Battery cell and battery pack

Abstract

A battery cell (1000) and a battery pack. The battery cell (1000) comprises a casing (110), a reinforcing plate (120) and a battery core (200); the casing (110) comprises a plurality of side plates; the plurality of side plates define a cavity (2); the battery core (200) is mounted in the cavity (2); the plurality of side plates include a first side plate (111); the first side plate (111) is provided with a pressure relief opening (115); the pressure relief opening (115) is used for discharging gas in the cavity (2); the reinforcing plate (120) is arranged in the cavity (2) and connected to the surface of the first side plate (111) located in the cavity (2); the area of the surface of the first side plate (111) located in the cavity (2) is S2, and the area of the surface of the reinforcing plate (120) facing the first side plate (111) is S1, wherein 0.5≤S1 / S2≤1; in this case, the contact area between the reinforcing plate (120) and the battery core (200) is relatively large, so that the battery core (200) is not prone to short-circuiting and collapsing under the compression of the reinforcing plate (120).

Description

Single cells and battery packs

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 25, 2024, with application number 202420190006.9 and application name “Single Cell and Battery Pack,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a single cell and a battery pack. Background Art

[0003] Some single-cell battery cells use a double-ended aluminum shell with two openings at both ends. The double-ended aluminum shell consists of a reinforcing plate and a cylindrical shell, with the reinforcing plate welded to the inside of the cylindrical shell. However, this can lead to defects such as short circuits and collapse of the battery cells.

[0004] Application Contents

[0005] The embodiments of the present application provide a single cell and a battery pack, in which the battery cells are not easily short-circuited or collapsed under the compression of a reinforcing plate.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] On the one hand, a single battery is provided, comprising a shell, a reinforcing plate and a battery cell.

[0008] The housing includes a plurality of side panels, the plurality of side panels enclosing a cavity, the battery cell being installed in the cavity, the plurality of side panels including a first side panel, the first side panel being provided with a pressure relief port, the pressure relief port being used to discharge gas in the cavity,

[0009] The reinforcing plate is disposed in the cavity and connected to the surface of the first side plate located in the cavity.

[0010] The surface area of ​​the first side plate in the cavity is S2, and the surface area of ​​the reinforcing plate facing the first side plate is S1, wherein 0.5≤S1 / S2≤1.

[0011] In some embodiments, the reinforcing plate is welded to the first side plate, the thickness of the reinforcing plate is t1, and the thickness of the first plate is t2, wherein 0.8 mm ≤ t1 + t2 ≤ 2.5 mm.

[0012] In some embodiments, 0.4 mm ≤ t1 ≤ 1.2 mm.

[0013] In some embodiments, 0.4 mm ≤ t2 ≤ 1.3 mm.

[0014] In some embodiments, 0.4 mm ≤ t1 ≤ 1.2 mm, and 0.4 mm ≤ t2 ≤ 1.3 mm.

[0015] In some embodiments, the reinforcing plate is provided with an explosion-proof valve, which is arranged opposite to the pressure relief port. The reinforcing plate includes one or more welding areas, which are welded to the first side plate and surround the pressure relief port.

[0016] In some embodiments, a boss is provided on a side of the reinforcing plate facing the first side plate, the boss extends into the pressure relief port, and the boss is welded to an edge of the pressure relief port.

[0017] In some embodiments, the shell further includes a second side panel, a third side panel and a fourth side panel, the second side panel is opposite to the first side panel, the third side panel is opposite to the fourth side panel, and the third side panel and the fourth side panel are located between the first side panel and the second side panel, and the first side panel, the second side panel, the third side panel and the fourth side panel are an integrated plate structure, which are bent to form the shell.

[0018] In some embodiments, the second side plate includes a first plate connected to the third side plate and a second plate connected to the fourth side plate, and the first plate and the second plate are welded to make the shell present a closed cylindrical structure.

[0019] In some embodiments, the first plate and the second plate are welded to form a weld.

