Battery pack and electric device

Abstract

The application discloses a battery pack and an electric device, and relates to the technical field of batteries, which comprises a box body and a battery group arranged in the box body, the battery group is arranged in layers along a first direction, and a partition plate is arranged between adjacent battery groups; the battery group comprises a plurality of battery monomers, and the plurality of battery monomers corresponding to each battery group are arranged in the same layer along a second direction; the battery monomer comprises a shell and a pole arranged on the shell, and the pole is arranged on a first side of the shell; the box body further comprises a first side plate, and the orthographic projection of the multilayer battery group at least partially coincides with the large face of the first side plate along the direction perpendicular to the large face of the first side plate; the partition plate, a bottom plate, a top plate and the first side plate are internally provided with heat exchange channels, and the battery monomer is in heat exchange connection with the adjacent baffle, partition plate and first side plate. The battery pack and the electric device of the application have better heat exchange uniformity between the battery monomers and the battery groups in the battery pack, higher heat exchange efficiency of the battery, and longer cycle service life of the battery pack.

Description

Technical Field

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

[0002] Battery packs, as energy storage devices, are increasingly widely used in daily life and industry. With market demands for high energy density, capacity, and lifespan, and to meet the requirements of fast charging, higher demands are placed on the thermal management of battery packs. Heavy-duty truck battery packs, in particular, typically employ a multi-layered battery stacking method. The battery packs use upper and lower cooling plates to exchange heat between the bottom and top surfaces of the batteries, increasing the cooling area. However, because the battery terminals are located on top, the area of ​​the upper cooling plate is affected, resulting in poor heat exchange uniformity between the upper and lower cooling plates. This can easily lead to localized lithium plating issues within the battery. Furthermore, uneven heat exchange between different battery cells within the pack reduces the battery's cycle life. Summary of the Invention

[0003] In view of this, on the one hand, the present invention provides a battery pack in which the heat exchange uniformity between individual battery cells and the battery pack is better, the heat exchange efficiency of the battery is higher, and the cycle life of the battery pack is extended.

[0004] On the other hand, the present invention also provides an electrical device.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A battery pack includes a housing and at least two layers of battery packs disposed within the housing. The at least two layers of battery packs are arranged in layers along a first direction. A partition is provided between adjacent battery packs along the first direction, and a baffle is provided on the side of each battery pack away from the partition. The housing includes a frame, a bottom plate, and a top plate. The first direction is perpendicular to the large surface direction of the bottom plate. The battery packs are placed in a receiving cavity enclosed by the frame, bottom plate, and top plate. The baffle includes the bottom plate and the top plate. Each battery pack includes multiple battery cells. The multiple battery cells corresponding to the battery pack are arranged in the same layer along a second direction, which is the length direction of the partition and perpendicular to the large surface of the battery cell. Each battery cell includes a housing and an electrode post disposed on the housing. The electrode post is disposed on a first side surface of the housing, which is perpendicular to the bottom plate. The housing also includes a first side plate, which is perpendicular to the bottom plate and parallel to the first side surface. Along the direction perpendicular to the large surface of the first side plate, the orthographic projection of the multiple layers of battery packs at least partially coincides with the large surface of the first side plate. The partition plate, bottom plate, top plate and first side plate are respectively provided with heat exchange channels for containing heat exchange medium, and the battery cell is heat exchanged with the baffle, partition plate and first side plate arranged nearby.

[0006] As can be seen from the above technical solution, the battery pack provided by the present invention, through multi-layer battery packs arranged along the height direction, with multiple batteries in each layer arranged in a direction perpendicular to the large surface of the battery, improves the overall energy density of the battery pack. Furthermore, heat exchange plates are provided at the top and bottom of at least one layer of battery packs, and heat exchange channels containing heat exchange medium are provided inside the heat exchange plates, increasing the heat exchange area of ​​the battery, improving the heat exchange rate of the battery, and further shortening the charging time of the battery. At the same time, by setting the terminal posts of the battery cells on the first side perpendicular to the bottom plate, the cooling plates at the top and bottom of the battery pack provide uniform cooling to the top and bottom of the battery casing, reducing the temperature difference at different locations of the battery cells, and making the coverage area of ​​the heat exchange structure on the top and bottom surfaces of the battery pack balanced. This also increases the effective heat exchange area of ​​the battery casing, improves the uniformity of heat exchange to the battery cells, and further avoids the top of the terminal posts occupying the top space of the battery cells, reserving sufficient space for the setting of the heat exchange structure on the top surface of the battery cells. Simultaneously, a first side plate parallel to the first side surface is provided, and a flow channel for accommodating the heat exchange medium is also provided within the first side plate, thereby achieving heat exchange on the side of the battery cell perpendicular to the bottom plate. At least three surfaces of the battery casing are heat-exchange connected to the cold plate, improving the heat exchange rate of the battery casing. The first side plate and all batteries in the single-layer battery pack are in heat-exchange contact, further improving the uniform heat exchange of multiple battery components within the battery pack. The above arrangement ensures that all batteries in the same layer of the battery pack are heat-exchange connected to the separator, bottom plate, top plate, and first side plate respectively, guaranteeing uniform cooling of multiple surfaces of the battery. The battery pack of the present invention effectively improves the temperature difference distribution of the battery cells along the first direction, reduces the risk of lithium plating caused by local overcooling or uneven heat dissipation, ensures that multi-layer battery packs stacked along the height direction can obtain a uniform cooling effect, eliminates the heat exchange imbalance between different battery packs, improves the overall temperature uniformity of the battery pack, and extends the cycle life of the battery pack.

[0007] The present invention also provides an electrical device including the battery pack described above.

[0008] The electrical device of the present invention has the battery pack described above, and therefore has the beneficial effects of the battery pack described above, which will not be repeated here. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a structural schematic diagram of a battery pack (with one side frame removed) provided in an embodiment of the present invention at one angle; Figure 2 for Figure 1 A structural diagram of the battery pack from another angle; Figure 3 for Figure 1 A schematic diagram of the battery pack after removing the top plate; Figure 4 A structural schematic diagram of a box body (one side frame plate with the edge removed) provided in an embodiment of the present invention at one angle; Figure 5 for Figure 4 A structural diagram of the box from another angle; Figure 6 for Figure 4 A schematic diagram of the structure of the box after the top plate has been removed; Figure 7 This is a schematic diagram of the structure of a battery cell provided in an embodiment of the present invention; Figure 8 This is a structural schematic diagram of the first side plate at one angle provided in an embodiment of the present invention; Figure 9 This is a structural schematic diagram of the first side plate from another angle, provided in an embodiment of the present invention. Figure 10 This is a schematic diagram of the structure of the bottommost battery cell placed on the base plate according to an embodiment of the present invention; Figure 11 A schematic diagram of the structure of the bottommost battery cell placed on the base plate, according to another embodiment of the present invention; Figure 12 This is a schematic diagram of the structure of the bottommost battery cell placed on the base plate, as provided in the third embodiment of the present invention. Figure 13 A schematic diagram of the structure of a partition plate at one angle provided in an embodiment of the present invention; Figure 14 This is a structural schematic diagram of the partition plate provided in an embodiment of the present invention from another angle; Figure 15 for Figure 14 A cross-sectional view of the AA position in the diagram; Figure 16This is a structural schematic diagram of the base plate at one angle provided in an embodiment of the present invention; Figure 17 This is a structural schematic diagram of the base plate from another angle provided in an embodiment of the present invention; Figure 18 This is a schematic diagram of the structure of the top plate provided in an embodiment of the present invention; Figure 19 This is a schematic diagram showing the positions of the four corner lithium-ion battery cells near the bottom plate and the two lithium-ion battery cells at the center point in the battery pack measured during the test of this invention.

[0011] in: 1. Box body, 101. Frame; 102. Base plate; 1021. Third flow channel; 10211. Third inlet flow channel; 10212. Third return flow channel; 103. Top plate; 1031. Fourth flow channel; 104. First side plate; 1041. First flow channel; 10411. First inlet flow channel; 10412. First return flow channel; 1042. Separator rib; 1043. Inlet; 1044. Outlet; 105. Structural reinforcing plate. 2. Battery pack 201. Battery cell; 2011. Terminal post; 2012. First side surface; 2013. Second side surface. 3. Divider, 301, Second flow channel; 3011, Second inlet flow channel; 3012, Second return flow channel. 4. Conductive busbar. Detailed Implementation

[0012] This invention discloses a battery pack that improves the heat exchange uniformity between individual battery cells and the battery pack, increases the heat exchange efficiency of the batteries, and extends the cycle life of the battery pack.

[0013] The present invention also discloses an electrical device.

