region of the heat insulation core material form a smaller area, which can reduce the use of heat insulation materials in the edge region while achieving a certain heat insulation effect.

[0062] In actual situations, the ratio between the area S1 of the first part 1311 and the area S2 of the second part 1312 is within the range of 0.11 to 0.20, such as 0.11, 0.13, 0.15, 0.17, 0.19 or 0.20. The ratio between the area S2 of the second part 1312 and the area S3 of the second heat insulation part 132 is within the range of 1.1 to 2.0, such as 1.1, 1.3, 1.5, 1.7, 1.9 or 2.0.

[0063] As Figure 6 shown, the battery cell heat insulation pad may further include a second core material layer 14, and the second core material layer 14 is attached to the side of the first core material layer 13 close to the first attachment film layer 11. The second core material layer 14 includes a third heat insulation part 141 and a fourth heat insulation part 142 surrounding the third heat insulation part 141. The thickness of the third heat insulation part 141 is t3, the thermal conductivity of the third heat insulation part 141 in the thickness direction is λ3, the thickness of the fourth heat insulation part 142 is t4, and the thermal conductivity of the fourth heat insulation part 142 in the thickness direction is λ4, where t3 is greater than t4 and / or λ3 is less than λ4.

[0064] The second core material layer 14 and the first core material layer 13 are also made of materials with relatively low thermal conductivity. The second core material layer 14 can be attached to the first core material layer 13 to form a composite heat insulation structure, so as to enhance the heat insulation performance of the core material layer. The second core material layer 14 includes multiple parts with different thicknesses and / or different thermal conductivities in the thickness direction, so as to form different heat insulation performances in different regions of the second core material layer 14. The third heat insulation part 141 is located in the middle area of the second core material layer 14, and the fourth heat insulation part 142 is located in the edge area of the second core material layer 14. By making the thickness t3 of the third heat insulation part 141 greater than the thickness t4 of the fourth heat insulation part 142, or making the thermal conductivity λ3 of the third heat insulation part 141 in the thickness direction less than the thermal conductivity λ4 of the fourth heat insulation part 142 in the thickness direction, or making the thickness t3 of the third heat insulation part 141 greater than the thickness t4 of the fourth heat insulation part 142 and the thermal conductivity λ3 of the third heat insulation part 141 in the thickness direction less than the thermal conductivity λ4 of the fourth heat insulation part 142 in the thickness direction, the heat insulation performance at the middle area of the second core material layer 14 can be improved. Thus, the heat insulation effect at the middle area of the battery cell heat insulation pad is strengthened, and the transfer of heat between different battery cells is effectively blocked.

[0065] As Figure 9As shown, the battery cell thermal insulation pad may further include a third core material layer 15, which is attached to the side of the second core material layer 14 away from the first core material layer 13. The third core material layer 15 includes a fifth thermal insulation portion 151 and a sixth thermal insulation portion 152 surrounding the fifth thermal insulation portion 151. The thickness of the fifth thermal insulation portion 151 is t5, and the thermal conductivity of the fifth thermal insulation portion 151 in the thickness direction is λ5. The thickness of the sixth thermal insulation portion 152 is t6, and the thermal conductivity of the sixth thermal insulation portion 152 in the thickness direction is λ6. t5 is greater than t6 and / or λ5 is less than λ6.

[0066] The third core material layer 15 and the first core material layer 13 are attached to both sides of the second core material layer 14, sandwiching the second core material layer 14 in the middle to form a three-layer sandwich structure. This can effectively improve the thermal insulation effect of the battery cell thermal insulation pad. The third core material layer 15 includes multiple parts with different thicknesses and / or different thermal conductivity coefficients in the thickness direction, thereby forming differentiated thermal insulation performance in different areas of the third core material layer 15. The fifth thermal insulation part 151 is located in the middle area of the third core material layer 15, and the sixth thermal insulation part 152 is located in the edge area of the third core material layer 15. By making the thickness t5 of the fifth thermal insulation portion 151 greater than the thickness t6 of the sixth thermal insulation portion 152, or making the thermal conductivity λ5 of the fifth thermal insulation portion 151 in the thickness direction less than the thermal conductivity λ6 of the sixth thermal insulation portion 152 in the thickness direction, or making the thickness t5 of the fifth thermal insulation portion 151 greater than the thickness t6 of the sixth thermal insulation portion 152 and the thermal conductivity λ5 of the fifth thermal insulation portion 151 in the thickness direction less than the thermal conductivity λ6 of the sixth thermal insulation portion 152 in the thickness direction, the thermal insulation performance in the middle area of the third core material layer 15 can be improved. This strengthens the thermal insulation effect in the middle area of the battery cell thermal insulation pad and effectively blocks heat transfer between different battery cells.

