Battery pack and electric vehicle

Abstract

The utility model provides a battery pack and an electric vehicle, and mainly solves the problem of potential safety hazards caused by thermal runaway of the battery pack. The battery pack comprises a box body and a battery module, the box body comprises a cover plate, an outer shell and an inner shell, the inner shell is arranged in the outer shell, a cavity between the inner shell and the outer shell is a fire fighting cavity, an inner cavity of the inner shell is a battery cavity, and the cover plate is used for sealing the fire fighting cavity and the battery cavity; the battery module is arranged in the battery cavity, and fire fighting liquid is arranged in the fire fighting cavity; an explosion venting opening is formed in the inner shell, an explosion venting part is arranged at the explosion venting opening, a smoke outlet is formed in the outer shell, thermal runaway smoke generated when a battery module in the battery cavity is in thermal runaway opens the explosion venting part, and the thermal runaway smoke is exhausted through the explosion venting opening, enters the fire fighting cavity, is treated by fire fighting liquid and is exhausted through the smoke outlet in the outer shell. And fire-fighting liquid in the fire-fighting cavity enters the battery cavity through the explosion venting opening.

Description

Technical Field

[0001] The utility model belongs to the field of batteries, and particularly relates to a battery pack and an electric vehicle. Background Art

[0002] With the wide application of lithium-ion batteries, the safe use of lithium-ion batteries has also attracted attention. Since multiple lithium-ion batteries in an electric vehicle battery pack are highly concentrated, under the influence of factors such as overcharging, over-discharging, overheating, and mechanical collision of the lithium-ion batteries, the battery diaphragm collapses and internal short circuits are caused, resulting in thermal runaway. After the battery pack undergoes thermal runaway, not only a large amount of thermal runaway flue gas will be generated, but also the battery may catch fire internally, posing a safety hazard. Summary of the Invention

[0003] To solve the problem of safety hazards caused by thermal runaway of the battery pack, the utility model provides a battery pack and an electric vehicle.

[0004] To achieve the above object, the technical solution of the utility model is as follows:

[0005] A battery pack includes a box body and a battery module; the box body includes a cover plate, an outer shell, and an inner shell. The inner shell is arranged inside the outer shell, and the cavity between the inner shell and the outer shell is a fire protection cavity. The inner cavity of the inner shell is a battery cavity. The cover plate is used to seal the fire protection cavity and the battery cavity. The inner shell is provided with a pressure relief port communicating the fire protection cavity and the battery cavity, and a pressure relief part is arranged on the pressure relief port. The outer shell is provided with a smoke exhaust port for discharging the thermal runaway flue gas from the box body. The battery module is arranged in the battery cavity. The fire protection cavity is filled with fire protection liquid, and the liquid level height of the fire protection liquid is greater than the opening height of the pressure relief port and less than the opening height of the smoke exhaust port.

[0006] Further, a partition is arranged in the battery cavity. The partition divides the battery cavity into a battery compartment and a safety compartment. The single cells of the battery module are arranged in the battery compartment, and the battery management module of the battery module is arranged in the safety compartment.

[0007] Further, both the outer shell and the inner shell are cylindrical structures with one end open and the other end having a bottom plate. The fire protection cavity includes an annular cavity between the side walls of the outer shell and the inner shell and a cavity between the bottom plates of the outer shell and the inner shell.

[0008] Further, the cover plate includes a first end cover and an annular cover plate. The annular cover plate is arranged on the top of the annular cavity to seal the fire protection cavity. The size of the first end cover is the same as the size of the open end of the outer shell, and is used to seal the open end of the outer shell.

[0009] Further, the pressure relief port is arranged at the bottom of the inner shell, and the pressure relief part on the pressure relief port is a pressure relief membrane.

[0010] Further, the smoke exhaust port of the outer casing is provided at the top of the outer casing, and a one-way valve for discharging the smoke of thermal runaway is provided on the smoke exhaust port.

[0011] Further, a U-shaped pipe is provided between the smoke exhaust port and the one-way valve, and the installation height of the U-shaped pipe is greater than the height of the smoke exhaust port.

[0012] Further, a smoke exhaust pipeline is also provided on the outer casing, the smoke exhaust pipeline is connected to the one-way valve, the length of the smoke exhaust pipeline is greater than 0.2 m, and the outlet of the smoke exhaust pipeline is arranged downward.

[0013] Further, the fire extinguishing liquid is water.

[0014] The present utility model also provides an electric vehicle, which includes the above-mentioned battery pack, and the battery pack is arranged on the frame of the electric vehicle.

