Battery packs and electric vehicles

Abstract

The battery pack and electric vehicle include a battery pack (200) including a battery string (201) including a plurality of cells (100), the thickness of the cells (100) extending along a first direction, the plurality of cells (100) being arranged in order along the first direction to form the battery string (201), at least one cell (100) including a metal case (101) and an electrode assembly (102) packaged within the metal case (101), the air pressure within the metal case (101) being lower than the air pressure outside the metal case (101), a gap being present between at least two adjacent cells (100), and the ratio of the gap to the thickness of the cells (100) being in the range of 0.001 to 0.15.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority from Chinese Patent Application No. "202010033795.1" filed by BD Company Limited on January 13, 2020, entitled "Battery Pack and Electric Vehicle."

[0002] This application is in the field of batteries, and more particularly, battery packs and electric vehicles. [Background technology]

[0003] A battery pack applied to a conventional electric vehicle generally includes a plurality of cells mounted within a battery pack case to improve battery capacity.

[0004] In conventional battery systems, multiple electrode assemblies are connected in series within a battery case to increase the capacity of the battery. When the battery is subject to vibration or shaking, the multiple electrode assemblies tend to move within the case, causing relative displacement between the electrode assemblies and damaging the electrode assemblies, resulting in, for example, broken current collectors, wrinkled separators, and detachment of active material layers from the electrode plates, resulting in poor battery stability and potential safety issues. At the same time, the battery also swells, posing safety risks. Summary of the Invention

[0005] The present application aims to solve at least to some extent one of the technical problems in the related art.

[0006] For this purpose, the first aspect of the present application The battery pack includes a battery string including a plurality of cells; The thickness of the unit cell extends along a first direction, and a plurality of the unit cells are arranged in order along the first direction to form the battery string, at least one of the unit cells includes a metal case and an electrode body packaged within the metal case, the air pressure within the metal case is lower than the air pressure outside the metal case, there is a gap between at least two adjacent unit cells, and the ratio range of the gap to the thickness of the unit cells is 0.001 to 0.15.

[0007] In some embodiments of the present application, the air pressure inside the metal case is −100 Kpa to −5 Kpa.

[0008] In some embodiments of the present application, the air pressure inside the metal case is −90 Kpa to −20 Kpa.

[0009] In some embodiments of the present application, the metal case has a thickness of 0.05 mm to 1 mm.

[0010] In some embodiments of the present application, the metal case includes a case body having an opening and an end cover, the end cover is sealingly connected to the opening of the case body and forms a sealed storage chamber together with the case body, the electrode assembly is located in the storage chamber, a gap between two adjacent cells includes a first gap, the first gap is the smallest distance along a first direction between the two end covers of the two adjacent cells, a thickness of the cell is a dimension of the end cover along the first direction, and a ratio range of the first gap to the thickness of the cell is 0.005 to 0.1.

[0011] In some embodiments of the present application, the metal case includes a case body having an opening and an end cover, the end cover is sealingly connected to the opening of the case body to form a sealed storage chamber together with the case body, the electrode body is located within the storage chamber, the case body has two opposing first surfaces along the first direction, a gap between two adjacent cells includes a second gap, the second gap is the minimum distance between the two opposing first surfaces of the case bodies of the two adjacent cells, and a thickness of the cell is a dimension of the end cover along the first direction.

[0012] In some embodiments herein, the second gap before use of the cell is larger than the second gap after use of the cell.

[0013] In some embodiments of the present application, the metal case has two opposing first surfaces along the first direction, and at least one of the first surfaces is recessed into the interior of the metal case.

[0014] In some embodiments of the present application, both of the two first surfaces are recessed inside the metal case, and the metal case is pressed against the outer surface of the electrode body along the first direction to sandwich the electrode body.

[0015] In some embodiments of the present application, before air is evacuated from the metal case, a gap is provided between the electrode body and the inner surface of the metal case, and after air is evacuated from the metal case, the metal case is pressed against the outer surface of the electrode body along a first direction to clamp the electrode body.

[0016] In some embodiments of the present application, the number of electrode bodies packaged in the metal case is plural, the plural electrode bodies are divided into plural electrode body sets, and the electrode body sets are connected in series.

[0017] In some embodiments of the present application, the length of the single cell extends along the second direction and is 400 mm to 2500 mm, a plurality of the electrode body sets are arranged along the second direction, the length of the electrode body set extends along the second direction, the electrode body set includes a first electrode and a second electrode that draw current, and the first electrode and second electrode are located on either side of the electrode body set along the second direction.

[0018] In some embodiments of the present application, the electrode sets are connected in series to form an electrode array, and a first electrode of one of two electrode sets located at both ends of the electrode array and a second electrode of the other electrode set are respectively drawn out from both ends of the metal case along the second direction.

[0019] In some embodiments of the present application, the thickness D of the cell is greater than 10 mm.

[0020] In some embodiments of the present application, the thickness of the cell is 13 mm to 75 mm.

[0021] In some embodiments of the present application, a packaging film is further provided between the metal case and the electrode body, and the electrode body is packaged in the packaging film.

[0022] In some embodiments of the present application, the number of the electrode bodies is plural, the plural electrode bodies are divided into plural electrode body sets, the number of the packaging films is one, the electrode body sets are connected in series, the plural serially connected electrode body sets are packaged in the same packaging film, the electrode body set includes an electrode body set body, and a first electrode and a second electrode that draw current, and a connection point between the first electrode of one of the two serially connected electrode body sets and the second electrode of the other electrode body set is located within the packaging film.

[0023] In some embodiments of the present application, a package section is formed at a relative position between the package film and the first electrode and / or the second electrode to separate two adjacent electrode body set bodies, and at least one of the first electrode of one of the two adjacent electrode body sets and the second electrode of the other electrode body set is located within the package section.

