Battery packs and electric vehicles

Abstract

A battery pack (200) and an electric vehicle, wherein the battery pack (200) includes at least one battery unit (21), the battery unit (21) includes at least one battery string (1006), the battery string (1006) includes one or at least two single cells (100), the potential difference across the battery string (1006) is 60 V or less, and when the battery string (1006) includes at least two single cells (100), the single cells (100) in the battery string (1006) are arranged in order along a first direction, and the first direction is parallel to the direction from the rear to the front of the vehicle.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the priority of Chinese Patent Application No. "202010129989.1" named "Battery Pack and Electric Vehicle" filed by BYD Company Limited on February 28, 2020.

[0002] This application relates to the technical field of vehicle manufacturing, and particularly to battery packs and electric vehicles.

Background Art

[0003] In electric vehicles, due to the limited space of the electric vehicle, the battery pack is generally fixed to the bottom of the vehicle, that is, to the chassis of the vehicle. However, since the bottom of the vehicle is close to the ground, the battery pack attached to the bottom of the vehicle is likely to be impacted during the running of the vehicle, making the single cells in the battery pack prone to short - circuit. In particular, the impact received by the bottom of the vehicle during the running of the vehicle generally extends from the front of the vehicle to the rear of the vehicle, resulting in a series of single cells in the battery pack being short - circuited.

[0004] As the power source of an electric vehicle, the battery pack has a very high energy density. High voltage and high energy density also mean high risk at the same time. When a series of single cells in the battery pack are short - circuited, if there is a high voltage between this series of batteries, it will instantly cause high - voltage breakdown or high - voltage short - circuit of the battery pack, making the battery pack prone to catch fire and explode, and also prone to arc - discharge phenomenon, threatening the safety of the driver and passengers.

Summary of the Invention

[0005] This application aims to solve at least one of the technical problems in the prior art. Therefore, this application provides a battery pack and an electric vehicle, which can relatively reduce the voltage generated by the battery pack when the battery string is short - circuited, prevent the occurrence of high - voltage breakdown or high - voltage short - circuit of the battery pack, and help improve the safety of the battery pack.

[0006] This invention further provides electric vehicles.

[0007] To achieve the above objective, the battery pack for providing electrical energy to a vehicle according to the present invention includes at least one battery unit, the battery unit includes at least one battery array, the battery array includes one or at least two single cells, the potential difference across the battery array is 60V or less, and if the battery array includes at least two single cells, the single cells in the battery array are arranged sequentially along a first direction, the first direction being parallel to the direction from the rear to the front of the vehicle.

[0008] In some examples of this application, the potential difference across the battery array is 45V or less.

[0009] In some examples of this application, the potential difference across the battery array is 20 to 40V.

[0010] In some examples of the present invention, the battery unit includes a plurality of the battery rows, which are arranged sequentially along a second direction, the second direction being the width direction of the vehicle.

[0011] In some examples of this application, the battery arrays are connected in series and / or in parallel.

[0012] In some examples of the present invention, if the battery array includes at least two single cells, the single cells in the battery array are connected in series.

[0013] In some examples of the present invention, the length of the single cell extends along a first direction.

[0014] In some examples of the present application, the single cell includes a first pole and a second pole, and the single cell has two first surfaces located opposite each other along a first direction, wherein the first pole and the second pole are located on the same first surface of the single cell, or on two separate first surfaces of the single cell.

[0015] In some examples of the present application, the single cell includes a first pole and a second pole, the single cell has a second surface facing the top of a vehicle, and the first and second poles are located on the second surface.

[0016] In some examples of this invention, there are multiple battery units, and these battery units are connected in series.

[0017] In some examples of the present invention, a plurality of battery units are arranged in an array to form a battery unit array, the battery unit array includes a plurality of rows of battery unit sets, the plurality of rows of battery unit sets are arranged sequentially along a first direction, and an active safety device is connected between two battery units located in two adjacent rows of battery unit sets and electrically connected to each other.

[0018] In some examples of this application, the active safety device is a relay or a fuse.

[0019] In some examples of the present invention, the ratio range of the length of at least one of the single cells to the length of the vehicle is 0.2 to 0.8.

[0020] In some examples of this application, the length range of the single cell 100 is 600 mm to 2500 mm.

[0021] The electric vehicle relating to this application includes the aforementioned battery pack.

[0022] Compared with the prior art, the beneficial effects of the present application are as follows. The battery pack of the present application includes at least one battery unit, the battery unit includes at least one battery string, the battery string includes one or at least two single cells, the potential difference between both ends of the battery string is 60V or less, and when the battery string includes at least two single cells, the single cells in the battery string are arranged in sequence along a first direction, and the first direction is parallel to the direction from the rear part to the front part of the vehicle. Thereby, by this means, the potential difference between both ends of the battery string formed by the single cells arranged in the direction from the rear part to the front part of the vehicle can be reduced. During the running of the vehicle, even if a series of single cells in this direction are all impacted and short-circuited, since the voltage of this series of single cells itself is relatively small, the influence on the battery pack during short-circuit is also relatively small. Thereby, the voltage generated by the battery pack when the battery string is short-circuited can be relatively reduced, preventing the occurrence of high-voltage breakdown or high-voltage short-circuit of the battery pack, reducing the occurrence probability of ignition and explosion of the battery pack, and also reducing the occurrence of arc discharge phenomenon, which helps to improve the safety of the battery pack.