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] A battery pack comprises a battery array consisting of multiple battery cells connected in series and / or parallel, 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 battery enclosure and sealed with a top plate, 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.

[0016] A battery cell can store chemical energy and controllably convert it into electrical energy. In recyclable battery cells, the active materials can be reactivated by charging after discharge, allowing for continued use. A battery cell includes a casing and a battery cell housed within the casing.

[0017] The battery enclosure refers to a closed or semi-closed structure made of materials such as metal and plastic. It is the physical carrier of the battery pack, and its design and manufacturing must meet the safety, reliability and functionality requirements of the battery pack in different usage scenarios.

[0018] A battery pack is formed by connecting multiple battery cells with similar capacity and internal resistance in series or in parallel.

[0019] The battery enclosure provides installation space for the battery pack, BMS, cooling system, electrical connection components, etc., and through a reasonable structural design, fixes these components inside the battery enclosure, ensuring that they maintain a relatively stable position during battery pack operation and preventing damage to components or loosening of connections due to vibration, impact, or other factors. The battery enclosure of a battery pack generally includes a frame, a bottom plate, and a top plate. The four frames surrounding the bottom plate can be integrally formed with the bottom plate or manufactured separately and fixedly connected. The battery enclosure can be cast from materials such as steel plate and aluminum alloy, or lightweight materials such as glass fiber reinforced composite materials and carbon fiber reinforced composite materials. The shape of the battery enclosure can be cylindrical, cuboid, cube, etc.

[0020] The base plate is the main load-bearing component of the battery pack, typically referring to the structural member installed at the bottom of the battery pack. It supports and secures the internal battery pack components such as the battery assembly, battery management system, and cooling system. The base plate is located at the bottom of the casing frame, for example, by welding, riveting, or screwing. The base plate can be made of various materials, such as high-strength materials like aluminum alloy, steel, and stainless steel. It can be rectangular, circular, polygonal, or have a plate-like structure; there are no specific limitations, and its dimensions are determined by the number and size of the battery cells housed in the battery pack.

[0021] The frame is the structural framework of the box, serving a supporting, protective, and connecting function. The frame can be formed by splicing together multiple beams. In existing technologies, the frame typically includes four sub-side frame panels, which are joined end-to-end to form an enclosed space. This enclosed space is then sealed by a top and bottom plate to form a cavity. The frame can be made of various materials, such as aluminum alloy, copper alloy, steel, and plastic. The frame can be rectangular, circular, polygonal, etc., with no specific limitations. The interior of the frame can be a solid structure or contain hollow cavities.

[0022] The top plate encapsulates the battery pack within its enclosure, isolating it from the outside environment and preventing external moisture and dust from affecting the battery module. The top plate can be made of non-metallic materials, such as any polymer compound used as a raw material in plastics processing (referred to as resin). Commonly used resins include polyphenylene sulfide resin (PPS), polyphenylene oxide resin (PPO), and polypropylene resin (PP). Alternatively, composite materials including reinforcing agents and resins can be used; common reinforcing agents include glass fiber, carbon fiber, and graphite fiber. Metallic materials such as iron, aluminum, aluminum alloys, iron alloys, and stainless steel can also be used. The top plate can be in various shapes, such as a cuboid, depending on the specific requirements.

[0023] To adjust the temperature of the individual battery cells, a heat exchange plate is installed inside the housing for regulating the temperature of the individual cells. The heat exchange plate has internal heat exchange channels for the flow of the heat exchange medium. The heat exchange 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 channels have inlets and outlets for the heat exchange medium. The heat exchange medium enters the heat exchange channel through the inlet, exchanges heat with the individual battery cells, and then exits through the outlet, thus achieving heat exchange between the individual battery cells.

[0024] The busbar is the "main artery" of the internal electrical connections of a power battery pack, used to electrically connect multiple battery packs, enabling series and parallel connections. It can electrically connect the output terminals of the battery packs to the output terminals of the battery stack. Busbars can be made of materials such as aluminum, aluminum alloy, copper, and gold. A busbar typically consists of a flat strip or bar-shaped conductive body, connecting terminals at both ends, and an insulating protective layer covering the conductive body. In some flexible applications, multi-layer copper foil laminations or copper braided strips are used instead of a rigid body to absorb cell expansion displacement. The entire busbar is fixed to the terminals via laser welding / ultrasonic welding / bolt locking, achieving low-resistance, reliable, and short-circuit-proof current connection.

[0025] Research has found that lithium plating in batteries is caused by the different degrees of heat exchange at different locations within the battery cell. In existing battery packs, the upper and lower cold plates are opposite to the end faces of the terminals and non-terminals, respectively. The heat transfer paths between the cold plates and the top and bottom of the battery cells differ. At the terminal end, the distance between the cold plate and the cell electrode is relatively large, resulting in a significant temperature difference at different locations within the cell. The temperature difference between the top and bottom of the battery cell leads to a decrease in capacity retention during long-term cycling, further causing lithium plating on the battery cell electrodes and resulting in overlap between the positive and negative electrodes, thus affecting the battery's cycle life.

[0026] See Figures 1 to 18 The battery pack of the present invention includes a housing 1 and at least two battery packs 2 disposed within the housing 1. The at least two battery packs 2 are arranged in layers along a first direction. A partition 3 is provided between adjacent battery packs 2 along the first direction to separate the battery packs 2 in the height direction. A baffle is provided on the side of the battery pack 2 away from the partition 3 to directly support the bottom surface of the bottom battery pack 2 and to seal the top of the top battery pack 2. The housing 1 includes a frame 101, a bottom plate 102, and a top plate 103. The battery packs 2 are placed in the receiving cavity enclosed by the frame 101, the bottom plate 102, and the top plate 103. The baffle includes the bottom plate 102 and the top plate 103, and the first direction is perpendicular to the large surface direction of the bottom plate 102. The bottom plate 102 is used to directly support the bottom surface of the bottom battery pack 2 and to indirectly support the other layers of battery packs 2. The top plate 103 seals the top opening of the frame 101. The frame structure with openings at both the bottom and top of the frame 101 is a base plate 102 connected to the bottom opening of the frame 101 by laser welding or adhesive and screw fixation; the top plate 103 covers the top opening of the frame 101 and is sealed and fixed by sealing rings and bolts or laser welding. The base plate 102 and the top plate 103 are not directly connected, but form a closed box structure with the frame 101 as the intermediate skeleton.

[0027] The battery pack 2 includes multiple battery cells 201. These battery cells 201 are arranged in the same layer along a second direction, which is the length direction of the partition plate 3 and is perpendicular to the large surface of the battery cell 201. Each battery cell 201 includes a housing and an electrode post 2011 disposed on the housing. The electrode post 2011 is disposed on a first side surface 2012 of the housing, which is perpendicular to the bottom plate 102. The housing 1 also includes a first side plate 104, which is perpendicular to the bottom plate 102 and parallel to the first side surface 2012. Along the direction perpendicular to the large surface of the first side plate 104, the orthographic projection of the multi-layer battery pack 2 at least partially coincides with the large surface of the first side plate 104, which is the surface with the largest area of ​​the first side plate 104. Each of the partition plate 3, bottom plate 102, top plate 103, and first side plate 104 is provided with a heat exchange channel for accommodating the heat exchange medium. The battery cell 201 is directly or indirectly connected to the adjacent baffle, partition plate 3, and first side plate 104 for heat exchange. Preferably, the battery cell 201 is connected to the baffle, partition plate 3, and first side plate 104 for heat exchange by filling with thermally conductive adhesive. The thermally conductive adhesive is an organosilicon thermally conductive gel with a thermal conductivity of not less than 2.0 W / (m·K). After curing, it becomes a flexible elastomer, which can effectively fill gaps, remove air, adapt to battery expansion and deformation, and stably transfer heat to the heat exchange channel.

