Patent Description:
In recent years, a rechargeable battery pack has been widely applied to power vehicles. A plurality of battery units in a battery pack are connected in a series, parallel, or hybrid manner to achieve a greater capacity or power.

The battery units in a current battery are in a space isolated from the outside, when the battery units suffer from thermal runway, the ejected sparks and hot air are both diffused in the compartment where the battery units are located. Since the battery units are in a limited compartment space, the ejected sparks and hot air after thermal runaway of the battery unit will rapidly raise the temperature within the compartment, especially at a position near the battery units suffering from thermal runaway, and the temperature often exceeds a triggering temperature upon thermal runaway of the battery units. At the same time, the sparks ejected from the battery units suffering from thermal runaway might splash to the surrounding battery units, which is likely to cause that the surrounding batteries successively suffer from thermal runaway, thereby creating a chain reaction so that there is a great potential safety hazard.

From <CIT> there is known a battery pack, comprising a box assembly a plurality of restraint assemblies, disposed within the box assembly, wherein each of the plurality of restraint assemblies is internally provided with an accommodating cavity, a exhaust passage is provided between the restraint assembly and the box assembly and the restraint assembly is provided with a communication hole which communicates the accommodating cavity with the exhaust passage and a plurality of battery modules, respectively disposed within the accommodating cavities of the plurality of restraint assemblies.

According to one aspect of the embodiments of the present disclosure, a battery pack as defined in claim <NUM> is provided. The battery pack including:.

The box assembly is internally provided with a plurality of fixed beams, the restraint assembly is fixed to two adjacent fixed beams, and the first exhaust passage is formed among the restraint assembly, the box assembly and the two adjacent fixed beams.

In some embodiments, the battery module includes a plurality of battery units, each of the plurality of battery units is provided with a first explosion-proof valve; and
a second exhaust passages is provided between the restraint assembly and the battery module, each of the first explosion-proof valves faces the second exhaust passage, and the communication hole communicates the second exhaust passage with the first exhaust passage.

In some embodiments, the battery pack further including: a fireproof member disposed between the restraint assembly and the battery module and covering the first explosion-proof valve of each of the plurality of battery units, wherein a second exhaust passage is formed between the fireproof member and the battery module.

In some embodiments, the restraint assembly is provided with a plurality of the communication holes, each of which is in one-to-one correspondence with each of the first explosion-proof valves.

In some embodiments, a first gap is provided between an outer side of the restraint assembly and an inner side of the box assembly, the outer side of the restraint assembly and the inner side of the box assembly face each other along a height direction of the battery pack, and the first gap forms the first exhaust passage.

In some embodiments, the battery module includes a plurality of battery units, a first surface of each of the plurality of battery units is opposite to a top side or a bottom side of the restraint assembly, the first surface is the largest side of each of the plurality of battery units, and a second surface of each of the plurality of battery units is provided with a first explosion-proof valve, the second surface is perpendicular to the first surface; wherein the communication hole is disposed on the top side or the bottom side of the restraint assembly.

In some embodiments, the second surface of each of the plurality of battery units is disposed toward a side wall of the restraint assembly, and there is a second gap between the second surface and an inner surface of a side wall of the restraint assembly on the corresponding side, the second gap forms a second exhaust passage, and the communication hole is disposed on the restraint assembly at a position corresponding to the second gap, and communicates the second exhaust passage with the first exhaust passage.

In some embodiments, the battery pack further including a fireproof member, the fireproof member including:.

In some embodiments, the box assembly includes: a box and a cover which are snap-fit with each other in a height direction of the battery pack, and the box is internally provided with a plurality of fixed beams;.

In some embodiments, the first restraint member includes: a first limiting portion and two first mounting portions, the first limiting portion covers a portion of the battery module close to the box, and the two first mounting portions are respectively connected to both sides of the first limiting portion along an arrangement direction of the plurality of fixed beams;.

In some embodiments, the first limiting portion entirely protrudes relative to the two first mounting portions toward a bottom side of the box; and/or
the second limiting portion entirely protrudes relative to the two second mounting portions toward a top side of the cover.

In some embodiments, the battery pack further including:
a second explosion-proof valve disposed on the box assembly and communicating with the first exhaust passage.

According to another aspect of the embodiments of the present disclosure, a transportation vehicle is provided. The transportation vehicle includes the battery pack according to the above-described embodiments, which is configured to supply electrical energy.