[0020] In some embodiments, the weld has a penetration depth greater than or equal to 0.2 mm.

[0021] In some embodiments, the weld width is greater than or equal to 0.3 mm.

[0022] In some embodiments, the penetration depth of the weld is greater than or equal to 0.2 mm, and the penetration width of the weld is greater than or equal to 0.3 mm.

[0023] In some embodiments, the single battery further includes an end cover, which is buckled onto the shell, so that the end cover and the shell together enclose the cavity.

[0024] On the other hand, a battery pack is provided, comprising the above-mentioned single battery.

[0025] In the single cell and battery pack provided in the embodiments of the present application, the reinforcing plate is arranged in the cavity and connected to the surface of the first side plate located in the cavity. The surface area of ​​the first side plate located in the cavity is S2, and the surface area of ​​the reinforcing plate facing the first side plate is S1, wherein 0.5≤S1 / S2≤1. When S1 / S2≥0.5, the area of ​​the reinforcing plate is larger, and at this time, the contact area between the reinforcing plate and the battery cell is larger. When the interaction force between the battery cell and the reinforcing plate is equal, the contact area between the reinforcing plate and the battery cell is larger, so that the pressure exerted by the reinforcing plate on the battery cell is smaller, thereby reducing defects such as folding, short circuiting or partial collapse of the battery cell caused by excessive pressure.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] FIG1 is a schematic structural diagram of a single cell provided in an embodiment of the present application;

[0029] FIG2 is an exploded schematic diagram of a single cell provided in an embodiment of the present application;

[0030] FIG3 is a schematic diagram of a shell of a single cell provided in an embodiment of the present application;

[0031] FIG4 is an exploded schematic diagram of a shell of a single cell provided in an embodiment of the present application;

[0032] FIG5 is a schematic diagram of a shell of a single cell provided in an embodiment of the present application;

[0033] FIG6 is an exploded schematic diagram of a reinforcement plate in an embodiment of the present application;

[0034] FIG7 is a schematic diagram of a reinforcement plate in an embodiment of the present application;

[0035] FIG8 is a cross-sectional view of FIG7 about BB;

[0036] FIG9 is an exploded schematic diagram of a reinforcement plate in an embodiment of the present application;

[0037] FIG10 is a schematic diagram of a reinforcement plate in an embodiment of the present application;

[0038] FIG11 is a view taken along the line A of FIG5 ;

[0039] FIG12 is a cross-sectional view of CC in FIG11 ;

[0040] FIG13 is a partial enlarged view of point I in FIG12;

[0041] FIG14 is a side view of the housing in an embodiment of the present application.

[0042] Reference numerals:

[0043] 1000-single cell;

[0044] 110 - housing; 111 - first side panel; 112 - second side panel; 113 - third side panel; 114 - fourth side panel; 115 - pressure relief port; 110a - first opening; 110b - second opening; 1 - weld; 2 - cavity;

[0045] 120-reinforcement plate; 121-explosion-proof valve; 122-plate body; 123-through hole; 124-boss;

[0046] 200-battery cells;

[0047] 300-first end cover;

[0048] 400-second end cover;

[0049] 1121-first section; 1122-second section. Specific embodiments

[0050] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0051] In the embodiments of the present application, words such as "first", "second", "third", and "fourth" are used to distinguish between identical or similar items with basically the same functions and effects. This is only for the purpose of clearly describing the technical solutions of the embodiments of the present application, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0052] In the embodiments of the present application, “a plurality of” means two or more, and “at least one” means one or more, unless otherwise clearly defined.

[0053] The present application provides a battery pack, which can be a power battery pack used in electric vehicles to provide power to the electric vehicle's drive motor, etc. Of course, the battery pack can also be other types of battery packs, such as those used in electric bicycles and electric motorcycles. The present application does not limit the type of battery pack or its application scenario.

[0054] The battery pack includes a housing and individual cells housed within it. The housing protects the individual cells from impact. The housing may include a mounting cavity, into which the individual cells are mounted.