[0024] In some embodiments of the present application, the number of the electrode bodies is plural, the plural electrode bodies are divided into plural electrode body sets, the number of the packaging films is plural, one electrode body set is packaged in each of the packaging films to form an electrode body assembly, and the electrode body assemblies are connected in series.

[0025] In some embodiments of the present application, the air pressure between the metal case and the packaging film is P1, the air pressure inside the packaging film is P2, the relationship between P1 and P2 satisfies P1>P2, and the range of P1 / P2 is 0.05 to 0.85.

[0026] In some embodiments of the present application, the value range of P1 is from -100 Kpa to -5 Kpa, and the value range of P2 is from -100 Kpa to -20 Kpa.

[0027] In some embodiments of the present application, the value of P1 ranges from -75 Kpa to -20 Kpa.

[0028] In some embodiments of the present application, the packaging film includes a laminated non-metallic outer film and a non-metallic inner film, the outer film is located between the metal case and the inner film, the melting point of the outer film is higher than the melting point of the inner film, and the melting point difference between the outer film and the inner film is in the range of 30°C to 80°C.

[0029] In some embodiments of the present application, the material of the outer layer film is a combination of one or more of polyethylene terephthalate, polyamide, and polypropylene, and the material of the inner layer film is a combination of one or more of polypropylene, polyethylene, and polyethylene terephthalate.

[0030] In some embodiments of the present application, the outer layer film is adhered to the inner layer film.

[0031] In some embodiments of the present application, the bonding adhesive is a polyolefin adhesive.

[0032] In some embodiments of the present application, the packaging film is an aluminum laminate film.

[0033] In some embodiments of the present application, the metal case is provided with an air vent hole, and a sealing member is provided inside the air vent hole.

[0034] In some embodiments of the present application, the battery pack further includes a battery pack cover and a tray, the battery pack cover and the tray are connected to form a battery accommodating cavity, the battery string is positioned in the battery accommodating cavity, the tray includes a support member, a support area is formed in the metal case, and the single battery is abutted against the support member by the support area and supported by the support member.

[0035] In some embodiments of the present application, the tray includes side beams that are support members, and both ends of the unit cells along the second direction are supported by the side beams.

[0036] An electric vehicle according to a second aspect of the present application includes the battery pack according to any one of the above embodiments.

[0037] Compared with the prior art, the present invention has the following advantageous effects: The battery pack of the present invention includes a plurality of cells, each of which includes a metal case and an electrode assembly packaged in the metal case, and the air pressure inside the metal case is made lower than the air pressure outside the metal case, i.e., the inside of the metal case is made to be in a negative pressure state, thereby bringing the battery case as close as possible to the internal electrode assembly, reducing the internal gap, preventing the electrode assembly from moving within the metal case, and preventing the electrode assemblies from displacing each other relative to each other, thereby reducing the occurrence of situations such as damage to the current collector, wrinkled separator, and detachment of the active material layer, thereby improving the mechanical strength of the entire battery, extending the service life of the battery, and improving the safety performance of the battery. At the same time, this method allows multiple electrode assemblies to be packaged within a single metal case, making it easier to manufacture long cells, and therefore the solution of the present application makes it easy to manufacture long, strong cells. As a result, when installing cells within a battery pack case, the need for supporting structures such as horizontal and vertical beams within the battery pack can be reduced, and the cells themselves can be used as supports to directly install the batteries in the battery pack case, thereby saving internal space in the battery pack, improving the volume utilization rate of the battery pack, and helping to reduce the weight of the battery pack. On the other hand, a certain gap is left between the cells based on the thickness of the cells, and this gap not only functions as a heat dissipation path for the battery pack, improving the heat dissipation efficiency of the battery pack, but also provides a buffer space in the event of cell expansion, significantly improving the safety performance of the battery pack.

[0038] Additional aspects and advantages of the present application will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the present application. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a schematic diagram of a cell according to an embodiment of the present application; [Figure 2] FIG. 2 is a schematic diagram of electrode assembly connections within a cell according to an embodiment of the present application. [Figure 3]1 is a schematic configuration diagram of a battery string according to an embodiment of the present application; [Figure 4] 1 is a schematic diagram illustrating the configuration inside a metal case of a cell in which packaging films for a plurality of electrode bodies are integrated, according to one embodiment of the present application. FIG. [Figure 5] 1 is a schematic diagram of the interior of a metal case of a cell in which a package film is separate, according to one embodiment of the present application. [Figure 6] FIG. 2 is a schematic diagram illustrating a depression in the surface of a metal case of a battery according to an embodiment of the present application. [Figure 7] 1 is a schematic configuration diagram of a battery pack according to an embodiment of the present application; [Figure 8] 1 is a schematic diagram illustrating the relationship between an electric vehicle and a battery pack according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, the embodiments of the present application will be described in detail, and examples of the embodiments are shown in the drawings, and the same or similar reference numerals throughout indicate the same or similar parts or parts having the same or similar functions. The embodiments described below with reference to the drawings are merely illustrative and are intended to interpret the present application, but should not be understood as limiting the present application.

[0041] In the description of this application, the orientations or positional relationships indicated by terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" are based on the orientations or positional relationships shown in the drawings, and are intended merely to facilitate and simplify the description of this application. They do not indicate or suggest that the devices or parts shown must have a specific orientation, be configured, and operate in a specific orientation, and therefore should not be understood as limiting this application.

[0042] As shown in Figures 1 to 8, a battery pack 200 according to the present application includes a battery string 201 including a plurality of cells 100, the thickness of which extends along a first direction A, and the plurality of cells 100 are sequentially arranged along the first direction A to form the battery string 201; in other words, the plurality of cells 100 are arranged in the battery string 201 along the thickness direction of the battery.

