BOX ASSEMBLY, BATTERY MODULE, BATTERY, AND ELECTRICAL DEVICE

This application relates to the field of battery technology, and in particular, to a box assembly, a battery module, a battery, and an electrical device. The box assembly may include at least a partition piece and two end plates. In the box assembly disclosed herein, a stress relief piece may be disposed at two ends of a main body of the partition piece. The main body may be connected to the end plate by use of the stress relief piece. A corner may be formed between the stress relief piece and the main body. In this way, when the battery module is subjected to stress, at least a part of the stress can be relieved through the corner formed between the stress relief piece and the main body.

TECHNICAL FIELD

This application relates to the field of battery technology, and in particular, to a box assembly, a battery module, a battery, and an electrical device.

BACKGROUND

During the use of a battery, a battery module is subjected to stress such as a cell expansion force and an external force. An excessive stress impairs structural reliability of the battery module.

SUMMARY

In view of the above problems, this application provides a box assembly, a battery module, a battery, and an electrical device to alleviate the structural reliability problem of the battery module caused by stress encountered by the battery in use.

According to a first aspect, this application provides a box assembly. The box assembly is configured to fix a plurality of battery cells. The box assembly includes: two end plates, arranged apart along a preset direction and opposite to each other; and a partition piece. The partition piece includes a main body and a stress relief piece. The main body is disposed between the two end plates along the preset direction. The stress relief piece is disposed at two ends of the main body in the preset direction and forms a corner between the stress relief piece and the main body. Each stress relief piece is fixedly connected to a corresponding end plate.

In the technical solution in an embodiment of this application, a stress relief piece is disposed at the two ends of the main body of the partition piece, the main body is connected to the end plate by use of the stress relief piece, and the corner is formed between the stress relief piece and the main body. In this way, when the battery module is subjected to stress, at least a part of the stress can be relieved through the corner formed between the stress relief piece and the main body, thereby reducing stress concentration at the stress relief piece and a corresponding position on the end plate, and in turn, improving reliability of connection between the partition piece and the end plate, and effectively improving structural reliability of the battery module.

In some embodiments, the stress relief piece is configured to be formed in one piece by bending a corresponding end of the main body. With the stress relief piece being formed in one piece by bending a corresponding end of the main body, it is convenient to form a corner between the stress relief piece and the main body.

In some embodiments, a bending angle of the stress relief piece is α, satisfying: 87°≤α≤93°. With the bending angle falling within the above range, not only the desired corner can be formed, but also the stress relief piece can be fixedly connected to the corresponding end plate conveniently.

In some embodiments, an opening is created on each end plate. The stress relief piece located at each of two opposite ends of the main body protrudes out of the corresponding end plate through the opening. Such arrangement causes the stress relief piece to be formed outside the end plate, thereby making it more convenient to connect the stress relief piece and the corresponding end plate together.

In some embodiments, grooves recessed toward each other are created on a side of one of the two end plates and a side of the other of the two end plates respectively, the two sides being oriented away from each other. The opening is created on bottom walls of the grooves. In this way, because the opening is created on the bottom wall of the groove, the stress relief piece can be accommodated in the groove after protruding out of the corresponding end plate through the opening, thereby further protecting the connection structure between the stress relief piece and the corresponding end plate.

In some embodiments, the stress relief piece is fixedly connected to the corresponding end plate by welding. The welding process can fixedly connect the stress relief piece and the corresponding end plate together.

In some embodiments, the welding process includes at least one of laser filler wire welding or cold metal transfer welding. In the box assembly in such embodiments of this application, the welding process for fixedly connecting the stress relief piece and the corresponding end plate together is flexible, and any welding process is appropriate as long as the welding makes it convenient to fixedly connect the stress relief piece and the corresponding end plate together.

In some embodiments, the stress relief piece is fixedly connected to the corresponding end plate by riveting. The riveting process can fixedly connect the stress relief piece and the corresponding end plate together.

In some embodiments, the box assembly further includes two side plates. The two side plates are arranged apart along a direction perpendicular to the preset direction and are opposite to each other. Two ends of each of the side plates along the direction perpendicular to the preset direction are fixedly connected to corresponding end plates respectively. In this way, by disposing the two side plates, the box assembly closes in to form a mounting cavity configured to fix a plurality of battery cells.