[0055] The battery pack may also include a thermal management component connected to the individual cells to regulate the temperature of the individual cells. For example, multiple individual cells are arranged in an array, and the arrayed multiple individual cells form multiple cell groups. Each cell group includes multiple individual cells. The multiple individual cells within a battery group are arranged sequentially along a straight line, and the multiple cell groups are arranged in intervals perpendicular to the straight line. The thermal management component is located between two adjacent cell groups, with one side of the thermal management component connected to the individual cells in one cell group and the opposite side of the thermal management component connected to the individual cells in the other cell group.

[0056] Among them, the connection between the thermal management component and the single cell refers to any combination method in which the heat generated by the single cell can be transferred to the thermal management component through heat transfer. The thermal management component can be in direct contact or physical connection with the single cell, or the thermal management component can be connected to the single cell through other heat-conducting media to achieve heat transfer.

[0057] In actual application, the box body may be provided with a charging interface for charging and a discharging interface for discharging, and the installation cavity in the box body may also be provided with modules such as a battery management system.

[0058] The battery pack may include multiple single cells arranged in an array. When multiple single cells are arranged in a box, the multiple single cells may be connected in series or in parallel.

[0059] For example, multiple single cells in the same single cell group are connected in series. Two adjacent single cell groups can be connected in series or in parallel.

[0060] Figure 1 is a schematic diagram of the structure of a single cell provided in an embodiment of the present application, Figure 2 is an exploded schematic diagram of a single cell provided in an embodiment of the present application, and Figure 3 is a schematic diagram of the housing of a single cell provided in an embodiment of the present application. As shown in Figures 1 to 3, single cell 1000 includes a housing 110 and a battery cell 200. The housing 110 has a cavity 2, and the battery cell 200 is accommodated in the cavity 2.

[0061] The single battery 1000 further includes a first electrode assembly and a second electrode assembly. The battery cell 200 has a first electrode tab and a second electrode tab. The first electrode assembly is electrically connected to the first electrode tab, and the second electrode assembly is electrically connected to the second electrode tab. The single battery 1000 realizes the charging and discharging of the battery cell 200 through the first electrode assembly and the second electrode assembly. The battery cell 200 can be a wound battery cell 200 or a stacked battery cell 200. The embodiment of the present application does not limit the type of battery cell 200.

[0062] The single cell 1000 may further include an end cover, which is buckled onto the housing 110 so that the end cover and the housing 110 together form a cavity 2. The single cell 1000 may include one end cover or two end covers.

[0063] When the single cell 1000 includes an end cap, the first terminal assembly and the second terminal assembly can be simultaneously disposed on the end cap. In this case, the housing 110 can be a single-opening housing, that is, the housing 110 is open only on one side, with the other sides closed, and an end cap fastened to the opening.

[0064] When the single cell 1000 includes two end caps, the first pole assembly can be arranged on one of the end caps, and the second pole assembly can be arranged on the other end cap. In this case, the shell 110 can be a two-way shell, that is, the shell 110 is open on two opposite sides, and an end cap is fastened to each opening. For example, referring to Figures 1 to 3, the shell 110 is a cylindrical structure, and the shell 110 includes a first opening 110a and a second opening 110b that are arranged opposite to each other. The end caps include a first end cap 300 and a second end cap 400. The first end cap 300 is fastened to the first opening 110a, and the second end cap 400 is fastened to the second opening 110b. The first pole assembly is arranged on the first end cap 300, and the second pole assembly is arranged on the second end cap 400.

[0065] For the sake of convenience, the following describes in detail the single cell 1000 provided in the embodiment of the present application by taking the shell 110 as a double-pass shell as an example.

[0066] Continuing to refer to FIG. 3 , the housing 110 includes a plurality of side panels, which enclose a cavity 2 .

