Battery pack and electric device

Abstract

This application provides a battery pack and an electrical device, relating to the field of battery technology. The battery pack includes a battery module and a heat exchange device. The first battery is a battery that at least partially overlaps with the orthographic projection of the first bent section on the plane of the first surface. The second battery is a battery that only overlaps with the orthographic projection of the heat exchange tube on the plane of the first surface. On the plane of the first surface, the overlap area between the orthographic projection of the heat exchange device and the first battery is y1mm. 2 The overlap area between the orthographic projection of the heat exchange device and the second battery is y2mm. 2 Satisfying y1mm 2 Greater than y2mm 2 , and y1mm 2 -y2mm 2 =ymm 2 The ratio of the area of ​​the connection surface between the terminal assembly and the busbar to the orthographic projection area of ​​the first end face onto the plane containing the first surface is x; satisfying: 12.63≤y / x≤82772.73. This improves the heat exchange efficiency of the battery, preventing excessive temperature differences between the batteries.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery pack and an electrical device. Background Technology

[0002] In related technologies, battery packs typically employ liquid cooling plates for heat exchange. A liquid cooling plate usually consists of two layers of heat exchange plates forming a chamber, within which multiple spaced heat exchange channels are distributed. However, due to the large size of the heat exchange plates, they are prone to deformation during actual use, and the degree of deformation can be significant. This reduces the contact area between the battery and the liquid cooling plate, increases the contact thermal resistance, and lowers the battery's heat exchange efficiency. Furthermore, the molding process of liquid cooling plates is complex, requiring high welding precision and material properties, which also leads to a generally low production yield. Summary of the Invention

[0003] The purpose of this application is to provide a battery pack and an electrical device to solve the technical problem of poor heat exchange efficiency in existing battery packs.

[0004] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, this application provides a battery pack, including a battery module and a heat exchange device. The battery module has a first surface and includes multiple batteries, at least a first battery and a second battery. Each battery has a first end face with terminal assemblies. The terminal assemblies of adjacent batteries are electrically connected via a busbar. The heat exchange device is heat-exchangeably connected to the first surface of the battery module and includes multiple spaced heat exchange tubes connected to each other via a first bend. The first battery is a battery that at least partially overlaps with the orthographic projection of the first bend onto the plane of the first surface, and the second battery is a battery that only overlaps with the orthographic projection of the heat exchange tubes onto the plane of the first surface. The overlap area between the orthographic projection of the heat exchange device and the first battery on the plane of the first surface is y1mm. 2 The overlapping area between the orthographic projection of the heat exchange device and the second battery is y2mm. 2 Satisfying y1mm 2 Greater than y2mm 2 , and y1mm 2 -y2mm 2 =ymm 2 The ratio of the area of ​​the connection surface between the pole assembly and the busbar to the orthographic projection area of ​​the first end face on the plane where the first surface is located is x; satisfying: 12.63≤y / x≤82772.73.

[0005] The above technical solution has at least the following beneficial technical effects: In the battery pack provided in this application embodiment, the overlap area between the orthographic projection of the heat exchange device and the first battery is controlled to be greater than the overlap area between the orthographic projection of the heat exchange device and the second battery. That is, the heat exchange area between the heat exchange device and the first battery is greater than the heat exchange area between the heat exchange device and the second battery, so as to improve the heat exchange efficiency of the battery at the first bend section of the heat exchange device and avoid the problem of large temperature difference between the battery at the first bend section and the battery at the heat exchange tube.

[0006] Furthermore, by controlling the overlapping area y1 of the orthographic projection of the heat exchange device with the first battery, the overlapping area y2 of the orthographic projection of the heat exchange device with the second battery, and the ratio x of the connection surface area of ​​the electrode assembly and the busbar to the orthographic projection area of ​​the first end face on the plane where the first surface is located, the relationship between these three factors satisfies: y1mm 2 -y2mm 2 =ymm 2 The ratio y / x is defined as 12.63 ≤ y / x ≤ 82772.73. When y / x is less than 12.63, the temperature difference between batteries will be large. When y / x is greater than 82772.73, the overall heat exchange efficiency of the battery module will be poor, and the overall temperature rise of the battery module will be rapid, which may lead to the risk of thermal runaway of the battery pack. Therefore, x and y need to be considered comprehensively, and y / x should be limited to the range of 12.63~82772.73. While ensuring that the heat exchange efficiency of the battery at the first bending section is improved, the ratio x of the connection surface area of ​​the terminal assembly and the busbar to the orthogonal projection area of ​​the first end face on the plane of the first surface is controlled. That is, the heat generation of the battery at the terminal assembly is controlled, so that the temperature difference between batteries is not too large, the temperature rise of the battery is not too large, and the battery safety is improved.

[0007] Secondly, this application provides an electrical device including the battery pack described in the first aspect. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a three-dimensional structural diagram of the battery pack provided in the embodiments of this application.

[0010] Figure 2 This is a schematic diagram of the explosion and disassembly of the battery module and heat exchange device in the battery pack provided in the embodiments of this application.

[0011] Figure 3This is a schematic diagram of the connection between the battery module and the heat exchange device in the battery pack provided in the embodiments of this application.

[0012] Figure 4 This is a partial structural schematic diagram of the heat exchange device in the battery pack provided in the embodiments of this application.

[0013] Figure 5 This is a cross-sectional schematic diagram of the heat exchange tube in the battery pack provided in the embodiments of this application.

[0014] In the figure: 1-Battery module; 2-Heat exchange device; 10-First surface; 11-Battery; 111-First battery; 112-Second battery; 113-First end face; 114-Terminal assembly; 21-Heat exchange tube; 22-First bending section; 23-Current collector; 24-Heat exchange interface; 25-Second bending section; 211-Straight section; 221-Arc section. Detailed Implementation

[0015] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0016] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0017] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, 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 application.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0019] Because liquid cooling plates can easily reduce the heat exchange efficiency of the battery pack, related technologies often use heat exchange bends to replace them for heat exchange. Compared to liquid cooling plates, heat exchange bends have higher forming efficiency, simpler manufacturing processes, and better flatness, enabling more uniform heat exchange with the batteries. However, the applicant's research found that the flow rate of the heat exchange medium at the bend in the integrally bent heat exchange tube is slower, which affects the heat exchange efficiency of the batteries at the bend. This results in a still large temperature difference between batteries, poor overall temperature uniformity of the battery pack, and a decrease in the overall cycle life of the battery pack.

[0020] Based on the above considerations, this application provides a battery pack and an electrical device. This application improves the heat exchange efficiency of the battery at the first bend of the heat exchange device by controlling the overlap area between the orthographic projection of the heat exchange device and the first battery to be greater than the overlap area between the orthographic projection of the heat exchange device and the second battery, i.e., the heat exchange area between the heat exchange device and the first battery is greater than the heat exchange area between the heat exchange device and the second battery, thus avoiding the problem of a large temperature difference between the battery at the first bend and the battery at the heat exchange tube. Furthermore, by controlling the relationship between the overlap area y1 of the orthographic projection of the heat exchange device and the first battery, the overlap area y2 of the orthographic projection of the heat exchange device and the second battery, and the ratio x of the connection surface area of ​​the terminal assembly and the busbar to the orthographic projection area of ​​the first end face on the plane of the first surface, the following condition is met: y1mm 2 -y2mm 2 =ymm 2 12.63≤y / x≤82772.73, while ensuring the improvement of the heat exchange efficiency of the battery at the first bending section, by controlling the ratio x of the connection surface area of ​​the terminal assembly and the busbar to the orthogonal projection area of ​​the first end face on the plane of the first surface, that is, controlling the heat generation of the battery at the terminal assembly, the temperature difference between the batteries will not be too large, the temperature rise of the battery will not be too large, and the safety of the battery is improved.

