Battery cell and electric equipment

Abstract

The embodiment of the invention provides a battery cell and electric equipment. The battery cell comprises a shell and an electrode assembly, and the electrode assembly is accommodated in the shell; the electrode assembly comprises a diaphragm, and a first pole piece group and a second pole piece group which are laminated in a first direction. The first pole piece group comprises a plurality of first pole pieces which are stacked in the first direction; the second pole piece group comprises a plurality of second pole pieces which are stacked in the first direction, and the length of the second pole piece group is greater than that of the first pole piece group in the second direction; the diaphragm comprises a plurality of first folding parts arranged at intervals along a first direction, a plurality of second folding parts arranged at intervals along the first direction, at least one first connecting part, at least one second connecting part and a third connecting part, a first pole piece is arranged between every two adjacent first folding parts, and the first folding parts are connected through the first connecting parts; a second pole piece is arranged between every two adjacent second folding parts, and the second folding parts are connected through a second connecting part; and the third connecting parts are connected with the adjacent first folding parts and second folding parts.

Description

Technical Field

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

[0002] In recent years, with the rapid development of new energy technologies, batteries have been widely used in electronic equipment, electric vehicles, electric two-wheelers, power tools and other electrical equipment.

[0003] As the application scenarios of battery cells increase, the shape of the battery cells also changes to meet different setting environments. In the same battery cell, multiple electrode groups of different sizes will be set, and the two adjacent electrode groups in the electrode group need to be separated by a diaphragm; multiple electrode groups of different sizes need to be hot-pressed separately, and hot-pressed again when multiple electrode groups are compositely assembled, so that the thickness of some diaphragms is reduced due to multiple hot pressing, which affects the reliability of the battery cell. Therefore, how to improve the reliability of the battery cell is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The embodiments of the present application provide a battery cell and an electrical device, which can improve the reliability of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, which includes a housing and an electrode assembly, wherein the electrode assembly is accommodated in the housing; the electrode assembly includes a first electrode group, a second electrode group and a diaphragm. The first electrode group includes a plurality of first electrode sheets stacked along a first direction; the first electrode group and the second electrode group are stacked along the first direction; the second electrode group includes a plurality of second electrode sheets stacked along the first direction; along the second direction, the length of the second electrode group is greater than the length of the first electrode group, and the second direction is perpendicular to the first direction; the diaphragm includes a plurality of first folding portions, a plurality of second folding portions, at least one first connecting portion, at least one second connecting portion and a third connecting portion; along the second direction, the length of the second folding portion is greater than the first folding portion; the plurality of first folding portions are arranged at intervals along the first direction, one first electrode sheet is arranged between two adjacent first folding portions, and the first connecting portion connects two adjacent first folding portions; the plurality of second folding portions are arranged at intervals along the first direction, one second electrode sheet is arranged between two adjacent second folding portions, and the second connecting portion connects two adjacent second folding portions; the third connecting portion connects the adjacent first folding portions and the second folding portions.

[0006] According to the battery cell of the embodiment of the present application, the lengths of the second electrode group and the first electrode group in the second direction are different, so that the shape of the battery cell can adapt to the shape of the battery compartment of the electrical device. The diaphragm is a continuous structure, wherein the first folding portion is stacked with a plurality of first electrode sheets, and two adjacent first folding portions are connected by a first connecting portion; the second folding portion is stacked with a plurality of second electrode sheets, and two adjacent second folding portions are connected by a second connecting portion; and adjacent first folding portions and second folding portions are connected by a third connecting portion. When the diaphragm of the continuous structure is stacked and compounded with a plurality of first electrode sheets and second electrode sheets, the diaphragm can wrap the ends of the first electrode sheets and the second electrode sheets, and form an insulating isolation between the ends of the first electrode sheets and the second electrode sheets and the outer shell, so that the distance between the ends of the first electrode sheets and the second electrode sheets and the outer shell can be designed to be smaller. On the one hand, the risk of short circuit between the electrode assembly and the outer shell is reduced, thereby improving the safety performance of the battery cell. On the other hand, the space utilization rate in the outer shell is improved, and the energy density of the battery cell is improved. At the same time, the diaphragm with a continuous structure can complete the stacking of multiple electrode plate groups of different sizes in one stacking process, thereby facilitating the hot pressing of the electrode plates and diaphragms in the same electrode plate group in one hot pressing, and completing the hot pressing of the composite assembly of multiple electrode plate groups of different sizes. Compared with the implementation method of hot pressing multiple electrode plate groups of different sizes separately and hot pressing them again when the multiple electrode plate groups are compositely assembled, the number of hot pressing times of the electrode assembly is reduced. On the one hand, the number of hot pressing devices required for hot pressing of the electrode assembly is reduced, thereby reducing the investment in production costs; on the other hand, the number of hot pressing times of the diaphragm located in the electrode plate group is reduced, thereby reducing the risk of partial smaller thickness of the diaphragm due to multiple hot pressings, thereby reducing the risk of reduced insulation withstand voltage performance of the battery cell due to the smaller partial thickness of the diaphragm, and improving the reliability of the battery cell.

[0007] In some embodiments of the first aspect of the present application, one of the multiple first pole pieces that is closest to the second pole piece group is a first end pole piece, and one of the multiple second pole pieces that is closest to the first pole piece group is a second end pole piece; the second end pole piece has opposite polarity to the first end pole piece, and a first folding portion is arranged between the second end pole piece and the first end pole piece.

[0008] In one or more of the above optional embodiments, since the length of the second folded portion in the second direction is greater than the length of the first folded portion, and then when the sizes of the second folded portion and the first folded portion in other directions are consistent, the volume of the second folded portion is greater than the volume of the first folded portion. Therefore, relative to providing a second folded portion between the second end pole piece and the first end pole piece, providing a first folded portion between the second end pole piece and the first end pole piece reduces the volume of the diaphragm, thereby reducing the space occupied by the diaphragm in the outer shell, making it easier to provide more active materials in the outer shell, and thereby improving the energy density of the battery cell.

[0009] In some embodiments of the first aspect of the present application, the first end pole piece has a first end and a second end relatively set in the second direction, and the second pole piece in the second pole piece group with the same polarity as the first end pole piece has a third end and a fourth end relatively set in the second direction; along the second direction, the fourth end is flush with the second end, and the third end extends beyond the first end; and the first connecting portion wraps around the first end.

[0010] In one or more optional embodiments above, along the second direction, the length of the second electrode group is greater than the length of the first electrode group, and along the second direction, the fourth end is flush with the second end, and the third end exceeds the first end, so that a portion of the second end electrode exceeds the first end, and the first connecting portion wraps the first end. Therefore, during hot pressing, the first connecting portion can perform structural positioning on the first end electrode, thereby reducing the risk of misalignment of the electrode assembly stacking caused by the first end electrode moving along the second direction close to the area of ​​the second end electrode exceeding the first end, and reducing the risk of internal short circuit of the electrode assembly caused by the first end electrode moving along the second direction so that the first end electrode and the second end electrode contact the area exceeding the first end, thereby improving the production yield rate of the battery cell.

[0011] In some embodiments of the first aspect of the present application, one of the multiple first pole pieces that is closest to the second pole piece group is a first end pole piece, and one of the multiple second pole pieces that is closest to the first pole piece group is a second end pole piece; the second end pole piece has opposite polarity to the first end pole piece, and a second folding portion is provided between the second end pole piece and the first end pole piece.

[0012] In one or more of the above optional embodiments, the second folding portion covers a partial area of ​​the second end pole piece that extends beyond the first end pole piece in the second direction, thereby reducing the risk of short circuit between the first end pole piece and the partial area of ​​the second end pole piece that extends beyond the first end pole piece in the second direction, thereby improving the reliability of the battery cell.