In the battery pack according to the embodiments of the present disclosure, a restraint assembly is provided within a box assembly, and an accommodating cavity for accommodating a battery module is provided inside the restraint assembly. Since the battery module is provided within the restraint assembly, when the battery module suffers from thermal runaway, fluids such as sparks and hot air ejected from the accommodating cavity into the first exhaust passage directly through the communication hole, to facilitate the discharge of fluid, and it is possible to prevent the fluid from entering other restraint assemblies to affect normal battery modules, thereby improving the operational safety of the battery pack.

The drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of the present application. The illustrative embodiments of the present disclosure as well as the descriptions thereof, which are used for explaining the present disclosure, do not constitute improper definitions on the present disclosure. In the accompanying drawings:.

The present disclosure will be explained in detail below. In the following paragraphs, different aspects of the embodiments will be defined in more detail.

The terms "first" and "second" recited in the present disclosure are merely for ease of description, to distinguish different constituent parts having the same name, rather than indicating a sequential or primary-secondary relationship.

In addition, when an element is referred to as being "on" another element, it may be directly on another element, or one element or may be indirectly on another element with one or more intermediate elements therebetween. In addition, when an element is referred to as being "connected to" another element, the element may be directly connected to another element, or may be indirectly connected to another element with one or more intermediate elements therebetween. In the following, the same reference numerals present the same elements.

In the present disclosure, "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

In order to clearly describe each orientation in the following embodiments, for example, the coordinate system in <FIG> defines each direction of the battery pack, wherein an x direction represents a length direction of the battery pack (hereinafter referred to as a length direction for short); a y direction represents a width direction of the battery pack (hereinafter referred to as a width direction for short); a z direction which is perpendicular to a plane formed by the x and y directions, represents a height direction of the battery pack (hereinafter referred to as a height direction for short). Based on such orientation definition, "up", "down", "top", and "bottom" are all relative to a height direction.

The embodiments of the present disclosure provide a battery pack and a vehicle, which can improve the operation safety of the battery pack.

<FIG> are schematic structural views of a battery pack according to some embodiments of the present disclosure. The battery pack may be used in a transportation vehicle to supply electrical energy for operation of the device. For example, the transportation includes a vehicle or a ship. The battery pack may include a box assembly <NUM>, a restraint assembly <NUM> and a battery module <NUM>.

The restraint assembly <NUM> is disposed within the box assembly <NUM>, and an accommodating cavity <NUM> is formed inside the restraint assembly <NUM>. A first exhaust passage <NUM> is provided between the restraint assembly <NUM> and the box assembly <NUM>. The restraint assembly <NUM> is provided with a communication hole <NUM>. The communication hole <NUM> communicates the accommodating cavity <NUM> with the first exhaust passage <NUM>.

The battery module <NUM> is disposed within the accommodating cavity <NUM>. A plurality of battery modules <NUM> may be provided in the battery pack, and a plurality of restraint assemblies <NUM> may be provided accordingly. The battery modules <NUM> are respectively disposed within the accommodating cavities <NUM> of the restraint assemblies <NUM>. Each of the accommodation cavities <NUM> is provided with one battery module <NUM>. For example, the size of the accommodating cavity <NUM> is adapted to the overall external dimensions of the corresponding battery module <NUM>. The battery module <NUM> includes a plurality of battery units <NUM>, for example, the battery module <NUM> may be provided with one layer or stacked with a plurality of layers of battery units <NUM> along the height direction.

In this embodiment, the battery module <NUM> is disposed within the restraint assembly <NUM>, and the restraint assembly <NUM> encloses the battery module <NUM> in an area beyond the communication hole <NUM>. Each of the restraint assemblies <NUM> is independent of each other. When the battery module <NUM> suffers from thermal runaway, fluid may be ejected, for example, the fluid includes hot air and sparks and mist-like electrolyte mingled in the hot air. The fluid can only enter from the accommodating cavity <NUM> into the first exhaust passage <NUM> directly through the communication hole <NUM>, to facilitate the discharge of fluid, and it is possible to prevent the fluid from entering other restraint assemblies <NUM> to affect normal battery modules <NUM>, thereby improving the operational safety of the battery pack.