[0067] In actual situations, the composite thermal insulation core material can be composed of at least three or more core material layers, and the composite thermal insulation core material is staggered and stacked in at least three layers. The dimensions of the thickness, length, and width of the composite thermal insulation core material can be obtained through experimental design. In order to achieve gradient-distributed thermal insulation performance of the multi-layer composite thermal insulation core material, the thermal conductivity of each core material layer can be designed to form a multi-level gradient distribution from the middle area to the edge area. The multi-layer thermal insulation core material presents a multi-layer sandwich structure and is arranged inside the accommodating cavity formed by the attached film layer. The attached film layer can be hot-pressed and combined to leave burrs around it. After pressing, the composite thermal insulation core material is wrapped inside, and the thermal insulation core material is tightly and completely attached to the surface of the attached film layer.

[0068] In some embodiments, the projection of the third insulation part 141 toward the first core material layer 13 may be located within the edge of the first insulation part 131 , and the projection of the fifth insulation part 151 toward the second core material layer 14 may be located within the edge of the third insulation part 141 .

[0069] Different core material layers can be provided with different heat insulation parts in a gradient form, that is, the boundary lines of the different heat insulation parts of multiple core material layers gradually move away from or gradually approach the central position. Thereby, the change trend of the overall heat insulation performance of the battery cell heat insulation pad from the edge area to the middle area becomes more uniform, so as to meet the heat insulation requirements of the gradually changing surface temperature of the battery cell. The core material layer with a larger area in the middle area can face the battery cell surface with a higher maximum temperature, and the core material layer with a smaller area in the middle area can face the battery cell surface with a lower maximum temperature.

[0070] In actual situations, the third core material layer 15 can also have the same gradient distribution characteristic of heat insulation performance as the first core material layer 13, that is, the distribution of the different heat insulation parts of the third core material layer 15 and the first core material layer 13 has a mirror image relationship on both sides of the second core material layer 14, presenting as symmetrically attached to both sides of the second core material layer 14. To ensure the heat insulation requirements between two battery cells with similar temperatures.

[0071] As Figure 9 shown, the battery cell heat insulation pad can further include a first adhesive layer 16 and a second adhesive layer 17. The first adhesive layer 16 is attached to the side of the first attachment film layer 11 away from the second attachment film layer 12, and the second adhesive layer 17 is attached to the side of the second attachment film layer 12 away from the first attachment film layer 11. A first release paper 161 is provided on the side of the first adhesive layer 16 away from the first attachment film layer 11, and a second release paper 171 is provided on the side of the second adhesive layer 17 away from the second attachment film layer 12.

[0072] That is to say, the battery cell heat insulation pad is provided with an adhesive layer for pasting and a release paper for protecting the adhesive layer on the outer side of the attachment film layer. The battery cell heat insulation pad can be pasted on the battery surface through the adhesive layer. In actual situations, only by tearing off the outermost release paper of the battery cell heat insulation pad can the bonding between the battery cell heat insulation pad and the battery cell surface be achieved through the adhesive layer. The release paper is provided with an easy-to-tear part protruding outside the adhesive layer, that is, a tear tab. Through the easy-to-tear part, it is convenient to tear off the release papers on both sides of the battery cell heat insulation pad to expose the adhesive layer. Furthermore, it can be bonded to the battery cell surface through the adhesive layer.