[0028] Wherein, the first direction is the Z direction in the figure, the second direction is the X direction in the figure, and the first direction is perpendicular to the second direction. The large surface of the battery cell 201 is the largest surface in the battery casing. The large surface of the first side plate 104 is heat-exchange connected to the battery cell 201. The first side plate 104 is fixedly connected to the frame 101 at least at two ends along the second direction. The battery cells 201 of the bottom battery pack 2 are heat-exchange connected to the bottom plate 102, the partition plate 3, and the first side plate 104; the battery cells 201 of the top battery pack 2 are heat-exchange connected to the top plate 103, the partition plate 3, and the first side plate 104; the battery cells 201 of the battery packs 2 located in other layers are heat-exchange connected to the two partition plates 3 arranged above and below. When the length of the same layer of the housing 1 is long, a structural reinforcing plate 105 can be set in the middle of the same layer, and two battery packs 2 can be set in the same layer to improve the support strength and ensure the structural reliability of the housing 1. The frame 101 includes four frame plates. The housing is a component used to provide a receiving space to house electrode assemblies and other components and isolate them from the outside. The housing generally includes a body with an opening at at least one end and a receiving cavity. The opening of the housing can be closed by a cover plate to seal and isolate the internal environment of the battery cell from the external environment. The materials of the housing include, but are not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, and aluminum-plastic film. The terminals are used to electrically connect the electrode assembly located inside the housing to external devices (adjacent batteries or other electrical equipment) located outside the housing. The battery can discharge to external devices through the cell output terminal (tab) and the external device output terminal (terminal). An external power source can charge the battery through the terminal assembly and the tab. The terminals can be directly electrically connected to the cell tab or electrically connected to the tab through a metal adapter. The materials of the terminals include, but are not limited to, metals such as copper, aluminum, aluminum alloy, and copper-aluminum alloy.

[0029] The battery pack of the present invention, through a multi-layer battery pack arranged along the height direction, with multiple batteries in each layer arranged in a direction perpendicular to the large surface of the battery, improves the overall energy density of the battery pack. Furthermore, heat exchange plates are provided at the top and bottom of at least one layer of the battery pack, with heat exchange channels inside the heat exchange plates containing heat exchange medium, increasing the heat exchange area of ​​the battery, improving the heat exchange rate of the battery, and further shortening the battery charging time. Simultaneously, by setting the terminal posts 2011 of the battery cells 201 on the first side surface 2012 perpendicular to the base plate 102, the cooling of the top and bottom of the battery casing by the cold plates at the top and bottom of the battery pack is uniform, reducing the temperature difference at different locations of the battery cells 201. This allows for a balanced coverage area of ​​the heat exchange structure on the top and bottom surfaces of the battery pack 2, while also increasing the effective heat exchange area of ​​the battery casing, improving the uniformity of heat exchange on the battery cells 201, and further avoiding the occupation of the top space of the terminal posts 2011 on the top surface of the battery cells 201, reserving sufficient space for the heat exchange structure on the top surface of the battery cells 201. Simultaneously, a first side plate 104 parallel to the first side surface 2012 is provided, and a flow channel for accommodating the heat exchange medium is also provided within the first side plate 104, thereby achieving heat exchange on the side of the battery cell 201 perpendicular to the bottom plate 102. At least three surfaces of the battery casing are heat-exchange connected to the cold plate, improving the heat exchange rate of the battery casing. The first side plate and all batteries in the single-layer battery pack are in heat-exchange contact, further improving the uniform heat exchange of multiple battery components within the battery pack. The above arrangement ensures that all batteries in the same layer of the battery pack are heat-exchange connected to the separator, bottom plate, top plate, and first side plate respectively, guaranteeing uniform cooling of multiple surfaces of the battery. The battery pack of the present invention effectively improves the temperature difference distribution of the battery cell 201 along the first direction, reduces the risk of lithium plating caused by local overcooling or uneven heat dissipation, ensures that the multi-layer battery pack 2 stacked along the height direction can obtain a uniform cooling effect, eliminates the heat exchange imbalance between different battery packs 2, improves the overall temperature uniformity of the battery pack, and extends the cycle life of the battery pack.

[0030] The heat exchange channels within the partition plate 3, bottom plate 102, top plate 103, and first side plate 104 can be connected in series or in parallel, depending on the specific needs of the technicians. In an optional embodiment, the heat exchange channel within the first side plate 104 is provided with a separate first liquid inlet and a first liquid outlet. The bottom plate 102, partition plate 3, and top plate 103 are provided with a shared second liquid inlet and second liquid outlet. The second liquid inlet is connected to the corresponding branch liquid inlets of the bottom plate 102, partition plate 3, and top plate 103, and the corresponding branch liquid outlets of the bottom plate 102, partition plate 3, and top plate 103 are connected to the second liquid outlet. The first liquid inlet and the second liquid inlet are connected to the main liquid inlet, and the first liquid outlet and the second liquid outlet are connected to the main liquid outlet. The heat exchange fluid of the main liquid inlet flows into the first liquid inlet and the second liquid inlet. The heat exchange fluid of the first liquid inlet flows to the first liquid outlet through the heat exchange channel of the first side plate 104. The heat exchange fluid of the second liquid inlet flows to the second liquid outlet through the heat exchange channel of the bottom plate 102, the partition plate 3 and the top plate 103.

[0031] To facilitate heat exchange in the multi-layered battery pack 2, a first side plate 104 is disposed at one end of the partition plate 3 along a third direction, which is perpendicular to the first and second directions. The first side plate 104, located at the end of the partition plate 3, provides support and positioning for the layered partition plate 3, improving the overall structural strength of the housing 1. It also facilitates the arrangement of cooling channels and uniform heat exchange across multiple layers, which is beneficial for assembly and the layout of electrical components. The third direction is the Y-direction in the figure. The first, second, and third directions are mutually perpendicular.

[0032] To improve ease of setup and ensure safety, the battery cell 201 includes a second side surface 2013, which is positioned opposite to the first side surface 2012. A first side plate 104 is positioned close to the second side surface 2013, and the second side surface 2013 is heat-exchange connected to the first side plate 104. In this embodiment, the terminal post 2011 is only located on the first side surface 2012, and the second side surface 2013 can be a non-terminal surface of the battery cell 201. Since the first side plate 104 is connected to the non-terminal surface of the battery cell 201, it avoids the busbar and sampling harness arrangement area on the terminal post side, reducing the risk of interference or short circuit between the side plate and high-voltage live components, and simplifying the insulation design. At the same time, since the structure does not need to avoid the terminal post 2011, the effective heat exchange area of ​​the first side plate 104 is increased, and the first side plate 104 does not conflict with the setting of other heat exchange surfaces of the battery cell 201, facilitating assembly.

[0033] In one embodiment, a first flow channel 1041 for accommodating heat exchange medium is provided within the first side plate 104, such as... Figure 8 and Figure 9As shown, multiple first flow channels 1041 are provided, with different first flow channels 1041 spaced apart along a first direction, and the first flow channels 1041 extending along a second direction. Since the second direction is the arrangement direction of the multiple battery cells 201 of the battery pack 2, the first flow channels 1041 extend along the second direction, making the arrangement direction of the battery cells 201 consistent. Thus, a single first flow channel 1041 can uniformly cool the non-polar surfaces of all battery cells 201 in the entire layer or even multiple layers, improving the coverage and consistency of side heat exchange, and helping to reduce the temperature difference of the battery pack 2 along the second direction. The first flow channels 1041 are arranged along the second direction, therefore the first flow channels 1041 are straight flow channels, which can shorten the flow path of the coolant, reduce the temperature rise along the path, and improve the heat exchange uniformity of the battery pack 2 in the same layer.

[0034] To improve heat transfer uniformity, the first flow channel 1041 includes multiple first liquid inlet channels 10411, such as... Figure 9 As shown, the first liquid inlet channel 10411 is used to communicate with the liquid inlet 1043 of the first side plate 104. At least two battery packs 2 are respectively arranged opposite to at least one first liquid inlet channel 10411, so that the first liquid inlet channel 10411 can cover multiple battery packs 2, realize uniform heat exchange between battery packs 2, and avoid a battery pack 2 being concentrated opposite to the return liquid channel, which would cause the temperature of the battery pack 2 to rise faster and the temperature difference with other battery packs 2 to be large. The liquid temperature of the first liquid inlet channel 10411 is low. When it flows from the liquid inlet channel to the liquid outlet channel, the heat exchange medium is heated because it cools the battery cell 201, resulting in poor cooling effect on the battery.

[0035] The number of first liquid inlet channels 10411 corresponding to each layer of battery pack 2 is the same. Multiple first liquid inlet channels 10411 are configured, and the number of first liquid inlet channels 10411 corresponding to each layer of battery pack 2 is the same. This enables equal distribution of coolant flow among multiple layers of battery pack 2, ensuring uniform lateral heat exchange for each layer of battery pack 2, effectively eliminating heat exchange differences between different battery packs 2, improving heat exchange uniformity among battery packs 2, and thus improving the overall cycle life of the battery pack. Furthermore, the multiple liquid inlet channels are arranged parallel to each other along the second direction, shortening the coolant flow path, reducing temperature rise along the path, and improving the heat exchange uniformity of the same layer of battery pack 2.