As shown in <FIG>, a plurality of fixed beams <NUM> are provided inside the box assembly <NUM>, and the fixed beams <NUM> may be disposed at intervals inside the box assembly <NUM> along the length direction (x direction) or the width direction (y direction). The restraint assembly <NUM> is fixed to two adjacent fixed beams <NUM>, and a first exhaust passage <NUM> is formed among the restraint assembly <NUM>, the box assembly <NUM> and the two adjacent fixed beams <NUM>. Therefore, the first exhaust passage <NUM> may be directly formed by the box assembly <NUM>, the restraint assembly <NUM>, and the fixed beam <NUM>, without adding additional structural members, which may simplify the structure and reduce the machining difficulty.

The box assembly <NUM> may include: a box <NUM> and a cover <NUM> which are snap-fit to each other in the height direction. The cover <NUM> encloses the opening end of the box <NUM>. Here, the word "enclose" refers to a sealed connection between the box <NUM> and the cover <NUM>, which may prevent external liquid and water vapor from entering the battery pack, and improve the safety performance of the battery pack.

The box <NUM> is located at the bottom of the cover <NUM>, and the plurality of fixed beams <NUM> may be fixed to the box <NUM>. For example, the fixed beam <NUM> may be fixed on the inner bottom surface or the sidewall of the box <NUM>. For the specific structure of the fixed beam <NUM>, a solid or hollow structure may be used. For example, a lightening slot <NUM> is provided inside the fixed beam <NUM>. The cross section of the fixed beam <NUM> may be rectangular, trapezoidal or C-shaped and the like, and the upper surface thereof may be provided as a flat surface, so as to fix the restraint assembly <NUM> on the upper surface of the fixed beam <NUM>. Alternatively, the restraint assembly <NUM> may also be fixed on the side of the fixed beam <NUM>.

As shown in <FIG> and <FIG>, each of the plurality of battery units <NUM> is provided with a first explosion-proof valve <NUM>, which is configured to open when a difference between the internal and external pressures of the battery unit <NUM> exceeds a first preset pressure value, so as to discharge the gas in <NUM> within the battery unit <NUM>. As shown in <FIG>, a second exhaust passage <NUM> is formed between the restraint assembly <NUM> and the battery module <NUM> inside, and each of the first explosion-proof valves <NUM> faces the second exhaust passage <NUM>, and the communication hole <NUM> communicates the second exhaust passage <NUM> with the first exhaust passage <NUM>.

In some embodiments, the volume of the second exhaust passage <NUM> is smaller than that of the first exhaust passage <NUM>, so that the pressure within the second exhaust passage <NUM> is greater than the pressure within the first exhaust passage <NUM>, which can allow the fluid released by the battery unit <NUM> to smoothly enter the first exhaust passage <NUM> from the second exhaust passage <NUM> through the first explosion-proof valve <NUM> so as to ensure that the fluid is rapidly guided to the outside of the battery pack according to a predetermined discharge path, thereby lowering the risk of thermal runway in other battery modules <NUM>, and further improving the operational safety of the battery pack.

As shown in <FIG> and <FIG>, the battery pack of the present disclosure may further include a fireproof member <NUM>, the fireproof member <NUM> is provided between the restraint assembly <NUM> and the battery module <NUM> and covering the first explosion proof valve <NUM> of each of the plurality of battery units <NUM>, and a second exhaust passage <NUM> is formed between the fireproof member <NUM> and the battery module <NUM>. For example, the fireproof member <NUM> may be made from a fireproof material, such as a mica board or the like, or a fireproof coating may be externally applied to the metal structure.

By providing the fireproof member <NUM>, when the battery unit <NUM> suffering from thermal runaway releases a fluid such as hot air and sparks through the first explosion-proof valve <NUM>, the fluid may be prevented from directly impacting the restraint assembly <NUM>. Since the restraint assembly <NUM> is generally formed by bending a sheet, when the fluid has a high temperature or a fast speed, it is likely to cause the restraint assembly <NUM> to deform or break through the restraint assembly <NUM>, so that the fluid safely enters the first exhaust passage <NUM> through the communication hole <NUM>, thereby improving the safety and the operational reliability of the battery pack structure,
The specific structure that may be used by the above-described members will be specifically described below with the battery pack shown in <FIG> as an example.

The battery units <NUM> in the battery module <NUM> forms at least one battery unit assembly 2A. The electrical connection manners among each of the battery unit assemblies 2A is provided to be in series, parallel, or both in series and parallel. An end plate <NUM> is provided at an end of the fixed beam <NUM> along the extending direction thereof.