[0043] The number of battery strings 201 may be one or more, and the number of cells 100 in each battery string 201 may be one or more. In actual production, the number of cells 100 can be set according to demand, and the number of battery strings 201 can also be set according to demand, and this application does not specifically limit this.

[0044] There is a gap between at least two adjacent cells 100, and the ratio of the gap to the thickness of the cell 100 is in the range of 0.001 to 0.15.

[0045] The gap between two adjacent cells 100 changes as the operating time of the cells 100 increases, but even during or after operation or before the cells 100 are shipped, as long as the ratio range of the gap to the thickness between the cells 100 is within the range limited by this application, all of these are within the scope of protection of this application.

[0046] The areas of the two opposing surfaces of the cells 100 in the thickness direction are maximum, and the cells 100 are arranged along the thickness direction; in other words, the cells 100 are arranged in order with their larger surfaces facing each other, and the surfaces with larger areas are more likely to expand, and a certain gap left between the cells 100 can serve as a buffer space when the cells 100 expand.

[0047] The expansion of the cells 100 is related to the thickness of the cells 100, and the thicker the battery, the more likely the cells 100 are to expand. In the present application, the ratio of the gap between the cells 100 to the thickness of the cells 100 is limited to 0.001 to 0.15, which not only makes full use of the space in the battery pack 200 and improves the utilization rate of the battery pack 200, but also provides an excellent buffering effect against the expansion of the cells 100.

[0048] Furthermore, since the cells 100 generate heat when they expand, certain gaps are left between the cells 100, and these gaps can further function as heat dissipation passages, for example, air ducts. Since the larger area of ​​the cells 100 has a higher heat dissipation effect, the heat dissipation efficiency of the battery pack 200 can be improved, and the safety performance of the battery pack 200 can be improved.

[0049] In the above solution, the gaps between the cells 100 can be understood as simply leaving a certain space without any structural members being installed between the cells 100, and further, can be understood as other structural members being installed on the cells 100, separating the cells 100 from each other by those structural members.

[0050] It should be understood that when a structural member is provided between the cells 100, the gap between the cells 100 is not the distance between the structural member and the cells 100, but the distance between the cells 100 on either side of the structural member.

[0051] A certain gap may be left between the structural member and the cells 100 on both sides of the structural member, or they may be in direct contact with each other. If the structural member is in direct contact with the cells 100 on both sides, the structural member must have a certain flexibility so that it can act as a buffer when the cells 100 expand. Examples of structural members include, but are not limited to, aerogel, thermally conductive structural adhesive, or insulating cotton.

[0052] In this application, when there are multiple battery strings 201, the gap should refer to the gap between two adjacent cells 100 in the same battery string 201, not the gap between two adjacent batteries in different battery strings 201. Also, in the same battery string 201, a certain gap may be left between all two adjacent batteries, or a certain gap may be left between some two adjacent batteries.

[0053] In this embodiment, at least one cell 100 includes a metal case 101 and an electrode assembly 102 packaged in the metal case 101. The air pressure inside the metal case 101 is lower than the air pressure outside the metal case 101, that is, the inside of the metal case 101 is in a negative pressure state.

[0054] In this application, "pressure" is an abbreviation for atmospheric pressure. It refers to the pressure of a gas acting per unit area, i.e., equal to the weight of a vertical column of air extending upward into the upper atmosphere, per unit area.

[0055] In this embodiment, the metal case 101 has high strength and good heat dissipation effect, and the metal case 101 includes, but is not limited to, an aluminum case or a steel case.

[0056] If the gap between the metal case 101 and the electrode assembly 102 is large, when the battery 100 vibrates or shakes, the electrode assembly 102 is likely to move within the metal case 101, and the electrode assemblies 102 are also likely to displace relative to each other. This can damage the electrode assembly 102, for example, causing the current collector to break, the separator to wrinkle, and the active material layer on the electrode plate to fall off, reducing the stability of the battery 100 and potentially causing safety issues such as a short circuit between the positive and negative electrodes. In the present application, by placing the metal case 101 in a specific negative pressure state, the metal case 101 is caused to dent or deform under the action of atmospheric pressure, thereby reducing the gap between the metal case 101 and the electrode assembly 102, thereby reducing the space in which the electrode assemblies 102 move or displace relative to each other. This further reduces the movement of the electrode assemblies 102 and the relative displacement between the electrode assemblies 102, thereby improving the stability, strength, and safety performance of the battery 100.

[0057] In the embodiments of the present application, the largest surface of each cell 100 faces the largest surface of an adjacent cell 100. That is, when multiple cells 100 are arranged in sequence along the thickness direction, the cells 100 are arranged so that their "large surfaces face each other." In one embodiment, the interior of the metal case 101 is under negative pressure, and the largest surface of the metal case 101 is likely to be recessed inward. This recess may be a recess formed on the surface of the metal case 101 when a vacuum is drawn into the metal case 101 of the cell 100. During normal use of a battery, the battery generally expands due to the expansion of the material itself, gas generation from the electrolyte, and the like, and it is known that the area of ​​greatest expansion and deformation is usually located on the large surface of the battery. Using this technology, when the battery is in its initial state, the large surface is formed to be slightly recessed inward by drawing a vacuum, which effectively relieves the pressure between the cells after battery expansion and improves the service life, safety, and the like of the battery and the entire system.

[0058] Furthermore, by using the method of the present application, multiple electrode bodies 102 can be packaged in the metal case 101, making it easier to manufacture long cells 100. Therefore, the solution of the present application makes it easy to manufacture long, strong cells 100. As a result, when installing the cells 100 in the case of the battery pack 200, there is no need to provide support structures such as horizontal and vertical beams, and the cells 100 can be directly installed in the case of the battery pack 200 using the metal case 101 of the cells 100 itself as a support. This saves the internal space of the battery pack 200, improves the volume utilization rate of the battery pack 200, and helps reduce the weight of the battery pack 200.