[0021] The battery pack of this application is applicable to electrical devices that use batteries as a power source. The electrical devices disclosed in the embodiments of this application can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, power tools, energy storage devices, amusement equipment, elevators, and lifting equipment, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, or electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.; energy storage devices can be energy storage walls, base station energy storage, container energy storage, etc.; amusement equipment can be carousels, drop towers, etc.

[0022] This application describes an electrical device using a vehicle as an example. The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery pack is installed inside the vehicle, and the battery pack can be located at the bottom, front, or rear of the vehicle. The battery pack can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. The vehicle may also include a controller and a motor. The controller controls the battery to supply power to the motor, for example, to meet the vehicle's power needs during starting, navigation, and driving. The battery can not only serve as the vehicle's operating power source but also as its driving power source, replacing or partially replacing gasoline or natural gas to provide driving power to the vehicle.

[0023] The aforementioned battery pack can be a battery management system (BMS) and battery modules. Each battery module includes multiple batteries. These batteries can be electrically connected in series, parallel, or a combination of both, and communicate with the BMS, which controls and monitors the operating status of each battery.

[0024] The technical solution of this application will now be described in detail with reference to the accompanying drawings.

[0025] Please refer to Figure 1 and Figure 2 The battery pack provided in this application includes a battery module 1 and a heat exchange device 2. The battery module 1 is formed by connecting multiple batteries 11 with similar capacity and internal resistance in series or in parallel. The battery pack includes a battery management system (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring, etc.), structural components (casing, brackets, etc.), and protective components, etc. The above components are placed in a box and sealed with a cover plate to form a complete functional unit that can directly output electrical energy.

[0026] The heat exchanger 2 serves as a component for regulating the temperature of the battery 11. The heat exchanger is equipped with a heat exchange channel for circulating a heat exchange medium. This medium can be a gas (air), a liquid (such as water, alcohol, refrigerant, oil, etc.), or a solid (such as thermally conductive adhesive, thermally conductive solder paste, etc.). The heat exchange channel has an inlet and an outlet for the heat exchange medium. The heat exchange medium enters the heat exchange channel through the inlet, exchanges heat with the battery 11, and then exits through the outlet, thus achieving heat exchange with the battery. The heat exchanger 2 can be made of one or more of the following materials: aluminum alloy, magnesium alloy, stainless steel, copper, and aluminum.

[0027] Battery 11 can store chemical energy and controllably convert it into electrical energy. In a recyclable battery, the active materials can be reactivated by charging after discharge for continued use. Battery 11 includes a casing and electrode assemblies disposed within the casing. The casing material includes at least one of copper, iron, aluminum, aluminum alloy, stainless steel, etc. The electrode assemblies are the components in the battery where electrochemical reactions occur; they are the smallest units in the battery capable of carrying out electrochemical reactions such as charging / discharging.

[0028] Electrode assemblies are the basic units in a battery. They can be either coiled or stacked. The main body of an electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive and negative electrode sheets. The positive electrode sheet generally includes a positive current collector and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: a positive active material, a conductive agent, and a binder. The positive active material includes, but is not limited to, at least one of the following: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive active materials for batteries. These positive active materials can be used alone or in combination. Lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, and their modified compounds.

[0029] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode active layer includes a negative electrode active material, a conductive component, and a binder. The negative electrode active material can be a carbon-based material such as graphite, porous carbon, hard carbon, soft carbon, or mesophase carbon microspheres, or a silicon-based material such as elemental silicon, silicon oxides, silicon-carbon composites, or silicon-ammonia composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0030] A separator is disposed between the positive and negative electrode plates to separate them and prevent short circuits caused by contact. The separator can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride. A coating can also be applied to the surface of the separator. The coating can be an inorganic coating and / or an organic coating. The inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite; the organic coating includes at least one of aramid coating and polyvinylidene fluoride (PVDF) coating.

[0031] like Figure 1 As shown, the battery pack also includes a housing 3, which is a closed or semi-closed structure made of materials such as metal and plastic. The housing 3 serves as the physical carrier of the battery pack, and its design and manufacturing must meet the safety, reliability, and functionality requirements of the battery pack under different usage scenarios. The housing 3 provides installation space for the battery pack, BMS, cooling system, electrical connection components, etc., and fixes these components within the housing, ensuring they maintain a relatively stable position during battery pack operation and preventing damage or loosening of connections due to vibration, impact, or other factors. The materials of the housing 3 include at least one of steel, aluminum alloy, iron, glass fiber reinforced composite materials, and carbon fiber reinforced composite materials.

[0032] The housing 3 includes a base plate 31 and a frame 32. The base plate 31 is the main load-bearing component of the battery pack, typically referring to a structural component installed at the bottom of the battery pack, used to support and fix the battery pack, battery management system, cooling system, and other components inside the battery pack. The base plate 31 is generally located at the bottom of the frame 32 and is fixedly connected to the bottom of the frame 32. The fixing connection methods include, but are not limited to, welding, riveting, and screwing. The base plate 31 can be made of various materials, such as high-strength materials like aluminum alloy, steel, and stainless steel.

[0033] The battery module 1 has a first surface 10 and includes a plurality of batteries 11. It is understood that the battery module 1 is composed of a plurality of batteries 11 arranged in a specific order. The plurality of batteries 11 includes at least a first battery 111 and a second battery 112. Each battery 11 has a first end face 113, on which a terminal post assembly 114 is provided. The terminal post assemblies 114 between adjacent batteries 11 are electrically connected via a busbar.

[0034] The heat exchange device 2 is heat-exchange connected to the first surface 10 of the battery module 1. The heat exchange device 2 includes a plurality of spaced heat exchange tubes 21, and two heat exchange tubes 21 are connected by a first bend 22. The first battery 111 is a battery 11 that at least partially overlaps with the orthographic projection of the first bend 22 on the plane of the first surface 10. The second battery 112 is a battery 11 that only overlaps with the orthographic projection of the heat exchange tube 21 on the plane of the first surface 10. The overlap area between the orthographic projection of the heat exchange device 2 and the first battery 111 on the plane of the first surface 10 is y1mm. 2 The overlapping area between the orthographic projection of heat exchanger 2 and the second battery 112 is y2mm. 2 Satisfying y1mm 2 Greater than y2mm 2 , and y1mm 2 -y2mm 2 =ymm 2 The ratio of the area of ​​the connection surface between the pole assembly 114 and the busbar to the area of ​​the orthographic projection of the first end face 113 onto the plane of the first surface 10 is x; satisfying: 12.63≤y / x≤82772.73.

