Power battery lower shell and power battery pack

Abstract

This utility model discloses a lower housing and a power battery pack. The lower housing includes a liquid cooling plate, a flame-retardant and heat-insulating layer, and a continuous fiber composite material layer. The liquid cooling plate has cooling channels at its bottom and is stamped into a square, integrated basin-shaped structure to accommodate the power battery. The flame-retardant and heat-insulating layer is integrally formed with the continuous fiber composite material layer by hot pressing and wraps around the bottom and peripheral walls of the liquid cooling plate from the inside out. This utility model features a compact structure, high structural strength, and strong heat insulation and flame-retardant capabilities, significantly improving the operational safety of the power battery.

Description

Technical Field

[0001] This utility model relates to the field of power battery technology, specifically to a lower housing of a power battery and a power battery pack. Background Technology

[0002] When thermal runaway occurs in a new energy vehicle battery, heat and gas are rapidly released from the battery, posing a significant fire hazard. Thermal runaway in a power battery can be caused by manufacturing defects, heat accumulation, internal short circuits, or external impacts or trauma. Furthermore, the thermal runaway of a single battery can trigger the thermal runaway of adjacent batteries, leading to a dangerous chain reaction. This is the most significant safety hazard facing new energy vehicles.

[0003] Current technology typically involves enclosing the battery within a refractory barrier wall. However, the thermal runaway temperature of ternary lithium batteries is as high as 1300℃, and the barrier wall usually cannot provide sufficient time to prevent thermal runaway from spreading to other nearby batteries. Furthermore, it is difficult to prevent explosions using pressure relief valves. While some existing power battery products cover the top surface of the battery pack with materials such as mica and aerogel after the battery pack modules are assembled, this does not completely enclose the entire battery casing and still cannot prevent or delay thermal runaway.

[0004] In existing technologies, the lower casing of battery packs is primarily made of metal, making it difficult to composite with inorganic flame-retardant and heat-resistant materials. Existing technology KR1020230044044A discloses a method for manufacturing the lower casing of a battery pack, which involves positioning a fiber preform on the outer surface of the casing body and then integrating the casing body and the fiber preform using a curing composition. While this achieves composite molding of the metal casing body and the fiber preform, the following drawbacks still exist: (1) The shell body is made of aluminum material with excellent rigidity, impact resistance, flame retardancy and light weight. However, the melting point of aluminum material is only about 500°C. When the power battery thermally runs away, it cannot effectively delay the fire and explosion of the power battery. Moreover, the shell body is only a single-layer metal structure with low heat dissipation capacity.

[0005] (2) The fiber preform is made of sheet fiber woven material or prepreg through electric field origami process to form a shape corresponding to the shell body. There are connection gaps between the various surfaces of the fiber preform. The vibration generated during the long-term service of the power battery pack can easily cause water leakage in the connection gaps, resulting in a significant safety hazard.

[0006] (3) The shell body and the fiber preform are prone to separation due to the large difference in materials, resulting in unstable overall structural strength of the lower shell of the battery.

[0007] (4) During the injection molding process, the curing composition typically takes 5 to 10 minutes to flow and distribute within the mold, and trimming is required in the later stages of molding, which increases the number of steps and reduces production efficiency. Furthermore, reactive curing compositions cannot be repeatedly recycled, increasing production costs.

