CELL, BATTERY MODULE, BATTERY PACK, AND ELECTRIC VEHICLE

A cell includes a housing and at least one electrode core assembly array encapsulated inside the housing. The electrode core assembly array includes N rows and M columns of electrode core assemblies, and the electrode core assembly includes an encapsulation film and at least one electrode core encapsulated inside the encapsulation film. The electrode core assemblies are arranged in rows, and each row includes M electrode core assemblies. The electrode core assemblies are arranged in columns, and each column includes N electrode core assemblies. The N electrode core assemblies in each column are connected in series to form an electrode core assembly string. The M electrode core assembly strings are connected in series. An air pressure between the metal housing and the encapsulation film is lower than an air pressure outside the metal housing.

FIELD

The present disclosure belongs to the battery field, and more specifically, relates to a cell, a battery module, a battery pack, and an electric vehicle.

BACKGROUND

Currently, battery packs applied to electric vehicles generally include a plurality of cells, to improve capacities of the cells. The plurality of cells are mounted in a housing of the battery pack.

The cell in the related art generally includes a housing and electrode cores encapsulated in the housing. There is also a solution in which a plurality of electrode cores are connected in series, to improve a voltage of the cell. However, the current solution of serial connection has a specific safety problem in an actual application.

SUMMARY

The present disclosure resolves at least one of the technical problems existing in the related art. For this purpose, the present disclosure provides a cell with higher safety performance.

The present disclosure further provides a battery module.

The present disclosure further provides a battery pack and an electric vehicle using the battery pack.

The cell of the present disclosure includes a housing and at least one electrode core assembly array encapsulated in the housing. The at least one electrode core assembly array comprises N rows and M columns of electrode core assemblies, and each of the electrode core assemblies comprises an encapsulation film and at least one electrode core encapsulated in the encapsulation film. Electrode core assemblies of a row are arranged along a length direction of the cell, and each of the N rows comprises M electrode core assemblies. Electrode core assemblies in a column are arranged along a thickness direction or a height direction of the cell, and each of the M columns comprises N electrode core assemblies. The N electrode core assemblies in each column are connected in series to form an electrode core assembly string. The M electrode core assembly strings are connected in series. M and N are integers greater than 1. An air pressure between the housing and the encapsulation film is lower than an air pressure outside the housing.

In the cell of the present disclosure, the electrode core is first encapsulated in the encapsulation film and then is encapsulated into the housing, to achieve a double seal, so that a sealing effect may be effectively improved by using a double-layer sealing effect of the encapsulation film and the housing. In addition, the air pressure between the housing and the encapsulation film is lower than the air pressure outside the housing, so that the housing is as close as possible to the internal electrode core assembly, to reduce an internal gap, thereby preventing the electrode core assembly from moving in the housing and avoiding a relative displacement between the electrode core assemblies. Therefore, cases such as current collector damage, folding of a membrane, and falling of an active material are reduced, the mechanical strength of the entire cell is improved, a service life of the cell is prolonged, and the safety performance of the cell is improved. In addition, through the arrangement manner of the electrode core assemblies of the present disclosure, a relatively long cell may be manufactured more conveniently, to reduce the costs and further ensure that the heat dissipation efficiency of the cell is improved. Therefore, by using the solution of the present disclosure, the relatively long and strong cell may be easily implemented, so that when the cell is mounted into a housing of a battery pack, arrangement of support structures such as a cross beam and a longitudinal beam in the battery pack may be reduced. The cell is directly mounted in the housing of the battery pack by using the cell as a support, to reduce an internal space of the battery pack, thereby improving volume utilization of the battery pack and reducing the weight of the battery pack.

Additional aspects and advantages of the present disclosure will be given in the following description, some of which will become apparent from the following description or may be learned from practices of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described in detail below, and examples of the embodiments are shown in the accompanying drawings, where the same or similar elements or the elements having same or similar functions are denoted by the same or similar reference numerals throughout the description. The embodiments described below with reference to the accompanying drawings are exemplary and used only for explaining the present disclosure, and should not be construed as a limitation on the present disclosure.