Within the horizontal plane, two adjacent battery unit assemblies 2A may be mounted in such a manner that the electrode terminals face each other, and it is necessary to leave a safe distance between the electrode terminals of adjacent battery unit assemblies 2A. Alternatively, two adjacent battery unit assemblies 2A may be mounted in such a manner that the electrode terminals face away from each other, which may save the installation space, and a cooling plate may be provided between two adjacent battery unit assemblies 2A to achieve cooling, so that two adjacent battery unit assemblies 2A are cooled at the same time by a cooling plate.

The battery unit assembly 2A includes a plurality of battery units <NUM> disposed side by side along the length direction or width direction of the battery pack. As shown in <FIG>, each of the plurality of battery units <NUM> includes a first surface S1, a second surface S2, and a third surface S3, wherein the first surface S1 is the largest side surface of each of the plurality of battery units <NUM>; the second surface S2 is perpendicular to the first surface S1, and provided with a first explosion-proof valve <NUM>, a first electrode terminal <NUM>, and a second electrode terminal <NUM>; the third surface S3 and the second surface S2 are oppositely disposed.

The first surface S1 of each of the battery units <NUM> is opposite to the top side or the bottom side of the restraint assembly <NUM>. Such arrangement manner is also referred to as flat arrangement, which may improve the space utilization rate inside the battery pack. Since the height of the battery unit assembly 2A is relatively short in the height direction, the overall height of the battery pack may be reduced in a flat arrangement manner, which is more suitable for vehicles with a relatively short installation space for the battery pack. Moreover, for a flat arrangement manner of each of the battery units <NUM>, the positive and negative pole pieces of the electrode assembly <NUM> are stacked along the height direction of the battery pack, and the expansion force of the battery unit <NUM> may be transferred along the height direction, so that it is possible to suppress the expansion force produced by the electrode assembly <NUM> by way of the restraint assembly <NUM>. Even if the restraint assembly <NUM> is deformed under the effect of the expansion force, the first exhaust passage <NUM> may also provide an expansion space for the restraint assembly <NUM>.

Alternatively, the second surface S2 of each of the plurality of battery units <NUM> may also be opposite to the top side of the restraint assembly <NUM>.

In <FIG>, the battery units <NUM> in the same battery unit assembly 2A are disposed side by side along the length direction (x direction). Two rows of battery unit assemblies 2A are disposed along the width direction (x direction). In practical applications, three rows or more may also be provided. In the height direction (z direction), one or more layers of battery unit assemblies 2A may also be provided, and each layer of battery unit assemblies 2A may be stacked along the height direction.

In order to avoid heat transfer from the battery units <NUM> suffering from thermal runaway to adjacent battery units <NUM>, the battery pack may include a thermal insulation layer <NUM> provided between two adjacent battery units <NUM>. For example, a thermal insulation layer <NUM> is provided between two adjacent battery units <NUM> in the height direction, or a thermal insulation layer <NUM> is provided between adjacent battery units <NUM> within a horizontal plane. The thermal insulation layer <NUM> may be a thermal insulation glue, which may fix the respective battery units <NUM> to each other while producing a thermal insulation effect.

On such basis, as shown in <FIG>, the restraint assembly <NUM> is provided with a plurality of communication holes <NUM>, each of which is provided in one-to-one correspondence with each of the first explosion-proof valves <NUM> in one layer. For the embodiment in which the second surfaces S2 of the battery units <NUM> in two groups of battery unit assemblies 2A are disposed towards a direction facing away from each other, a column of communication holes <NUM> are provided at areas on both sides of the restraint assembly <NUM> along the arrangement direction of the plurality of fixed beams <NUM>. Each column of communication holes <NUM> includes a plurality of communication holes <NUM> disposed at intervals along the extending direction of the fixed beam <NUM>, and are in one-to-one correspondence with the first explosion-proof valves <NUM> of the single-layer battery units <NUM> in the battery unit assembly 2A respectively. For example, the communication hole <NUM> may be circular, oval, polygonal, or other irregular shapes.

With such structure, when any of the battery units <NUM> in the battery module <NUM> suffers from thermal runaway, it is possible to allow the released fluid to enter the first exhaust passage <NUM> through the communication hole <NUM> at the corresponding position in the shortest path, and to discharge through a plurality of communication holes <NUM> at the same time, which may lessen the fluid discharge time and reduce the risk of thermal runaway in other battery units <NUM> of the battery module <NUM> or in other battery modules <NUM>.

