Power battery pack capable of counteracting mechanical shock

Abstract

The invention relates to a power battery technology, and discloses a power battery pack capable of counteracting mechanical shock, comprising: a housing having a sealed structure; the plurality of soft package battery cells are arranged in the shell; and the filling liquid is filled in all residual space in the shell, and the density of the filling liquid is similar to the average density of the plurality of soft package battery cells. According to the invention, the buoyancy can be utilized to counteract mechanical impact, improve the impact resistance of the battery, prolong the service life of the battery, reduce the risk of thermal runaway and improve the fireproof safety performance, and meanwhile, the energy density can be improved and the cost can be reduced.

Description

Technical Field

[0001] This application relates to battery technology, particularly to power battery technology. Background Art

[0002] As a core technical aspect in the application of power battery packs, the main challenge faced during vehicle operation is the continuous impact of high-intensity mechanical shocks. These shocks not only threaten the structural integrity of the battery but may also cause the battery to overheat or experience thermal runaway, thereby triggering serious disasters such as deflagration. Therefore, protecting the battery from mechanical shock damage and reducing the risk of thermal runaway caused thereby have become key requirements in the design of battery packs.

[0003] Current technical solutions have not been able to effectively address these challenges. Although the industry has been continuously improving the structure of battery packs to enhance their shock resistance, there are still many limitations. For example, although complex internal support structures can provide certain protection, they increase the weight and cost of the battery pack and also limit the improvement of energy density. In addition, the effectiveness of traditional solutions in terms of fire safety also needs to be improved. Summary of the Invention

[0004] The purpose of this application is to provide a power battery pack that can counteract mechanical shocks, enabling the battery function to be protected from mechanical shock damage while simplifying the structure, reducing volume, weight, and cost.

[0005] This application discloses a power battery pack that can counteract mechanical shocks, including:

[0006] A housing, the housing being a sealed structure;

[0007] A plurality of soft-pack battery cells placed inside the housing, the gap between the housing and the plurality of soft-pack battery cells being greater than the deformation of the housing under the estimated maximum shock;

[0008] A filling liquid that fills all the remaining space inside the housing, wherein the density of the filling liquid is within the range of ±25% of the average density of the plurality of soft-pack battery cells; and

[0009] Wires between the plurality of soft-pack battery cells, the wires realizing the connection of positive and negative electrodes between adjacent soft-pack battery cells.

[0010] In a preferred example, the density of the filling liquid is substantially the same as the average density of the plurality of soft-pack battery cells.

[0011] In a preferred example, the soft-pack battery cell further includes an exhaust safety valve, one end face of the soft-pack battery cell is fixedly sealed with the housing, and the positive and negative electrodes and the exhaust safety valve of the soft-pack battery cell are led out of the housing from the end face where the soft-pack battery cell is fixedly sealed with the housing.

[0012] In a preferred example, the soft-pack battery cell further includes an exhaust safety valve. The opposite two end faces of the soft-pack battery cell are both fixedly sealed with the outer shell. The lead wire of the first electrode of the soft-pack battery cell and the exhaust safety valve are led out of the outer shell from one end face of the soft-pack battery cell, and the lead wire of the second electrode of the soft-pack battery cell is led out of the outer shell from the other end face of the soft-pack battery cell.

[0013] In a preferred example, the plurality of soft-pack battery cells and their positive and negative electrodes are all surrounded by the filling liquid in the outer shell, and the positive and negative electrodes of the plurality of soft-pack battery cells are all arranged on one end face of the plurality of soft-pack battery cells; and,

[0014] The power battery pack further includes positive and negative bus lead-out terminals on the outer shell. The positive and negative bus lead-out terminals are respectively electrically connected to the positive and negative electrodes of the first and last two soft-pack battery cells among the plurality of soft-pack battery cells, so as to realize the series connection of all the soft-pack battery cells; and,

[0015] Insulation measures are taken for the wires between the plurality of soft-pack battery cells, the positive and negative electrodes of the plurality of soft-pack battery cells, and the contact surfaces between the plurality of soft-pack battery cells and the outer shell to make them insulated.

[0016] In a preferred example, the density of the filling liquid is substantially the same as the average density of the plurality of soft-pack battery cells.

[0017] In a preferred example, the plurality of soft-pack battery cells are arranged with a minimum gap. The positive and negative electrodes of adjacent soft-pack battery cells are connected by wires, wherein the minimum gap means that the gap width is less than 0.5 mm.

[0018] In a preferred example, the outer shell is a rectangular box body, and the plurality of soft-pack battery cells are arranged along the length direction of the outer shell.

[0019] In a preferred example, the gap between the outer shell and the plurality of soft-pack battery cells is between 0.5 mm and 5 mm.

[0020] In a preferred example, the filling liquid contains a substance component with a flame-retardant and fire-extinguishing effect.

[0021] In the embodiment of the present application, the principle of liquid buoyancy is innovatively applied, effectively offsetting the stress generated by mechanical shock, thereby comprehensively eliminating the influence of external shock on the battery. The application of this structure not only significantly extends the service life of the battery, but also greatly reduces the risk of battery thermal runaway caused by mechanical shock, providing stronger protection for battery safety. Specifically, the embodiment of the present application has the following technical effects:

[0022] Battery protection: Greatly reduces the transmission of mechanical shock to the battery, protects the battery from damage, and extends its service life.