In some embodiments, the side plate is fixedly connected to the corresponding end plates by welding or riveting. In the box assembly in such embodiments of this application, the fastening manner for fixedly connecting the side plate and the corresponding end plates together is flexible, and any fastening manner is appropriate as long as the manner makes it convenient to fasten the side plate and the corresponding end plates together.

According to a second aspect, this application provides a battery module. The battery module includes a plurality of battery cells and the box assembly according to the foregoing embodiment. A mounting cavity is formed in the box assembly, and the mounting cavity is configured to fix the plurality of battery cells. In this way, due to the use of the box assembly disclosed in the foregoing embodiment, when the battery module is subjected to stress, at least a part of the stress can be relieved through the corner formed between the stress relief piece and the main body, thereby reducing stress concentration at the stress relief piece and a corresponding position on the end plate, and in turn, improving reliability of connection between the partition piece and the end plate, and effectively improving structural reliability of the battery module.

In some embodiments, the plurality of battery cells are arranged in parallel. At least one partition piece is disposed between two adjacent rows of battery cells of at least one pair of adjacent rows of battery cells. In the box assembly in such embodiments of this application, the arrangement of the partition piece between the battery cells is flexible, and any arrangement is appropriate as long as a partition piece is disposed between two adjacent rows of battery cells of at least one pair of adjacent rows of battery cells.

According to a third aspect, this application provides a battery. The battery includes the battery module according to the foregoing embodiment. In this way, due to the use of the battery module disclosed in the foregoing embodiment, the reliability of the battery module is high, and therefore, the reliability of the battery is improved.

According to a fourth aspect, this application provides an electrical device. The electrical device includes the battery disclosed in the foregoing embodiment. The battery is configured to provide electrical energy. In this way, due to the use of the battery disclosed in the foregoing embodiment, the reliability of the battery is high, and therefore, the reliability of the electrical device is improved.

In an embodiment of this application, the structure of the box assembly is improved in view of the stress such as cell expansion force and external force to be encountered by the battery in use. A stress relief piece is disposed at two ends of the main body of the partition piece, and a corner is formed between the stress relief piece and the main body. The stress relief piece is connected to the corresponding end plate. In this way, when the battery module is subjected to the stress, at least a part of the stress can be relieved through the corner formed between the stress relief piece and the main body, thereby reducing stress concentration at the stress relief piece and a corresponding position on the end plate, and in turn, improving reliability of connection between the partition piece and the end plate, and effectively improving structural reliability of the battery module.

The foregoing description is merely an overview of the technical solutions of this application. Some specific embodiments of this application are described below illustratively to enable a clearer understanding of the technical solutions of this application, enable implementation of the technical solutions based on the subject-matter hereof, and make the foregoing and other objectives, features, and advantages of this application more evident and comprehensible.

LIST OF REFERENCE NUMERALS

DETAILED DESCRIPTION OF EMBODIMENTS

Some embodiments of the technical solutions of this application are described in detail below with reference to the drawings. The following embodiments are merely intended as examples to describe the technical solutions of this application more clearly, but not intended to limit the protection scope of this application.

Unless otherwise defined, all technical and scientific terms used herein bear the same meanings as what is normally understood by a person skilled in the technical field of this application. The terms used herein are merely intended to describe specific embodiments but not to limit this application. The terms “include” and “contain” and any variations thereof used in the specification, claims, and brief description of drawings of this application are intended as non-exclusive inclusion.

In the description of the embodiments of this application, the technical terms “first” and “second” are merely intended to distinguish between different items but not intended to indicate or imply relative importance or implicitly specify the number of the indicated technical features, specific order, or order of precedence. In the description of the embodiments of this application, unless otherwise expressly specified, “a plurality of” means two or more.

Reference to an “embodiment” herein means that a specific feature, structure or characteristic described with reference to this embodiment may be included in at least one embodiment of this application. Reference to this term in different places in the specification does not necessarily represent the same embodiment, nor does it represent an independent or alternative embodiment in a mutually exclusive relationship with other embodiments. A person skilled in the art explicitly and implicitly understands that the embodiments described herein may be combined with other embodiments.