[0036] Furthermore, the first flow channel 1041 also includes multiple first return flow channels 10412. The number of first return flow channels 10412 corresponding to each layer of battery pack 2 is the same, and the first return flow channels 10412 are connected to the first inlet flow channels 10411. The first flow channel 1041 is provided with multiple first return flow channels 10412 to ensure that the number of return flow channels corresponding to each layer of battery pack 2 is consistent. The aforementioned equal number of first inlet flow channels 10411 and first return flow channels 10412 form a side heat exchange loop with equal amount of liquid inlet and equal amount of liquid return, so that the flow distribution of the first side plate 104 to the multi-layer battery pack 2 is balanced, eliminating the heat exchange difference between layers. The parallel arrangement of multiple return flow channels effectively reduces the pressure drop along the return side and shortens the residence time of the high-temperature coolant in the flow channel.

[0037] In one embodiment, to improve heat exchange uniformity, a liquid inlet 1043 and a liquid outlet 1044 are provided on the first side plate 104, and the liquid inlet 1043 and the liquid outlet 1044 are located at the same end of the first side plate 104 along the second direction. The fact that the liquid inlet 1043 and the liquid outlet 1044 are located at the same end can effectively optimize the internal flow field distribution and ensure the heat exchange uniformity among the multi-layer battery packs 2. The centralized arrangement of the liquid inlet 1043 and the liquid outlet 1044 at the same end of the housing 1 simplifies the pipeline routing and vehicle interface settings, and improves the integration and assembly efficiency of the battery pack.

[0038] When the inlet 1043 and outlet 1044 are welded to the same end of the first side plate 104, the welding stress and thermal stress at this end are relatively large. To reduce the impact of stress on the warping or deformation of the first side plate 104, it is necessary to limit the height of the first side plate 104 along the first direction. The height of the first side plate 104 along the first direction is positively correlated with the height of the housing 1. Therefore, limiting the height of the housing 1 reduces the risk of deformation of the first side plate 104. Specifically, the height of the housing 1 along the first direction ranges from 80 to 500 mm, and can be any value among 80 mm, 100 mm, 150 mm, 210 mm, 260 mm, 300 mm, 350 mm, 400 mm, 450 mm, and 500 mm, or a value between any two values. Setting the height of the housing 1 within the above range can achieve a balance between heat exchange performance and structural strength, avoiding insufficient heat exchange due to excessive height or deformation and cost problems due to excessive height.

[0039] In another embodiment, the first side plate 104 is provided with an inlet 1043 and an outlet 1044, which are located at both ends of the first side plate 104 along the second direction. In this embodiment, by setting the inlet 1043 and outlet 1044 at both ends of the first side plate 104, the flow rate distribution of the cooling medium in the flow channel is more uniform, dead zones and eddies are less likely to occur, and the accumulation of thermal deformation caused by dense welding on the same side is avoided, thus reducing welding stress. In order to reduce the temperature difference between the heat exchange medium at the inlet 1043 and the outlet 1044 to improve the uniformity of heat exchange to the battery cells 201 in the battery pack 2, the length of the first side plate 104 along the second direction cannot be too long. Since the length of the first side plate 104 is related to the length of the housing 1, the length of the housing 1 is limited, and the length of the first side plate 104 can be determined accordingly. Specifically, along the second direction, the length of the housing 1 ranges from 200 to 1500 mm, specifically any value among 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, 1100 mm, 1200 mm, 1300 mm, 1400 mm, and 1500 mm, or between any two values. By limiting the length of the housing 1 within the above range, the flow path length of the heat exchange medium within the first side plate 104 can be effectively controlled, avoiding excessive temperature rise of the heat exchange medium after flowing through the entire path due to excessively long flow channels. This reduces the temperature difference between the inlet and outlet, helping to make the heat exchange conditions of each battery cell 201 in the battery pack 2 more consistent at different locations, improving the uniformity of the overall temperature field, and extending battery life.

[0040] To improve the heat exchange efficiency of each layer of battery pack 2, the battery cell 201 includes a second side 2013, which is arranged parallel to the first side 2012 and is heat-exchangeably connected to at least two first flow channels 1041. The second side 2013 of the battery cell 201 is simultaneously heat-exchangeably connected to multiple first flow channels 1041, increasing the effective heat exchange area of ​​the battery, improving heat exchange capacity, mitigating the internal temperature gradient of the battery cell 201, and reducing the temperature difference along the first direction of the battery cell 201. This reduces the risk of lithium plating in the battery cell 201 due to localized overcooling or overheating.

[0041] In this configuration, a partition rib 1042 is provided between adjacent first flow channels 1041, and at least a portion of the partition ribs 1042 form an acute angle α with the surface of the first side plate 104 near the battery cell 201. Figure 8The aforementioned separation ribs 1042 are not horizontally arranged, forming an inclined support structure, which improves the overall rigidity and deformation resistance of the first side plate 104. As an alternative, the separation ribs 1042 are all arranged perpendicularly to the surface of the first side plate 104 near the battery cell 201, so that the separation ribs 1042 are parallel to the thickness direction of the first side plate 104, reducing the processing difficulty of the first side plate 104 and its internal flow channels.

[0042] To improve heat exchange efficiency, the orthographic projections of multiple battery packs 2 are located within the large surface of the first side plate 104 along the direction perpendicular to the large surface of the first side plate 104. That is, the projections of the battery packs 2 on the large surface of the first side plate 104 fall completely within the large surface of the first side plate 104. This includes cases where the area of ​​the orthographic projections of the multiple battery packs 2 is the same as the area of ​​the large surface of the first side plate 104, and cases where the area of ​​the large surface of the first side plate 104 is larger than the area of ​​the orthographic projections of the multiple battery packs 2. This ensures that the first side plate 104 can fully exchange heat with the battery packs 2 and increases the heat exchange area of ​​the first side plate 104.

[0043] To ensure the structural stability of the battery pack 2, the battery pack 2 near the base plate 102 is fixedly connected to the base plate 102. Each battery cell 201 includes a second side 2013 opposite to the first side 2012, and the first side plate 104 is heat-exchange connected to the second side 2013. For example... Figure 10As shown, along the first direction, the distance between the terminal post 2011 near the base plate 102 and the base plate 102 is H1 mm. The ratio of the total heat exchange surface area of ​​a single battery cell 201 to the total area of ​​the casing is K, and H1 / K ranges from 81.25 to 700. Specifically, it can be any value among 81.25, 104.00, 125, 130, 150, 207.86, 217.27, 231.25, 292.86, 377.78, 380, 398, 406, 440, 462, 500, 600, 631.43, 650, and 700, or a value between any two values. The terminal post 2011 of the bottommost battery pack 2, which is closest to the base plate 102, has the greatest risk of contact with condensate on the base plate 102. If the terminal post 2011 comes into contact with condensate, there is a safety risk of short circuit. The larger the total area of ​​the heat exchange surface of the battery cell 201 relative to the total area of ​​the battery cell 201, the more condensate is generated. With more condensate, a larger distance is needed between the terminal post 2011 and the base plate 102 to reduce the risk of short circuits. Therefore, the value of H1 / K is limited to ensure that the value of H1 meets safety requirements. Setting the value of H1 / K within the above range satisfies the requirements of the battery's overcurrent area, ensuring the charging rate and cycle life of the battery pack 2, while also reducing the risk of short circuits. If the value of H1 / K is too large, the value of H1 will be too large, or the value of K will be too small. If the value of H1 is too large, the area of ​​the terminal post 2011 will be reduced to avoid affecting the arrangement of other structures, thus narrowing the overcurrent area, concentrating heat generation in the battery, and affecting the charging rate and cycle life of the battery. If the value of K is too small, it will affect the heat exchange efficiency of the battery cell 201. If the value of H1 / K is too small, the value of H1 will be too small, or the value of K will be too large, which will easily lead to the accumulation of condensate at the bottom of the housing 1. The pole 2011 will easily come into contact with the condensate, causing a short circuit and poor safety.

[0044] Specifically, H1mm ranges from 12 to 50 mm, and can be any value from 12 mm, 15.6 mm, 18.5 mm, 20 mm, 23.9 mm, 29.1 mm, 34.2 mm, 39.8 mm, 41.0 mm, 44.2 mm, and 50 mm, or a value between any two of these values. Setting H1mm within this range reduces the risk of contact between the terminal 2011 and the condensate accumulated on the base plate 102, reducing the risk of short circuits, meeting the current-carrying area requirements of the battery terminals, and ensuring the battery's charging rate and cycle life. If the value of H1 is too large, the area of ​​the terminal 2011 decreases, resulting in a small current-carrying area, concentrated heat generation in the battery, and affecting the battery's charging rate and cycle life. If the value of H1 is too small, the risk of the terminal 2011 contacting condensate is high, leading to poor safety. The value of K ranges from 0.07 to 0.15, specifically any value from 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, and 0.15, or a value between any two of these values. Setting K within this range ensures adequate heat exchange for the battery while preventing excessive condensation. If K is too large, the heat exchange area of ​​the battery cell 201 is large, leading to excessive condensation buildup and increased risks of insulation and corrosion. If K is too small, insufficient heat dissipation results in rapid temperature rise and an increased risk of thermal runaway.