[0013] In some embodiments of the first aspect of the present application, the first end pole piece has a first end and a second end relatively set in the second direction, and the second pole piece in the second pole piece group with the same polarity as the first end pole piece has a third end and a fourth end relatively set in the second direction; along the second direction, the fourth end is flush with the second end, and the third end extends beyond the first end; and the third connecting portion wraps the second end.

[0014] In one or more of the above optional embodiments, the third connecting portion wraps around the second end, thereby reducing the risk of short circuit between the second end and the outer shell, thereby improving the reliability of the battery cell. At the same time, when the third connecting portion wraps around the second end, the gap between the second end and the outer shell in the second direction can be set smaller, thereby improving the space utilization inside the outer shell and improving the energy density of the battery cell.

[0015] In some embodiments of the first aspect of the present application, one of the multiple second pole pieces that is closest to the first pole piece group is a second end pole piece; the second end pole piece is a positive pole piece, and the second end pole piece includes a first area overlapping with the positive pole piece in the first pole piece group and a second area that does not overlap with the positive pole piece in the first pole piece group; or, the second end pole piece is a negative pole piece, and the second end pole piece includes a first area overlapping with the negative pole piece in the first pole piece group and a second area that does not overlap with the negative pole piece in the first pole piece group; along the first direction, active material layers are arranged on both sides of the first area, and the second area has an active material layer only on the side away from the first pole piece group.

[0016] In one or more of the above optional embodiments, the second region of the second end electrode sheet is provided with an active material layer only on the side away from the first electrode sheet group, thereby reducing the active material that does not exert its capacity and avoiding the space occupied by the active material that does not exert its capacity, further reducing the energy density loss of the battery cell in the first direction, and at the same time reducing the use of active material, reducing the production cost of the second end electrode sheet, and thereby reducing the production cost of the battery cell.

[0017] In some embodiments of the first aspect of the present application, one of the multiple second pole pieces that is closest to the first pole piece group is a second end pole piece; the second end pole piece is a positive pole piece, and the second end pole piece includes a first area overlapping with the positive pole piece in the first pole piece group and a second area not overlapping with the positive pole piece in the first pole piece group; or, the second end pole piece is a negative pole piece, and the second end pole piece includes a first area overlapping with the negative pole piece in the first pole piece group and a second area not overlapping with the negative pole piece in the first pole piece group; along the first direction, active material layers are arranged on both sides of the first area, and active material layers are arranged on both sides of the second area.

[0018] In one or more of the above optional embodiments, active material layers are provided on both sides of the second region of the second end pole piece, so that when coating the side of the second end pole piece facing the first pole piece group, the active material layer can be simultaneously coated on the first region and the second region of the second end pole piece, thereby avoiding the problem of pole piece warping caused by different tensions on the two sides due to the active material layer being provided on only one side of the second region.

[0019] In some embodiments of the first aspect of the present application, the one of the multiple first pole pieces that is farthest from the second pole piece group is a third end pole piece, and the third end pole piece is provided with an active material layer only on the side facing the second pole piece group; the one of the multiple second pole pieces that is farthest from the first pole piece group is a fourth end pole piece, and the fourth end pole piece is provided with an active material layer only on the side facing the first pole piece group.

[0020] In one or more optional embodiments above, the third end pole piece is provided with an active material layer only on the side facing the second pole piece group, which can reasonably utilize the internal space of the shell and facilitate the improvement of the energy density of the battery cell; at the same time, the third end pole piece is not provided with an active material layer on the side facing away from the second pole piece group, so as to facilitate the bonding with other components (such as insulating parts, shells, etc.). The fourth end pole piece is provided with an active material layer only on the side facing the first pole piece group, which can reasonably utilize the internal space of the shell and facilitate the improvement of the energy density of the battery cell; at the same time, the fourth end pole piece is not provided with an active material layer on the side facing away from the first pole piece group, so as to facilitate the bonding with other components (such as insulating parts, shells, etc.).

[0021] In some embodiments of the first aspect of the present application, the shell includes a first wall and a second wall arranged opposite to each other along the first direction, the first wall includes a first sub-wall, a second sub-wall and a first connecting wall, the second sub-wall protrudes from the first wall along the direction away from the second wall, and the first connecting wall connects the first sub-wall and the second sub-wall; the second pole piece group is arranged between the first sub-wall and the second wall, and the first pole piece group is arranged between the second sub-wall and the second pole piece group.

[0022] In one or more of the above optional embodiments, the second sub-wall protrudes from the first sub-wall in a direction away from the second wall, and the first connecting wall connects the first sub-wall and the second sub-wall to form a step on the surface of the first wall away from the second wall, and the step is sufficient for placing components, so that the battery cell can occupy other space in the battery compartment of the electrical equipment except for the space where the components are located, thereby improving the space utilization of the battery compartment and further improving the compactness of the internal structure of the electrical equipment; the second pole piece group is arranged between the first sub-wall and the second wall, and the first pole piece group is arranged between the second sub-wall and the second pole piece group, so that the electrode assembly can fully occupy the internal space of the outer shell, so that when the volume of the battery compartment is constant, the energy density of the battery cell is higher, which is beneficial to improving the endurance of the electrical equipment.

[0023] In a second aspect, the present application further provides an electrical device, which includes a battery cell provided according to any of the above embodiments, and the battery cell is used to provide electrical energy.

[0024] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 An exploded diagram of the structure of a battery cell provided in some embodiments of the present application;

[0027] Figure 2 A cross-sectional view of a battery cell provided in some embodiments of the present application;

[0028] Figure 3 A schematic diagram of the structure of the membrane after expansion provided in some embodiments of the present application;

[0029] Figure 4 A schematic diagram of the structure of a folded diaphragm provided in some embodiments of the present application;

[0030] Figure 5 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0031] Figure 6 for Figure 5 The enlarged view of point A in the middle;

[0032] Figure 7 A schematic diagram of the structure of an electrode assembly provided in some other embodiments of the present application;

[0033] Figure 8 for Figure 7 The enlarged view of point B in the middle;

[0034] Fig. 9 A schematic diagram of the structure of an electrode assembly provided in some other embodiments of the present application;

[0035] Fig.10 A schematic diagram of the structure of an electrode assembly provided in some further embodiments of the present application.

[0036] Icon: 100 - battery cell; 10 - housing; 10A - second step; 11 - first wall; 111 - first sub-wall; 112 - second sub-wall; 113 - first connecting wall; 12 - second wall;

[0037] 20-electrode assembly; 20A-first step; 21-first electrode group; 211-first electrode; 211a-first positive electrode; 211b-first negative electrode; 212-first end electrode; 212A-first end; 212B-second end; 213-third end electrode; 22-second electrode group; 221-second electrode; 221a-second positive electrode; 221b-second negative electrode; 221c-third end; 221d-fourth end; 222-second end electrode; 222A-first region; 222B-second region; 223-fourth end electrode; 23-diaphragm; 231-first folding portion; 232-second folding portion; 233-first connecting portion; 234-second connecting portion; 235-third connecting portion; 24-active material layer;

[0038] X-first direction; Y-second direction; Z-third direction. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. 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 and secondary relationship.

[0041] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0042] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0044] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0045] The term "multiple" as used in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0046] The "overlap" in this application includes not only complete overlap, but also possible process errors within a range of ±0.5 mm.

[0047] The "overlap" that appears in this application not only includes complete overlap, but may also have process errors, with an error range of ±0.5mm. The battery cell includes a casing, an electrode assembly and an electrolyte. The casing is used to contain the electrode assembly and the electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet and a diaphragm. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The material of the diaphragm can be polypropylene or polyethylene, etc., which is used to separate the positive electrode sheet and the negative electrode sheet to reduce the risk of short circuit between the positive and negative electrodes.