[0035] It is understandable that the heat exchange device 2 and the first surface 10 of the battery module 1 can be connected by thermally conductive adhesive or a heat spreader, or they can be directly connected. The key is that the heat exchange device 2 can exchange heat with the battery module 1. The first bending section 22 connects two heat exchange tubes 21, causing the heat exchange medium within the connected tubes to change direction. The tangent of the first bending section 22 at any position in the projection area of ​​the first surface 10 of the battery module 1 intersects the extension direction (i.e., the length direction) of the heat exchange tube 21 in the same plane. It is understood that the first battery 111 is a battery 11 whose orthographic projection at least partially overlaps with the first bending section 22 of the heat exchange device 2. Therefore, the first battery 111 can exchange heat completely with the first bending section 22, or only partially with it. The second battery 112 is a battery 11 that only overlaps with the orthographic projection of the heat exchange tube 21 of the heat exchange device 2. Therefore, there is no orthographic projection of the first bend section 22 on the second battery 112, and it only exchanges heat with the heat exchange tube 21.

[0036] In the technical solution of this application embodiment, by controlling the overlap area between the orthographic projection of the heat exchange device 2 and the first battery 111 to be greater than the overlap area between the orthographic projection of the heat exchange device 2 and the second battery 112, that is, the heat exchange area between the heat exchange device 2 and the first battery 111 is greater than the heat exchange area between the heat exchange device 2 and the second battery 112, the heat exchange efficiency of the battery at the first bend section 22 of the heat exchange device 2 is improved, and the problem of a large temperature difference between the battery 11 at the first bend section 22 and the battery 11 at the heat exchange tube 21 is avoided.

[0037] Furthermore, by controlling the area y1 of the overlapping portion of the orthographic projection of the heat exchange device 2 with the first battery 111, the area y2 of the overlapping portion of the orthographic projection of the heat exchange device 2 with the second battery 112, and the ratio x of the area of ​​the connection surface of the electrode assembly 114 and the busbar to the orthographic projection area of ​​the first end face 113 on the plane where the first surface 10 is located, the relationship between these three factors satisfies: y1mm 2 -y2mm 2 =ymm 2 12.63≤y / x≤82772.73, for example, y / x can be 12.63, 13.77, 23.31, 38.00, 41.55, 73.45, 77.78, 205.20, 3620.80, 12085.48, 36945.10, 48146.51, 49177.05, 54025.45, 57047.62, 66533.96, 70651.43, 76883.33, 82772.73, etc., or any value between any two adjacent values ​​mentioned above. When y / x is less than 12.63, the temperature difference between batteries 11 will be large. When y / x is greater than 82772.73, the overall heat exchange efficiency of the battery module will be poor, and the overall temperature rise of the battery module will be rapid, which may lead to the risk of thermal runaway of the battery pack. Therefore, x and y need to be considered comprehensively, and y / x should be limited to the range of 12.63~82772.73. While ensuring the improvement of the heat exchange efficiency of the first battery 111 at the first bending section 22, the ratio x of the connection surface area of ​​the terminal assembly 114 and the busbar to the orthogonal projection area of ​​the first end face 113 on the plane of the first surface 10 is controlled. That is, the heat generation of battery 11 at the terminal assembly 114 is controlled, so that the temperature difference between batteries is not too large, the temperature rise of the battery is not too large, and the battery safety is improved.

[0038] In some embodiments, y / x satisfies: 73.45 ≤ y / x ≤ 49177.05. For example, y / x can be 73.45, 77.78, 205.20, 3620.80, 12085.48, 36945.10, 48146.51, 49177.05, etc., or any value between any two adjacent values ​​mentioned above. This improves the heat exchange effect of battery 11 while ensuring that the temperature difference between batteries 11 is not too large, thus improving battery safety.

[0039] In some embodiments, the overlap area y1 between the orthographic projection of the heat exchange device 2 and the first battery 111 satisfies: 20mm. 2 ≤y1mm 2 ≤6000mm 2 For example, y1 can be 20mm 2 50mm 2 120mm 2 170mm 2 200mm 2 500mm 2 1000mm 2 1400mm 2 2000mm 2 2600mm 2 3100mm 2 4000mm 2 5000mm 2 6000mm 2 The value can be any value between any two adjacent values ​​mentioned above. This ensures that the heat exchange device 2 and the first battery 111 have sufficient heat exchange area, thereby improving the heat exchange efficiency of the first battery 111 at the first bend section 22.

[0040] In some embodiments, the overlapping area y2 of the orthographic projection of the heat exchange device 2 and the second battery 112 satisfies: 10mm 2 ≤y2mm 2 ≤5400mm 2 For example, y2 can be 10mm 2 20mm 2 50mm 2 120mm 2 170mm 2 200mm 2 500mm 2 1000mm 2 1400mm 2 2000mm 2 2600mm 2 3100mm 24000mm 2 5000mm 2 5400mm 2 The value can be any value between any two adjacent values ​​mentioned above. This ensures that the heat exchange device 2 and the second battery 112 have sufficient heat exchange area, thereby improving the heat exchange efficiency of the second battery 112.

[0041] In some embodiments, y satisfies: 10mm 2 ≤ymm 2 ≤5990mm 2 For example, y can be 10.1 mm. 2 15.2mm 2 18.9mm 2 19.8mm 2 20.2mm 2 20.4mm 2 102.6mm 2 461.3mm 2 899.5mm 2 905.2mm 2 1498.6mm 2 1884.2mm 2 2070.3mm 2 2472.8mm 2 2971.4mm 2 2999.8mm 2 3526.3mm 2 Or 5990mm 2 "etc." can also be any value between any two adjacent values ​​mentioned above. When y is less than 10mm 2 At this time, the heat exchange efficiency of the first battery 111 at the first bend 22 is less than that of the second battery 112 at the heat exchange tube 21, resulting in a large temperature difference between the first battery 111 and the second battery 112; when y is greater than 5990mm 2 At this time, the proportion of the first bend section 22 is too large, and the flow rate of the heat exchange medium is too slow, resulting in a decrease in the overall heat exchange efficiency of the heat exchange device. Therefore, by setting y within the above range, the temperature difference between the batteries 11 is reduced, and the heat exchange efficiency is improved.

[0042] In some embodiments, the connection surface area between the pole assembly 114 and the busbar is 50 mm². 2 ~1600mm 2 For example, it could be 50mm 2 120mm 2 170mm 2 200mm 2 500mm2 1000mm 2 1400mm 2 1600mm 2 The value can be any value between any two adjacent values ​​mentioned above. In this way, while improving the current carrying capacity between the terminal assembly 114 and the busbar, the resistance at the connection between the terminal assembly 114 and the busbar can be controlled within a reasonable range to avoid excessive heat generation.

[0043] In some embodiments, the orthographic projection area of ​​the first end face 113 onto the plane containing the first surface 10 is 1000 mm². 2 ~36000mm 2 For example, it could be 1000mm 2 1200mm 2 2000mm 2 4200mm 2 5000mm 2 8000mm 2 12000mm 2 26000mm 2 30000mm 2 36000mm 2 The value can be any value between any two adjacent values ​​mentioned above. In this way, the first end face 113 of the battery 11 provides sufficient mounting area for functional components on the battery, such as the terminal assembly 114, while ensuring that the first end face 113 of the battery 11 does not occupy too much internal space of the battery pack, thus improving space utilization.