[0073] As Figure 9 shown, the battery cell heat insulation pad can further include a buffer member 18. The buffer member 18 is arranged between the first attachment film layer 11 and the first adhesive layer 16, and the projection of the buffer member 18 on the first attachment film layer 11 surrounds the first encapsulation part 111.

[0074] The buffer member 18 has a deformation characteristic and can play a buffering role in the battery cell heat insulation pad. The buffer member 18 can be made of natural rubber, synthetic rubber or foaming material. For example, the buffer member 18 can be a foam.

[0075] The buffer member 18 can be a buffer frame or a buffer strip. The buffer strip can be placed around the heat insulation core material. The buffer strip can rebound under a certain pressure and has good flame retardant performance. It can be used to absorb the expansion force generated during the charging and discharging of the battery cell, playing a role in protecting the battery cell. At the same time, the buffer member 18 can also protect the heat insulation core material to prevent the heat insulation core material from being damaged by the extrusion of the battery cell. The use of the buffer member 18 is beneficial to reducing the thickness of the heat insulation core material and avoiding the need to use a relatively thick heat insulation core material to achieve the buffer effect, which is beneficial to cost reduction.

[0076] In actual situations, the buffer member 18 can be only arranged on both sides of the heat insulation core material. While ensuring the buffer effect, it can reduce the influence on the heat insulation area of the heat insulation core material and increase the effective area of the heat insulation core material, making the heat insulation and flame retardant area of the battery cell heat insulation pad larger and effectively delaying the time of thermal runaway of the battery cell.

[0077] When the buffer member 18 is set as a loop frame, it can also limit the position of the heat insulation core material, making the heat insulation core material firmly held in the accommodation cavity and not being extruded outside the loop frame due to the expansion of the battery cell, ensuring the normal use of the heat insulation core material. The loop frame can be made of silicone material, and the corner positions can be set in a chamfered form. The buffer foam with a loop frame structure can be attached to the hot melt film pressing flash edge. The adhesive layer on the outside of the hot melt film selects double-sided adhesive and is respectively attached to the upper and lower hot melt films. The release paper tape on the outside of the adhesive layer has tear tabs, and the tear tabs are symmetrically arranged for easy operation by automated equipment.

[0078] In some embodiments, the buffer member 18 can be provided with a plurality of through holes 181, and the plurality of through holes 181 are arranged around the center of the buffer member 18.

[0079] The through holes 181 can be sequentially arranged along the extension direction of the buffer member 18, and the through holes 181 are distributed at different parts of the buffer member 18. The setting of the through holes 181 can provide space for the deformation and contraction of the buffer member 18, which is beneficial to the deformation and contraction of the local position of the buffer member 18 and ensures the overall buffer effect of the buffer member 18.

[0080] As Figure 13 shown, the buffer member 18 is set as a loop frame structure, and pores are formed at different parts of the loop frame. As Figure 14 shown, following the principle of minimum resistance, the buffer member 18 contracts and deforms towards the center of the hole during the process of being compressed by force, playing a role in avoiding extrusion of the heat insulation core material.

[0081] In addition, the buffer member 18 can be provided with rib strips 182, and the rib strips 182 protrude from the edge of the buffer member 18 in a direction away from the center.

[0082] The rib 182 can be disposed at one side edge or both side edges of the buffer member 18, or at the four peripheral edges of the buffer member 18. The rib 182 extends the isolation area of the buffer member 18 and can effectively isolate the surface of the battery cell. By adding rib features at the edge of the buffer member 18, the surface of the battery cell can be effectively isolated, the blue film on the surface of the battery cell can be protected, and the blue film can be prevented from being damaged.

[0083] In some embodiments, the first core material layer 13, the second core material layer 14 and the third core material layer 15 can be sewn together into one body by knitting threads.

[0084] That is to say, for the heat insulation core material composed of different core material layers, after combination, a mesh structure can be knitted. It can make the combined heat insulation core material not easily break along the splicing joint due to the restraint of the knitting structure, improve the overall stiffness and strength of the battery cell heat insulation pad, and ensure the stability of the heat insulation effect of the battery cell heat insulation pad. The knitting threads can be sewn to form a mesh knitting structure.