[0023] Reduced risk of thermal runaway: Greatly reduces the likelihood of battery thermal runaway and deflagration caused by shock.

[0024] Simplified structure: Since the battery is in a suspended state, the need for internal support structures within the battery pack is reduced, simplifying the battery pack structure.

[0025] Cost and weight advantages: By removing the hard shell and internal support structures of conventional power batteries, the cost and weight are reduced, and the energy density is increased.

[0026] Application of fire extinguishing agent: An innovative idea of using a flame-retardant fire extinguishing agent with a density close to the overall density of the battery as the filling liquid is proposed, further enhancing the safety of the battery pack. The filling liquid can be an insulating substance to avoid short circuits in extreme cases.

[0027] A large number of technical features are described in the specification of this application, distributed in various technical solutions. If all possible combinations of technical features (i.e., technical solutions) of this application are listed, the specification will become overly lengthy. To avoid this problem, each technical feature disclosed in the above-mentioned invention content of this application, each technical feature disclosed in the following embodiments and examples, and each technical feature disclosed in the drawings can be freely combined with each other to form various new technical solutions (these technical solutions are all considered to have been described in this specification), unless the combination of such technical features is technically infeasible. For example, in one example, features A + B + C are disclosed, and in another example, features A + B + D + E are disclosed. Features C and D are equivalent technical means that play the same role, and only one of them can be used technically and it is impossible to use both simultaneously. Feature E can be combined with feature C technically. Then, the solution of A + B + C + D should not be considered to have been described because it is technically infeasible, while the solution of A + B + C + E should be considered to have been described. Description of the Drawings

[0028] Figure 1 is a schematic structural diagram of a power battery pack capable of offsetting mechanical shock according to the first embodiment of the present application;

[0029] Figure 2 is a schematic principle diagram of a power battery pack capable of offsetting mechanical shock according to the first embodiment of the present application;

[0030] Figure 3 is a schematic structural diagram of a power battery pack capable of offsetting mechanical shock according to the second embodiment of the present application;

[0031] Figure 4It is a schematic structural diagram of a power battery pack capable of offsetting mechanical shock according to the third embodiment of the present application;

[0032] Figure 5 and Figure 6 It is a schematic diagram of a single-layer array structure of a power battery pack capable of offsetting mechanical shock according to the present application. Specific Embodiments

[0033] In the following description, many technical details are presented for the reader to better understand the present application. However, those of ordinary skill in the art can understand that even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0034] The following briefly describes some innovative points of the present application:

[0035] Utilization of liquid buoyancy: A unique liquid filling method is adopted, and the battery pack is filled with a filling liquid whose density is approximately equal to the overall density of the soft-pack battery cells. This design enables the soft-pack battery cells to float in the filling liquid, and the buoyancy of the filling liquid is used to offset the inertial force generated by mechanical shock, thereby protecting the soft-pack battery cells from shock damage.

[0036] Simplification of the battery pack structure: Since the soft-pack battery cells float in the filling liquid, the need for internal support structures in the battery pack is reduced, simplifying the overall structure of the battery pack. This simplification not only reduces the weight but also lowers the manufacturing cost.

[0037] Protection and lifespan extension of soft-pack battery cells: The innovative structure completely eliminates the direct damage of mechanical shock to soft-pack battery cells, significantly extends the service life of soft-pack battery cells, and reduces the risk of battery thermal runaway and explosion caused by shock.

[0038] Reduction of the manufacturing difficulty of soft-pack battery cells: Since soft-pack battery cells no longer bear mechanical shock, the requirement for their structural strength is reduced, which is conducive to simplifying the production process and thus reducing costs.

[0039] Dual functions of the fire extinguishing agent: It is proposed to use a flame-retardant fire extinguishing agent with a density close to the overall density of the battery as the filling liquid, enhancing the safety of the battery pack. Because the filling liquid as the fire extinguishing agent always surrounds the soft-pack battery cells, when the soft-pack battery cells are damaged and a fire is likely to occur, this fire extinguishing agent can act immediately to provide additional safety protection.

[0040] Space saving and weight reduction: The strengthening crossbeam and hard shell are removed, smaller soft-pack battery cells are used, and the soft-pack battery cells are closely arranged, effectively reducing the volume and weight of the battery pack and increasing the energy density.

[0041] Overall, through innovative filling liquid filling and structural design, this invention significantly improves the safety, reliability, and economy of the battery pack, while also optimizing its structure and performance.

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the following will further describe the implementation manners of this application in detail with reference to the accompanying drawings.

[0043] The first implementation manner of this application relates to a power battery pack that can counteract mechanical shock. As Figure 1 shown, the outer shell 11 of the battery pack is a completely sealed box structure. Each soft-pack battery cell 13 is evenly arranged within the outer shell 11. Through an opening on the outer shell, one end of the soft-pack battery cell 13 is exposed and sealed and fixed to the outer shell 11. This design ensures the complete sealing inside the battery pack, while exposing the positive and negative electrodes 14 and the exhaust safety valve 16 of the soft-pack battery cell 13 outside the battery pack. The entire interior of the battery pack is filled with a filling liquid 12, which occupies all the remaining space without leaving any voids. The density of the filling liquid 12 is equal to the overall density of the soft-pack battery cells 13, that is, the ratio of the mass of the filling liquid to the volume of the soft-pack battery cells. Therefore, the soft-pack battery cells 13 remain suspended in the filling liquid 12 by buoyancy, and the gravity and buoyancy cancel each other out. According to the principles of physics, all mechanical shocks applied to the outer shell 11 ultimately act on the soft-pack battery cells 13 in the form of acceleration, generating inertial forces. Since this inertial force also acts on the filling liquid 12, the buoyancy force received by the soft-pack battery cells 13 exactly cancels out this force. In this way, as long as the outer shell 11 remains intact, regardless of the mechanical shock suffered, the total force borne by the battery is always zero. Preferably, the filling liquid is an insulating liquid.