As shown in <FIG>, there is a first gap L1 between the outer side of the restraint assembly <NUM> and the inner side of the box assembly <NUM>. The outer side of the restraint assembly <NUM> and the inner side of the box assembly <NUM> face each other along the height direction. The first gap L1 forms the first exhaust passage <NUM>.

With such structure, it is possible to allow the space between the restraint assembly <NUM> and the box assembly <NUM> to serve as the first exhaust passage <NUM> with a larger area, when the battery module <NUM> suffers from thermal runaway, the air pressure within the first exhaust passage <NUM> is lower, the fluid released during thermal runaway may be discharged more smoothly, thereby preventing more fluid accumulated within the accommodating cavity <NUM>, and the air pressure and temperature within the accommodating cavity <NUM> may be rapidly reduced, thereby improving the safety of the battery pack.

As shown in <FIG> and <FIG>, the communication hole <NUM> is provided on the top side or bottom side of the restraint assembly <NUM>, and located on the same side as the first exhaust passage <NUM> in the height direction. In this way, the fluid released when the battery module <NUM> suffers from thermal runaway may enter the first exhaust passage <NUM> directly through the communication hole <NUM> from the second exhaust passage <NUM> without passing through an additional guide path, which may improve the fluid discharge efficiency. Moreover, after the fluid directly enters the first exhaust passage <NUM>, since the first exhaust passage <NUM> has a large volume, the pressure of the fluid may be instantaneously reduced, and the temperature may also be reduced accordingly, which may prevent a continuous increase in the pressure and temperature within the battery pack and improve the operational safety.

In some embodiments, the communication hole <NUM> is provided in the bottom side of the restraint assembly <NUM>, and a first gap L1 between the outer side at the bottom of the restraint assembly <NUM> and the inner side at the bottom of the box assembly <NUM> forms a first exhaust passage <NUM>. When the battery pack is installed in the vehicle, when the battery module <NUM> suffers from thermal runaway, the airflow having a high temperature is concentrated and discharged in the bottom area of the battery pack, thereby preventing the impact on personnel and articles within the vehicle body and improving the safety within the vehicle body.

As shown in <FIG>, the second surface S2 of each of the plurality of battery units <NUM> is disposed toward the side wall of the restraint assembly <NUM>, and a second gap L2 is provided between the second surface S2 of the restraint assembly <NUM> and an inner surface of a side wall of the restraint assembly <NUM> on the corresponding side. The second gap L2 forms a second exhaust passage <NUM>. The communication hole <NUM> is provided on the restraint assembly <NUM> at a position corresponding to the second gap L2, and communicates the second exhaust passage <NUM> with the first exhaust passage <NUM>.

By providing the second gap L2, a space may be reserved for the first electrode terminal <NUM>, the second electrode terminal <NUM>, and a busbar connecting the first electrode terminal <NUM> and the second electrode terminal <NUM>, and also for between the first explosion-proof valve <NUM> and the side wall of the restraint member <NUM>. During thermal runaway in the battery unit <NUM>, the fluid released through the first explosion-proof valve <NUM> diffuses into the second exhaust passage <NUM>, and flows rapidly into the first exhaust passage <NUM> through a plurality of communication holes <NUM>. Moreover, since the volume of the second exhaust passage <NUM> is smaller than that of the first exhaust passage <NUM>, the pressure within the second exhaust passage <NUM> is higher than that within the first exhaust passage <NUM>, so that the fluid may be smoothly discharged according to a preset path.

As shown in <FIG>, the extending direction of the fireproof member <NUM> is consistent with the same of the fixed beam <NUM>. The fireproof member <NUM> includes: a first portion <NUM> and two second portions <NUM>. The first portion <NUM> abuts against the inner surface of the side wall of the restraint assembly <NUM>, and forms a second gap L2 between the first portion <NUM> and the second surface S2 of each of the battery units <NUM> on the corresponding side. The two second portions <NUM> are respectively connected to both ends of the first portion <NUM> along the height direction and extending toward the second surface S2 until abutting against the second surface S2. The second portion <NUM> is provided with an avoidance hole <NUM> at a position corresponding to the communication hole <NUM>. Wherein, the first explosion-proof valve <NUM> is located between the two second portions <NUM>. Further, the two second portions <NUM> may abut against the top side and the bottom side of the restraint assembly <NUM> respectively.

