A battery pack and battery bag

Abstract

This utility model belongs to the field of battery technology and discloses a battery pack and battery assembly. The battery pack includes individual battery cells and a heating element. Multiple battery cells are arranged sequentially with gaps between adjacent cells. The heating element extends along the arrangement direction of the multiple battery cells and is attached to at least one surface of each battery cell. The surface has a first side near the terminal post of the battery cell and a second side away from the terminal post. The heating element has multiple weak points, each with lower tensile strength than the rest of the heating element, and at least partially overlaps with the gaps. The distance between adjacent weak points is D1 mm, the distance from the weak point to the first side is D2 mm, and the product of D1 and D2 is s (in mm). 2 , 200≤s≤2200.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery pack and battery module. Background Technology

[0002] Lithium-ion battery packs are widely used in electric vehicles and energy storage systems due to their high energy density and long cycle life. The performance and safety of lithium-ion batteries are highly dependent on operating temperature, especially at low temperatures where charge / discharge efficiency, capacity, and power output decrease significantly. To ensure normal operation of the battery at low temperatures, heating structures, such as heating films, are typically integrated onto or inside the battery pack to heat it to a preset operating temperature range.

[0003] Currently, common heating films are typically bonded to the surface of individual battery cells or modules. While this design effectively improves battery performance at low temperatures, the tight adhesion between the heating film and the battery surface restricts normal battery expansion during charging and discharging. Lithium-ion batteries undergo volume changes during cycling, especially after high-rate charging and discharging or long-term use, where the expansion and contraction of electrode materials become more pronounced. If the heating film is too rigid or the adhesion is too strong, it may hinder normal battery expansion, leading to internal stress accumulation, which can cause problems such as battery interface delamination, increased local pressure, and even accelerate battery aging or cause mechanical damage.

[0004] More seriously, this restricted expansion may further increase the risk of thermal runaway. When the battery temperature rises sharply due to overheating or an internal short circuit, its internal gas production and expansion behavior become more intense. If the heating film restricts the battery's expansion space, the internal pressure may not be released in time, causing heat and gas to accumulate locally, thereby accelerating the spread of thermal runaway and even triggering safety accidents such as fires or explosions. Utility Model Content

[0005] The purpose of this invention is to provide a battery pack and battery stack that can heat the battery pack to its operating temperature range while maintaining its low-temperature performance, and further reduce the risk of thermal runaway caused by the limited expansion of battery volume.

[0006] To achieve this objective, the present invention adopts the following technical solution: A battery pack, comprising: A battery cell, wherein multiple battery cells are arranged sequentially, with gaps between adjacent battery cells; A heating element extends along the arrangement direction of the plurality of battery cells and is attached to at least one surface of the battery cells, the surface having a first side close to the terminal post of the battery cell and a second side away from the terminal post of the battery cell; the heating element is provided with a plurality of weak portions, the weak portions at least partially overlapping the gap; Wherein, the distance between adjacent weak points is D1mm, the distance between the weak point and the edge of the heating element near the first side is D2mm, and the product of D1 and D2 is s, in mm. 2 , 200≤s≤2200.

[0007] Battery pack, including: Box; and, In the above scheme, multiple battery packs are installed inside the housing.

[0008] Beneficial effects: In the first aspect of this invention, by providing a heating element, the battery pack can be maintained within its normal operating temperature range, ensuring its low-temperature performance. Simultaneously, by forming multiple weak points on the heating element, with each weak point having a lower tensile strength than the heating element substrate, the tensile force required for the heating element to deform is reduced. This ensures that when a battery cell expands, the weak points weaken or even eliminate the overall restriction of the heating element on the battery cell's expansion. This effectively avoids thermal runaway of the battery pack caused by the added heating element restricting the normal expansion of the battery cell. Furthermore, since the weak points at least partially overlap with the gaps, the minimum distance D2mm between two adjacent weak points will not be too large, at least close to the thickness of a battery cell. Additionally, since the weak points on the heating element also affect its heating performance, the minimum distance D2mm between two adjacent weak points will not be too small, meaning the weak points will not be too densely packed. D1mm is limited by the width of the heating element itself, so D1mm will not be too large, and to ensure the weak points function properly, D1mm will not be too small. Therefore, s should also not be too large, as an excessively large s would restrict the normal expansion of the battery. However, 's' should not be too small, as an excessively small 's' will weaken the structural strength of the heating element, leading to tearing and damage. By limiting 's' to 200 ≤ 2200, the overall structure of the heating element is optimized. This ensures that the heating element's effect on limiting the normal expansion of the battery cells is weakened or eliminated, while simultaneously ensuring that the structural strength of the heating element itself meets the requirements, thereby guaranteeing the stability of the heating element's performance.