[0059] The number of electrode bodies 102 packaged in the metal case 101 may be one or more, and the multiple electrode bodies 102 may be connected to each other in series or in parallel.

[0060] The electrode assembly 102 includes a positive electrode plate, a separator, and a negative electrode boardThe electrode assembly further includes an electrolyte.

[0061] In some embodiments, the air pressure inside the metal case 101 is -100Kpa to -5Kpa, and further, the air pressure inside the metal case is -90Kpa to -20Kpa. Of course, those skilled in the art can set the air pressure inside the metal case 101 according to actual needs.

[0062] In some embodiments, the thickness of the metal case 101 is 0.05 mm to 1 mm.

[0063] If the metal case 101 is too thick, not only will it increase the weight of the battery 100 and reduce the capacity of the battery 100, but if the metal case 101 is too thick, the metal will be difficult to dent or deform toward the electrode body 102 due to atmospheric pressure, which will not reduce the gap between the metal case 101 and the electrode body 102 and will not effectively serve to position the electrode body 102. Furthermore, if the metal case 101 is too thick, the cost of venting air will increase, which will increase manufacturing costs.

[0064] By limiting the thickness of the metal case 101 to the above range, the present application not only ensures the strength of the metal case 101, but also does not reduce the capacity of the single battery 100. Furthermore, under negative pressure, the metal case 101 is more likely to deform, and by reducing the gap between the metal case 101 and the electrode body 102, movement of the electrode body 102 inside the metal case 101 and relative displacement between the electrode bodies 102 are reduced.

[0065] In some embodiments of the present application, the metal case 101 includes a case body 1012 having an opening and an end cover 1011, and the end covers 1011 are each sealingly connected to the openings of the case body 1012 to form a sealed storage chamber together with the case body, and the electrode body 102 is located within the storage chamber.

[0066] The gap between the two cells 100 includes a first gap S, which is the minimum distance along the first direction A between the two end covers 1011 of two adjacent cells 100, the thickness of the cell 100 is the dimension of the end cover 1011 along the first direction A, and the ratio range of the first gap to the thickness of the cell 100 is 0.005 to 0.1.

[0067] In the above embodiment, the end cover 1011 has high strength and is therefore less likely to expand relative to the case body 1012. After the cells 100 have been operating for a certain period of time, a chemical reaction occurs inside the cells 100, causing the cells 100 to expand and press against adjacent cells 100. Even if the first gap S changes (e.g., gradually increases), the degree of change is small and can be ignored, or even if it does change, the ratio of the first gap S to the thickness of the cells 100 still satisfies the above range. In the above embodiment, when end covers 1011 are provided on both ends of the case body 1012 and the cells 100 are arranged in a battery string 201 along the thickness direction, the gap between two cells 100 refers to the minimum distance between two end covers 1011 located at the same end of the battery string 201, not the distance between two end covers 1011 located at different ends of the cells 100.

[0068] In the above embodiment, the case body 1012 may be open at one end, with the first electrode 1021 and the second electrode 1022 being drawn out from the same side, or the case body 1012 may be open at both ends, with the first electrode 1021 and the second electrode 1022 being drawn out from end covers 1011 located at both ends of the case body 1012, as shown in Figure 2.

[0069] In some embodiments of the present application, the metal case 101 includes a case body 1012 having an opening and an end cover 1011, the end cover 1011 is sealingly connected to the opening of the case body 1012 to form a sealed storage chamber together with the case body, and the electrode assembly 102 is located in the storage chamber. The case body 1012 has two opposing first surfaces along a first direction A, the gap between two adjacent cells 100 includes a second gap, the second gap is the minimum distance between the two opposing first surfaces of the case body 1012 of the two adjacent cells 100, and the thickness of the cell 100 is the dimension of the end cover 1011 along the first direction.

[0070] The second gap of the cell 100 before use is larger than the second gap of the cell 100 after use.

[0071] The "before use" can be understood as the state before shipping the cell 100 after assembly or after shipping but before starting to supply power to the outside, and the "after use" can be understood as the state after the cell 100 has supplied power to the outside. For example, when the battery pack 200 is assembled into an electric vehicle 300, the state before use can be understood as the state of a new vehicle, and the state after use can be understood as the state after the vehicle has traveled a certain distance.

[0072] In this embodiment, the second gap should refer to the minimum distance between the two opposing first surfaces of two adjacent cells 100, which gradually becomes smaller as the battery usage time increases, mainly because the distance between the two adjacent large surfaces gradually becomes smaller after the cells expand.

[0073] In some embodiments of the present application, the metal case 101 has two opposing first surfaces along the first direction A, at least one of which is recessed into the metal case 101. FIG. 6 shows an inner recessed region 1013 of the metal case. The recessed metal case 101 provides a localized clamping effect on the internal electrode assembly 102, effectively preventing movement of the internal electrode assembly 102 during battery manufacture and use, thereby improving battery safety. Preferably, both first surfaces are recessed into the metal case 101, thereby enhancing the positioning effect of the metal case 101 on the electrode assembly 102. In one example, the metal case 101 is pressed against the outer surface of the electrode assembly 102 along the first direction A to clamp the electrode assembly 102 and prevent movement of the electrode assembly 102.

[0074] In some embodiments, before evacuating the metal case 101, a gap is provided between the electrode body 102 and the inner surface of the metal case 101, and the gap allows the electrode body 102 to be attached to the metal case. 101 After air is evacuated from the metal case 101, the metal case 101 is pressed against the outer surface of the electrode body 102 along the first direction A to clamp the electrode body 102, thereby reducing the space in which the electrode body 102 moves inside the metal case 101 and improving the safety performance of the single battery 100.