[0008] (5) The heat preservation capacity of fiber preforms is low. When the power battery pack is used in cold winter or high-altitude mountainous areas, if the inside of the battery shell cannot be kept within a certain temperature range, the effective capacity of the power battery will be severely reduced, resulting in a sharp decline in the range of new energy vehicles. Utility Model Content

[0009] The technical problem to be solved by this utility model is to overcome the shortcomings of existing power battery lower casing structures, such as low structural strength, poor heat insulation and flame retardancy, and complicated production processes, and to provide a power battery lower casing and power battery pack with a compact structure, high structural strength, and strong heat insulation and flame retardancy.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A power battery lower casing includes a liquid cooling plate, a flame-retardant and heat-insulating layer, and a continuous fiber composite material layer; the bottom of the liquid cooling plate is provided with a cooling channel, and the liquid cooling plate is stamped into a square integrated basin structure to accommodate the power battery; the flame-retardant and heat-insulating layer and the continuous fiber composite material layer are integrally formed by hot pressing and wrapping around the bottom wall and the perimeter wall of the liquid cooling plate from the inside to the outside. As a further improvement of this utility model, the liquid cooling plate includes an upper plate and a lower plate, the bottom of the lower plate is stamped with a flow channel, and the upper plate is welded to the lower plate, forming a cooling channel with the flow channel. As a further improvement of this utility model, the four sides of the lower plate are all stamped and extended into side walls. As a further improvement of this utility model, it also includes a thermoplastic molding body, which is wrapped around the outer periphery of the continuous fiber composite material layer and the edge of the liquid cooling plate. As a further improvement of this utility model, the inner side of the liquid cooling plate is provided with multiple partition walls, and the thermoplastic molded body is wrapped around the outer periphery of the partition walls. As a further improvement of this utility model, both the upper plate and the lower plate are made of aluminum alloy. As a further improvement of this utility model, the thickness of the lower plate is 0.5mm to 1.5mm. As a further improvement of this utility model, the thickness of the flame-retardant and heat-insulating layer is 0.2 mm to 2 mm; the thickness of the continuous fiber composite material layer is 1 mm to 5 mm. As a further improvement of this utility model, the flame-retardant and heat-insulating layer contains mica; the continuous fiber composite material layer contains one or more of nitrogen-based intumescent flame retardants, phosphorus-based carbon-forming flame retardants, and silicon-based anti-drip flame retardants.

[0011] As a general technical concept, this utility model also provides a power battery pack, including the aforementioned lower housing of the power battery. Compared with the prior art, the advantages of this utility model are: 1. The lower casing of the power battery of this utility model is formed by stamping a liquid cooling plate into a square, integrated basin-shaped structure to house the power battery. A flame-retardant and heat-insulating layer and a continuous fiber composite material layer are hot-pressed together and then wrapped from the inside out around the bottom and perimeter walls of the liquid cooling plate, thus forming a weld-free lower casing. Because it does not contain low-strength welds, the lower casing has higher overall rigidity, better resisting structural bending and torsion, and is more than 30% lighter than traditional metal casings. Furthermore, the composite material lower casing has higher damping, absorbing more energy to resist impacts and stone chip impacts. The composite material lower casing can also effectively attenuate noise and vibration and provide ideal thermal insulation and electrical insulation properties. More importantly, by comprehensively laying flame-retardant and heat-insulating materials around the perimeter and bottom plate of the battery lower casing, it can effectively delay ignition in the event of thermal runaway, significantly reducing casualties caused by thermal runaway in new energy vehicles. 2. The lower casing of the power battery of this utility model contains mica in the flame-retardant and heat-insulating layer and flame retardant in the continuous fiber composite material layer. It can not only play a flame-retardant role, but also have a heat-insulating role. In the case of thermal runaway, it can effectively delay the ignition. In cold environments such as winter or high-altitude mountainous areas, it can also keep the inside of the lower casing of the battery within a certain temperature range, prevent the battery heat from dissipating too quickly and causing a serious drop in the effective capacity of the battery, and ensure that new energy vehicles still have good range in cold environments.