[0015] Compared with the prior art, the technical solution of the present utility model has the following advantages:

[0016] 1. In the battery pack of the present utility model, the box body is of a double-shell structure, and the double-shell structure forms a battery cavity and a fire extinguishing cavity. The battery module is installed in the battery cavity, and the fire extinguishing liquid is provided in the fire extinguishing cavity. When thermal runaway occurs in the battery module in the battery cavity, the smoke of thermal runaway opens the explosion relief part on the explosion relief port. After the smoke of thermal runaway is discharged through the explosion relief port, it enters the fire extinguishing cavity. The fire extinguishing liquid in the fire extinguishing cavity cools the smoke of thermal runaway, so that the temperature of the smoke of thermal runaway discharged from the box body is reduced and it is not easy to catch fire. At the same time, when the smoke of thermal runaway passes through the fire extinguishing liquid, the electrolyte and some combustible gases in the smoke of thermal runaway are adsorbed in the fire extinguishing liquid, further reducing the probability of the smoke of thermal runaway catching fire. The processed smoke of thermal runaway is discharged through the smoke exhaust port on the outer casing.

[0017] Since there is an obvious time interval for thermal runaway of each single battery in the battery module, therefore, after the smoke of thermal runaway is discharged from the battery cavity and the battery cavity is depressurized, under the action of the liquid level difference, the fire extinguishing liquid in the fire extinguishing cavity can enter the battery cavity through the explosion relief port to cool and extinguish the battery module, avoiding continuous thermal runaway of the battery module, preventing the spread of thermal runaway, and improving the safety of the battery pack.

[0018] 2. In the battery pack of the present utility model, a partition is provided in the battery cavity, and the partition isolates the single battery of the battery module from the battery management module, preventing the battery management module from being damaged when the single battery has thermal runaway, thereby improving the safety of the battery pack.

[0019] 3. In the battery pack of the present utility model, both the outer casing and the inner casing are cylindrical structures with one end open and one end having a bottom plate. This kind of structure of the outer casing and the inner casing with one end open can improve the sealing performance between the battery cavity and the fire extinguishing cavity, and at the same time, it is also convenient for the cover plate to seal the fire extinguishing cavity and the battery cavity.

[0020] 4. In the battery pack of the present invention, the cover plate includes a first end cover and an annular cover plate. The annular cover plate is used to seal the fire-fighting cavity, and the first end cover is used to seal the open end of the outer shell. This cover plate structure can seal the fire-fighting cavity twice, reducing the probability of leakage of the fire-fighting fluid in the fire-fighting cavity. At the same time, after the cover plate of this structure is set on the inner shell and the outer shell, it is convenient for the installation of devices in the fire-fighting cavity and the battery cavity, and it also has aesthetics.

[0021] 5. In the battery pack of the present invention, the explosion vent is set on the bottom of the inner shell to facilitate the injection of fire-fighting fluid and promptly prevent the spread of thermal runaway. At the same time, when the thermal runaway smoke is discharged through the explosion vent on the bottom of the inner shell, the bottom plate of the outer shell can also buffer and reduce the pressure of the thermal runaway smoke to a certain extent, thereby preventing the thermal runaway smoke from impacting the fire-fighting fluid in the fire-fighting chamber.

[0022] 6. In the battery pack of the present invention, the smoke exhaust port of the outer shell is arranged at the top of the outer shell. This arrangement allows the thermal runaway smoke to be discharged smoothly. At the same time, a one-way valve is provided on the smoke exhaust port to discharge the thermal runaway smoke. The one-way valve has a certain opening pressure. When the battery pack is working normally, the one-way valve seals the smoke exhaust port and at the same time prevents the fire-fighting fluid in the fire-fighting chamber from volatilizing. When the battery module suffers from thermal runaway, the thermal runaway smoke with a certain pressure opens the one-way valve and is discharged through the smoke exhaust port.

[0023] 7. In the battery pack of the present invention, if the pressure of the thermal runaway smoke gas discharged through the explosion vent is high, the fire-fighting fluid in the fire-fighting chamber may be squeezed out of the box through the smoke exhaust port by the thermal runaway smoke gas. In this case, a U-shaped tube is provided between the smoke exhaust port and the one-way valve. The U-shaped tube can prevent the fire-fighting fluid from being discharged through the one-way valve.

[0024] 8. In the battery pack of the present invention, a smoke exhaust pipe is connected to the smoke exhaust port. The smoke exhaust pipe is a pipe of a certain length. The smoke exhaust pipe spatially isolates the discharged thermal runaway smoke from the battery pack, so that the discharged thermal runaway smoke has a certain safety distance from the battery pack, avoiding the thermal runaway smoke from affecting the battery module in the box after being discharged.