[0048] At present, the appearance of electrical equipment is diverse. In order to adapt to the appearance of the product and the layout of the internal structure, some components need to be set in the battery compartment. The battery cell is generally arranged in a regular rectangular parallelepiped. If the components are set in the battery compartment, the size of the battery cell needs to be smaller than the size of the battery compartment to reserve space for the components in the battery compartment. For example, space is reserved for setting components in the length (or width) direction of the battery cell. The electrode assembly includes a first pole piece group and a second pole piece group. The length of the first pole piece group is less than the length of the second pole piece group. Two adjacent pole pieces in the pole piece group need to be separated by a diaphragm. When hot pressing the electrode assembly, multiple pole piece groups of different sizes need to be hot pressed separately, and hot pressed again when multiple pole piece groups are compositely assembled, so that the thickness of part of the diaphragm is reduced due to multiple hot pressing, and then the insulation strength of the diaphragm is reduced, so that the reliability of the battery cell is poor.

[0049] In order to solve the problem that multiple hot pressings cause the thickness of part of the diaphragm to decrease, thereby reducing the insulation strength of the diaphragm, and thus making the reliability of the battery cell poor, the embodiment of the present application provides a battery cell, including a shell and an electrode assembly, the electrode assembly is accommodated in the shell; the electrode assembly includes a first electrode group, a second electrode group and a diaphragm. The first electrode group includes a plurality of first electrodes stacked along a first direction; the first electrode group and the second electrode group are stacked along the first direction, the second electrode group includes a plurality of second electrodes stacked along the first direction, along the second direction, the length of the second electrode group is greater than the length of the first electrode group, and the second direction is perpendicular to the first direction; the diaphragm includes a plurality of first folding parts, a plurality of second folding parts, at least one first connecting part, at least one second connecting part and a third connecting part, the plurality of first folding parts are arranged at intervals along the first direction, a first electrode is arranged between two adjacent first folding parts, and the first connecting part connects the two adjacent first folding parts; the plurality of second folding parts are arranged at intervals along the first direction, a second electrode is arranged between two adjacent second folding parts, and the second connecting part connects the two adjacent second folding parts; the third connecting part connects the adjacent first folding parts and the second folding parts.

[0050] In such a battery cell, the lengths of the second electrode group and the first electrode group in the second direction are different, so that the shape of the battery cell can adapt to the shape of the battery compartment of the electrical device. The diaphragm is a continuous structure, wherein the first folding portion is stacked with a plurality of first electrode sheets, and two adjacent first folding portions are connected by a first connecting portion; the second folding portion is stacked with a plurality of second electrode sheets, and two adjacent second folding portions are connected by a second connecting portion; and adjacent first folding portions and second folding portions are connected by a third connecting portion. When the diaphragm of the continuous structure is stacked and compounded with a plurality of first electrode sheets and second electrode sheets, the diaphragm can wrap the ends of the first electrode sheets and the second electrode sheets, and form an insulating isolation between the ends of the first electrode sheets and the second electrode sheets and the outer shell, so that the distance between the ends of the first electrode sheets and the second electrode sheets and the outer shell can be designed to be smaller. On the one hand, the risk of short circuit between the electrode assembly and the outer shell is reduced, thereby improving the safety performance of the battery cell. On the other hand, the space utilization rate in the outer shell is improved, and the energy density of the battery cell is improved. At the same time, the diaphragm with a continuous structure can complete the stacking of multiple electrode plate groups of different sizes in one stacking process, thereby facilitating the hot pressing of the electrode plates and diaphragms in the same electrode plate group in one hot pressing, and completing the hot pressing of the composite assembly of multiple electrode plate groups of different sizes. Compared with the implementation method of hot pressing multiple electrode plate groups of different sizes separately and hot pressing them again when the multiple electrode plate groups are compositely assembled, the number of hot pressing times of the electrode assembly is reduced. On the one hand, the number of hot pressing devices required for hot pressing of the electrode assembly is reduced, thereby reducing the investment in production costs; on the other hand, the number of hot pressing times of the diaphragm located in the electrode plate group is reduced, thereby reducing the risk of partial smaller thickness of the diaphragm due to multiple hot pressings, thereby reducing the risk of reduced insulation withstand voltage performance of the battery cell due to the smaller partial thickness of the diaphragm, and improving the reliability of the battery cell.

[0051] The embodiments of the present application provide an electrical device that uses a battery cell as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc.

[0052] It should be noted that each battery cell can be a secondary battery or a primary battery, for example, a lithium ion battery, a sodium ion battery or a magnesium ion battery. In the present application, the battery cell is a rectangular parallelepiped structure.

[0053] The structural schematic diagram of the battery cell provided in the embodiment of the present application will be described below in conjunction with the figures.

[0054] like Figure 1-Figure 5As shown, the embodiment of the present application provides a battery cell 100, which includes a housing 10 and an electrode assembly 20, and the electrode assembly 20 is accommodated in the housing 10; the electrode assembly 20 includes a first electrode plate group 21, a second electrode plate group 22 and a diaphragm 23. The first electrode plate group 21 includes a plurality of first electrode plates 211 stacked along a first direction X; the first electrode plate group 21 and the second electrode plate group 22 are stacked along the first direction X, and the second electrode plate group 22 includes a plurality of second electrode plates 221 stacked along the first direction X, and along the second direction Y, the length of the second electrode plate group 22 is greater than the length of the first electrode plate group 21, and the second direction Y is perpendicular to the first direction X; the diaphragm 23 includes a plurality of first folding portions 231, a plurality of second folding portions 232, at least one first connecting portion 233, at least one second connecting portion 234 and a third connecting portion 235, along the second direction Y, the length of the second folding portion 232 is greater than that of the first folding portion 231, multiple first folding portions 231 are arranged at intervals along the first direction X, a first pole piece 211 is arranged between two adjacent first folding portions 231, and a first connecting portion 233 connects two adjacent first folding portions 231; multiple second folding portions 232 are arranged at intervals along the first direction X, a second pole piece 221 is arranged between two adjacent second folding portions 232, and a second connecting portion 234 connects two adjacent second folding portions 232; a third connecting portion 235 connects adjacent first folding portions 231 and second folding portions 232.

[0055] like Figure 1 and Figure 2 As shown, the housing 10 is a component in the battery cell 100 for providing a receiving space to accommodate the electrode assembly 20 and provide a relatively stable working environment for the electrode assembly 20. The electrode assembly 20 is received in the housing 10.

[0056] Exemplarily, the shell 10 can be a hard shell, such as a stainless steel shell or an aluminum hard shell, forming a steel shell battery or an aluminum shell battery; the shell 10 can also be formed of a softer material, such as an aluminum-plastic film or a steel-plastic film, forming a soft-pack battery cell.

[0057] like Figure 5 As shown, in some embodiments, the electrode assembly 20 is a laminated structure, and the plurality of first electrode sheets 211 in the first electrode sheet group 21 and the plurality of second electrode sheets 221 in the second electrode sheet group 22 are stacked along the thickness direction of the electrode assembly 20. The first direction X may be parallel to the thickness direction of the electrode assembly 20, and the second direction Y may be perpendicular to the thickness direction of the electrode assembly 20. For example, the second direction Y may be parallel to the length direction of the battery cell 100, or the second direction Y may be parallel to the width direction of the battery cell 100.