In the description of embodiments of this application, the term “and/or” merely indicates a relationship between related items, and represents three possible relationships. For example, “A and/or B” may represent the following three circumstances: A alone, both A and B, and B alone. In addition, the character “/” herein generally indicates an “or” relationship between the item preceding the character and the item following the character.

In the description of embodiments of this application, the term “a plurality of” means two or more (including two). Similarly, “a plurality of groups” means two or more groups (including two groups), and “a plurality of pieces” means two or more pieces (including two pieces).

In the description of embodiments of this application, a direction or a positional relationship indicated by the terms such as “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “up”. “down”, “before”, “after”, “left”, “right”, “vertical”, “horizontal”. “top”, “bottom”, “in”, “out”, “clockwise”, “counterclockwise”, “axial”, “radial”, and “circumferential” is a direction or positional relationship based on the illustration in the drawings, and is merely intended for ease or brevity of description of embodiments of this application, but not intended to indicate or imply that the indicated device or component is necessarily located in the specified direction or constructed or operated in the specified direction. Therefore, such terms are not to be understood as a limitation on embodiments of this application.

In the description of the embodiments of this application, unless otherwise expressly specified and defined, the technical terms such as “mounting”, “concatenation”, “connection”, and “fixing” need to be understood in a broad sense, for example, understood as a fixed connection or a detachable connection or integrally formed; or understood as a mechanical connection or an electrical connection; understood as a direct connection, or an indirect connection implemented through an intermediary; or understood as internal communication between two components or interaction between two components. A person of ordinary skill in the art can understand the specific meanings of the terms in the embodiments of this application according to specific situations.

Currently, as can be seen from the market trend, the application of power batteries is increasingly extensive. Power batteries are not only used in energy storage power systems such as hydro, thermal, wind, and solar power stations, but also widely used in electric means of transport such as electric bicycles, electric motorcycles, and electric vehicles, and used in many other fields such as military equipment and aerospace. The market demand for power batteries keeps soaring with the increase of the application fields of the power batteries.

The applicant hereof has noticed that a battery module in the related art typically includes a plurality of battery cells. On the one hand, the battery cells are prone to expand after being charged repeatedly. With the expansion of the battery cells, a box assembly in which a plurality of battery cells are fixed is prone to fail under an expansion force. On the other hand, during the use of a battery module, the battery module is prone to receive stress such as an external force, thereby also impairing structural reliability of the box assembly. Therefore, under the stress such as cell expansion force and external force, the box assembly is prone to fail, thereby impairing the structural reliability of the battery module.

To relieve the stress encountered during use of the battery, the applicant hereof finds through research that the stress encountered by the battery module in use is transmitted to a junction in the box assembly or directly exerted on the junction in the box assembly. For example, under an expansion force, the stress is transmitted to the junction in the box assembly. For another example, under an external force, the stress may be directly exerted on the junction in the box assembly.

In view of the above considerations, in order to solve the reliability problem of the battery module structure caused by the stress encountered during the use of the battery, the applicant hereof has designed a box assembly after in-depth research. The box assembly includes at least one partition piece. The stress relief piece is disposed at the two ends of the main body of the partition piece, the main body is connected to the end plate by use of the stress relief piece, and the corner is formed between the stress relief piece and the main body. At least a part of the stress can be relieved by the corner before the stress reaches the junction between the partition piece and the end plate or when the stress is exerted on the junction.

In such a box assembly, due to the corner formed between the stress relief piece and the main body, the stress concentration can be reduced at the stress relief piece and a corresponding position on the end plate, thereby improving reliability of connection between the partition piece and the end plate, and effectively improving structural reliability of the battery module.

The box structure disclosed in an embodiment of this application is configured to fix, but not limited to use for fixing, a plurality of battery cells that are in the shape of a cylinder, a flat body, a cuboid, or another shape.

In this application, the battery cells may include types such as a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery. The type of the battery cell is not limited herein. The battery cell may be in various shapes such as a cylinder, flat body, or cuboid, without being limited in embodiments of this application. In terms of the packaging form, the battery cell is typically classed into three types: cylindrical battery cell, prismatic battery cell, and pouch-type battery cell. The type of the battery cell is not limited herein.