[0045] To collect and output the current from the battery cells 201, the battery pack also includes a conductive bus 4, which electrically connects at least two terminals 2011 of adjacent battery cells 201. In one specific embodiment, as... Figure 11 As shown, along the first direction, the distance between the bottom end of the conductive busbar 4 and the base plate 102 is greater than or equal to the distance between the terminal post 2011 near the base plate 102 and the base plate 102. Therefore, as long as the above-mentioned value range of H1mm is met, the risk of short circuit between the conductive busbar 4 and the condensate water can be avoided. In another specific embodiment, as... Figure 12 As shown, along the first direction, the distance between the bottom end of the conductive busbar 4 and the base plate 102 is less than the distance between the pole post 2011 near the base plate 102 and the base plate 102. In this embodiment, along the first direction, the bottom end of the conductive busbar 4 protrudes beyond the bottom end of the pole post 2011. Further control of the value of H1 is needed to meet the insulation requirements of the conductive busbar 4. In this embodiment, the range of H1mm is 22~50mm, specifically any value from 22mm, 23.9mm, 29.1mm, 34.2mm, 36mm, 39.8mm, 41.0mm, 44.2mm, 50mm, or any value between any two. The conductive busbar 4 is fixedly connected to the pole post 2011 by welding, riveting, or bonding.

[0046] Furthermore, the distance between the conductive busbar 4 and the base plate 102 ranges from 3 to 20 mm, specifically any value among 3 mm, 5 mm, 7.5 mm, 9 mm, 11 mm, 13 mm, 15 mm, 17.5 mm, and 20 mm, or a value between any two of these values. Setting the distance between the conductive busbar 4 and the base plate 102 within the aforementioned range allows for a shorter heat dissipation path from the pole post 2011 to the base plate 102, while ensuring sufficient electrical insulation and mitigating the risk of short circuits and breakdowns. This maximizes the cooling efficiency at the bottom to suppress localized overheating of the conductive busbar 4 and the pole post 2011, resulting in a compact structure, strong vibration resistance, and space for condensate accumulation.

[0047] To ensure the insulation performance of the bottom of the conductive busbar 4, an insulating layer (not shown in the figure) is wrapped around the end of the conductive busbar 4 near the base plate 102. The insulating layer at the bottom of the conductive busbar 4 effectively ensures electrical isolation between it and the base plate 102 and surrounding metal components, preventing short circuits and electrical breakdowns caused by distance fluctuations or foreign object intrusion. It also blocks leakage current paths formed through the base plate, reduces the risk of contact with condensate, and improves insulation performance and safety. The insulating layer is formed on the surface of the conductive busbar 4 by injection molding or heat-shrink tubing followed by heat fusion fixation. The material is selected from flame-retardant polyvinyl chloride (PVC), cross-linked polyolefin, or epoxy resin. The insulating layer extends upwards from the end of the conductive busbar 4 near the base plate 102 along the body of the conductive busbar 4 away from the base plate 102. A gap is left between the upper boundary of the insulating layer and the welding area between the conductive busbar 4 and the electrode post 2011 to ensure that the welding area is not covered by the insulating layer and does not affect the welding connection between the conductive busbar 4 and the electrode post 2011. The insulation layer has a thickness of 0.3~2mm, specifically any value from 0.3mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.7mm, 2mm, or any value between any two. Setting the insulation layer thickness within this range satisfies the creepage distance and insulation withstand voltage requirements of the base plate while avoiding assembly interference caused by an excessively thick insulation layer.

[0048] The electrode post 2011 includes a positive electrode post and a negative electrode post, both of which can be disposed on the first side surface 2012, and are spaced apart along a first direction. Since the first side plate 104 is heat-exchange connected to the opposite side surface 2012 of the first side surface of the battery cell 201, the heat exchange area does not need to avoid the electrode post, thus increasing the heat exchange area of ​​the battery cell 201. To reduce condensation, the range of K needs to be further narrowed. Specifically, K ranges from 0.07 to 0.13, and can be any value from 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, or a value between any two values.

[0049] In other embodiments, the positive and negative terminals are disposed on two opposite sides of the battery cell 201, that is, one of the positive and negative terminals is disposed on the first side 2012, and the other is disposed on the second side 2013 opposite to the first side 2012. The first side 2012 and the second side 2013 are respectively disposed at both ends of the battery cell 201 along a third direction. Two first side plates 104 are provided, and the two first side plates 104 are respectively disposed at both ends of the separator 3 along a third direction. One first side plate 104 is heat-exchange connected to the first side 2012, and the other first side plate 104 is heat-exchange connected to the second side 2013, thereby achieving uniform heat exchange on the two opposite sides of the battery cell 201 along a third direction.

[0050] Because the high-temperature gas generated inside the battery cell 201 tends to accumulate at the top and bottom of the casing, to improve heat dissipation efficiency, the surface of the casing used for heat exchange connection with the partition plate 3 or baffle is designated as a first end face, and the area of ​​the first end face is larger than the area of ​​the first side surface 2012. The first end face consists of two end faces of the battery cell 201 arranged opposite each other along a first direction. Setting the area of ​​the first end face to be larger facilitates improved heat exchange between the heat exchange structure and the first end face of the battery cell 201, thereby meeting the high heat exchange requirements of the areas where high-temperature gas accumulates inside the casing of the battery cell 201. The baffle includes a bottom plate 102 or a top plate 103. When the battery cell 201 is located at the bottom layer, one of the two first end faces of the battery cell 201 is heat-connected to the bottom plate 102, and the other is heat-connected to the partition plate 3. When the battery cell 201 is located at the top layer, one of the two first end faces of the battery cell 201 is heat-connected to the top plate 103, and the other is heat-connected to the partition plate 3.

[0051] Furthermore, to improve the overall structural strength of the battery pack, the length direction of the first end face is perpendicular to the length direction of the partition plate 3. This structural configuration uses the battery cell 201 as a transverse support beam, shortening the span and reducing the flexural deformation of the base plate 102 in the vehicle's driving direction, thereby improving the structural strength and bending stiffness of the battery pack.

[0052] To improve the volumetric energy density of the battery pack, the battery assembly 2 has at least three layers, resulting in at least two separator plates 3. To enhance heat exchange uniformity, the flow channels within different separator plates 3 have equal cross-sectional areas, ensuring consistent heat exchange across different layers of the battery assembly 2. This effectively suppresses system temperature differences, improves thermal management stability, and facilitates the design, manufacturing, and verification of the flow channels, reducing performance fluctuations and development costs caused by individual differences. In other embodiments, the flow channels within different separator plates 3 may have unequal cross-sectional areas to meet the varying heat exchange requirements at different locations within the battery.

[0053] Specifically, the partition plate 3 is provided with a second flow channel 301 to accommodate the heat exchange medium, such as... Figures 13 to 15 The extension direction of the second flow channel 301 is parallel to the second direction. The second flow channel 301 extends along the second direction, aligning with the arrangement direction of the battery cells 201. This allows a single second flow channel 301 to uniformly cool all battery cells 201 in the entire layer, improving heat exchange coverage and consistency, and helping to reduce the temperature difference of the battery pack 2 in the same layer along the second direction. Because the second flow channel 301 extends along the second direction, it is a straight flow channel, which shortens the coolant flow path, reduces temperature rise along the flow path, and improves the heat exchange uniformity of the battery pack 2 in the same layer. In one embodiment, as... Figure 15 As shown, the second flow channel 301 includes a second liquid inlet flow channel 3011 and a second liquid return flow channel 3012. One end of the second liquid inlet flow channel 3011 is connected to the liquid inlet (not shown) of the second flow channel 301, and the other end is connected to the second liquid return flow channel 3012. The end of the second liquid return flow channel 3012 away from the second liquid inlet flow channel 3011 is connected to the liquid outlet of the second flow channel 301. In another embodiment, a cooling structure with liquid inlet at one end and liquid outlet at the other end of the second flow channel 301 can also be used.