[0085] In some embodiments, the minimum thickness t1 of the first heat insulation part 131 is greater than or equal to 1.5 mm and less than or equal to 5 mm, and the maximum thermal conductivity λ1 of the first heat insulation part 131 in the thickness direction is greater than or equal to 0.01 W / m·K and less than or equal to 0.08 W / m·K.

[0086] The thickness of the first heat insulation part 131 affects the heat insulation performance of the middle area of the first core material layer 13. By controlling the thickness of the first heat insulation part 131, it can be avoided that the middle area of the first core material layer 13 cannot achieve a high heat insulation effect due to too small thickness. At the same time, it can also be avoided that the middle area of the first core material layer 13 wastes materials due to too large thickness, which is not conducive to giving full play to the heat insulation performance of the materials. The minimum thickness t1 of the first heat insulation part 131 can be controlled within the range of 1.5 mm to 5 mm, such as 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm.

[0087] The maximum thermal conductivity λ1 of the first heat insulation part 131 in the thickness direction also affects the heat insulation performance of the middle area of the first core material layer 13. By controlling the maximum thermal conductivity λ1 of the first heat insulation part 131 in the thickness direction, it can be avoided that the material cost is increased due to too small thermal conductivity in the middle area of the first core material layer 13. At the same time, it can also be avoided that the middle area of the first core material layer 13 cannot achieve a good heat insulation effect due to too large thermal conductivity. The maximum thermal conductivity λ1 of the first heat insulation part 131 in the thickness direction can be controlled within the range of 0.01 W / m·K to 0.08 W / m·K, such as 0.01 W / m·K, 0.02 W / m·K, 0.04 W / m·K, 0.06 W / m·K or 0.08 W / m·K.

[0088] In actual situations, the heat-insulating core material can be heat-insulating materials such as aerogel, nano heat-insulating pad, ceramic silica gel foam, mica, MPP (Microcellular Polypropylene), silica gel, etc. The hot-melt film material can be film materials such as PET, PC (Polycarbonate), etc. The buffer foam can be silica gel, ceramic silica gel foam, MPP, rubber, etc. The adhesive layer is generally adhesives such as 3M adhesive, pressure-sensitive adhesive, etc. The combination method between various materials is adhesive bonding, hot pressing, etc.

[0089] The aerogel heat-insulating core material has a low thermal conductivity and good flame retardancy, and can effectively block the chain reaction caused by the thermal runaway of the battery cell. When the battery cell undergoes thermal runaway, the temperature on the surface of the battery cell rises, and the heat-insulating core material can delay the transfer of heat to other battery cells, thereby effectively preventing heat spread. That is, the battery cell heat-insulating pad can effectively prevent heat from transferring from the battery cell with thermal runaway to the battery cells without thermal runaway. When the battery cell with thermal runaway catches fire, the battery cell heat-insulating pad can also isolate the burning battery cell from the battery cells without thermal runaway, thereby avoiding the spread of thermal runaway among stacked battery cells.

[0090] In addition, aerogel has an extremely high porosity, specific surface area, excellent chemical stability and flame retardancy, and is light in weight. It can play a good flame retardant role and is beneficial to achieving lightweight.

[0091] Different attachment film layers can be pre-made into a packaging bag structure, and after loading the heat-insulating core material, it is heat-pressed and sealed, which can improve the packaging efficiency of the heat-insulating core material and make the battery cell heat-insulating pad more stable, and can meet the customization requirements in different situations. Different attachment film layers can also be pre-clamped on both sides of the heat-insulating core material, and a concave accommodating area is formed on at least one packaging adhesive film to position the heat-insulating core material. Then the attachment film layers are heat-pressed and fixed. Different attachment film layers can also be formed by bending the same film layer. The same film layer is folded in half to form two relatively arranged attachment film layers, and the heat-insulating core material is sandwiched in the middle. Then the other edges outside the folded edge are heat-pressed and fixed to complete the fixation of the heat-insulating core material.

