Battery cell and battery

Abstract

The utility model provides a battery cell and a battery, and relates to the technical field of energy storage. The battery cell provided by the utility model comprises a shell which comprises at least one sunken part, and two adjacent side walls of the shell are sunken towards the middle part of the shell to form the sunken part; the shell further comprises a step part, the step part comprises a first step surface and a second step surface which are connected with each other, and the plane where the first step surface is located is parallel to the bottom wall of the shell; in the width direction of the shell, the second step surface and the concave part are arranged at an interval, or the second step surface is connected with the concave part; the electrode assembly is arranged in the shell; and the tab is connected to the electrode assembly and is led out relative to one side of the shell. After the battery cell provided by the utility model is assembled in a battery, the space utilization rate in a terminal electronic product is relatively high.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a battery cell and battery. Background Technology

[0002] Polymer lithium-ion batteries possess advantages such as high energy density, long cycle life, and strong temperature adaptability. They are widely used in various consumer electronics products. As 3C consumer electronics products trend towards thinner and lighter designs, the demand for efficient space utilization is increasing, necessitating the optimization of battery structure to improve space efficiency within electronic products.

[0003] However, the current prismatic structure of polymer lithium-ion batteries limits their placement in end electronic products, resulting in low space utilization within end devices. Utility Model Content

[0004] This application provides a battery cell and a battery, wherein the battery cell has a notch for avoiding internal components of electronic products, and the battery cell has a high space utilization rate in the end electronic product after being applied to the battery.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] A first aspect of this application provides a battery cell comprising:

[0007] The housing includes at least one recess, wherein two adjacent sidewalls of the housing are recessed toward the center of the housing to form the recess; the housing also includes a stepped portion, wherein the stepped portion includes a first stepped surface and a second stepped surface connected to each other, the plane containing the first stepped surface being parallel to the bottom wall of the housing; wherein, along the width direction of the housing, the second stepped surface is spaced apart from the recess, or the second stepped surface is connected to the recess;

[0008] Electrode assemblies are disposed inside the housing;

[0009] A tab is connected to the electrode assembly and extends out from one side of the housing.

[0010] In one possible implementation, the housing includes a first sidewall, a second sidewall, and a third sidewall, the first sidewall and the second sidewall being located on opposite sides of the housing along its own length direction, the third sidewall connecting the first sidewall and the second sidewall, and the third sidewall being located on opposite sides of the housing along its own width direction.

[0011] Along the length of the housing, one end of the third sidewall forms a recess with the first sidewall or the second sidewall; or, both ends of the third sidewall form the recess with the first sidewall and the second sidewall, respectively.

[0012] In one possible implementation, the housing further includes a fourth sidewall, which is opposite to the third sidewall along the width direction of the housing and connects the first sidewall and the second sidewall. Along the length direction of the housing, one end of the fourth sidewall forms a recess with the first sidewall or the second sidewall; or, both ends of the fourth sidewall form the recess with the first sidewall and the second sidewall, respectively.

[0013] In one possible implementation, the recess includes connected arc segments and straight segments;

[0014] Along the length of the shell, the projected length L1 of the arc segment on the plane where the first sidewall is located is greater than or equal to 1 mm, and the projected length L2 of the straight segment on the plane where the first sidewall is located is greater than 0 mm.

[0015] In one possible implementation, the ratio of the sum of the projected lengths L of the arc segment and the straight segment on the plane containing the first sidewall to the width X of the shell is 3% ≤ L / X ≤ 95%.

[0016] In one possible implementation, there are two tabs, which are connected to the electrode assembly at a distance and extend relative to the first sidewall of the housing;

[0017] The sum of the projected lengths L of the arc segment and the straight segment on the plane of the first sidewall is less than W1, where W1 is the distance between the tab near the recessed side and the plane of the third sidewall.

[0018] In one possible implementation, along the width direction of the housing, the projection Y1 of the arc segment onto the plane containing the third sidewall satisfies the relationship: 0.5mm < Y1 < (Y-1)mm, where Y is the length of the housing.

[0019] In one possible implementation, along the width direction of the housing, the projection Y1 of the arc segment onto the plane containing the third sidewall satisfies the relationship Y of the length Y of the housing: 0.5% ≤ Y1 / Y ≤ 99%.