[0054] Similarly, the base plate 102 is provided with a third flow channel 1021 for accommodating the heat exchange medium, such as... Figure 16 and Figure 17 The extension direction of the third flow channel 1021 is parallel to the second direction. In one embodiment, the third flow channel 1021 includes a third liquid inlet flow channel 10211 and a third liquid return flow channel 10212 that are connected in series. It is understood that the beginnings of the third liquid inlet flow channel 10211 and the third liquid return flow channel 10212 are connected. In another embodiment, liquid enters at one end of the third flow channel 1021 and exits at the other end. A fourth flow channel 1031 for accommodating the heat exchange medium is provided inside the top plate 103, such as... Figure 18 The extension direction of the fourth flow channel 1031 is parallel to the second direction. Figure 18In this embodiment, the fourth flow channel 1031 has a liquid inlet at one end and a liquid outlet at the other. In other embodiments, it may also include an inlet flow channel and a return flow channel, which will not be described in detail here. Since the base plate 102 is the supporting structure for all battery packs 2, in a preferred embodiment, the thickness of the base plate 102 is greater than the thickness of the separator plate 3 to improve the support strength and reliability. The thickness of the base plate 102 ranges from 5 to 40 mm, specifically any value from 5 mm, 10 mm, 15 mm, 20 mm, 25.5 mm, 30 mm, 33 mm, 35 mm, 40 mm, or any value between any two values. Setting the thickness of the base plate 102 within the above range can effectively control its weight and optimize the utilization of internal space while ensuring that the base plate 102 has sufficient load-bearing rigidity and deformation resistance, and achieve the best balance between lightweighting, cost, and process feasibility. If the thickness of the base plate 102 is too small, it will result in insufficient rigidity, making it prone to deformation, weak protection, and easy sealing failure, and it will also be detrimental to the processing of heat exchange channels. If the thickness of the base plate 102 is too large, it will increase the weight of the battery pack, reduce the range, compress the internal space of the battery pack, and increase costs. The thickness of the separator 3 is in the range of 3~40mm, specifically any value of 3mm, 10mm, 15mm, 20mm, 25mm, 30mm, 33mm, 35mm, 40mm, or any value between any two values. In other embodiments, the thickness of the base plate 102 may also be less than the thickness of the separator 3.

[0055] Since the separator 3 needs to exchange heat with its two adjacent battery packs 2, while the base plate 102 only needs to exchange heat with the battery pack 2 connected to it, the flow cross-sectional area of ​​the flow channel in the separator 3 is larger than that of the flow channel in the base plate 102 to meet the higher heat exchange requirements of the separator 3. Preferably, the height of the second flow channel 301 in the separator 3 along the first direction is greater than the height of the third flow channel 1021 in the base plate 102 along the first direction, and the width of the second flow channel 301 along the third direction is also greater than the width of the third flow channel 1021 along the third direction, so that the flow resistance of the second flow channel 301 is also less than that of the third flow channel 1021, further improving the heat exchange efficiency of the separator 3.

[0056] To improve the positional reliability of the battery pack 2 within the battery pack, the bottom plate 102 is bonded to the battery pack 2 via a first adhesive layer, the partition plate 3 is connected to the battery pack 2 via a second adhesive layer, and the top plate 103 is bonded to the battery pack 2 via a third adhesive layer. The sides, top, and bottom of the partition plate 3 are all fixedly connected to the housing 1. It is understood that the first, second, and third adhesive layers are all thermally conductive adhesives. By bonding the battery pack 2 to adjacent plates, the overall structural rigidity and vibration resistance of the battery pack are enhanced, preventing relative displacement and shaking of the individual battery cells 201 under complex operating conditions. Simultaneously, the bonding interface has high thermal conductivity, reducing contact thermal resistance and improving the rapid conduction of heat from the battery pack 2 to the channels within the partition plate 3, bottom plate 102, or top plate 103, thereby improving heat exchange efficiency and uniformity.

[0057] Because the separator 3 needs to have better heat dissipation efficiency to achieve good heat exchange between the battery packs 2 on both sides, the thickness of the second adhesive layer is less than the thickness of the first adhesive layer and also less than the thickness of the third adhesive layer. This reduces the impact of the adhesive layers on thermal conductivity, thereby making the thermal conductivity of the separator 3 higher. The material of each adhesive layer is either epoxy structural adhesive or silicone thermally conductive adhesive.

[0058] To ensure thermal conductivity and bonding strength of the battery pack 2, the thickness of the first, second, or third adhesive layer ranges from 0.5 to 3 mm. Specifically, it can be any value from 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 1.8 mm, 2.2 mm, 2.5 mm, 2.8 mm, or 3 mm, or a value between any two of these values. Setting the adhesive layer thickness within this range ensures the bonding strength of the battery pack 2, effectively absorbing manufacturing tolerances and flatness deviations between the battery cell 201 and the base plate 102 and separator plate 3. This avoids localized loose adhesion or stress concentration, prevents displacement or debonding of the battery cell 201, and prevents excessively thick adhesive layers from affecting heat exchange, thus ensuring heat exchange efficiency.

[0059] In one specific embodiment, reference is made to Figures 1-3The battery pack 2 has three layers along the first direction. The orthographic projection of the three battery pack layers 2 along the direction perpendicular to the large surface of the first side plate 104 lies within the large surface area of ​​the first side plate 104. This means that the side of the individual battery cell 201 closest to the first side plate 104 is completely connected to the first side plate 104 for heat exchange, thereby improving heat exchange efficiency and ensuring uniform and reliable heat exchange between different layers of the battery pack 2, resulting in better heat exchange performance. Specifically, the length of the housing 1 along the second direction ranges from 200 to 1500 mm, specifically any value from 200 mm, 300 mm, 450 mm, 500 mm, 600 mm, 750 mm, 900 mm, 1100 mm, 1300 mm, 1500 mm, or any value between any two values. The length of the housing 1 is set within the above range, which reduces the bending span of the housing 1 in the length direction, improves the overall structural rigidity, reduces the stress level and fatigue failure risk of the bottom plate 102 and the partition plate 3, and can achieve better flow channel layout and thermal management uniformity.

[0060] In the above embodiments, in order to facilitate the placement of battery packs 2 with different layers, one or both side frames of the frame 101 can be opened, so as to facilitate the placement and bonding of battery packs 2 with different layers to the base plate 102 or the partition plate 3.

[0061] The battery pack of the present invention improves heat exchange efficiency, and the heat exchange uniformity of different layers of battery pack 2 and the heat exchange uniformity of battery cells 201 in the same layer is better, reducing the phenomenon of lithium plating in battery cells 201 and extending the service life of battery cells 201.

[0062] The present invention also provides an electrical device including the aforementioned battery pack. Examples of electrical devices include mobile phones, portable devices, laptops, electric vehicles, electric cars, ships, spacecraft, electric toys, and power tools, etc. Spacecraft include, for example, airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include, for example, stationary or mobile electric toys, specifically, game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include, for example, metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, specifically, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0063] In one specific embodiment, the electrical device is an electric vehicle, which includes a chassis, and the battery pack is mounted on the chassis. The battery pack on the electric vehicle has a relatively long battery assembly with a large aspect ratio, resulting in weak structural strength. The multi-layered battery assembly further reduces the strength of the battery assembly. The chassis of the vehicle protects the battery pack, thereby improving its structural strength. The aspect ratio of the battery pack ranges from 1.5 to 5, specifically any value from 1.5, 1.8, 2, 2.5, 3, 3.6, 4.2, 4.5, or 5, or a value between any two values. Setting the aspect ratio within this range allows for full utilization of the longitudinal and transverse beams of the commercial vehicle chassis to provide continuous longitudinal support and lateral constraint for the battery pack, compensating for insufficient bending and torsional stiffness caused by an excessively large aspect ratio. Simultaneously, it considers frame span limitations and overall vehicle energy density requirements, meeting the structural safety and lightweight requirements of the battery pack.

[0064] In the above embodiments, the test method for parameter H1 is as follows: Select battery pack 2 near the bottom plate 102 layer, select battery cells 201 located at the four corners of the housing 1, measure the distance between the terminal post 2011 of the battery cell 201 near the bottom plate 102 and the bottom plate 102, and take the average value, which is recorded as H1mm. The test method for parameter K is as follows: Select battery pack 2 near the bottom plate 102 layer, select battery cells 201 located at the four corners of the housing 1, measure the length and width of the contact surface between the four battery cells 201 and the cold plate with the heat exchange channel, calculate the average area of ​​the contact surface of the four battery cells 201, and record it as S1mm. 2 The average total surface area of ​​the four battery cells 201 was calculated and denoted as S2mm. 2 K = S1 / S2. The range of K is controlled by adjusting the size of the contact surface between the cold plate and the battery cell 201.

[0065] The preparation of the battery cell 201 includes the preparation of the positive electrode, the negative electrode, the electrolyte, and the separator.