[0044] To explain the working principle of this innovative structure, the concept of a non-inertial reference frame in physics needs to be introduced. In this reference frame, the outer shell and its contents are regarded as the same system. Regardless of how the outer shell moves, the internal objects should remain stationary relative to the outer shell. If the internal objects move relative to the outer shell, it may lead to collisions and damage. For example, as Figure 2 shown in the left figure, when the outer shell moves to the right with an acceleration of a, from the perspective of the inside of the system, the internal object M is affected by the acceleration a, generating an effect equivalent to an inertial force Fi.

[0045] Fi = -a * M

[0046] In this case, the object M will accelerate to the left relative to the outer shell. This phenomenon is similar to what people experience on a bus: when the bus accelerates, people feel their bodies tilt backward; when the bus brakes, they feel their bodies tilt forward. In a battery pack, to prevent the soft-pack battery cells from moving relative to the outer shell, it is usually necessary to fix the soft-pack battery cells through structural supports and buffers to prevent damage caused by extrusion or collision during movement. These support and buffer structures can be the structures inside the battery pack or the strengthened hard shells of the soft-pack battery cells themselves.

[0047] However, the innovative structure adopts a different method, as Figure 2 shown in the right figure of . This structure completely fills the internal space of the battery pack with a filling liquid. In this non-inertial reference frame, an object immersed in the filling liquid will be subject to the buoyancy force generated by the filling liquid. This buoyancy force Fb is equal to the product of the acceleration experienced by the reference frame and the mass of the displaced filling liquid:

[0048] Fb = a * M_drain

[0049] When the density of the filling liquid is equal to the density of the object M, the mass of the object M is equal to the mass of the displaced filling liquid M_{drain}, and at this time:

[0050] Fi = -Fb

[0051] This means that the inertial force Fi acting on the object is completely offset by the buoyancy force Fb. Therefore, when the density of the object is equal to the density of the filling liquid, the object will remain suspended in the filling liquid. Regardless of any mechanical shock in any direction or magnitude, the resultant force acting on the object in the reference frame is always zero, thus maintaining relative rest.

[0052] In terms of the battery pack of an electric vehicle, if the innovative structure described in this article is adopted, it means that the battery pack will use a sturdy outer shell similar to the traditional one, and at the same time be equipped with an enhanced sealing design to ensure that the outer shell is a completely closed container. After arranging the internal single soft-pack battery cells, the next step is to inject a filling liquid with a density equal to the overall density of the soft-pack battery cells to fill all the remaining space inside the battery pack. This design ensures that the soft-pack battery cells are suspended in the filling liquid and are not affected by any mechanical shock borne by the outer shell, thus remaining stationary relative to the outer shell and avoiding collision and deformation. In this way, there is no need for any additional anti-shock support structure between the soft-pack battery cells and the outer shell, and the soft-pack battery cells do not need to use a sturdy hard shell, and flexible soft-pack batteries can meet the requirements. In addition, the inside of the soft-pack battery cells will not be subject to any stress from external shocks, which is extremely beneficial for preventing damage to the soft-pack battery cells and extending their service life.

[0053] The following further explains the specific implementation method in this embodiment.

[0054] Clearance between the outer shell and the soft-pack battery cells:

[0055] In this structure, the smaller the volume of the filling liquid filled in the gap, the lighter the weight of the battery pack. However, it should be noted that under mechanical shock, the outer shell may undergo slight elastic deformation. If the gap is too small, the deformed outer shell may come into contact with the soft-pack battery cell and cause damage. Therefore, a reasonable gap needs to be reserved. In the example of installation on an automotive chassis, the gap width between the outer shell and the soft-pack battery cell should be between 0.5 mm and 5 mm. In principle, the gap width between the outer shell and the soft-pack battery cell is preferably greater than the deformation of the outer shell under the estimated maximum shock. This deformation can be calculated based on the estimated maximum shock (such as the maximum acceleration during an emergency vehicle brake, or the maximum acceleration during a vehicle impact at a specific speed, etc.) and the mechanical properties of the outer shell (including material and thickness, etc.). This deformation can be elastic deformation or inelastic deformation.

[0056] Soft-pack battery cell spacing:

[0057] For the purpose of weight reduction, the spacing between soft-pack battery cells should be minimized as much as possible, and even achieve close contact to form a suspended whole. When designing, the manufacturing tolerance and thermal expansion and contraction factors of the soft-pack battery cells need to be considered, and the spacing between soft-pack battery cells should be less than 0.5 mm.

[0058] Packaging film of soft-pack battery cell:

[0059] Soft-pack battery cells usually use aluminum-plastic film as the packaging material, and there are three thicknesses: 88 μm, 113 μm, and 152 μm. For power batteries, hard-shell soft-pack battery cells packaged with metal thin plates or reinforced soft-pack battery cells with a thickness of 152 μm are commonly used. After adopting this innovative structure, the requirements for packaging the soft-pack battery cells can be reduced, and aluminum-plastic films with a thickness of 113 μm or 88 μm can be used, thereby further reducing weight and cost.