[0075] In some embodiments of the present application, the number of electrode bodies 102 packaged in the metal case 101 is multiple, and the multiple electrode bodies 102 are divided into multiple electrode body sets 1023, and the electrode body sets 1023 are connected in series.

[0076] In other words, a plurality of electrode assembly sets 1023 are connected in series within the metal case 101, and each electrode assembly set 1023 includes at least one electrode assembly 102, thereby improving the capacity of the cell 100 and reducing the manufacturing cost of the cell 100. Figures 2, 4, and 5 only show that the electrode assembly set 1023 includes one electrode assembly 102.

[0077] In the embodiment of the present application, each electrode assembly set 1023 has a first electrode 1021 and a second electrode 1022 that draw current, and the multiple electrode assembly sets 1023 are connected in series, i.e., the first electrode 1021 of one electrode assembly set 1023 is electrically connected to the second electrode 1022 of an adjacent electrode assembly set 1023. In the present technology, by using a format in which the electrode assemblies 102 are connected in series, it is possible to improve the capacity and voltage of a single battery and reduce the manufacturing process and costs.

[0078] The arrangement direction of the multiple electrode assembly sets 1023 is a second direction B perpendicular to the first direction A (i.e., the thickness direction of the cell 100), and the length of the cell 100 extends along the second direction B. That is, the multiple electrode assembly sets 1023 are arranged in order along the length of the cell 100, and the length of the electrode assembly sets 1023 also extends along the second direction B, and the first electrode 1021 and the second electrode 1022 of each electrode assembly set 1023 are located on either side of the electrode assembly set 1023 along the second direction B. That is, the multiple electrode assembly sets 1023 are arranged in a "head-to-head" manner, which makes it easy to connect the electrode assembly sets 1023 two by two in series, resulting in a simple connection structure. Furthermore, this arrangement makes it easy to manufacture long cells 100.

[0079] The battery length is 400 mm to 2500 mm (millimeters), and may be, for example, 500 mm, 1000 mm, or 1500 mm. Compared to the conventional method of providing only one electrode assembly 102, providing multiple electrode assembly sets 1023 within the battery makes it easier to manufacture long batteries. In conventional cases, as the length of the cell 100 increases, the length of the internal copper-aluminum foil used as a current collector correspondingly increases, significantly increasing the battery's internal resistance and making it impossible to meet the increasingly high power and rapid charging requirements. For a given battery length, this embodiment significantly reduces the battery's internal resistance, avoiding problems such as battery overheating during high power output and rapid charging.

[0080] In some embodiments of the present application, the electrode assembly sets 1023 are connected in series to form an electrode assembly string, and of two electrode assembly sets 1023 located at the head and tail ends of the electrode assembly string, the first electrode 1021 of one electrode assembly set 1023 and the second electrode 1022 of the other electrode assembly set 1023 are respectively drawn out from both ends of the metal case 101 along the second direction B. That is, the current of the cell 100 is drawn out from both ends of the metal case 101, and when the cell 100 is long, drawing out the current from both ends can reduce the current flow path and the internal resistance of the battery.

[0081] In some embodiments of the present application, the thickness of the cell 100 is greater than 10 mm, and in other embodiments, the thickness of the cell 100 is between 13 and 75 mm.

[0082] In some embodiments of the present application, a packaging film 103 is further provided between the metal case 101 and the electrode body 102 , and the electrode body 102 is packaged in the packaging film 103 .

[0083] That is, the electrode assembly 102 is first packaged in the packaging film 103, and then the metal case 101 is fitted onto the outside of the packaging film 103, thereby achieving secondary packaging for the electrode assembly 102 and improving the sealing performance of the cell 100. It should be understood that an electrolyte solution is also injected into the packaging film 103. Therefore, this method further avoids contact between the electrolyte solution and the metal case 101, and can prevent corrosion of the metal case 101 or decomposition of the electrolyte solution.

[0084] In some embodiments, the number of electrode bodies 102 is plural, and the plural electrode bodies 102 are divided into plural electrode body sets 1023, and the electrode body sets 1023 are connected in series. The plural electrode body sets 1023 connected in series are packaged in the same packaging film 103, and each electrode body set 1023 includes an electrode body set body 1024 and a first electrode 1021 and a second electrode 1022 electrically connected to the electrode body set body 1024 to draw current. 1023 The connection point between the first electrode 1021 of one of the electrode body sets 1024 and the second electrode 1022 of the other electrode body set is located inside the package film 103.

[0085] In other words, the package film 103 is integrally provided, multiple electrode bodies 102 are packaged within the same package film 103, the electrode bodies 102 are divided into multiple electrode body sets 1023, each electrode body set 1023 includes at least one electrode body 102, the multiple electrode bodies 102 in the same electrode body set 1023 are connected in parallel, and the electrode body sets 1023 are connected in series, thereby improving the capacity of the battery and reducing manufacturing costs.

[0086] In this embodiment, the series connection method may be such that adjacent electrode assembly sets 1023 are connected in series. As a specific method to be realized, the first electrode 1021 and the second electrode 1022 on the adjacent electrode assembly sets 1023 may be directly connected, or may be electrically connected by an additional conductive member. Generally, each of the electrode assembly sets 1023 includes a first electrode 1021 and a second electrode 1022 that both draw current. When the electrode assembly set 1023 includes only one electrode assembly 102, the first electrode 1021 and the second electrode 1022 may be the positive electrode tab and the negative electrode tab of the electrode assembly 102, respectively, or may be the negative electrode tab and the positive electrode tab of the electrode assembly 102, respectively. When multiple electrode assemblies 102 are included, the lead members of the first electrode 1021 and the second electrode 1022 may be electrode lead wires, or may be the first electrode 1021 and a second electrode 1022One of the electrodes may be a lead-out member formed by compound welding the positive electrode tabs of multiple electrode bodies 102, and the other electrode may be a lead-out member formed by compound welding the negative electrode tabs of multiple electrode bodies 102.