The battery mentioned in embodiments of this application means a unitary physical module that includes one or more battery cells to provide a higher voltage and a higher capacity. For example, the battery mentioned in this application may include a battery module, a battery pack, or the like. A battery typically includes a box configured to package one or more battery cells. The box prevents liquid or other foreign matters from affecting the charging or discharging of the battery cells.

The battery cell disclosed in embodiments of this application is applicable to, but not limited to use in, electrical devices such as a vehicle, watercraft, or aircraft. A power supply system of the electrical device may be formed by using the battery cell and battery disclosed in this application and the like, so as to relieve the stress encountered during use of the battery, and improve the reliability of the battery module structure.

An embodiment of this application provides an electrical device powered by a battery. The electrical device may be, but without being limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric power cart, an electric vehicle, a ship, a spacecraft, and the like. The electric toy may include stationary or mobile electric toys, such as a game console, an electric car toy, an electric ship toy, an electric airplane toy, and the like. The spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, and the like.

For ease of description in the following embodiments, a vehicle1is used as an example of the electrical device according to an embodiment of this application.

Referring toFIG.1,FIG.1is a schematic structural diagram of a vehicle1according to some embodiments of this application. The vehicle1may be an oil-fueled vehicle, a natural gas vehicle, or a new energy vehicle. The new energy vehicle may be a battery electric vehicle, a hybrid electric vehicle, a range-extended electric vehicle, or the like. A battery10is disposed inside the vehicle1. The battery10may be disposed at the bottom, front, or rear of the vehicle1. The battery10may be configured to supply power to the vehicle1. For example, the battery10may serve as an operating power supply of the vehicle1. The vehicle1may further include a controller20and a motor30. The controller20is configured to control the battery10to supply power to the motor30, for example, to meet electrical energy requirements in starting, navigating, or running the vehicle1.

In some embodiments of this application, the battery10serves not only as an operating power supply of the vehicle1, but may also serve as a drive power supply of the vehicle1to provide a driving power supply for the vehicle1in place of or partly in place of fuel oil or natural gas.

Referring toFIG.2,FIG.2is a schematic exploded view of a battery10according to some embodiments of this application. The battery10includes a box100and a battery module200. The battery module200is accommodated in the box100. The box100is configured to provide an accommodation space for the battery module200. The box100may assume various structures. In some embodiments, the box100may include a first part110and a second part120. The first part110and the second part120fit and cover each other. The first part110and the second part120together define an accommodation space configured to accommodate the battery module200. The second part120may be a hollow structure opened at one end. The first part110may be a plate-like structure. The first part110fits on an opening side of the second part120so that the first part110and the second part120together define the accommodation space. Alternatively, both the first part110and the second part120may be hollow structures opened at one side. The opening side of the first part110fits the opening side of the second part120. Definitely, the box100formed by the first part110and the second part120may be in various shapes, such as a cylinder or a cuboid.

In the battery10, the battery module200includes a box assembly210and a plurality of battery cells220. The box assembly210is configured to fix the plurality of battery cells220. The plurality of battery cells220may be connected in series, parallel, or series-and-parallel pattern. The series-and-parallel pattern means a combination of series connection and parallel connection of the plurality of battery cells220. The plurality of battery cells220may be directly connected in series, parallel, or series-and-parallel pattern, and then the whole of the plurality of battery cells220is fixed by the box assembly210. Alternatively, in the battery10, a plurality of battery cells220are connected in series, parallel, or series-and-parallel pattern to form a battery module first, and then a plurality of battery modules200are connected in series, parallel, or series-and-parallel pattern to form a whole for being accommodated in the box100. The battery10may further include other structures. For example, the battery10may further include a busbar component. The busbar component is configured to implement electrical connection between the plurality of battery cells220.

Each battery cell220may be, but is not limited to, a secondary battery or primary battery; or, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery. The battery cell220may be in the shape of a cylinder, flat body, cuboid, or the like. The battery cell220is a minimum unit for making up a battery10. The battery cell220may further include a housing, an electrode assembly, a top cover, and other functional components.