[0044] In some embodiments, x satisfies: 0.01 ≤ x ≤ 0.8. For example, x can be 0.011, 0.035, 0.043, 0.051, 0.053, 0.055, 0.061, 0.105, 0.124, 0.243, 0.250, 0.275, 0.491, 0.500, 0.521, 0.632, 0.652, or 0.800, or any value between any two adjacent values ​​mentioned above. When x is less than 0.01, the resistance of the connection surface between the terminal assembly 114 and the busbar increases, resulting in greater heat generation, faster overall battery temperature rise, and poor overall battery heat exchange efficiency. When x is greater than 0.8, the connection surface area between the terminal assembly 114 and the busbar is too large. This can easily lead to uneven assembly when the terminal assembly 114 of each battery 11 is welded and assembled with the busbar. Consequently, the heat generation at the terminal assembly 114 varies for each battery 11, resulting in a large temperature difference between the batteries 11. Therefore, by setting x within the above range, the temperature difference between the batteries 11 can be reduced, and the heat exchange efficiency can be improved.

[0045] In some embodiments, the first surface 10 and the first end face 113 are disposed opposite to each other, and the electrode assembly 114 and the heat exchange device 2 are respectively disposed on two opposite surfaces of the battery module 1. For example Figure 2 In the example shown, the first end face 113 is located at the top of the battery module 1, and the first surface 10 is located at the bottom of the battery module 1, so that the terminal assembly 114 and the heat exchange device 2 are located on different surfaces. At this time, the battery module 1 is generally placed on the base plate 31, and the heat exchange device 2 is placed between the base plate 31 and the battery module 1, and is heat-exchange connected with the first surface 10 of the battery module 1; the heat exchange device 2 can be bonded and fixed to the base plate 31, or it can be placed directly on the base plate 31.

[0046] By using the above settings, the number of heat exchange tubes 21 in the heat exchange device 2 can be increased, the heat exchange area between the heat exchange device 2 and the battery module 1 can be increased, thereby improving the overall heat exchange efficiency of the battery module 1.

[0047] In other embodiments, the first surface 10 is disposed close to the first end face 113, that is, the first end face 113 is part of the first surface 10, and the electrode assembly 114 and the heat exchange tube 21 are disposed on the same surface of the battery module 1. For example, the first end face 113 is located on the top of the battery module 1, and the first surface 10 is also located on the top of the battery module 1, so that the electrode assembly 114 and the heat exchange device 2 are located on the same surface of the battery module 1.

[0048] By setting it up as described above, the distance between the heat exchange device 2 and the electrode assembly 114 can be reduced, that is, the distance between the heat exchange device 2 and the heat source can be reduced, which can improve the overall heat exchange efficiency of the battery module 1.

[0049] Of course, in some other embodiments, the first end face 113 may also be perpendicular to the first surface 10. For example, when the first surface 10 is located at the bottom of the battery module 1, the first end face 113 may also be the side of the battery 11.

[0050] In some embodiments, please refer to Figure 2 The battery module 1 includes a first direction X and a second direction Y, wherein the first direction X is the length direction of the battery module 1, the second direction Y is the width direction of the battery module 1, and the length direction of the heat exchange tube 21 is parallel to the first direction X.

[0051] The above configuration allows the length of the heat exchange tube 21 to be aligned with the length of the battery module 1. This reduces the number of first bends 22, increases the flow rate of the heat exchange medium within the heat exchange device 2, and thus improves the heat exchange efficiency.

[0052] Of course, in some other embodiments, the length direction of the heat exchange tube 21 may also be parallel to the second direction Y, that is, the length direction of the heat exchange tube 21 is along the width direction of the battery module 1.

[0053] In some embodiments, the battery 11 has a length direction, which is perpendicular to the length direction of the heat exchange tube 21.

[0054] With the above configuration, the same battery 11 can come into contact with more heat exchange tubes 21, and the same heat exchange tube 21 can also come into contact with more batteries 11, thereby improving heat exchange efficiency.

[0055] In some embodiments, please refer to Figure 3 At least two heat exchange tubes 21 are connected to the same battery 11 for heat exchange. It is understood that the same battery 11 can be connected to two, three, four or even more heat exchange tubes 21 for heat exchange.

[0056] By setting the above, the heat exchange area of ​​each battery 11 can be increased, the heat exchange efficiency of the battery 11 can be improved, the temperature rise of each battery 11 can be better controlled, the temperature uniformity of each battery 11 can be improved, and thus the temperature uniformity of the entire battery module can be improved.

[0057] In some embodiments, please refer to Figure 4 Along the arrangement direction of the multiple heat exchange tubes 21, the spacing between two adjacent heat exchange tubes 21 is L1mm, satisfying: 15mm≤L1mm≤200mm. For example, L1mm can be 15mm, 26mm, 45mm, 55mm, 80mm, 100mm, 120mm, 150mm, 180mm, 200mm, etc., or any value between any two adjacent values ​​mentioned above.

[0058] The above configuration ensures that the heat exchange medium within the heat exchange tube 21 can fully exchange heat with the battery 11, preventing heat exchange between adjacent heat exchange tubes 21 and thus avoiding any impact on the heat exchange effect on the battery. When L1mm is less than 15mm, the distance between adjacent heat exchange tubes 21 becomes too small, causing heat exchange interference and reducing the heat exchange efficiency of the battery. When L1mm is greater than 200mm, the distance between adjacent heat exchange tubes 21 becomes too large, resulting in too few heat exchange tubes and reducing the heat exchange efficiency of the battery.

[0059] In some embodiments, please refer to Figure 5 On a plane perpendicular to the length of the heat exchange tube 21, the cross-section of the heat exchange tube 21 includes two oppositely arranged straight sections 211, one of which is heat-exchange connected to the first surface 10. This arrangement increases the heat exchange area between the heat exchange tube 21 and the battery module 1, thereby improving the heat exchange efficiency of the battery module 1.

[0060] In some embodiments, please refer to Figure 5Along the width direction of the heat exchange tube 21, the dimension of the straight section 211 is L0mm, satisfying: 2mm ≤ L0mm ≤ 48mm. For example, L0mm can be 2mm, 5mm, 12mm, 23mm, 28mm, 32mm, 35mm, 45mm, 48mm, etc., or any value between any two adjacent values ​​mentioned above. This ensures that the dimension of the straight section 211 is within the above range, guaranteeing sufficient heat exchange surface between the heat exchange tube 21 and the battery module 1, while also preventing excessive flow resistance of the heat exchange medium inside the heat exchange tube 21, which would affect heat exchange efficiency. When L0mm is less than 2mm, the size of the straight section 211 is too small, the heat exchange surface between the heat exchange tube 21 and the battery module 1 is too small, and the heat exchange efficiency of the battery module 1 is poor. When L0mm is greater than 48mm, the size of the straight section 211 is too large, which will make the heat exchange tube 21 relatively flat, and the flow resistance of the heat exchange medium inside the heat exchange tube 21 will be large, resulting in a slower flow rate of the heat exchange medium, which will reduce the heat exchange efficiency of the battery.

[0061] Please refer to Figure 3 or Figure 4 The first bending segment 22 includes an arc segment 221, the inner radius of which is Rmm, where 7mm ≤ Rmm ≤ 200mm. For example, the inner radius R of the arc segment 221 can be 7mm, 19mm, 25mm, 36mm, 44mm, 56mm, 68mm, 85mm, 120mm, 150mm, 170mm, 200mm, etc., or any value between any two adjacent values ​​mentioned above. This design ensures that the first bending segment 22 is easy to form while preventing excessive temperature differences between the batteries 11. When the inner radius Rmm is less than 7mm, the first bending segment 22 is difficult to process and form, and is prone to breakage; when the inner radius Rmm is greater than 200mm, the proportion of the first bending segment 22 is too large, resulting in a large temperature difference between the batteries 11.