[0067] Figure 4 is an exploded schematic diagram of a battery cell housing provided in an embodiment of the present application. For example, as shown in Figure 4, the multiple side panels of the housing 110 include a first side panel 111, a second side panel 112, a third side panel 113, and a fourth side panel 114. The first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 together form a cylindrical structure with two open ends. The first side panel 111 and the second side panel 112 are positioned opposite each other, while the third side panel 113 and the fourth side panel 114 are positioned opposite each other.

[0068] In actual application, the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 in the housing 110 can be made by an integral molding process. For example, the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 can be made by an integral molding process such as stamping, stretching, or hot extrusion.

[0069] Of course, the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 in the housing 110 can also be manufactured by other processes. For example, the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 are an integrated plate structure, which is formed by welding a plate-like member after being bent multiple times.

[0070] The thicknesses of the first side plate 111, the second side plate 112, the third side plate 113, and the fourth side plate 114 may be equal or unequal. Optionally, the thicknesses of the first side plate 111, the second side plate 112, the third side plate 113, and the fourth side plate 114 are equal to reduce the difficulty of the manufacturing process of the housing 110.

[0071] Exemplarily, the thickness of the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 is 0.1 mm to 1.3 mm. For example, the thickness of the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 is any value selected from 0.4 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1.0 mm, and 1.3 mm, or a value within a range consisting of any two of these values.

[0072] If the first, second, third, and fourth side panels 111, 112, 113, and 114 are too thin, the housing 110 may easily deform and fail to meet usage requirements. For example, the battery cell 200 includes two large surfaces and multiple small surfaces, where the large surfaces are larger than the small surfaces. The third and fourth side panels 113, 114 of the housing 110 are each positioned opposite a large surface. If the first, second, third, and fourth side panels 111, 112, 113, and 114 are too thin, the third and fourth side panels 113, 114 may easily deform.

[0073] If the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 are too thick, the fillets between adjacent side panels are large, making them difficult to form. For example, if the first side panel 111, the second side panel 112, the third side panel 113, and the fourth side panel 114 are formed by bending a plate-like member multiple times, the thickness makes them difficult to bend, or the fillets after bending are large, resulting in a reduction in the space within the cavity 2.

[0074] The first side plate 111 is provided with a pressure relief vent 115, which communicates with the cavity 2 and is used to discharge gas within the cavity 2. The pressure relief vent 115 is a hole formed on the first side plate 111 and extends through the thickness of the first side plate 111. For example, if a single battery cell 1000 experiences thermal runaway, the high-temperature, high-pressure gas within the cavity 2 is discharged through the pressure relief vent 115.

[0075] Illustratively, the first side plate 111 serves as the base plate of the battery cell 1000. For example, when the battery pack is installed in an electric vehicle as a power battery pack, the first side plate 111 faces the ground. In the event of thermal runaway in a battery cell 1000, the battery cell 1000 releases high-temperature, high-pressure gas to the ground through the pressure relief vent 115, rather than into the passenger compartment, providing some protection for the occupants.

[0076] Continuing with Figure 4 , to prevent the battery cells 200 from squeezing the first side plate 111 and causing deformation of the first side plate 111, the single battery cell 1000 further includes a reinforcing plate 120. The reinforcing plate 120 is positioned within the cavity 2 and is connected to the surface of the first side plate 111 located within the cavity 2. For example, the first side plate 111 and the reinforcing plate 120 are stacked, and the thickness of the connected structure increases, thereby increasing the rigidity of the connected structure and making it less susceptible to deformation.

[0077] The reinforcing plate 120 and the first side plate 111 may be connected by welding processes such as laser penetration welding, ultrasonic heat fusion welding, and brazing, or may be bonded by adhesive.

[0078] Exemplarily, the reinforcing plate 120 and the first side plate 111 are both made of metal materials (such as aluminum or aluminum alloy), and the reinforcing plate 120 and the first side plate 111 are connected by a welding process.