[0025] 9. In the battery pack of the present invention, the outlet of the smoke exhaust pipe is set downward so that the thermal runaway smoke can be discharged smoothly and promptly. At the same time, the outlet of the smoke exhaust pipe is set downward so that its exhaust direction is toward the ground, avoiding the discharged thermal runaway airflow from burning passengers or damaging the electric vehicle.

[0026] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0028] Figure 1 Schematic diagram of the structure of the battery pack in Embodiment 1 of the present invention;

[0029] Figure 2 Exploded view of the battery pack in Embodiment 1 of the present invention;

[0030] Figure 3 Schematic diagram of the structure of the battery module in Embodiment 1 of the present invention;

[0031] Figure 4 Cross-sectional view of the battery pack in Embodiment 1 of the present invention;

[0032] Figure 5 Schematic diagram of the box structure of the battery pack in Embodiment 1 of the present invention;

[0033] Figure 6 Schematic diagram of the battery pack (with a smoke exhaust pipeline) in Embodiment 1 of the present invention;

[0034] Figure 7 Schematic diagram of the battery pack (with a U-shaped pipe) in Embodiment 1 of the present invention;

[0035] Figure 8 Schematic diagram of the structure of the battery pack in Embodiment 2 of the present invention;

[0036] Figure 9 Cross-sectional view of the battery pack in Embodiment 2 of the present invention;

[0037] Figure 10 Schematic diagram of the box structure of the battery pack in Embodiment 2 of the present invention;

[0038] Figure 11 Schematic diagram of the structure of the electric vehicle in Embodiment 3 of the present invention;

[0039] Figure 12 Schematic diagram of the installation of the battery pack on the electric vehicle in Embodiment 4 of the present invention.

[0040] Reference numerals: 100 - battery pack, 200 - electric vehicle, 1 - box body, 2 - battery module, 3 - one - way valve, 4 - smoke exhaust pipeline, 5 - U - shaped pipe, 11 - inner shell, 12 - outer shell, 13 - battery cavity, 14 - fire protection cavity, 15 - cover plate, 16 - explosion venting part, 17 - partition board, 111 - explosion vent, 112 - smoke exhaust port, 151 - first end cover, 152 - annular cover plate, 21 - single cell, 22 - battery management module, 23 - terminal, 24 - fixing bracket, 25 - insulating plate, 26 - U - shaped connecting plate, 27 - connecting rod. Detailed implementation manners

[0041] To make the above - mentioned objects, features, and advantages of the present utility model more obvious and understandable, the following provides a detailed description of the specific implementation manners of the present utility model with reference to the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present utility model, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0042] The "in other embodiments" that appear in different places in this specification do not all refer to the same embodiment, nor are they separate or selectively exclusive embodiments from other embodiments. In the description of this specification, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. In the description of the present utility model, the meaning of "a plurality of" is two or more, unless otherwise specifically defined.

[0043] In the description of this specification, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate member, or it can be the internal communication of two components. For those of ordinary skill in the art, the specific meaning of the above - mentioned terms in the present utility model can be understood according to specific circumstances.

[0044] At the same time, in the description of the present utility model, it should be noted that the orientation or positional relationship indicated by terms such as "top, bottom, inner, and outer" is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present utility model.

[0045] Existing battery packs generally include multiple single cells, which are closely arranged in the box of the battery pack. During the use of the battery pack, or in the case of overcharging, over-discharging, and mechanical collision, thermal runaway is likely to occur. When thermal runaway occurs in the battery pack, a series of chemical reactions will occur inside, releasing a large amount of heat and gas, posing a safety hazard. Based on this, the box of the battery pack of the present utility model is set as a double-layer shell structure. This double-shell structure forms a battery chamber and a fire protection chamber surrounding the outer periphery of the battery chamber. The battery module is arranged in the battery chamber, and fire protection liquid is provided in the fire protection chamber.

[0046] When the battery module in the battery chamber is working normally, since the fire protection chamber surrounds the battery chamber, at this time, the fire protection liquid in the fire protection chamber exchanges heat with the battery module in the battery chamber in multiple areas, making the temperature of the battery module in the battery chamber more balanced and reducing the probability of thermal runaway of the battery module.