[0058] like Figure 5As shown, the plurality of first pole pieces 211 include a first positive pole piece 211a and a first negative pole piece 211b, and the first positive pole piece 211a and the first negative pole piece 211b are arranged alternately. The plurality of second pole pieces 221 include a second positive pole piece 221a and a second negative pole piece 221b, and the second positive pole piece 221a and the second negative pole piece 221b are arranged alternately.

[0059] In the embodiment of the present application, the positive electrode plate includes a positive electrode current collector and an active material layer 24, at least one side of the positive electrode current collector is provided with an active material layer 24, the material of the positive electrode current collector may include aluminum, and the active material layer 24 may be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer 24, at least one side of the negative electrode current collector is provided with a negative electrode active material layer 24, the material of the negative electrode current collector may include copper, and the negative electrode active material may be carbon or silicon, etc.

[0060] like Figure 3 and Figure 4 For convenience in showing the range of the first folding portion 231, the first folding portion 231, the first connecting portion 233, the second connecting portion 234 and the third connecting portion 235, please refer to Figure 3 In the figure, the first folding portion 231, the first folding portion 231, the first connecting portion 233, the second connecting portion 234 and the third connecting portion 235 are marked with dotted lines. It should be noted that the dotted lines are only for the convenience of showing the range of the first folding portion 231, the first folding portion 231, the first connecting portion 233, the second connecting portion 234 and the third connecting portion 235, and do not represent any entity meaning. The diaphragm 23 is a continuous structure. Along the extension direction of the diaphragm 23, a plurality of first folding portions 231 and a plurality of second folding portions 232 are arranged in sequence. Adjacent first folding portions 231 are connected by the first connecting portion 233, adjacent second folding portions 232 are connected by the second connecting portion 234, and adjacent first folding portions 231 and second folding portions 232 are connected by the third connecting portion 235.

[0061] like Figure 5 As shown, after lamination, the first folding portion 231 can be parallel to the first pole piece 211, and multiple first folding portions 231 are arranged at intervals along the first direction X, and along the first direction X, a first pole piece 211 is arranged between two adjacent first folding portions 231; the second folding portion 232 can be parallel to the second pole piece 221, and multiple second folding portions 232 are arranged at intervals along the first direction X, and along the first direction X, a second pole piece 221 is arranged between two adjacent second folding portions 232; along the first direction X, a first pole piece 211 or a second pole piece 221 is arranged between adjacent first folding portions 231 and second folding portions 232.

[0062] It can be understood that the first folding portion 231 can cover the surface of the first pole piece 211 in the first direction X to isolate two adjacent first pole pieces 211 in the first direction X; the second folding portion 232 can cover the surface of the second pole piece 221 in the first direction X to isolate two adjacent second pole pieces 221 in the first direction X.

[0063] like Figure 5 As shown, in some embodiments, when the number of the first connection part 233 is one, the number of the first folding parts 231 is two, and the two first folding parts 231 are connected by the first connection part 233; or, the number of the first connection parts 233 and the number of the first folding parts 231 are multiple, the number of the first folding parts 231 is greater than the number of the first connection parts 233, and two adjacent first folding parts 231 are connected by the first connection part 233. When the number of the second connection parts 234 is one, the number of the second folding parts 232 is two, and the two second folding parts 232 are connected by the second connection part 234; or, the number of the second connection parts 234 and the number of the second folding parts 232 is multiple, the number of the second folding parts 232 is greater than the number of the second connection parts 234, and two adjacent second folding parts 232 are connected by the second connection part 234. Adjacent first folding parts 231 and second folding parts 232 are connected by third connection parts 235.

[0064] Since the diaphragm 23 is a continuous structure, when the diaphragm 23 is compounded with a plurality of first electrode sheets 211 and a plurality of second electrode sheets 221, the diaphragm 23 can wrap the ends of the first electrode sheets 211 and the second electrode sheets 221. For example, a first connecting portion 233 can be provided between one end of the first negative electrode sheet 211b and the outer shell 10 to form an insulating isolation between the end of the first negative electrode sheet 211b and the outer shell 10. In this case, the distance between the end and the outer shell 10 can be smaller. A second connecting portion 234 can be provided between one end of the second negative electrode sheet 221b and the outer shell 10 to form an insulating isolation between the end of the second negative electrode sheet 221b and the outer shell 10. In this case, the distance between the end and the outer shell 10 can be smaller. On the one hand, the risk of short circuit between the first negative electrode sheet 211b and the second negative electrode sheet 221b and the outer shell 10 is reduced, thereby improving the safety performance of the battery cell 100. On the other hand, the space utilization rate in the outer shell 10 is improved, thereby improving the energy density of the battery cell 100. Among them, one end of the first negative electrode plate 211b may be one end of the first negative electrode plate 211b in the second direction Y, or one end of the first negative electrode plate 211b in the third direction Z. One end of the second negative electrode plate 221b may be one end of the second negative electrode plate 221b in the second direction Y, or one end of the second negative electrode plate 221b in the third direction Z. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0065] It should be noted that the diaphragm 23 wraps the end of the first pole piece 211, which means that the first connecting portion 233 of the diaphragm 23 and the two adjacent first folding portions 231 form a storage space, or the third connecting portion 235 and the adjacent first folding portion 231 and the second folding portion 232 form a storage space, and the end of the first pole piece 211 is accommodated in the storage space. Exemplarily, the first connecting portion 233 or the third connecting portion 235 can be attached to the end of the first pole piece 211, or there can be a gap between the first connecting portion 233 or the third connecting portion 235 and the end of the first pole piece 211.

[0066] The diaphragm 23 wraps the end of the second pole piece 221, which means that the second connecting portion 234 of the diaphragm 23 and the two adjacent second folding portions 232 form a receiving space, or the third connecting portion 235 and the adjacent first folding portion 231 and second folding portion 232 form a receiving space, and the end of the second pole piece 221 is received in the receiving space. Exemplarily, the second connecting portion 234 or the third connecting portion 235 may fit with the end of the second pole piece 221, or there may be a gap between the second connecting portion 234 or the third connecting portion 235 and the end of the second pole piece 221.

[0067] The diaphragm 23 can also be used to separate the first pole piece group 21 and the second pole piece group 22. Exemplarily, if a first folding portion 231 is provided between the first pole piece group 21 and the second pole piece group 22, a second pole piece 221 is provided between adjacent first folding portions 231 and second folding portions 232; if a second folding portion 232 is provided between the first pole piece group 21 and the second pole piece group 22, a first pole piece 211 is provided between adjacent first folding portions 231 and second folding portions 232.

[0068] For example, the material of the diaphragm 23 may be polypropylene or polyethylene.

[0069] In one or more optional embodiments above, the second electrode group 22 and the first electrode group 21 have different lengths in the second direction Y, so that the shape of the battery cell 100 can adapt to the shape of the battery compartment of the electrical device. The diaphragm 23 is a continuous structure, wherein the first folding portion 231 is stacked with a plurality of first electrode sheets 211, and two adjacent first folding portions 231 are connected by a first connecting portion 233; the second folding portion 232 is stacked with a plurality of second electrode sheets 221, and two adjacent second folding portions 232 are connected by a second connecting portion 234; and the adjacent first folding portions 231 and second folding portions 232 are connected by a third connecting portion 235. When the diaphragm 23 with a continuous structure is stacked and compounded with multiple first pole pieces 211 and second pole pieces 221, the diaphragm 23 can wrap the ends of the first pole piece 211 and the second pole piece 221, and form an insulating isolation between the ends of the first pole piece 211 and the second pole piece 221 and the outer shell 10, so that the distance between the ends of the first pole piece 211 and the second pole piece 221 and the outer shell 10 can be designed to be smaller. On the one hand, the risk of short circuit between the electrode assembly 20 and the outer shell 10 is reduced, thereby improving the safety performance of the battery cell 100. On the other hand, the space utilization rate in the outer shell 10 is improved, and the energy density of the battery cell 100 is improved. At the same time, the diaphragm 23 with a continuous structure can complete the stacking of multiple electrode plate groups of different sizes in one stacking process, thereby facilitating the hot pressing of the electrode plates and diaphragms 23 in the same electrode plate group in one hot pressing, and completing the hot pressing of the composite assembly of multiple electrode plate groups of different sizes. Compared with the implementation method of hot pressing multiple electrode plate groups of different sizes separately and hot pressing them again when the multiple electrode plate groups are compositely assembled, the number of hot pressing times of the electrode assembly 20 is reduced. On the one hand, the number of hot pressing devices required for hot pressing the electrode assembly 20 is reduced, thereby reducing the investment in production costs; on the other hand, the number of hot pressing times of the diaphragm 23 located in the electrode plate group is reduced, thereby reducing the risk of a smaller thickness of part of the diaphragm 23 due to multiple hot pressings, thereby reducing the risk of reduced insulation withstand voltage performance of the battery cell 100 due to the smaller thickness of part of the diaphragm 23, and improving the reliability of the battery cell 100.