According to some embodiments of this application, referring toFIG.3in conjunction withFIG.4toFIG.6.FIG.3is a schematic structural diagram of a battery module200viewed from a first viewing angle according to some embodiments of this application;FIG.4is a schematic exploded view of a battery module200according to some embodiments of this application;FIG.5is a schematic structural diagram of a battery module200viewed from a second viewing angle according to some embodiments of this application; andFIG.6is a schematic structural diagram of a partition piece212according to some embodiments of this application.FIG.3andFIG.4illustrate a scenario in which the battery cell220is rectangular. This application provides a box assembly210. The box assembly210is configured to fix a plurality of battery cells220. The box assembly210includes two end plates211and a partition piece212. The two end plates211are arranged apart along a preset direction and opposite to each other. The partition piece212includes a main body2121and a stress relief piece2122. The main body2121is disposed between the two end plates211along the preset direction. The stress relief piece2122is disposed at two ends of the main body2121in the preset direction and forms a corner g between the stress relief piece and the main body2121. Each stress relief piece2122is fixedly connected to a corresponding end plate211.

As shown in the drawing, the first direction F1in the drawing is a width direction of the battery module200, the second direction F2is a length direction of the battery module200, and the third direction F3is a height direction of the battery module200.

It is hereby noted that the “preset direction” the first direction F1shown in the drawing. The main body2121of the partition piece212is disposed between the two end plates211along the preset direction. After a plurality of battery cells220are placed between the two end plates211, the partition piece212may be sandwiched between adjacent battery cells220. The number of partition pieces212is at least one. One partition piece212or a plurality of partition pieces212may be disposed between adjacent battery cells220. For example, in a scenario shown inFIG.3andFIG.4, a plurality of battery cells220are arranged in parallel along the second direction F2and two rows of battery cells220are disposed. Each row of battery cells220includes a plurality of battery cells220arranged along the first direction F1. One partition piece212is disposed between the two rows of battery cells220. The position and quantity of the partition pieces212may be set depending on the arrangement of the plurality of battery cells220. Any position and quantity are appropriate as long as the main body2121of the partition piece212is disposed between the two end plates211. The position and quantity of the partition pieces are not limited herein.

“Stress relief piece2122” is a component that releases energy to reduce the stress exerted on the box assembly210equipped with the stress relief piece2122. In the technical solution in an embodiment of this application, because the stress relief pieces2122are disposed at the two ends of the main body2121of the partition piece212in the preset direction respectively, a corner g is formed between each of the two stress relief pieces2122and the main body2121of the partition piece212. The formed corner g weakens the local rigidity of the partition piece212. When the main body2121of the partition piece212encounters an expansion force along a preset direction, at least a part of an acting force of the expansion force is relieved at the corner g before the acting force exerted by the expansion force on the main body2121of the partition piece212is transmitted to the junction between the stress relief piece2122and the end cap. When the box assembly210is impacted by to an external impact force, the stress on the junction between the stress relief piece2122and the end cap is directly transmitted to the corner g. At least a part of the received stress is relieved at the corner g.

The stress relief piece2122is disposed at the two ends of the main body2121of the partition piece212, the main body2121is connected to the end plate211by use of the stress relief piece2122, and the corner g is formed between the stress relief piece2122and the main body2121. In this way, when the battery module200is subjected to stress, whether before or during action of the stress, at least a part of the stress can be relieved through the corner g formed between the stress relief piece2122and the main body2121, thereby reducing stress concentration at the stress relief piece2122and a corresponding position on the end plate211, and in turn, improving reliability of connection between the partition piece212and the end plate211. In this way, the structural reliability of the battery module200is effectively improved.

According to some embodiments of this application, optionally, still referring toFIG.6, the stress relief piece2122is configured to be formed in one piece by bending a corresponding end of the main body2121. It is hereby noted that the bending directions of the two ends of the main body2121of the partition piece212may be the same or different. For example, as shown inFIG.6, the two ends of the main body2121of the partition piece212are bent in the same direction, that is, both bent toward the second direction F2. Selection may be made depending on practical applications, without being particularly limited herein.

With the stress relief piece2122being formed in one piece by bending a corresponding end of the main body2121, it is convenient to form a corner g between the stress relief piece2122and the main body2121. In this way, the partition piece212formed in one piece is not only simple to manufacture, but also ensures a specified level of structural strength.