As shown in <FIG>, the avoidance hole <NUM> may be provided on one of the two second portions <NUM> at the bottom. As shown in <FIG>, the communication hole <NUM> is a rectangular slot. Accordingly, the avoidance hole <NUM> may be a rectangular hole which is open on a side of the second portion <NUM> away from the side of the first portion <NUM>. As a result, a plurality of avoidance holes <NUM> are provided at intervals in the second portion <NUM> along the extending direction of the fixed beam <NUM>. Such structure is easily machined and can enhance the structural stability of the fireproof member <NUM> whilst not affecting the discharge of fluid.

The fireproof member <NUM> integrally forms a space surrounding the first explosion-proof valves <NUM>, and forms a second exhaust passage <NUM> between the fireproof member <NUM> and the second surface S2 of each of the battery units <NUM>, which may prevent fluid from directly impacting the restraint assembly <NUM> when the battery unit <NUM> suffering from thermal runaway releases fluids such as hot air and sparks through the first explosion-proof valve <NUM>. The fireproof member <NUM> abuts against the restraint assembly <NUM>, so that the fireproof member <NUM> may be reliably positioned to prevent shaking.

As shown in <FIG>, the restraint assembly <NUM> includes: a first restraint member <NUM> and a second restraint member <NUM>. The first restraint member <NUM> and the second restraint member <NUM> are snap-fit with each other in the height direction to form an accommodating cavity <NUM>. The first restraint member <NUM> is configured to limit the freedom of movement of the battery module <NUM> toward the box <NUM> along the height direction, and the second constraint member <NUM> is configured to limit the freedom of movement of the battery module <NUM> toward the cover <NUM> along the height direction. Wherein, the communication hole <NUM> is disposed on the first restraint member <NUM>, and there is a first gap L1 between the box <NUM> and the first restraint member <NUM> along the height direction. The first gap L1 forms the first exhaust passage <NUM>.

In this embodiment, the communication hole <NUM> is disposed in the first restraint member <NUM> at the bottom side, and the first gap L1 between the first restraint member <NUM> and the box <NUM> forms the first exhaust passage <NUM>. When the battery pack is installed on the vehicle, upon thermal runaway in the battery module <NUM>, the airflow having a high temperature is concentrated and discharged in the bottom area of the battery pack, thereby preventing the impact on personnel and articles within the vehicle body and improving the safety within the vehicle body.

Specifically, as shown in <FIG>, the first restraint member <NUM> includes a first limiting portion <NUM> and two first mounting portions <NUM>. The first limiting portion <NUM> covers a portion of the battery module <NUM> close to the box <NUM>. The two first mounting portions <NUM> are respectively connected to both sides of the first limiting portion <NUM> along the arrangement direction of the plurality of fixed beams <NUM>. The first limiting portion <NUM> entirely protrudes relative to the two first mounting portion <NUM> toward a bottom side of the box <NUM>.

The second restraint member <NUM> includes: a second limiting portion <NUM> and two second mounting portions <NUM>. The second limiting portion <NUM> covers a portion of the battery module <NUM> close to the cover <NUM>. The two second mounting portions <NUM> are respectively connected to both sides of the second limiting portion <NUM> along the arrangement direction of the plurality of fixed beams <NUM>.

Wherein, the accommodating cavity <NUM> is formed between the first limiting portion <NUM> and the second limiting portion <NUM>. One of the two second mounting portions <NUM> and one of the two first mounting portions <NUM> located on the same side of the battery module <NUM> are stacked in the height direction, and fixed to the same one of the plurality of fixed beams <NUM> by a group of fasteners <NUM>. The second limiting portion <NUM> entirely protrudes relative to the two second mounting portion <NUM> toward a top side of the cover <NUM>.

As shown in <FIG>, the first mounting portion <NUM> is provided with a plurality of first mounting holes <NUM> at intervals along the extending direction of the fixed beam <NUM>, and the second mounting portion <NUM> is provided with a plurality of second mounting holes <NUM> at intervals along the extending direction of the fixed beam <NUM>. The fixed beam <NUM> is provided with a plurality of third mounting holes <NUM> along the extending direction thereof. The fastener <NUM> sequentially passes through the second mounting hole <NUM>, the first mounting hole <NUM>, and the third mounting hole <NUM> from the top, so as to fix the first restraint member <NUM> and the second restraint member <NUM> to the fixed beam <NUM>.