[0020] In a possible implementation, the arc segment includes a connected first arc segment and a second arc segment. The first arc segment is connected to the first side wall, and the second arc segment is connected to the straight segment. The curvature radii of the first arc segment and the second arc segment are both greater than or equal to 0.5 mm.

[0021] In a possible implementation, the length of the second step surface is the same as the length of the housing.

[0022] In a possible implementation, the second step surface and the recess are arranged at intervals. The distance X1 between the end face of the recess on the side close to the second step surface and the second step surface satisfies the condition: 0 ≤ X1 ≤ X3 - L1, where X3 is the distance between the plane of the side wall surface close to the recess in the width direction of the housing and the second step surface.

[0023] In a possible implementation, the housing further includes a top encapsulation layer and a side encapsulation layer. The top encapsulation layer covers part of the tab, and the side encapsulation layer is bent and arranged outside two opposite side walls of the housing.

[0024] In a possible implementation, the top encapsulation layer has a notch, and the notch corresponds to the recess. In the thickness direction of the housing, the projection shape of the notch on the plane of the bottom wall of the housing is rectangular, arc-shaped or triangular.

[0025] In a possible implementation, the projection shape of the notch on the plane of the bottom wall of the housing is rectangular;

[0026] The notch includes a connected first side and a second side. The recess includes a connected arc segment and a straight segment. The dimension Y2 of the first side and the projection Y1 of the arc segment on the plane of the third side wall satisfy the relationship: Y2 < Y1 + 1 mm; and / or, the dimension L3 of the second side and L2 satisfy the relationship: L3 < L2 + 1 mm.

[0027] The battery cell provided in the first aspect of the present application has at least the following beneficial effects:

[0028] By providing a recess on the side wall of the housing with a stepped portion, the stepped portion not only makes better use of the internal space of the housing, optimizes the layout of the electrode assembly, and improves the structural compactness of the housing, but also serves as a reference for the installation, positioning, and alignment of the battery cell, simplifying the alignment and fixing steps during battery cell assembly. The combination of the stepped portion and the recess on the battery cell housing, i.e., the selective design of whether the stepped surfaces of the recess and the stepped portion are connected, further enhances the spatial adaptability of the battery cell structure. This allows for more full utilization of the internal space of the terminal electronic device. When the battery using this cell is installed in the terminal device, the recess can avoid interfering with components inside the terminal device, improving the space utilization rate of the battery within the terminal device. In other words, the battery capacity is increased by increasing the available installation space for the battery.

[0029] A second aspect of this application provides a battery comprising the cell provided by any of the above-described technical solutions.

[0030] The beneficial effects of the battery provided by the second aspect of this application have all the beneficial effects of the battery cell provided by the first aspect of this application, which will not be repeated here. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the battery cell structure in related technologies;

[0033] Figure 2 for Figure 1 Enlarged structural diagram of area A in the middle;

[0034] Figure 3 This is a schematic diagram of the battery cell structure provided in an embodiment of this application;

[0035] Figure 4 for Figure 3 A top-view structural diagram;

[0036] Figure 5 for Figure 4 A magnified structural diagram of region B in the middle;

[0037] Figure 6 To show Figure 5 A schematic diagram showing the notch dimensions of the top encapsulation layer;

[0038] Figure 7 A top view of a battery cell with two recesses according to an embodiment of this application is shown;

[0039] Figure 8 A top view of a battery cell with four recesses provided for an embodiment of this application;

[0040] Figure 9 A top view showing the battery cell with the top encapsulation layer fully retained;

[0041] Figure 10 for Figure 9 A magnified view of a portion of area C in the middle;

[0042] Figure 11 for Figure 9 A schematic diagram showing the top encapsulation layer being folded;

[0043] Figure 12 To show Figure 9 A schematic diagram showing that the notch in the top encapsulation layer is arc-shaped;

[0044] Figure 13 To show Figure 9 A schematic diagram showing the triangular notch in the top encapsulation layer;

[0045] Figure 14 This is a schematic diagram of a battery cell structure where the second step surface is connected to the recessed portion, as provided in an embodiment of this application.

[0046] Explanation of reference numerals in the attached figures:

[0047] 100. Shell;

[0048] 110. Depression;

[0049] 111. Circular arc segment;

[0050] 1111, First arc segment; 1112, Second arc segment;

[0051] 112. Straight section;

[0052] 120. First sidewall;

[0053] 130. Third sidewall;

[0054] 140. Step section; 141. First step surface; 142. Second step surface;

[0055] 150. Fourth sidewall;

[0056] 200, Polar Ear;

[0057] 210. First pole ear; 220. Second pole ear;

[0058] 300. Top encapsulation layer;

[0059] 310. Gap;

[0060] 400. Side encapsulation layer.