As shown inFIG.1toFIG.4, the present disclosure provides a cell100, for example, used for forming a battery pack. The cell100includes a housing11and at least one electrode core assembly array14encapsulated inside the housing11. In some embodiments, the housing may be a metal housing. The electrode core assembly array14includes N rows and M columns of electrode core assemblies12. Each of the electrode core assemblies12includes an encapsulation film and at least one electrode core encapsulated inside the encapsulation film. In a length direction of the cell100, the electrode core assemblies12are arranged in rows and each row includes M electrode core assemblies12. In a thickness or height direction of the cell100, the electrode core assemblies12are arranged in columns and each column includes N electrode core assemblies12. The N electrode core assemblies12in each column are connected in series to form an electrode core assembly string13. The M electrode core assembly strings13are connected in series. M and N are integers greater than 1. An air pressure between the housing11and the encapsulation film is lower than an air pressure outside the housing11.

In the cell of the present disclosure, the electrode core is first encapsulated in the encapsulation film and then is encapsulated into the housing11, to achieve a double seal, so that a sealing effect may be effectively improved by using a double-layer sealing effect of the encapsulation film and the housing11. In addition, the air pressure between the housing11and the encapsulation film is lower than the air pressure outside the housing11, so that the housing11is as close to the internal electrode core assembly12as possible, to reduce an internal gap, thereby preventing the electrode core assembly12from moving in the housing11and avoiding a relative displacement between the electrode core assemblies12. Therefore, cases such as current collector damage, folding of a membrane, and falling of an active material are reduced, the mechanical strength of the entire cell is improved, a service life of the cell is prolonged, and the safety performance of the cell is improved. In addition, through the arrangement manner of the electrode core assemblies of the present disclosure, a relatively long cell may be manufactured more conveniently, to reduce the costs and further ensure that the heat dissipation efficiency of the cell is improved. Therefore, by using the solution of the present disclosure, the relatively long and strong cell may be easily implemented, so that when the cell is mounted into a housing of a battery pack, the arrangement of support structures such as a cross beam and a longitudinal beam in the battery pack may be reduced. The cell is directly mounted in the housing of the battery pack by using the cell as a support, to reduce an internal space of the battery pack, thereby improving the volume utilization of the battery pack and reducing the weight of the battery pack.

As shown inFIG.1toFIG.4, in this embodiment, a length of the electrode core assembly12extends along the length direction of the cell. The electrode core assembly12includes a first electrode lead-out member121and a second electrode lead-out member122respectively extending from two ends of the electrode core assembly12along a length direction and configured to lead out a current. Quantities of first electrode lead-out members121and second electrode lead-out members122are not limited, and only two electrode lead-out members with different electrode cores are represented herein. A first electrode lead-out member121of one electrode core assembly12of two adjacent electrode core assemblies12in each column is electrically connected to a second electrode lead-out member122of the other electrode core assembly12of the two adjacent electrode core assemblies.

For example, a first electrode lead-out member121of one electrode core assembly12of two adjacent electrode core assemblies12in each column and a second electrode lead-out member122of the other electrode core assembly12of the two adjacent electrode core assemblies are arranged on a same side of the column, to achieve a simpler connection, thereby further improving the safety performance of the cell and reducing the costs of the cell. The connection between the first electrode lead-out member121and the second electrode lead-out member122may be a direct connection or an indirect connection such as connection by a conductive member.