[0023] Additional aspects and advantages of the present application will be shown in part in the following description, become clear in part in the following description, or be grasped by the implementation of the present application.

Brief Description of Drawings

[0024] [Figure 1] It is a schematic structural diagram of the battery pack according to an embodiment of the present application. [Figure 2] It is a schematic diagram of the influence on the single cells in the battery pack after the bottom of the vehicle in the prior art is impacted by a hard object. [Figure 3] It is another structural diagram of the battery pack according to an embodiment of the present application. [Figure 4] It is still another schematic structural diagram of the battery pack according to an embodiment of the present application. [Figure 5] It is still another schematic structural diagram of the battery pack according to an embodiment of the present application. <000009​This is a schematic structural diagram of a single battery according to an embodiment of the present application. [Figure 7] This is another schematic structural diagram of a battery pack according to an embodiment of the present application. [Figure 8] This is a schematic diagram of the impact on the single battery in the battery pack after the bottom of the vehicle in the embodiment of the present application is impacted by a hard object. [Figure 9] This is a schematic cross-sectional view of a single battery according to an embodiment of the present application. [Figure 10] This is a schematic diagram showing that the electrode body set according to the embodiment of the present application is packaged in a packaging film. [Figure 11] This is another schematic diagram showing that the electrode body set according to the embodiment of the present application is packaged in a packaging film. [Figure 12] This is a schematic diagram showing that a recess is formed on the third surface of the metal case according to the embodiment of the present application.

Mode for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present application will be described in detail. Examples of the above embodiments are shown in the drawings, and the same or similar reference numerals throughout indicate the same or similar components, or components having the same or similar functions. Hereinafter, the embodiments described with reference to the drawings are exemplary only and are merely for interpreting the present application and should not be understood as limiting the present application.

[0026] In the description of the present application, the orientation or positional relationship indicated by terms such as "center", "vertical direction", "horizontal direction", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial direction", "radial direction", "circumferential direction", etc. is based on the orientation or positional relationship shown in the drawings, and is merely for facilitating the description and simplifying the description of the present application, and does not indicate or imply that the indicated device or component must have a specific orientation and be configured and operate in a specific orientation, so it should not be understood as limiting the present application.

[0027] Referring to Figure 1, the battery pack 200 according to the embodiment of the present application is applied to an electric vehicle and can provide power to the electric vehicle, which may be, for example, a passenger car or a bus. The battery pack 200 includes at least one battery unit 21, the battery unit 21 includes at least one battery array 1006, the battery array 1006 includes one or at least two single cells 100, and the potential difference V across the battery array 1006 is 60V or less.

[0028] If the battery array 1006 includes at least two single cells 100, the single cells 100 in the battery array 1006 are arranged sequentially along a first direction AB, which is parallel to the direction from the front to the rear of the vehicle.

[0029] To make it easier to understand, a vehicle generally has three dimensions: length, width, and height. The length of a vehicle is the distance from the rear to the front of the vehicle, the width of a vehicle is the distance between the left and right doors, and the height of a vehicle is the distance from the bottom to the top of the vehicle. For most vehicles, the length of the vehicle is generally the maximum dimension of the vehicle, so the first direction AB may also refer to the direction in which the length of the vehicle extends, i.e., the direction of the maximum dimension of the vehicle.

[0030] In some embodiments, the battery unit 21 may consist of only one battery array 1006, and the battery array 1006 may contain multiple single cells 100, which are arranged sequentially along a first direction AB, i.e., all single cells 100 in the battery unit 21 are arranged sequentially along the first direction. The single cells 100 in the battery array 1006 may be connected in series, for example, adjacent single cells 100 may be connected in series, thereby realizing the series connection of multiple single cells. In this case, the potential difference across the battery array 1006 refers to the potential difference across the series of single cells connected in series.

[0031] In some other embodiments, the battery array 1006 may include only one single cell 100, in which case the potential difference across the battery array 1006 refers to the potential difference across the positive and negative terminals of the single cell 100.

[0032] In conventional battery packs, as shown in Figure 2, many single cells are arranged in the battery pack to maximize battery capacity, and many of these single cells are arranged in the direction from the rear to the front of the vehicle (first direction AB). If the underside of the vehicle is struck by a hard object G while the vehicle is in motion, the impact on the underside of the vehicle generally continues from the front to the rear of the vehicle. As a result, all the single cells arranged from the front to the rear of the vehicle within the battery pack (the shaded area in the figure) are all affected by the impact, deform together, and have the potential to rupture. This can cause a short circuit between many of the single cells, generating a higher voltage in the battery pack, leading to battery ignition and explosion.

[0033] The embodiment of the present invention prevents the potential difference V across the battery array 1006 from exceeding 60V, that is, by reducing the potential difference across the battery array formed by single cells arranged in the direction from the rear to the front of the vehicle, even if all single cells 100 arranged in the battery array 1006 in the direction from the front to the rear of the vehicle are subjected to impact and short-circuit while the vehicle is running, the voltage of the battery array 1006 itself is low, resulting in a low-voltage short circuit. This means that the voltage generated by the battery pack when the battery array 1006 is short-circuited is also relatively low, thereby preventing high-voltage breakdown or high-voltage short-circuit of the battery pack, reducing the probability of ignition and explosion of the battery pack, and reducing the occurrence of arc discharge phenomena. This effectively prevents phenomena such as thermal runaway and heat diffusion between single cells, and helps to improve the safety of the battery pack.