[0061] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0062] As described in the background section, polymer lithium-ion batteries possess advantages such as high energy density, long cycle life, and strong temperature adaptability. They are widely used in various consumer electronics products. With the trend towards thinner and lighter 3C consumer electronics, the demand for efficient space utilization is increasing, necessitating the optimization of battery structure to improve space efficiency within electronic products.

[0063] In related technologies, polymer lithium-ion batteries have a square structure. However, the square structure of polymer lithium-ion batteries has poor assembly compatibility with the internal space of electronic devices, which limits the layout of the battery in the terminal electronic product. The applicant's research found that the main reason for this problem is that there are many internal components in electronic products, and the space available for battery installation is often irregular in shape. The regular square battery cannot make full use of the installation space volume.

[0064] To address the aforementioned technical problems, this application provides a battery cell. By providing a recessed portion on the side wall of a housing with a stepped portion, the stepped portion not only makes better use of the internal space of the housing, optimizes the layout of the electrode assembly, and improves the structural compactness of the housing, but also serves as a reference for the installation, positioning, and alignment of the battery cell, simplifying the alignment and fixing steps during assembly. The combination of the stepped portion and the recessed portion on the battery cell housing, i.e., the selective design of whether the stepped surfaces of the recessed portion and the stepped portion are connected, further enhances the spatial adaptability of the battery cell structure. This allows for more full utilization of the internal space of the terminal electronic device. When a battery using this cell is installed in a terminal device, the recessed portion can avoid interfering with components within the terminal device, improving the space utilization rate of the battery within the terminal device, i.e., increasing the battery capacity by increasing the available installation space.

[0065] To make the above-mentioned objectives, features, and advantages of the embodiments of this application more apparent and understandable, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0066] Combination Figures 1 to 14 The battery cell provided in this application embodiment includes: a housing 100, including at least one recess 110, wherein two adjacent sidewalls of the housing 100 are recessed toward the center of the housing 100 to form the recess 110, which is used to avoid components inside the terminal device; the housing 100 also includes a stepped portion 140, the stepped portion 140 including a first stepped surface 141 and a second stepped surface 142 connected to each other, the plane where the first stepped surface 141 is located is parallel to the bottom wall of the housing 100; wherein, along the width direction of the housing 100, the second stepped surface 142 is spaced apart from the recess 110, or the second stepped surface 142 is connected to the recess 110; an electrode assembly disposed inside the housing 100; and a tab connected to the electrode assembly and led out from one side opposite to the housing 100.

[0067] In this way, by providing a recess 110 on the side wall of the housing 100 with the stepped portion 140, the stepped portion 140 not only makes better use of the internal space of the housing 100, optimizes the layout of the electrode assembly, and improves the structural compactness of the housing 100, but also allows the stepped portion 140 to serve as a reference for the installation, positioning, and alignment of the battery cell, simplifying the alignment and fixing steps during battery cell assembly. The selection of whether the stepped portion 140 and the recess 110 on the battery cell housing 100 are connected, i.e., whether the recess 110 and the second step surface 142 of the stepped portion 140 are connected... The selective design further enhances the spatial adaptability of the battery cell structure, thereby making fuller use of the internal space of the terminal electronic device. When the battery using this cell is installed in the terminal device, the recess 110 can avoid the components inside the terminal device, improving the space utilization rate of the battery in the terminal device. That is, the battery capacity is increased by increasing the space available for battery installation. Furthermore, based on the setting of the step portion 140, the opening method of the recess 110 can be designed according to the structural shape of the space to be installed in the terminal device, meeting diverse application needs.

[0068] For example, the battery cell is a stacked core, which is disposed in the inner cavity of the housing 100. The core can be a parallelepiped structure or a stepped structure core, and the shape of the housing 100 is adapted to the shape of the core.

[0069] It should be noted that, Figure 3 In the diagram, the X direction is the width direction of the housing 100, the Y direction is the length direction of the housing 100, and the Z direction is the thickness direction of the housing 100.