Definitely, according to some other embodiments of this application, optionally, the stress relief piece2122and the main body2121may be discrete structures. In other words, the stress relief piece2122may be fixedly connected to the corresponding end of the main body2121of the partition piece212by a fastening means such as welding. Selection may be made depending on practical applications, without being particularly limited herein.

According to some embodiments of this application, optionally, a bending angle α of the stress relief piece2122is α. The bending angle satisfies: 87°≤α≤93°. When the bending angle α is 90°, the stress relief piece2122can form a good fit with the corresponding end plate211, thereby improving the connection strength between the stress relief piece and the end plate. A bending error may occur at the time of bending to form the stress relief piece2122. Therefore, the bending angle α may be set to a value falling within a range of 87° to 93°. With the bending angle α falling within the above range, not only the desired corner g can be formed, but also the stress relief piece2122can be fixedly connected to the corresponding end plate211conveniently. For example,FIG.6shows a circumstance in which the bending angle α of the stress relief piece2122is 90°. The specific bending angle α may depend on the actual manufacturing process and usage requirements, and is not particularly limited herein.

According to some embodiments of this application, optionally, referring toFIG.7in conjunction withFIG.8toFIG.9,FIG.7is a schematic structural diagram of a battery module200viewed from a third viewing angle according to some embodiments of this application,FIG.8is a schematic exploded view of a battery module200viewed from a third viewing angle according to some embodiments of this application; andFIG.9is a close-up view of a part A shown inFIG.8according to some embodiments of this application. An opening2111is created on each end plate211. The stress relief piece2122located at each of two opposite ends of the main body2121protrudes out of the corresponding end plate211through the opening2111. In other words, the stress relief piece2122is formed outside the end plate211. It is hereby noted that “outside the end plate211” means locations beyond the sides of the two end plates211, the sides being oriented away from each other. Such arrangement causes the stress relief piece2122to be formed outside the end plate211, thereby making it more convenient to connect the stress relief piece2122and the corresponding end plate211together.

According to some embodiments of this application, optionally, still referring toFIG.9in conjunction withFIG.8, grooves2112recessed toward each other are created on a side of one of the two end plates211and a side of the other of the two end plates respectively, the two sides being oriented away from each other. The opening2111is created on bottom walls21121of the grooves2112. Because the opening2111is created on the bottom wall21121of the groove2112, the stress relief piece2122can be accommodated in the groove2112after protruding out of the corresponding end plate211through the opening2111. When encountering stress such as an external impact force, the connection structure between the stress relief piece2122and the corresponding end plate211can be further protected.

According to some embodiments of this application, optionally, the stress relief piece2122is fixedly connected to the corresponding end plate211by welding. The welding process can fixedly connect the stress relief piece2122and the corresponding end plate211together. Specifically, in some embodiments, the welding process includes at least one of laser filler wire welding or cold metal transfer welding. In the box assembly210in such embodiments of this application, the welding process for fixedly connecting the stress relief piece2122and the corresponding end plate211together is flexible, and any welding process is appropriate as long as the welding makes it convenient to fixedly connect the stress relief piece2122and the corresponding end plate211together. As an implementation, after the stress relief piece2122protrudes out of the corresponding end plate211through the opening2111and is bent, the stress relief piece2122is fixed to the corresponding end plate211by laser filler wire welding. This not only increases the welding strength, but also avoids microcracks generated inside the weld.

According to some embodiments of this application, optionally, referring toFIG.10in conjunction withFIG.11,FIG.10is a close-up view of a part A shown inFIG.8according to some other embodiments of this application; andFIG.11is a close-up view of connection between a bending portion and an end cap according to some embodiments of this application.

The dimension of the opening2111along the second direction F2is a first dimension d1, the dimension of the partition piece212along the second direction F2is a second dimension d2, and the first dimension d1is larger than the second dimension d2. The dimension of the opening2111along the third direction F3is a third dimension d3, the dimension of the partition piece212along the third direction F3is a fourth dimension d4, and the third dimension d3is larger than the fourth dimension d4. In this way, the stress relief piece2122is caused to protrude out of the corresponding end plate211through the opening2111.