As shown inFIG.2toFIG.4, in this embodiment, an electrode core assembly12at a tail end of one electrode core assembly string13of two adjacent electrode core assembly strings13is electrically connected to an electrode core assembly12at a tail end of the other electrode core assembly string13of the two adjacent electrode core assembly strings. Or a first electrode core assembly12of one electrode core assembly string13of two adjacent electrode core assembly strings13is electrically connected to a first electrode core assembly12of the other electrode core assembly string13of the two adjacent electrode core assembly strings, to implement a serial connection between the electrode core assembly strings13. A first electrode lead-out member121of an electrode core assembly12at a tail end of one electrode core assembly string13of the two adjacent electrode core assembly strings13is adjacent to a second electrode lead-out member122of an electrode core assembly12at a tail end of the other electrode core assembly string13of the two adjacent electrode core assembly strings. Or a first electrode lead-out member121of a first electrode core assembly12of one electrode core assembly string13of the two adjacent electrode core assembly strings13is adjacent to a second electrode lead-out member122of a first electrode core assembly12of the other electrode core assembly string13of the two adjacent electrode core assembly strings, to achieve a simpler connection, thereby further improving the safety performance of the cell and reducing the costs of the cell. The connection between the first electrode lead-out member121and the second electrode lead-out member122may be a direct connection or an indirect connection such as a connection by a conductive member.

In this embodiment of the present disclosure, the N electrode core assemblies12are arranged along the thickness direction of the cell. A thickness of the electrode core assembly12extends along the thickness direction of the cell. In the series connection manner, the electrode core assembly array14includes a first main electrode141and a second main electrode142configured to lead out a series current. As shown inFIG.3, three electrode core assemblies12arranged along the thickness direction are connected in series. A second electrode lead-out member122of a third electrode core assembly12is connected to a first electrode lead-out member121of a second electrode core assembly12, and the two electrode lead-out members are on a same side. A second electrode lead-out member122of the second electrode core assembly12is connected to a first electrode lead-out member121of a first electrode core assembly12, and the two electrode lead-out members are on a same side. A second electrode lead-out member122of the first electrode core assembly12is configured to be electrically connected to a next electrode core assembly string13.

As shown inFIG.3, the three electrode core assemblies are connected to form S-shaped electrode core assembly strings13. In the formed electrode core assembly strings13, that is, a second electrode lead-out member122of a first electrode core assembly12of a first electrode core assembly string13is connected to a first electrode lead-out member121of a first electrode core assembly12of a second electrode core assembly string13, and the two electrode lead-out members are adjacent. Then, in the second electrode core assembly string13, a second electrode lead-out member122of the first electrode core assembly12is connected to a first electrode lead-out member121of a second electrode core assembly12, and the two electrode lead-out members are on a same side. A second electrode lead-out member122of the second electrode core assembly12is connected to a first electrode lead-out member121of a third electrode core assembly12, and the two electrode lead-out members are on a same side. A second electrode lead-out member122of the third electrode core assembly12is configured to be electrically connected to a next electrode core assembly string13.

The second electrode lead-out member122of the third electrode core assembly12of the second electrode core assembly string13is connected to a first electrode lead-out member121of a third electrode core assembly12of the third electrode core assembly string13, and the two electrode lead-out members are adjacent. Then, in the third electrode core assembly string13, a second electrode lead-out member122of the third electrode core assembly12is connected to a first electrode lead-out member121of a second electrode core assembly12, and the two electrode lead-out members are on a same side. A second electrode lead-out member122of the second electrode core assembly12is connected to a first electrode lead-out member121of a first electrode core assembly12, and the two electrode lead-out members are on a same side. A second electrode lead-out member122of the first electrode core assembly12is configured to lead out a second main electrode142.

A first electrode lead-out member121of a third electrode core assembly12of the first electrode core assembly string13is configured to lead out a first main electrode141The first main electrode141and the second main electrode142respectively extend from two opposite corners of the electrode core assembly array14. The connection relationship is described from only the accompanying drawings herein, and a specific connection sequence during preparation is not limited in this embodiment and may be adjusted according to an actual situation.

As shown inFIG.4, the obtained electrode core assembly arrays14may be connected in series. A second main electrode142of a first electrode core assembly array14is connected to a first main electrode142of a second electrode core assembly array14, and the two main electrodes are on a same side and are better adjacent. In another embodiment, serial connection is not limited between two electrode core assembly arrays14, and a plurality of electrode core assembly arrays14may be connected in series. Values of M and N in each electrode core assembly array14may be the same or may be different, that is, quantities of electrode core assemblies in each electrode core assembly array14may be the same or may be different.