[0060] Density of the filling liquid:

[0061] Ideally, when the density of the filling liquid is equal to the overall density of the soft-pack battery cells, the resultant force on the soft-pack battery cells is zero, and mechanical shock can be completely offset. In practical applications, there can be a certain tolerance between the density of the filling liquid and the overall density of the soft-pack battery cells, which will correspondingly affect the degree of offsetting mechanical shock. The density of the filling liquid is preferably within ±5% of the overall density of the soft-pack battery cells. If the requirements are not very high, the density of the filling liquid can also be within ±25% of the overall density of the soft-pack battery cells.

[0062] Flame retardant and fire extinguishing function of the filling liquid:

[0063] In addition, the filling liquid of this structure can also serve as a fire extinguishing agent. Currently, perfluoromethylcyclohexanone is the preferred fire extinguishing agent for lithium battery fires. This is a filling liquid with a relatively high density, and its density reaches 1.6 g / cm 3Although this density does not fully reach the approximately 2.2g / cm 3 The overall density is not as high as that of the soft-pack battery, but it is quite close. In the embodiments of the present application, a filling liquid with flame retardant and fire extinguishing effects can be selected as the gap inside the battery pack. In this case, if the battery pack explodes, the filling liquid can immediately play the role of a fire extinguishing agent. In particular, since the filling liquid always surrounds the soft-pack battery cell, it ensures that the fire extinguishing effect is immediately produced when a sudden disaster occurs, achieving zero-delay and zero-distance fire extinguishing effects, and becoming the best emergency fire fighting solution.

[0064] Optional, perfluorohexanone is a clean, environmentally friendly, non-toxic and highly effective fire extinguishing agent, it has good electrical insulation and extremely low freezing point, which is very close to the requirements of this structure. Its physical and chemical parameters are mainly density (1.6g / cm 3 ) and boiling point (49°C). Therefore, in the embodiments of the present application, a flame retardant fire extinguishing agent is used as the filling liquid in the shell, which provides an additional safety guarantee for the battery pack design. Of course, the present application does not limit the specific type of fire extinguishing agent, and other existing or future discovered fire extinguishing agents may also be used.

[0065] Production requirements:

[0066] This innovative structure mainly adds two production requirements: the sealing of the shell and the selection of the filling liquid. Specifically, for the sealing of the shell, this is a very common and mature process in the automotive industry. Whether it is a fuel tank or an engine, a lot of sealing work is involved. The sealing requirements of this structure are relatively simple, because it does not involve high temperature and high pressure environments, nor does it have relatively moving parts that need to be sealed. Conventional sealing welding or adding sealing gaskets can meet this requirement. As for the choice of filling liquid, the requirement is that the density matches the overall density of the battery. Considering that the density of lithium batteries commonly used in electric vehicles is about 2.2g / cm 3 , which is much higher than the density of water, so the so-called "heavy liquid" needs to be selected. Heavy liquids are divided into two categories: inorganic heavy liquids and organic heavy liquids, each with different physical and chemical properties. When choosing a suitable heavy liquid, it is necessary to consider its low toxicity, low corrosiveness, good fluidity and stability, while also taking into account its insulation, flame retardant and antifreeze properties, as well as economic and environmental factors. Taking all factors into consideration, the selection range of suitable heavy liquids is relatively wide and can be easily purchased according to specific needs.

[0067] More specifically, see Figure 1 The power battery pack capable of offsetting mechanical impact of this embodiment includes:

[0068] A housing 11, wherein the housing 11 is a sealed structure;

[0069] A plurality of pouch cells 13 are evenly arranged and placed inside the housing 11. Positive and negative electrodes 14 and an exhaust safety valve 16 are provided on the plurality of pouch cells 13. The positive and negative electrodes of adjacent pouch cells 13 are connected by a wire 15; and

[0070] Filling liquid 12 fills all the remaining space inside the housing 11;

[0071] The wire between the plurality of pouch cells 13 enables the connection of the positive and negative electrodes between adjacent pouch cells 13.

[0072] Optionally, one end face of the pouch cell 13 is fixedly sealed with the housing 11, and the positive and negative electrodes and the exhaust safety valve 16 of the pouch cell 13 are led out of the housing 11 from the end face where the pouch cell 13 is fixedly sealed with the housing 11.

[0073] Optionally, the density of the filling liquid 12 is substantially the same as the average density of the plurality of pouch cells 13, where substantially the same means that the difference between the two is within ±5%.

[0074] Optionally, the plurality of pouch cells 13 are arranged with a minimum gap, and the positive and negative electrodes of adjacent pouch cells 13 are connected by a wire, where the minimum gap means that the gap width is less than 0.5 mm.

[0075] Optionally, the housing 11 is a rectangular box, and the plurality of pouch cells 13 are arranged along the length direction of the housing 11.

[0076] Optionally, the gap between the housing 11 and the plurality of pouch cells 13 is 0.5 - 5 mm.

[0077] Optionally, the filling liquid 12 is a filling liquid 12 with a flame-retardant and fire-extinguishing function.

