Battery cell, battery and electrical apparatus

Abstract

A battery cell (100), a battery (1000), and an electrical apparatus. The battery cell (100) comprises: an electrode assembly (20); and a casing (10), the casing (10) being used for accommodating the electrode assembly (20). The casing (10) is provided with a scoring groove (41) and a buffer groove (50), the scoring groove (41) defining a predetermined pressure relief area (401) which is opened when the battery cell (100) is subjected to pressure relief, and the buffer groove (50) being located on the side of the scoring groove (41) away from the geometric center of the predetermined pressure relief area (401).

Description

Battery cells, batteries and electrical devices Technical Field

[0001] The present application relates to the field of batteries, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a key factor in their development.

[0003] In order to ensure the safety performance of the battery cell, a pressure relief portion with a notched groove is usually provided on the battery cell. The pressure relief portion is used to release the pressure inside the battery cell when the battery cell reaches a predetermined condition. During the charging and discharging process of the battery cell, the electrode assembly will expand and deform, causing the outer shell accommodating the electrode assembly to swell and deform, which in turn makes the pressure relief portion provided on the outer shell easily damaged, reducing the reliability of the battery cell.

[0004] Summary of the Invention

[0005] In view of the above problems, the present application provides a battery cell, a battery and an electrical device, which can alleviate the problem of damage occurring at the notched groove during battery use.

[0006] In a first aspect, the present application provides a battery cell, comprising: an electrode assembly; and a shell, the shell being used to accommodate the electrode assembly, the shell being provided with a notched groove and a buffer groove, the notched groove defining a predetermined pressure relief zone that opens when the battery cell is depressurized, the buffer groove being located on a side of the notched groove away from the geometric center of the predetermined pressure relief zone.

[0007] In the technical solution of the embodiment of the present application, a buffer groove is provided on the outside of the notched groove, so that the outer shell can undergo a certain deformation at the buffer groove when the electrode assembly expands, so that the expansion force of the electrode assembly can be released at the buffer groove, reducing the force transmitted to the notched groove, thereby reducing the deformation amount at the notched groove, reducing the probability of the notched groove being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell.

[0008] In some embodiments, the scored groove and the buffer groove are located on the same side wall of the outer shell, with the buffer groove being located closer to the edge of the outer shell relative to the scored groove. In the above technical solution, the expansion force of the electrode assembly pulls on the first wall. By providing the buffer groove, the first wall can be stretched more at the buffer groove, thereby reducing the stretching at the scored groove, reducing the probability of the outer shell being damaged at the scored groove and causing leakage, thereby improving the service life and reliability of the battery cell.

[0009] In some embodiments, the housing includes a pressure relief portion, which is separately provided from the wall portion of the housing. The pressure relief portion includes the notched groove, and the buffer groove is provided on the pressure relief portion and is located on a side of the notched groove away from the geometric center of the predetermined pressure relief zone. The thickness of the pressure relief portion at the buffer groove is greater than the thickness of the pressure relief portion at the notched groove. In the above technical solution, the buffer groove is directly provided on the pressure relief portion, and the pressure relief portion is a component independent of the wall portion of the housing. The pressure relief portion can be produced separately and then assembled to the wall portion of the housing, which reduces production difficulty and improves efficiency.

[0010] In some embodiments, the electrode assembly includes at least one positive electrode sheet and at least one negative electrode sheet, and the at least one positive electrode sheet and the at least one negative electrode sheet are stacked to form a flat area, and at least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet are stacked along a first direction in the flat area, and the shell includes a first wall portion, and the first wall portion is located on one side of the electrode assembly in a second direction, and the second direction is the thickness direction of the first wall portion and is perpendicular to the first direction, and the first wall portion is provided with the notched groove and the buffer groove. In the above technical solution, the buffer groove is located between the notched groove and the outer edge of the first wall portion. When the electrode assembly expands, the expansion force acts on the shell to stretch the first wall portion. By providing the buffer groove, the first wall portion can have more stretching at the buffer groove, thereby reducing the stretching of the weak area, reducing the probability of the weak area being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell.

[0011] In some embodiments, the buffer groove includes a first buffer groove portion, which is located on one side of the scored groove in the first direction. In the above technical solution, when the electrode assembly expands, the first wall portion is subjected to a large pulling force in the first direction, which can be relieved to a certain extent at the first buffer groove portion, thereby effectively reducing the pulling force transmitted to the scored groove, lowering the probability of the scored groove being pulled and damaged, reducing the risk of leakage, and improving the service life and reliability of the battery cell.

[0012] In some embodiments, the maximum width of the predetermined pressure relief zone in the first direction is W1, and the maximum width of the first buffer groove in the first direction is W2, satisfying the condition 0.3≤W2 / W1≤1. In the above technical solution, the area of ​​the predetermined pressure relief zone can be increased, meeting exhaust requirements and improving the timeliness of the pressure relief portion's explosion. At the same time, the rigidity of the first wall portion at the first buffer groove portion is reduced. When the electrode assembly expands, the first wall portion at the first buffer groove portion deforms to some extent, allowing for a certain amount of relief of the expansion force. This, in turn, reduces stretching on the weak area, lowering the probability of the weak area being pulled and damaged, leading to leakage, and improving the service life and reliability of the battery cell.

[0013] In some embodiments, the maximum length of the predetermined pressure relief zone in the third direction is L1, and the maximum length of the first buffer groove in the third direction is L2, satisfying the following: L2 / L1 ≥ 1, and the third direction is perpendicular to the first direction and the second direction, respectively. In this technical solution, the pulling force applied to various locations throughout the predetermined pressure relief zone is reduced to a certain extent. The first buffer groove can buffer the weak areas in various locations, reducing the probability of the weak areas being damaged by pulling and leaking, thereby improving the service life and reliability of the battery cells.

[0014] In some embodiments, the thickness of the flat region in the first direction is W0, and the maximum width of the first buffer groove in the first direction is W2, satisfying 0.1≤W2 / W0≤0.3. In the above technical solution, while ensuring a certain energy density of the battery cell, the area of ​​the predetermined pressure relief zone can be increased to meet exhaust requirements and improve the timeliness of the pressure relief portion's explosion. Simultaneously, the stiffness of the first wall at the first buffer groove is reduced. When the electrode assembly expands, the first wall at the first buffer groove deforms to some extent, allowing for a certain release of the expansion force. This, in turn, reduces stretching on the weak zone, lowering the probability of the weak zone being pulled and damaged, leading to leakage, and thereby improving the service life and reliability of the battery cell.

[0015] In some embodiments, the buffer groove includes a second buffer groove portion, which is located on one side of the scored groove in a third direction, wherein the third direction is perpendicular to the first direction and the second direction. In the above technical solution, when the electrode assembly expands, the first wall portion is subjected to a certain pulling force in the third direction. By providing the second buffer groove portion, the pulling force can be relieved to a certain extent at the second buffer groove portion, thereby reducing the pulling force transmitted to the scored groove, reducing the probability of the scored groove being damaged by pulling, reducing the risk of leakage, and improving the service life and reliability of the battery cell.

[0016] In some embodiments, the housing includes a pressure relief portion, the notched groove is provided in the pressure relief portion, the pressure relief portion and the first wall portion are separately provided, the pressure relief portion is mounted on the first wall portion, and the buffer groove is located in the first wall portion. In the above technical solution, the pressure relief portion is a separate structural member, and by providing a buffer groove on the first wall portion, the first wall portion can have more stretching at the buffer groove, thereby reducing the stretching at the connection between the pressure relief portion and the first wall portion. The buffer groove can effectively buffer the connection between the pressure relief portion and the first wall portion, reducing the probability of the connection being pulled and damaged, resulting in leakage, while reducing the stretching at the notched groove, reducing the probability of the housing being pulled and damaged at the notched groove, resulting in leakage, and improving the service life and reliability of the battery cell.

[0017] In some embodiments, the pressure relief portion has a length direction, the maximum dimension of the pressure relief portion in the length direction is L0, at least a portion of the buffer groove extends along the length direction, and the maximum groove length of the buffer groove in the length direction is L2, -30mm≤L2-L0≤30mm. In the above technical solution, the buffer groove can effectively buffer the connection between the pressure relief portion and the first wall portion, reducing the probability of the connection being pulled and damaged, resulting in leakage, while also avoiding, to a certain extent, a transitional reduction in the structural strength of the first wall portion, reducing the probability of the first wall portion rupturing during testing or use.

[0018] In some embodiments, the minimum distance W between the edge of the buffer groove proximal to the pressure relief portion and the edge of the pressure relief portion satisfies the following conditions: 0.2 mm ≤ W ≤ 25 mm. In the above technical solution, by limiting W to within this range, the buffer groove provides a buffering effect at the connection between the pressure relief portion and the first wall, reducing the probability of the connection being damaged by pulling and causing leakage.

[0019] In some embodiments, the scored groove and the buffer groove are located on different side walls of the housing. In the above technical solution, by arranging the scored groove and the buffer groove on different side walls of the housing, the strength reduction of the wall portion with the scored groove can be avoided to a certain extent. At the same time, the buffer groove is provided on the other wall portion to release some expansion stress, thereby buffering the force applied to the scored groove, which is beneficial for reducing the probability of the scored groove being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell.

[0020] In some embodiments, the electrode assembly includes at least one positive electrode sheet and at least one negative electrode sheet, the at least one positive electrode sheet and the at least one negative electrode sheet being stacked to form a flat region, at least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet being stacked along a first direction in the flat region; the housing includes a first wall portion and two second walls connected to the first wall portion, the two second walls being located on either side of the electrode assembly along the first direction, the first wall portion being located on one side of the electrode assembly in a second direction, the second direction being the thickness direction of the first wall portion and being perpendicular to the first direction, the first wall portion being provided with the notched groove, and the second wall portion being provided with the buffer groove. In the above technical solution, when the electrode assembly expands, expansion force acts on the second wall portion and the first wall portion, and the expansion stress is likely to be concentrated at the buffer groove of the second wall portion, causing the second wall portion to deform at the buffer groove. Under a constant expansion force, the pulling force on the first wall portion can be reduced, thereby reducing the probability of the first wall portion being pulled and damaged at the notched groove, resulting in leakage, thereby improving the service life and reliability of the battery cell.

[0021] In some embodiments, the buffer groove is located at an end of the second wall portion proximal to the first wall portion. The buffer groove has an edge proximal to the first wall portion, and the minimum distance M between the edge and the inner wall surface of the first wall portion satisfies the following conditions: 0 ≤ M ≤ 5 mm, preferably 0 ≤ M ≤ 2 mm. In the above technical solution, the buffer groove can provide a certain buffering effect for the weak area, reducing the probability of the weak area being pulled and damaged, resulting in leakage.

[0022] In some embodiments, the maximum width of the buffer groove in the second direction is N, satisfying 3mm≤N≤6mm. In the above technical solution, by limiting the maximum width N of the buffer groove to the above range, the buffer groove can effectively buffer the scored groove, reducing the probability of the connection being pulled and damaged, resulting in leakage. At the same time, it can avoid a certain degree of excessive reduction in the structural strength of the second wall portion, reducing the probability of the second wall portion rupturing during testing or use.

[0023] In some embodiments, the buffer groove is located at one end of the second wall portion near the first wall portion. The buffer groove has an edge near the first wall portion, the minimum distance between the edge and the inner wall surface of the first wall portion is M, and the maximum groove width of the buffer groove in the second direction is N, satisfying: M = 0, and 5mm≤N≤6mm. In the above technical solution, the buffer groove can effectively buffer the scored groove, reducing the probability of the scored groove being pulled and damaged, resulting in leakage. At the same time, it can avoid a transitional decrease in the structural strength of the second wall portion to a certain extent, reducing the probability of the second wall portion rupturing during testing or use.

[0024] In some embodiments, the buffer groove is located at one end of the second wall portion near the first wall portion. The buffer groove has an edge near the first wall portion, the minimum distance between the edge and the inner wall surface of the first wall portion is M, and the maximum groove width of the buffer groove in the second direction is N, satisfying: 0<M≤2mm, and 3mm≤N≤4mm. In the above technical solution, the buffer groove can effectively buffer the scored groove, reducing the probability of the scored groove being pulled and damaged, resulting in leakage. At the same time, it avoids a certain degree of reduction in the structural strength of the second wall portion, reducing the probability of the second wall portion rupturing during testing or use.

[0025] In some embodiments, the buffer groove extends along a third direction, spaced from the edge of the second wall portion in the third direction, and the third direction is perpendicular to the first and second directions. This technical solution can, to a certain extent, prevent the end of the buffer groove from extending onto the adjacent wall portion, thereby affecting the strength of the connection between the second wall portion and the adjacent wall portion. This allows the buffer groove to provide a buffering effect on the scored groove while also improving the structural strength of the entire housing, thereby reducing the possibility of the housing breaking during testing or use.

[0026] In some embodiments, the maximum length of the buffer groove in the third direction is less than the maximum length of the electrode assembly in the third direction. In the above technical solution, the buffer groove not only provides a buffering effect on the scored groove, but also improves the structural strength of the second wall portion, thereby preventing the second wall portion from cracking during testing or use.

[0027] In some embodiments, the housing includes multiple walls and a pressure relief portion, wherein the pressure relief portion includes the notched groove, and at least one of the walls includes the buffer groove. In the above technical solution, when the electrode assembly expands, deformation of the housing is shared by the pressure relief portion and the walls of the housing. The first and second walls can deform to a certain extent at the buffer groove, thereby reducing deformation of the pressure relief portion, thereby reducing the risk of cracking at the pressure relief portion and improving the reliability of the battery cell.

[0028] In some embodiments, the buffer groove is provided on the inner and / or outer surface of the wall. In the above technical solution, the groove can be provided on a single surface of the wall of the shell to simplify the manufacturing process; alternatively, the groove can be provided on both sides of the shell wall to avoid a certain degree of reduction in the strength of the shell wall, while also improving the buffering effect of the buffer groove on the scored groove, reducing the probability of the pressure relief portion being pulled and damaged on rough surfaces, resulting in leakage, and improving the service life and reliability of the battery cell.

[0029] In some embodiments, the maximum depth of the buffer groove is H1, and the thickness of the wall of the housing where the notch is located is H0, satisfying the following: 25% ≤ H1 / H0 ≤ 97.5%; further, 40% ≤ H1 / H0 ≤ 80%; and preferably, 50% ≤ H1 / H0 ≤ 70%. In the above technical solution, by limiting the ratio H1 / H0, the wall of the housing can deform slightly at the buffer groove when the electrode assembly expands, thereby relieving the expansion force to a certain extent. This can reduce the stretching on the notch of the pressure relief portion, reduce the probability of the weak area being pulled and damaged, resulting in leakage, and improve the service life and reliability of the battery cell.

[0030] In some embodiments, the thickness of the wall portion of the housing where the notch is located is H0, satisfying the following relationship: 0.4 mm ≤ H0 ≤ 2 mm. In this technical solution, the buffer groove effectively cushions the notch, reducing the likelihood of the notch being pulled and damaged, leading to leakage. This also prevents, to a certain extent, a significant decrease in the structural strength of the housing, reducing the likelihood of the housing cracking during testing or use.