[0087] In this application, the terms "first" and "second" in the terms "first electrode 1021" and "second electrode 1022" are used only to distinguish the names and do not limit the number; for example, the term "first electrode 1021" may include one first electrode 1021 or multiple first electrodes 1021.

[0088] When multiple electrode bodies 102 are contained within the metal case 101, the negative pressure within the metal case 101 can effectively prevent the multiple electrode bodies 102 from moving within the metal case 101, thereby improving the safety performance of the single battery 100.

[0089] In the above embodiment, a package section 1031 is formed at a relative position between the package film 103 and the first electrode 1021 and / or second electrode 1022 to separate two adjacent electrode assembly sets 1024, and at least one of the first electrode 1021 of one electrode assembly set 1023 and the second electrode 1022 of the other electrode assembly set 1023 is located within the package section 1031. The package section 1031 separates the multiple electrode assembly sets 1023, preventing the electrolytes in the multiple electrode assembly sets 1023 from circulating with each other, preventing the multiple electrode assembly sets 1023 from affecting each other, and preventing the electrolytes in the multiple electrode assembly sets 1023 from decomposing due to excessive potential differences, thereby ensuring the safety and service life of the battery.

[0090] The packaging part 1031 may have various embodiments, for example, the packaging part 1031 may be formed by fastening the packaging film 103 using a cable tie, or the packaging film 103 may be directly heat-sealed and connected to form the packaging part 1031. The specific form of the packaging part 1031 is not particularly limited.

[0091] In such an implementation method, a plurality of electrode body sets 1023 can share the same packaging film 103, and in this case, a packaging section 1031 is provided between each electrode body set 1023, and the packaging section 1031 may be formed by heat-sealing and connecting the packaging films 103 between the electrode body sets 1023. Specifically, the electrode body set 1023 has a first electrode 1021 and a second electrode 1022. Before packaging the electrode body sets 1023, first, a plurality of electrode body sets 1023 are connected in series, and then the series-connected electrode body sets 1023 are wrapped using one package film 103; for example, the series-connected electrode body sets 1023 are placed in a portion of the package film 103, and then another portion of the package film 103 is folded in half toward the electrode body sets 1023, and then the package film 103 in the two portions is heat-sealed and sealed using a heat sealing process, thereby packaging the series-connected electrode body sets 1023 within the same package film 103, and the package film 103 in the two upper and lower portions located between the electrode body sets 1023 is heat-sealed and extruded to form a single unit, thereby forming a separator that separates the electrode body sets 1023 between the electrode body sets 1023.

[0092] In some embodiments of the present application, the number of electrode bodies 102 is plural, the plural electrode bodies 102 are divided into plural electrode body sets 1023, the number of packaging films 103 is plural, each electrode body set 1023 includes at least one electrode body 102, one electrode body set 1023 is packaged in each packaging film 103 to form an electrode body assembly, and the electrode body assemblies are connected in series.

[0093] In other words, the number of packaging films 103 and the number of electrode body sets 1023 correspond one to one, and each electrode body set 1023 is packaged individually in one packaging film 103. In such an embodiment, after the manufacture of multiple electrode body sets 1023 is completed, one packaging film 103 can be individually fitted to the outside of each electrode body set 1023, and then the electrode body assemblies can be connected in series.

[0094] The packaging films 103 of the multiple electrode assembly sets 1023 are independent of one another, that is, each electrode assembly set 1023 is packaged using a single packaging film 103, and at this time, the first electrode 1021 and second electrode 1022 of the electrode assembly set 1023 are respectively drawn out from both ends of the electrode assembly set 1023 along the second direction B. After each electrode assembly set 1023 is packaged in the packaging film 103, the drawn out first electrode 1021 and second electrode 1022 are connected in series.

[0095] In the embodiment of the present application, the air pressure between the metal case 101 and the package film 103 is P1, the air pressure inside the package film 103 is P2, the relationship between P1 and P2 satisfies P1>P2, and the range of P1 / P2 is 0.05 to 0.85.

[0096] That is, the inside of the package film 103 may be in a negative pressure state. This helps to bring the package film 103 and the electrode body 102 into close contact with each other, and increases the strength of the unit cell 100.

[0097] In some specific embodiments, the value range of P1 is -100 Kpa to -5 Kpa, and the value range of P2 is -100 Kpa to -20 Kpa. In one example, the value range of P1 is -75 Kpa to -20 Kpa.

[0098] With P1, P2, and P1 / P2 limited within the above ranges, the electrode assembly 102 in this technology uses a secondary sealing mode, in which the electrode assembly 102 is first packaged in a packaging film 103, and the air pressure between the metal case 101 and the packaging film 103 should be selected to be greater than the air pressure within the packaging film 103, in order to avoid damage to the packaging film 103 due to the packaging film 103 bulging outward due to excessive internal air pressure. Furthermore, numerous experiments have verified that when P1 / P2 is within the above range, the reliability of the secondary sealing of the battery is well guaranteed, the interface between the battery plates is guaranteed, the gap between the plates is reduced, and lithium ions are better conducted.

[0099] In the present embodiment, the packaging film 103 includes a laminated outer layer film and an inner layer film. The inner layer film is wrapped around the outer periphery of the electrode body 102, and the outer layer film is wrapped around the inner layer film, i.e., the inner layer film is located between the outer layer film and the electrode body 102.