[0047] When thermal runaway occurs in the battery module in the battery chamber, the thermal runaway flue gas opens the explosion vent part on the explosion vent. After the thermal runaway flue gas is discharged through the explosion vent, it enters the fire protection chamber. The fire protection liquid in the fire protection chamber cools down the thermal runaway flue gas, so that the temperature of the thermal runaway flue gas discharged from the box is reduced and it is not easy to catch fire. At the same time, when the thermal runaway flue gas passes through the fire protection liquid, the electrolyte and some combustible gases in the thermal runaway flue gas are adsorbed in the fire protection liquid, further reducing the probability of the thermal runaway flue gas catching fire. The treated thermal runaway flue gas is discharged through the smoke exhaust port on the outer shell, avoiding the safety hazard caused by the discharge of the thermal runaway flue gas from the battery pack. In addition, due to the obvious time interval of thermal runaway of the single cells in the battery module, the thermal runaway flue gas is discharged from the battery chamber, and the battery chamber is depressurized. At this time, based on the principle of liquid level difference, the fire protection liquid in the fire protection chamber enters the battery chamber through the explosion vent to treat the thermally runaway battery in the battery chamber, so as to prevent the spread of thermal runaway and improve the safety of the battery pack.

[0048] Finally, the box with the above double-shell structure can protect the battery module. When the box is subjected to external impact force or mechanical collision, the double-layer shell can protect the battery module and reduce the probability of thermal runaway of the battery module.

[0049] Embodiment 1

[0050] As Figures 1 to 4As shown in the figure, the battery pack 100 provided in this embodiment includes a box body 1 and a battery module 2. The battery module 2 is the main power supply of the battery pack 100, mainly including a battery management module 22 and a plurality of single cells 21. The plurality of single cells 21 are connected in series to meet different capacity requirements of the battery pack 100. The single cell 21 can be an existing single cylindrical battery, square shell battery, or soft pack battery. The battery management module 22 (BMS) mainly monitors the working states of the respective single cells 21. The battery module 2 is electrically connected to an external circuit or an electrical device through a wiring terminal 23. The wiring terminal 23 can be disposed on the box body 1 and exposed from the box body 1, facilitating charging and discharging. During installation, the wiring terminal 23 can be fixedly connected to the box body 1 and non-detachable from the box body 1, or can be detachably connected to the box body 1. At the same time, insulation needs to be ensured between the wiring terminal 23 and the box body 1. For example, after the wiring terminal is fixed on the box body 2, an insulating sleeve or insulating layer is provided between the wiring terminal and the box body 1.

[0051] As Figure 3 shown in the figure, the battery module 2 in this embodiment mainly includes two groups of cylindrical batteries. Each group of cylindrical batteries includes 24 cylindrical batteries. Among them, every 4 cylindrical batteries are arranged in a row, with a total of 6 rows. Fixing frames 24 are provided on both sides of each group of cylindrical batteries. The two fixing frames 24 fix the 24 cylindrical batteries into a group. After being fixed into a group, the respective cylindrical batteries in each group of cylindrical batteries are electrically connected through electrical connection pieces. After each group of cylindrical batteries is grouped and electrically connected, the two groups of cylindrical batteries are arranged side by side and electrically connected through electrical connection members. At the same time, an insulating plate 25 is provided between the two groups of cylindrical batteries to improve the safety between the two groups of cylindrical batteries. Finally, the two groups of cylindrical batteries are assembled through a U-shaped connecting plate 26 and a connecting rod 27. During specific connection, the two connecting rods 27 respectively pass through the four fixing frames 24 of the two groups of cylindrical batteries, one end of which is fixedly connected to a vertical plate of the U-shaped connecting plate 26, and the other end is fixedly connected to the other vertical plate of the U-shaped connecting plate 26. The two groups of cylindrical batteries are integrated into a whole through the U-shaped connecting plate 26 and the connecting rod 27, facilitating overall installation and disassembly.

[0052] The above-mentioned battery module 2 is disposed in the box body 1 and needs to be insulated from the box body 1. Specifically, an insulating film can be coated on the outer side of the battery module 2, or an insulating pad can be provided between the battery module and the box body 1, or the box body 1 is made of an insulating material, etc. The box body 1 is a closed box body, mainly for integrally installing the battery module 2 and also for protecting the safety of the battery module 2, so that the battery module 2 is protected from impacts, vibrations, drops, etc. in the external environment. The shape and size of the box body 1 can be designed according to the application scenario of the battery module 2 into a shape convenient for placement, such as a cylinder, prism, cube, etc. For the convenience of installation and placement, the box body 1 is generally a rectangular box body structure.

[0053] As Figure 2 andFigure 4 As shown, the box body 1 in this embodiment includes a housing and a cover plate 15. The housing is a double-housing structure, including an outer housing 12 and an inner housing 11. The inner housing 11 is arranged inside the outer housing 12. The cavity between the inner housing 11 and the outer housing 12 is a fire protection cavity 14, and the fire protection cavity 14 is filled with fire protection liquid. The inner cavity of the inner housing 11 is a battery cavity 13. The cover plate 15 is arranged at the open ends of the inner housing 11 and the outer housing 12 to seal the battery cavity 13 and the fire protection cavity 14.