[0070] like Figure 5 and Figure 6 As shown, the one of the multiple first pole pieces 211 that is closest to the second pole piece group 22 is the first end pole piece 212, and the one of the multiple second pole pieces 221 that is closest to the first pole piece group 21 is the second end pole piece 222; the second end pole piece 222 has opposite polarity to the first end pole piece 212, and a first folding portion 231 is provided between the second end pole piece 222 and the first end pole piece 212.

[0071] The first end pole piece 212 refers to a pole piece at one end of the plurality of first pole pieces 211 in the first direction X. The first end pole piece 212 is closer to the second pole piece group 22 than other first pole pieces 211 .

[0072] The second end pole piece 222 refers to a pole piece at one end of the plurality of second pole pieces 221 in the first direction X. The second end pole piece 222 is closer to the first pole piece group 21 than other second pole pieces 221 .

[0073] In some embodiments, the second end electrode piece 222 is a positive electrode piece, and the second end electrode piece 222 includes a first area 222A overlapping with the positive electrode piece in the first electrode piece group 21 and a second area 222B not overlapping with the positive electrode piece in the first electrode piece group 21; or, the second end electrode piece 222 is a negative electrode piece, and the second end electrode piece 222 includes a first area 222A overlapping with the negative electrode piece in the first electrode piece group 21 and a second area 222B not overlapping with the negative electrode piece in the first electrode piece group 21, and a first folding portion 231 is provided between the second end electrode piece 222 and the first end electrode piece 212, and the first folding portion 231 does not cover the second area 222B 。

[0074] The first region 222A and the second region 222B are two interconnected regions of the second end pole piece 222. When viewed along the first direction X, the first region 222A overlaps with the first pole piece 211 of the first pole piece group 21 having the same polarity as the second end pole piece 222, and the second region 222B does not overlap with the first pole piece 211 of the first pole piece group 21 having the same polarity as the second end pole piece 222.

[0075] Exemplarily, the second region 222B may be disposed around the circumference of the first end pole piece 212 , or the second region 222B may be disposed on one side of the first end pole piece 212 in the second direction Y.

[0076] To facilitate the display of the range of the first area 222A and the second area 222B, please refer to Figure 5 In the figure, the range of the first area 222A and the second area 222B is marked by dotted lines. It should be noted that the dotted lines are only for the convenience of displaying the range of the first area 222A and the second area 222B, and do not represent any entity meaning.

[0077] The polarity of the second end electrode piece 222 is opposite to that of the first end electrode piece 212. For example, the second end electrode piece 222 may be a positive electrode piece, and the first end electrode piece 212 may be a negative electrode piece; or, the second end electrode piece 222 may be a negative electrode piece, and the first end electrode piece 212 may be a positive electrode piece.

[0078] like Figure 5As shown, a first folding portion 231 is provided between the second end pole piece 222 and the first end pole piece 212, and a first folding portion 231 closest to the second folding portion 232 among the plurality of first folding portions 231 is between the first end pole piece 212 and the second end pole piece 222 to separate the first end pole piece 212 and the second end pole piece 222. In this case, the first folding portion 231 provided between the first end pole piece 212 and the second end pole piece 222 can cover the surface of the first end pole piece 212 facing the second pole piece 221 along the first direction X to cover the first area 222A of the second end pole piece 222, thereby achieving insulation isolation between the first end pole piece 212 and the second end pole piece 222. In this way, the number of components between the first pole piece group 21 and the second pole piece group 22 can be reduced, the waste of the internal space of the housing 10 can be reduced, and the space in the housing 10 can be reasonably utilized.

[0079] Since the length of the first pole piece 211 in the second direction Y is smaller than the length of the second pole piece 221 in the second direction Y, the area of ​​the first pole piece 211 is smaller than the area of ​​the second pole piece 221, and the area of ​​the first folding portion 231 can be reduced accordingly, so that the first folding portion 231 can achieve insulation isolation between the first end pole piece 212 and the second end pole piece 222 without covering the second area 222B and only covering the first area 222A. In this case, the diaphragm 23 occupies space in the outer shell 10, which is convenient for arranging more active materials in the outer shell 10, so as to improve the energy density of the battery cell 100.

[0080] In one or more of the above optional embodiments, since the length of the second folding portion 232 in the second direction Y is greater than the length of the first folding portion 231, and then when the sizes of the second folding portion 232 and the first folding portion 231 in other directions are consistent, the volume of the second folding portion 232 is greater than the volume of the first folding portion 231, so that relative to a second folding portion 232 being provided between the second end pole piece 222 and the first end pole piece 212, a first folding portion 231 is provided between the second end pole piece 222 and the first end pole piece 212, thereby reducing the volume of the diaphragm 23, thereby reducing the space occupied by the diaphragm 23 in the outer shell 10, facilitating the provision of more active materials in the outer shell 10, and facilitating the improvement of the energy density of the battery cell 100.

[0081] like Figure 5 and Figure 6As shown, the first end pole piece 212 has a first end 212A and a second end 212B that are relatively arranged in the second direction Y, and the second pole piece 221 with the same polarity as the first end pole piece 212 in the second pole piece group 22 has a third end 221c and a fourth end 221d that are relatively arranged in the second direction Y; along the second direction Y, the fourth end 221d is flush with the second end 212B, and the third end 221c exceeds the first end 212A; the first connecting portion 233 wraps the first end.

[0082] The first end 212A and the second end 212B refer to two ends of the first end pole piece 212 that are oppositely disposed in the second direction Y.

[0083] The fourth end 221d and the third end 221c refer to two ends of the second pole piece 221 in the second pole piece group 22 that have the same polarity as the first end pole piece 212 and are arranged opposite to each other in the second direction Y.

[0084] In an embodiment where the second end pole piece 222 includes a first region 222A and a second region 222B, the first end 212A is closer to the second region 222B relative to the second end 212B, the third end 221c is closer to the second region 222B relative to the fourth end 221d, the second end 212B is farther away from the second region 222B relative to the first end 212A, and the fourth end 221d is farther away from the second region 222B relative to the third end 221c.

[0085] Exemplarily, when the first end pole piece 212 is a positive pole piece, the positive pole piece in the second pole piece group 22 extends beyond the first end along the second direction Y; when the first end pole piece 212 is a negative pole piece, the negative pole piece in the second pole piece group 22 extends beyond the first end along the second direction Y.