[0031] In some embodiments, the minimum thickness of the housing at the buffer groove is H2, satisfying the following: 0.05mm≤H2≤1.5mm. In the above technical solution, by limiting H2, the housing has appropriate strength at the buffer groove, which can not only prevent the housing from cracking in scenarios such as falling, but also allow for some deformation when the electrode assembly expands, thereby buffering the force acting at the notch groove, reducing the probability of the weak area at the notch groove being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell.

[0032] In some embodiments, a transition zone is provided on the periphery of the buffer groove, the thickness of which gradually increases as it moves away from the center of the buffer groove. This technical solution prevents the thickness of the outer shell from suddenly decreasing at the buffer groove, to a certain extent preventing damage to the outer shell due to stress concentration at the buffer groove, thereby improving the reliability of the battery cell. Furthermore, the buffer groove can be integrally injection-molded with the outer shell using a mold, simplifying the manufacturing process of the buffer groove.

[0033] In some embodiments, the width of the transition zone, along a direction away from the center of the buffer slot, is 0, satisfying the following: 3mm≤0≤5mm. In the above technical solution, limiting the width of the transition zone not only facilitates the integral injection molding of the buffer slot and the housing, but also improves the strength of the housing, reduces the probability of the housing rupturing at the buffer slot, and improves the reliability and service life of the battery cell.

[0034] In some embodiments, the housing includes a pressure relief portion having the notched groove, and the pressure relief portion is integrally formed with the wall of the housing. In the above technical solution, by integrally forming the pressure relief portion with the wall of the housing, the reliability of the pressure relief portion can be improved, the connection process between the pressure relief portion and the wall of the housing is eliminated, and the production cost of the battery cell can be reduced.

[0035] In some embodiments, the housing includes a pressure relief portion having the notched groove, the pressure relief portion being separately disposed from the wall portion of the housing and being mounted on the wall portion of the housing. In the above technical solution, the pressure relief portion is a component independent of the wall portion of the housing. The pressure relief portion and the wall portion of the housing can be manufactured separately and then assembled, which reduces production difficulty and improves efficiency.

[0036] In some embodiments, the buffer grooves are symmetrically arranged along the geometric center of the housing. In the above technical solution, the overall housing forms a symmetrical structure, which not only facilitates the manufacture of the buffer grooves, but also enables the buffer grooves to provide the same buffering effect to the notched grooves at all locations, reducing the probability of localized tearing and breakage of the notched grooves, thereby improving the reliability of the entire battery cell.

[0037] In some embodiments, the buffer tank is integrally formed on the housing. In the above technical solution, the manufacturing process of the buffer tank can be simplified, thereby simplifying the manufacturing process of the battery cell.

[0038] In some embodiments, the buffer groove is formed by a grooving process. In the above technical solution, the buffer groove is formed on the inner surface and / or outer surface of the shell by grooving the shell. The grooving can be performed by laser etching, chemical etching, or machining, which is convenient and facilitates precise control of the size of the buffer groove.

[0039] In some embodiments, the housing comprises: a shell and an end cap, wherein at least one side of the shell has an opening, the end cap is connected to the shell and is used to close the opening, and the scored groove is provided in the shell. In the above technical solution, by providing the scored groove on the shell, the structure of the end cap can be simplified, and the distance between the scored groove and the main body of the electrode assembly can be shortened. This can further shorten the path of the discharge medium flowing to the scored groove during pressure relief, shorten the time it takes for the discharge medium to reach the scored groove, improve the timeliness of pressure relief of the battery cell, and thus effectively improve the reliability of the battery cell.

[0040] In some embodiments, the housing has openings on opposite sides, and the two end caps are used to close the openings on the corresponding sides. In the above technical solution, by providing two openings on the housing, it is possible to facilitate the manufacturing and molding of the housing, and at the same time facilitate the extension of the electrode tabs from both ends of the electrode assembly, thereby facilitating the separation of the two electrical connections and reducing the risk of short circuits in the battery cells.

[0041] In some embodiments, the end cap is provided with an electrical connection portion, the electrical connection portion being electrically connected to the positive electrode plate, or the electrical connection portion being electrically connected to the negative electrode plate. In the above technical solution, electrical energy of the battery cell can be input or output.

[0042] In some embodiments, the housing has a first wall portion, the first wall portion being provided with the notched groove, the first wall portion being used to support the electrode assembly and being located below the electrode assembly. In the above technical solution, the notched groove may be provided at the bottom of the battery cell, and the bottom of the battery cell may be provided with an exhaust channel, which may be connected to a predetermined pressure relief zone so that high-temperature and high-pressure flue gas can be discharged through the bottom into the exhaust channel and then to the outside world when thermal runaway of the battery cell occurs.

[0043] In some embodiments, the predetermined pressure relief zone has a predetermined opening boundary, which is defined by the outer edge of the orthographic projection of at least a portion of the scored groove in the depth direction of the scored groove; or defined by the line connecting multiple ends of the scored groove; or defined by the line connecting multiple ends of the scored groove and the outer edge of the orthographic projection of at least a portion of the scored groove in the depth direction of the scored groove. In the above technical solution, the use of the scored groove structure described above facilitates rapid pressure relief at the pressure relief portion.

[0044] In a second aspect, the present application provides a battery comprising the battery cell in the above embodiment.

[0045] In a third aspect, the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0046] 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

[0047] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0048] FIG1 is a schematic diagram of an electric device in the related art;

[0049] FIG2 is a schematic diagram of a battery in the related art;

[0050] FIG3 is a schematic diagram of a battery cell provided in some embodiments of the present application;

[0051] FIG4 is an exploded view of a battery cell provided in some embodiments of the present application;

[0052] FIG5 is a schematic diagram of an electrode assembly provided in some embodiments of the present application;

[0053] FIG6 is a schematic diagram of electrode assemblies provided in some other embodiments of the present application;

[0054] FIG7 is a schematic diagram of a pressure relief portion provided in some embodiments of the present application;

[0055] FIG8 is a cross-sectional view along line AA in FIG7;

[0056] FIG9 is a cross-sectional view along line BB in FIG7 ;

[0057] FIG10 is an enlarged view of circle C in FIG9 ;

[0058] FIG11 is a schematic diagram of a housing provided in some embodiments of the present application;

[0059] FIG12 is a cross-sectional view of a housing provided in some embodiments of the present application;

[0060] FIG13 is an enlarged view of circle D in FIG12 ;

[0061] FIG14 is a partial cross-sectional view of a housing provided in some embodiments of the present application;

[0062] FIG15 is an enlarged view of circle E in FIG14 provided in some embodiments;

[0063] FIG16 is a partial cross-sectional view of a housing provided in some embodiments of the present application;

[0064] FIG17 is a schematic diagram of a housing provided in some embodiments of the present application;

[0065] FIG18 is a cross-sectional view of the structure shown in FIG17;

[0066] FIG19 is an enlarged view of circle F in FIG18 ;

[0067] FIG20 is a schematic diagram of a housing provided in some embodiments of the present application;

[0068] FIG21 is an exploded view of a battery cell provided in some embodiments of the present application;

[0069] FIG22 is a bottom view of the structure shown in FIG21;

[0070] FIG23 is an exploded view of a battery cell provided in some embodiments of the present application;

[0071] FIG24 is a bottom view of the structure shown in FIG23;

[0072] FIG25 is a cross-sectional view of the battery cell shown in FIG23;

[0073] FIG26 is an enlarged view of circle G in FIG25 ;

[0074] FIG27 is a schematic diagram of a battery cell provided by some embodiments of the present application;

[0075] FIG28 is a partial schematic diagram of a housing provided in some embodiments of the present application;

[0076] FIG29 is a top view of a housing provided in some embodiments of the present application;

[0077] FIG30 is a cross-sectional view taken along line HH in FIG29 provided in some embodiments;

[0078] FIG31 is a cross-sectional view along line II in FIG29 provided in some embodiments;

[0079] FIG32 is an enlarged view of circle J in FIG31 ;

[0080] FIG33 is a cross-sectional view taken along line HH in FIG29 provided in accordance with some other embodiments;

[0081] FIG34 is a cross-sectional view taken along line II in FIG29 provided in some other embodiments;

[0082] FIG35 is an enlarged view of circle K in FIG34 ;

[0083] FIG36 is a schematic diagram of a housing provided in some embodiments of the present application;

[0084] FIG37 is a cross-sectional view of the housing shown in FIG36;

[0085] FIG38 is an enlarged view of circle L in FIG37;

[0086] FIG39 is a schematic diagram of a first wall portion provided in some embodiments of the present application;

[0087] FIG40 is a cross-sectional view taken along line MM in FIG39 provided in some embodiments;

[0088] FIG41 is a cross-sectional view taken along line MM in FIG39 provided in accordance with some other embodiments;

[0089] FIG42 is a schematic diagram of a pressure relief portion provided in some embodiments of the present application;

[0090] FIG43 is a schematic diagram of a pressure relief portion provided in some other embodiments of the present application;

[0091] Figure 44 is a schematic diagram of a pressure relief portion provided in some other embodiments of the present application.

[0092] Figure markings: battery 1000, vehicle 2000, box 200, first part 210, first part 220, battery cell 100, shell 10, shell 101, end cover 102, first wall 11, through hole 111, second wall 12, electrode assembly 20, positive electrode sheet 21, negative electrode sheet 22, straight area 23, turning area 24, electrical connection part 30, pressure relief part 40, predetermined pressure relief area 401, notched groove 41, first arc segment 411, first straight line segment 412, second straight line segment 413, third straight line segment 414, arc segment 415, fourth straight line segment 416, fifth straight line segment 417, sixth straight line segment 418, seventh straight line segment 419 (flip notch 419), buffer groove 50, first buffer groove portion 50a, second buffer groove portion 50b, transition zone 51, first direction F1, second direction F2, third direction F3. DETAILED DESCRIPTION

[0093] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are 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.

[0094] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0095] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0096] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0097] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0098] The term "plurality" used in this application refers to two or more (including two).

[0099] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0100] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0101] The battery mentioned in the embodiments of the present application may include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in hybrid through a busbar.

[0102] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0103] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0104] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0105] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0106] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, the safety performance of the battery also needs to be considered.

[0107] In a battery cell, to ensure the safety performance of the battery cell, a pressure relief portion may be provided on the outer shell of the battery cell. When the battery cell experiences thermal runaway, the pressure inside the battery cell is released through the pressure relief portion to improve the safety of the battery cell.

[0108] During the charging and discharging process of the battery cell, the electrode assembly will expand, causing the shell to swell and deform, and the pressure relief part is arranged on the shell, especially some pressure relief parts are arranged on the wall on the side closer to the electrode assembly. The expansion of the electrode assembly will cause the wall where the pressure relief part is located to deform, thereby pulling the notch of the pressure relief part, causing the pressure relief part to be damaged at the notch and then leaking, etc. As a result, the pressure relief part will be destroyed when the pressure inside the battery cell does not reach the detonation pressure of the pressure relief part, causing the pressure relief part to fail and the reliability of the pressure relief part is low.

[0109] In view of this, an embodiment of the present application provides a battery cell, comprising: an electrode assembly; a shell, the shell being used to accommodate the electrode assembly, the shell being provided with a notched groove and a buffer groove, the notched groove defining a predetermined pressure relief area that opens when the battery cell is depressurized, and the buffer groove being located on a side of the notched groove away from the geometric center of the predetermined pressure relief area.

[0110] In such a battery cell, by providing a buffer groove on the outside of the scored groove, the outer shell can undergo a certain deformation at the buffer groove when the electrode assembly expands, so that the expansion force of the electrode assembly can be released at the buffer groove, reducing the force transmitted to the scored groove, thereby reducing the deformation at the scored groove, reducing the probability of the scored groove being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell.

[0111] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0112] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0113] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0114] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle 2000 provided in some embodiments of the present application. A battery 1000 is disposed within vehicle 2000. Battery 1000 can be located at the bottom, front, or rear of vehicle 2000. Battery 1000 can be used to power vehicle 2000. For example, battery 1000 can serve as the operating power source of vehicle 2000.

[0115] The vehicle 2000 may further include a controller and a motor. The controller is used to control the battery 1000 to power the motor, for example, to meet the power requirements of the vehicle 2000 during starting, navigation, and driving.

[0116] In some embodiments of the present application, the battery 1000 can not only serve as the operating power source of the vehicle 2000, but also serve as the driving power source of the vehicle 2000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 2000.

[0117] Please refer to Figure 2, which is an exploded view of a battery 1000 provided in some embodiments of the present application. The battery 1000 includes a battery cell 100 and a housing 200, wherein the housing 200 is used to accommodate the battery cell 100.

[0118] The housing 200 is a component that houses the battery cells 100 and provides storage space for the battery cells 100. The housing 200 can have various structures. In some embodiments, the housing 200 can include a first portion 210 and a second portion 220, which overlap to define a storage space for the battery cells 100. The first portion 210 and the second portion 220 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first portion 210 can be a hollow structure with one side open, and the second portion 220 can be a hollow structure with one side open. The open side of the second portion 220 overlaps the open side of the first portion 210, forming the housing 200 with storage space. Alternatively, the first portion 210 can be a hollow structure with one side open, and the second portion 220 can be a plate-like structure. The second portion 220 overlaps the open side of the first portion 210, forming the housing 200 with storage space. As an example, the battery cell 100 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell 100 of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, and a polygonal battery such as a hexagonal battery, etc. There is no special limitation in this application.

[0119] In the battery 1000, there can be one or more battery cells 100. If there are multiple battery cells 100, the multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. Multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection to form a battery module, which is then connected in series, parallel, or in a hybrid connection to form a whole and housed within the housing 200. Alternatively, all battery cells 100 can be directly connected in series, parallel, or in a hybrid connection, and then the whole battery module 100 can be housed within the housing 200.

[0120] 3 and 4 , FIG3 is a schematic diagram of a battery cell 100 provided in some embodiments of the present application; FIG4 is an exploded view of a battery cell 100 provided in some embodiments of the present application. The battery cell 100 may include a housing 100 and an electrode assembly 20 .

[0121] The housing 10 is used to house the electrode assembly 20 and other components such as the electrolyte. The housing 10 may be a steel shell, an aluminum shell, a plastic shell (e.g., polypropylene), a composite metal shell (e.g., a copper-aluminum composite shell), or an aluminum-plastic film. For example, the housing 10 may include a shell 101 and an end cap 102.

[0122] The housing 101 may be a hollow structure with an opening at one end, or may be a hollow structure with openings at two opposite ends. The housing 101 may be made of a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, and the like.

[0123] The end cap 102 is a component that closes the opening of the shell 101 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 102 and the shell 101 together define a storage space for accommodating the electrode assembly 20, electrolyte, and other components. The end cap 102 can be connected to the shell 101 by welding or crimping to close the opening of the shell 101. The shape of the end cap 102 can be adapted to the shape of the shell 10. For example, the shell 101 is a rectangular parallelepiped structure, and the end cap 102 is a rectangular plate structure adapted to the shell 10. The material of the end cap 102 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0124] In the battery cell 10, there can be one or two end caps 102. In embodiments where the housing 101 is a hollow structure with openings at both ends, two end caps 102 can be provided. The two end caps 102 respectively close the two openings of the housing 101, and the two end caps 102 and the housing 101 together define a storage space. In embodiments where the housing 101 is a hollow structure with an opening at one end, there can be one end cap 102 provided. The end cap 102 closes the opening at one end of the housing 101, and the end cap 102 and the housing 101 together define a storage space.