[0078] The technical effects of the above embodiments are as follows:

[0079] Protect the pouch cells, extend the life, and reduce the risk of thermal runaway: This innovative structure effectively prevents damage to the pouch cells caused by mechanical shock. In the operating environment of an automobile, continuous high-intensity mechanical shock can cause damage to the internal material structure of the pouch cells, accelerate aging, and even trigger thermal runaway. After adopting this innovative structure, the pouch cells are maintained in a floating state with a resultant force of zero, significantly extending the battery life and greatly reducing the risks of thermal runaway and deflagration caused by shock.

[0080] Reduce the manufacturing difficulty of the pouch cells: Since the pouch cells are no longer subject to mechanical shock, the requirements for their structural strength are reduced, which helps to simplify the production process, reduce costs, and at the same time improve the energy density of the pouch cells.

[0081] Simplified shell structure: In this innovative structure, no additional support beams are required in the battery pack. The uniform pressure distribution of the filling liquid means that there will be no stress concentration when the shell bears the total weight of the soft-pack battery cells, simplifying the difficulty and cost of shell production.

[0082] Reduce volume: Remove the battery reinforcement beams and hard shell, use smaller and thinner soft-pack cells, and arrange the soft-pack cells closely, which effectively reduces the volume of the battery pack and saves space for users.

[0083] Reduce weight: By removing the weight of the reinforced beam and hard shell, the optimized space layout can still effectively reduce the total weight and increase the energy density of the battery pack despite the injection of filling liquid.

[0084] Reduce total cost: This innovative structure mainly increases the filling liquid and shell sealing requirements, while other aspects are simplified designs, making the final battery pack smaller in size, lighter in weight, and more material-saving, so the total cost is lower than the existing structure.

[0085] The filling liquid can also be used as a fire extinguishing agent: Perfluorohexanone, which has a density close to that of lithium batteries, is selected as the gap filling liquid, which not only meets the structural requirements, but also can immediately play a fire extinguishing role when a battery pack explodes. This filling liquid is always around the soft-pack battery cell to ensure that the fire can be extinguished immediately and at zero distance in the event of a sudden disaster. Although perfluorohexanone is slightly insufficient in density and boiling point, its clean, environmentally friendly and non-toxic characteristics make it an ideal fire extinguishing agent choice with high feasibility.

[0086] Figure 3 A second embodiment of the present application is shown, as Figure 3 As shown, for the design of the soft-pack battery cell 32, when the positive and negative electrodes 36 are respectively arranged at both ends, if the electrode external structure is selected, it is necessary to open holes on both sides of the outer shell 31 so that the end faces of the soft-pack battery cell 32 are just matched with the outer shell 31 and exposed. This design requires that the end faces of the soft-pack battery cell 32 are tightly sealed and fixed to the outer shell to ensure that the inside of the battery pack is a sealed cavity. Under this structure, the electrodes at both ends of the soft-pack battery cell 32 and the exhaust safety valve 34 are located outside the battery pack shell, which is convenient for wiring and use. The external electrode structure has become the preferred solution due to its advantages such as simple process, safety and reliability.

[0087] More specifically, see Figure 3 The power battery pack capable of offsetting mechanical impact of this embodiment includes:

[0088] A housing 31, wherein the housing 31 is a sealed structure;

[0089] Multiple soft-pack battery cells 32, the multiple soft-pack battery cells 32 are evenly arranged and placed inside the housing 31, and positive and negative electrodes and an exhaust safety valve 34 are provided on the multiple soft-pack battery cells 32; and

[0090] Filling liquid 33, the filling liquid 33 fills all the remaining space inside the housing 31;

[0091] Wires 35 between the multiple soft-pack battery cells 32, the wires 35 realize the connection of positive and negative electrodes between adjacent soft-pack battery cells 32.

[0092] Optionally, opposite side end faces of the soft-pack battery cell 32 are hermetically fixed to the housing 31, a positive lead of the soft-pack battery cell 32 and the exhaust safety valve 34 are led out of the housing 31 from one side end face of the soft-pack battery cell 32, and a negative lead of the soft-pack battery cell 32 is led out of the housing 31 from the other side end face of the soft-pack battery cell 32.

[0093] Optionally, the density of the filling liquid 33 is substantially the same as the average density of the multiple soft-pack battery cells 32, wherein substantially the same means that the difference between the two is within ±5%.

[0094] Optionally, the multiple soft-pack battery cells 32 are arranged with a minimum gap, and the positive and negative electrodes of adjacent soft-pack battery cells 32 are connected by wires 35, wherein the minimum gap means that the gap width is less than 0.5 mm.

[0095] Optionally, the housing 31 is a rectangular box body, and the multiple soft-pack battery cells 32 are arranged along the length direction of the housing 31.

[0096] Optionally, the gap between the housing 31 and the multiple soft-pack battery cells 32 is 0.5 - 5 mm.

[0097] Optionally, the filling liquid 33 is a filling liquid 33 with a flame-retardant and fire-extinguishing function.

[0098] The first embodiment is an embodiment having the same technical concept as this embodiment. The technical details in the first embodiment can be applied to this embodiment, and the technical details in this embodiment can also be applied to the first embodiment.

[0099] The technical effects of the above embodiments are as follows:

[0100] Protect soft-pack cells, extend life, and reduce the risk of thermal runaway: This innovative structure effectively prevents mechanical shock from damaging soft-pack cells. In the operating environment of a car, continuous high-intensity mechanical shock can damage the internal material structure of the soft-pack cells, accelerate aging, and even cause thermal runaway. After adopting this innovative structure, the soft-pack cells remain in a suspended state with zero combined force, significantly extending the battery life and greatly reducing the risk of thermal runaway and deflagration caused by impact.