In the present disclosure, the electrode core may be an electrode core commonly used in the field of power batteries and may be an electrode core formed by winding or may be an electrode core made by lamination. Generally, the electrode core includes at least a positive electrode plate, a membrane, and a negative electrode plate. In the present disclosure, one or more electrode cores may be provided in the electrode core assembly. Generally, a plurality of electrode cores are connected in parallel. It should be noted that, the electrode core assembly shall not be understood as the cell. The cell mentioned in the present disclosure is an independent single cell and shall not be simply understood as a battery module300or a battery assembly because the cell includes a plurality of electrode core assemblies.

The first electrode lead-out member121and the second electrode lead-out member122of the electrode core assembly12respectively extend from the encapsulation film. If the electrode core assembly12includes only one electrode core, the first electrode lead-out member121and the second electrode lead-out member122may be respectively an anode tab and a cathode tab of the electrode core or may be respectively a cathode tab and an anode tab. If the electrode core assembly includes a plurality of electrode cores, the first electrode lead-out member121may be a lead-out member formed by compounding and welding the anode tabs, and the second electrode lead-out member122may be a lead-out member formed by compounding and welding the cathode tabs. In an embodiment, the first electrode lead-out member121may be a lead-out member formed by compounding and welding the cathode tabs, and the second electrode lead-out member122may be a lead-out member formed by compounding and welding the anode tabs. The “first” and “second” in the first electrode lead-out member121and the second electrode lead-out member122are merely used for distinguishing name but are not used for limiting quantities. For example, one or more first electrode lead-out members121may be provided.

The housing11includes a housing body111having an opening and a cover plate112connected to the opening in a sealed manner. The cover plate112and the housing body111enclose a sealed accommodating cavity, and the electrode core assembly array14is arranged in the accommodating cavity. The first main electrode141and the second main electrode142are led out from the cover plate112. The quantity of cover plates112is not limited in the present disclosure and one or two cover plates may be provided. A position of the opening in the housing body111and the quantity of cover plates112may be designed according to the design of the internal electrode core assembly array14.

In some implementations, the housing body111may be provided with openings at two ends, and two cover plates112may be provided, so that the two cover plates112are respectively connected to the openings at two ends of the housing body111in a sealed manner, to form the sealed accommodating cavity. In this manner, the first main electrode141and the second main electrode142of the electrode core assembly array14may be led out from the same cover plate112or may be respectively led out from two cover plates112. This is not limited. In some implementations, the housing body111may be provided with an opening at only one end, and one cover plate112is provided, so that the cover plate112is connected to the opening at one end of the housing body111in a sealed manner. In this manner, the first main electrode141and the second main electrode142of the electrode core assembly array14are led out from the same cover plate112.

In this embodiment of the present disclosure, the electrode core is encapsulated in the encapsulation film, that is, the encapsulation film is further arranged between the housing11and the electrode core. Therefore, a double encapsulation on the electrode core may be implemented by using the encapsulation film and the housing11, which is beneficial to improving the sealing effect of the cell. Generally, an electrolyte solution is inside the encapsulation film. Therefore, in this manner, the electrolyte solution may be prevented from being in contact with the housing11, to avoid corrosion of the housing11or decomposition of the electrolyte solution. An air pressure between the housing11and the encapsulation film is lower than an air pressure outside the housing11. In the present disclosure, the “air pressure” is an abbreviation of an atmospheric pressure and is applied on a unit area, that is, it is equal to a weight of a vertical air column extending upward to an upper bound of an atmosphere per unit area. The air pressure between the housing11and the encapsulation film is an air pressure in a space between the housing11and the encapsulation film, and the air pressure is lower than the air pressure outside the housing11. Therefore, in this embodiment of the present disclosure, a space between the housing11and the encapsulation film is in a negative pressure state, so that the housing11is recessed or deformed under the action of air pressure, and a gap between the housing11and the electrode core assembly is reduced. A space for movement of the electrode core assemblies or displacement between the electrode core assemblies is reduced, to reduce the movement of the electrode core assemblies and a relative displacement between the electrode core assemblies, thereby improving the stability of the cell100and improving the strength of the cell100and the safety performance of the cell100.