[0070] In some embodiments, the housing 100 includes a first sidewall 120, a second sidewall, and a third sidewall 130. The first sidewall 120 and the second sidewall are located on opposite sides of the housing 100 along its own length direction. The third sidewall 130 connects the first sidewall 120 and the second sidewall and is located on opposite sides of the housing 100 along its own width direction. Along the length direction of the housing 100, one end of the third sidewall 130 forms a recess 110 with the first sidewall 120 or the second sidewall; or, both ends of the third sidewall 130 form recesses 110 with the first sidewall 120 and the second sidewall, respectively.

[0071] In some embodiments, two recesses 110 are provided on the first sidewall 120, and the two recesses 110 are located at both ends of the first sidewall 120 along the width direction of the housing 100.

[0072] In some embodiments, two recesses 110 are provided on the second sidewall, and the two recesses 110 are located at both ends of the second sidewall along the width direction of the housing 100.

[0073] In some embodiments, the wall segment forming the recess 110 extends and connects to the outer wall surface at one end of the sidewall.

[0074] In more examples, the housing 100 also includes a fourth sidewall 150. Along the width direction of the housing 100, the fourth sidewall 150 is opposite to the third sidewall 130. The fourth sidewall 150 connects the first sidewall and the second sidewall. Along the length direction of the housing 100, one end of the fourth sidewall 150 forms a recess 110 with the first sidewall 120 or the second sidewall.

[0075] Alternatively, the two ends of the fourth sidewall 150 form recesses 110 with the first sidewall 120 and the second sidewall, respectively.

[0076] In some embodiments, the recess 110 includes a connected arc segment 111 and a straight segment 112; along the length direction of the housing 100, the projected length L1 of the arc segment 111 on the plane where the first side wall 120 is located is greater than or equal to 1 mm, and the projected length L2 of the straight segment 112 on the plane where the first side wall 120 is located is greater than 0 mm.

[0077] For example, the projected length L1 of the arc segment 111 on the plane where the first side wall 120 is located is 1 mm or 1.5 mm, and the projected length L2 of the straight segment 112 on the plane where the first side wall 120 is located is 2 mm.

[0078] In some embodiments, the ratio of the sum of the projected lengths L of the arc segment 111 and the straight segment 112 on the plane where the first sidewall 120 is located along the length direction of the housing 100 to the width X of the housing 100 is 3% ≤ L / X ≤ 95%.

[0079] This design avoids situations where the size of the recess 110 is too small or too large, causing the arc segment 111 of the recess 110 to be too close to the chamfer of the side wall end of the shell 100 along the width direction of the shell 100. This would easily lead to stress concentration areas forming on both sides of the recess 110, thereby affecting the strength of the shell 100.

[0080] In some embodiments, there are two electrodes, namely a first electrode 210 and a second electrode 220. The two electrodes are connected to the electrode assembly at intervals and extend out relative to the first sidewall of the housing 100. The sum L of the projected lengths of the arc segment and the straight segment on the plane of the first sidewall is less than W1, where W1 is the distance between the electrode near the recess 110 and the plane of the third sidewall.

[0081] This design ensures that the sum L of the projected lengths of the arc segment 111 and the straight segment 112 on the plane of the first sidewall 120 will not be too long and thus damage the tab structure.

[0082] In some embodiments, along the width direction of the housing 100, the size of the projection Y1 of the arc segment 111 on the plane where the third sidewall 130 is located satisfies the relationship: 0.5mm < Y1 < (Y-1)mm, where Y is the length of the housing 100.

[0083] In some embodiments, along the width direction of the housing 100, the projection Y1 of the arc segment 111 on the plane where the third sidewall 130 is located satisfies the relationship with the length Y of the housing 100: 0.5% ≤ Y1 / Y ≤ 99%.

[0084] In this way, the problems of difficulty in forming the recessed part 110 or damage to the wall surface of the shell 100 due to the small size of the arc segment 111 are avoided. Also, the problem of the arc segment 111 being too large and the remaining part of the shell 100 being too narrow will affect the overall structural strength of the shell 100 and make the shell 100 prone to deformation.

[0085] In some embodiments, the arc segment 111 includes a first arc segment 1111 and a second arc segment 1112 connected together. The first arc segment 1111 is connected to the first sidewall 120, and the second arc segment 1112 is connected to the straight segment 112. The radii of curvature of the first arc segment 1111 and the second arc segment 1112 are both greater than or equal to 0.5 mm.