[0009] In a second aspect of this invention, the battery pack based on this battery pack can be rapidly heated to the operating temperature range and maintain low-temperature performance, and can also reduce the risk of thermal runaway caused by limited volume expansion. Attached Figure Description

[0010] Figure 1 This is a first structural schematic diagram of the battery pack provided in an embodiment of the present utility model; Figure 2 This is a schematic diagram of the dimensions of the battery pack provided in an embodiment of this utility model; Figure 3 This is a schematic diagram of the second structure of the battery pack provided in an embodiment of the present invention.

[0011] In the picture: 1. Battery cell; 11. Gap; 12. Surface; 121. First side; 122. Second side; 13. Terminal post; 2. Heating element; 21. Weak part. Detailed Implementation

[0012] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0013] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0014] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0015] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0016] To facilitate understanding of this application, the relevant terms and features will be explained below.

[0017] A battery pack is a modular unit formed by combining multiple individual battery cells in series, parallel, or series-parallel connections. For example, multiple cylindrical or square cells are welded together with metal connecting pieces and encapsulated in a metal or plastic frame to form a physical module with uniform voltage and capacity.

[0018] A battery pack comprises multiple battery cells, a Battery Management System (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (casing, brackets, etc.), and protective parts. These components are housed within a casing and sealed with a cover, forming a complete functional unit capable of directly outputting electrical energy. As a rechargeable battery, the battery pack is the power source for new energy vehicles.

[0019] The battery pack casing is usually divided into upper and lower parts, which are sealed together.

[0020] The battery pack includes at least two battery packs, a BMS control unit, and a housing.

[0021] Please see the appendix Figure 1 and attached Figure 2 The first aspect of this embodiment relates to a battery pack, which includes battery cells 1 and a heating element 2. A plurality of battery cells 1 are arranged sequentially, with a gap 11 between adjacent battery cells 1.

[0022] Specifically, each battery cell 1 is rectangular in shape and is stacked sequentially. Multiple battery cells 1 can be electrically connected through series and / or parallel connections. Adjacent battery cells 1 can also be connected by connectors; for example, double-sided adhesive can be used to bond adjacent battery cells 1 together. A gap 11 exists between adjacent battery cells 1.

[0023] The gap 11 between battery cells 1 is a very critical parameter in battery system design. Its role is not limited to physical isolation, but also directly affects the battery's safety, thermal management efficiency, structural stability and lifespan.

[0024] Specifically, gap 11 provides a flow channel for air or cooling media (such as silicone oil or ethylene glycol aqueous solution), accelerating heat dissipation from the battery surface. Increasing gap 11 can significantly reduce the battery pack's peak temperature and maximum temperature difference (e.g., increasing gap 11 from 1mm to 5mm can reduce the peak temperature of the battery pack by more than 15%), avoiding localized overheating and thermal runaway. Gap 11 prevents direct contact between battery cells 1, avoiding short circuits caused by friction between the battery cell casings or electrode contact due to vibration, compression, or other factors. As a physical insulating zone, gap 11 can delay heat transfer during thermal runaway of battery cells 1, providing response time for safety systems (such as fuse protection). Furthermore, lithium-ion batteries undergo volume expansion during charging and discharging (lithium iron phosphate has an expansion rate of approximately 3%-5%). A reserved gap 11 (e.g., 2mm~6mm) can absorb expansion deformation, preventing structural deformation or cracking caused by mutual compression of the battery casings, thus avoiding severe thermal runaway accidents. Nevertheless, the gap 11 between battery cells 1 cannot be too large. An excessively large gap 11 will inevitably lead to a decrease in the volume utilization rate of the battery pack. Therefore, the size of the gap 11 needs to be optimized from the two dimensions of safety and energy density.