As shown in <FIG>, the battery pack further includes: a second explosion-proof valve <NUM> provided on the box assembly <NUM> and communicating with the first exhaust passage <NUM>, which is configured to open to discharge an internal fluid when a difference between the internal and external pressures of the box assembly <NUM> exceeds a second preset pressure value. Specifically, the second explosion-proof valve <NUM> may be provided on a side of the cover <NUM> located at one end of the fixed beam <NUM>.

Still referring to <FIG>, in order to fix the cover <NUM> with the box <NUM>, a first flanging <NUM> is provided around the opening end of the box <NUM>, and a second flanging <NUM> is provided around the cover <NUM>. The first flanging <NUM> and the second flanging <NUM> may be fixed therebetween in a manner of adhesive or a fastener.

The battery packs of the above-described embodiments respectively cover different battery modules <NUM> through a plurality of second restraint members <NUM>, and are fixed to the corresponding fixed beams <NUM> (that is, the fixing points between the second restraint member <NUM> and the box <NUM> are increased), so that the span between the fixing points is reduced, which may improve the deformation resistance of the second restraint member <NUM>. When the battery unit <NUM> expands, the second restraint member <NUM> is not easily deformed, which may further provide a stable pressing force to the battery module <NUM> so as to prevent an increased size of the battery pack in the height direction, and it is also not likely to extrude the cover <NUM> due to the deformation of the restraint member <NUM>, which may improve the service life of the battery pack.

As shown in <FIG>, there is a third gap L3 between the inner surface of the top wall of the box assembly <NUM> and the outer surface of the top wall of the restraint assembly <NUM>, that is, there is a third gap L3 between the inner surface of the cover <NUM> and the outer surface of the second restraint member <NUM>. By providing the first gap L1 and the third gap L3, even if the restraint assembly <NUM> is deformed due to the expansion of the battery unit <NUM>, it is also possible to prevent deformation of the box assembly <NUM>.

The fluid discharge manner of the battery pack of the present disclosure upon thermal runaway will be described below in conjunction with <FIG>. As shown in <FIG>, when the battery module <NUM> has a battery unit <NUM> suffering from thermal runaway, fluids such as hot air and sparks may be released by the first explosion-proof valve <NUM> inside the battery unit <NUM> into the second exhaust passage <NUM> to circulate, and enter the first exhaust passage <NUM> through the plurality of communication holes <NUM> in the first limiting portion <NUM> during the flow. Referring to <FIG>, the fluid flows within the first exhaust passage <NUM> and flows upwards in a space formed between the restraint assembly <NUM> and the side of the box assembly <NUM>, such as to be discharged out of the battery pack through the second explosion-proof valve <NUM>. Such battery pack may prevent sparks from splashing into other battery modules <NUM> with normal performance, and at the same time may prevent hot air from baking other battery modules <NUM> and reduce the risk of thermal runaway in multiple battery modules <NUM> after thermal diffusion.

The specific structure of the battery unit <NUM> in each of the above-described embodiments will be described below in conjunction with <FIG>.

As shown in the exploded schematic view in <FIG>, each of the battery units <NUM> includes: a housing <NUM> and an electrode assembly <NUM> disposed within the housing <NUM>. The housing <NUM> may have a hexahedron shape or other shapes and include an opening. The electrode assembly <NUM> is accommodated within the housing <NUM>. The opening of the housing <NUM> is covered with a cover plate assembly <NUM>. The cover plate assembly <NUM> includes a cover plate <NUM> and two electrode terminals provided on the cover plate. The two electrode terminals are a first electrode terminal <NUM> and a second electrode terminal <NUM> respectively. The first electrode terminal <NUM> may be a positive electrode terminal, and the second electrode terminal <NUM> may be a negative electrode terminal. In other embodiments, the first electrode terminal <NUM> may be a negative electrode terminal, and the second electrode terminal <NUM> may be a positive electrode terminal. An adapter piece <NUM> is provided between the cover plate assembly <NUM> and the electrode assembly <NUM>. The tabs of the electrode assembly <NUM> are electrically connected to the electrode terminals on the cover plate <NUM> through the adapter piece <NUM>. In the present embodiment, there are two adapter pieces <NUM>, that is, a positive adapter piece and a negative adapter piece respectively.

As shown in <FIG>, the housing <NUM> is internally provided with two electrode assemblies <NUM>, which are stacked along the height direction (z direction) of the battery units <NUM>, wherein the height direction of the battery units <NUM> conforms to that of the battery pack. Of course, in other embodiments, the housing <NUM> may be also be internally provided with one electrode assembly <NUM>, or three or more electrode assemblies <NUM> The plurality of electrode assemblies <NUM> are stacked along the height direction (z direction) of the battery units <NUM>.