[0100] The inner layer film may be made of a material having high chemical stability and resistance to corrosion by an electrolyte, such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), or a combination of two or more of the above materials.

[0101] The outer layer film is a protective layer that can be used to prevent the penetration of air, particularly water vapor, oxygen, etc., and its material may be, for example, polyethylene terephthalate, polyamide, or polypropylene, or a combination of two or more of the above materials.

[0102] In the present embodiment, the melting point of the outer layer film is higher than that of the inner layer film, so that when heat-sealing is performed, the outer layer film does not melt, but the inner layer film melts in a timely manner, ensuring excellent sealing. In one embodiment, the difference in melting point between the outer layer film and the inner layer film may be between 30°C and 80°C, for example, the difference in melting point between the two may be 50°C or 70°C, and the specific materials may be selected according to actual needs.

[0103] In the present embodiment, the non-metallic outer film and the non-metallic inner film are bonded together with an adhesive. The specific adhesive can be selected according to the properties of the non-metallic outer film and the non-metallic inner film. For example, when PP and PET films are bonded together, which have low compatibility and are easy to layer, a polyolefin adhesive is preferably used to bond them together to form a composite film.

[0104] In this embodiment, a packaging film 103 is formed using a two-layer non-metallic film to package the electrode assembly 102. The use of the non-metallic packaging film 103 increases the tensile strength and breaking elongation, reducing the limitations on the thickness of the cell 100, resulting in a thicker cell 100. The thickness of the cell 100 in this embodiment has a wide range of extensibility, for example, greater than 10 mm, and may be in the range of 13 mm to 75 mm.

[0105] In some embodiments of the present application, the packaging film may be an aluminum laminate film.

[0106] In some embodiments of the present application, an air vent hole is provided in the metal case 101, and air is vented from inside the metal case 101 through the air vent hole, thereby creating a negative pressure state inside the metal case 101. After the air vent process, it is necessary to seal the air vent hole, and in the examples of the present application, the air vent hole is closed by providing a sealing member inside the air vent hole.

[0107] SealingThe member may be a plug or rubber stopper, or may be any other structural member, and the present application is not particularly limited thereto.

[0108] In the present embodiment, the battery pack 200 further includes a battery pack cover (not shown) and a tray 202. The battery pack cover and the tray 202 are sealed together to form a housing cavity, and the battery string 201 is housed in the housing cavity. The tray 202 includes a support member, and a support region is formed in the metal case 101 of the cell 100. The cell 100 abuts against the support member via the support region and is supported by the support member.

[0109] In one embodiment, the tray 202 includes side beams, and both ends of the unit cell 100 along the second direction B are supported by the side beams.

[0110] Therefore, in the present application, the battery cells 100 can be directly supported by the strength of the battery cells 100 themselves and fixed directly to the tray 202, and there is no need to support the battery cells 100 by adding horizontal or vertical beams to the tray 202, thereby improving the space utilization rate inside the battery pack 200.

[0111] In one embodiment of the present application, the cell 100 is a lithium ion battery.

[0112] An electric vehicle 300 according to another embodiment of the present application includes the battery pack 200. The electric vehicle 300 according to the present application has a long driving range and low cost.

[0113] In the description of this application, unless otherwise clearly specified or limited, the terms "attached," "coupled," and "connected" should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, or internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in this application according to specific circumstances.

[0114] In the description herein, a description that refers to the terms "embodiment," "specific embodiment," "example," etc. means that the specific features, structures, materials, or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the description herein, the exemplary expressions of the terms are not necessarily limited to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined as appropriate in any one or more embodiments or examples.

[0115] Although the embodiments of the present application have been illustrated and described, as will be understood by those skilled in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is limited by the claims and their equivalents. [Explanation of symbols]

[0116] 100 D cells 101 Metal Case 1011 End cover 1012 Case body 1013 inner recess area, 102 Electrode body 1021 First electrode 1022 Second electrode 1023 Electrode Set 1024 Electrode set main body 103 Packaging Film 1031 Packaging Department 200 battery packs 201 Battery String 202 Tray 300 electric vehicles D Cell thickness L length of a single cell S First gap A. First direction B Second Direction

Claims

1. The battery includes a battery string including a plurality of unit cells, each unit cell including one electrode assembly and being a rectangular cell, the electrode assembly including a positive electrode plate, a separator, a negative electrode plate, and an electrolyte; a plurality of the unit cells are arranged in order along a second direction to form the battery string; a plurality of the battery strings are arranged along a first direction perpendicular to the second direction; Each battery string includes a metal case and an electrode assembly packaged in the metal case, and the air pressure inside the metal case is lower than the air pressure outside the metal case. There is a gap between the opposing flat surfaces of two adjacent battery rows, and the ratio of the gap to the thickness of the battery cell is in the range of 0.001 to 0.15; A battery pack, characterized in that a package film is further provided between the metal case and the electrode body, and one or more of the electrode bodies are packaged in the package film.

2. 2. The battery pack according to claim 1, wherein the pressure inside the metal case ranges from -100 Kpa to -5 Kpa.

3. 3. The battery pack according to claim 2, wherein the pressure inside the metal case ranges from -90 Kpa to -20 Kpa.

4. 4. The battery pack according to claim 1, wherein the metal case has a thickness ranging from 0.05 mm to 1 mm.

5. the metal case includes a case body having an opening and an end cover, the end cover is sealingly connected to the opening of the case body to form a sealed storage chamber together with the case body, and the electrode body is located within the storage chamber; The battery pack according to any one of claims 1 to 4, characterized in that the gap between two adjacent battery rows includes a first gap, the first gap being the minimum distance along a first direction between two end covers of two adjacent unit cells, the thickness of the unit cells being a dimension of the end cover along the first direction, and the range of the value of the ratio of the first gap to the thickness of the unit cells being 0.005 to 0.