[0092] The material of the attachment film layer can be a polymer, including but not limited to PET film, PI (Polyimide) film, PVC (Polyvinylchlorid) film, PP (Polypropylene) film. It has a low thermal conductivity and can improve the heat-insulating effect of the entire battery cell heat-insulating pad. At the same time, the self-adhesiveness of the attachment film layer can ensure the wrapping effect on the heat-insulating core material, making the structure of the battery cell heat-insulating pad stable, with low cost and light weight, which is beneficial to achieving the lightweight of the battery module.

[0093] Some embodiments of the present application further provide a battery pack, which includes a box body, a battery module, and the above-mentioned battery cell heat insulation pad. The box body has a receiving cavity. The battery module is disposed in the receiving cavity. The battery module includes a plurality of battery cells arranged in the same direction, and two end plates that sandwich the plurality of battery cells in the middle. The battery cell heat insulation pad is disposed between two adjacent battery cells or between a battery cell and an end plate.

[0094] When the battery cell heat insulation pad is disposed between two adjacent battery cells, it can play a heat insulation role between the two adjacent battery cells, avoiding the rapid spread of heat from a certain out-of-control battery cell to other battery cells when a certain battery cell undergoes thermal runaway, thereby improving the use safety of the battery pack. At the same time, it can also prevent electrical contact between two adjacent battery cells from causing a short circuit phenomenon, thereby ensuring the use reliability of the battery pack. When the battery cell heat insulation pad is located between the edge battery cell and the end plate, it can play a heat insulation role between the battery cell and the inner wall of the box body, avoiding the heat generated by the battery cell from being directly transferred to the box body, resulting in too fast temperature rise inside the battery pack. The difference in the heat insulation performance of different regions of the battery cell heat insulation pad ensures the heat insulation effect on different regions of the battery cell surface, which is more conducive to improving the use safety of the battery pack.

[0095] In addition, the projection of the battery cell heat insulation pad on the surface of the battery cell is located within the edge of the battery cell surface. The length of the surface of the battery cell facing the battery cell heat insulation pad is Lc, the width of the surface of the battery cell facing the battery cell heat insulation pad is Wc, the length of the first core material layer 13 of the battery cell heat insulation pad is L1, and the width of the first core material layer 13 of the battery cell heat insulation pad is W1. L1 is greater than or equal to 0.92Lc and less than or equal to 0.95Lc, and W1 is greater than or equal to 0.9Wc and less than or equal to 0.97Wc.

[0096] By making the size of the heat insulation core material of the battery cell heat insulation pad close to the size of the battery cell surface, it can ensure that the battery cell heat insulation pad can play a good heat insulation role on the entire battery cell surface. At the same time, it can better exert the heat insulation performance of the heat insulation material and avoid material waste.

[0097] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present application. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A battery cell heat insulation pad, which is used to be attached to the surface of the battery cell for heat insulation, and is characterized in that The cell heat insulation pad includes: A first adhering film layer, including a first encapsulation part and a first peripheral part surrounding the first encapsulation part; A second adhering film layer, including a second encapsulation part and a second peripheral part surrounding the second encapsulation part. A receiving cavity is formed between the second encapsulation part and the first encapsulation part, and the second peripheral part is connected to the first peripheral part; A first core material layer, disposed in the receiving cavity. The first core material layer includes a first heat insulation part and a second heat insulation part surrounding the first heat insulation part. The minimum thickness of the first heat insulation part is t1, the maximum thermal conductivity of the first heat insulation part in the thickness direction is λ1, the thickness of the second heat insulation part is t2, the thermal conductivity of the second heat insulation part in the thickness direction is λ2, and t1 is greater than t2 and / or λ1 is less than λ2; It further includes a second core material layer, which is attached to the side of the first core material layer close to the first adhering film layer. The second core material layer includes a third heat insulation part and a fourth heat insulation part surrounding the third heat insulation part. The thickness of the third heat insulation part is t3, the thermal conductivity of the third heat insulation part in the thickness direction is λ3, the thickness of the fourth heat insulation part is t4, the thermal conductivity of the fourth heat insulation part in the thickness direction is λ4, and t3 is greater than t4 and / or λ3 is less than λ4.