[0025] Heating element 2 can be a heating film. A heating film is a thin-film electrothermal element attached to the outside of the battery pack. It converts electrical energy into heat energy to actively regulate the temperature of individual battery cells 1. It is mainly used to address the performance degradation problem of lithium batteries in low-temperature environments (such as capacity reduction and decreased charging efficiency), and also has thermal runaway isolation functions. It is one of the core components of the thermal management system for new energy vehicle batteries.

[0026] For example, lithium iron phosphate (LiFePO4) batteries, used in new energy vehicles, are widely used in new energy vehicles, energy storage, and communications due to their advantages such as high safety, long cycle life, and low cost. However, their poor low-temperature performance remains a major drawback. This is because at low temperatures, the fluidity of the electrolyte deteriorates, and the resistance to lithium-ion migration increases significantly; the lithium intercalation rate of the graphite anode decreases at low temperatures, and Li... + The desolvation process increases energy consumption and makes it easy for metallic lithium to be deposited on the surface; some electrolyte components may crystallize at extremely low temperatures, blocking ion channels.

[0027] Heating films typically employ a multi-layered composite design, comprising a heating layer, a thermally conductive layer, an insulating layer, a flame-retardant and heat-insulating layer, and auxiliary components. The heating substrate in the heating layer can be metal foil (aluminum / copper foil), alloy wire (iron-chromium-aluminum), or PTC (positive temperature coefficient) material (such as a carbon black / graphite hybrid polymer matrix). The heating substrate generates Joule heat when energized, and the PTC material possesses self-limiting temperature characteristics (resistance increases with temperature, automatically reducing power). The thermally conductive layer is attached to the surface of the battery cell 1 and typically uses a high thermal conductivity aluminum plate (0.25mm) or nickel sheet (0.3mm). The insulating layer is usually made of polyimide, silicone-modified acrylate, or silicone, providing high electrical isolation and insulation. The flame-retardant and heat-insulating layer is usually located between the two heating layers to block abnormal heat diffusion, delay heat spread, and improve unilateral heating efficiency. Auxiliary components typically include terminals (such as RV1.25-6 type wire interfaces with a current carrying capacity of ≤19A), temperature sensors (such as NTC thermistors or thermocouples), and adhesive backing.

[0028] When the heating film is in operation, heat is generated due to the resistive heating effect when current flows through the conductive material of the heating layer. This heat is uniformly transferred to the surface of the battery cell 1 through the heat-conducting layer, raising the temperature of the battery cell 1 and thereby improving electrolyte flow and ion transport rate. For example, at -20°C, the heating film can restore the effective capacity of the battery cell 1 from 70% to over 90%, reducing range degradation by 30%. It also avoids low-temperature lithium plating, reduces irreversible capacity loss, and improves cycle life by 20%-30%.

[0029] In this embodiment, the heating element 2 extends along the arrangement direction of the plurality of battery cells 1 and is attached to at least one surface 12 of the battery cell 1. The surface 12 has a first side 121 close to the terminal post 13 of the battery cell 1 and a second side 122 away from the terminal post 13 of the battery cell 1. The heating element 2 is provided with a plurality of weak portions 21, which at least partially overlap with the gap 11. The minimum distance between adjacent weak portions 21 is D1 mm, the minimum distance between a weak portion 21 and the first side 121 is D2 mm, and the product of D1 and D2 is s, in mm. 2 , 200≤s≤2200.

[0030] Specifically, each of the two sides along the arrangement direction of the battery cells 1 has a surface 12, and the two surfaces 12 are arranged opposite to each other according to the shape characteristics of the battery cells 1. The surfaces 12 have a first side 121 and a second side 122 in the height direction of the battery cells 1. The first side 121 is relatively closer to the terminal post 13 and the second side 122 is relatively farther away from the terminal post 13.