[0062] In some embodiments, please refer to Figure 4 Along the width direction of the heat exchange tube 21, the distance between the centerlines of two adjacent first bend sections 22 is L2mm, satisfying: 37mm ≤ L2mm ≤ 700mm. It can be understood that the centerline of the first bend section 22 refers to the straight line that bisects the first bend section 22, that is, the axis of symmetry of the first bend section 22. For example, L2 can be 37mm, 50mm, 70mm, 120mm, 150mm, 210mm, 350mm, 480mm, 510mm, 680mm, 700mm, etc., or any value between any two adjacent values ​​mentioned above.

[0063] By setting the distance L2 between the centerlines of two adjacent first bends 22 within the aforementioned range, heat exchange efficiency is improved. When L2mm is less than 37mm, the distance between two adjacent heat exchange tubes 21 becomes too small, resulting in heat exchange between them and reducing the heat exchange efficiency of the battery module. When L2mm is greater than 700mm, the distance between two adjacent heat exchange tubes 21 becomes too large, leading to excessive flow resistance of the heat exchange medium within the heat exchange tubes 21 and reducing the heat exchange efficiency of the battery module.

[0064] In some embodiments, to improve the heat exchange efficiency of the first battery 111, the first battery 111 overlaps with the orthographic projections of at least two first bending segments 22 on the plane containing the first surface 10. This is to improve the heat exchange efficiency of the first battery 111 and prevent the temperature difference between it and the second battery 112 from becoming too large. In this embodiment, to avoid an excessive number of first bending segments 22, y satisfies: 10mm. 2 ≤ymm 2 ≤5500mm 2 For example, ymm 2 It can be 10.1mm 2 15.2mm 2 18.9mm 2 19.8mm 2 20.2mm 2 20.4mm 2 102.6mm 2 461.3mm 2 899.5mm 2 905.2mm 2 1498.6mm 2 1884.2mm 2 2070.3mm 2 2472.8mm 2 2971.4mm 2 2999.8mm 2 3526.3mm 2 Or 5500mm 2 "etc." can also be any value between any two adjacent values ​​mentioned above. By making ymm 2 The above-mentioned range is limited to avoid an excessive number of first bends 22, which would cause the flow rate of the heat exchange medium at the first bends 22 to be too slow, resulting in a decrease in the overall heat exchange efficiency of the heat exchange device. This ensures, in this embodiment, that the overall heat exchange efficiency of the battery is improved, and the battery temperature is kept uniform.

[0065] In some embodiments, the wall thickness of the first bend 22 is less than the wall thickness of the heat exchange tube 21. Thus, the cross-sectional area of ​​the heat exchange channel within the first bend 22 is greater than that within the heat exchange tube 21, resulting in a higher flow rate of the heat exchange medium at the first bend 22 than at the heat exchange tube 21. This improves the heat exchange efficiency at the first bend 22 and avoids the problem of a large temperature difference between the battery 11 at the first bend 22 and the battery 11 at the heat exchange tube 21.

[0066] In some embodiments, when the positive electrode active material of the positive electrode sheet of battery 11 is a layered transition metal oxide, the layered transition metal oxide includes nickel-cobalt-manganese ternary materials and / or nickel-cobalt-aluminum ternary materials, wherein the nickel-cobalt-manganese ternary materials satisfy the general chemical formula LiNi. x1 Co y3 Mn z M f O2, where 0.1 < x1 < 1, 0.1 < y3 < 1, 0.1 < z < 1, and x1 + y3 + z + f = 1, M is a doping element, and M includes at least one of Al, Mg, Ti, Zr, B, P, Nb, Ta, W, Zr, and V. In this embodiment, the battery 11 generates a large amount of heat. To avoid the overall temperature rise of the battery being too rapid, the ratio x of the connection surface area of ​​the terminal assembly 114 and the busbar to the orthogonal projection area of ​​the first end face 113 on the plane where the first surface 10 is located satisfies: 0.02 ≤ x ≤ 0.8. For example, x can be 0.02, 0.035, 0.043, 0.051, 0.053, 0.055, 0.061, 0.105, 0.124, 0.243, 0.250, 0.275, 0.491, 0.500, 0.521, 0.632, 0.652, or 0.800, or any value between any two adjacent values ​​mentioned above. This setting appropriately increases the value of x to improve the overall heat exchange efficiency of the battery, preventing excessive heat generation inside battery 11, which could lead to a rapid temperature rise and negatively impact heat exchange efficiency.

[0067] In some embodiments, the first bent segment 22 is located at the end of the battery module 1, that is, on the plane where the first surface 10 is located, the orthographic projection of the first bent segment 22 overlaps with the orthographic projection of the battery 11 located at the end (outermost) of the battery module 1. Wherein, 20 ≤ y / x ≤ 82772.73. For example, y / x can be 20, 23.31, 38.00, 41.55, 73.45, 77.78, 205.20, 3620.80, 12085.48, 36945.10, 48146.51, 49177.05, 54025.45, 57047.62, 66533.96, 70651.43, 76883.33, 81772.73, etc., or any value between any two adjacent values ​​mentioned above. It is understood that the first bending segment 22 can be located at the end of the battery module 1 along its length direction or at the end of the battery module 1 along its width direction. The battery 11 located at the end of the battery module 1 can also exchange heat through contact with the battery pack housing. Therefore, y / x can be limited to the above range. Appropriately increasing the y / x value can improve the heat exchange efficiency of the heat exchange device 2.

[0068] In some embodiments, the thickness of the battery 11 is ≥30mm, wherein y1 ≥ 150mm. 2 For example, y1 can be 150mm. 2 170mm 2 200mm 2 500mm 2 1000mm 2 1400mm 2 2000mm 2 2600mm 2 3100mm 2 4000mm 2 5000mm 2 6000mm 2 The value can be any value between any two adjacent values ​​mentioned above. In this embodiment, since the battery 11 is relatively thick, its capacity and heat generation are relatively large. Therefore, the area y1 of the overlapping portion of the orthographic projection of the first bending segment 22 and the first battery 111 can be designed to be relatively large, thereby improving the heat exchange efficiency of the first battery 111.

[0069] In some embodiments, when the thickness of battery 11 is ≥30mm, 12.63≤y / x≤80000. For example, y / x can be 12.63, 13.77, 23.31, 38.00, 41.55, 73.45, 77.78, 205.20, 3620.80, 12085.48, 36945.10, 48146.51, 49177.05, 54025.45, 57047.62, 66533.96, 70651.43, 76883.33, 80000, etc., or any value between any two adjacent values ​​mentioned above. In this embodiment, since battery 11 is relatively thick, its capacity and heat generation are relatively large. Therefore, in order to improve the heat exchange efficiency of battery 11, y / x is set within the above range, and the value of y / x is not too large.

[0070] In some embodiments, the heat exchange tube 21 and the first bent section 22 are integrally formed, and multiple heat exchange tubes 21 are integrally formed, which can improve the forming efficiency, reduce the flow resistance of the heat exchange medium, and improve the heat exchange effect.