As shown in <FIG> and <FIG>, the electrode assembly <NUM> includes a first pole piece <NUM>, a second pole piece <NUM>, and a diaphragm <NUM> disposed between the first pole piece <NUM> and the second pole piece <NUM>. The first pole piece <NUM> may be a positive pole piece, and the second pole piece <NUM> may be a negative pole piece. In other embodiments, the first pole piece <NUM> may also be a negative pole piece, and the second pole piece <NUM> may be a positive pole piece. Wherein, the diaphragm <NUM> is an insulator between the first pole piece <NUM> and the second pole piece <NUM>. The active substance of the positive pole piece may be coated on the coating area of the positive pole piece, and the active substance of the negative pole piece may be coated on the coating area of the negative pole piece. The portion extending from the coating area of the positive pole piece serves as the positive electrode tab; the portion extending from the coating area of the negative pole piece serves as the negative electrode tab. The positive electrode tab is connected to the positive electrode terminal on the cover plate assembly <NUM> through the positive electrode adapter plate. Similarly, the negative electrode tab is connected to the negative electrode terminal on the cover plate assembly <NUM> through the negative electrode adapter plate.

As shown in <FIG>, the electrode assembly <NUM> has a wound structure. Wherein, the first pole piece <NUM>, the diaphragm <NUM>, and the second pole piece <NUM> are all strip-like structures. The first pole piece <NUM>, the diaphragm <NUM>, and the second pole piece <NUM> are sequentially stacked and wound more than two turns to form the electrode assembly <NUM>, and the electrode assembly <NUM> is flat-shaped. When the electrode assembly <NUM> is manufactured, the electrode assembly <NUM> may be directly wound into a flat shape, or may also be wound into a hollow cylindrical structure first, and then flattened into a flat shape after being wound. <FIG> is a schematic view of an outer contour of the electrode assembly <NUM>. The outer surface of the electrode assembly <NUM> includes two flat surfaces <NUM>, which are oppositely disposed along the height direction (z direction) of the battery unit <NUM>. Wherein, the electrode assembly <NUM> is substantially a hexahedron structure, and the flat surface <NUM> is substantially parallel to the winding axis, and is the outer surface with a maximum area. The flat surface <NUM> may be a relatively flat surface, and is not required to be a pure plane.

As shown in <FIG>, the electrode assembly <NUM> has a laminated structure, that is, the electrode assembly <NUM> includes a plurality of first pole pieces <NUM> and a plurality of second pole pieces <NUM>, and diaphragms <NUM> are disposed between the first pole pieces <NUM> and the second pole pieces <NUM>. The first pole pieces <NUM> and the second pole pieces <NUM> are stacked along the height direction (z direction) of the battery unit <NUM>.

The electrode assembly <NUM> may inevitably expand along the thickness direction of the pole pieces during the charging and discharging processes. The expansion amounts of the respective pole pieces are superimposed, and the accumulated expansion amount in the height direction is greater than that in other directions. In the embodiments of the present disclosure, the direction of the battery unit <NUM> at a maximum expansion may be restrained by increasing the fixing points between the restraint assembly <NUM> and the box <NUM>, thereby preventing deformation of the battery pack, and raising the service life of the battery pack.

Claim 1:
A battery pack, comprising:
a box assembly (<NUM>), internally provided with a plurality of fixed beams (<NUM>) at intervals;
a plurality of restraint assemblies (<NUM>), disposed within the box assembly (<NUM>), wherein each of the plurality of restraint assemblies (<NUM>) is fixed to two adjacent fixed beams (<NUM>) and internally provided with an accommodating cavity (<NUM>), a first exhaust passage (<NUM>) is provided between the restraint assembly (<NUM>) and the box assembly (<NUM>), and the restraint assembly (<NUM>) is provided with a communication hole (<NUM>) which communicates the accommodating cavity (<NUM>) with the first exhaust passage (<NUM>), and the first exhaust passage (<NUM>) is formed among the restraint assembly (<NUM>), the box assembly (<NUM>) and the two adjacent fixed beams (<NUM>); and
a plurality of battery modules (<NUM>), respectively disposed within the accommodating cavities (<NUM>) of the plurality of restraint assemblies (<NUM>).