[0125] The electrode assembly 20 includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell 100, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0126] In some embodiments, the positive electrode may be a positive electrode sheet 21 . The positive electrode sheet 22 may include a positive electrode current collector and a positive electrode active material region disposed on at least one surface of the positive electrode current collector. The positive electrode active material region has a positive electrode active material.

[0127] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material region is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0128] In some embodiments, the negative electrode may be a negative electrode sheet 22 , which may include a negative electrode current collector and a negative electrode active material region disposed on at least one surface of the negative electrode current collector.

[0129] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material region is provided on either one or both of the two facing surfaces of the negative electrode current collector.

[0130] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0131] In some embodiments, the electrode assembly 20 further includes a separator disposed between the positive electrode and the negative electrode.

[0132] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0133] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0134] In some embodiments, the battery cell 100 further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte may be selected based on needs. The electrolyte may be liquid, gel, or solid.

[0135] In some embodiments, the electrode assembly 20 is a wound structure in which the positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0136] In some embodiments, the electrode assembly 20 is a laminated structure.

[0137] As an example, a plurality of positive electrode sheets 21 and a plurality of negative electrode sheets 22 may be provided, and the plurality of positive electrode sheets 21 and the plurality of negative electrode sheets 22 may be alternately stacked.

[0138] As an example, a plurality of positive electrode sheets 21 may be provided, and the negative electrode sheet 22 may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0139] As an example, the positive electrode sheet 21 and the negative electrode sheet 22 are both folded to form a plurality of stacked folded segments. As an example, multiple separators may be provided, each disposed between any adjacent positive electrode sheets or negative electrode sheets. As an example, the separator may be provided continuously, folded or wound between any adjacent positive electrode sheets or negative electrode sheets.

[0140] In some embodiments, the shape of the electrode assembly 20 can be flat or polygonal.

[0141] In some embodiments, the electrode assembly 20 is provided with tabs, which can conduct current from the electrode assembly 20. The tabs include a positive tab and a negative tab.

[0142] The battery cell 100 may further include an electrical connector, which may be disposed on the housing 10 and is configured to electrically connect to the tabs of the electrode assembly 20 to output electrical energy from the battery cell 10. The electrical connector and the tabs may be directly connected, for example, by direct welding. The electrical connector and the tabs may also be indirectly connected, for example, through a current collecting member. The current collecting member may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0143] As shown in Figures 3 and 4, taking the shell 101 as an example of a hollow structure with an opening at one end, two electrical connection parts can be set on the end cover 102, and the two electrical connection parts are respectively a positive electrical connection part and a negative electrical connection part. The positive electrical connection part is electrically connected to the positive electrode ear, and the negative electrical connection part is electrically connected to the negative electrode ear.

[0144] Please refer to Figures 5 and 6. Figure 5 is a schematic diagram of an electrode assembly 20 provided in some embodiments of the present application; Figure 6 is a schematic diagram of an electrode assembly 20 provided in other embodiments of the present application. The electrode assembly 20 includes a positive electrode sheet 21 and a negative electrode sheet 22. The positive electrode sheet 21 includes a positive electrode body and a positive electrode tab. The positive electrode tab is extended from one end of the positive electrode body. Most of the positive electrode tab is not coated with positive electrode active material. Most of the positive electrode body is coated with positive electrode active material. The negative electrode sheet 22 includes a negative electrode body and a negative electrode tab. The negative electrode tab is extended from one end of the negative electrode body. Most of the negative electrode tab is not coated with negative electrode active material. Most of the negative electrode body is coated with negative electrode active material. The positive electrode body and the negative electrode body constitute the main body of the electrode assembly.

[0145] As shown in FIG. 5 , the electrode assembly 20 includes a plurality of electrode sheets arranged in a wound manner. The electrode assembly 20 includes a straight region 23 and a turning region 24 connected to ends of the straight region 23 .

[0146] A plurality of electrode sheets arranged in a wound manner, namely the positive electrode sheet 21 and the negative electrode sheet 22 are stacked and wound around a set axis to form an electrode assembly 20. The straight area 23 refers to the portion of the electrode sheet extending along the plane after winding; the turning area 24 refers to the portion of the electrode sheet extending along the arc surface after winding. For example, as shown in FIG5 , the portion between the front side surface and the rear side surface of the electrode assembly 20 is formed as the straight area 23. The extension direction of the electrode sheet in the straight area 23 is the length direction of the straight area 23. As shown in FIG5 , the thickness dimension of the straight area 23 in the front-to-back direction is W0, and the left and right ends of the straight area 23 are the turning areas 24.

[0147] As shown in FIG. 6 , the electrode assembly 120 includes a plurality of electrode sheets arranged in a stacked manner, and the electrode assembly 20 has a flat region 23 .

[0148] A plurality of stacked pole pieces, such as at least one positive pole piece 21 and at least one negative pole piece 22, are stacked to form an electrode assembly 20. The straight area 23 is formed by stacking at least a portion of the positive pole piece 21 and the negative pole piece 22, or can be formed by stacking at least a portion of the positive pole piece 21 and the negative pole piece 22. The extension direction of the pole piece in the straight area 23 is the length direction of the straight area 23. As shown in FIG6 , the thickness dimension of the straight area 23 in the front-to-back direction is W0.

[0149] Please refer to Figures 7 to 38. According to an embodiment of the present application, the battery cell 100 includes: an electrode assembly 20 and a shell 10. The shell 10 is used to accommodate the electrode assembly 20. The shell 10 is provided with a notched groove 41 and a buffer groove 50. The notched groove 41 defines a predetermined pressure relief area 401 that opens when the battery cell 100 is depressurized. The buffer groove 50 is located on a side of the notched groove 41 away from the geometric center of the predetermined pressure relief area 401.

[0150] The outer shell 10 is the outermost structural component of the battery cell 100 , and contains the electrode assembly 20 and electrolyte.

[0151] The electrode assembly 20 is disposed in the housing 10 . There may be one electrode assembly 20 or multiple electrode assemblies 20 in the housing 10 . Each electrode assembly 20 includes at least one positive electrode sheet 21 and at least one negative electrode sheet 22 .

[0152] The shell 10 is provided with a notched groove 41, which can be set on the wall of the shell 10, or on a structural member installed on the wall of the shell 10. The shell 10 forms a weak area at the notched groove 41, and the notched groove 41 defines a predetermined pressure relief area 401. The predetermined pressure relief area 401 is used to release the internal pressure of the battery cell 100 when the internal pressure of the battery cell 100 reaches a threshold, that is, the discharge medium inside the battery cell 100 can be discharged through the predetermined pressure relief area 401 to achieve the purpose of pressure relief. The threshold design varies according to different design requirements, and the threshold may depend on one or more materials of the positive electrode sheet 21, the negative electrode sheet 22, the electrolyte and the separator in the battery cell 100.

[0153] In which, the predetermined pressure relief area 401 has a predetermined opening boundary, and the predetermined opening boundary is surrounded by the outer edge of the positive projection of at least a part of the scored groove 41 in the second direction F2; or the predetermined opening boundary is surrounded by the connecting line between multiple ends of the scored groove 41; or the predetermined opening boundary is jointly surrounded by the connecting line between multiple ends of the scored groove 41 and the outer edge of the positive projection of at least a part of the scored groove 41 in the second direction F2.

[0154] The shell 10 is provided with a buffer groove 50, which is located on the side of the notched groove 41 away from the geometric center of the predetermined pressure relief area 401, so that the buffer groove 50 is located on the outside of the notched groove 41, and the buffer groove 50 is located outside the predetermined pressure relief area 401. By arranging the buffer groove 50 on the shell 10, that is, the shell 10 is thinned at the position of the buffer groove 50, the structural strength of the shell 10 at this position is reduced, so that the shell 10 is easy to deform at this position. When the electrode assembly 20 expands, the expansion force acts on the shell 10 to deform the shell 10. Since the shell 10 is more likely to deform at the corresponding position of the buffer groove 50, the expansion force of the electrode assembly 20 can be released to a certain extent at the buffer groove 50, thereby reducing the force transmitted to the notched groove 41, reducing the pulling force on the shell 10 at the notched groove 41, reducing the probability of the shell 10 being pulled and damaged at the notched groove 41, and reducing the risk of leakage.

[0155] In some examples, the cross-sectional shape of the buffer groove 50 can be at least one of a triangle, a rectangle, a square, a semicircle, a circle, an ellipse, and an inverted trapezoid; the buffer groove 50 can be arranged on the inner surface of the shell 10, or on the outer surface of the shell 10, or the buffer groove 50 can be arranged on the inner surface and the outer surface of the shell 10 respectively, and the buffer groove 50 can be arranged symmetrically along the center of the shell 10, or asymmetrically.

[0156] In the technical solution of the embodiment of the present application, a buffer groove 50 is provided on the outside of the notched groove 41, so that when the electrode assembly 20 expands, the outer shell 10 can undergo a certain deformation at the buffer groove 50, so that the expansion force of the electrode assembly 20 can be released to a certain extent at the buffer groove 50, reducing the force transmitted to the notched groove 41, thereby reducing the deformation of the outer shell 10 at the notched groove 41, reducing the probability of the outer shell 10 being pulled and damaged at the notched groove 41, and causing leakage, thereby improving the service life and reliability of the battery cell 100.

[0157] 7 to 27 , in some embodiments, the notched groove 41 and the buffer groove 50 are located on the same side wall of the housing 10 , and the buffer groove 50 is disposed closer to the edge of the housing 10 relative to the notched groove 41 .

[0158] As shown in Figures 7 to 27, the shell 10 has a first wall portion 11, and the first wall portion 11 has a notch groove 41 and a buffer groove 50. The buffer groove 50 is located between the notch groove 41 and the outer edge of the shell 10. When the electrode assembly 20 expands, the expansion force acts on the shell 10 to stretch the first wall portion 11. For an electrode assembly 20 of a certain size, the expansion force of the electrode assembly 20 pulls the first wall portion 11, so that the total stretching length of the first wall portion 11 is constant. By providing the buffer groove 50, the first wall portion 11 can have more stretching at the buffer groove 50, thereby reducing the stretching at the notch groove 41, reducing the probability of the shell 10 being pulled and damaged at the notch groove 41, and causing leakage, thereby improving the service life and reliability of the battery cell 100.

[0159] Referring to Figures 7 to 10, Figure 7 is a schematic diagram of the pressure relief portion provided in some embodiments of the present application; Figure 8 is a sectional view along line AA in Figure 7; Figure 9 is a sectional view along line BB in Figure 7; Figure 10 is an enlarged view of circle C in Figure 9; as shown in Figure 7, in some embodiments, the shell 10 includes a pressure relief portion 40, which is separately arranged from the wall portion of the shell 10, and the pressure relief portion 40 has a notched groove 41, and a buffer groove 50 is provided on the pressure relief portion 40 and is located on the side of the notched groove 41 away from the geometric center of the predetermined pressure relief area 401, and the thickness of the pressure relief portion 40 at the buffer groove 50 is greater than the thickness of the pressure relief portion 40 at the notched groove 41.

[0160] As shown in Figures 21 and 23, the housing 10 includes a pressure relief portion 40 and multiple wall portions, the multiple wall portions include a first wall portion 11 having a through hole 111, and the pressure relief portion 40 is installed in the through hole 111 of the first wall portion 11. When the internal pressure of the battery cell 100 reaches a threshold value, the pressure relief portion 40 opens at least part of the through hole 111, and the discharge medium inside the battery cell 100 is discharged through the through hole 111 to release the pressure inside the battery cell 100.

[0161] As shown in Figures 7 to 10, the pressure relief portion 40 is provided with a notched groove 41, which defines a predetermined pressure relief area 401. When the internal pressure of the battery cell 100 reaches a threshold value, the pressure relief portion 40 is at least partially destroyed, and the predetermined pressure relief area 401 is connected to at least part of the through hole 111 to release the pressure inside the battery cell 100.

[0162] As shown in Figures 7 to 10, the pressure relief portion 40 is provided with a buffer groove 50, which is located on the side of the notched groove 41 away from the geometric center of the predetermined pressure relief area 401, and the buffer groove 50 is located between the notched groove 41 and the outer edge of the pressure relief portion 40. When the electrode assembly 20 expands, the expansion force acts on the shell 10 to stretch the first wall portion 11, thereby pulling the pressure relief portion 40. By providing the buffer groove 50 on the pressure relief portion 40, the pressure relief portion 40 can have more stretching at the buffer groove 50, and the expansion force of the electrode assembly 20 can be released to a certain extent at the buffer groove 50, reducing the force transmitted to the notched groove 41, thereby reducing the tensile deformation of the notched groove 41, reducing the probability of the notched groove 41 being pulled and damaged, resulting in leakage, and to a certain extent avoiding the rupture of the pressure relief portion 40 during normal use of the battery cell 100, thereby improving the service life and reliability of the battery cell 100.

[0163] In addition, the buffer groove 50 is directly arranged on the pressure relief part 40. The pressure relief part 40 is a component independent of the wall of the shell 10. The pressure relief part 40 can be produced separately and then assembled to the wall of the shell 10. The production difficulty is low and the efficiency is high.

[0164] Referring to Figures 4-6 and 11-27, in some embodiments, the electrode assembly 20 includes at least one positive electrode sheet 21 and at least one negative electrode sheet 22, and the at least one positive electrode sheet 21 and the at least one negative electrode sheet 22 are stacked to form a straight area 23. At least a portion of the positive electrode sheet 21 and at least a portion of the negative electrode sheet 22 are stacked in the straight area 23 along a first direction F1. The outer shell 10 includes a first wall portion 11, and the first wall portion 11 is located on one side of the electrode assembly 20 in the second direction F2. The second direction F2 is the thickness direction of the first wall portion 11 and is perpendicular to the first direction F1. The first wall portion 11 is provided with a notch groove 41 and a buffer groove 50.

[0165] The electrode assembly 20 can be a laminated type, that is, multiple pole pieces of the electrode assembly 20 are stacked, and the pole pieces are stacked to form a flat area 23. In the flat area 23, at least a portion of the positive pole piece 21 and the negative pole piece 22 are stacked along the first direction F1, or at least a portion of the positive pole piece 21 and the negative pole piece 22 are stacked along the first direction F1. Therefore, the expansion deformation of the electrode assembly 20 is particularly obvious in the first direction F1.

[0166] The electrode assembly 20 can also be of a wound type. The positive electrode sheet 21 and the negative electrode sheet 22 of the electrode assembly 20 are stacked with the isolation member and then wound to form a straight area 23. In the straight area 23, part of the positive electrode sheet 21 and part of the negative electrode sheet 22 are stacked along the first direction F1. For example, after winding, each layer of the positive electrode sheet 21 and each layer of the negative electrode sheet 22 can be penetrated by an axis extending along the first direction F1, so that the expansion deformation of the electrode assembly 20 is particularly obvious in the first direction F1.

[0167] As shown in FIG. 11 and FIG. 12 , the first direction F1 is the front-rear direction, and the second direction F2 is the up-down direction.

[0168] The shell 10 includes a first wall portion 11, which is located on one side of the electrode assembly 20 in the second direction F2. The second direction F2 is perpendicular to the first direction F1. The thickness direction of the first wall portion 11 is the second direction F2. The first wall portion 11 is provided with a notch groove 41 and a buffer groove 50.