[0034] Furthermore, by ensuring that the potential difference across the battery array 1006 does not exceed 60V, the occurrence of arc discharge can be reduced, and the energy storage capacity of the battery pack can be improved as much as possible.

[0035] Furthermore, the potential difference V across the battery array 1006 is 45V or less. By reducing the potential difference V across the battery array 1006, the impact on the battery pack when the battery array 1006 is short-circuited is further relatively reduced, preventing problems such as the battery pack generating a high voltage and being destroyed when the battery array 1006 is short-circuited, and thus preventing the occurrence of arc discharge. The potential difference V across the battery array 1006 may be 20 to 40V, for example, 40V.

[0036] The inventors of this invention, through extensive arc discharge testing, have found that when maximizing battery capacity, the potential difference across the battery array 1006, formed by all single cells arranged along the vehicle's direction of travel (which can also be understood as the direction from the front to the rear of the vehicle), does not exceed 60V, thereby effectively preventing the battery pack from igniting. The experimental data are shown in the table below. [Table 1]

[0037] As can be seen from the experimental data above, when the potential difference across the battery array 1006 does not exceed 60V, the battery pack will not ignite or emit smoke, and will not only meet the power requirements but will also improve the safety performance of the battery pack.

[0038] The arc discharge test experiment can be conducted using the conventional arc discharge test method, in which the potential difference across the battery array is mainly changed during the experiment, and then the test vehicle is driven to travel on a test road with obstacles, and the ignition or smoke emission of the battery pack is observed.

[0039] Referring to Figure 3, in the embodiment of the present invention, the battery unit 21 includes a plurality of battery rows 1006, the plurality of battery rows 1006 are arranged sequentially along a second direction CD, the second direction CD is the width direction of the vehicle, the potential difference V at both ends of each battery row 1006 is 60V or less, and for example, the potential difference at both ends of each battery row 1006 can be 45V or 50V, etc.

[0040] The number of individual cells 100 in the battery train 1006 is not specifically limited; for example, there may be four or six cells, as long as the potential difference across the battery train 1006 does not exceed 60V.

[0041] The individual cells 100 in the same battery array 1006 are connected in series. The battery arrays 1006 may be connected in parallel, in series, or in a combination of series and parallel connections. For example, adjacent battery arrays 1006 may be connected in series, or two battery arrays 1006 may be connected in parallel first and then connected in series to another battery array 1006. The possibilities are not specifically limited.

[0042] As shown in Figure 4, in the embodiment of the present invention, there are multiple battery units 21, and the multiple battery units 21 are connected in series. Specifically, each battery unit 21 includes a first electrode lead terminal 211 and a second electrode lead terminal 212 for drawing current, and the first electrode lead terminal 211 of one of two adjacent battery units 21 is electrically connected to the second electrode lead terminal 212 of the other battery unit 21, thereby achieving the series connection.

[0043] The multiple battery units 21 are arranged in an array to form a battery unit array, which includes multiple rows of battery unit sets 201, which are arranged sequentially along a first direction AB, and each column of battery unit sets 202 contains multiple battery units arranged sequentially along the first direction AB. As shown in Figure 4, the battery unit array may include only one column of battery unit sets 202, or, as shown in Figure 5, the battery unit array may include multiple columns of battery unit sets 202, which are arranged sequentially along a second direction CD, where two adjacent battery units 21 in the same row of battery unit set 201 are connected in series, and two adjacent rows of battery unit sets 201 are also connected in series, and two adjacent rows of battery unit sets are electrically connected via an active safety device 22.

[0044] An active safety device 22 is connected between two battery units 21 located in two adjacent rows of battery unit sets 201 and electrically connected to each other.

[0045] As shown in Figure 4, since each row of battery unit sets has one battery unit 21, the first electrode lead terminal 211 of one battery unit 21 and the second electrode lead terminal 212 of the other battery unit 21 of two adjacent rows of battery unit sets are electrically connected via an active safety device 22. The active safety device 22 includes, but is not limited to, relays, fuses, or other control switches. The active safety device 22 automatically disconnects the connection between two adjacent rows of battery unit sets if the current between them is too high, and disconnects the electrical connection between two adjacent battery units 21 if the current between them is too high, as in the embodiment of Figure 1.

[0046] If there are short-circuited single cells in multiple battery units 21 in the same row, a high-voltage circuit will inevitably be formed between the battery units 21, increasing the current in the circuit. By providing an active safety device 22 between two adjacent rows of battery unit sets, the connection between the two rows of battery units can be disconnected in the event of a short circuit, further improving the safety of the battery pack.

[0047] Referring to Figure 6 in conjunction with Figure 1, in the embodiment of the present application, the cell 100 is substantially a rectangular parallelepiped, and the length of the cell 100 extends along a first direction AB. The cell 100 includes a first pole 1001 and a second pole 1002, the polarities of the first pole 1001 and the second pole 1002 are opposite, and draw current, for example, the first pole 1001 is the positive pole and the second pole 1002 is the negative pole.

[0048] The single cell 100 has two first surfaces 1003 located opposite each other in a first direction AB, and the first pole 1001 and the second pole 1002 may be located on the same first surface 1003 of the single cell 100, or they may be located on two separate first surfaces 1003.