1.

6. the metal case includes a case body having an opening and an end cover, the end cover is sealingly connected to the opening of the case body to form a sealed storage chamber together with the case body, and the electrode body is located within the storage chamber; the case body has two opposing first surfaces along the first direction, 6. The battery pack according to claim 1, wherein a gap between two adjacent battery rows includes a second gap, the second gap being a minimum distance between two of the first surfaces of the case bodies of the two adjacent unit cells that face each other, and a thickness of the unit cell is a dimension of the end cover along the first direction.

7. 7. The battery pack according to claim 1, wherein the second gap before the unit cells are used is larger than the second gap after the unit cells are used.

8. 7. The battery pack according to claim 6, wherein the metal case has two opposing first surfaces along the first direction, and at least one of the first surfaces is recessed inside the metal case.

9. 9. The battery pack according to claim 8, wherein the two first surfaces are both recessed into the metal case, and the metal case is pressed against the outer surface of the electrode body along the first direction to sandwich the electrode body.

10. 10. The battery pack according to claim 9, wherein before air is evacuated from the metal case, a gap is provided between the electrode body and the inner surface of the metal case, and after air is evacuated from the metal case, the metal case is pressed against the outer surface of the electrode body along a first direction to sandwich the electrode body.

11. The battery pack according to any one of claims 1 to 10, wherein the number of electrode bodies packaged in the metal case is plural, the plural electrode bodies are divided into plural electrode body sets, and the electrode body sets are connected in series.

12. 12. The battery pack of claim 11, wherein the length of the cell extends along a second direction and is 400 mm to 2500 mm, the plurality of electrode body sets are arranged along the second direction, the length of the electrode body set extends along the second direction, the electrode body set includes a first electrode and a second electrode that draw current, and the first electrode and the second electrode are located on either side of the electrode body set along the second direction.

13. 13. The battery pack according to claim 12, wherein the electrode sets are connected in series to form an electrode string, and first electrodes of one of the two electrode sets are disposed at a leading end and a trailing end of the electrode string, and second electrodes of the other electrode set are drawn out from both ends of the metal case along the second direction.

14. The battery pack according to any one of claims 1 to 13, wherein the thickness D of the unit cell is greater than 10 mm.

15. 15. The battery pack according to claim 14, wherein the thickness of the unit cell is 13 mm to 75 mm.

16. the number of the electrode bodies is plural, the plural electrode bodies are divided into plural electrode body sets, the number of the package films is one, the electrode body sets are connected in series, and the plural serially connected electrode body sets are packaged in the same package film; 2. The battery pack according to claim 1, wherein the electrode set includes an electrode set body and a first electrode and a second electrode for drawing current, and a connection point between the first electrode of one of the two electrode sets connected in series and the second electrode of the other electrode set is located within the package film.

17. a package portion is formed on the package film at a position corresponding to the first electrode and / or the second electrode, separating two adjacent electrode body set bodies; 17. The battery pack according to claim 16, wherein at least one of the first electrode of one of the two adjacent electrode sets and the second electrode of the other of the two adjacent electrode sets is located within the package portion.

18. The battery pack according to any one of claims 1 to 17, wherein the number of the electrode bodies is plural, the plural electrode bodies are divided into plural electrode body sets, the number of the packaging films is plural, one electrode body set is packaged in each of the packaging films to form an electrode body assembly, and the electrode body assemblies are connected in series.

19. 2. The battery pack according to claim 1, wherein an air pressure between the metal case and the package film is P1, an air pressure inside the package film is P2, and when P1 and P2 are expressed as pressures relative to atmospheric pressure, the relationship between P1 and P2 satisfies P1 > P2, and the range of P1 / P2 is 0.05 to 0.

85.

20. 20. The battery pack according to claim 19, wherein the value of P1 ranges from -100 Kpa to -5 Kpa, and the value of P2 ranges from -100 Kpa to -20 Kpa.

21. The battery pack according to claim 20, wherein the value of P1 ranges from -75 Kpa to -20 Kpa.

22. The battery pack of any one of claims 11 to 13, characterized in that the package film includes a laminated non-metallic outer film and a non-metallic inner film, the outer film is located between the metal case and the inner film, the melting point of the outer film is higher than the melting point of the inner film, and the melting point difference between the outer film and the inner film is in the range of 30°C to 80°C.

23. 23. The battery pack of claim 22, wherein the material of the outer layer film is one or a combination of two or more of polyethylene terephthalate, polyamide, and polypropylene, and the material of the inner layer film is one or a combination of two or more of polypropylene, polyethylene, and polyethylene terephthalate.

24. 24. The battery pack according to claim 22 or 23, wherein the outer layer film is adhered to the inner layer film.

25. A battery pack as described in claim 24, characterized in that the adhesive that adheres the outer layer film to the inner layer film is a polyolefin-based adhesive.

26. The battery pack according to any one of claims 1 to 25, wherein the package film is an aluminum laminate film.

27. The battery pack according to any one of claims 1 to 26, wherein the metal case is provided with an air vent hole, and a sealing member is provided inside the air vent hole.

28. The battery pack according to any one of claims 1 to 27, further comprising a battery pack cover and a tray, the battery pack cover and the tray being connected to form a battery accommodating cavity, the battery string being positioned within the battery accommodating cavity, the tray including a support member, a support region being formed in the metal case, and the unit cells being supported by the support member by being in contact with the support member via the support region.

29. 29. The battery pack according to claim 28, wherein the tray includes side beams that are support members, and both ends of the unit cells along the second direction are supported by the side beams.

30. An electric vehicle comprising the battery pack according to any one of claims 1 to 29.

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