[0086] This configuration limits the dimensions of the first arc segment 1111 and the second arc segment 1112 to ensure the feasibility of stamping and to prevent the membrane of the housing 100 from being damaged by stamping when processing the recessed portion 110 of the housing 100.

[0087] In some embodiments, the length of the second step surface 142 is the same as the length of the housing 100. For example, the length of the second step surface 142 and the length of the housing 100 are both 70 mm.

[0088] In some examples, the second step surface 142 is spaced apart from the recess 110, and the distance X1 between the end face of the recess 110 near the second step surface 142 and the second step surface 142 satisfies the condition: 0≤X1≤X3-L1, where X3 is the distance between the plane containing the side wall surface near the recess 110 along the width direction of the housing 100 and the second step surface 142.

[0089] This design prevents the edge of the recess 110 from being too close to the sidewall of the housing 100 along the width direction, which would affect the punching performance.

[0090] In more examples, the housing 100 also includes a top encapsulation layer 300 and a side encapsulation layer 400, the top encapsulation layer 300 covering part of the tabs, and the side encapsulation layer 400 bent and disposed on the outer sides of two opposite sidewalls of the housing 100.

[0091] In this way, the top encapsulation layer 300 and the side encapsulation layer 400 can effectively prevent electrolyte leakage inside the battery cell, ensure the battery cell's sealing performance, and thus improve the battery cell's safety and stability. Moreover, the encapsulation layer can also enhance the mechanical strength of the housing 100, preventing the battery cell from being deformed or damaged by external impacts or pressure during use. At the same time, the encapsulation layer can prevent moisture and impurities in the external environment from entering the battery cell, thereby avoiding possible short circuits and other electrical faults.

[0092] In some embodiments, the top encapsulation layer 300 has a notch 310, which is provided corresponding to the recess 110. The side of the notch 310 includes a first straight side and a second straight side that are orthogonal to each other. The first straight side extends along the length direction of the housing 100, and the second straight side extends along the width direction of the housing 100. Along the thickness direction of the housing 100, the projection shape of the notch 310 on the plane where the bottom wall of the housing 100 is located is rectangular, arc-shaped, or triangular.

[0093] Furthermore, when the first side of the notch 310 is parallel to the width direction of the housing 100, the first side is flush with the outer wall surface of the third sidewall 130 along the width direction of the housing 100. When the first side of the notch 310 intersects with the width direction of the housing 100, the first side is flush with the outer wall surface of the third sidewall 130, or the first side is on the right side of the third sidewall 130.

[0094] In some embodiments, the length of the top encapsulation layer 300300 extending relative to the housing 100 along the length direction of the housing 100 is greater than or equal to 1 mm, so as to ensure the encapsulation and sealing effect of the housing 100.

[0095] In some embodiments, the projection shape of the notch on the plane of the bottom wall of the housing 100 is rectangular; the notch includes a connected first side and a second side, the recess 110 includes a connected arc segment and a straight segment, and the dimension Y2 of the first side and the projection Y1 of the arc segment on the plane of the third side wall satisfy the relationship: Y2 < Y1 + 1 mm; and / or, the dimensions L3 and L2 of the second side satisfy the relationship: L3 < L2 + 1 mm.

[0096] In this way, for the dimension limitation of the notch 310 in the length and width directions of the housing 100, it is avoided that the protruding part 310 of the encapsulation layer 300 is cut off too much, which affects the sealing effect of the housing 100.

[0097] On the premise of ensuring the effective sealing width for self-sealing of the battery cell provided by the embodiments of the present application, the recess 110 is provided in the circumferential direction of the housing 100, which improves the space adaptability of the battery cell and can make more full use of the space of the terminal electronic product. While meeting the thinner design of the terminal product, the capacity of the battery cell is increased.

[0098] In a second aspect, the embodiments of the present application provide a battery, which includes the battery cell provided by any one of the embodiments of the first aspect. The battery has all the beneficial effects of the battery cell of the first aspect and will not be elaborated here.

[0099] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0100] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0101] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0102] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0103] The various embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0104] It should be noted that the embodiments referred to in the specification, such as "one embodiment," "embodiment," "exemplary embodiment," and "some embodiments," may include specific features, structures, or characteristics, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery cell, characterized in that, include: The housing includes at least one recess, wherein two adjacent sidewalls of the housing are recessed toward the center of the housing to form the recess; the housing also includes a stepped portion, wherein the stepped portion includes a first stepped surface and a second stepped surface connected to each other, the plane containing the first stepped surface being parallel to the bottom wall of the housing; wherein, along the width direction of the housing, the second stepped surface is spaced apart from the recess, or the second stepped surface is connected to the recess; Electrode assemblies are disposed inside the housing; A tab is connected to the electrode assembly and extends out from one side of the housing.