[0066] The preparation of the positive electrode sheet is as follows: the prepared positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF) are mixed, and NMP solvent 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 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. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1).

[0067] The preparation of the negative electrode sheet is as follows: 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 onto both surfaces of the negative electrode current collector foil, dried at room temperature, and then transferred to an oven for further drying. Finally, the negative electrode sheet is obtained by rolling and slitting. Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96):(4~2):(2~1):(4~1).

[0068] The electrolyte is prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0069] The diaphragm is prepared by selecting polyethylene film as the diaphragm.

[0070] In the preparation of a single battery cell, the positive electrode sheet, separator, and negative electrode sheet are stacked in sequence and formed into a bare cell by winding or stacking. The bare cell is placed in the battery casing and covered with a cover plate, which is a square shell. A first protrusion is formed around the through hole of the cover plate body through a stamping process, and then an explosion-proof sheet is fixed to the first protrusion to cover the through hole. The battery is dried, injected with electrolyte, and then packaged, allowed to stand, formed, and volume-adjusted to obtain a lithium-ion battery.

[0071] In the selection of materials for the battery, this application may also select other materials, not limited to the materials 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 negative electrode active material may be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0072] The conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene, and carbon nanofibers.

[0073] The adhesive includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0074] The solvent can be deionized water, NMP (N-methylpyrrolidone), alcohol, ether, ketone or other types of pyrrolidone, etc.

[0075] The positive electrode current collector foil can be a metal foil or a composite current collector. For example, as a metal foil, it can be made of stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0076] The negative electrode current collector foil can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium, and can be surface-plated with silver. Composite current collectors may include a polymer base layer and a metal layer. Composite current collectors can be formed by forming metal materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer base material (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0077] In this test, the positive electrode active material of the battery was selected as a nickel-cobalt-manganese ternary LiNi0.6Co0.2Mn0.2O2. The mass ratio of positive electrode active material: conductive agent: binder met 96:2:2. The negative electrode active material was selected as artificial graphite. The ratio of negative electrode active material: conductive agent: thickener: binder met 95:2:1:2.

[0078] Test 1: External short circuit test of battery

[0079] For each embodiment and comparative example, 100 battery packs were prepared as samples. The lithium-ion battery packs were charged at a constant current rate of 1C to the upper limit voltage at room temperature (20°C), and then charged at a constant voltage until the current dropped to 0.05C. After resting for 30 minutes, they were discharged at a 1C rate to the lower limit voltage and then rested for 30 minutes. This constitutes one charge-discharge cycle. Taking this experiment as an example, the ternary lithium battery used had an upper limit voltage of 4.25V and a lower limit voltage of 2.5V.

[0080] For different battery systems, the upper and lower voltage limits need to be adjusted accordingly: Lithium iron phosphate (LFP) system - upper voltage 3.65V, lower voltage 2.5V; ternary lithium (NCM) system - upper voltage 4.25V, lower voltage 2.5V; lithium manganese iron phosphate (LFMP) system - upper voltage 4.25V, lower voltage 2.5V; lithium nickel manganese oxide system - upper voltage 4.8V, lower voltage 3.5V.

[0081] After performing 100 charge-discharge cycles on the lithium-ion battery pack, the lithium-ion batteries were charged at a constant current rate of 1C to the upper limit voltage, and then charged at a constant voltage until the current dropped to 0.05C. After stabilizing for 2 hours, the voltage between the positive and negative terminals of the lithium-ion battery cells at the four corners near the base plate and the two lithium-ion battery cells at the center point of the battery pack was measured using a multimeter (DC voltage range). Figure 19 As shown, the battery cells marked 201A are the four corner cells 201, and the two battery cells marked 201B are the two cells 201 located at the center point. If the voltage of any one of the six battery cells suddenly drops to 0V or close to 0V, the battery pack is considered to be short-circuited.

[0082] If more than 2 out of 100 battery pack samples are short-circuited, the sample is considered unqualified; otherwise, it is considered qualified.

[0083] Test 2: Temperature rise during battery terminal charging and discharging

[0084] For each embodiment and comparative example, 100 battery packs were prepared as samples. At room temperature (20°C), the battery terminals of four lithium-ion battery cells near the four corners and two lithium-ion battery cells at the center of the bottom layer of the battery pack were connected to temperature sensors. The battery pack was then charged at a constant current rate of 4C until the voltage of the battery cells reached the upper limit. Subsequently, constant voltage charging was switched until the current of the battery cells dropped to 0.05C. The temperature changes of the terminals were recorded throughout the charging process. The highest terminal temperatures collected from six battery cells during the charging process were recorded as T1, T2, T3, T4, T5, and T6, respectively. The average value of these values ​​was taken as the highest terminal temperature T of the battery pack.

[0085] If the highest temperature T of the electrode is less than or equal to 65℃, the test result is considered qualified; if the highest temperature T of the electrode is greater than 65℃, it is considered unqualified.

[0086] If more than two out of 100 battery pack samples fail, the sample is considered unqualified; otherwise, it is considered qualified.

[0087] Different systems require corresponding adjustments to the upper and lower voltage limits: Lithium iron phosphate (LFP) - upper limit voltage 3.65V, lower limit voltage 2.5V; Nickel cobalt manganese ternary NCM - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium manganese iron phosphate (LFMP) - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium nickel manganese oxide - upper limit voltage 4.8V, lower limit voltage 3.5V.

[0088]

[0089] Table 1

[0090] The battery packs described above were used in the experiments, and the data obtained are shown in Table 1, Examples 1 to 16. Table 1 shows that in Examples 1 to 11, the samples had H1 / K values ​​of 81.25~700, H1 values ​​of 12~50 mm, and K values ​​of 0.07~0.15. The external short-circuit test results and the temperature rise results during battery terminal charging and discharging all met the design requirements. In Examples 12 to 16, although some parameters (H1 or K) exceeded the above-mentioned ranges, their H1 / K ratios remained within 81.25~700, and the deviations of parameters H1 or K were small. Tests showed that the external short-circuit test results and the temperature rise results during battery terminal charging and discharging in these examples also met the design requirements. These results indicate that, provided H1 / K is within the range of 81.25~700, the set ranges of H1 and K have a certain engineering margin, and the system can still operate normally even with slight deviations.

[0091] In Comparative Examples 1 through 5, the H1 / K values ​​of the samples were not within the specified range, and at least one parameter (H1 or K) exceeded the set range. Specifically, in Comparative Example 1 (H1 / K = 1160), Comparative Example 2 (H1 / K = 68), and Comparative Example 4 (H1 / K = 727.78), the H1 / K values ​​deviated from the upper or lower limit, and the K or H1 values ​​exceeded the set range. Therefore, the temperature rise results of the battery pack's battery terminals during charging and discharging did not meet the design requirements, but the external short-circuit test results met the set requirements. In Comparative Examples 3 and 5, the H1 / K values ​​were less than 81.25 or close to the lower limit, and the H1 value exceeded the set range. Therefore, the external short-circuit test results of the battery pack did not meet the design requirements, but the temperature rise results of the battery terminals during charging and discharging met the design requirements.

[0092] The results above show that H1 / K within the range of 81.25~700 is a fundamental condition for ensuring the battery pack's temperature rise and short-circuit safety, and this constraint plays a decisive role. The independent ranges of H1 and K represent the preferred intervals. Within these intervals, the system has sufficient safety margins. Even if individual parameters slightly exceed these limits, as long as H1 / K remains within the range, both test results for the battery pack will meet the design requirements. Therefore, limiting the value of H1 / K to the range of 81.25-700, while simultaneously limiting the value ranges of the two parameters H1 and K, constitutes a stable design window that balances performance and safety. This ensures that the temperature rise results of the battery terminals during charging and discharging, as well as the external short-circuit test results, both meet the design requirements.

[0093] In the description of this solution, it should be understood that 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. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this solution, "multiple" means two or more, unless otherwise explicitly specified.