[0012] 3. The power battery pack of this utility model includes the aforementioned lower housing of the power battery, and therefore also has the aforementioned advantages. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the cross-sectional structure of the lower housing of the power battery composite material in a specific embodiment of this utility model; Figure 2 This is a schematic diagram of the three-dimensional structure of the lower housing of the power battery composite material in a specific embodiment of this utility model; Figure 3 This is a schematic diagram of the structural principle of the upper plate in a specific embodiment of this utility model; Figure 4 This is a schematic diagram of the structural principle of the lower plate in a specific embodiment of this utility model; Figure 5 This is a schematic diagram of the structural principle of the lower plate after the side wall is stamped out in a specific embodiment of this utility model; Figure 6 This is a schematic diagram illustrating the structural principle of the flame-retardant and heat-insulating layer and the continuous fiber composite material layer in a specific embodiment of this utility model; Legend: 1. Top plate; 2. Bottom plate; 21. Flow channel; 22. Side wall; 3. Flame-retardant and heat-insulating layer; 4. Continuous fiber composite material layer; 5. Thermoplastic molded body; 6. Pre-formed hole; 7. Partition wall; 8. Reinforcing rib. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0015] In the description of this utility model, it should be understood that the terms "side", "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0016] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "multiple" means two or more, unless otherwise explicitly specified.

[0017] Example like Figure 1 and Figure 2 As shown, the lower casing of the power battery of this utility model includes a liquid cooling plate, a flame-retardant and heat-insulating layer 3, and a continuous fiber composite material layer 4. The bottom of the liquid cooling plate is provided with a cooling channel, and the liquid cooling plate is stamped into a square, integrated basin-shaped structure to accommodate the power battery. The flame-retardant and heat-insulating layer 3 and the continuous fiber composite material layer 4 are integrally formed by hot pressing and wrap around the bottom and peripheral walls of the liquid cooling plate from the inside out. In this embodiment, a square, integrated basin-shaped structure is formed by stamping a liquid cooling plate to house the power battery. The flame-retardant and heat-insulating layer 3 and the continuous fiber composite material layer 4 are then hot-pressed together and wrapped around the bottom and perimeter walls of the liquid cooling plate from the inside out, forming a weld-free lower casing for the power battery. Because it lacks low-strength welds, the lower casing has higher overall rigidity, better resisting structural bending and torsion, and is more than 30% lighter than traditional metal casings. Furthermore, the composite material lower casing has higher damping, absorbing more energy to resist impacts and stone chips. It also effectively attenuates noise and vibration and provides ideal thermal insulation and electrical insulation properties. More importantly, by comprehensively layering flame-retardant and heat-insulating materials around the battery lower casing and on the bottom plate, ignition can be effectively delayed in the event of thermal runaway, significantly reducing casualties caused by thermal runaway in new energy vehicles.

[0018] like Figure 1 , Figure 3 and Figure 4 As shown, the liquid cooling plate includes an upper plate 1 and a lower plate 2. A flow channel 21 is stamped on the bottom of the lower plate 2. The upper plate 1 is welded to the lower plate 2, and together with the flow channel 21, they form a cooling channel. The two flow channels 21 are arranged in a zigzag pattern at the bottom of the lower plate 2 to increase the heat exchange area and improve the heat dissipation effect.

[0019] like Figure 5 As shown, the four sides of the lower plate 2 are stamped and extended into side walls 22. The lower plate 2 is stamped to form a square, one-piece basin-shaped structure, which has high structural strength and avoids sealing defects.

[0020] like Figure 1 As shown, it also includes a thermoplastic molded body 5, which wraps around the outer periphery of the continuous fiber composite layer 4 and the upper edge of the lower plate 2.

[0021] In the manufacturing process of the lower casing of the power battery in this embodiment, the upper plate 1 and the lower plate 2 can be welded together to form a liquid cooling plate, i.e., preform A; then, the flame-retardant heat insulation layer 3 and the continuous fiber composite material layer 4 are hot-pressed together to form preform B; next, preform A is stacked inside preform B, and holes are formed to create preformed holes 6; finally, the preforms A and B after forming holes are heated to 200°C to 330°C, placed in a mold, and molded or injection-molded using molten discontinuous fiber reinforced composite material to achieve the integral molding of preforms A and B, and to complete the covering, reinforcement, and separation, resulting in the desired product. Figure 2 The image shows a one-piece molded power battery composite material lower casing. The discontinuous fiber composite material, in its molten state, forms a thermoplastic molded body 5 with preforms A and B under molding or injection molding conditions.