[0031] In this embodiment, the heating element 2 keeps the battery pack within its normal operating temperature range, ensuring its low-temperature performance. Simultaneously, multiple weak points 21 are formed on the heating element 2, spaced apart along the arrangement direction of the battery cells 1. These weak points 21 are more prone to deformation than the heating element 2 substrate, requiring less tensile force for deformation. This ensures that when the battery cells 1 expand, the weak points 21 weaken or even eliminate the overall restriction of the heating element 2 on the expansion of the battery cells 1. This effectively avoids thermal runaway of the battery pack caused by the restriction of normal expansion of the battery cells 1 due to the addition of the heating element 2.

[0032] Furthermore, since the weak portion 21 at least partially overlaps with the gap 11, the minimum spacing D2mm between two adjacent weak portions 21 will not be too large, and will at least be close to the thickness of the battery cell 1. Additionally, since the weak portion 21 on the heating element 2 also affects the heating performance of the heating element 2, the minimum spacing D2mm between two adjacent weak portions 21 will not be too small, meaning the weak portions 21 will not be too densely packed. Typically, 5mm ≤ D2mm ≤ 20mm, and the value of D2mm can be 5mm, 6mm, 7.5mm, 9mm, 10mm, 11.5mm, 12mm, 16mm, 18mm, or 20mm. The value can be one of the aforementioned values ​​or any value between 5mm and 20mm. The minimum spacing D1mm is limited by the width of the heating element 2 itself, so the spacing D1mm will not be too large. And to ensure the weak portion 21 functions properly, the spacing D1mm will not be too small either. Typically, 40mm ≤ D1mm ≤ 110mm, where D1mm can be 40mm, 45mm, 50mm, 80mm, 90mm, 95mm, 100mm, 105mm, or 110mm. These values ​​can be specific to the aforementioned range or any value between 40mm and 110mm. Therefore, the overall value of s will not be too large, as an excessively large s would restrict the normal expansion of the battery. Conversely, the overall value of s should not be too small, as an excessively small s would weaken the structural strength of the heating element 2, leading to tearing and damage. By limiting the reasonable values ​​of D1mm and D2mm, and specifying 200 ≤ s ≤ 2200, the overall structure of the heating element 2 is optimized. This ensures that the limiting effect of the heating element 2 on the normal expansion of the battery cell 1 is weakened or eliminated, while simultaneously ensuring that the structural strength of the heating element 2 meets the requirements, thereby guaranteeing the stable performance of the heating element 2.

[0033] Optionally, the weak part 21 is set to correspond one-to-one with the gap 11.

[0034] Since the multiple gaps 11 between the battery cells 1 are basically evenly distributed, the multiple weak parts 21 of the heating element 2 in this embodiment are arranged at equal intervals and are set in a one-to-one correspondence with the gaps 11, so as to ensure the workability and consistency of the heating element 2.

[0035] Optionally, the weak part 21 is a through hole that extends through the thickness of the heating body 2.

[0036] Specifically, the weak point 21 is an elongated through hole, with a single through hole extending along the height direction of the battery cell 1, or multiple through holes distributed at intervals along the height direction of the battery cell 1.

[0037] In this embodiment, by providing a through-hole that directly penetrates the heating element 2, and with the through-hole partially overlapping the gap 11, the thermal resistance caused by the insulating layer, adhesive, and other media of the heating element 2 can be reduced, allowing heat to be quickly transferred to the battery surface through the through-hole. Compared to a traditional non-perforated heating element 2, the thermal resistance is reduced by more than 40%, and the thermal response time is shortened by 30%–50%. In addition, the through-hole can be precisely aligned with the heat dissipation channel at the gap 11, efficiently dissipating heat and preventing localized overheating due to heat accumulation. At the same time, the heating element 2 is more prone to deformation near the through-hole, thereby preventing the normal expansion of the battery cell 1 from being restricted and reducing the probability of thermal runaway.

[0038] Furthermore, the through-hole can be rectangular, elliptical, or waist-shaped.

[0039] In this embodiment, the cross-section of the through hole can be rectangular, formed by four straight sides. The junction of adjacent straight sides can be smoothly transitioned by rounded corners to reduce the formation of weak points at the junctions, thus preventing stress concentration during the expansion of the battery cell 1 and exacerbating the tearing of the heating element 2. Of course, the through hole can also be elliptical or oblong. The major axis of the ellipse extends in the same direction as the gap 11, thereby avoiding stress concentration at the through hole.