Specifically, in some embodiments, when the stress relief piece2122and the corresponding end plate211are fixed together by means such as welding, the stress relief piece2122can be fully lap-jointed onto the bottom wall21121of the groove2112on the corresponding end plate211, or partially lap-jointed onto the bottom wall21121of the groove2112on the corresponding end plate211. For example,FIG.9shows a scenario in which the stress relief piece2122is fully lap-jointed onto the bottom wall21121of the groove2112on the corresponding end plate211, andFIG.10andFIG.11show a scenario in which the stress relief piece2122is partially lap-jointed onto the bottom wall21121of the groove2112on the corresponding end plate211. In this way, a lap-joint is formed, making it convenient to form a weld h by welding and fasten the stress relief piece2122and the corresponding end plate211together.

According to some embodiments of this application, optionally, the stress relief piece2122is fixedly connected to the corresponding end plate211by riveting. The riveting process can fixedly connect the stress relief piece2122and the corresponding end plate211together. In the riveting process, the stress relief piece2122may also be fully or partially lap-jointed. Selection may be made depending on practical applications, without being particularly limited herein.

According to some other embodiments of this application, optionally, referring toFIG.12,FIG.12is a close-up view of connection between a bending portion and an end cap according to some other embodiments of this application. The stress relief piece2122may be formed inside the end plate211instead. Understandably, similar to the explanation of the phrase “outside the end plate211” in some preceding embodiments, the phrase “inside the end plate211” means a location on the sides of the two end plates211, the sides being oriented toward each other, that is, a part between the two end plates211. In other words, without a need to create an opening2111on each end plate211, the fixation to the stress relief piece2122is directly performed at the part between the two end plates211. The arrangement may be performed depending on practical applications, without being particularly limited herein.

Specifically, in some embodiments, optionally, still referring toFIG.12, grooves2112recessed away from each other are created on a side of one of the two end plates211and a side of the other of the two end plates respectively, the two sides being oriented toward each other. The stress relief piece2122formed by bending abuts on the bottom wall21121of the groove2112. The stress relief piece2122may be accommodated in the groove2112. When encountering stress such as an external impact force, the connection structure between the stress relief piece2122and the corresponding end plate211can be further protected.

According to some embodiments of this application, optionally, still referring toFIG.3,FIG.5, andFIG.8, a plurality of weight reduction grooves2113recessed toward each other are created on a side of one of the two end plates211and a side of the other of the two end plates respectively, the two sides being oriented away from each other. In this way, not only the weight of the box assembly210can be reduced, but also materials can be saved.

According to some embodiments of this application, optionally, referring toFIG.13in conjunction withFIG.3,FIG.4, andFIG.8,FIG.13is a close-up view of a part B shown inFIG.8according to some embodiments of this application. The box assembly210further includes two side plates213. The two side plates213are arranged apart along a direction perpendicular to the preset direction (that is, along the second direction F2shown in the drawing) and are opposite to each other. Two ends of each of the side plates213along the direction perpendicular to the preset direction are fixedly connected to corresponding end plates211respectively. In this way, by disposing the two side plates213, the box assembly210closes in to form a mounting cavity configured to fix a plurality of battery cells220.

According to some embodiments of this application, optionally, the side plate213is fixedly connected to the corresponding end plate211by welding or riveting. In the box assembly210in such embodiments of this application, the fastening manner for fixedly connecting the side plate213and the corresponding end plates211together is flexible, and any fastening manner is appropriate as long as the manner makes it convenient to fasten the side plate213and the corresponding end plates211together. In the example shown inFIG.13, the end plate211protrudes along the second direction F2to form protruding portions2114, and the two ends of the side plate213along the first direction F1fixedly abut on the corresponding protruding portions2114respectively. In this way, due to the protruding portions2114disposed, when encountering stress such as an external impact force, the connection structure between the side plate213and the corresponding end plate211can be further protected.

According to some embodiments of this application, this application further provides a battery module200. The battery module includes a plurality of battery cells220and the box assembly210disclosed in any one of the foregoing technical solutions. A mounting cavity is formed in the box assembly210, and the mounting cavity is configured to fix the plurality of battery cells220. In this way, due to the use of the box assembly210disclosed in any one of the foregoing technical solutions, when the battery module200is subjected to stress, at least a part of the stress can be relieved through the corner g formed between the stress relief piece2122and the main body2121, thereby reducing stress concentration at the stress relief piece2122and a corresponding position on the end plate211, and in turn, improving reliability of connection between the partition piece212and the end plate211, and effectively improving structural reliability of the battery module200.