[0054] As Figure 5 As shown, both the inner housing 11 and the outer housing 12 in this embodiment are rectangular housing structures with one open end and one end provided with a bottom plate. During installation, the inner housing 11 is arranged inside the outer housing 12. At this time, the inner cavity of the inner housing 11 is the battery cavity 13 for installing the battery module 2, and the cavity between the inner housing 11 and the outer housing 12 is the fire protection cavity 14. The fire protection cavity 14 includes an annular cavity between the side walls of the inner housing 11 and the side walls of the outer housing 12 and a cavity between the bottom plate of the inner housing 11 and the bottom plate of the outer housing 12.

[0055] In other embodiments, the above-mentioned inner housing 11 and outer housing 12 may also be structures with both ends open. After placing the inner housing 11 inside the outer housing 12, the two open ends are respectively sealed by two cover plates 15. For this structure of the inner housing 11 and outer housing 12 with both ends open, the formed fire protection cavity 14 only includes the annular cavity, and the amount of fire protection liquid filled in the annular cavity is relatively small. At the same time, the requirements for the sealing performance of the two cover plates 15 are higher.

[0056] To ensure the sealing performance between the battery cavity 13 and the fire protection cavity 14, both the inner housing 11 and the outer housing 12 in this embodiment adopt a structure with one open end and one end having a bottom plate. At this time, only one cover plate 15 is needed to seal the battery cavity 13 and the fire protection cavity 14. The cover plate 15 can be realized by the following structure:

[0057] First, the cover plate 15 only includes a first end cover 151. The size of the first end cover 151 is the same as the size of the open end of the outer housing 12. It is arranged at the open end of the outer housing 12, which can not only seal the battery cavity 13 but also seal the fire protection cavity 14.

[0058] In the cover plate 15 of this structure, it is required that the tops of the inner housing 11 and the outer housing 12 are on the same plane to be able to seal the battery cavity 13 and the fire protection cavity 14 at the same time. If there are machining errors at the tops of the inner housing 11 and the outer housing 12, it is possible that the fire protection liquid in the fire protection cavity 14 enters the battery cavity 13.

[0059] Second, the cover plate 15 includes a second end cover and an annular cover plate 152. The size of the second end cover is the same as that of the open end of the inner housing 11. It is arranged at the open end of the inner housing 11 to seal the battery chamber 13. The annular cover plate 152 is arranged at the top of the annular cavity between the open end of the inner housing 11 and the open end of the outer housing 12 to seal the fire protection chamber 14.

[0060] Third, as Figure 5 shown, the cover plate 15 includes a first end cover 151 and an annular cover plate 152. The annular cover plate 152 is arranged at the top of the annular cavity between the open end of the inner housing 11 and the open end of the outer housing 12 to seal the fire protection chamber 14. The size of the first end cover 151 is the same as that of the open end of the outer housing 12 to seal the open end of the outer housing 12.

[0061] Compared with the cover plate 15 of the above first structure and second structure, the cover plate 15 of the third structure can seal the fire protection chamber 14 twice, reducing the possibility of fire protection liquid leakage in the fire protection chamber 14. At the same time, after the cover plate 15 of this structure is arranged on the inner housing 11 and the outer housing 12, the whole box body 1 is convenient for processing and manufacturing, convenient for installing devices in the fire protection chamber 14 and the battery chamber 13, and is also relatively beautiful.

[0062] In addition, a positioning structure can be arranged in the battery chamber 13 to position and install the battery module 2, and at the same time, it also prevents the battery module 2 from shaking greatly in the box body 1. In addition, a flame retardant material can also be filled in the battery chamber 13, and the battery module 2 is coated with the flame retardant fuel. The flame retardant material not only prevents the spread of thermal runaway in the battery compartment, but also further prevents the battery compartment from catching fire.

[0063] In this embodiment, a fire protection liquid is filled in the fire protection chamber 14. The fire protection liquid can specifically adopt fire protection liquids such as fluorinated liquid and water. When setting the liquid level height of the fire protection liquid, it needs to be greater than the opening height of the explosion vent and less than the opening height of the smoke exhaust port. At the same time, since the individual batteries in the battery chamber 13 are closely arranged, and there are also components for fixing the individual batteries and electrical connection components in the battery chamber 13, etc., the gaps in the battery chamber 13 are small. When filling the fire protection liquid, it is only necessary to make the filling height of the fire protection liquid greater than the height of the top cylindrical battery in the battery module. When the hot runaway smoke exhausts from the battery chamber 13 and the battery chamber 13 is depressurized, based on the principle of liquid level difference, the fire protection liquid in the fire protection chamber 14 enters the battery chamber 13 through the explosion vent to prevent the battery module in the battery chamber 13 from continuing to have thermal runaway.