[0169] Among them, as shown in Figure 11, the scoring groove 41 can be integrally formed on the first wall portion 11, and the first wall portion 11 forms a weak area at the scoring groove 41, or as shown in Figures 21-26, the scoring groove 41 can be formed on the pressure relief portion 40, and the pressure relief portion 40 is installed on the first wall portion 11, and the pressure relief portion 40 forms a weak area at the scoring groove 41.

[0170] The buffer groove 50 is located between the notched groove 41 and the outer edge of the first wall portion 11. When the electrode assembly 20 expands, the expansion force acts on the outer shell 10 to stretch the first wall portion 11. By providing the buffer groove 50, the first wall portion 11 can have more stretching at the buffer groove 50, thereby reducing the stretching of the weak area, reducing the probability of the weak area being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0171] Referring to Figures 11-20, Figure 11 is a schematic diagram of a shell provided in some embodiments of the present application; Figure 12 is a cross-sectional view of a shell provided in some embodiments of the present application; Figure 13 is an enlarged view of circled D in Figure 12; Figure 14 is a partial cross-sectional view of a shell provided in some embodiments of the present application; Figure 15 is an enlarged view of circled E in Figure 14 provided in some embodiments; Figure 16 is a partial cross-sectional view of a shell provided in some embodiments of the present application; Figure 17 is a schematic diagram of a shell provided in some embodiments of the present application; Figure 18 is a cross-sectional view of the structure shown in Figure 17; Figure 19 is an enlarged view of circled F in Figure 18; Figure 20 is a schematic diagram of a shell provided in some embodiments of the present application; in some embodiments, the buffer groove 50 includes a first buffer groove portion 50a, and the first buffer groove portion 50a is located on one side of the notch groove 41 in the first direction F1.

[0172] As shown in Figures 13 and 15, in some examples, in the first direction F1, a first buffer groove portion 50a is provided on one side of the notched groove 41, as shown in Figures 16 to 19. In other examples, a plurality of first buffer groove portions 50a are provided on one side of the notched groove 41. The plurality of first buffer groove portions 50a can be arranged at intervals along the first direction. The plurality of first buffer groove portions 50a can be located on the lower surface of the first wall portion 11 or on the upper surface of the first wall portion 11. The first buffer groove portions 50a can also be respectively provided on the lower surface and the upper surface of the first wall portion 11. The first buffer groove portions 50a on the lower surface and the first buffer groove portions 50a on the upper surface of the first wall portion 11 can be arranged relative to each other in the upper and lower directions, or can be staggered.

[0173] As shown in Figure 14, the shell 10 also includes two second wall portions 12, which are located on both sides of the electrode assembly 20 in the first direction F1. Most of the expansion of the electrode assembly 20 will act on the second wall portion 12. When the electrode assembly 20 expands, the second wall portion 12 is pulled and deformed, and the second wall portion 12 pulls the first wall portion 11, so that the first wall portion 11 is subjected to a larger pulling force in the front-to-back direction, that is, the influence of the electrode assembly 20 on the first wall portion 11 in the front-to-back direction is less than the influence of the electrode assembly 20 on the first wall portion 11 in the left-to-right direction.

[0174] As shown in Figures 14 and 15, the first direction F1 extends along the front-to-back direction, and the first buffer groove portion 50a is located on the front and rear sides of the notched groove 41. When the electrode assembly 20 expands, the first wall portion 11 is subjected to a large pulling force in the front-to-back direction, which can be released to a certain extent at the first buffer groove portion 50a, thereby effectively reducing the pulling force transmitted to the notched groove 41, reducing the probability of the notched groove 41 being pulled and damaged, reducing the risk of leakage, and improving the service life and reliability of the battery cell 100.

[0175] As shown in FIG. 11 , in some embodiments, the maximum width of the predetermined pressure relief area 401 in the first direction F1 is W1 , and the maximum width of the first buffer groove portion 50 a in the first direction F1 is W2 , satisfying 0.3≤W2 / W1≤1.

[0176] When one side of the scoring groove 41 has a first buffer groove portion 50 a , the maximum groove width of the first buffer groove portion 50 a in the first direction F1 is W2 .

[0177] When there are multiple first buffer groove portions 50a on one side of the notched groove 41, as shown in Figure 16, the upper surface and lower surface of the first wall portion 11 respectively have a first buffer groove portion 50a, and the two first buffer groove portions 50a correspond in position and have the same groove width size. At this time, the maximum groove width W2 of the first buffer groove portion 50a in the first direction F1 is the maximum groove width of each first buffer groove portion 50a in the first direction F1; if the first buffer groove portion 50a on the upper surface and the first buffer groove portion 50a on the lower surface of the first wall portion 11 correspond in position but have different groove width sizes, the maximum groove width W2 of the first buffer groove portion 50a in the first direction F1 is the larger one of the groove width size values ​​of the two first buffer groove portions 50a in the first direction F1; as shown in Figures 17-19, when there are multiple first buffer groove portions 50a on the upper surface or lower surface of the first wall portion 11 respectively, the maximum groove width W2 of the first buffer groove portion 50a in the first direction F1 is the sum of the groove width size values ​​of the multiple first buffer groove portions 50a in the first direction F1. That is to say, when there are multiple first buffer groove portions 50a on one side of the notched groove 41, and the multiple first buffer groove portions 50a are located on the same side surface of the first wall portion 11, the sum of the groove widths of the multiple first buffer groove portions 50a is used for statistical calculation; when the upper surface and lower surface of the first wall portion 11 have the first buffer groove portion 50a at the same time, the maximum groove width of the first buffer groove portion 50a is statistically calculated based on the first buffer groove portion 50a on one side surface of the first wall portion 11.

[0178] When W2 / W1 is too small, W2 is too small, the groove width of the first buffer groove portion 50a in the front-to-back direction is small, the first wall portion 11 has high rigidity at the first buffer groove portion 50a and is not easy to deform, the buffering effect of the first buffer groove portion 50a is not obvious, and the weak area is easily pulled and damaged when the electrode assembly 20 expands; or W1 is too large, the distance between the notched groove 41 and the front and rear edges of the first wall portion 11 is too small, and the weak area is easily pulled and damaged when the electrode assembly 20 expands.

[0179] When W2 / W1 is too large, W2 is too large, the width of the first buffer groove portion 50a in the front-to-back direction is large, and the first buffer groove portion 50a occupies more space, resulting in the area of ​​the predetermined pressure relief zone 401 being too small; or W1 is too small, the area of ​​the predetermined pressure relief zone 401 is too small, which may make it difficult to meet the demand for timely discharge of the gas inside the battery cell 100, posing a safety hazard.

[0180] To this end, W2 / W1 is limited to between 0.3 and 1. W2 / W1 can be any one of 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a range between any two of them.

[0181] Therefore, by limiting W2 / W1, the area of ​​the predetermined pressure relief zone 401 can be increased to meet the exhaust requirements and improve the timeliness of the pressure relief portion explosion; at the same time, the stiffness of the first wall portion 11 at the first buffer groove portion 50a is reduced. When the electrode assembly 20 expands, the first wall portion 11 undergoes a certain deformation at the first buffer groove portion 50a, so that the expansion force can be released to a certain extent, thereby reducing the stretching of the weak area, reducing the probability of the weak area being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0182] As shown in Figure 11, in some embodiments, the maximum length of the predetermined pressure relief area 401 in the third direction F3 is L1, and the maximum groove length of the first buffer groove portion 50a in the third direction F3 is L2, satisfying: L2 / L1≥1, and the third direction F3 is perpendicular to the first direction F1 and the second direction F2 respectively.

[0183] As shown in Figure 11, the third direction F3 is the left and right direction as shown in Figure 11. In the left and right direction, if the groove length of the first buffer groove portion 50a is less than the maximum length of the predetermined pressure relief area 401, the first buffer groove portion 50a is located between a portion of the notched groove 41 and the outer edge of the first wall portion 11, and no first buffer groove portion 50 is provided between another portion of the notched groove 41 and the outer edge of the first wall portion 11, which easily causes the local notched groove 41 to be pulled and damaged. For this reason, L2 / L1 is limited to greater than or equal to 1, and L2 / L1 can be 1, 1.1, 1.15, 1.2, 1.25, etc.

[0184] As a result, the pulling force applied to each position of the entire predetermined pressure relief area 401 in the left and right directions is reduced to a certain extent. The first buffer groove portion 50a can buffer the force applied to the weak areas of each part, thereby reducing the probability of the weak areas being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0185] As shown in FIG5 , FIG6 and FIG11 , in some embodiments, the thickness of the straight area 23 in the first direction F1 is W0, and the maximum groove width of the first buffer groove portion 50a in the first direction F1 is W2, satisfying 0.1≤W2 / W0≤0.3.

[0186] When W2 / W0 is too small, W2 is too small, the groove width of the first buffer groove portion 50a in the front-to-back direction is small, the first wall portion 11 has high rigidity at the first buffer groove portion 50a and is not easy to deform, the effect of the first buffer groove portion 50a is not obvious, and the weak area is easily pulled and damaged when the electrode assembly 20 expands; or W0 is too large, the expansion amount of the electrode assembly 20 is large, and the pulling force on the notched groove 41 is greater, and the weak area is easily pulled and damaged when the electrode assembly 20 expands.

[0187] When W2 / W0 is too large, W2 is too large, the width of the first buffer groove portion 50a in the front-to-back direction is large, and the first buffer groove portion 50a occupies more space, resulting in the area of ​​the predetermined pressure relief zone 401 being too small, which may be difficult to meet the demand for timely discharge of the gas inside the battery cell 100, posing a safety hazard; or W0 is too small, the thickness of the electrode assembly 20 is small, and the energy density of the battery cell 100 is low.

[0188] To this end, W2 / W0 is limited to between 0.1-0.3, and W2 / W0 can be any one of 0.1, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3 or a range between any two of them.

[0189] Therefore, by limiting W2 / W0, the area of ​​the predetermined pressure relief zone 401 can be increased on the basis of ensuring that the battery cell 100 has a certain energy density, so as to meet the exhaust requirements and improve the timeliness of the pressure relief part explosion; at the same time, the stiffness of the first wall portion 11 at the first buffer groove portion 50a is reduced. When the electrode assembly 20 expands, the first wall portion 11 undergoes a certain deformation at the first buffer groove portion 50a, so that the expansion force can be released to a certain extent, thereby reducing the stretching of the weak area, reducing the probability of the weak area being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0190] As shown in FIG. 20 , in some embodiments, the buffer groove 50 includes a second buffer groove portion 50 b , which is located on one side of the notched groove 41 in the third direction F3 , and the third direction F3 is perpendicular to the first direction F1 and the second direction F2 .

[0191] As shown in Figures 20, 23 and 24, a second buffer groove portion 50b is respectively provided on the left and right sides of the scored groove 41, and the second buffer groove portion 50b extends in the front-to-back direction. At this time, the predetermined pressure relief area 401 can extend in the front-to-back direction, that is, the length direction of the predetermined pressure relief area 401 is the front-to-back direction, so that in the left-right direction, the second buffer groove portion 50b can correspond to the predetermined pressure relief area 401. Of course, the predetermined pressure relief area 401 can extend in the left-right direction, that is, the length direction of the predetermined pressure relief area 401 is the left-right direction. When the electrode assembly 20 expands, the first wall portion 11 is subjected to a certain pulling force in the left-right direction. By providing the second buffer groove portion 50b, the pulling force can be released to a certain extent at the second buffer groove portion 50b, thereby reducing the pulling force transmitted to the scored groove 41, reducing the probability of the scored groove 41 being pulled and damaged, reducing the risk of leakage, and improving the service life and reliability of the battery cell 100.

[0192] As shown in Figure 20, a first buffer groove portion 50a is respectively provided on the front and rear sides of the notched groove 41, and the front and rear ends of the second buffer groove portion 50b are respectively connected to the first buffer groove portion 50a, thereby making the buffer groove 50 form a ring, that is, an annular buffer groove 50 is provided on the outer circle of the notched groove 41 as a whole; of course, the front and rear ends of the second buffer groove portion 50b may also have a certain distance from the first buffer groove portion 50a.

[0193] When the electrode assembly 20 expands, the first wall portion 11 is subjected to a certain pulling force in the front-to-back direction and the left-to-right direction. By providing the first buffer groove portion 50a and the second buffer groove portion 50b, the pulling force can be released to a certain extent at the first buffer groove portion 50a and the second buffer groove portion 50b, thereby reducing the pulling force transmitted to the notched groove 41, reducing the probability of the notched groove 41 being pulled and damaged, reducing the risk of leakage, and improving the service life and reliability of the battery cell 100.

[0194] Referring to Figures 21 to 26, Figure 21 is a disassembled view of a battery cell provided in some embodiments of the present application; Figure 22 is an overhead view of the structure shown in Figure 21; Figure 23 is a disassembled view of a battery cell provided in some embodiments of the present application; Figure 24 is an overhead view of the structure shown in Figure 23; 25 is a cross-sectional view of the battery cell shown in Figure 23; Figure 26 is an enlarged view of circle G in Figure 25; in some embodiments, the housing 10 includes a pressure relief portion 40, a notched groove 41 is provided in the pressure relief portion 40, the pressure relief portion 40 and the first wall portion 11 are separately provided, the pressure relief portion 40 is installed on the first wall portion 11, and the buffer groove 50 is located in the first wall portion 11.

[0195] As shown in Figures 21 and 23, the pressure relief portion 40 is a separate structural member. The pressure relief portion 40 is provided with a notched groove 41. The pressure relief portion 40 is fixedly connected to the first wall portion 11, for example, by welding. When the electrode assembly 20 expands, the expansion force of the electrode assembly 20 pulls the first wall portion 11, and the connection between the pressure relief portion 40 and the first wall portion 11 will be pulled, causing the connection to be easily damaged. By providing a buffer groove 50 on the first wall portion 11, the first wall portion 11 can have more stretching at the buffer groove 50, thereby reducing the stretching of the connection between the pressure relief portion 40 and the first wall portion 11. The buffer groove 50 can effectively buffer the connection between the pressure relief portion 40 and the first wall portion 11, reducing the probability of the connection being pulled and damaged, resulting in leakage, and at the same time reducing the stretching at the notched groove 41, reducing the probability of the shell 10 being pulled and damaged at the notched groove 41, resulting in leakage, thereby improving the service life and reliability of the battery cell 100.

[0196] As shown in Figures 21 to 26, in some embodiments, the pressure relief portion 40 has a length direction, the maximum dimension of the pressure relief portion 40 in the length direction is L0, at least a portion of the buffer groove 50 extends along the length direction, and the maximum groove length of the buffer groove 50 in the length direction is L2, -30mm≤L2-L0≤30mm.

[0197] As shown in Figures 21 and 22, the pressure relief portion 40 extends in the left-right direction, and the buffer groove 50 includes a first buffer groove portion 50a, which extends in the left-right direction. The maximum groove length of the first buffer groove portion 50a in the left-right direction is L2. When the first buffer groove portion 50a includes multiple first buffer groove portions 50a, the maximum groove length of the multiple first buffer groove portions 50a in the left-right direction is L2.

[0198] As shown in Figures 23 and 24, the pressure relief portion 40 extends in the front-to-back direction, and the buffer groove 50 includes a second buffer groove portion 50b, which extends in the left-right direction. The maximum groove length of the second buffer groove portion 50b in the left-right direction is L2. When the second buffer groove portion 50b includes multiple second buffer groove portions 50b, the maximum groove length of the multiple second buffer groove portions 50b in the left-right direction is L2.