[0049] In a single battery unit 21, if the battery unit 21 contains multiple single cells 100, and the multiple single cells 100 are arranged to form multiple rows of single cell groups, the multiple rows of single cell groups are arranged sequentially along a second direction CD. In the embodiment of the present application, by extending the length of the single cells 100 along a first direction AB and arranging the multiple single cells along a second direction CD, the number of single cells damaged when the bottom of the vehicle collides can be reduced. As shown in Figure 8, when multiple single cells are arranged along a second direction CD, and the bottom of the vehicle is struck by a hard object G while the vehicle is in motion, the number of single cells affected by the collision with the foreign object (single cells shown in the shaded area of ​​the figure) can be reduced, thus avoiding damage to all single cells in the battery pack. Therefore, this embodiment can further improve the safety of the battery pack.

[0050] In other embodiments, as shown in Figure 7 in conjunction with Figure 6, the first pole 1001 and the second pole 1002 of the single cell 100 may further be provided on other surfaces of the single cell. Specifically, the single cell 100 has a second surface 1004 facing the top of the vehicle, and the first pole 1001 and the second pole 1002 are located on the second surface 1004.

[0051] The single cell 100 has two second surfaces 1004 located on opposite sides in a third direction EF, where the third direction EF is the direction from the bottom to the top of the vehicle, and the first pole post 1001 and the second pole post 1002 may be located on the second surface 1004 of the single cell 100 facing the top of the vehicle.

[0052] Furthermore, the first pole of a single cell 100 at one end of the battery array 1006 is drawn out by a conductor and corresponds to the first electrode lead terminal 211 of the battery unit 21, and the second pole of a single cell 100 at the other end of the battery array is drawn out by a conductor and corresponds to the second electrode lead terminal 212 of the battery unit 21.

[0053] In the embodiments of this application, the ratio range of the length of the single cell 100 to the length of the vehicle is 0.2 to 0.8. Specifically, in the embodiments of this application, the length L of the single cell 100 is in the range of 600 mm to 2500 mm, and may be, for example, 600 mm, 1200 mm, or 2000 mm. When the length dimension of the single cell 100 is within this range, the overall structure of the single cell 100 is conformed by a standardized design and can be used universally for different battery packs 200, with a wide range of application. The thickness of the single cell 100 extends along the second direction CD (i.e., the width direction of the vehicle), and the thickness H of the single cell 100 may be greater than 10 mm, and may be in the range of, for example, 13 mm to 75 mm.

[0054] More specifically, referring together to Figures 6 to 12, the single cell 100 includes a metal case 11 and a plurality of electrode sets 12 packaged within the metal case 11 and arranged sequentially along a first direction AB. The plurality of electrode sets 12 may be connected in series to form an electrode row, and each electrode set 12 includes at least one electrode.

[0055] The electrode set 12 includes a first electrode 121 and a second electrode 122 for drawing current, and further includes an electrode set body 123 and the first electrode 121 and the second electrode 122 electrically connected to the electrode set body 123, with the first electrode 121 and the second electrode 122 located on both sides of the electrode set body 123 along a first direction AB. Of two adjacent electrode sets 12, the first electrode 121 of one electrode set 12 and the second electrode 122 of the other electrode set 12 are electrically connected to achieve a series connection, and by connecting multiple electrode sets 12 in series, the capacity and voltage can be increased with a single cell 100, and the manufacturing process and cost can be reduced.

[0056] In this embodiment, the series connection method may involve connecting two adjacent electrode sets 12 in series. Specifically, the first electrode 121 and the second electrode 122 of two adjacent electrode sets 12 may be directly connected, or the electrical connection may be achieved via an additional conductive member. If the electrode set 12 contains only one electrode, the first electrode 121 and the second electrode 122 may be the positive electrode tab and the negative electrode tab of the electrode, respectively, or they may be the negative electrode tab and the positive electrode tab, respectively. If there are multiple electrode sets, the lead members of the first electrode 121 and the second electrode 122 may be electrode lead wires. The terms "first" and "second" in "first electrode 121" and "second electrode 122" are merely for distinguishing names and do not limit the number; for example, the first electrode 121 and the second electrode 122 may each contain one or more.

[0057] Furthermore, the metal case 11 includes a case body 111 having an opening and a cover plate 112. The cover plate 112 is sealed and connected to the opening of the case body 11, forming a sealed housing cavity together with the case body, and an electrode array formed by connecting a plurality of electrode sets 12 in series is housed in the housing cavity. Both ends of the electrode array include a first electrode and a second electrode, respectively, the first electrode of the electrode array being the first electrode 121 of the electrode set 12 located at one end of the electrode array, and the second electrode of the electrode array being the second electrode 122 of the electrode set 12 located at the other end of the electrode array.

[0058] In some embodiments, the first and second electrodes located at both ends of the electrode array are drawn out from the cover plate 112, respectively, to form the first pole column 1001 and the second pole column 1002 of the single cell 100.