[0064] In this embodiment, as Figure 5As shown in the figure, the above-mentioned inner housing 11 is also provided with a pressure relief opening 111 that communicates the battery chamber 13 and the fire protection chamber 14. A pressure relief part 16 is provided on the pressure relief opening 111. The pressure relief part 16 specifically adopts a pressure relief membrane or a pressure relief valve, etc. When the battery pack 100 is in normal use, the pressure relief part 16 seals the pressure relief opening 111 to prevent the fire protection liquid in the fire protection chamber 14 from entering the battery chamber 13. When the battery module 2 in the battery chamber 13 undergoes thermal runaway and the pressure in the battery chamber 13 reaches a certain value, the pressure relief part 16 is opened, and the thermal runaway flue gas is discharged through the pressure relief opening 111 and enters the fire protection chamber 14. At the same time, the fire protection liquid in the fire protection chamber 14 enters the battery chamber 13.

[0065] The above-mentioned pressure relief opening 111 can be provided on the side wall of the inner housing 11 or on the bottom plate of the inner housing 11. Preferably, the pressure relief opening 111 is provided on the bottom plate of the inner housing 11, which is convenient for pouring the fire protection liquid. At the same time, when the thermal runaway flue gas is discharged through the pressure relief opening on the inner housing 11, the bottom plate of the outer housing 12 can also buffer and decompress the thermal runaway flue gas to avoid the thermal runaway flue gas impacting and squeezing the fire protection liquid in the fire protection chamber.

[0066] At the same time, after the thermal runaway flue gas in the battery chamber 13 is discharged through the pressure relief opening 111, it is discharged through the smoke exhaust port 112 provided on the outer housing 12 after being treated by the fire protection liquid. In this embodiment, the above-mentioned smoke exhaust port 112 is provided at the top of the fire protection chamber 14, so that the thermal runaway flue gas in the battery chamber 13 can be discharged smoothly and quickly, and at the same time, the fire protection liquid in the fire protection chamber 14 is not likely to leak from the smoke exhaust port 112.

[0067] As Figure 4 shown in the figure, a one-way valve 3 can also be installed at the smoke exhaust port 112 of the outer housing 12. The one-way valve 3 has a certain opening pressure. When the battery pack is working normally, it can seal the fire protection liquid in the fire protection chamber 14 to avoid the influence of external gas or air on the fire protection liquid in the fire protection chamber 14, and at the same time, it also avoids the volatilization of the fire protection liquid in the fire protection chamber 14. When the battery module 2 undergoes thermal runaway, the thermal runaway flue gas with pressure opens the one-way valve 3, and the thermal runaway flue gas is discharged through the smoke exhaust port 112.

[0068] As Figure 6As shown, to facilitate the discharge of thermal runaway smoke within the battery cavity 13, a smoke exhaust pipe 4 is connected to the smoke exhaust port 112. The inlet of the smoke exhaust pipe 4 is connected to the smoke exhaust port 112. The smoke exhaust pipe 4 is a pipe of a certain length, which safely isolates the battery pack 100 from the discharged thermal runaway smoke, so that the discharged thermal runaway smoke does not affect the battery pack 100. In the specific configuration, it is relatively preferred that the length of the smoke exhaust pipe 4 is greater than 0.2m. This type of smoke exhaust pipe 4 increases the distance between the discharged thermal runaway smoke and the battery module 2, preventing the discharged thermal runaway smoke from affecting the battery module 2 within the battery cavity 13, and further improving the safety of the battery pack.

[0069] If multiple single cells 21 in the battery module experience thermal runaway at the same time, the pressure of the thermal runaway smoke discharged from the explosion vent 111 will be relatively high. If the high-pressure thermal runaway smoke enters the fire fighting chamber 14 through the explosion vent, the fire fighting liquid in the fire fighting chamber 14 may be squeezed out of the box through the exhaust port 112 by the thermal runaway smoke. Figure 7 As shown, in this embodiment, a U-shaped tube 5 is provided between the smoke exhaust port 112 and the one-way valve 3. The U-shaped tube 5 is installed in reverse, and the two vertical tubes of the U-shaped tube 5 are respectively connected to the smoke exhaust port 112 and the one-way valve 3. At this time, the installation height of the U-shaped tube 5 needs to be greater than the height of the smoke exhaust port 112. The U-shaped tube 5 can prevent the fire-fighting liquid in the fire-fighting chamber 14 from being squeezed out of the fire-fighting chamber, thereby improving the safety of the battery pack during use.