[0101] Reduce the difficulty of making soft-pack batteries: Since soft-pack batteries are no longer subject to mechanical impact, their structural strength requirements are reduced, which helps to simplify the production process, reduce costs, and at the same time improve the energy density of soft-pack batteries.

[0102] Simplified shell structure: In this innovative structure, no additional support beams are required in the battery pack. The uniform pressure distribution of the filling liquid means that there will be no stress concentration when the shell bears the total weight of the soft-pack battery cells, simplifying the difficulty and cost of shell production.

[0103] Reduce volume: Remove the battery reinforcement beams and hard shell, use smaller and thinner soft-pack cells, and arrange the soft-pack cells closely, which effectively reduces the volume of the battery pack and saves space for users.

[0104] Reduce weight: By removing the weight of the reinforced beam and hard shell, the optimized space layout can still effectively reduce the total weight and increase the energy density of the battery pack despite the injection of filling liquid.

[0105] Reduce total cost: This innovative structure mainly increases the filling liquid and shell sealing requirements, while other aspects are simplified designs, making the final battery pack smaller in size, lighter in weight, and more material-saving, so the total cost is lower than the existing structure.

[0106] The filling liquid can also be used as a fire extinguishing agent: Perfluorohexanone, which has a density close to that of lithium batteries, is selected as the gap filling liquid, which not only meets the structural requirements, but also can immediately play a fire extinguishing role when a battery pack explodes. This filling liquid is always around the soft-pack battery cell to ensure that the fire can be extinguished immediately and at zero distance in the event of a sudden disaster. Although perfluorohexanone is slightly insufficient in density and boiling point, its clean, environmentally friendly and non-toxic characteristics make it an ideal fire extinguishing agent choice with high feasibility.

[0107] Figure 4 The third embodiment of the present application is shown. Figure 4 As shown, in some specific scenarios, it may be necessary to consider using a structure with built-in electrodes. Figure 4Among them, the wiring between the soft-pack battery cells 43 is completed inside the battery pack, while the wiring of the total positive and negative electrodes of the battery pack is led out through the openings on the outer shell. These wire outlet holes must be sealed and fixed to maintain the sealing of the battery pack. The main challenge of this built-in structure lies in ensuring the reliability of electrical insulation. This can be achieved by using a filling liquid with good insulation properties or taking effective insulation measures for the wiring of the soft-pack battery cells 43. In addition, the design of the exhaust safety valves 45 and 46 is also a consideration point, and the exhaust lead-out method needs to be specially designed to meet the structural and functional requirements.

[0108] More specifically, referring to Figure 4 , the power battery pack capable of offsetting mechanical shock in this embodiment includes:

[0109] An outer shell 41, and the outer shell 41 is a sealed structure;

[0110] A plurality of soft-pack battery cells 43, the plurality of soft-pack battery cells 43 are evenly arranged in the outer shell 41, and positive and negative electrodes, an exhaust safety valve 45 and an exhaust safety valve 46 are provided on the plurality of soft-pack battery cells 43; and

[0111] A filling liquid 42, and the filling liquid 42 fills all the remaining spaces inside the outer shell 41;

[0112] The wires between the plurality of soft-pack battery cells 43, and the wires realize the connection of the positive and negative electrodes between adjacent soft-pack battery cells 43.

[0113] Optionally, the plurality of soft-pack battery cells 43, their positive and negative electrodes, an exhaust safety valve 45 and an exhaust safety valve 46 are all surrounded by the filling liquid 42 inside the outer shell 41, and the positive and negative electrodes of the plurality of soft-pack battery cells 43 and the exhaust safety valve 45 and the exhaust safety valve 46 are all arranged on one end face of the plurality of soft-pack battery cells 43; and,

[0114] The power battery pack further includes positive and negative bus lead-out terminals 44 on the outer shell 41, and the positive and negative bus lead-out terminals 44 are respectively electrically connected to the positive and negative electrodes of the first and last two soft-pack battery cells 43 among the plurality of soft-pack battery cells 43, so as to realize the series connection of all the soft-pack battery cells 43; and,

[0115] Insulation measures are taken for the wires between the plurality of soft-pack battery cells 43, the positive and negative electrodes of the plurality of soft-pack battery cells 43, and the contact surfaces between the plurality of soft-pack battery cells 43 and the outer shell 41 to make them insulated.

[0116] Optionally, the density of the filling liquid 42 is approximately the same as the average density of the plurality of soft-pack battery cells 43, where approximately the same means that the difference between the two is within ±5%.

[0117] Optionally, the multiple pouch cells 43 are arranged with a minimum gap therebetween, and the positive and negative electrodes of adjacent pouch cells 43 are connected by wires, wherein the minimum gap means that the gap width is less than 0.5 mm.

[0118] Optionally, the outer shell 41 is a rectangular box body, and the multiple pouch cells 43 are arranged along the length direction of the outer shell 41.

[0119] Optionally, the gap between the outer shell 41 and the multiple pouch cells 43 is 0.5 - 5 mm.

[0120] Optionally, the filling liquid 42 is a filling liquid 42 with a flame retardant and fire extinguishing effect.

[0121] The first embodiment is an embodiment with the same technical concept as this embodiment. The technical details in the first embodiment can be applied to this embodiment, and the technical details in this embodiment can also be applied to the first embodiment.