[0059] Specifically, in some embodiments, the case body 111 may have openings at both ends, and there may be two cover plates 112, so that the two cover plates 112 are sealed and connected to the openings at both ends of the case body 111 to form a sealed housing cavity. In such a configuration, the first and second electrodes located at both ends of the electrode array may be drawn out from the two cover plates 112 to form the first pole column 1001 and the second pole column 1002 of the cell 100, respectively, in which case the first pole column 1001 and the second pole column 1002 are located on the first surfaces 1003 at both ends of the first direction AB of the cell 100. Naturally, in other embodiments, the first and second electrodes located at both ends of the electrode array may be drawn out from the same cover plate 112 to form the first pole 1001 and second pole 1002 of the cell 100, respectively, in which case the first pole 1001 and second pole 1002 are located on the first surface 1003 at the same end of the first direction AB of the cell 100.

[0060] In other embodiments, the case body 111 may have an opening at only one end, and since there is only one cover plate 112, the cover plate 112 is sealed and connected to the opening at one end of the case body 111. In this configuration, the first and second electrodes located at both ends of the electrode array are drawn out from the same cover plate 112 to form the first pole column 1001 and the second pole column 1002 of the single cell 100, respectively, and the first pole column 1001 and the second pole column 1002 are located at the same end of the single cell 100.

[0061] To make it easier to understand, in some other embodiments, the first and second electrodes located at both ends of the electrode array do not need to be extended from the cover plate 112, and the cover plate 112 may have a first pole column 1001 and a second pole column 1002, and furthermore, the first and second electrode terminals may both be provided on the same cover plate 112, or on two separate cover plates 112, in which case the first and second electrodes located at both ends of the electrode array are electrically connected to the first electrode terminal and the second electrode terminal on the cover plate 112, respectively, and the details are omitted here.

[0062] Furthermore, multiple electrode sets 12 may be connected in a series + parallel connection manner. For example, multiple electrode sets 12 can form two electrode rows. Specifically, multiple electrode sets 12 can be divided into two parts, where the electrode sets 12 in each part are connected in series to form one electrode row, and the two electrode rows are connected in parallel. Naturally, multiple electrode sets 12 may also be rationally divided into three or more parts, where the electrode sets 12 in each part are connected in series to form an electrode row, and the multiple electrode rows are connected in parallel. To make it easier to understand, the multiple electrode sets 12 in the single cell 100 are divided into multiple parts, and the multiple electrode sets 12 in each part are connected in series to form an electrode row. This ensures that each electrode row has a voltage of a certain magnitude and can meet the operating requirements. Furthermore, by connecting the multiple electrode rows in a parallel manner, the electrical capacities of the multiple electrode rows can be combined. As a result, the single cell 100 has a large electrical capacity, which helps to extend the power supply time of the single cell 100.

[0063] Furthermore, in the embodiments of this application, a package film 13 is further provided between the metal case 11 and the electrode set 12, i.e., the electrode set 12 is packaged within the package film 13. This enables secondary packaging of the electrode set 12 by the package film 13 and the metal case 11, which helps to improve the sealing effect of the single cell 100. As can be understood, electrolyte is further injected into the package film 13. Therefore, this method further avoids contact between the electrolyte and the metal case 11, thereby preventing corrosion of the metal case 11 or decomposition of the electrolyte.

[0064] The air pressure between the metal case 11 and the packaging film 13 is lower than the air pressure outside the metal case 11, and the air pressure inside the packaging film 13 is lower than the air pressure between the metal case 11 and the packaging film 13.

[0065] In this application, "atmospheric pressure" is an abbreviation for atmospheric pressure. It refers to the pressure of a gas acting per unit area, that is, it is equal to the weight of a vertical column of air extending upward to the upper limit of the atmosphere per unit area.

[0066] The air pressure between the metal case 11 and the packaging film 13 is also the air pressure in the space between the metal case 11 and the packaging film 13, and since this air pressure is lower than the air pressure outside the metal case 11, in the embodiment of the present invention, a negative pressure state is created between the metal case 11 and the packaging film 13. As a result, when the metal case 11 is indented or deformed by atmospheric pressure, the gap between the metal case 11 and the electrode set 12 becomes smaller, reducing the space in which the electrode set 12 can move or be displaced relative to each other. Furthermore, the movement of the electrode set 12 and the relative displacement of the electrode set 12 relative to each other can be reduced, improving the stability, strength, and safety performance of the single cell 100.

[0067] For example, by performing an air venting process on the space between the metal case 11 and the packaging film 13, a negative pressure state is created between the metal case 11 and the packaging film 13, bringing the metal case 11 as close as possible to the internal electrode set 12, reducing the internal void, preventing the electrodes from moving within the metal case, and preventing relative displacement between the electrodes. This reduces the occurrence of situations such as damage to the current collector, wrinkled separators, and detachment of active materials, improving the overall mechanical strength of the single cell 100, extending the service life of the single cell 100, and improving the safety performance of the single cell 100.

[0068] In one embodiment, the pressure between the metal case 11 and the packaging film 13 is P1, and the range of P1 may be -100 kPa to -5 kPa, and more preferably, the value of P1 may be -75 kPa to -20 kPa. Naturally, those skilled in the art can set the value of P1 according to actual needs. The space between the metal case 11 and the packaging film 13 may be a vacuum.

[0069] Furthermore, the pressure value inside the package film 13 is P2, and the range of the value of P2 may be -100 kPa to -20 kPa.

[0070] The relationship between P1 and P2 satisfies P1 > P2, and the range of P1 / P2 is 0.05 to 0.85.