[0199] In the left and right directions, if L2-L0 is too small and L2 is too small, the buffering effect of the first buffer groove portion 50a on the connection between the pressure relief portion 40 and the first wall portion 11 will be too small; if L2-L0 is too small and L2 is too large, the first buffer groove portion 50a will occupy too much space, which will reduce the structural strength of the first wall portion 11. The first wall portion 11 is prone to rupture in scenarios such as falling, affecting the reliability of the battery cell 100.

[0200] To this end, L2-L0 is limited to between -30mm and 30mm. L2-L0 can be any point value among -30mm, -25mm, -20mm, -15mm, -10mm, -5mm, 0, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, or a range value between any two of them.

[0201] In this way, the buffer groove 50 can play an effective buffering role on the connection between the pressure relief part 40 and the first wall part 11, reducing the probability of the connection being pulled and damaged, resulting in leakage, and at the same time avoiding the transitional reduction in the structural strength of the first wall part 11 to a certain extent, reducing the probability of the first wall part 11 rupture during testing or use.

[0202] As shown in FIG. 26 , in some embodiments, the minimum distance between the edge of the buffer groove 50 close to the pressure relief portion 40 and the edge of the pressure relief portion 40 is W, satisfying: 0.2 mm ≤ W ≤ 25 mm.

[0203] As shown in Figure 26, in some examples, the buffer groove 50 includes a second buffer groove portion 50b, which is located on the left and right sides of the pressure relief portion 40. In the left and right directions, the minimum distance between the second buffer groove portion 50b and the edge of the pressure relief portion 40 is W; when the second buffer groove portion 50b is included, the minimum distance between the second buffer groove portion 50b closest to the pressure relief portion 40 among the multiple second buffer groove portions 50b and the edge of the pressure relief portion 40 is W.

[0204] As shown in Figure 22, in other examples, the buffer groove 50 includes a first buffer groove portion 50a, which is located on the front and rear sides of the pressure relief portion 40. In the front and rear direction, the minimum distance between the first buffer groove portion 50a and the edge of the pressure relief portion 40 is W; when the first buffer groove portion 50a is included, the minimum distance between the first buffer groove portion 50a closest to the pressure relief portion 40 among the multiple first buffer groove portions 50a and the edge of the pressure relief portion 40 is W.

[0205] Among them, if W is too small, the distance between the buffer groove 50 and the edge of the pressure relief part 40 is relatively close, which may easily cause the structural strength of the connection between the first wall part 11 and the pressure relief part 40 to be low, and thus it is easy to break in scenarios such as falling, and it is also easy to be pulled and broken under the action of the expansion force of the electrode assembly 20, affecting the reliability of the battery cell 100; if W is too large, the distance between the buffer groove 50 and the edge of the pressure relief part 40 is relatively far, and the buffering effect of the buffer groove 50 on the connection between the pressure relief part 40 and the first wall part 11 is too small.

[0206] Therefore, W is limited to between 0.2mm-25mm, and W can be any point value among 0.2mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, or a range value between any two of them.

[0207] By limiting W to the above range, the buffer groove 50 can play a certain buffering role on the connection between the pressure relief portion 40 and the first wall portion 11, thereby reducing the probability of the connection being pulled and damaged, resulting in leakage.

[0208] As shown in Figures 28 to 35, Figure 28 is a partial schematic diagram of the shell provided in some embodiments of the present application; Figure 29 is a top view of the shell provided in some embodiments of the present application; Figure 30 is a cross-sectional view along the HH line in Figure 29 provided in some embodiments; Figure 31 is a cross-sectional view along the II line in Figure 29 provided in some embodiments; Figure 32 is an enlarged view of circle J in Figure 31; Figure 33 is a cross-sectional view along the HH line in Figure 29 provided in other embodiments; Figure 34 is a cross-sectional view along the II line in Figure 29 provided in other embodiments; Figure 35 is an enlarged view of circle K in Figure 34; in some embodiments, the notch groove 41 and the buffer groove 50 are located on different side walls of the shell 10.

[0209] As shown in Figures 28 to 35, the shell 10 has a first wall portion 11 and a second wall portion 12. The first wall portion 11 has a notch groove 41, and the second wall portion 12 has a buffer groove 50. When the electrode assembly 20 expands, the expansion force acts on the second wall portion 12 and the first wall portion 11. Since the second wall portion 12 is provided with the buffer groove 50, the expansion stress is easily concentrated at the buffer groove 50 of the second wall portion 12, causing the second wall portion 12 to deform at the buffer groove 50. When the expansion force is constant, the pulling force on the first wall portion 11 can be reduced, thereby reducing the probability of the first wall portion 11 being pulled and damaged at the notch groove 41, resulting in leakage, thereby improving the service life and reliability of the battery cell 100.

[0210] By arranging the notched groove 41 and the buffer groove 50 on different side walls of the shell 10, the strength reduction of the wall portion with the notched groove 41 can be avoided to a certain extent. At the same time, the buffer groove 50 is arranged on the other wall portion to release part of the expansion stress, which can achieve buffering of the force applied to the notched groove 41, which is beneficial to reduce the probability of the notched groove 41 being pulled and damaged, resulting in leakage, and improve the service life and reliability of the battery cell 100.

[0211] In some embodiments, the electrode assembly 20 includes at least one positive electrode sheet 21 and at least one negative electrode sheet 22. The at least one positive electrode sheet 21 and the at least one negative electrode sheet 22 are stacked to form a straight area 23. At least a portion of the positive electrode sheet 21 and at least a portion of the negative electrode sheet 22 are stacked in the straight area 23 along a first direction F1.

[0212] The outer shell 10 includes a first wall portion 11 and two second wall portions 12 connected to the first wall portion 11. The two second wall portions 12 are respectively located on both sides of the electrode assembly 20 along the first direction F1. The first wall portion 11 is located on one side of the electrode assembly 20 in the second direction F2. The second direction F2 is the thickness direction of the first wall portion 11 and is perpendicular to the first direction F1. The first wall portion 11 is provided with a notch groove 41, and the second wall portion 12 is provided with a buffer groove 50.

[0213] As shown in Figure 28, the shell 10 includes a first wall portion 11 and two second wall portions 12. The two second wall portions 12 are respectively located on both sides of the electrode assembly 20 in the first direction F1. Most of the expansion of the electrode assembly 20 will act on the second wall portion 12. The first wall portion 11 is located on one side of the electrode assembly 20 in the second direction F2. The second direction F2 is perpendicular to the first direction F1. The thickness direction of the first wall portion 11 is the second direction F2. A notched groove 41 is provided on the first wall portion 11, wherein the notched groove 41 can be integrally formed on the first wall portion 11, and the first wall portion 11 forms a weak area at the notched groove 41, or the notched groove 41 can be formed on the pressure relief portion 40, and the pressure relief portion 40 is installed on the first wall portion 11, and the pressure relief portion 40 forms a weak area at the notched groove 41.

[0214] When the electrode assembly 20 expands, the first wall portion 11 is affected less by the electrode assembly 20 than the second wall portion 12. Since the pressure relief portion 40 is located on the first wall portion 11, the risk of the expansion of the electrode assembly 20 blocking or damaging the pressure relief portion 40 can be reduced.

[0215] The second wall portion 12 is provided with a buffer groove 50. When the electrode assembly 20 expands, the expansion force acts on the second wall portion 12 and the first wall portion 11, and the expansion stress is easily concentrated at the buffer groove 50 of the second wall portion 12, causing the second wall portion 12 to deform at the buffer groove 50. When the expansion force is constant, the pulling force on the first wall portion 11 can be reduced, thereby reducing the probability of the first wall portion 11 being pulled and damaged at the notched groove 41, resulting in leakage, thereby improving the service life and reliability of the battery cell 100.

[0216] As shown in Figures 30-35, in some embodiments, the buffer groove 50 is located at one end of the second wall portion 12 close to the first wall portion 11, and the buffer groove 50 has an edge close to the first wall portion 11. The minimum distance between the edge and the inner wall surface of the first wall portion 11 is M, satisfying: 0≤M≤5mm, preferably, 0≤M≤2mm.

[0217] As shown in Figure 35, the second wall portion 12 is located above the first wall portion 11, the lower end of the second wall portion 12 is connected to the first wall portion 11, the buffer groove 50 is located at the lower end of the second wall portion 12, and the buffer groove 50 has a lower edge close to the first wall portion 11, and the minimum distance between the lower edge and the inner wall surface of the first wall portion 11 is M.

[0218] Among them, if M is too large, that is, the distance between the lower edge of the buffer groove 50 and the inner wall surface of the first wall portion 11 is too large, the buffering effect of the buffer groove 50 on the notch groove 41 is too small, and the buffering effect is not obvious. For this reason, M can be limited to between 0-5mm, and M can be any point value of 0, 1mm, 2mm, 3mm, 4mm, 5mm, or a range value between any two of them.

[0219] Therefore, the buffer groove 50 can play a certain buffering role on the weak area, reducing the probability of the weak area being pulled and damaged, resulting in leakage.

[0220] In some examples, 0≤M≤2mm, that is, M can be any point value of 0, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or a range value between any two of them.

[0221] Therefore, the buffer groove 50 can further play a certain buffering role on the weak area, reducing the probability of the weak area being pulled and damaged, resulting in leakage.

[0222] As shown in FIG. 32 and FIG. 35 , in some embodiments, the maximum groove width of the buffer groove 50 in the second direction F2 is N, satisfying 3 mm ≤ N ≤ 6 mm.

[0223] As shown in Figures 32 and 35 , when a second wall portion 12 has one buffer groove 50, the maximum groove width of the buffer groove 50 in the second direction F2 is N. When a second wall portion 12 has multiple buffer grooves 50, and the multiple buffer grooves 50 are located on the same side surface of the second wall portion 12, the sum of the groove widths of the multiple buffer grooves 50 is the maximum groove width N. When the second wall portion 12 has buffer grooves 50 on both the inner and outer surfaces, the maximum groove width of the buffer groove 50 is the larger of the maximum groove widths of the buffer grooves 50 on each side surface of the second wall portion 12.

[0224] When the maximum groove width N of the buffer groove 50 is too small, the second wall portion 12 has high rigidity at the buffer groove 50 and is not easy to deform, the buffering effect of the buffer groove 50 is not obvious, and the weak area is easily pulled and damaged when the electrode assembly 20 expands; when the maximum groove width N of the buffer groove 50 is too large, the strength of the second wall portion 12 at the buffer groove 50 is too small, and the second wall portion 12 is easily broken in scenarios such as falling, affecting the reliability of the battery cell 100.

[0225] Thus, the maximum groove width N of the buffer groove 50 is limited between 3mm and 6mm, and N can be any point value of 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, or 6mm, or a range value between any two of them.

[0226] By limiting the maximum groove width N of the buffer groove 50 within the above-mentioned range, the buffer groove 50 can play an effective buffering role on the notched groove 41, reducing the probability of the connection being pulled and damaged, resulting in leakage, and at the same time avoiding the transitional reduction in the structural strength of the second wall portion 12 to a certain extent, reducing the probability of the second wall portion 12 rupturing during testing or use.

[0227] As shown in Figures 30-32, in some embodiments, the buffer groove 50 is located at one end of the second wall portion 12 close to the first wall portion 11, and the buffer groove 50 has an edge close to the first wall portion 11. The minimum distance between the edge and the inner wall surface of the first wall portion 11 is M, and the maximum groove width of the buffer groove 50 in the second direction F2 is N, satisfying: M=0, and 5mm≤N≤6mm.

[0228] As shown in Figures 31 and 32, the second wall portion 12 is located above the first wall portion 11, and the lower end of the second wall portion 12 is connected to the first wall portion 11. The buffer groove 50 is located at the lower end of the second wall portion 12, and the buffer groove 50 has a lower edge close to the first wall portion 11. The minimum distance M between the lower edge and the inner wall surface of the first wall portion 11 is 0, that is, the lower edge of the buffer groove 50 extends to the first wall portion 11, so that when the electrode assembly 20 expands, a stress concentration point is formed at the lower end of the second wall portion 12, reducing the probability of the expansion force being concentrated at the position of the notched groove 41, thereby reducing the probability of the notched groove 41 being pulled and damaged, resulting in leakage, and improving the reliability of the battery cell 100.

[0229] Among them, 5mm≤N≤6mm, N can be any point value of 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, 6mm, or a range value between any two of them.

[0230] In this way, the buffer groove 50 can play an effective buffering role on the notched groove 41, reducing the probability of the notched groove 41 being pulled and damaged, resulting in leakage, and at the same time avoiding the transitional reduction in the structural strength of the second wall portion 12 to a certain extent, reducing the probability of the second wall portion 12 breaking during testing or use.

[0231] In some examples, the second wall portion 12 can form a flat plate structure, in which case the thickness of the second wall portion 12 at different positions is the same; or, the second wall portion 12 can include a main body area and a local area, and the local area can be provided with a groove, a protrusion, or other special structures such as a hole. For example, the local area has an arc structure that is convenient for connection with other wall portions. The local area can be located around the main body area, or in the middle of the main body area, or can be arranged in a dispersed manner. At this time, the thickness dimension of the second wall portion 12 is the thickness dimension of the main body area, and the thickness dimension of the second wall portion 12 is H0, wherein 0.4mm≤H0≤2.0mm, preferably, 0.4mm≤H0≤1.0mm, and the minimum thickness of the second wall portion 12 at the buffer groove 50 is H2, 0.5≤H2 / H0≤0.7.

[0232] In addition, the upper part of the buffer groove 50 has a transition zone 51, and the thickness of the transition zone 51 gradually increases from bottom to top, thereby making the upper edge of the buffer groove 50 and the main area of ​​the second wall portion 12 smoothly transition. In the up and down directions, the width of the transition zone 51 is O, 3mm≤O ≤5mm, thereby avoiding the sudden decrease in the thickness of the second wall portion 12 at the buffer groove 50, and to a certain extent avoiding the damage of the second wall portion 12 at the buffer groove 50, thereby improving the reliability of the battery cell 100.

[0233] As shown in Figures 33-35, in some embodiments, the buffer groove 50 is located at one end of the second wall portion 12 close to the first wall portion 11, and the buffer groove 50 has an edge close to the first wall portion 11. The minimum distance between the edge and the inner wall surface of the first wall portion 11 is M, and the maximum groove width of the buffer groove 50 in the second direction F2 is N, satisfying: 0<M≤2mm, and 3mm≤N≤4mm.

[0234] As shown in Figures 34 and 35, the second wall portion 12 is located above the first wall portion 11, and the lower end of the second wall portion 12 is connected to the first wall portion 11. The buffer groove 50 is located at the lower end of the second wall portion 12, and the buffer groove 50 has a lower edge close to the first wall portion 11. The lower edge is spaced apart from the inner wall surface of the first wall portion 11, and the minimum distance M between the lower edge and the inner wall surface of the first wall portion 11 is not greater than 2 mm. M can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, and 2 mm, or a range value between any two of them.

[0235] Among them, 3mm≤N≤4mm, N can be any point value of 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, or a range value between any two of them.

[0236] As a result, the buffer groove 50 can effectively buffer the notched groove 41, reducing the probability of the notched groove 41 being pulled and damaged, resulting in leakage, while at the same time avoiding the transitional reduction in the structural strength of the second wall portion 12 to a certain extent, and reducing the probability of the second wall portion 12 rupturing during testing or use.