[0122] The technical effects of the above embodiments are as follows:

[0123] Protect the pouch cells, extend the service life, and reduce the risk of thermal runaway: This innovative structure effectively prevents damage to the pouch cells caused by mechanical shock. In the operating environment of an automobile, continuous high-intensity mechanical shock can cause damage to the internal material structure of the pouch cells, accelerate aging, and even trigger thermal runaway. After adopting this innovative structure, the pouch cells are maintained in a suspended state with a resultant force of zero, significantly extending the service life of the battery and greatly reducing the risks of thermal runaway and deflagration caused by shock.

[0124] Reduce the manufacturing difficulty of the pouch cells: Since the pouch cells are no longer subject to mechanical shock, the requirements for their structural strength are reduced, which helps to simplify the production process, reduce costs, and at the same time increase the energy density of the pouch cells.

[0125] Simplify the outer shell structure: In this innovative structure, no additional support cross beams need to be provided inside the battery pack. The uniform pressure distribution characteristic of the filling liquid means that the outer shell will not show stress concentration when bearing the total weight of the pouch cells, simplifying the manufacturing difficulty and cost of the outer shell.

[0126] Reduce the volume: Remove the battery strengthening cross beam and the hard shell, use pouch cells with a smaller volume and thinner packaging, and arrange the pouch cells closely, effectively reducing the volume of the battery pack and saving space for users.

[0127] Reduce the weight: Excluding the weight of the strengthening cross beam and the hard shell, although the filling liquid is injected, the optimized spatial layout can still effectively reduce the total weight and increase the energy density of the battery pack.

[0128] Reduce the total cost: What this innovative structure mainly adds are the filling liquid and the requirements for the shell seal. In other aspects, the design is simplified, making the final battery pack smaller in volume, lighter in weight, and using less material. Therefore, the total cost is lower than that of the existing structure.

[0129] The filling liquid can also serve as a fire extinguishing agent: Select perfluoromethylcyclohexane with a density close to that of lithium batteries as the gap filling liquid, which not only meets the structural requirements but also can immediately play a fire extinguishing role when the battery pack explodes and burns. This filling liquid is permanently around the soft-pack battery cells to ensure immediate and zero-distance fire extinguishing in case of sudden disasters. Although perfluoromethylcyclohexane has slight deficiencies in density and boiling point, its clean, environmentally friendly, and non-toxic characteristics make it an ideal choice for a fire extinguishing agent, with high feasibility.

[0130] It should be noted that currently, lithium batteries are commonly used in electric vehicles, and the excessive weight of the battery pack has become a major challenge. By adopting this innovative design method, a more compact arrangement of the single-layer array can be achieved, thus effectively improving the energy density of the battery pack, which is particularly suitable for installation on the vehicle chassis. Figure 5 and Figure 6 The appearance, partial enlarged view, front view, horizontal sectional view, and vertical sectional view of this example are shown, facilitating more in-depth observation and analysis.

[0131] As Figure 5 and Figure 6 shown, it uses a large-capacity rectangular soft-pack battery with single-sided electrode lead-out. The batteries are arranged in a tight single-layer array within the battery pack. The electrode lead-out ends of the batteries are in contact with and sealed to the shell. The design of the shell includes corresponding openings, making the electrodes and the exhaust safety valve located outside the battery pack. There is a very small gap between the shell and the part of the battery except the lead-out end, and the batteries are also closely arranged, only leaving a tiny gap to accommodate the installation tolerance. The shell and the lead-out ends of the batteries together form a sealed flat rectangular box, meeting the requirements for installation on the vehicle chassis. The remaining space inside the entire battery pack is filled with a filling liquid with a density equal to the overall density of the batteries. The shell structure is strong enough to bear the weight of the batteries and meet the requirements of vehicle operation. Since the batteries are suspended in the filling liquid, the buoyancy cancels out the inertial force acting on the batteries, protecting the batteries from any mechanical shock. Therefore, the batteries do not require additional structural support or a rigid hard shell, and the soft-pack shell is sufficient to ensure the insulation and isolation of the batteries.

[0132] The following is a comparison between the new structure and the current common battery structures, listing the similarities and differences according to different items:

[0133] 1) Shell strength

[0134] Current common structure: It must be strong enough to bear the weight of the batteries and maintain structural stability in the vehicle operating environment.

[0135] Innovative structure: The requirements are the same. The outer shell also needs to bear the weight of the battery and maintain structural stability.

[0136] 2) Sealing of the outer shell

[0137] Current common structure: It has a waterproof design and requires a protection level of IP67 or above.

[0138] Innovative structure: Adopts a completely sealed design to form a fully sealed box.

[0139] 3) Support crossbeam between batteries

[0140] Current common structure: A certain number of support structures are set inside the battery pack as needed to reduce the pressure on the battery.

[0141] Innovative structure: There is no need to set a support crossbeam.

[0142] 4) Strength of the soft-pack battery cell housing

[0143] Current common structure: Use a hard shell or a relatively thick soft shell (when using a soft-shell soft-pack battery cell, a support crossbeam needs to be added), and it must be able to withstand mechanical shocks and maintain structural stability.

[0144] Innovative structure: A soft shell can be used without having to withstand mechanical shocks.

[0145] 5) Sealing of the soft-pack battery cell housing

[0146] Current common structure: Completely sealed to ensure electrolyte isolation and electrical insulation.