[0071] In some embodiments, please refer to Figure 2 , Figure 3 and Figure 4 The heat exchange device 2 further includes a manifold 23 and a heat exchange interface 24. The heat exchange interface 24 can be a connector pipe of the heat exchange device 2. The manifold 23 can be used to connect to the heat exchange interface 24 of the heat exchange device 2 to collect and distribute the heat exchange medium as quickly as possible, allowing the heat exchange medium to flow into the heat exchange channel of the heat exchange tube. The heat exchange tube 21 is connected to the manifold 23 through the heat exchange interface 24. In some embodiments, please refer to Figure 4 The heat exchange interface 24 and the heat exchange tube 21 are connected by a second bend 25, which connects the heat exchange tube 21 and the heat exchange interface 24, causing the heat exchange medium to change direction. On a plane perpendicular to the flow direction of the heat exchange medium, the cross-sectional area of ​​the chamber inside the manifold 23 is larger than the cross-sectional area of ​​the heat exchange channel of a single heat exchange tube 21. This increases the inflow and outflow rate of the heat exchange medium, thereby improving heat exchange efficiency.

[0072] In some embodiments, the heat exchange interface 24 is located at one end of the battery module 1. Specifically, the heat exchange interface 24 is located at one end along the length of the battery module 1. It is understood that the heat exchange interface 24 may be spaced apart from the battery module 1, or it may be located at the top or bottom edge of the battery module 1, in order to avoid short circuits caused by contact between the heat exchange interface 24 and the electrical connectors on the battery module 1, thereby improving insulation performance.

[0073] In some embodiments, the heat exchange tube 21 is made of aluminum alloy, which includes at least Al, Cu and Mn, wherein the mass percentage of Al is greater than or equal to 95wt%, and the sum of the mass percentages of Cu and Mn is 1wt% to 1.7wt%.

[0074] The above-mentioned settings are designed to improve the corrosion resistance of the heat exchange tube 21, making it less susceptible to corrosion by the heat exchange medium or surrounding gas, thereby increasing the strength of the heat exchange tube 21 and ultimately improving the overall safety of the battery. The testing method for the elemental content in the aluminum alloy is in accordance with GB / T 7999-2015, "Direct Reading Photoelectric Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys".

[0075] In some other embodiments, the heat exchange tube 21 may also be made of stainless steel, which includes Cr, wherein the mass percentage of Cr is 14wt%~23wt%.

[0076] The above settings improve the corrosion resistance of the heat exchange tube 21, making it less susceptible to corrosion by the heat exchange medium or surrounding gas, thus increasing the strength of the heat exchange tube 21 and ultimately enhancing the overall safety of the battery. The test method for the elemental content in stainless steel refers to GB / T 11170-2008, "Determination of Multi-Element Content in Stainless Steel by Spark Discharge Atomic Emission Spectrometry (Conventional Method)".

[0077] The battery pack provided in this application will be described in detail below through specific embodiments.

[0078] It should be noted that the dimensions of the parameters such as length, width, height, distance, thickness, and wall thickness in this application can be measured by micrometer, vernier caliper, or laser rangefinder. The appropriate instrument can be selected according to the accuracy and range of the measurement.

[0079] Among them, the ymm of this application 2 Methods for testing values: The battery pack was disassembled, the bottom plate and the top cover were removed, and the interior of the battery pack, including the heat exchange tubes, was scanned using a blue light scanner to generate accurate point cloud data. This data was then reconstructed into a 3D model, and the y1 mm value was calculated using software. 2 and y2 mm 2 According to the formula y=y1-y2, ymm is calculated. 2 .

[0080] The method for testing the x-value in this application is as follows: Use a vernier caliper (accuracy 0.05mm) to measure the diameter or side length of the connection surface between the terminal assembly and the busbar. If the connection surface is circular, measure the diameter of the connection surface and record it as r (unit: mm). Then, use the formula s1 = π × r. 2The area of ​​the connection surface between the terminal assembly and the busbar is calculated. If the connection surface between the terminal assembly and the busbar is square, the length of the long side of the connection surface is measured and recorded as L1 (unit: mm) and the length of the short side is recorded as L2 (unit: mm). According to the formula s1=L1×L2, the area of ​​the connection surface between the terminal assembly and the busbar is calculated. The length of the long side of the first end face is measured using a (unit: mm) and the length of the short side is recorded as b (unit: mm) using a vernier caliper (accuracy 0.05 mm). According to the formula S2=a×b, the area of ​​the first end face where the terminal assembly is located is calculated. According to the formula x=(S1 / S2)×100%, the value of x is calculated.

[0081] Method for preparing battery 11.

[0082] (1) Preparation of the positive electrode: The prepared positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF) are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the positive electrode sheet is obtained by rolling and slitting.

[0083] Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98): (4~1): (4~1).

[0084] (2) Preparation of negative electrode: The negative electrode active material, conductive agent (e.g., acetylene black), thickener (e.g., carboxymethyl cellulose (CMC)), and binder (e.g., styrene-butadiene rubber (SBR)) are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the negative electrode sheet is obtained by rolling and slitting.

[0085] Specifically, the mass ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0086] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0087] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0088] (5) Preparation of lithium-ion batteries: The positive electrode, separator, and negative electrode are stacked in sequence and formed into a bare cell by winding or stacking. The bare cell is then placed in a battery casing, which is a prismatic casing. The battery is dried, injected with electrolyte, and then packaged, allowed to stand, formed, and calibrated to obtain a lithium-ion battery.

[0089] In the selection of materials for the aforementioned battery, this application may also select other materials, not limited to those limited by the above preparation method. The positive electrode active material may be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate. The conductive agent in the positive electrode sheet may also be selected from one or more of graphite, superconducting carbon, Ketjen black, Super P, carbon nanotubes, graphene, and carbon nanofibers. The binder in the positive electrode sheet may also be selected from one or more of polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan. The positive electrode current collector may also be selected from one or more of stainless steel with surface silver plating, stainless steel, aluminum, nickel, carbon electrode, carbon, nickel, and titanium.

[0090] The negative electrode active material can be selected from one or more of the following negative electrode active main materials: artificial graphite, natural graphite, silicon carbide, silicon oxide, lithium titanate, etc.; the conductive agent in the negative electrode sheet can be selected from one or more of the following: conductive carbon black, conductive graphite, carbon nanotubes, graphene, carbon fiber, etc.; the binder in the negative electrode sheet can be selected from one or more of the following: styrene-butadiene rubber, polyacrylic acid and its salts, sodium alginate, etc.; the thickener in the negative electrode sheet can be selected from one or more of the following: sodium carboxymethyl cellulose, polyacrylonitrile multi-component copolymer, etc.; the negative electrode current collector can also be selected from one or more of the following: stainless steel with silver plating, stainless steel, copper, nickel, carbon electrode, carbon, nickel, titanium, etc.

[0091] Test Method 1: Heat exchanger heat dissipation effect test.