[0071] By limiting P1, P2, and P1 / P2 to the above range, the electrode set 12 in this technology is first packaged in a package film 13 using a secondary sealing mode. To avoid damage to the package film 13 due to excessively high internal pressure causing the package film 13 to bulge outward, the inventors selected that the pressure between the metal case 11 and the package film 13 be greater than the pressure inside the package film 13. Furthermore, through numerous experiments, the inventors verified that when P1 / P2 is within the above range, the reliability of the secondary sealing of the single cell 100 is well guaranteed, the interface between the electrode plates of the single cell 100 is guaranteed, gaps between the electrode plates are avoided, and lithium ions are conducted more efficiently.

[0072] In the embodiment of the present invention, there is one package film 13, and multiple electrode sets 12 connected in series are packaged within the same package film 13. The connection point between the first electrode 121 of one of the two electrode sets 12 connected in series and the second electrode 122 of the other electrode set 12 is located within the package film 13. That is, the package film 13 is provided integrally, and multiple electrode sets 12 are packaged within the same package film 13.

[0073] In actual applications, for example, as shown in Figure 10, first multiple electrode sets 12 are connected in series, then a single package film 13 is used to wrap the series-connected electrode sets 12, for example, by placing the series-connected electrode sets 12 in a portion of the package film 13 (or by pre-forming a groove in a portion of the package film 13 and then placing the series-connected multiple electrode sets 12 in the groove), then another portion of the package film 13 is folded in the direction of the electrode sets 12, and then the two portions of the package film 13 are heat-sealed by a heat-sealing process, thereby packaging the series-connected electrode sets 12 within the same package film 13.

[0074] A package portion 131 is formed in the package film 13 at a position corresponding to the first electrode 121 and / or the second electrode 122, separating the two adjacent electrode body sets 123, and separating the first electrode 121 of one of the two adjacent electrode body sets 12 from the other electrode body set 12 At least one of the second electrodes 122 is located inside the package portion 131. The package portion 131 separates the multiple electrode body sets 123 from each other, preventing the electrolytes of the multiple electrode body sets 12 from flowing to each other. The multiple electrode body sets 12 do not affect each other, and the electrolytes in the multiple electrode body sets 12 do not decompose due to a large potential difference, thus ensuring the safety and service life of the single cell 100.

[0075] The package portion 131 may have various embodiments. For example, the package portion 131 may be formed by fastening the package film 13 with a cable tie, or the package portion 131 may be formed by directly heat-sealing and connecting the package film 13. Alternatively, the package portion 131 may be configured by directly providing a separator between the two electrode sets 12. The specific method of the package portion 131 is not particularly limited.

[0076] In other embodiments of the present invention, as shown in Figure 11, there are multiple package films 13, and at least one electrode set 12 is packaged within one package film 13 to form an electrode assembly, and the multiple electrode assemblies are connected in series.

[0077] In other words, there is a one-to-one correspondence between the number of package films 13 and the number of electrode sets 12, and each electrode set 12 is packaged individually in one package film 13. In such embodiments, after the manufacturing of multiple electrode sets 12 is complete, one package film 13 can be fitted individually onto the outside of each electrode set 12, and then the multiple electrode assemblies can be connected in series.

[0078] At least one of the first electrode 121 and the second electrode 122 of the electrode assembly 12 extends from the package film 13. For example, the first electrode 121 may extend from the package film 13, the second electrode 122 may extend from the package film 13, or both the first electrode 121 and the second electrode 122 may extend from the package film 13. By having at least one first electrode 121 and / or second electrode 122 extend from the package film 13, the extended electrode can be connected in series to other electrode assemblies.

[0079] In the embodiment of the present invention, the arrangement direction of the multiple electrode sets 12 is a first direction AB, the length direction of the electrode sets 12 extends along the first direction AB, and the length of the single cell 100 also extends along the first direction AB. That is, the multiple electrode sets 12 are arranged sequentially along the length direction of the single cell 100, and the first electrode 121 and the second electrode 122 of the electrode set 12 are located on both sides of the electrode set 12 along the first direction AB. That is, the multiple electrode sets 12 use a "head-to-head" arrangement method, and this arrangement method makes it easy to connect two electrode sets 12 in series, resulting in a simple connection structure. Furthermore, this arrangement method makes it easy to manufacture long single cells 100. When installing the single cells 100 inside the battery pack case, there is no need to provide support structures such as horizontal and vertical beams. The single cells 100 can be directly attached to the battery pack case using the metal case 11 of the single cell 100 itself as a support. This saves internal space in the battery pack, improves the volume utilization rate of the battery pack, and helps to reduce the weight of the battery pack.

[0080] Compared to conventional methods that use only one electrode, providing multiple electrode sets 12 within a single cell 100 makes it easier to manufacture longer single cells 100. In conventional batteries, as the battery length increases, the length of the internal copper-aluminum foil used as a current collector also increases, significantly increasing the internal resistance of the battery and making it impossible to meet the increasingly high power and rapid charging requirements. When the battery length is the same, the embodiment of the present invention significantly reduces the internal resistance of the battery, thus avoiding problems such as battery overheating in the case of high power output and rapid charging.