[0070] In addition, in the battery module, there is a clear interval time for the heat spread between the single cells 21. If only one single cell 21 experiences thermal runaway, the pressure of its thermal runaway smoke is relatively small. At this time, the fire-fighting liquid in the fire-fighting chamber 14 will not be squeezed out of the box through the exhaust port 112 by the thermal runaway smoke, or only a small amount of fire-fighting liquid will be squeezed out of the box, which does not affect its fire-fighting effect on the battery module. In this case, the above-mentioned U-shaped tube 5 may not be provided.

[0071] When manufacturing the above-mentioned battery pack 100, first, each single cell 21 is placed in the battery cavity 13, and electrical connections are made between each single cell 21, as well as between each single cell 21 and the battery management module 22 and the terminal 23. Secondly, the cover 15 is set on the top of the outer shell 12 and the inner shell 11. Then, the fire-fighting liquid is filled into the fire-fighting cavity 14 through the smoke exhaust port 112. Finally, the one-way valve 3 is installed on the smoke exhaust port 112.

[0072] After the battery pack 100 is manufactured, when one or more of the single cells in the battery chamber 13 undergo thermal runaway, when the pressure in the battery chamber 13 continuously rises to the opening pressure of the explosion vent part 16 on the explosion vent 111, the explosion vent part 16 on the explosion vent 111 opens, and the hot runaway flue gas in the battery chamber 13 enters the fire protection chamber 14 through the explosion vent 111, and the hot runaway flue gas is discharged through the smoke exhaust port 112 after being treated by the fire protection liquid.

[0073] At the same time, in the existing electric vehicle battery pack 100, the electrical connections of the single cells are generally in series. When a single cell 21 undergoes thermal runaway, there is an obvious time interval for the thermal spread between the single cells 21. Therefore, after any number of single cells 21 undergo thermal runaway, there is a certain time interval until the next single cell undergoes thermal runaway. During this interval period, the hot runaway flue gas generated by the thermally runaway single cell is discharged from the battery chamber 13, and the battery chamber 13 is depressurized. At this time, due to the liquid level difference between the fire protection liquid in the fire protection chamber 14 and the battery chamber 13, the fire protection liquid in the fire protection chamber 14 enters the battery chamber 13 through the explosion vent 111 to prevent the spread of thermal runaway and avoid the continuous thermal runaway of the single cells 21 in the battery pack 100, thereby improving the safety of the entire battery pack 100.

[0074] Embodiment 2

[0075] As Figures 8 to 10 shown, the battery pack 100 in this embodiment is similar to the battery pack 100 in Embodiment 1. In the box body 1 of the battery pack 100 in this embodiment, a partition 17 is provided in the battery chamber 13, and the partition 17 divides the battery chamber 13 into a battery compartment and a safety compartment. The single cells 21 of the battery module 2 are arranged in the battery compartment, and the battery management module of the battery module 2 is arranged in the safety compartment. Specifically, the battery compartment and the safety compartment can be arranged side by side or one above the other, and are specifically arranged according to the usage scenario and size of the battery pack 100.

[0076] After the battery pack 100 in this embodiment isolates the battery module 2 and the battery management module 22 through the partition 17, when the cable in the battery management module 22 is connected to the single cell 21 in the battery compartment, it needs to pass through the partition 17. When the cable passes through the partition 17, the tightness here needs to be ensured. In this embodiment, high-temperature waterproof cables are used, and the interface is sealed with a high-pressure gland.

[0077] In addition, a positioning structure can be provided in the battery compartment to position and install the battery module 2, and at the same time, it also prevents the battery module 2 from shaking greatly in the box body 1. In addition, a flame retardant material can also be filled in the above-mentioned battery compartment, and the battery module 2 is coated with the flame retardant fuel. The flame retardant material not only prevents the spread of thermal runaway in the battery compartment, but also further prevents the battery compartment from catching fire.

[0078] The above battery pack 100 is a battery pack that integrates adsorption treatment and liquid filling treatment. A sandwich layer is made outside the battery module 2 of this battery pack, and fire extinguishing liquid is injected into this sandwich layer. A pressure relief membrane is provided at the bottom. When a single battery undergoes thermal runaway, the pressure relief membrane opens, and the hot gas of thermal runaway will undergo the process of condensation, impurity removal, and adsorption in the fire extinguishing liquid, and finally the treated safe gas is discharged through the smoke exhaust port 112.