[0237] As shown in Figures 30 and 33, in some embodiments, the buffer groove 50 extends along the third direction F3. In the third direction F3, the buffer groove 50 is spaced apart from the edge of the second wall portion 12. The third direction F3 is perpendicular to the first direction F1 and the second direction F2.

[0238] As shown in Figures 30 and 33, the buffer groove 50 is arranged on the inner surface of the second wall portion 12, and the buffer groove 50 extends in the left and right directions. The left and right edges of the buffer groove 50 are respectively spaced apart from the left and right edges of the second wall portion 12. This can, to a certain extent, avoid the end of the buffer groove 50 from extending to the adjacent wall portion, affecting the strength of the connection between the second wall portion 12 and the adjacent wall portion, so that the buffer groove 50 not only plays a buffering role on the notched groove 41, but also improves the structural strength of the entire shell 10, thereby avoiding the probability of the shell 10 breaking during testing or use.

[0239] In some embodiments, a maximum length of the buffer tank 50 in the third direction F3 is smaller than a maximum length of the electrode assembly 20 in the third direction F3.

[0240] If the maximum length of the buffer slot 50 in the left-right direction is too large, the buffer slot 50 will occupy too much of the second wall portion 12, reducing the structural strength of the second wall portion 12. The second wall portion 12 may easily crack in scenarios such as drops, affecting the reliability of the battery cell 100. Therefore, the maximum length of the buffer slot 50 in the third direction F3 is limited to within the maximum length of the electrode assembly 20 in the third direction F3. This allows the buffer slot 50 to provide a buffering effect at the scored groove 41 while also improving the structural strength of the second wall portion 12, thereby preventing the second wall portion 12 from cracking during testing or use.

[0241] As shown in FIG. 11 to FIG. 38 , in some embodiments, the housing 10 includes a plurality of wall portions and a pressure relief portion 40 . The pressure relief portion 40 has a scoring groove 41 , and at least one wall portion has a buffer groove 50 .

[0242] The pressure relief portion 40 has a notched groove 41 , where a weak area is formed. The pressure relief portion 40 can be mounted on the wall of the housing 10 or can be integrally formed with the wall of the housing 10 . Buffer grooves 50 are provided on both sides of the pressure relief portion 40 along the first direction F1 .

[0243] As shown in Figures 11 to 35, the buffer groove 50 is located on a wall of the shell 10. As shown in Figures 36 to 38, Figure 36 is a schematic diagram of the shell provided in some embodiments of the present application; Figure 37 is a sectional view of the shell shown in Figure 36; Figure 38 is an enlarged view of the circle L in Figure 37, wherein buffer grooves 50 are respectively provided on the two walls of the shell. As shown in Figure 38, the buffer groove 50 is provided at the connection between the first wall 11 and the second wall 12. Therefore, when the electrode assembly 20 expands, the deformation of the shell 10 is jointly borne by the pressure relief portion 40 and multiple walls of the shell 10. The first wall 11 and the second wall 12 can undergo a certain deformation at the buffer groove 50, thereby reducing the deformation of the pressure relief portion 40, thereby reducing the risk of cracking at the pressure relief portion 40 and improving the reliability of the battery cell 100.

[0244] As shown in FIG. 11 to FIG. 20 , in some embodiments, the buffer groove 50 is provided on the inner surface and / or the outer surface of the wall.

[0245] As shown in Figures 11 and 15, one side of the notched groove 41 has a buffer groove 50, and the buffer groove 50 is arranged on the outer surface of the wall. Of course, as shown in Figure 13, the buffer groove 50 is also arranged on the inner surface of the wall; as shown in Figures 16 and 19, one side of the notched groove 41 has multiple buffer grooves 50, wherein a part of the buffer grooves 50 are arranged on the outer surface of the wall, and another part of the buffer grooves 50 are arranged on the inner surface of the wall; multiple buffer grooves 50 can also be arranged at intervals on the outer surface of the wall, and multiple buffer grooves 50 can also be arranged at intervals on the inner surface of the wall.

[0246] Therefore, a groove can be made on a single side of the wall of the shell 10 to simplify the manufacturing process; grooves can also be made on both sides of the wall of the shell 20, which can avoid the excessive reduction of the strength of the wall of the shell 20 to a certain extent, and at the same time improve the buffering effect of the buffer groove 10 on the scored groove 41, reduce the probability of the pressure relief part 40 being pulled and damaged at the rough part 41, resulting in leakage, and improve the service life and reliability of the battery cell 100.

[0247] As shown in Figure 15, in some embodiments, the maximum depth of the buffer groove 50 is H1, and the thickness of the wall of the shell 10 provided with the notched groove 41 is H0, satisfying: 25%≤H1 / H0≤97.5%; further, 40%≤H1 / H0≤80%; preferably, 50%≤H1 / H0≤70%.

[0248] As shown in Figure 15, the buffer groove 50 is set on the first wall portion 11. If H1 / H0 is too large, the maximum depth H1 of the buffer groove 50 is too large, and the thickness of the first wall portion 11 at the buffer groove 50 is too small, resulting in a transitional decrease in the strength of the first wall portion 11; or H0 is too small, the thickness of the first wall portion 11 is too small, and the first wall portion 11 is easily pulled and deformed.

[0249] If H1 / H0 is too small, the maximum depth H1 of the buffer groove 50 is too small, or the thickness of the first wall portion 11 is too large, the first wall portion 11 has high rigidity at the buffer groove 50 and is not easy to deform, the buffering effect of the buffer groove 50 is not obvious, and the weak area is easily pulled and damaged when the electrode assembly 20 expands.

[0250] Therefore, H1 / H0 is limited to 25%≤H1 / H0≤97.5%, and H1 / H0 can be any point value among 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 97.5% or a range value between any two of them.

[0251] By limiting H1 / H0, when the electrode assembly 20 expands, the wall of the shell 10 can be deformed to a certain extent at the buffer groove 50, so that the expansion force can be released to a certain extent, thereby reducing the stretching of the notched groove 41 of the pressure relief part 40, reducing the probability of the weak area being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0252] In some examples, 40%≤H1 / H0≤80%, and H1 / H0 can be any point value of 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or a range value between any two of them.

[0253] Therefore, when the electrode assembly 20 expands, the wall of the shell 10 can undergo a certain deformation at the buffer groove 50, so that the expansion force can be released to a certain extent, thereby reducing the stretching on the notched groove 41 of the pressure relief part 40, reducing the probability of the weak area being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0254] In some examples, 50%≤H1 / H0≤70%, and H1 / H0 can be any point value among 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70% or any range value between any two of them.

[0255] Therefore, when the electrode assembly 20 expands, the wall of the shell 10 can undergo a certain deformation at the buffer groove 50, so that the expansion force can be released to a certain extent, thereby reducing the stretching on the notched groove 41 of the pressure relief part 40, reducing the probability of the weak area being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0256] As shown in FIG. 15 , in some embodiments, the thickness of the wall portion of the housing 10 where the notch groove 41 is provided is H0, satisfying the following relationship: 0.4 mm ≤ H0 ≤ 2 mm.

[0257] As shown in Figure 15, if H0 is too small, the thickness of the first wall portion 11 is too small, and the first wall portion 11 is easily pulled and deformed; if H0 is too large, the thickness of the first wall portion 11 is too large, the first wall portion 11 has high rigidity at the buffer groove 50 and is not easy to deform, the buffering effect of the buffer groove 50 is not obvious, and the weak area at the notched groove is easily pulled and damaged when the electrode assembly 20 expands.

[0258] Therefore, H0 is limited between 0.4mm-2mm. H0 can be any point value among 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or a range value between any two of them.

[0259] In the above technical solution, the buffer groove 50 can play an effective buffering role on the notched groove 41, reducing the probability of the notched groove 41 being pulled and damaged, resulting in leakage, and at the same time avoiding the excessive reduction of the structural strength of the shell 10 to a certain extent, reducing the probability of the shell 10 breaking during testing or use.

[0260] As shown in Figure 13, a wall portion of the shell 10 is provided with a buffer groove 50, and the thickness of the wall portion is H0, 0.4mm≤H0≤2mm. The thickness of the other wall portion not provided with the buffer groove 50 may be the same as the thickness of the wall portion or different. As shown in Figure 38, both walls of the shell 10 are provided with buffer grooves 50. At this time, the thickness of one wall portion is H0, which satisfies 0.4mm≤H0≤2mm, and the thickness of the other wall portion is H0, and satisfies 0.4mm≤H0≤2mm. The thickness of the two walls may be the same or different.

[0261] As shown in FIG. 13 , in some embodiments, the minimum thickness of the housing 10 at the buffer groove 50 is H2, satisfying: 0.05 mm ≤ H2 ≤ 1.5 mm.

[0262] If H2 is too large, the rigidity of the outer shell 10 at the buffer groove 50 is too large, the outer shell 10 is not easy to deform at the buffer groove 50, the buffering effect of the buffer groove 50 is not obvious, and the weak area at the notched groove 41 is easily pulled and damaged when the electrode assembly 20 expands; if H2 is too small, the strength of the outer shell 10 at the buffer groove 50 is too small, and the outer shell 10 is easy to break in scenarios such as falling, affecting the reliability of the battery cell 100.

[0263] Therefore, H2 is limited to between 0.05mm and 1.5mm. H2 can be any point value among 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, or a range value between any two of them.

[0264] By limiting H2, the outer shell 10 has appropriate strength at the buffer groove 50, which can not only prevent the outer shell 10 from breaking in scenarios such as falling, but also cause a certain deformation when the electrode assembly 20 expands, thereby buffering the force at the score groove 41, reducing the probability of the weak area at the score groove 41 being pulled and damaged, resulting in leakage, and improving the service life and reliability of the battery cell 100.

[0265] As shown in FIG. 32 , in some embodiments, a transition zone 51 is provided on the periphery of the buffer groove 50 , and the thickness of the transition zone 51 gradually increases in a direction away from the center of the buffer groove 50 .

[0266] As shown in Figure 32, a buffer groove 50 is provided at the lower end of the second wall portion 12, and a transition zone 51 is provided at the upper portion of the buffer groove 50. The thickness of the transition zone 51 gradually increases from bottom to top, thereby making the upper edge of the buffer groove 50 and the main area of ​​the second wall portion 12 smoothly transition. This can avoid the thickness of the outer shell 10 from suddenly decreasing at the buffer groove 50, and to a certain extent avoid the damage of the outer shell 10 at the buffer groove 50 due to stress concentration, thereby improving the reliability of the battery cell 100, and at the same time, the buffer groove 50 can be injection molded as one piece with the outer shell 10 through a mold, making the manufacturing molding process of the buffer groove 50 simpler.

[0267] As shown in FIG. 32 , in some embodiments, along a direction away from the center of the buffer groove 50 , the width dimension of the transition zone 51 is O, satisfying: 3 mm ≤ O ≤ 5 mm.

[0268] As shown in Figure 32, the transition zone 51 is located above the buffer groove 50, and the width of the transition zone 51 in the up and down directions is O. If O is too large, the transition zone 51 occupies too much space, which is easy to affect the structural strength of the wall. If O is too small, the transition zone 51 is too small, and the cross-section of the main area of ​​the buffer groove 50 and the second wall portion 12 suddenly changes, which is easy to concentrate stress. The second wall portion 12 is easy to rupture at the buffer groove 50, and the buffer groove 50 is not easy to demold during injection molding.

[0269] Therefore, O is limited to between 3mm and 5mm, and O can be any point value of 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5mm, or a range value between any two of them.

[0270] By limiting the width of the transition zone 51 , it is not only convenient to integrally inject the buffer groove 50 and the housing 10 , but also the strength of the housing 10 can be improved, the probability of the housing 10 breaking at the buffer groove 50 can be reduced, and the reliability and service life of the battery cell 100 can be improved.

[0271] As shown in Figures 39 to 41, Figure 39 is a schematic diagram of the first wall portion provided in some embodiments of the present application; Figure 40 is a cross-sectional view along the MM line in Figure 39 provided in some embodiments; Figure 41 is a cross-sectional view along the MM line in Figure 39 provided in other embodiments. In some embodiments, the housing 10 includes a pressure relief portion 40, the pressure relief portion 40 has a notched groove 41, and the pressure relief portion 40 is integrally formed with the wall portion of the housing 10.

[0272] By integrally forming the pressure relief portion 40 with the first wall portion 11 , the reliability of the pressure relief portion 40 can be improved, the connection process between the pressure relief portion 40 and the first wall portion 11 is omitted, and the manufacturing cost of the battery cell 100 can be reduced.

[0273] As shown in FIG. 40 and FIG. 41 , in some embodiments, a groove 113 is provided on the inner surface and / or outer surface of the first wall portion 11 , and a bottom wall of the groove 113 forms a pressure relief portion 40 .

[0274] As shown in FIG. 40 , the inner surface of the first wall portion 11 faces the inside of the housing 10 , and the outer surface of the first wall portion 11 faces the outside of the housing 10 . Here, the inner surface of the first wall portion 11 may be provided with a groove 113, and the outer surface of the first wall portion 11 may not be provided with the groove 113, and the portion of the first wall portion 11 located between the bottom surface of the groove 113 and the outer surface of the first wall portion 11 is the groove bottom wall of the groove 113; it is also possible that the inner surface of the first wall portion 11 is not provided with a groove 113, and the outer surface of the first wall portion 11 is provided with a groove 113, and the portion of the first wall portion 11 located between the bottom surface of the groove 113 and the inner surface of the first wall portion 11 is the groove bottom wall of the groove 113; it is also possible that both the inner and outer surfaces of the first wall portion 11 are provided with grooves 113, and the portion of the first wall portion 11 located between the bottom surfaces of the two grooves 113 is the groove bottom wall of the groove 113. It can be understood that the groove 113 provided on the inner surface of the first wall portion 11 and the groove 113 provided on the outer surface of the first wall portion 11 share a groove bottom wall.

[0275] The first wall portion 11 is thinner than the first wall portion 11 itself in the area where the groove 113 is provided, and this area forms the pressure relief portion 40 integrally formed with the first wall portion 11. Here, the groove 113 can be formed in the first wall portion 11 in various ways, such as stamping, milling, laser etching, and chemical etching.

[0276] The groove 113 can be a variety of shapes, for example, a rectangular groove, a circular groove, or an elliptical groove. A rectangular groove is a groove with a rectangular cross-section, a circular groove is a groove with a circular cross-section, and an elliptical groove is a groove with an elliptical cross-section. The cross-section referred to here is perpendicular to the depth direction of the groove 113. In this case, the pressure relief portion 40 formed on the bottom wall of the groove 113 is usually also provided with a notch groove 41. When the battery cell 100 releases pressure, the pressure relief portion 40 can split along at least a portion of the notch groove 41, thereby opening the predetermined pressure relief area 401 defined by the notch groove 41, thereby achieving rapid pressure relief.

[0277] In addition, the groove 113 can also be of other shapes. The groove 113 is a groove extending along a trajectory such as a "double Y" shape, an "I" shape, and a "W" shape. At this time, a pressure relief portion 40 is formed at the bottom of the groove 113, so that the pressure relief portion 40 forms the above-mentioned corresponding shape. The pressure relief portion 40 forms a weak area relative to the first wall portion 11. The groove 113 here can also be understood as a notched groove 41. At this time, when the battery cell 100 is depressurized, the bottom of the groove 113 cracks, the pressure relief portion 40 is destroyed, and the first wall portion 11 can form an opening at the bottom of the groove 113 to achieve pressure relief.