[0081] As shown in Figure 12, the metal case 11 has two third surfaces 1005 facing each other along the second direction CD, and these third surfaces 1005 are also the largest surface of the cell 100 and the "large surface" of the cell 100. At least one of the third surfaces 1005 is recessed into the interior of the metal case 11, thereby allowing the metal case 11 and the electrode set 12 to adhere as closely as possible.

[0082] Since the metal case 11 is a thin sheet with a small thickness, the recess 114 on the third surface 1005 of the metal case 11 may be a recess formed, for example, when air is removed from inside the metal case 11. That is, when the air pressure between the metal case 11 and the package film 13 is lower than the air pressure outside the metal case 11 due to the air removal process in the space between the metal case 11 and the package film 13, the third surface 1005 of the metal case 11 is likely to sink inward into the metal case 11 as the air removal progresses, forming the recess 114.

[0083] During the normal operation of a single cell 100, the cell generally expands due to the expansion of the material itself and the generation of gas from the electrolyte. The area of ​​greatest expansion deformation is usually located on the large surface of the cell. Using this technology, in the initial state of the cell, the large surface is formed to slightly indent inward by vacuuming, effectively mitigating the pressure between cells after expansion and improving the lifespan and safety performance of the battery and the entire system.

[0084] In some other embodiments, as shown in Figure 12, recesses may be pre-formed on the third surface 1005 of the metal case 11, and then an air venting process may be performed inside the metal case 11. There may be multiple recesses 114 on the third surface 1005 of the metal case 11; for example, multiple recesses 114 may be pre-formed on the third surface 1005, and the position of each recess 114 corresponds to the position of one electrode set 12.

[0085] In some embodiments, the two opposing third surfaces 1005 of the metal case 11 are both recessed inward, and the recessed areas hold the electrode set 12.

[0086] The metal case 11 is provided with air vents, allowing air to be vented from the space between the metal case 11 and the packaging film 13. Since the air vents need to be sealed, a sealing member is further provided inside the air vents to seal them. This sealing member may be, for example, a plug or a rubber member, but is not limited to these.

[0087] In some embodiments, a gap is provided between the electrode set 12 and the inner surface of the metal case 11 before the air is removed from the metal case 11, and this gap makes it easier to install the electrode set 12 inside the metal case 11. After the air is removed from the metal case 11, the metal case 11 is pressed against the outer surface of the electrode set 12 along a second direction, clamping the electrode set 12, thereby reducing the space in which the electrode set 12 moves inside the metal case 11 and improving the safety performance of the single cell 100.

[0088] In the embodiments of this application, the metal case 11 has high strength and high heat dissipation effect, and the metal case 11 includes, but is not limited to, an aluminum case or a steel case. In some embodiments, the thickness of the metal case 11 is 0.05 mm to 1 mm.

[0089] If the metal case 11 is too thick, it not only increases the weight of the single cell 100 and reduces its capacity, but if the metal case 11 is too thick, atmospheric pressure will make it difficult for the metal case 11 to indent or deform towards the electrode set 12, preventing the gap between the metal case 11 and the electrode set 12 from being reduced, and further preventing it from effectively performing its role in positioning the electrode set 12. Moreover, if the metal case 11 is too thick, the cost of air venting increases, thus increasing manufacturing costs.

[0090] This invention not only guarantees the strength of the metal case 11 by limiting the thickness of the metal case 11 to the above range, but also does not reduce the capacity of the single cell 100, and furthermore, under negative pressure conditions the metal case 11 is more easily deformed, and by reducing the distance between the metal case 11 and the electrode set 12, the movement of the electrode set 12 inside the metal case 11 and the relative displacement of the electrode sets 12 themselves are reduced.

[0091] In the embodiments of the present invention, the package film 13 includes a laminated nonmetallic outer film and a nonmetallic inner film, the inner film being located between the outer film and the electrode set 12.

[0092] The inner layer film may be made of a material with high chemical stability, such as resistance to electrolyte corrosion, for example, polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), or a combination of several of the above materials.

[0093] The outer layer film is a protective layer that can prevent the penetration of air, especially water vapor and oxygen. The outer layer film may be, for example, polyethylene terephthalate, polyamide (PA, Polyamide), or polypropylene, or a combination of several of the above materials.

[0094] In the package film 13 of this embodiment, since the melting point of the outer layer film is greater than that of the inner layer film, when heat-sealed, the outer layer film does not melt, and the inner layer film melts in a timely manner, thereby ensuring excellent sealing performance. Furthermore, the range of the melting point difference between the outer layer film and the inner layer film is 30°C to 80°C, and for example, the melting point difference between the two may be 50°C or 70°C, and the specific materials can be selected according to actual demand.

[0095] The non-metallic outer film and the non-metallic inner film are bonded together with an adhesive to form a composite film. For example, to form a composite film by bonding, the material of the outer film may be PP, the material of the inner film may be PET, and the adhesive used to bond them together may be, for example, a polyolefin-based adhesive.

[0096] In this embodiment, the electrode set 12 is packaged by forming a package film 13 using two layers of non-metallic film. Because a non-metallic package film 13 is used, the tensile strength and elongation at break are increased, and the limitations on the thickness of the single cell 100 can be reduced, resulting in a thicker single cell 100. The thickness of the single cell 100 in this embodiment has a wide range of expandability, for example, greater than 10 mm, and may be in the range of 13 mm to 75 mm.

[0097] In some embodiments of the present application, the package film 13 may be an aluminum laminate film.