[0092] Battery 11 is prepared according to the above method. Multiple batteries 11 are stacked to form battery module 1. Adjacent batteries 11 in battery module 1 are electrically connected through conductive busbars. The heat exchange interface 24 in heat exchange device 2 is connected to the current collector and fixed by welding. Heat exchange medium (ethylene glycol aqueous solution is selected as the heat exchange medium) is introduced into heat exchange tube 21. At the same time, heat exchange device 2 is heat exchanged with the first surface 10 of battery module 1. NTC (Negative Temperature Coefficient) thermistors are pasted at the same position away from the surface of heat exchange device 2 in each battery shell. The temperature measured on the NTC thermistor is collected in real time through data acquisition line. After installation, the cover is closed and fixed to assemble into battery pack. The x and y values ​​of the heat exchange device in each embodiment and comparative example are shown in Table 1 below. All other structures are the same.

[0093] With the ambient temperature set at 25℃±2℃, the batteries in the battery pack are charged at a rate of 1C to their upper limit voltage. The battery temperature measured by each NTC thermistor is recorded, and the highest measured temperature is used as an indicator of the heat dissipation effect of the heat exchange device 2 in the battery pack. A maximum temperature of 55℃ or less for battery 11 is considered good; a maximum temperature of 60℃ or less but greater than 55℃ for battery 11 is considered acceptable; a maximum temperature of 60℃ or more for battery 11 is considered unacceptable.

[0094] Different battery systems require corresponding adjustments to their upper and lower voltage limits: For cathode active materials including LFP (LiFePO4, lithium iron phosphate) – upper limit voltage 3.65V, lower limit voltage 2.5V; for cathode active materials including NCM (lithium nickel cobalt manganese oxide) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including LFMP (lithium manganese iron phosphate) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including lithium nickel manganese oxide – upper limit voltage 4.8V, lower limit voltage 3.5V.

[0095] The positive electrode active material used in this test was selected from LiNi. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, all other positive electrode active materials meet the above test requirements, and the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and all other negative electrode active materials meet the above test requirements, and the mass ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2; the bare cell is a wound cell, and other cell forms meet the above test requirements.

[0096] Test method 2: Temperature difference test.

[0097] Battery 11 is prepared according to the above method. Multiple batteries 11 are stacked to form battery module 1. Adjacent batteries 11 in battery module 1 are electrically connected through conductive busbars. The heat exchange interface 24 in heat exchange device 2 is connected to the current collector and fixed by welding. Heat exchange medium (ethylene glycol aqueous solution is selected as the heat exchange medium) is introduced into heat exchange tube 21. At the same time, heat exchange device 2 is heat exchanged with the first surface 10 of battery module 1. NTC (Negative Temperature Coefficient) thermistors are pasted at the same position away from the surface of heat exchange device in each battery shell. The temperature measured on the NTC thermistor is collected in real time through data acquisition line. After installation, the cover is closed and fixed to assemble into battery pack. The x and y values ​​of the heat exchange device in each embodiment and comparative example are shown in Table 1 below. All other structures are the same.

[0098] With the ambient temperature set at 25℃±2℃, charge the batteries in the battery pack at a 1C rate to their upper limit voltage. Record the battery temperature measured by each NTC thermistor. The highest battery temperature in the battery module is recorded as T1, and the lowest battery temperature is recorded as T2. Calculate the temperature difference between the highest and lowest temperature batteries in the battery module using the formula: Temperature Difference = T1 - T2. If the temperature difference is ≤2℃, it is considered good; if the temperature difference is greater than 2℃ but ≤5℃, it is considered acceptable; and if the temperature difference is greater than 5℃, it is considered unacceptable.

[0099] Different battery systems require corresponding adjustments to their upper and lower voltage limits: For cathode active materials including LFP (LiFePO4, lithium iron phosphate) – upper limit voltage 3.65V, lower limit voltage 2.5V; for cathode active materials including NCM (lithium nickel cobalt manganese oxide) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including LFMP (lithium manganese iron phosphate) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including lithium nickel manganese oxide – upper limit voltage 4.8V, lower limit voltage 3.5V.

[0100] The positive electrode active material used in this test was selected from LiNi. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, all other positive electrode active materials meet the above test requirements, and the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and all other negative electrode active materials meet the above test requirements, and the mass ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2; the bare cell is a wound cell, and other cell forms meet the above test requirements.

[0101] Table 1 As shown in Table 1 above, compared with Comparative Examples 1 to 4, in Examples 1 to 19, y / x satisfies: 12.63≤y / x≤82772.73. Therefore, the heat dissipation effect test is qualified or good. That is, in Examples 1 to 19, the highest temperature of battery 11 is less than or equal to 60°C, and the temperature difference test is qualified or good. The temperature difference of battery 11 in battery module 1 is less than or equal to 5°C, and the temperature difference test is qualified or good.

[0102] In Comparative Example 1, the y value is less than 10, which is too small. This results in y / x being less than 12.63. The small y / x will cause the temperature difference of battery 11 in battery module 1 to be greater than 5℃. The temperature difference between batteries 11 is large, so the temperature difference test is unqualified.

[0103] In Comparative Example 2, the x value is less than 0.01, which is too small. This results in y / x being greater than 82772.73, which is too large. As a result, the highest temperature of battery 11 in battery module 1 is greater than 60℃, and the overall heat exchange efficiency of battery module 1 is poor. Therefore, the heat dissipation performance test is unqualified.

[0104] In Comparative Example 3, the y value is less than 10, which is too small, and the x value is greater than 0.8, which is too large. This results in y / x being less than 12.63, which is too small. Consequently, the temperature difference between batteries 11 in battery module 1 is greater than 5℃, and the temperature difference between batteries 11 is relatively large. Therefore, the temperature difference test is unqualified.

[0105] In Comparative Example 4, the y value is greater than 5990, which is too large. This results in y / x being greater than 82772.73, which is also too large. As a result, the highest temperature of battery 11 in battery module 1 is greater than 60℃, and the overall heat exchange efficiency of battery module 1 is poor. Therefore, the heat dissipation performance test is unqualified.

[0106] Compared to Examples 12 to 19, although y / x is in the range of 12.63 to 82772.73 in Examples 1 to 3, the y / x value is less than 73.45, which is relatively small. This results in a temperature difference between batteries 11 that is greater than 2°C and ≤5°C. The temperature difference between batteries 11 is relatively large, so the temperature difference test is qualified. In Examples 12 to 19, y / x is in the range of 73.45 to 49177.05, and the temperature difference between batteries 11 is ≤2°C, so the temperature difference test is good.

[0107] Compared to Examples 12 to 19, although y / x is within the range of 12.63 to 82772.73 in Examples 4 to 7, the y / x value is greater than 49177.05, which is relatively large. The highest temperature of battery 11 in battery module 1 is less than or equal to 60°C but greater than 55°C, and the heat dissipation effect test is qualified. In Examples 12 to 19, the y / x value is within the range of 73.45 to 49177.05, the highest temperature of battery 11 in battery module 1 is less than or equal to 55°C, and the heat dissipation effect test is good.

[0108] In Example 8, compared to Examples 12 to 19, the y value is less than 10. This results in y / x being less than 73.45, which is relatively small, even though y / x is in the range of 12.63 to 82772.73. Consequently, the temperature difference between batteries 11 is greater than 2°C and ≤5°C. The temperature difference between batteries 11 is relatively large, therefore, the temperature difference test is qualified. In contrast, in Examples 12 to 19, the temperature difference between batteries 11 is ≤2°C, and the temperature difference test is good.