[0086] like Figure 6 As shown, the first connection portion 233 wraps the first end portion, which means that the first connection portion 233 and the first folding portion 231 located between the first electrode group 21 and the second electrode group 22 and the first folding portion 231 adjacent to the first folding portion 231 form a receiving space, and the first end of the first electrode 211 is received in the receiving space. Exemplarily, the first connection portion 233 may be attached to the first end of the first electrode 211, or there may be a gap between the first connection portion 233 and the first end of the first electrode 211. In this case, when the first end electrode 212 approaches the second region 222B along the second direction Y during hot pressing, the first connection portion 233 can limit the movement of the first end electrode 212, thereby reducing the risk of the first end electrode 212 approaching the second region 222B along the second direction Y, causing the electrode assembly 20 to be stacked misaligned. At the same time, the risk of internal short circuit of the electrode assembly 20 caused by the first end electrode 212 moving along the second direction Y and causing the first electrode 211 and the second electrode 221 to contact the part located in the second region 222B is reduced.

[0087] In one or more optional embodiments above, along the second direction Y, the length of the second electrode sheet group 22 is greater than the length of the first electrode sheet group 21, and along the second direction Y, the fourth end 221d is flush with the second end 212B, and the third end 221c exceeds the first end 212A, so that a part of the second end electrode sheet 222 exceeds the first end, and the first connecting portion 233 wraps the first end. Therefore, during hot pressing, the first connecting portion 233 can perform structural positioning on the first end electrode sheet 212, thereby reducing the risk of stacking misalignment of the electrode assembly 20 caused by the first end electrode sheet 212 moving along the second direction Y toward the area where the second end electrode sheet 222 exceeds the first end, and reducing the risk of internal short circuit of the electrode assembly 20 caused by the first end electrode sheet 212 moving along the second direction Y and the second end electrode sheet 222 contacting the area beyond the first end, thereby improving the production yield rate of the battery cell 100.

[0088] like Figure 7 and Figure 8 As shown, the one of the multiple first pole pieces 211 that is closest to the second pole piece group 22 is the first end pole piece 212, and the one of the multiple second pole pieces 221 that is closest to the first pole piece group 21 is the second end pole piece 222; the polarity of the second end pole piece 222 is opposite to that of the first end pole piece 212, and a second folding portion 232 is provided between the second end pole piece 222 and the first end pole piece 212.

[0089] like Figure 8 As shown, in the embodiment where the second end pole piece 222 includes the first region 222A and the second region 222B, a second folding portion 232 is provided between the second end pole piece 222 and the first end pole piece 212, and a second folding portion 232 closest to the first folding portion 231 among the plurality of second folding portions 232 is between the first end pole piece 212 and the second end pole piece 222, so as to separate the first end pole piece 212 and the second end pole piece 222. In this case, the second folding portion 232 provided between the first end pole piece 212 and the second end pole piece 222 can cover the surface of the second end pole piece 222 facing the second pole piece 221 along the first direction X, so as to cover the first region 222A and the second region 222B of the second end pole piece 222, so as to achieve insulation isolation between the first end pole piece 212 and the second end pole piece 222. Thus, the number of components between the first pole piece group 21 and the second pole piece group 22 can be reduced, the waste of the internal space of the housing 10 can be reduced, and the space in the housing 10 can be reasonably utilized.

[0090] Since the length of the second electrode 221 in the second direction Y is larger than the length of the first electrode 211 in the second direction Y, the area of ​​the second electrode 221 is larger than the area of ​​the first electrode 211, so that the area of ​​the second folded portion can cover the second region 222B. In this case, the housing 10 and the second region 222B of the second end electrode 222 can be insulated and isolated, and the first end electrode 212 and the second region 222B of the second end electrode 222 can be insulated and isolated, thereby reducing the risk of short circuit between the first electrode 211 and the second region 222B. Therefore, there is no need to remove the active material layer 24 of the second end electrode 222 on the side of the second region 222B facing the first electrode group 21.

[0091] In one or more of the above optional embodiments, the second folding portion 232 covers a partial area of ​​the second end pole piece 222 that extends beyond the first end pole piece 212 in the second direction Y, thereby reducing the risk of short circuit between the first end pole piece 212 and the partial area of ​​the second end pole piece 222 that extends beyond the first end pole piece 212 in the second direction Y, thereby improving the reliability of the battery cell 100.

[0092] like Figure 7 and Figure 8 As shown, the first end pole piece 212 has a first end 212A and a second end 212B that are relatively arranged in the second direction Y, and the second pole piece 221 with the same polarity as the first end pole piece 212 in the second pole piece group 22 has a third end 221c and a fourth end 221d that are relatively arranged in the second direction Y; along the second direction Y, the fourth end 221d is flush with the second end 212B, and the third end 221c exceeds the first end 212A; the third connecting portion 235 wraps the second end.

[0093] like Figure 8 As shown, the third connection portion 235 wraps the second end portion, which means that the third connection portion 235 and the second folding portion 232 located between the first electrode group 21 and the second electrode group 22 and the first folding portion 231 adjacent to the second folding portion 232 form a receiving space, and the second end of the first electrode 211 is received in the receiving space. Exemplarily, the third connection portion 235 may be in contact with the second end of the first electrode 211, or there may be a gap between the third connection portion 235 and the second end of the first electrode 211. In this case, when the first end electrode 212 is hot-pressed and moves away from the second region 222B along the second direction Y, the first connection portion 233 can limit the movement of the first end electrode 212, thereby reducing the risk of the first end electrode 212 approaching the second region 222B along the second direction Y, causing the electrode assembly 20 to be stacked misaligned.

[0094] In one or more of the above optional embodiments, the third connecting portion 235 wraps the second end of the first end pole piece 212 away from the second region 222B in the second direction Y to form an insulating isolation between the second end and the outer shell 10. In this case, the distance between the second end and the outer shell 10 can be smaller. On the one hand, the risk of short circuit between the second end and the outer shell 10 is reduced, thereby improving the safety performance of the battery cell 100. On the other hand, the space utilization inside the outer shell 10 is improved, thereby improving the energy density of the battery cell 100.

[0095] like Figure 5 and Figure 7 As shown, one of the multiple second pole pieces 221 closest to the first pole piece group 21 is the second end pole piece 222; the second end pole piece 222 is a positive pole piece, and the second end pole piece 222 includes a first area 222A overlapping with the positive pole piece in the first pole piece group 21 and a second area 222B not overlapping with the positive pole piece in the first pole piece group 21; or, the second end pole piece 222 is a negative pole piece, and the second end pole piece 222 includes a first area 222A overlapping with the negative pole piece in the first pole piece group 21 and a second area 222B not overlapping with the negative pole piece in the first pole piece group 21; along the first direction X, active material layers 24 are arranged on both sides of the first area 222A, and the active material layer 24 is arranged only on the side of the second area 222B away from the first pole piece group 21.

[0096] Figure 5 and Figure 7 The dotted line in may be a boundary line between the first region 222A and the second region 222B.

[0097] In some embodiments, the second end electrode piece 222 is a positive electrode piece, the first end electrode piece 212 can be a negative electrode piece, and a first folding portion 231 or a second folding portion 232 can be provided between the first end electrode piece 212 and the second end electrode piece 222 to facilitate the movement of metal ions between the first end electrode piece 212 and the second end electrode piece 222, thereby rationally utilizing the internal space of the outer shell 10 and facilitating the improvement of the energy density of the battery cell 100.

[0098] In some embodiments, the second end electrode piece 222 is a negative electrode piece, the first end electrode piece 212 can be a positive electrode piece, and a first folding portion 231 or a second folding portion 232 can be provided between the first end electrode piece 212 and the second end electrode piece 222 to facilitate the movement of metal ions between the first end electrode piece 212 and the second end electrode piece 222, thereby rationally utilizing the internal space of the outer shell 10 and facilitating the improvement of the energy density of the battery cell 100.