For example, air extraction processing may be performed on the space between the housing11and the encapsulation film, so that the space between the housing11and the encapsulation film is in the negative pressure state. Therefore, the housing11may be as close as possible to the internal electrode core assembly, to reduce the internal gap, thereby preventing the electrode core assembly from moving in the housing and avoiding the relative displacement between the electrode core assemblies. Therefore, cases such as current collector damage, folding of a membrane, and falling of an active material are reduced, the mechanical strength of the entire cell is improved, a service life of the cell is prolonged, and the safety performance of the cell is improved.

In an implementation, the air pressure between the housing11and the encapsulation film is P1, and a value of P1may range from −100 kPa to −5 kPa.

Certainly, a person skilled in the art may set the value of P1according to an actual requirement. For example, the value of P1may range from −75 kPa to −20 kPa. It should be noted that, the space between the housing11and the encapsulation film may be in a vacuum state.

An air pressure within the encapsulation film is P2, and a relationship between P1and P2satisfies that P1/P2ranges from 0.05 to 0.85. A value of P2may range from −100 kPa to −20 kPa.

P1, P2, and P1/P2are limited in the range. The electrode core in this technology adopts a double sealing mode. The electrode core is first encapsulated in the encapsulation film. To avoid damage to the encapsulation film caused by outward bulge of the encapsulation film due to an excessively large internal air pressure, the air pressure between the housing11and the encapsulation film is higher than the air pressure within the encapsulation film. In addition, it is verified through a large number of experiments that when P1/P2is in the range, the reliability of the double sealing of the cell is better. Moreover, an interface between electrode plates of the cell is ensure, and a gap between the electrode plates is avoided, to enable a lithium ion to be better conducted.

In some implementations, the air pressure within the encapsulation film is lower than the air pressure between the housing11and the encapsulation film.

In the arrangement manner in the present disclosure, every two electrode core assemblies12may be connected in series conveniently, and a connection structure is simple. In addition, in the arrangement manner, a relatively long cell100may be manufactured conveniently. Therefore, the cell100may be mounted in a housing of a battery pack without support structures such as a cross beam and a longitudinal beam, and the cell100is directly mounted in the housing of the battery pack by using the housing11of the cell100as a support. Therefore, the internal space of the battery pack may be reduced, thereby improving the volume utilization of the battery pack and reducing the weight of the battery pack.

The cell is substantially a cuboid, and a length L of the cell ranges from 400 mm to 2500 mm (millimeter), for example, may be 500 mm, 1000 mm, or 1500 mm. In a manner in which a plurality of electrode core assemblies are arranged in the cell, a relatively long cell may be manufactured more conveniently compared with an existing manner in which only one electrode core is arranged. In a conventional cell, once the cell is relatively long, a length of a copper-aluminum foil used as a current collector inside the cell is increased correspondingly, which greatly increases the internal resistance of the cell and cannot meet current requirements for a high power and fast charging. In a case that the lengths of the cells are the same, in this embodiment of the present disclosure, the internal resistance of the cell may be greatly reduced, to avoid problems caused by overheating of the cell under the conditions of high power output and fast charging.

A thickness D of the cell may be greater than 10 mm, for example, may range from 13 mm to 75 mm. In this embodiment of the present disclosure, a ratio of the length of the cell to the thickness of the cell ranges from 5 to 250.

In this embodiment of the present disclosure, the cell is provided with two opposing first surfaces113along the thickness direction of the cell. The first surfaces113are largest surfaces of the cell, that is, “large surfaces” of the cell. At least one first surface113is recessed toward the inside of the housing11, so that the housing11may be as close as possible to the electrode core assembly.

Because the housing11has a relatively small thickness and is a relatively thin sheet, a recess114on the first surface113of the cell may be, for example, a recess formed by performing air extraction on the inside of the housing11. That is, air extraction processing is performed on the space between the housing11and the encapsulation film, so that when the air pressure between the housing11and the encapsulation film is lower than the air pressure outside the housing11, the first surface113of the cell is easily recessed toward the inside of the housing11to form the recess114as air extraction is performed.