[0094] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0095] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A battery pack, characterized in that, The enclosure includes a housing (1) and at least two battery packs (2) disposed within the housing (1). The at least two battery packs (2) are arranged in layers along a first direction. Along the first direction, a partition (3) is provided between adjacent battery packs (2). A baffle is provided on the side of each battery pack (2) away from the partition (3). The housing (1) includes a frame (101), a bottom plate (102), and a top plate (103). The first direction is perpendicular to the large surface direction of the bottom plate (102). The battery packs (2) are placed in the accommodating cavity enclosed by the frame (101), the bottom plate (102), and the top plate (103). The baffle includes the bottom plate (102) and the top plate (103). The battery packs (2) include multiple battery cells (201). The battery packs (2) correspond to multiple battery cells (201). 01) The battery packs are arranged on the same layer along a second direction, which is the length direction of the partition plate (3) and is perpendicular to the large surface of the battery cell (201); the battery cell (201) includes a shell and a terminal post (2011) disposed on the shell, the terminal post (2011) is disposed on the first side (2012) of the shell, and the first side (2012) is perpendicular to the bottom plate (102); the housing (1) also includes a first side plate (104), the first side plate (104) is perpendicular to the bottom plate (102), and the first side plate (104) is parallel to the first side (2012); along the direction perpendicular to the large surface of the first side plate (104), the orthographic projection of the multi-layer battery pack (2) is at least partially coincident with the large surface of the first side plate (104); The partition plate (3), bottom plate (102), top plate (103) and first side plate (104) are respectively provided with heat exchange channels for accommodating heat exchange medium. The battery cell (201) is heat exchanged with the baffle, partition plate (3) and first side plate (104) which are arranged nearby.

2. The battery pack according to claim 1, characterized in that, The first side plate (104) is disposed at one end of the partition plate (3) along a third direction, which is perpendicular to the first direction and the second direction.

3. The battery pack according to claim 2, characterized in that, The battery cell (201) includes a second side (2013), which is disposed opposite to the first side (2012). The first side plate (104) is disposed close to the second side (2013), and the second side (2013) is heat-exchange connected to the first side plate (104).

4. The battery pack according to claim 1, characterized in that, The first side plate (104) is provided with a first flow channel (1041) for accommodating heat exchange medium. Multiple first flow channels (1041) are provided, and different first flow channels (1041) are spaced apart along a first direction. The first flow channels (1041) extend along a second direction.

5. The battery pack according to claim 4, characterized in that, The first flow channel (1041) includes a plurality of first liquid inlet channels (10411), the first liquid inlet channels (10411) are used to communicate with the liquid inlet (1043) of the first side plate (104), and at least two of the battery packs (2) are respectively arranged opposite to at least one of the first liquid inlet channels (10411).

6. The battery pack according to claim 5, characterized in that, The number of first liquid inlet channels (10411) corresponding to each layer of the battery pack (2) is the same.

7. The battery pack according to claim 5, characterized in that, The first flow channel (1041) also includes a plurality of first return flow channels (10412), which are used to communicate with the liquid outlet (1044) of the first side plate (104). The number of first return flow channels (10412) corresponding to each layer of the battery pack (2) is the same, and the first return flow channels (10412) are connected to the first liquid inlet flow channel (10411).

8. The battery pack according to claim 4, characterized in that, The first side plate (104) is provided with an inlet (1043) and an outlet (1044), which are located at the same end of the first side plate (104) along the second direction.

9. The battery pack according to claim 8, characterized in that, Along the first direction, the height of the box (1) ranges from 80 to 500 mm.

10. The battery pack according to claim 4, characterized in that, The first side plate (104) is provided with an inlet (1043) and an outlet (1044). The inlet (1043) and the outlet (1044) are located at both ends of the first side plate (104) along the second direction. Along the second direction, the length of the box (1) ranges from 200 to 1500 mm.

11. The battery pack according to claim 4, characterized in that, The battery cell (201) includes a second side (2013), which is disposed opposite to the first side (2012), and the second side (2013) is heat-exchange connected to at least two of the first flow channels (1041).

12. The battery pack according to claim 4, characterized in that, A partition rib (1042) is provided between adjacent first flow channels (1041), and at least a portion of the partition rib (1042) forms an acute angle α with the surface of the first side plate (104) near the battery cell (201).

13. The battery pack according to any one of claims 1-12, characterized in that, Along the direction perpendicular to the large surface of the first side plate (104), the orthographic projection of the plurality of battery packs (2) is located within the large surface of the first side plate (104).

14. The battery pack according to any one of claims 1-12, characterized in that, The battery pack (2) near the base plate (102) is fixedly connected to the base plate (102). The battery cell (201) includes a second side (2013) opposite to the first side (2012). The first side plate (104) is heat-exchange connected to the second side (2013). Along the first direction, the distance between the pole post (2011) near the base plate (102) and the base plate (102) is H1mm. The ratio of the total area of ​​the heat exchange surface of a single battery cell (201) to the total area of ​​the shell is K. The range of H1 / K is 81.25~700.

15. The battery pack according to claim 14, characterized in that, The range of H1mm is 12~50mm. And / or, K ranges from 0.07 to 0.

15.

16. The battery pack according to claim 14, characterized in that, It also includes a conductive bus (4), which electrically connects at least two adjacent battery cells (201) to their terminals (2011). Along a first direction, the distance between the bottom end of the conductive bus (4) and the base plate (102) is greater than or equal to the distance between the terminal (2011) near the base plate (102) and the base plate (102).

17. The battery pack according to claim 14, characterized in that, It also includes a conductive bus (4), which electrically connects at least two adjacent battery cells (201) to their terminals (2011). Along the first direction, the distance between the bottom end of the conductive bus (4) and the base plate (102) is less than the distance between the terminal (2011) near the base plate (102) and the base plate (102), and H1mm ranges from 22 to 50mm.

18. The battery pack according to claim 17, characterized in that, The distance between the conductive bus (4) and the base plate (102) is in the range of 3~20mm.

19. The battery pack according to any one of claims 16-18, characterized in that, The conductive bus (4) is covered with an insulating layer at one end near the base plate (102).

20. The battery pack according to claim 14, characterized in that, The electrode (2011) includes a positive electrode and a negative electrode, both of which are disposed on the first side (2012). The positive electrode and the negative electrode are spaced apart along the first direction, and the range of K is 0.07~0.

13.

21. The battery pack according to claim 1, characterized in that, The electrode post (2011) includes a positive electrode post and a negative electrode post, one of which is disposed on the first side surface (2012), and the other is disposed on the second side surface (2013) opposite to the first side surface (2012); The first side (2012) and the second side (2013) are respectively disposed at both ends of the battery cell (201) along a third direction; There are two first side plates (104), and the two first side plates (104) are respectively disposed at both ends of the partition plate (3) along the third direction. One first side plate (104) is heat-exchange connected to the first side (2012), and the other first side plate (104) is heat-exchange connected to the second side (2013).

22. The battery pack according to any one of claims 1-12, characterized in that, The surface of the shell used for heat exchange connection with the partition plate (3) or baffle is the first end face, and the area of ​​the first end face is greater than the area of ​​the first side face (2012).

23. The battery pack according to claim 22, characterized in that, The length direction of the first end face is perpendicular to the length direction of the partition plate (3).

24. The battery pack according to claim 1, characterized in that, At least two partition plates (3) are provided, and the flow channels in the different partition plates (3) have the same cross-sectional area.

25. The battery pack according to claim 1, characterized in that, The partition plate (3) is provided with a second flow channel (301) for accommodating heat exchange medium, and the second flow channel (301) extends along a second direction.

26. The battery pack according to claim 1, characterized in that, The base plate (102) is provided with a third flow channel (1021) for accommodating heat exchange medium, and the third flow channel (1021) extends along the second direction; The thickness of the base plate (102) is greater than the thickness of the partition plate (3).

27. The battery pack according to claim 26, characterized in that, The cross-sectional area of ​​the flow channel in the partition plate (3) is greater than the cross-sectional area of ​​the flow channel in the bottom plate (102).

28. The battery pack according to claim 1, characterized in that, The base plate (102) is bonded to the battery pack (2) through a first adhesive layer, the partition plate (3) is connected to the battery pack (2) through a second adhesive layer, and the top plate (103) is bonded to the battery pack (2) through a third adhesive layer.

29. The battery pack according to claim 28, characterized in that, The thickness of the first adhesive layer is greater than the thickness of the second adhesive layer; and / or, the thickness of the third adhesive layer is greater than the thickness of the second adhesive layer.

30. The battery pack according to claim 28, characterized in that, The thickness of the first adhesive layer, the second adhesive layer, or the third adhesive layer ranges from 0.5 to 3 mm.

31. The battery pack according to claim 1, characterized in that, The battery pack (2) has three layers along the first direction. The orthographic projection of the three layers of the battery pack (2) along the direction perpendicular to the large surface of the first side plate (104) is located within the large surface area of ​​the first side plate (104).

32. The battery pack according to claim 31, characterized in that, The length of the box (1) along the second direction is 200~1500mm.

33. An electrical device, characterized in that, Includes the battery pack as described in any one of claims 1-32.

34. The electrical appliance according to claim 33, characterized in that, The electrical device is an electric vehicle, which includes a chassis and the battery pack is mounted on the chassis.

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