[0099] Along the first direction X, active material layers 24 are provided on both sides of the first region 222A, and active material layers 24 are provided only on the side of the second region 222B away from the first pole piece group 21. On the side of the second end pole piece 222 facing the first pole piece group 21, no active material layer 24 is provided in the second region 222B. On the side of the second end pole piece 222 away from the first pole piece group 21, the active material layer 24 of the first region 222A and the active material layer 24 of the second region 222B can be processed and formed simultaneously. For example, when the active material layer 24 is coated on the side of the second end electrode sheet 222 facing the first electrode sheet group 21, the active material layer 24 is coated only at the corresponding position of the first region 222A of the positive electrode collector; when the active material layer 24 is coated on the side of the second end electrode sheet 222 facing away from the first electrode sheet group 21, the active material layer 24 can be coated at the corresponding positions of the first region 222A and the second region 222B of the positive electrode collector at the same time, so that the active material layer 24 of the first region 222A and the active material layer 24 of the second region 222B are continuous.

[0100] In one or more of the above optional embodiments, the second region 222B of the second end electrode sheet 222 is provided with an active material layer 24 only on the side away from the first electrode sheet group 21, thereby reducing the active materials that do not exert their capacity and avoiding the space occupied by the active materials that do not exert their capacity, further reducing the energy density loss of the battery cell 100 in the first direction X, and at the same time reducing the use of active materials, reducing the production cost of the second end electrode sheet 222, and thereby reducing the production cost of the battery cell 100.

[0101] like Fig. 9 and Fig.10 As shown, the one of the multiple second pole pieces 221 that is closest to the first pole piece group 21 is the second end pole piece 222; the second end pole piece 222 is a positive pole piece, and the second end pole piece 222 includes a first area 222A overlapping with the positive pole piece in the first pole piece group 21 and a second area 222B that does not overlap with the positive pole piece in the first pole piece group 21; or, the second end pole piece 222 is a negative pole piece, and the second end pole piece 222 includes a first area 222A overlapping with the negative pole piece in the first pole piece group 21 and a second area 222B that does not overlap with the negative pole piece in the first pole piece group 21; along the first direction X, active material layers 24 are provided on both sides of the first area 222A, and active material layers 24 are provided on both sides of the second area 222B.

[0102] Along the first direction X, active material layers 24 are provided on both sides of the first region 222A, and active material layers 24 are provided on both sides of the second region 222B. During the preparation of the second end electrode piece 222, when the active material layer 24 is coated on the side of the second end electrode piece 222 facing the first end electrode piece 212, the active material layer 24 is simultaneously coated on the corresponding positions of the first region 222A and the second region 222B of the negative electrode collector; when the active material layer 24 is coated on the side of the second end electrode piece 222 away from the first end electrode piece 212, the active material layer 24 is simultaneously coated on the corresponding positions of the first region 222A and the second region 222B of the negative electrode collector, so that the second end electrode piece 222 has active material layers 24 on both sides in the first direction X.

[0103] In one or more of the above optional embodiments, active material layers 24 are provided on both sides of the second region 222B of the second end pole piece 222, so that when coating the side of the second end pole piece 222 facing the first pole piece group 21, the active material layer 24 can be simultaneously coated on the first region 222A and the second region 222B of the second end pole piece 222, thereby avoiding the problem of pole piece warping caused by different tensions on the two sides due to the active material layer 24 being provided on only one side of the second region 222B.

[0104] like Figure 5 , Figure 7 , Fig. 9 and Fig.10 As shown, the one farthest from the second pole piece group 22 among the multiple first pole pieces 211 is the third end pole piece 213, and the third end pole piece 213 is provided with an active material layer 24 only on the side facing the second pole piece group 22; the one farthest from the first pole piece group 21 among the multiple second pole pieces 221 is the fourth end pole piece 223, and the fourth end pole piece 223 is provided with an active material layer 24 only on the side facing the first pole piece group 21.

[0105] The third end pole piece 213 and the first end pole piece 212 are first pole pieces 211 at two ends of the plurality of first pole pieces 211 along the first direction X, and the third end pole piece 213 is the first pole piece 211 farthest from the second pole piece group 22 among the plurality of first pole pieces 211 .

[0106] In some embodiments, the third end electrode plate 213 is a positive electrode plate, and the positive electrode collector of the third end electrode plate 213 is only provided with a positive electrode active material layer 24 on the surface facing the second electrode plate group 22, and the positive electrode collector of the third end electrode plate 213 is not provided with a positive electrode active material layer 24 on the surface facing away from the second electrode plate group 22, and the surface has an empty foil area.

[0107] In some embodiments, the third end electrode sheet 213 is a negative electrode sheet, and the negative electrode collector of the third end electrode sheet 213 is only provided with a negative electrode active material layer 24 on the surface facing the second electrode sheet group 22, and the negative electrode collector of the third end electrode sheet 213 is not provided with a negative electrode active material layer 24 on the surface facing away from the second electrode sheet group 22, and the surface has an empty foil area.

[0108] The fourth end pole piece 223 and the second end pole piece 222 are the second pole pieces 221 at two ends of the plurality of second pole pieces 221 along the first direction X. The fourth end pole piece 223 is the second pole piece 221 farthest from the first pole piece group 21 among the plurality of second pole pieces 221 .

[0109] In some embodiments, the fourth end electrode plate 223 is a positive electrode plate, and the positive electrode collector of the fourth end electrode plate 223 is only provided with a positive electrode active material layer 24 on the surface facing the second electrode plate group 22, and the positive electrode collector of the fourth end electrode plate 223 is not provided with a positive electrode active material layer 24 on the surface facing away from the second electrode plate group 22, and the surface has an empty foil area.

[0110] In some embodiments, the fourth end electrode sheet 223 is a negative electrode sheet, and the negative electrode collector of the fourth end electrode sheet 223 is provided with a negative electrode active material layer 24 only on the surface facing the second electrode sheet group 22, and the negative electrode collector of the fourth end electrode sheet 223 is not provided with a negative electrode active material layer 24 on the surface facing away from the second electrode sheet group 22, and the surface has an empty foil area.

[0111] In one or more optional embodiments above, the third end pole piece 213 is provided with an active material layer 24 only on the side facing the second pole piece group 22, which can reasonably utilize the internal space of the shell 10, and is convenient for improving the energy density of the battery cell 100; at the same time, the active material layer 24 is not provided on the side of the third end pole piece 213 away from the second pole piece group 22, so as to facilitate bonding with other components (such as insulating parts, shell 10, etc.). The fourth end pole piece 223 is provided with an active material layer 24 only on the side facing the first pole piece group 21, which can reasonably utilize the internal space of the shell 10, and is convenient for improving the energy density of the battery cell 100; at the same time, the active material layer 24 is not provided on the side of the fourth end pole piece 223 away from the first pole piece group 21, so as to facilitate bonding with other components (such as insulating parts, shell 10, etc.).

[0112] like Figure 1 and Figure 2As shown, the housing 10 includes a first wall 11 and a second wall 12 arranged opposite to each other along a first direction X, the first wall 11 includes a first sub-wall 111, a second sub-wall 112 and a first connecting wall 113, the second sub-wall 112 protrudes from the first wall 11 in a direction away from the second wall 12, and the first connecting wall 113 connects the first sub-wall 111 and the second sub-wall 112; the second pole piece group 22 is arranged between the first sub-wall 111 and the second wall 12, and the first pole piece group 21 is arranged between the second sub-wall 112 and the second pole piece group 22.