During the normal use of the cell, the cell usually expands due to expansion of a material, gas production of the electrolyte solution, or the like, and a region that expands and is deformed greatly is the large surface of the cell. By using the technology, the large surface of the cell is limited to be slightly recessed inward by vacuuming when the cell is in an initial state, which can effectively relieve extrusion between the cells after the cell expands, thereby improving the service life and the safety performance of the cell and the entire system.

In some other embodiments, as shown inFIG.5, a recess may be formed on the first surface113of the housing11in advance, then the air extraction processing is performed on the inside of the housing11. A plurality of recesses114may be provided on the first surface113of the housing11. For example, a plurality of recesses114are formed on the first surface113in advance, and a position of each recess corresponds to a position of one electrode core assembly.

In some implementations, the two opposing first surfaces113of the cell are both recessed toward the inside of the housing, to clamp the electrode core assembly by using recessed regions.

An exhaust hole may be provided on the housing11. An air extraction operation is performed on the space between the housing11and the encapsulation film by using the exhaust hole. The exhaust hole needs to be sealed. Therefore, a sealing member is further arranged inside the exhaust hole, to seal the exhaust hole. The sealing member may be, for example, a plug or a rubber member. This is not limited.

In some implementations, before the air extraction is performed on the housing11, a gap is provided between the electrode core assembly and an inner surface of the housing11. The gap facilitates convenient mounting of the electrode core assembly into the housing11. After the air extraction is performed on the housing11, the housing11is pressed on an outer surface of the electrode core assembly along a second direction to clamp the electrode core assembly, to reduce a space for the electrode core assembly to move inside the housing, thereby improving the safety performance of the cell.

The aluminum plastic film has a relatively poor heat dissipation effect and a low strength and is limited by a manufacturing process. A cell100with a relatively large thickness cannot be prepared by using the aluminum plastic film as a housing of the cell100. In this embodiment of the present disclosure, different from the existing aluminum plastic film, the housing11has a high strength and a good heat dissipation effect, and the housing11may include, but not limited to, an aluminum housing or a steel housing.

In some embodiments, a thickness of the housing11ranges from 0.05 mm to 1 mm. When the thickness of the housing11is relatively large, the weight of the cell100may be increased, a capacity of the cell100is reduced, and the present disclosure is not easily implemented. In this embodiment, the thickness of the housing11may be selected from the foregoing range, which not only can ensure the strength of the housing11but also does not reduce the capacity of the cell100. In a negative pressure state, the housing11may be more easily deformed, to reduce a distance between the housing11and the electrode core assembly, thereby reducing movement of the electrode core assembly inside the housing11and the relative displacement between the electrode core assemblies.

In the present disclosure, the encapsulation film is an aluminum-plastic compound film. In an embodiment, the encapsulation film includes a non-metallic outer film and a non-metallic inner film laminated together. The inner film is arranged between the outer film and the electrode core assembly. The inner film has relatively good chemical stability and may be made of, for example, a material with an anti-electrolyte solution corrosion characteristic, which may be a polypropylene (PP), a polyethylene (PE), or a polyethylene terephthalate (PET), or combinations of the materials. The outer film is a protection layer, to prevent penetrations of air, especially water vapor, oxygen, and the like. A material of the outer film may be, for example, polyethylene terephthalate, polyamide (PA), or polypropylene, or combinations of the materials. In the encapsulation film of this embodiment, a melting point of the outer film is higher than a melting point of the inner film. Therefore, when hot melting and sealing are performed, the outer film is not melted, but the inner film can be melted in time to ensure good sealing performance.