According to some embodiments of this application, this application further provides a battery10. The battery includes the battery module200disclosed in any one of the foregoing technical solutions. In this way, due to the use of the battery module200disclosed in any one of the foregoing technical solutions, the reliability of the battery module200is high, and therefore, the reliability of the battery10is improved.

According to some embodiments of this application, this application further provides an electrical device. The electrical device includes the battery10disclosed in any one of the foregoing technical solutions, and the battery10is configured to provide electrical energy for the electrical device. In this way, due to the use of the battery10disclosed in any one of the foregoing technical solutions, the reliability of the battery10is high, and therefore, the reliability of the electrical device is improved.

The electrical device may be any device or system in which the battery10is applied.

According to some embodiments of this application, referring toFIG.3toFIG.6in conjunction withFIG.8andFIG.9, this application provides a box assembly210disposed in a two-row battery module200and configured to fix the battery cells220arranged in two rows. The box assembly210includes a partition piece212, two end plates211, and two side plates213. The two end plates211are arranged apart along a first direction F1and opposite to each other. The two side plates213are arranged apart along a second direction F2and opposite to each other. Two ends of each of the side plates213along the second direction F2are fixedly connected to corresponding end plates211respectively. One partition piece212is disposed between the two rows of battery cells220. The partition piece212includes a main body2121and a stress relief piece2122. The main body2121is disposed between the two end plates211along the first direction F1. The stress relief piece2122is disposed at two ends of the main body2121in the first direction F1and forms a corner g between the stress relief piece and the main body2121. Grooves2112recessed toward each other are created on a side of one of the two end plates211and a side of the other of the two end plates respectively, the two sides being oriented away from each other. The opening2111is created on bottom walls21121of the grooves2112. The stress relief pieces2122located at the two opposite ends of the main body2121protrude out of the corresponding end plates211through the opening2111. The stress relief pieces2122are accommodated in the grooves2112after protruding out of the corresponding end plates211through the opening2111. Each stress relief piece2122is lap-jointed to the bottom wall21121of the groove2112of the corresponding end plate211. Each stress relief piece2122is fixedly connected to the corresponding end plate211by a laser filler wire welding process.

According to some embodiments of this application, referring toFIG.3toFIG.6, an assembling process of a box assembly210according to this application may be as follows:1. Assembling a partition piece212and two end plates211into position;2. Combining a plurality of battery cells220in groups to form a structure that includes two rows of battery cells220;3. Assembling two side plates213to the two end plates211in one-to-one correspondence;4. Bending a stress relief piece2122in the partition piece212by a bending process;5. Fixedly welding the stress relief piece2122to the corresponding end plate211by a laser filler wire welding process; and6. Fixedly welding the two side plates213to the two end plates211correspondingly. An alternative assembling process is to bend the stress relief piece2122in the partition piece212first by a bending process, and then assemble the two side plates213. The assembling steps may be set depending on requirements in practical applications, without being particularly limited herein.

To sum up, in some embodiments of this application, the structure of the box assembly210is improved in view of the stress such as cell expansion force and external force to be encountered by the battery10in use. A stress relief piece2122is disposed at two ends of the main body2121of the partition piece212, and a corner g is formed between the stress relief piece2122and the main body2121. The stress relief piece2122is connected to the corresponding end plate211. In this way, when the battery module200is subjected to stress, at least a part of the stress can be relieved through the corner g formed between the stress relief piece2122and the main body2121, thereby reducing stress concentration at the stress relief piece2122and a corresponding position on the end plate211, and in turn, improving reliability of connection between the partition piece212and the end plate211, and effectively improving structural reliability of the battery module200.

Finally, it is hereby noted that the foregoing embodiments are merely intended to describe the technical solutions of this application but not to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, a person of ordinary skill in the art understands that modifications may still be made to the technical solutions described in the foregoing embodiments, or equivalent replacements may still be made to some or all technical features in the technical solutions. Such modifications and equivalent replacements fall within the scope of the claims and specification hereof without making the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of this application. Particularly, to the extent that no structural conflict exists, various technical features mentioned in different embodiments may be combined in any manner. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.