[0079] The surface area of ​​the first side plate 111 within the cavity 2 is S2, and the surface area of ​​the reinforcing plate 120 facing the first side plate 111 is S1, where 0.5 ≤ S1 / S2 ≤ 1. For example, S1 / S2 is any value selected from 0.5, 0.6, 0.7, 0.8, 0.9, and 1, or a value within a range consisting of any two values.

[0080] Among them, the first side plate 111 is usually a rectangular plate structure with a length dimension and a width dimension. The surface area S2 of the first side plate 111 located in the cavity 2 can be obtained by measuring its length dimension and width dimension with a ruler and then multiplying the two.

[0081] The surface area S1 of the reinforcing plate 120 facing the first side plate 111 refers to the contact area between the reinforcing plate 120 and the first side plate 111. For example, the reinforcing plate 120 and the first side plate 111 are stacked, and the orthographic projection area of ​​the reinforcing plate 120 on the first side plate 111 is S1.

[0082] In actual application, if the reinforcing plate 120 is a regular shape, such as a rectangle, the area S1 of the reinforcing plate 120 can be obtained by measuring the length and width of the reinforcing plate 120; if the reinforcing plate 120 is an irregular shape, the area S1 of the reinforcing plate 120 can be obtained through a visual inspection system.

[0083] When 0.5≤S1 / S2≤1, the area of ​​the reinforcing plate 120 is larger, and the contact area between the reinforcing plate 120 and the battery cell 200 is larger. When the battery cell 200 and the reinforcing plate 120 generate an interaction force, the larger contact area between the reinforcing plate 120 and the battery cell 200 reduces the pressure exerted by the reinforcing plate 120 on the battery cell 200, thereby reducing defects such as bending, short circuiting, or partial collapse of the battery cell 200 caused by excessive pressure.

[0084] When S1 / S2 is less than 0.5, that is, the area of ​​the reinforcing plate 120 is small, the contact area between the reinforcing plate 120 and the battery cell 200 is small, and the pressure exerted by the reinforcing plate 120 on the battery cell 200 is large. The battery cell 200 is prone to bend, short-circuit, and partial collapse under the action of high pressure.

[0085] In order to better illustrate the advantageous effects of the technical solution provided by this application, please refer to Table 1 below, which provides single cells used in experimental testing. The specific testing method is as follows:

[0086] Eleven single cells 1000 are prepared and labeled as serial numbers 1 to 11, respectively. From serial number 1 to serial number 11, the values ​​of S1 / S2 in the single cells 1000 are 0.1, 0.2, 0.3, 0.4, 1.1, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0, respectively, that is, 0.1≤S1 / S2≤1.

[0087] According to the vibration test requirements of GB 38031-2020, a vibration test is performed on 11 single cells 1000. After the vibration test is completed, the status of the battery cells 200 is observed visually or by X-ray or CT technology.

[0088] Table 1

[0089] As shown in Table 1, when S1 / S2 is greater than or equal to 0.5, the battery cell 200 is in good condition. When S1 / S2 is less than 0.5, the battery cell 200 may experience a short circuit or partial collapse defect. When S1 / S2 is greater than 1.0, the reinforcing plate 120 is too large, making it impossible to assemble smoothly and increasing the difficulty of assembly.

[0090] In some embodiments, the reinforcing plate 120 is welded to the first side plate 111. The thickness of the reinforcing plate 120 is t1, and the thickness of the first side plate 111 is t2, where 0.8 mm ≤ t1 + t2 ≤ 2.5 mm. For example, t1 + t2 is any value selected from 0.8 mm, 1 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, and 2.5 mm, or a value within a range consisting of any two values.

[0091] When t1 + t2 is less than 0.8 mm, the first side plate 111 and the reinforcing plate 120 may deform under the pressure of the battery cell 200, resulting in a reduction in the yield rate of the single battery 1000. For example, if the reinforcing plate 120 is equipped with an explosion-proof valve 121, significant deformation of the reinforcing plate 120 may cause the explosion-proof valve 121 to open below the set value, posing a safety hazard and being deemed to have failed, thereby reducing the yield rate of the single battery 1000. When t1 + t2 is greater than 2.5 mm, the overall weight of the housing 110 increases, and the energy density of the battery cell 200 decreases.