2. The battery cell according to claim 1, characterized in that, The housing includes a first sidewall, a second sidewall, and a third sidewall. The first sidewall and the second sidewall are located on opposite sides of the housing along its own length direction. The third sidewall connects the first sidewall and the second sidewall and is located on opposite sides of the housing along its own width direction. Along the length of the housing, one end of the third sidewall forms a recess with the first sidewall or the second sidewall; or, both ends of the third sidewall form the recess with the first sidewall and the second sidewall, respectively.

3. The battery cell according to claim 2, characterized in that, The housing further includes a fourth sidewall. Along the width direction of the housing, the fourth sidewall is opposite to the third sidewall and connects the first sidewall and the second sidewall. Along the length direction of the housing, one end of the fourth sidewall forms a recess with the first sidewall or the second sidewall; or, both ends of the fourth sidewall form the recess with the first sidewall and the second sidewall, respectively.

4. The battery cell according to any one of claims 2-3, characterized in that, The recessed portion includes connected arc segments and straight segments; Along the length of the shell, the projected length L1 of the arc segment on the plane where the first sidewall is located is greater than or equal to 1 mm, and the projected length L2 of the straight segment on the plane where the first sidewall is located is greater than 0 mm.

5. The battery cell according to claim 4, characterized in that, Along the length of the shell, the ratio of the sum of the projected lengths L of the arc segment and the straight segment on the plane containing the first sidewall to the width X of the shell is 3% ≤ L / X ≤ 95%.

6. The battery cell according to claim 5, characterized in that, There are two electrodes, which are connected to the electrode assembly at intervals and extend out relative to the first sidewall of the housing; The sum of the projected lengths L of the arc segment and the straight segment on the plane of the first sidewall is less than W1, where W1 is the distance between the tab near the recessed side and the plane of the third sidewall.

7. The battery cell according to claim 6, characterized in that, Along the width direction of the shell, the projection Y1 of the arc segment on the plane where the third side wall is located satisfies the following relationship: 0.5mm < Y1 < (Y-1)mm, where Y is the length of the shell.

8. The battery cell according to claim 7, characterized in that, Along the width direction of the shell, the projection Y1 of the arc segment on the plane where the third side wall is located satisfies the relationship Y of the length Y of the shell: 0.5% ≤ Y1 / Y ≤ 99%.

9. The battery cell according to claim 4, characterized in that, The arc segment includes a connected first arc segment and a second arc segment. The first arc segment is connected to the first side wall, and the second arc segment is connected to the straight segment. The radius of curvature of both the first arc segment and the second arc segment is greater than or equal to 0.5 mm.

10. The battery cell according to any one of claims 1-3, characterized in that, The length of the second step surface is the same as the length of the housing.

11. The battery cell according to claim 10, characterized in that, The second step surface and the recess are spaced apart. The distance X1 between the end surface of the recess on the side close to the second step surface and the second step surface satisfies the condition: 0 ≤ X1 ≤ X3 - L1, where X3 is the distance between the plane of the side wall surface close to the recess in the width direction of the housing and the second step surface.

12. The battery cell according to claim 4, characterized in that, The housing further includes a top encapsulation layer and side encapsulation layers. The top encapsulation layer covers part of the tab, and the side encapsulation layers are bent and disposed outside two opposite side walls of the housing.

13. The battery cell according to claim 12, characterized in that, The top encapsulation layer has a notch corresponding to the recess. In the thickness direction of the housing, the projection shape of the notch on the plane of the bottom wall of the housing is rectangular, arc-shaped or triangular.

14. The battery cell according to claim 13, characterized in that, The projection shape of the notch on the plane of the bottom wall of the housing is rectangular; The notch includes a connected first side and a second side. The recess includes a connected arc segment and a straight segment. The dimension Y2 of the first side and the projection Y1 of the arc segment on the plane of the third side wall satisfy the relationship: Y2 < Y1 + 1 mm; and / or, the dimension L3 of the second side and L2 satisfy the relationship: L3 < L2 + 1 mm.

15. A battery, characterized in that, Including the battery cell according to any one of claims 1-14.

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