[0079] Embodiment 3

[0080] As Figure 11 and Figure 12 As shown, this embodiment provides an electric vehicle 200, which includes the battery pack 100 in Embodiment 1 or Embodiment 2. When in use, the battery pack 100 is installed on the vehicle body of the electric vehicle 200 to supply power to the electrical devices of the electric vehicle 200. The battery pack 100 can be installed under the seat of the electric vehicle 200. After installation, the outlet of the smoke exhaust pipeline 4 is located at the position of the rear wheel of the electric vehicle 200, and the outlet of the smoke exhaust pipeline 4 faces downward, having a safe distance from the driver.

[0081] When the battery pack 100 is charged, it can be removed from the electric vehicle 200 and placed in a charging cabinet for charging, or it can be directly placed on the electric vehicle 200 for charging on a charging pile. When any single battery 21 in the battery pack 100 undergoes thermal runaway during the charging process, the battery management module 22 monitors the abnormal state of the battery pack 100 and issues a warning message (the warning light flashes or the buzzer sounds an alarm). At the same time, the hot gas of thermal runaway opens the pressure relief part 16 on the pressure relief port 111, the battery chamber 13 is depressurized, and the hot gas of thermal runaway in the battery chamber 13 enters the fire extinguishing chamber 14 through the pressure relief port 111. After being treated by the fire extinguishing liquid, the hot gas of thermal runaway is discharged through the smoke exhaust port 112. At the same time, after the battery chamber 13 is depressurized, the fire extinguishing liquid in the fire extinguishing chamber 14 enters the battery chamber 13 to cool down and extinguish the fire of the battery module 2 in the battery chamber 13, etc., to prevent the spread of thermal runaway.

Claims

1. A battery pack, characterized in that, It includes a box body and a battery module; The box body includes a cover plate, an outer shell and an inner shell. The inner shell is arranged inside the outer shell, and the cavity between the inner shell and the outer shell is a fire protection cavity. The inner cavity of the inner shell is a battery cavity. The cover plate is used to seal the fire protection cavity and the battery cavity; The inner shell is provided with an explosion vent communicating the fire protection cavity and the battery cavity, and an explosion vent part is arranged on the explosion vent. The outer shell is provided with a smoke exhaust port for the hot runaway flue gas to discharge from the box body; The battery module is arranged in the battery cavity. Fire protection liquid is arranged in the fire protection cavity. The liquid level height of the fire protection liquid is greater than the opening height of the explosion vent and less than the opening height of the smoke exhaust port.

2. The battery pack according to claim 1, characterized in that, A partition is arranged in the battery cavity. The partition divides the battery cavity into a battery compartment and a safety compartment. The single cells of the battery module are arranged in the battery compartment, and the battery management module of the battery module is arranged in the safety compartment.

3. The battery pack according to claim 1, wherein Both the outer shell and the inner shell are cylindrical structures with one end open and the other end having a bottom plate. The fire protection cavity includes an annular cavity between the side wall of the outer shell and the side wall of the inner shell and a cavity between the bottom plate of the outer shell and the bottom plate of the inner shell.

4. The battery pack according to claim 3, wherein The cover plate includes a first end cover and an annular cover plate. The annular cover plate is arranged on the top of the annular cavity to seal the fire protection cavity. The size of the first end cover is the same as the size of the open end of the outer shell and is used to seal the open end of the outer shell.

5. The battery pack according to claim 3, wherein The explosion vent is arranged at the bottom of the inner shell, and the explosion vent part on the explosion vent is an explosion vent membrane.

6. The battery pack according to any one of claims 1 to 5, characterized in that The smoke exhaust port of the outer shell is arranged at the top of the outer shell, and a one-way valve for discharging the hot runaway flue gas is arranged on the smoke exhaust port.

7. The battery pack according to claim 6, wherein A U-shaped pipe is arranged between the smoke exhaust port and the one-way valve, and the installation height of the U-shaped pipe is greater than the height of the smoke exhaust port.

8. The battery pack according to claim 7, wherein A smoke exhaust pipeline is also arranged on the outer shell. The smoke exhaust pipeline is connected to the one-way valve. The length of the smoke exhaust pipeline is greater than 0.2 m, and the outlet of the smoke exhaust pipeline is arranged downward.

9. The battery pack according to claim 8, wherein The fire protection liquid is water.

10. An electric vehicle, characterized in that, It includes the battery pack according to any one of claims 1 to 9. The battery pack is arranged on the frame of an electric vehicle.

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