[0092] In order to better illustrate that the technical solution provided by this application has a better beneficial effect, please refer to Table 2 below. The specific test method is as follows:

[0093] Eight types of single cells 1000 were prepared, with 100 cells of each type corresponding to one type of single cell 1000 in each embodiment 7-12. The parameters and test results of the eight types of single cells 1000 are shown in Table 2 below.

[0094] The values ​​of t1+t2 for single cell 1000 are 0.5mm, 0.8mm, 1.1mm, 1.3mm, 1.5mm, 2mm, 2.5mm, and 2.7mm, respectively. The two openings of housing 110 are sealed, and air is inflated into housing 110 through the injection port using a pneumatic loader to simulate the thermal runaway gas production process within battery cell 200 until explosion-proof valve 121 bursts open. The internal pressure data at the time of valve opening is recorded. If the internal pressure of housing 110 at the time of valve opening is lower than or higher than the threshold for opening explosion-proof valve 121, housing 110 is deemed unqualified. If the internal pressure at the time of bursting is within the threshold range, housing 110 is deemed qualified and the test has passed.

[0095] Among them, S1 / S2 is equal to 0.8, and the thickness t1 of the reinforcing plate 120 can be 0.4 mm to 1.2 mm. For example, t1 is any value among 0.4 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1.0 mm, 1.2 mm, or a value in a range consisting of any two values.

[0096] When the thickness t1 of the reinforcing plate 120 is less than 0.4 mm, the thickness of the reinforcing plate 120 is relatively thin, and there is a possibility of welding through when the reinforcing plate 120 is welded to the first side plate 111, resulting in failure of the sealing of the connection surface; when the thickness t1 of the reinforcing plate 120 is greater than 1.2 mm, the thickness of the reinforcing plate 120 is too thick, and it is easy to cause cold welding when the reinforcing plate 120 is welded to the first side plate 111, which also leads to failure of sealing.

[0097] The thickness t2 of the first side plate 111 may be 0.4 mm to 1.3 mm. For example, t2 is any value among 0.4 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1.0 mm, 1.2 mm, 1.3 mm, or a value in a range consisting of any two values.

[0098] In actual application, the thicknesses of the first side panel 111, the second side panel 112, the third side panel 113 and the fourth side panel 114 are equal. When the thickness t2 of the first side panel 111 is less than 0.4 mm, the shell 110 may be deformed, which reduces the manufacturing yield. When the thickness t2 of the first side panel 111 is greater than 1.3 mm, the shell 110 is difficult to form, resulting in a lower pass rate of the flatness test results of the shell 110.

[0099] Whether the flatness is qualified is defined as follows: if the flatness is less than 0.5, the housing 110 is qualified; if the flatness is greater than or equal to 0.5, the housing 110 is unqualified.

[0100] Table 2

[0101] As shown in Table 2, when 0.8mm≤t1+t2≤2.5mm, and 0.5≤S1 / S2≤1, the blasting test pass rate reaches 100%, the welding effect test pass rate is 100%, and the shell forming flatness test result is qualified. When t1+t2<0.8mm, the blasting test pass rate is 96%, which is relatively lower, and the shell forming flatness test result is qualified. The welding effect test pass rate is 96%, which is relatively lower, and the shell forming flatness test result is qualified. When the range value is greater than 2.5mm, the blasting test pass rate reaches 100%, the welding effect test pass rate is 100%, but the shell forming flatness test result value is relatively high, and the flatness is poor.