[0040] Optionally, the distance between the through hole and the first side 121 is less than the distance between the through hole and the second side 122.

[0041] In this embodiment, the first side 121 is close to the electrode post 13. During charging and discharging, current is transmitted through the electrode post 13, and this area is prone to concentrated heat due to the resistance effect. Therefore, heat accumulates near the first side 121. By placing the through hole close to the first side 121, heat can be dissipated from the electrode post 13 to the outside, thus preventing heat from accumulating in this area.

[0042] In another embodiment, the weak point 21 is a groove for reducing the thickness of the heating element 2. Specifically, it can be a single groove extending along the height direction of the battery cell 1, or multiple grooves spaced apart along the height direction of the battery cell 1. That is, multiple grooves are provided on the heating element 2, and the grooves are located on the side away from the battery cell 1. The presence of the grooves reduces the thickness of the heating element 2 at this location. By forming grooves, the heating element 2 can be more easily deformed near the grooves, thereby avoiding the restriction of normal expansion of the battery cell 1 and reducing the probability of thermal runaway.

[0043] In this embodiment, there are several ways to arrange two adjacent weak points 21. They can be arranged parallel to each other along the arrangement direction, or they can be staggered, with one close to the first side 121 and the other close to the second side 122, forming a wave-like structure. Alternatively, along the arrangement direction of the battery cells 1, there is at least one pair of weak points 21, with one close to the first side 121 and the other close to the second side 122. Those skilled in the art can easily and flexibly adjust the arrangement of the weak points 21 according to the ease of processing, the strength of the bond, and the impact on the expansion of the battery cells 1. This embodiment does not impose specific limitations on this arrangement.

[0044] Optionally, the heating element 2 and the battery cell 1 are bonded together by an adhesive layer with a thickness of Hmm, where 0.6mm≤Hmm≤2mm.

[0045] In this embodiment, the adhesive layer thickness Hmm should meet the bonding strength required to form a stable connection between the heating element 2 and the battery cell 1. Therefore, the adhesive layer thickness Hmm cannot be too small, as an excessively thin adhesive layer can easily cause the heating element 2 to detach from the battery cell 1, thereby reducing the heating effect or even causing the heating function to fail. Of course, the adhesive layer thickness Hmm also cannot be too large. An excessively large adhesive layer thickness Hmm not only affects heat transfer, leading to a decrease in heating efficiency, but also increases the tensile strength of the heating element 2 due to the increased thickness, thereby restricting the normal expansion of the battery cell 1 and increasing the probability of thermal runaway. In this embodiment, 0.6mm ≤ Hmm ≤ 2mm, and the value of Hmm can be 0.6mm, 0.7mm, 0.85mm, 0.9mm, 1.2mm, 1.5mm, 1.7mm, 1.9mm, or 2mm. The value can be one of the aforementioned values ​​or any value between 0.6mm and 2mm.

[0046] Optionally, the length of the weak part 21 along the direction from the first side 121 to the second side 122 is d1mm, and the length of the heating body 2 along the direction from the first side 121 to the second side 122 is D3mm, wherein 40mm≤d1mm≤60mm, 50mm≤D3mm≤110mm, and 0.4≤d1 / D3≤0.9.