[0022] As can be seen, the discontinuous fiber composite material mainly covers preforms A and B, while also preparing reinforcing ribs 8 to enhance the structural strength of the lower battery casing. More importantly, it is molded to connect to the vehicle body's outer cladding. The bolt hole positions of the outer cladding can be flexibly designed according to the specific vehicle model, or flange edge holes can be designed on the peripheral wall of the lower casing to facilitate bolt connection with the battery pack cover.

[0023] In other embodiments, the preform A, flame-retardant and heat-insulating layer 3, and continuous fiber composite material layer 4 can be hot-stamped together first, and then hot-melted with discontinuous fiber composite material to form an integral lower shell of the power battery composite material. The composite material lower shell is easy to integrally mold into an ideal shape, with fast production cycle and low cost. Moreover, the shell layers will not separate, and the strength is high, especially after injection molding.

[0024] like Figure 1 As shown, the inner side of the liquid cooling plate is provided with multiple partition walls 7, thereby defining multiple units. The thermoplastic molded body 5 is wrapped around the outer periphery of the partition walls 7. The partition walls 7 have a draft angle greater than 3° to 10°, and the holes in the preforms A and B form bolt-like reinforcing ribs 8. If it is necessary to connect the partition walls 7 to the battery cover, connection bolt holes can be provided in the partition walls 7.

[0025] In other embodiments, a layer of thermoplastic molding compound 5 may be attached to the entire bottom plate of the liquid cooling plate to increase the thickness of the bottom wall of the battery lower casing, thereby providing higher strength and rigidity to resist the weight of the battery.

[0026] In this embodiment, both the upper plate 1 and the lower plate 2 are made of aluminum alloy. The upper plate 1 is preferably made of 3003, 5053, or 6061 aluminum alloy. The lower plate 2 is preferably made of 3003 or 6061 aluminum alloy, and the flow channel 21 is formed by stamping through a designed flow channel, such as... Figure 4 As shown. The thickness of the lower plate 2 is 0.5 mm to 1.5 mm, preferably 0.8 mm to 1.0 mm.

[0027] In this embodiment, the thickness of the flame-retardant and heat-insulating layer 3 is 0.2 mm to 2 mm, preferably 0.4 mm, 0.6 mm, or 0.8 mm. The thickness of the continuous fiber composite material layer 4 is 1 mm to 5 mm, preferably 3 mm.

[0028] In this embodiment, the flame-retardant and heat-insulating layer 3 is a mica board formed by combining mica with aerogel felt, flame-retardant foam, or ceramicized silicone rubber. Preferably, the flame-retardant and heat-insulating layer 3 is formed by bonding mica with silicone rubber, heating, and pressing it into a mica board form. The flame-retardant and heat-insulating layer 3 not only provides flame retardancy but also insulation, effectively delaying ignition in the event of thermal runaway. This significantly reduces casualties caused by thermal runaway in new energy vehicles. In cold environments such as winter or high-altitude mountainous areas, it also helps maintain the internal temperature of the battery pack within a certain range, preventing excessive heat dissipation and a severe decrease in battery capacity, ensuring that new energy vehicles still have good range in cold environments.

[0029] In this embodiment, the continuous fiber composite layer 4 contains thermoplastic resin and fiber components. The thermoplastic resin and fiber components can be selected from conventional materials used in the art, and will not be elaborated further here. The resin component in the discontinuous fiber composite material is the same as that in the continuous fiber composite layer 4, and the integrally molded composite layer has better mechanical strength.