[0098] In one embodiment of the present invention, the single cell 100 is a lithium-ion battery.

[0099] In the embodiment of the present invention, in the same battery unit 21, in the single cells arranged sequentially along the second direction CD, there is a gap between two adjacent single cells 100, and the ratio range of the gap to the thickness of the single cell 100 is 0.001 to 0.15.

[0100] Furthermore, although the gap between two adjacent batteries changes as the battery operating time increases, as long as the ratio of the gap between the batteries to their thickness is within the range limited by this application, whether during operation, after operation, or before the batteries are shipped, they are all within the scope of protection of this application.

[0101] In this invention, the certain gap left between the individual cells 100 can serve as a buffer space in case the individual cells 100 expand.

[0102] The expansion of a single cell 100 is related to its thickness; the thicker the cell, the more easily it expands. In this invention, by limiting the ratio of the gap between single cells 100 to the thickness of each cell 100 to 0.001 to 0.15, the space in the battery pack 200 can be fully utilized, improving the utilization rate of the battery pack 200, and providing an excellent buffering effect against the expansion of single cells 100.

[0103] Furthermore, since a single cell 100 generates heat when it expands, a certain gap is left between the single cells 100. This gap can also function as a heat dissipation passage, such as an air duct. Because the heat dissipation effect is higher on the larger surface area of ​​the single cell 100, the heat dissipation efficiency of the battery pack 200 can be improved, thereby improving the safety performance of the battery pack 200.

[0104] In the above method, the gap between the individual cells 100 can be understood as simply leaving a certain amount of space without providing any structural members between them. Furthermore, by providing other structural members to the individual cells 100, it can be understood that the individual cells 100 are separated by the structural members.

[0105] Furthermore, when a structural member is provided between two individual cells 100, the gap between the individual cells 100 should be understood as the distance between the individual cells 100 on either side of the structural member, rather than the distance between the structural member and the individual cell 100.

[0106] Furthermore, a certain gap may be left between the structural member and the single cells 100 on both sides of the structural member, or they may be in direct contact. If the structural member is in direct contact with the single cells 100 on both sides, the structural member must have a certain degree of flexibility so that it can act as a buffer when the single cells 100 expand. The structural member includes, but is not limited to, aerogel, thermally conductive structural adhesive, or insulating cotton.

[0107] The present invention further provides an electric vehicle including the battery pack 200, which has the same advantages as the battery pack 200 over related technologies, and therefore will not be described here.

[0108] In this description, unless otherwise clearly specified or limited, the terms "attachment," "connection," and "connection" should be understood in a broad sense. For example, a connection may be fixed, detachable, or integral; a connection may be mechanical or electrical; a connection may be direct or indirect via an intermediate medium; or it may be internal communication between two parts. A person skilled in the art will be able to understand the specific meaning of these terms in this description depending on the specific circumstances.

[0109] In this specification, any reference to terms such as "examples," "specific examples," or "examples" means that the specific features, structures, materials, or properties described in combination with such examples are included in at least one example of this application. In this specification, the exemplary expressions of the above terms are not necessarily limited to the same example or example. Furthermore, the specific features, structures, materials, or properties described may be appropriately combined in any one or more examples.

[0110] Although embodiments of this application have been described as examples, as will be understood by those skilled in the art, various changes, modifications, substitutions, and alterations can be made to these embodiments without departing from the principles and spirit of this application, and the scope of this application is limited by the claims and their equivalents.

Claims

1. A battery pack that provides electrical energy to a vehicle, comprising at least one battery unit, the battery unit comprising at least one battery array, the battery array comprising a plurality of single cells, and the potential difference across the battery array being 45V or more and 60V or less. The plurality of single cells in the battery array are arranged sequentially along a first direction, and the first direction is parallel to the direction from the rear to the front of the vehicle. The length of the single cell extends along the first direction, The single cell includes a first pole and a second pole, and the single cell has two first surfaces located on opposite sides along the first direction. A battery pack characterized in that the first pole and the second pole are located on the same first surface of a single cell, or are located on two separate first surfaces of a single cell.

2. The battery pack according to claim 1, characterized in that the battery unit includes a plurality of battery rows, the plurality of battery rows are arranged sequentially along a second direction, the second direction being the width direction of the vehicle.

3. The battery pack according to claim 2, characterized in that the battery rows are connected in series and / or in parallel.

4. The battery pack according to claim 1, characterized in that, if the battery array includes at least two single cells, the single cells in the battery array are connected in series.

5. The battery pack according to claim 1, characterized in that there are multiple battery units, and the battery units are connected in series with each other.

6. The battery pack according to claim 5, wherein a plurality of battery units are arranged in an array to form a battery unit array, the battery unit array includes a plurality of rows of battery unit sets, the plurality of rows of battery unit sets are arranged sequentially along a first direction, and an active safety device is located between two adjacent rows of battery unit sets and connected between two battery units that are electrically connected to each other.

7. The battery pack according to claim 6, characterized in that the active safety device is a relay or a fuse.

8. The battery pack according to claim 1, characterized in that the ratio range of the length of at least one of the single cells to the length of the vehicle is 0.2 to 0.

8.

9. The battery pack according to claim 1, characterized in that the length range of the single cell is 600 mm to 2500 mm.

10. An electric vehicle characterized by including a battery pack according to any one of claims 1 to 9.

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