[0113] The first wall 11 and the second wall 12 are spaced apart in the first direction X so as to form a space for accommodating the electrode assembly 20 between the first wall 11 and the second wall 12 .

[0114] In some embodiments, the housing 10 may include a cover and a shell, the cover may be the first wall 11 , or one wall of the shell may be the first wall 11 .

[0115] In some embodiments, the first sub-wall 111 , the first connecting wall 113 and the second sub-wall 112 may be distributed in sequence along the second direction Y, and the first sub-wall 111 , the first connecting wall 113 and the second sub-wall 112 may be integrally formed, for example, the first wall 111 may be stamped.

[0116] The second sub-wall 112 is farther away from the second wall 12 than the first sub-wall 111 , and the second sub-wall 112 may be parallel to the first sub-wall 111 .

[0117] In some embodiments, the first pole piece group 21 and the second pole piece group 22 form a first step 20A at at least one end in the second direction Y, the second sub-wall 112 and the first sub-wall 111 are spaced apart in the second direction Y, and the first connecting wall 113 connects the second sub-wall 112 and the first sub-wall 111 to form a second step 10A corresponding to the first step 20A.

[0118] Along the second direction Y, the length of the second pole piece group 22 is greater than the length of the second sub-wall 112 , and a portion of the second pole piece group 22 is located between the first sub-wall 111 and the second wall 12 .

[0119] Along the second direction Y, the length of the first pole piece group 21 is smaller than the length of the second sub-wall 112 , and the first pole piece group 21 is located between the second sub-wall 112 and the second pole piece group 22 .

[0120] In one or more of the above optional embodiments, the second sub-wall 112 protrudes from the first sub-wall 111 in a direction away from the second wall 12, and the first connecting wall 113 connects the first sub-wall 111 and the second sub-wall 112 to form a step on the surface of the first wall 11 away from the second wall 12, and the step is sufficient for placing components, so that the battery cell 100 can occupy other space in the battery compartment of the electrical equipment except for the space where the components are located, thereby improving the space utilization of the battery compartment and further improving the compactness of the internal structure of the electrical equipment; the second electrode plate group 22 is arranged between the first sub-wall 111 and the second wall 12, and the first electrode plate group 21 is arranged between the second sub-wall 112 and the second electrode plate group 22, so that the electrode assembly 20 can fully occupy the internal space of the outer shell 10, so that when the volume of the battery compartment is constant, the energy density of the battery cell 100 is higher, which is beneficial to improving the endurance of the electrical equipment.

[0121] According to some embodiments of the present application, the present application further provides an electrical device, which includes a device body and a battery cell 100 provided according to any of the above embodiments. The device body has a battery compartment, the battery cell 100 is accommodated in the battery compartment, and the second step 10A is used to avoid components arranged in the battery compartment.

[0122] The electric device may be any terminal or system using the battery cell 100 as described above.

[0123] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0124] The above embodiments are only used to illustrate the technical solution of the present application and are not used to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: It comprises a housing and an electrode assembly, wherein the electrode assembly is accommodated in the housing; The electrode assembly comprises: A first pole piece group, comprising a plurality of first pole pieces stacked along a first direction; A second pole piece group, wherein the first pole piece group and the second pole piece group are stacked along the first direction, the second pole piece group comprises a plurality of second pole pieces stacked along the first direction, along the second direction, the length of the second pole piece group is greater than the length of the first pole piece group, and the second direction is perpendicular to the first direction; A diaphragm, comprising a plurality of first folded portions and a plurality of second folded portions, wherein along the second direction, the length of the second folded portions is greater than that of the first folded portions; The diaphragm further comprises at least one first connection portion, at least one second connection portion and a third connection portion; A plurality of first folding portions are arranged at intervals along the first direction, a first pole piece is arranged between two adjacent first folding portions, and the first connecting portion connects two adjacent first folding portions; a plurality of second folding portions are arranged at intervals along the first direction, a second pole piece is arranged between two adjacent second folding portions, and the second connecting portion connects two adjacent second folding portions; the third connecting portion connects adjacent first folding portions and second folding portions.

2. The battery cell according to claim 1, characterized in that: The one of the plurality of first pole pieces that is closest to the second pole piece group is a first end pole piece, and the one of the plurality of second pole pieces that is closest to the first pole piece group is a second end pole piece; The second end pole piece has a polarity opposite to that of the first end pole piece, and a first folded portion is disposed between the second end pole piece and the first end pole piece.

3. The battery cell according to claim 2, characterized in that: The first end pole piece has a first end and a second end oppositely disposed in the second direction, and a second pole piece in the second pole piece group having the same polarity as the first end pole piece has a third end and a fourth end oppositely disposed in the second direction; Along the second direction, the fourth end is flush with the second end, and the third end exceeds the first end; The first connecting portion wraps the first end.

4. The battery cell according to claim 1, characterized in that: The one of the plurality of first pole pieces that is closest to the second pole piece group is a first end pole piece, and the one of the plurality of second pole pieces that is closest to the first pole piece group is a second end pole piece; The second end pole piece has a polarity opposite to that of the first end pole piece, and a second folded portion is disposed between the second end pole piece and the first end pole piece.

5. The battery cell according to claim 4, characterized in that: The first end pole piece has a first end and a second end oppositely disposed in the second direction, and a second pole piece in the second pole piece group having the same polarity as the first end pole piece has a third end and a fourth end oppositely disposed in the second direction; Along the second direction, the fourth end is flush with the second end, and the third end exceeds the first end; The third connecting portion wraps the second end.

6. The battery cell according to claim 1, characterized in that: The one of the plurality of second pole pieces closest to the first pole piece group is a second end pole piece; The second end electrode piece is a positive electrode piece, and the second end electrode piece includes a first area overlapping with the positive electrode piece in the first electrode piece group and a second area not overlapping with the positive electrode piece in the first electrode piece group; or, the second end electrode piece is a negative electrode piece, and the second end electrode piece includes a first area overlapping with the negative electrode piece in the first electrode piece group and a second area not overlapping with the negative electrode piece in the first electrode piece group; Along the first direction, active material layers are disposed on both sides of the first region, and active material layers are disposed only on one side of the second region away from the first pole piece group.

7. The battery cell according to claim 1, characterized in that: The one of the plurality of second pole pieces closest to the first pole piece group is a second end pole piece; The second end electrode piece is a positive electrode piece, and the second end electrode piece includes a first area overlapping with the positive electrode piece in the first electrode piece group and a second area not overlapping with the positive electrode piece in the first electrode piece group; or, the second end electrode piece is a negative electrode piece, and the second end electrode piece includes a first area overlapping with the negative electrode piece in the first electrode piece group and a second area not overlapping with the negative electrode piece in the first electrode piece; Along the first direction, active material layers are disposed on both sides of the first region, and active material layers are disposed on both sides of the second region.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The one of the plurality of first pole pieces that is farthest from the second pole piece group is a third end pole piece, and the third end pole piece is provided with an active material layer only on a side facing the second pole piece group; The one of the plurality of second pole pieces that is farthest from the first pole piece group is a fourth end pole piece, and the fourth end pole piece is provided with an active material layer only on a side facing the first pole piece group.

9. The battery cell according to any one of claims 1 to 7, characterized in that: The housing comprises a first wall and a second wall arranged opposite to each other along the first direction, the first wall comprises a first sub-wall, a second sub-wall and a first connecting wall, the second sub-wall protrudes from the first wall in a direction away from the second wall, and the first connecting wall connects the first sub-wall and the second sub-wall; The second pole piece group is arranged between the first sub-wall and the second wall, and the first pole piece group is arranged between the second sub-wall and the second pole piece group.

10. An electrical device, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 9, wherein the battery cell is used to provide electrical energy.

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