[0102] Figure 5 is a schematic diagram of a housing 110 in a single cell 1000 provided in an embodiment of the present application, Figure 6 is an exploded schematic diagram of a reinforcing plate 120 in an embodiment of the present application, Figure 7 is a schematic diagram of a reinforcing plate 120 in an embodiment of the present application, Figure 8 is a cross-sectional view of the BB in Figure 7, Figure 9 is an exploded schematic diagram of a reinforcing plate 120 in an embodiment of the present application, and Figure 10 is a schematic diagram of a reinforcing plate 120 in an embodiment of the present application. As shown in Figures 5 to 10, in some embodiments, the reinforcing plate 120 is provided with an explosion-proof valve 121, which is disposed opposite the pressure relief vent 115. The reinforcing plate 120 includes one or more welded areas, which are welded to the first plate and surround the pressure relief vent 115.

[0103] The welding area surrounding the pressure relief port 115 can seal the reinforcing plate 120 and the periphery of the pressure relief port 115 , thereby preventing the electrolyte in the cavity 2 from leaking out of the pressure relief port 115 through the gap between the reinforcing plate 120 and the first side plate 111 .

[0104] For example, the welding area is annular and surrounds the pressure relief port 115. Two welding areas can be provided to prevent defects such as cold welding in one of the welding areas, which would result in poor sealing.

[0105] The explosion-proof valve 121 can be integrally formed with the reinforcement plate 120. For example, the explosion-proof valve 121 can be a portion of the reinforcement plate 120, which can be provided with notches. The explosion-proof valve 121 can also be connected to the reinforcement plate 120 by welding, bonding, or other methods. For example, the reinforcement plate 120 includes a plate body 122 having a through hole 123 formed therein, and the explosion-proof valve 121 is mounted within the through hole 123, as shown in Figures 6 to 10.

[0106] Continuing with Figures 9 and 10 , in some embodiments, a boss 124 is provided on the side of the reinforcing plate 120 facing the first plate. The boss 124 extends into the pressure relief vent 115 and is welded to the edge of the pressure relief vent 115. This facilitates positioning of the reinforcing plate 120 when connected to the first side plate 111. Furthermore, the welding of the boss 124 to the edge of the pressure relief vent 115 improves the sealing of the single cell 1000 and prevents electrolyte leakage.

[0107] Figure 11 is a view taken along arrow A of Figure 5 , Figure 12 is a cross-sectional view taken along line CC in Figure 11 , and Figure 13 is a partially enlarged view of point I in Figure 12 . For example, as shown in Figures 11 to 13 , the height of the boss 124 protruding from the reinforcing plate 120 can be equal to the thickness of the first side plate 111 , such that the end of the boss 124 away from the plate body 122 is flush with the side of the first side plate 111 away from the battery cell 200.

[0108] Figure 14 is a side view of the housing 110 according to an embodiment of the present application. As shown in Figure 14 , in some embodiments, the second side panel 112 includes a first plate 1121 connected to the third side panel 113 and a second plate 1122 connected to the fourth side panel 114. The first plate 1121 and the second plate 1122 are welded together to form the housing 110 into a closed cylindrical structure. The first side panel 111 is provided with a pressure relief vent 115 and other structures. Therefore, the weld is positioned on the second side panel 112, which is opposite the first side panel 111, to prevent the weld 1 from affecting the dimensional accuracy of the pressure relief vent 115.

[0109] The first plate 1121 and the second plate 1122 may have the same size or different sizes. For example, the first plate 1121 and the second plate 1122 have the same size, so that the housing 110 has a symmetrical structure.

[0110] The first plate 1121 and the second plate 1122 are welded to form a weld 1. Exemplarily, the first plate 1121 and the second plate 1122 are welded using a high-frequency welding process to improve production efficiency.

[0111] In some embodiments, the penetration depth of the weld 1 is greater than or equal to 0.2 mm, and / or the weld width of the weld 1 is greater than or equal to 0.3 mm, so that the housing 110 is not easily broken under the pressure of the battery cell 200 .