2. The cell heat insulation pad according to claim 1, wherein The first heat insulation part includes a first part and a second part surrounding the first part. The edge of the second part far from the first part is connected to the second heat insulation part. The thickness of the first part is ta, the thermal conductivity of the first part in the thickness direction is λa, the thickness of the second part is tb, the thermal conductivity of the second part in the thickness direction is λb, and ta is greater than tb and / or λa is less than λb.

3. The cell heat insulation pad according to claim 2, wherein The ratio between ta and tb is 1.1 to 1.5, and the ratio between tb and t2 is 1.3 to 1.

7.

4. The cell heat insulation pad according to claim 3, wherein The area of the first part is S1, the area of the second part is S2, and the area of the second heat insulation part is S3. The ratio between S1 and S2 is 0.11 to 0.20, and the ratio between S2 and S3 is 1.1 to 2.

0.

5. The cell heat insulation pad according to claim 1, wherein, It further includes a third core material layer, which is attached to the side of the second core material layer far from the first core material layer. The third core material layer includes a fifth heat insulation part and a sixth heat insulation part surrounding the fifth heat insulation part. The thickness of the fifth heat insulation part is t5, the thermal conductivity of the fifth heat insulation part in the thickness direction is λ5, the thickness of the sixth heat insulation part is t6, the thermal conductivity of the sixth heat insulation part in the thickness direction is λ6, and t5 is greater than t6 and / or λ5 is less than λ6.

6. The cell heat insulation pad according to claim 5, characterized in that, The projection of the third heat insulation part towards the first core material layer is located within the edge of the first heat insulation part, and the projection of the fifth heat insulation part towards the second core material layer is located within the edge of the third heat insulation part.

7. The cell heat insulation pad according to any one of claims 1 to 6, wherein It further includes a first adhesive layer and a second adhesive layer. The first adhesive layer is attached to the side of the first attachment film layer away from the second attachment film layer. The second adhesive layer is attached to the side of the second attachment film layer away from the first attachment film layer. A first release paper is provided on the side of the first adhesive layer away from the first attachment film layer, and a second release paper is provided on the side of the second adhesive layer away from the second attachment film layer.

8. The cell heat insulation pad according to claim 7, characterized in that, It further includes a buffer member. The buffer member is disposed between the first attachment film layer and the first adhesive layer, and the projection of the buffer member on the first attachment film layer surrounds the first encapsulation portion.

9. The cell heat insulation pad according to claim 8, wherein The buffer member is provided with a plurality of through holes, and the plurality of through holes are arranged around the center of the buffer member.

10. The cell heat insulation pad according to claim 8, wherein, The buffer member is provided with ribs, and the ribs protrude from the edge of the buffer member in a direction away from the center.

11. The cell heat insulation pad according to claim 5 or 6, characterized in that, The first core material layer, the second core material layer and the third core material layer are stitched together by a thread.

12. The cell heat insulation pad according to claim 1, wherein, The t1 is greater than or equal to 1.5 mm and less than or equal to 5 mm, and the λ1 is greater than or equal to 0.01 W / m·K and less than or equal to 0.08 W / m·K.

13. A battery pack, characterized in that, Comprising: A box body having a receiving cavity; A battery module disposed in the receiving cavity. The battery module includes a plurality of battery cells arranged in the same direction, and two end plates sandwiching the plurality of battery cells in the middle. The battery cell heat insulation pad according to any one of claims 1 to 12 is disposed between two adjacent battery cells or between the battery cell and the end plate.

14. The battery pack according to claim 13, wherein Comprising: The projection of the battery cell heat insulation pad on the surface of the battery cell is located within the edge of the surface of the battery cell. The length of the surface of the battery cell facing the battery cell heat insulation pad is Lc, the width of the surface of the battery cell facing the battery cell heat insulation pad is Wc, the length of the first core material layer of the battery cell heat insulation pad is L1, and the width of the first core material layer of the battery cell heat insulation pad is W1. The L1 is greater than or equal to 0.92Lc and less than or equal to 0.95Lc, and the W1 is greater than or equal to 0.9Wc and less than or equal to 0.97Wc.

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