[0047] In this embodiment, the weak part 21 has a length d1mm along the direction from the first side 121 to the second side 122. d1mm cannot be too large, as an excessively large d1mm can easily weaken the structural strength of the heating element 2, making it prone to tearing or damage when the battery cell 1 expands. Conversely, d1mm cannot be too small, as an excessively small d1mm cannot address the problem of limited normal expansion of the battery cell 1. In this embodiment, 40mm ≤ d1mm ≤ 60mm, and the value of d1mm can be 40mm, 41mm, 43mm, 44.5mm, 45mm, 50mm, 55mm, 57.5mm, or 60mm. The value can be one of the aforementioned values ​​or any value between 40mm and 60mm. The length of the heating element 2 along the direction from the first side 121 to the second side 122 is actually the width of the heating element 2, which is D3mm. In this embodiment, 50mm ≤ D3mm ≤ 110mm, where D3mm can be 50mm, 55mm, 70mm, 80mm, 85mm, 90mm, 100mm, 105.5mm, or 110mm. The values ​​can be any of the aforementioned listed values ​​or any value between 50mm and 110mm. In this embodiment, D3mm is smaller than the height of the battery cell 1, and to avoid limiting the expansion of the battery cell 1, D3mm is even much smaller than the height of the battery cell 1. Here, d1 / D3 is the proportion of the weak portion 21 in the width direction of the heating element 2. d1 / D3 should not be too small, as a small proportion will not alleviate the limitation on the expansion of the battery cell 1; nor should d1 / D3 be too large, as a large proportion will result in low strength of the heating element 2 itself, increasing the difficulty of the bonding process of the heating element 2. By taking reasonable values ​​for d1mm and D3mm and limiting it to 0.4≤d1 / D3≤0.9, the expansion requirements of the battery cell 1 can be met, while also satisfying the strength requirements of the heating element 2 itself.

[0048] Optionally, the distance between the weak part 21 and the first side 121 is D4mm, and the distance between the weak part 21 and the second side 122 is D5mm, where 0.3≤D4 / D5≤4.

[0049] In this embodiment, the distance D4mm between the weak portion 21 and the first side 121 is 15mm ≤ D4mm ≤ 40mm. The value of D4mm can be 15mm, 18mm, 20mm, 25mm, 28.5mm, 30mm, 35mm, 37mm, or 40mm. The value can be one of the aforementioned values ​​or any value between 15mm and 40mm. The distance D5mm between the weak portion 21 and the second side 122 is 5mm, 5mm ≤ D5mm ≤ 40mm. The value of D5mm can be 5mm, 8mm, 15mm, 20mm, 27.5mm, 30mm, 35mm, 37mm, or 40mm. The value can be one of the aforementioned values ​​or any value between 5mm and 40mm. The length of the weak portion 21 can be adaptively adjusted according to the battery cell 1, and the width of the heating element 2 can also be adaptively adjusted. By appropriately selecting values ​​for D4mm and D5mm, and limiting it to 0.3≤D4 / D5≤4, we can meet the requirements for the connection strength of the heating element 2 itself, while also ensuring the expansion and deformation requirements of the battery cell 1.

[0050] Optionally, two heating elements 2 are provided, and the two heating elements 2 are respectively attached to two opposite surfaces 12 of the battery cell 1.

[0051] Specifically, two heating elements 2 are respectively attached to the two opposite surfaces 12 of the battery cell 1 along the arrangement direction of the battery cell 1.

[0052] By adopting a dual-sided heating method, heating efficiency can be improved, ensuring the heating rate of battery cell 1, and also making the heating of different parts of battery cell 1 more consistent, thereby improving the performance of the battery pack.

[0053] Furthermore, the weakest parts 21 of the two heating elements 2 are arranged opposite each other.

[0054] The corresponding weak points 21 on the two heating elements 2 have the same shape and size and are arranged opposite each other, so that the temperature field on both sides of the battery cell 1 can be symmetrically distributed, and the temperature rise of different parts of the battery cell 1 is highly consistent. Of course, the weak points 21 of the two heating elements 2 can also be staggered in the arrangement direction of the battery cells 1 (as shown in the attached figure). Figure 3 Alternatively, the heating element 2 may be misaligned in the direction from the first side 121 to the second side 122. This misalignment allows the heating element 2 to be assembled without the need for alignment, thus reducing the assembly difficulty to some extent.

[0055] Those skilled in the art can select or adjust the arrangement of the weak parts 21 on the two heating elements 2 according to factors such as processability, manufacturing cost, and heating conditions. This embodiment does not impose specific limitations.

[0056] The second aspect of this embodiment also relates to a battery pack, which includes a housing and a plurality of battery packs, wherein the plurality of battery packs are installed in the housing.