[0030] In addition, the continuous fiber composite layer 4 also contains one or more of the following: nitrogen-based intumescent flame retardants, phosphorus-based char-forming flame retardants, and silicon-based anti-drip flame retardants. The flame retardant content is 10 wt% to 30 wt%, and the flame retardant rating is UL-94 V0. Under high-temperature conditions, the resin in the continuous fiber composite layer 4 rapidly chars, and combined with the mesh fibers, it achieves better heat transfer barrier.

[0031] In this embodiment, the composite molding method for the flame-retardant heat insulation layer 3 and the continuous fiber composite material layer 4 is as follows: A 0.4mm thick mica plate and a 3mm thick polyamide 6 are selected as the matrix. Both are heated to 200℃~330℃ in an infrared heating furnace and then hot-pressed to obtain the desired composite material. Figure 6 Preform B is shown.

[0032] Both the flame-retardant heat insulation layer 3 and the continuous fiber composite material layer 4 have flame-retardant functions. Under external fire and high heat conditions, they char and retard, preventing heat sources from entering the battery pack. This significantly improves the flame-retardant performance of the lower shell of the power battery composite material, solves the problem of explosion caused by external flames, delays fire and explosion, increases escape time, and greatly reduces casualties caused by thermal runaway of new energy vehicles.

[0033] In this embodiment, a power battery pack is also provided, including the aforementioned lower housing of the power battery. The power battery pack offers improved safety and can effectively address thermal runaway.

[0034] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. A lower casing for a power battery, characterized in that, It includes a liquid cooling plate, a flame-retardant heat insulation layer (3) and a continuous fiber composite material layer (4); the bottom of the liquid cooling plate is provided with a cooling channel, and the liquid cooling plate is stamped into a square integrated basin structure to accommodate the power battery; the flame-retardant heat insulation layer (3) and the continuous fiber composite material layer (4) are hot-pressed into one piece and wrapped around the bottom wall and the perimeter wall of the liquid cooling plate from the inside to the outside.

2. The lower housing of the power battery according to claim 1, characterized in that, The liquid cooling plate includes an upper plate (1) and a lower plate (2). The bottom of the lower plate (2) is stamped with a flow channel (21). The upper plate (1) is welded to the lower plate (2) and together with the flow channel (21) form a cooling channel.

3. The lower housing of the power battery according to claim 2, characterized in that, The lower plate (2) is stamped and extended into sidewalls (22) on all four sides.

4. The lower housing of the power battery according to claim 2, characterized in that, It also includes a thermoplastic molding body (5), which is wrapped around the periphery of the continuous fiber composite layer (4) and the edge of the liquid cooling plate.

5. The lower housing of the power battery according to claim 4, characterized in that, The liquid cooling plate has multiple partition walls (7) on its inner side, and the thermoplastic molded body (5) is wrapped around the outer periphery of the partition walls (7).

6. The lower housing of the power battery according to any one of claims 2 to 5, characterized in that, Both the upper plate (1) and the lower plate (2) are made of aluminum alloy.

7. The lower housing of the power battery according to any one of claims 2 to 5, characterized in that, The thickness of the lower plate (2) is 0.5mm to 1.5mm.

8. The lower housing of the power battery according to any one of claims 1 to 5, characterized in that, The thickness of the flame-retardant and heat-insulating layer (3) is 0.2 mm to 2 mm; the thickness of the continuous fiber composite material layer (4) is 1 mm to 5 mm.

9. The lower housing of the power battery according to any one of claims 1 to 5, characterized in that, The flame-retardant and heat-insulating layer (3) is a mica board formed by combining mica with aerogel felt, flame-retardant foam or ceramicized silicone rubber; the continuous fiber composite material layer (4) contains one or more of nitrogen-based intumescent flame retardants, phosphorus-based carbon-forming flame retardants and silicon-based anti-drip flame retardants.

10. A power battery pack, characterized in that, Includes the lower housing of the power battery as described in any one of claims 1 to 9.

Images