[0147] Innovative structure: The requirements are the same, and it also needs to be completely sealed.

[0148] 6) Internal stress of the soft-pack battery cell

[0149] Current common structure: The electrode materials inside the soft-pack battery cell, etc., must be able to withstand the stress caused by the elastic deformation of the soft-pack battery cell housing.

[0150] Innovative structure: There is no stress inside the soft-pack battery cell.

[0151] 7) Lead-out electrode

[0152] Current common structure: Placed inside the battery pack.

[0153] Innovative structure: Placed outside the battery pack, an electrical junction box needs to be added, and the waterproof requirement reaches IP67 or above.

[0154] 8) Structural filling liquid

[0155] Current common structure: None.

[0156] Innovative Structure: It is necessary to fill all the remaining space inside the battery pack with a filling liquid.

[0157] In summary, this innovative structure is significantly different from the existing structure in terms of the sealing performance of the battery pack, the simplification of the internal structure, the selection of the soft-pack battery cell housing, and the internal stress, providing a more optimized solution.

[0158] Generally speaking, in terms of volume, the new structure removes the hard housing due to the use of soft-pack battery cells, and also eliminates the support crossbeam inside the battery pack. Such a design reduces the volume of the new structure by at least 3%, that is to say, the volume energy density of the entire battery pack is increased by more than 3%. In terms of weight, the hard housing and the internal support crossbeam are removed, and what is increased is the filling liquid for filling the gaps, which is equivalent to replacing the metal support material with the filling liquid. Considering that the overall density of the soft-pack battery cells is approximately 2.2 g / cm 3 , which is lower than that of steel and even aluminum alloy, the total weight of the battery pack with the new structure can thus be reduced by more than 4%, meaning that the mass energy density is also correspondingly increased by more than 4%.

[0159] It should be noted that in the application documents of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one" does not exclude the existence of another identical element in the process, method, article or device comprising the said element. In the application documents of this patent, if it is mentioned that an act is performed according to a certain element, it means at least performing the act according to that element, including two cases: performing the act only according to that element, and performing the act according to that element and other elements. Expressions such as multiple, many times, various, etc. include 2, 2 times, 2 kinds, and more than 2, more than 2 times, more than 2 kinds.

[0160] All the documents mentioned in this application are considered to be integrally included in the disclosure content of this application so that they can be used as the basis for modification when necessary. In addition, it should be understood that after reading the above disclosure content of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope protected by this application.

Claims

1. A power battery pack capable of offsetting mechanical shock, characterized in that, it includes: a housing, the housing is a sealed structure; a plurality of soft-pack battery cells, placed inside the housing, and the gap between the housing and the plurality of soft-pack battery cells is greater than the deformation of the housing under the estimated maximum shock; a filling liquid, the filling liquid fills all the remaining space inside the housing, wherein the density of the filling liquid is within ±25% of the average density of the plurality of soft-pack battery cells; and wires between the plurality of soft-pack battery cells, the wires realize the connection of positive and negative electrodes between adjacent soft-pack battery cells.

2. The power battery pack according to claim 1, characterized in that, the density of the filling liquid is substantially the same as the average density of the plurality of soft-pack battery cells.

3. The power battery pack according to claim 2, characterized in that, the soft-pack battery cell further includes an exhaust safety valve, one end face of the soft-pack battery cell is fixedly sealed with the housing, and the positive and negative electrodes and the exhaust safety valve of the soft-pack battery cell are led out of the housing from the end face where the soft-pack battery cell is fixedly sealed with the housing.

4. The power battery pack according to claim 2, characterized in that, the soft-pack battery cell further includes an exhaust safety valve, both opposite end faces of the soft-pack battery cell are fixedly sealed with the housing, the lead wire of the first electrode of the soft-pack battery cell and the exhaust safety valve are led out of the housing from one end face of the soft-pack battery cell, and the lead wire of the second electrode of the soft-pack battery cell is led out of the housing from the other end face of the soft-pack battery cell.

5. The power battery pack according to claim 1, characterized in that, the plurality of soft-pack battery cells and their positive and negative electrodes are all surrounded by the filling liquid inside the housing; and, the power battery pack further includes positive and negative bus lead-out terminals on the housing, the positive and negative bus lead-out terminals are respectively electrically connected to the positive and negative electrodes of the first and last two soft-pack battery cells among the plurality of soft-pack battery cells, so as to realize the series connection of all soft-pack battery cells; and, insulation measures are taken for the wires between the plurality of soft-pack battery cells, the positive and negative electrodes of the plurality of soft-pack battery cells, and the contact surfaces between the plurality of soft-pack battery cells and the housing to make them insulated.

6. The power battery pack according to claim 1, characterized in that, the plurality of soft-pack battery cells are arranged with the smallest gap, and the positive and negative electrodes of adjacent soft-pack battery cells are connected by wires, wherein the smallest gap refers to a gap width less than 0.5 mm.

7. The power battery pack according to claim 1, characterized in that, the housing is a rectangular box, and the plurality of soft-pack battery cells are arranged along the length direction of the housing.

8. The power battery pack according to claim 1, characterized in that, the gap between the housing and the plurality of soft-pack battery cells is between 0.5 mm and 5 mm.

9. The power battery pack according to claim 1, characterized in that, the filling liquid contains a substance component with a flame-retardant and fire-extinguishing effect.

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