[0278] An integrated pressure relief portion 40 is formed by providing a groove 113 on the first wall portion 11, which is simple to implement and has low production costs. In addition, when the outer surface of the first wall portion 11 is provided with a groove 113, the groove 113 can provide an escape space for the pressure relief portion 40 to open, thereby reducing the probability that the pressure relief portion 40 cannot be opened due to being blocked by external obstacles.

[0279] As shown in FIG. 41 , in some embodiments, a groove 113 is provided on the inner surface and / or outer surface of the first wall portion 11 . The groove 113 extends circumferentially, and the area enclosed by the groove 113 forms a pressure relief portion 40 .

[0280] As shown in FIG41 , the inner surface of the first wall portion 11 faces the interior of the housing 10, and the outer surface of the first wall portion 11 faces the exterior of the housing 10. Here, the inner surface of the first wall portion 11 may be provided with the groove 113, while the outer surface of the first wall portion 11 may not be provided with the groove 113; the inner surface of the first wall portion 11 may not be provided with the groove 113, while the outer surface of the first wall portion 11 may be provided with the groove 113; or both the inner and outer surfaces of the first wall portion 11 may be provided with the groove 113, with the portion of the first wall portion 11 located between the bottom surfaces of the two grooves 113 being the bottom wall of the groove 113.

[0281] The groove 113 extends along a circumferential direction, and the groove 113 can form a closed ring. At this time, the area enclosed by the groove 113 forms a pressure relief portion 40, that is, the pressure relief portion 40 includes the groove 113 and the inner area of ​​the groove 113. The groove 113 here can also be understood as a notched groove 41. When the battery cell 100 releases pressure, the first wall portion 11 can be cracked at the groove 113, and the pressure relief portion 40 can be opened with the groove 113 as the boundary, thereby separating the pressure relief portion 40 from the first wall portion 11 to achieve rapid pressure relief.

[0282] In the above technical solution, the integrated pressure relief portion 40 is formed by providing the groove 113 on the first wall portion 11 , which is simple to implement and has low production cost.

[0283] As shown in Figures 7-10 and Figures 21-26, in some embodiments, the housing 10 includes a pressure relief portion 40, the pressure relief portion 40 has a notched groove 41, the pressure relief portion 40 is separately arranged from the wall portion of the housing 10, and the pressure relief portion 40 is installed on the wall portion of the housing 10.

[0284] As shown in Figures 7, 21 and 23, the pressure relief portion 40 and the shell 10 are two separate components, which are separately molded and then installed together. Specifically, the pressure relief portion 40 can be an explosion-proof plate, an explosion-proof valve, a safety valve and other components. The pressure relief portion 40 can be installed on the first wall portion 11 by bonding, welding and the like. The first wall portion 11 is provided with a through hole 111, and the pressure relief portion 40 is installed in the through hole 111. When the internal pressure of the battery cell 100 reaches a threshold value, the pressure relief portion 40 opens at least part of the through hole 111, and the discharge medium inside the battery cell 100 is discharged through the through hole 111 to release the pressure inside the battery cell 100.

[0285] As shown in Figure 21, taking the pressure relief portion 40 as an explosion-proof disc as an example, the explosion-proof disc is a sheet having at least a portion of its strength less than that of the first wall portion 11. The explosion-proof disc covers the through-hole and is welded to the first wall portion 11. When the internal pressure of the battery cell 100 reaches a threshold, the explosion-proof disc is at least partially destroyed, thereby opening at least a portion of the through-hole 111 to release the pressure within the battery cell 100.

[0286] In this embodiment, the pressure relief portion 40 is a component independent of the wall portion of the housing 10 . The pressure relief portion 40 and the wall portion of the housing 10 can be produced and reassembled separately, which reduces production difficulty and increases efficiency.

[0287] As shown in FIG. 7 to FIG. 38 , in some embodiments, the buffer grooves 50 are symmetrically arranged along the geometric center of the housing 10 .

[0288] As shown in Figure 11, the shell 10 has a center plane in the front-to-back direction, and the buffer grooves 50 are symmetrically arranged along the center plane, and the shell 10 has a center plane in the left-to-right direction, and the buffer grooves 50 are symmetrically arranged along the center plane. As shown in Figure 11, two buffer grooves 50 are provided on the first wall portion 11, and the two buffer grooves 50 are symmetrically arranged on the front and rear sides of the notched groove 41, and each buffer groove 50 is symmetrically arranged relative to the center of the predetermined pressure relief area 401.

[0289] Thus, the overall shell 10 forms a symmetrical structure, which, on the one hand, facilitates the manufacture of the buffer groove 50, and on the other hand, enables the buffer groove 50 to have the same buffering effect on the notched groove 41 at each position, reducing the probability of the notched groove 41 being partially pulled and broken, thereby improving the reliability of the entire battery cell 100.

[0290] In some embodiments, the buffer groove 50 is integrally formed on the housing 10 .

[0291] This can make the manufacturing process of the buffer tank 50 simpler, and simplify the manufacturing process of the battery cell 100.

[0292] The buffer groove 50 is formed by a trenching process.

[0293] By digging grooves on the outer shell 10, a buffer groove 50 is formed on the inner surface and / or outer surface of the outer shell 10. The grooves can be dug by laser etching, chemical corrosion, or machining and milling, which is convenient and facilitates precise control of the size of the buffer groove 50.

[0294] In addition, the buffer groove 50 can also be integrally formed with the shell 10 by stamping through a mold, and the buffer groove 50 can also be integrally formed with the shell 10 by 3D printing.

[0295] As shown in Figures 3, 4 and 27, in some embodiments, the housing 10 includes: a shell 101 and an end cover 102, at least one side of the shell 101 has an opening, the end cover 102 is connected to the shell 101 and is used to close the opening, and the notched groove 41 is provided on the shell 101.

[0296] The housing 101 may be a hollow structure with an opening at one end, or a hollow structure with openings at opposite ends. The housing 101 may be in various shapes, such as a prism. The housing 101 may be made of aluminum or steel.

[0297] The end cap 102 is a component that closes the opening of the shell 101 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 102 and the shell 101 together define a storage space for accommodating the electrode assembly 20, the electrolyte and other components. The shape of the end cap 102 can be adapted to the shape of the shell 10. For example, the shell 101 is a rectangular parallelepiped structure, and the end cap 102 is a rectangular plate structure adapted to the shell 10. For another example, the shell 101 is a cylindrical structure, and the end cap 102 is a circular plate structure adapted to the shell 101. The material of the end cap 102 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 102 and the shell 101 can be the same or different.

[0298] In an embodiment where the housing 101 is open at one end, one end cap 102 may be provided. In an embodiment where the housing 101 is open at two opposite ends, two end caps 102 may be provided, each of which closes the two openings of the housing 101, and the two end caps 102 and the housing 101 together define a receiving space.

[0299] The shell 101 has a first wall portion 11 and a second wall portion 12, and a notched groove 41 is provided on the shell 101. Specifically, the shell 101 has a pressure relief portion 40, and the notched groove 41 is provided on the pressure relief portion 40. The pressure relief portion 40 can be integrally formed with the shell 101, or can be separately provided with the shell 101. By providing the notched groove 41 on the shell 101, the structure of the end cover 102 can be simplified, and at the same time, it is convenient to shorten the distance between the predetermined pressure relief area 401 and the main body of the electrode assembly 20, thereby shortening the path of the discharge medium flowing to the short predetermined pressure relief area 401 during pressure relief, shortening the time for the discharge medium to reach the short predetermined pressure relief area 401, improving the timeliness of pressure relief of the battery cell 100, and thus effectively improving the reliability of the battery cell 100.

[0300] Refer to Figure 27, which is a schematic diagram of a battery cell provided in some embodiments of the present application. In some embodiments, the shell 101 has openings on both opposite sides, and the two end covers 102 are used to close the openings on the corresponding sides.

[0301] As shown in FIG27 , in an embodiment in which the housing 101 has openings formed at opposite ends, two end covers 102 may be provided. The two end covers 102 respectively close the two openings of the housing 101, and the two end covers 102 and the housing 101 together define a receiving space. The first wall portion 11 is located on the housing 101, the pressure relief portion 40 is located between the two openings, and each end cover 102 may be provided with an electrical connection portion 30. By providing two openings on the housing 101, the manufacturing and forming of the housing 101 can be facilitated, while facilitating the extraction of the tabs from the two ends of the electrode assembly 20, thereby facilitating the separation of the two electrical connection portions 30 and reducing the risk of short circuiting of the battery cell 100.

[0302] As shown in FIG. 4 and FIG. 27 , in some embodiments, the end cap 102 is provided with an electrical connection portion 30 , and the electrical connection portion 30 is electrically connected to the positive electrode sheet 21 , or the electrical connection portion 30 is electrically connected to the negative electrode sheet 22 .

[0303] The electrical connection part 30 is arranged on the end cover 102. The electrical connection part 30 can be a part of the end cover 102, and the electrical connection part 30 can also be a pole installed on the end cover 102; usually there are two electrical connection parts 30, one electrical connection part 30 is electrically connected to the pole tab of the positive electrode plate 21, and the other electrical connection part 30 is electrically connected to the pole tab of the negative electrode plate 22 to input or output the electrical energy of the battery cell 100. The electrical connection part 30 and the pole tab can be directly connected, for example, the electrical connection part 30 and the pole tab are directly welded, and the electrical connection part 30 and the pole tab can also be indirectly connected, for example, the electrical connection part 30 and the pole tab are indirectly connected through a current collecting component, and the current collecting component can be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0304] The electrical connection portion 30 and the pressure relief portion 40 are located on different sides of the housing 10, that is, the electrical connection portion 30 is located on one wall of the housing 10, and the pressure relief portion 40 is located on another wall of the housing 10. Because the electrical connection portion 30 is connected to the tab of the electrode assembly 20, a certain gap exists between the wall portion where the electrical connection portion 30 is located and the main body of the electrode assembly 20. By arranging the electrical connection portion 30 and the notched groove 41 on different walls of the housing 10, the distance between the predetermined pressure relief area 401 and the main body can be shortened. Therefore, when the battery cell 100 thermally runs away, most of the exhaust medium in the housing 10 can flow directly from the edge of the main body to the predetermined pressure relief area 401, thereby shortening the path for the exhaust medium to flow to the predetermined pressure relief area 401. This allows the exhaust medium to flow quickly to the predetermined pressure relief area 401, shortening the time it takes for the exhaust medium to reach the predetermined pressure relief area 401, and improving the timeliness of the pressure relief of the battery cell 100, thereby effectively improving the reliability of the battery cell 100.

[0305] As shown in FIG. 3 , in some embodiments, the housing 101 has a first wall portion 11 . The first wall portion 11 is provided with a notch groove 41 . The first wall portion 11 is used to support the electrode assembly 20 and is located below the electrode assembly 20 .

[0306] Therefore, the notched groove 41 can be provided at the bottom of the battery cell 100, and an exhaust channel can be provided at the bottom of the battery cell 100. The exhaust channel can be connected to the predetermined pressure relief area 401, so that when thermal runaway occurs in the battery cell 100, the high-temperature and high-pressure flue gas can be discharged into the exhaust channel through the predetermined pressure relief area 401 at the bottom, and then discharged to the outside.

[0307] Referring to Figures 42 to 44, Figure 42 is a schematic diagram of a pressure relief portion provided in some embodiments of the present application; Figure 43 is a schematic diagram of a pressure relief portion provided in other embodiments of the present application; Figure 44 is a schematic diagram of a pressure relief portion provided in still other embodiments of the present application; in some embodiments, the predetermined pressure relief area 401 has a predetermined opening boundary, and the predetermined opening boundary is surrounded by the outer edge of the positive projection of at least a portion of the scored groove 41 in the depth direction of the scored groove 41; or the predetermined opening boundary is surrounded by the connecting line between multiple ends of the scored groove 41; or the predetermined opening boundary is jointly surrounded by the connecting line between multiple ends of the scored groove 41 and the outer edge of the positive projection of at least a portion of the scored groove 41 in the depth direction of the scored groove 41.

[0308] In some embodiments, the pressure relief portion 40 is provided with a predetermined pressure relief area 401 and a notched groove 41, and the predetermined pressure relief area 401 has a predetermined opening boundary, and the predetermined opening boundary is surrounded by the outer edge of the positive projection of at least a portion of the notched groove 41 in the second direction F2; or the predetermined opening boundary is surrounded by the connecting line between multiple ends of the notched groove 41; or the predetermined opening boundary is jointly surrounded by the connecting line between multiple ends of the notched groove 41 and the outer edge of the positive projection of at least a portion of the notched groove 41 in the second direction F2.

[0309] As shown in Figure 42, in some embodiments, the scoring groove 41 includes two first arc segments 411 arranged opposite to each other and two first straight line segments 412 arranged in parallel, and the two ends of each first straight line segment 412 are respectively connected to the two first arc segments 411, and the two first straight line segments 412 and the two first arc segments 411 form a closed annular structure; in the second direction F2, the outer edge of the positive projection of the annular structure constitutes the predetermined opening boundary of the predetermined pressure relief area 401, that is, the predetermined opening boundary is surrounded by the outer edge of the positive projection of the scoring groove 40 in the second direction F2.

[0310] At this time, the maximum width of the predetermined pressure relief zone 401 along the first direction F1 is W1, W1=b, and the maximum length of the predetermined pressure relief zone 401 along the third direction F3 is L1, L1=a+b, where a represents the length of the first straight line segment 412, and b represents the distance between the outer sides of the two first straight line segments 412.

[0311] As shown in Figure 43, in some embodiments, the scoring groove 41 includes a second straight line segment 413 and four third straight line segments 414, and the two ends of the second straight line segment 413 are respectively connected to two third straight line segments 414 set at a preset angle; in the second direction F2, an arc segment 415 with the vertex of the preset angle as the center is defined between the free ends of the positive projections of the two third straight line segments 414 located at the same end of the second straight line segment 413, and a fourth straight line segment 416 is defined between the free ends of the positive projections of the two third straight line segments 414 located on the same side of the second straight line segment 413. The two arc segments 415 and the two fourth straight line segments 416 together constitute a predetermined opening boundary of the predetermined pressure relief area 401, that is, the predetermined opening boundary is surrounded by the connecting lines between the multiple ends of the scoring groove 40.

[0312] At this time, the maximum width of the predetermined pressure relief zone 401 along the first direction F1 is W1, W1 = 2d × sinα, and the maximum length of the predetermined pressure relief zone 401 along the third direction F3 is L1, L1 = c + 2d, where c represents the length of the second straight line segment 413, d represents the length of the third straight line segment 414, and e represents the length of the fourth straight line segment 416. The angle between the two third straight line segments 414 located at the same end of the second straight line segment 413 is 2α.