A difference between the melting point of the outer film and the melting point of the inner film may range from 30° C. to 80° C. For example, the difference between the melting points may be 50° C., 70° C., or the like. Selection of a specific material may be determined according to an actual requirement. The outer film and the inner film may be bonded by using an adhesive. For example, the material of the outer film may be PP, the material of the inner film may be PET, and a binder for bonding the outer film and the inner film may be, for example, a polyolefin binder, to form a composite film. In this embodiment, the encapsulation film is formed by double layers of non-metallic films to encapsulate the electrode core with a higher tensile strength and elongation rate at break, which may reduce a limitation on the thickness of the cell to obtain a cell with a larger thickness. In this embodiment, the range of the thickness of the cell may be extended, for example, the thickness may be greater than 10 mm, such as a range from 13 mm to 75 mm.

In an embodiment of the present disclosure, the cell is a lithium-ion cell.

As shown inFIG.7, according to another aspect of the present disclosure, a battery module300is provided, including the cell according to any one of the foregoing embodiments. By using the battery module300provided in the present disclosure, the sealing performance is better, the assembly process is simple, and the costs of the cell are relatively low.

Referring toFIG.6andFIG.8, the present disclosure further provides a battery pack200, including a cell array21. The cell array21includes a plurality of cells100. The cell100is the cell100described in any one of the embodiments. Therefore, a specific structure of the cell100is not described herein again.

One or more cell arrays21may be provided, and one or more cells100may be provided in each cell array21. During actual production, the quantity of cells100may be set according to an actual requirement, and the quantity of cell arrays21may also be set according to an actual requirement. This is not specifically limited in the present disclosure.

In this embodiment of the present disclosure, a plurality of cells100are sequentially arranged along the thickness direction B of the cell, to form the cell array21. A gap is provided between at least two adjacent cells100. A ratio of the gap to a thickness of the cell100ranges from 0.001 to 0.15.

It should be noted that, The gap between the two adjacent cells100changes as a working time of the cell increases. However, regardless of whether the cell is working, or after the cell works, or before the cell leaves the factory, the gap falls within the protection scope of the present disclosure as long as that the ratio of the gap between the cells to the thickness is within a range limited in the present disclosure.

In the present disclosure, a specific gap is reserved between the cells100, to reserve a buffer space for expansion of the cell100.

In the present disclosure, the ratio of the gap between the cells100to the thickness of the cell100is limited between 0.001 and 0.15, so that a space of the battery pack200may be fully used, the utilization of the battery pack200is improved, and a better buffer effect may also be achieved for the expansion of the cell100.

In addition, the cell100generates heat during expansion. A specific gap is reserved between the cells100, and the gap may further be served as a heat dissipation channel such as an air channel. A surface with a relatively large area of the cell100has a better heat dissipation effect. Therefore, the heat dissipation efficiency of the battery pack200may further be improved, and the safety performance of the battery pack200is improved.

In the solution, the gap between the cells100may be understood as that no structural member is arranged between the cells100and a specific space is simply reserved, or may be understood as that another structural member is arranged between the cells100to separate the cells100by using the structural member.

It should be noted that, when the structural member is arranged between the cells100, the gap between the cells100should be understood as a distance between the cells100on two sides of the structural member but shall not be understood as a distance between the structural member and the cell100.

It should be noted that gaps may be reserved between the structural member and the cells100on two sides of the structural member, or the structural member may be in direct contact with the cells on two sides of the structural member. When the structural member is in direct contact with the cells100on the two sides, the structural member should have a specific flexibility and may achieve a buffer effect for the expansion of the cell100. The structural member includes, but not limited to, aerogel, a heat conductive structure adhesive, or a heat insulation foam.

In the present disclosure, when a plurality of cell arrays21are provided, the gap should refer to a distance between two adjacent cells100in the same cell array21rather than a distance between two adjacent cells in different cell arrays21. In addition, in the same cell array21, a specific gap may be reserved between two adjacent cells of all cells or a specific gap may be reserved between two adjacent cells of some of the cells.

In an implementation, the gap between the two adjacent cells100includes a first gap d1. The first gap d1is defined as a minimum distance between two cover plates112of two adjacent cells along the thickness direction of the cell. A ratio of the first gap d1to the thickness of the cell ranges from 0.005 to 0.1.