[0112] Please refer to Table 3. Based on the six types of single battery cells 1000 provided in Examples 7-12 above, the first plate 1121 and the second plate 1122 of the shell 110 are further fixed by welding, wherein S1 / S2 is equal to 0.8, and the penetration depth and width of the weld 1 on the shell 110 are 0.15 mm, 0.2 mm, 0.25 mm, 0.35 mm, 0.45 mm, and 0.5 mm, respectively. The first opening 110 a, the second opening 110 b, and the explosion-proof valve 121 of the shell 110 are sealed, and air is inflated into the interior of the shell 110 by a pneumatic loader to simulate the thermal runaway gas production process in the battery cell 200. The loaded air pressure is ≥1.2 MPa, and the shell 110 does not rupture or release pressure, and the test passes.

[0113] Table 3

[0114] As shown in Table 3, when the penetration depth and the weld width are greater than or equal to 0.2 mm and 0.5≤S1 / S2≤1, the test pass rate reaches 100%. When the penetration depth and the weld width are less than 0.2 mm, the test pass rate decreases slightly.

[0115] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A single cell, wherein, Comprising a housing, a reinforcing plate and an electric core, The housing includes a plurality of side plates, the plurality of side plates enclose a cavity, the electric core is installed in the cavity, the plurality of side plates include a first side plate, and the first side plate is provided with a pressure relief port which communicates with the cavity. The reinforcing plate is disposed in the cavity and is connected to the surface of the first side plate located in the cavity. The surface area of the first side plate located in the cavity is S2, and the surface area of the reinforcing plate facing the first side plate is S1, wherein 0.5 ≤ S1 / S2 ≤ 1.

2. The single cell according to claim 1, wherein, The reinforcing plate is welded to the first side plate. The thickness of the reinforcing plate is t1, and the thickness of the first side plate is t2, wherein 0.8 mm ≤ t1 + t2 ≤ 2.5 mm.

3. The single cell according to claim 2, wherein, 0.4 mm ≤ t1 ≤ 1.2 mm, 0.4 mm ≤ t2 ≤ 1.3 mm.

4. The single cell according to claim 2, wherein, 0.4 mm ≤ t2 ≤ 1.3 mm.

5. The single cell according to claim 2, wherein, 0.4 mm ≤ t1 ≤ 1.2 mm and 0.4 mm ≤ t2 ≤ 1.3 mm.

6. The single cell according to any one of claims 1 to 5, wherein, The reinforcing plate is provided with an explosion-proof valve, and the explosion-proof valve is disposed opposite to the pressure relief port.

7. The single cell according to any one of claims 1 to 5, wherein, The reinforcing plate includes one or more welding areas which are welded to the first side plate, and the welding areas surround the pressure relief port.

8. The single cell according to any one of claims 1 to 5, wherein, A boss is provided on the side of the reinforcing plate facing the first side plate, the boss extends into the pressure relief port, and the boss is welded to the edge of the pressure relief port.

9. The single cell according to claim 8, wherein, The housing further includes a second side plate, a third side plate and a fourth side plate. The second side plate is opposite to the first side plate, the third side plate is opposite to the fourth side plate, and the third side plate and the fourth side plate are located between the first side plate and the second side plate. The first side plate, the second side plate, the third side plate and the fourth side plate are of an integral plate structure and are bent to enclose the housing.

10. The single cell according to claim 9, wherein, The second side plate includes a first plate connected to the third side plate and a second plate connected to the fourth side plate. The first plate and the second plate are welded so that the housing has a cylindrical structure with both ends open.

11. The single cell according to claim 10, wherein, The first plate and the second plate are welded to form a weld seam.

12. The single cell according to claim 11, wherein, The penetration depth of the weld seam is greater than or equal to 0.2 mm.

13. The single cell according to claim 11, wherein, The width of the weld seam is greater than or equal to 0.3 mm.

14. The single cell according to claim 11, wherein, The penetration depth of the weld seam is greater than or equal to 0.2 mm and the width of the weld seam is greater than or equal to 0.3 mm.

15. A battery pack, wherein, Comprising a single cell according to any one of claims 1 to 14.

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