[0057] The battery pack enclosure serves as the mechanical shell and protective structure of the battery pack. Its primary function is to house the battery pack and other subsystems, providing physical protection, sealing, and heat dissipation channels. The enclosure can withstand impacts, compression, punctures, and other external forces to prevent damage to internal components. It also ensures the entire battery pack achieves an IP67 or higher protection rating (dustproof, immersion in 1 meter of water for 30 minutes), preventing moisture and dust intrusion. Simultaneously, it provides mounting locations for internal heat dissipation air ducts or liquid cooling pipes and supports heat exchange. Furthermore, it separates high-voltage components with insulating materials to avoid short-circuit risks. The enclosure mainly consists of a top cover (fiberglass) and a lower tray (cast aluminum / steel plate).

[0058] In this embodiment, the battery pack based on this battery pack can quickly heat up to the operating temperature range and maintain low-temperature performance, which can also reduce the risk of thermal runaway caused by limited volume expansion.

[0059] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A battery pack characterized by comprising: include: A battery cell (1), a plurality of battery cells (1) are arranged in sequence, and there is a gap (11) between adjacent battery cells (1). A heating element (2) extends along the arrangement direction of the plurality of battery cells (1) and is attached to at least one surface (12) of the battery cell (1). The surface (12) has a first side (121) close to the terminal post (13) of the battery cell (1) and a second side (122) away from the terminal post (13) of the battery cell (1). The heating element (2) is provided with a plurality of weak parts (21), and the weak parts (21) at least partially overlap with the gap (11). Wherein, the distance between adjacent weak parts (21) is D1 mm, the distance between the weak part (21) and the edge of the heating body (2) close to the first side (121) is D2 mm, the product of D1 and D2 is s, unit: mm 2 , 200≤s≤2200.

2. The battery pack of claim 1, wherein, The length of the weak part (21) along the direction from the first side (121) to the second side (122) is d1mm, and the length of the heating body (2) along the direction from the first side (121) to the second side (122) is D3mm, 0.4≤d1 / D3≤0.

9.

3. The battery pack of claim 1, wherein, The distance between the weak part (21) and the first side (121) is D4mm, and the distance between the weak part (21) and the second side (122) is D5mm, 0.3≤D4 / D5≤4.

4. The battery pack according to claim 1, characterized in that, Multiple weak points (21) are spaced apart along the arrangement direction of the battery cells (1).

5. The battery pack according to claim 1, characterized in that, There are two heating elements (2), which are respectively attached to two opposite surfaces (12) of the battery cell (1).

6. The battery pack according to claim 5, characterized in that, The weak points (21) of the two heating elements (2) are arranged opposite each other.

7. The battery pack according to claim 5, characterized in that, The weak points (21) of the two heating elements (2) are misaligned in the direction of the battery cells (1), and / or, It is offset in the direction from the first side (121) to the second side (122).

8. The battery pack according to claim 4, characterized in that, The weak part (21) and the gap (11) are provided in a one-to-one correspondence.

9. The battery pack according to claim 1, characterized in that, The two adjacent weak parts (21) are staggered.

10. The battery pack according to claim 1, characterized in that, Along the arrangement direction of the battery cells (1), at least two adjacent weak points (21) are staggered.

11. The battery pack according to any one of claims 1-10, characterized in that, The weak part (21) is a through hole extending along the height direction of the battery cell (1) and penetrating along the thickness direction of the heating element (2), or a plurality of through holes spaced apart along the height direction of the battery cell (1).

12. The battery pack according to claim 11, characterized in that, The distance between the through hole and the first side (121) is less than the distance between the through hole and the second side (122).

13. The battery pack according to claim 11, characterized in that, The through hole can be rectangular, elliptical, or oblong.

14. The battery pack according to any one of claims 1-10, characterized in that, The weak part (21) is a groove extending along the height direction of the battery cell (1) and used to reduce the thickness of the heating element (2), or a plurality of grooves distributed at intervals along the height direction of the battery cell (1) for reducing the thickness of the heating element (2).

15. The battery pack according to any one of claims 1-10, characterized in that, The heating element (2) is bonded to the battery cell (1) through an adhesive layer with a thickness of Hmm, where 0.6mm≤Hmm≤2mm.

16. A battery pack, characterized in that, include: Box; as well as, The battery pack according to any one of claims 1-15, wherein a plurality of the battery packs are installed in the housing.

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