[0313] As shown in Figure 44, in some embodiments, the scoring groove 41 includes a fifth straight line segment 417 and two sixth straight line segments 418, the fifth straight line segment 417 is located between the two sixth straight line segments 418, and the ends of the fifth straight line segment 417 are respectively connected to the middle parts of the corresponding sixth straight line segments 418, and a seventh straight line segment 419 is defined between the ends of the two sixth straight line segments 418 located on the same side of the fifth straight line segment 417, and the outer edges of the positive projections of the seventh straight line segment 419 and the sixth straight line segment 418 in the second direction F2 constitute a predetermined opening boundary of the predetermined pressure relief area 401, that is, the predetermined opening boundary is jointly surrounded by the connecting lines between the multiple ends of the scoring groove 40 and the outer edges of the positive projections of a part of the scoring groove 40 in the second direction.

[0314] Of course, a flip notch 419 can be set at the seventh straight segment 419 of the notch groove 41, thereby correspondingly setting two flip notches 419, and the two flip notches 419 are located on both sides of the fifth straight segment 417. The setting of the flip notch 419 is conducive to the pressure relief part 40 to relieve pressure along the predetermined opening boundary, thereby ensuring the effectiveness of the pressure relief area.

[0315] At this time, the maximum width of the predetermined pressure relief area 401 along the first direction F1 is W1, W1=j, and the maximum length of the predetermined pressure relief area 401 along the third direction F3 is L1, L1=k, where j represents the length of the sixth straight line segment 418 and k represents the length of the seventh straight line segment 419.

[0316] The use of the notched groove 41 with the above structure is beneficial to the rapid pressure relief of the pressure relief portion 40 .

[0317] The battery 1000 according to the second embodiment of the present application includes the battery cell 100 according to the first embodiment of the present application.

[0318] According to an embodiment of the third aspect of the present application, an electrical device includes the battery 1000 according to the embodiment of the second aspect of the present application, and the battery 1000 is used to provide power to the electrical device. Thus, by using the battery 1000, the safety and reliability of the electrical device can be improved.

[0319] Optionally, as shown in FIG1 , when battery 1000 is used in a vehicle, it can be located at the bottom, front, or rear of the vehicle. Battery 1000 can be used to power the vehicle, for example, as an operating power source for the vehicle. The vehicle can also include a controller and a motor, with the controller controlling battery 1000 to power the motor, for example, to meet the vehicle's starting, navigation, and operating power requirements during driving.

[0320] A battery 1000 and a vehicle 2000 having the same according to a specific embodiment of the present application will be described below with reference to the accompanying drawings.

[0321] As shown in FIG. 1 , a battery 1000 is provided at the bottom of a vehicle 2000 . As shown in FIG. 2 , the battery 1000 includes a plurality of battery cells 100 . As shown in FIG. 3 and FIG. 4 , each battery cell 100 includes a housing 10 and an electrode assembly 20 .

[0322] The electrode assembly 20 is arranged in the outer shell 10, and the electrode assembly 20 includes at least one positive electrode sheet 21 and at least one negative electrode sheet 22. The at least one positive electrode sheet 21 and the at least one negative electrode sheet 22 are stacked to form a flat area 23. At least a portion of the positive electrode sheet 21 and at least a portion of the negative electrode sheet 22 are stacked in the flat area 23 along the first direction F1.

[0323] As shown in Figures 3 and 4, the shell 10 can be roughly in the shape of a quadrangular prism, with a simple structure and easy to form. The shell 10 is provided with an electrical connection part 30 and a pressure relief part 40. The shell 10 includes a shell 101 and an end cover 102. The electrical connection part 30 is arranged on the end cover 102. The shell 101 has a first wall part 11 and two oppositely arranged second wall parts 12. The pressure relief part 40 is arranged on the first wall part 11. The pressure relief part 40 has a notched groove 41. The notched groove 41 defines a predetermined pressure relief area 401 that is opened when the battery cell 100 is depressurized.

[0324] Therefore, the electrical connection part 30 and the pressure relief part 40 are located on different sides of the outer shell 10, which can shorten the distance between the pressure relief part 40 and the main part of the electrode assembly 20. Therefore, when the battery cell 100 thermally runs away, most of the discharge medium in the outer shell 10 can flow directly from the edge of the main part of the electrode assembly 20 to the pressure relief part 40, thereby shortening the path of the discharge medium flowing to the pressure relief part 40, allowing the discharge medium to flow quickly to the pressure relief part 40, shortening the time for the discharge medium to reach the pressure relief part 40, and improving the timeliness of the pressure relief of the battery cell 100, thereby effectively improving the reliability of the battery cell 100.

[0325] As shown in Figure 11, two buffer grooves 50 are provided on the first wall portion 11, and the two buffer grooves 50 are respectively located on the front and rear sides of the notched groove 41, wherein the maximum width of the predetermined pressure relief area 401 in the first direction F1 is W1, and the maximum groove width of each buffer groove 50 in the first direction F1 is W2, satisfying 0.3≤W2 / W1≤1.

[0326] The thickness of the flat region 23 in the first direction F1 is W0, which satisfies 0.1≤W2 / W0≤0.3.

[0327] The maximum length of the predetermined pressure relief area 401 in the third direction F3 is L1, and the maximum length of each buffer groove 50 in the third direction F3 is L2, satisfying: L2 / L1≥1.

[0328] As shown in FIG15 , the maximum depth of the buffer groove 50 is H1 , and the thickness of the first wall portion 11 is H0 , which satisfies: 25%≤H1 / H0≤97.5%; and the thickness H0 of the first wall portion 11 satisfies: 0.4mm≤H0≤2mm.

[0329] Therefore, by setting a buffer groove 50 on the outside of the scored groove 41, the shell 10 can undergo a certain deformation at the buffer groove 50 when the electrode assembly 20 expands, so that the expansion force of the electrode assembly 20 can be released to a certain extent at the buffer groove 50, reducing the force transmitted to the scored groove 41, thereby reducing the deformation of the shell 10 at the scored groove 41, reducing the probability of the shell 10 being pulled and damaged at the scored groove 41, and causing leakage, thereby improving the service life and reliability of the battery cell 100.

[0330] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that, comprising: an electrode assembly; a housing for accommodating the electrode assembly, the housing being provided with a scoring groove and a buffer groove, the scoring groove defining a predetermined pressure relief area that opens when the battery cell relieves pressure, and the buffer groove being located on a side of the scoring groove away from the geometric center of the predetermined pressure relief area.

2. The battery cell according to claim 1, characterized in that, the scoring groove and the buffer groove are located on the same side wall of the housing, and the buffer groove is arranged closer to the edge of the housing relative to the scoring groove.

3. The battery cell according to claim 2, characterized in that, the housing includes a pressure relief portion, the pressure relief portion is separately provided from the wall portion of the housing, the pressure relief portion has the scoring groove, the buffer groove is provided on the pressure relief portion and is located on a side of the scoring groove away from the geometric center of the predetermined pressure relief area, and the thickness of the pressure relief portion at the buffer groove is greater than the thickness of the pressure relief portion at the scoring groove.

4. The battery cell according to claim 2, characterized in that, the electrode assembly includes at least one positive electrode tab and at least one negative electrode tab, and a flat area is formed after the at least one positive electrode tab and the at least one negative electrode tab are stacked, and at least a part of the positive electrode tab and at least a part of the negative electrode tab are stacked in the flat area in a first direction. The housing includes a first wall portion, the first wall portion is located on one side of the electrode assembly in a second direction, the second direction is the thickness direction of the first wall portion and is perpendicular to the first direction, and the first wall portion is provided with the scoring groove and the buffer groove.

5. The battery cell according to claim 4, characterized in that, the buffer groove includes a first buffer groove portion, and the first buffer groove portion is located on one side of the scoring groove in the first direction.

6. The battery cell according to claim 5, characterized in that, the maximum width of the predetermined pressure relief area in the first direction is W1, and the maximum groove width of the first buffer groove portion in the first direction is W2, satisfying 0.3 ≤ W2 / W1 ≤ 1.

7. The battery cell according to claim 5, characterized in that, the maximum length of the predetermined pressure relief area in a third direction is L1, and the maximum groove length of the first buffer groove portion in the third direction is L2, satisfying: L2 / L1 ≥ 1, and the third direction is perpendicular to the first direction and the second direction respectively.

8. The battery cell according to claim 5, characterized in that, the thickness of the flat area in the first direction is W0, and the maximum groove width of the first buffer groove portion in the first direction is W2, satisfying 0.1 ≤ W2 / W0 ≤ 0.

3.

9. The battery cell according to any one of claims 4-8, characterized in that, the buffer groove includes a second buffer groove portion, and the second buffer groove portion is located on one side of the scoring groove in the third direction, and the third direction is perpendicular to the first direction and the second direction respectively.

10. The battery cell according to any one of claims 4-9, characterized in that, The outer shell includes a pressure relief portion, the scoring groove is provided in the pressure relief portion, the pressure relief portion is separately provided from the first wall portion, the pressure relief portion is installed on the first wall portion, and the buffer groove is located in the first wall portion.

11. The battery cell according to claim 10, wherein, the pressure relief portion has a length direction, the maximum dimension of the pressure relief portion in the length direction is L0, at least a part of the buffer groove extends along the length direction, and the maximum groove length of the buffer groove in the length direction is L2, -30 mm ≤ L2 - L0 ≤ 30 mm.

12. The battery cell according to claim 10, wherein, the minimum distance between the edge of the buffer groove close to the pressure relief portion and the edge of the pressure relief portion is W, satisfying: 0.2 mm ≤ W ≤ 25 mm.

13. The battery cell according to claim 1, wherein, the scoring groove and the buffer groove are located on different side walls of the outer shell.

14. The battery cell according to claim 13, wherein, the electrode assembly includes at least one positive electrode tab and at least one negative electrode tab, the at least one positive electrode tab and the at least one negative electrode tab form a flat area after being stacked, and at least a part of the positive electrode tab and at least a part of the negative electrode tab are stacked in a first direction in the flat area; the outer shell includes a first wall portion and two second wall portions connected to the first wall portion, the two second wall portions are respectively located on both sides of the electrode assembly along the first direction, the first wall portion is located on one side of the electrode assembly in a second direction, the second direction is the thickness direction of the first wall portion and is perpendicular to the first direction, the scoring groove is provided in the first wall portion, and the buffer groove is provided in the second wall portion.

15. The battery cell according to claim 14, wherein, the buffer groove is located at one end of the second wall portion close to the first wall portion, the buffer groove has an edge close to the first wall portion, and the minimum distance between the edge and the inner wall surface of the first wall portion is M, satisfying: 0 ≤ M ≤ 5 mm, preferably, 0 ≤ M ≤ 2 mm.

16. The battery cell according to claim 14, wherein, the maximum groove width of the buffer groove in the second direction is N, satisfying, 3 mm ≤ N ≤ 6 mm.

17. The battery cell according to claim 14, wherein, the buffer groove is located at one end of the second wall portion close to the first wall portion, the buffer groove has an edge close to the first wall portion, the minimum distance between the edge and the inner wall surface of the first wall portion is M, and the maximum groove width of the buffer groove in the second direction is N, satisfying: M = 0, and 5 mm ≤ N ≤ 6 mm.

18. The battery cell according to claim 14, wherein, The buffer groove is located at one end of the second wall portion close to the first wall portion. The buffer groove has an edge close to the first wall portion, and the minimum distance between the edge and the inner wall surface of the first wall portion is M. The maximum groove width of the buffer groove in the second direction is N, satisfying: 0 < M ≤ 2 mm, and 3 mm ≤ N ≤ 4 mm.

19. The battery cell according to claim 14, wherein, the buffer groove extends in a third direction. In the third direction, the buffer groove and the edge of the second wall portion are arranged at intervals, and the third direction is perpendicular to the first direction and the second direction respectively.

20. The battery cell according to claim 19, wherein, the maximum length of the buffer groove in the third direction is less than the maximum length of the electrode assembly in the third direction.

21. The battery cell according to any one of claims 1, 4 - 20, wherein, the outer shell includes a plurality of wall portions and a pressure relief portion. The pressure relief portion has the notch groove, and at least one of the wall portions has the buffer groove.

22. The battery cell according to claim 21, wherein, the buffer groove is provided on the inner surface and / or the outer surface of the wall portion.

23. The battery cell according to claim 21, wherein, the maximum depth of the buffer groove is H1, and the thickness of the wall portion of the outer shell provided with the notch groove is H0, satisfying: 25% ≤ H1 / H0 ≤ 97.5%; further, 40% ≤ H1 / H0 ≤ 80%; preferably, 50% ≤ H1 / H0 ≤ 70%.

24. The battery cell according to claim 21, wherein, the thickness of the wall portion of the outer shell provided with the notch groove is H0, satisfying: 0.4 mm ≤ H0 ≤ 2 mm.

25. The battery cell according to claim 21, wherein, the minimum thickness of the outer shell at the buffer groove is H2, satisfying: 0.05 mm ≤ H2 ≤ 1.5 mm.

26. The battery cell according to claim 21, wherein, a transition region is provided on the outer periphery of the buffer groove, and the thickness of the transition region gradually increases in a direction away from the center of the buffer groove.

27. The battery cell according to claim 26, wherein, in a direction away from the center of the buffer groove, the width dimension of the transition region is O, satisfying: 3 mm ≤ O ≤ 5 mm.

28. The battery cell according to any one of claims 1 - 2, 4 - 9, 13 - 27, wherein, the outer shell includes a pressure relief portion. The pressure relief portion has the notch groove, and the pressure relief portion is integrally formed with the wall portion of the outer shell.

29. The battery cell according to any one of claims 1 - 27, wherein, the outer shell includes a pressure relief portion. The pressure relief portion has the notch groove, the pressure relief portion is separately provided from the wall portion of the outer shell, and the pressure relief portion is installed on the wall portion of the outer shell.

30. The battery cell according to any one of claims 1 - 29, wherein, the buffer grooves are symmetrically arranged along the geometric center of the outer shell.

31. The battery cell according to any one of claims 1-30, characterized in that, the buffer groove is integrally formed on the outer shell.

32. The battery cell according to claim 31, characterized in that, the buffer groove is formed by a grooving process.

33. The battery cell according to any one of claims 1-32, characterized in that, the outer shell includes: a housing and an end cap, at least one side of the housing has an opening, the end cap is connected to the housing and is used to close the opening, and the scoring groove is provided on the housing.

34. The battery cell according to claim 33, characterized in that, both opposite sides of the housing have openings, and the two end caps are used to close the openings on the corresponding sides.

35. The battery cell according to claim 33 or 34, characterized in that, the end cap is provided with an electrical connection part, the electrical connection part is electrically connected to the positive electrode tab of the electrode assembly, or the electrical connection part is electrically connected to the negative electrode tab of the electrode assembly.

36. The battery cell according to any one of claims 33-35, characterized in that, the housing has a first wall portion, the scoring groove is provided on the first wall portion, and the first wall portion is used to support the electrode assembly and is located below the electrode assembly.

37. The battery cell according to any one of claims 1-36, characterized in that, the predetermined pressure relief area has a predetermined opening boundary, the predetermined opening boundary is surrounded by the outer edge of the positive projection of at least a part of the scoring groove in the depth direction of the scoring groove; or the predetermined opening boundary is surrounded by the connection line between multiple ends of the scoring groove; or the predetermined opening boundary is jointly surrounded by the connection line between multiple ends of the scoring groove and the outer edge of the positive projection of at least a part of the scoring groove in the depth direction of the scoring groove.

38. A battery, characterized in that, it includes the battery cell according to any one of claims 1-37.

39. An electrical device, characterized in that, it includes the battery according to claim 38, and the battery is used to supply electrical energy to the electrical device.

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