In the implementation, due to a relatively high strength, the cover plate112is not easily expanded compared with the housing body111. Even though after the cell100works for a period of time, a chemical reaction occurs inside the cell, and the cell100expands to squeeze adjacent cells100, the first gap d1changes (for example, gradually increases), but the change is relatively small and may be ignored. In an embodiment, even though the first gap changes, the ratio of the first gap to the thickness of the cell100still meet the range. In the implementation, two ends of the housing body111are respectively provided with the cover plates112. When the cells100are arranged along the thickness direction to form the cell array21, a gap between two cells100may be a minimum distance between two cover plates along the thickness direction of the cell at a same end of the cell array or may be a minimum distance between two cover plates along the thickness direction of the cell at different ends of the cell array.

In an implementation, the gap between the two adjacent cells100includes a second gap. The second gap is a minimum distance between two first surfaces facing each other of two adjacent cells100. The second gap before the cell100is used is larger than the second gap after the cell is used.

“before use” may be understood as that the cell100is to leave the factor or has left the factor after being assembled but does not start providing electric energy to the outside. “after use” may be understood as that after the cell100provides electric energy to the outside. For example, after the battery pack200is assembled on an electric vehicle1000, a state before use may be understood as a state of a new vehicle. A state after use should be a state after the vehicle travels for a certain mileage.

In the implementation, the second gap should refer to a minimum distance between two opposing first surfaces of two adjacent cells100. The distance is gradually reduced as the use time of the cell is increased, which mainly because a distance between two adjacent large surfaces is gradually reduced after the cell expands.

In this embodiment of the present disclosure, the battery pack200further includes a battery cover and a tray22. The battery cover is not shown inFIG.8. The battery cover is connected to the tray22in a sealed manner, to form a battery accommodating cavity, and the cell array21is arranged inside the battery accommodating cavity. The tray22includes a support member221to form a support region on the housing11of the cell100. The cell100is butted with the support member221by the support region, and is supported on the support member221.

The tray22includes side beams. The sides beams are used as support members221. Two ends of the cell100along the length direction A of the cell are respectively supported on the side beams.

In the cell100of the embodiments of the present disclosure, the air pressure between the housing11and the encapsulation film is a negative pressure, and the entire strength of the cell may be improved. Therefore, the cell100may be directly mounted on the tray22by using the strength as a support, so that no structure, such as a cross beam or a longitudinal beam, needs to be arranged on the tray22to support the cell100, thereby improving the utilization of the internal space of the battery pack.

An electric vehicle1000is provided and includes the battery pack200. By using the electric vehicle1000provided in the present disclosure, an endurance capability of the vehicle is high, and the costs are relatively low.

The length direction of the cell is arranged along a length direction of a vehicle body of the electric vehicle1000, and a length of the vehicle body ranges from 500 mm to 5200 mm.

In the descriptions of the present disclosure, it should be noted that, unless otherwise explicitly specified or defined, the terms such as “install”, “connect”, and “connection” should be understood in a broad sense. For example, the connection may be a fixed connection, a detachable connection, or an integral connection; or the connection may be a mechanical connection or an electrical connection; or the connection may be a direct connection, an indirect connection through an intermediary, or internal communication between two components. A person of ordinary skill in the art may understand the specific meanings of the foregoing terms in the present disclosure according to specific situations.

In description of this specification, description of reference terms such as “an embodiment”, “specific embodiments”, or “an example”, means including specific features, structures, materials, or features described in the embodiment or example in at least one embodiment or example of the present disclosure. In this specification, exemplary descriptions of the foregoing terms do not necessarily refer to the same embodiment or example. In addition, the described specific features, structures, materials, or characteristics may be combined in a proper manner in any one or more of the embodiments or examples.

Although the embodiments of the present disclosure have been shown and described, a person of ordinary skill in the art is to be understood that various changes, modifications, replacements, and variations may be made to the embodiments without departing from the principles and spirit of the present disclosure, and the scope of the present disclosure is as defined by the appended claims and their equivalents.