[0109] In Example 9, the x value is smaller than that in Examples 12 to 19. As a result, although y / x is in the range of 12.63 to 82772.73, the y / x value is greater than 49177.05, which is relatively large. The highest temperature of battery 11 in battery module 1 is less than or equal to 60°C but greater than 55°C, and the heat dissipation effect test is qualified. In contrast, in Examples 12 to 19, the highest temperature of battery 11 in battery module 1 is less than or equal to 55°C, and the heat dissipation effect test is good.

[0110] In Example 10, although y / x is within the range of 12.63 to 82772.73, the y / x value is less than 73.45, which is relatively small. This results in a temperature difference between batteries 11 that is greater than 2°C and ≤5°C. The temperature difference between batteries 11 is relatively large, so the temperature difference test is qualified. In contrast, in Examples 12 to 19, the temperature difference between batteries 11 is ≤2°C, and the temperature difference test is good.

[0111] Compared to Examples 12 to 19, although y / x is in the range of 12.63 to 82772.73, the y / x value is greater than 49177.05, which is relatively large. The highest temperature of battery 11 in battery module 1 is less than or equal to 60°C but greater than 55°C, and the heat dissipation effect test is qualified. In contrast, in Examples 12 to 19, the highest temperature of battery 11 in battery module 1 is less than or equal to 55°C, and the heat dissipation effect test is good.

[0112] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery pack, characterized in that, include: A battery module (1) has a first surface (10). The battery module (1) includes a plurality of batteries (11), of which at least a first battery (111) and a second battery (112) are included. Each battery (11) has a first end face (113) on which a terminal assembly (114) is provided. The terminal assemblies (114) between two adjacent batteries (11) are electrically connected through a busbar. A heat exchange device (2) is heat-exchange connected to the first surface (10) of the battery module (1). The heat exchange device (2) includes a plurality of spaced heat exchange tubes (21). Two heat exchange tubes (21) are connected by a first bend (22). The first battery (111) is a battery (11) that overlaps at least partially with the orthographic projection of the first bend (22) on the plane of the first surface (10). The second battery (112) is a battery (11) that overlaps only with the orthographic projection of the heat exchange tube (21) on the plane of the first surface (10). On the plane of the first surface (10), the overlap area between the orthographic projection of the heat exchange device (2) and the first battery (111) is y1mm. 2 The overlap area between the orthographic projection of the heat exchange device (2) and the second battery (112) is y2mm. 2 Satisfying y1mm 2 Greater than y2mm 2 , and y1mm 2 -y2mm 2 =ymm 2 The ratio of the area of ​​the connection surface between the pole assembly (114) and the busbar to the area of ​​the orthographic projection of the first end face (113) on the plane of the first surface (10) is x; satisfying: 12.63≤y / x≤82772.

73.

2. The battery pack according to claim 1, characterized in that, The first surface (10) and the first end face (113) are arranged opposite to each other, and the pole assembly (114) and the heat exchange device (2) are respectively arranged on two opposite surfaces of the battery module (1).

3. The battery pack according to claim 1, characterized in that, The first surface (10) and the first end face (113) are located on the same plane, and the pole assembly (114) and the heat exchange device (2) are located on the same surface of the battery module (1).

4. The battery pack according to claim 1, characterized in that, The battery module (1) includes a first direction (X) and a second direction (Y), wherein the first direction (X) is the length direction of the battery module (1), the second direction (Y) is the width direction of the battery module (1), and the length direction of the heat exchange tube (21) is parallel to the first direction (X).

5. The battery pack according to claim 1, characterized in that, The battery (11) has a length direction, and the length direction of the battery (11) is perpendicular to the length direction of the heat exchange tube (21).

6. The battery pack according to claim 5, characterized in that, At least two of the heat exchange tubes (21) are heat exchanged with the same battery (11).

7. The battery pack according to claim 1, characterized in that, Along the arrangement direction of the plurality of heat exchange tubes (21), the distance between two adjacent heat exchange tubes (21) is L1mm, satisfying: 15mm≤L1mm≤200mm.

8. The battery pack according to claim 1, characterized in that, On a plane perpendicular to the length direction of the heat exchange tube (21), the cross-section of the heat exchange tube (21) includes two straight sections (211) arranged opposite each other, one of which is heat exchanged with the first surface (10).

9. The battery pack according to claim 8, characterized in that, Along the width direction of the heat exchange tube (21), the dimension of the straight section (211) is L0mm, which satisfies: 2mm≤L0mm≤48mm.

10. The battery pack according to claim 1, characterized in that, The first bending segment (22) includes an arc segment (221), the inner radius of the arc segment (221) is Rmm, which satisfies: 7mm≤Rmm≤200mm.

11. The battery pack according to claim 1, characterized in that, The first battery (111) overlaps with the orthographic projection of at least two of the first bends (22) onto the plane of the first surface (10).

12. The battery pack according to claim 11, characterized in that, ymm 2 Meets the requirement of 10mm 2 ≤ymm 2 ≤5500mm 2 .

13. The battery pack according to any one of claims 1 to 12, characterized in that, The wall thickness of the first bent section (22) is less than the wall thickness of the heat exchange tube (21).

14. The battery pack according to any one of claims 1 to 12, characterized in that, The battery (11) includes an electrode assembly, the electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material, the positive electrode active material is a layered transition metal oxide, wherein x satisfies: 0.02≤x≤0.

8.

15. The battery pack according to any one of claims 1 to 12, characterized in that, The first bending segment (22) is located at the end of the battery module (1) and satisfies: 20≤y / x≤82772.

73.

16. The battery pack according to any one of claims 1 to 12, characterized in that, Meets the requirement of 10mm 2 ≤ymm 2 ≤5990mm 2 ; and / or, 0.01≤x≤0.8。 17. The battery pack according to any one of claims 1 to 12, characterized in that, The thickness of the battery (11) is ≥30mm, wherein y1 ≥150mm. 2 .

18. The battery pack according to any one of claims 1 to 12, characterized in that, The thickness of the battery (11) is ≥30mm, wherein: 12.63≤y / x≤80000.

19. The battery pack according to any one of claims 1 to 12, characterized in that, The heat exchange tube (21) and the first bent section (22) are integrally formed, and the plurality of heat exchange tubes (21) are integrally formed.

20. The battery pack according to claim 19, characterized in that, The heat exchange device (2) further includes: Current collector (23); The heat exchange interface (24) is used to connect the heat exchange tube (21) and the manifold (23). On a plane perpendicular to the flow direction of the heat exchange medium, the cross-sectional area of ​​the chamber inside the manifold (23) is larger than the cross-sectional area of ​​the heat exchange channel inside a single heat exchange tube (21).

21. The battery pack according to claim 20, characterized in that, The heat exchange interface (24) is located at the end of the battery module (1).

22. The battery pack according to any one of claims 1 to 12, characterized in that, The heat exchange tube (21) is made of aluminum alloy, which includes at least Al, Cu and Mn, wherein the mass percentage of Al is greater than or equal to 95wt%, and the sum of the mass percentages of Cu and Mn is 1wt%~1.7wt%.

23. The battery pack according to any one of claims 1 to 12, characterized in that, The heat exchange tube (21) is made of stainless steel, and the stainless steel material includes Cr, wherein the mass percentage of Cr is 14wt%~23wt%.

24. An electrical appliance, characterized in that, Includes the battery pack as described in any one of claims 1 to 23.

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