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. The electrode assembly is accommodated in the shell; the electrode assembly comprises a first pole piece group, a second pole piece group, a first diaphragm and a plurality of second diaphragms. The first pole piece group comprises a plurality of first pole pieces which are stacked in the first direction; the first pole piece group and the second pole piece group are laminated along the first direction, the second pole piece group comprises a plurality of second pole pieces laminated along the first direction, and the length of the second pole piece group is greater than that of the first pole piece group along the second direction; the first diaphragm comprises a plurality of folding parts and at least one connecting part, the plurality of folding parts are arranged at intervals along a first direction, a first pole piece is arranged between two adjacent folding parts, and the connecting part is connected with the two adjacent folding parts; the plurality of second diaphragms are arranged at intervals along the first direction and are not connected, and one second pole piece is arranged between every two adjacent second diaphragms. According to the technical scheme provided by the invention, the safety performance of the battery cell can be improved.

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 plates in the electrode group need to be separated by a diaphragm; for stacked electrode groups, especially larger electrode groups, the area of ​​the electrode is large, and the continuous structure of the diaphragm and the electrode are poorly bonded, which can easily affect the safety performance of the battery cell. Therefore, how to improve the safety performance of the battery cell is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present application provides a battery cell and electrical equipment, which can improve the safety performance of the battery cell.

[0005] This application is achieved through the following technical solutions:

[0006] In the first aspect, the present application provides a battery cell, which includes a housing and an electrode assembly. The electrode assembly is accommodated in the housing; the electrode assembly includes a first electrode group, a second electrode group, a first diaphragm and a plurality of second diaphragms. 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 first diaphragm includes a plurality of folding portions and at least one connecting portion, the plurality of folding portions are spaced apart along the first direction, a first electrode sheet is arranged between two adjacent folding portions, and the connecting portion connects two adjacent folding portions; the plurality of second diaphragms are spaced apart and not connected along the first direction, and a second electrode sheet is arranged between two adjacent second diaphragms.

[0007] 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 length of the first electrode group in the second direction is small, the area of ​​the first electrode is small, and when the first diaphragm of the continuous structure is stacked and compounded with multiple first electrode sheets, the first diaphragm is not easy to wrinkle, and the first diaphragm and the first electrode sheet have a good bonding effect; at the same time, when the first diaphragm of the continuous structure is stacked and compounded with multiple first electrode sheets, the first diaphragm can wrap the end of the first electrode sheet, forming an insulating isolation between the end of the first electrode sheet and the outer shell, so that the distance between the end of the first electrode sheet and the outer shell can be designed to be smaller. On the one hand, the risk of short circuit between the first electrode sheet 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. The length of the second electrode plate group in the second direction is relatively large, and the area of ​​the second electrode plate is relatively large. If multiple second electrode plates are compounded with a diaphragm with a continuous structure, it is easy to cause the diaphragm to wrinkle, affecting the fitting effect between the diaphragm and the second electrode plate. Therefore, in the present application, the number of second diaphragms is multiple, and multiple second diaphragms and multiple second electrode plates are stacked so that the second diaphragms and the second electrode plates can fit well, thereby improving the connection reliability between the second diaphragms and the second electrode plates, and thereby improving the safety performance of the battery cell.

[0008] In one or more of the above optional embodiments, the number of first pole pieces is less than the number of second pole pieces.

[0009] In the above scheme, the first diaphragm is a continuous structure, the number of first pole pieces is less than the number of second pole pieces, and the composite assembly time of multiple first pole pieces and the first diaphragm is short, thereby improving the assembly efficiency of the first pole piece group and the first diaphragm.

[0010] In one or more of the above optional embodiments, the connecting portion is located on at least one side of the first pole piece group along the second direction.

[0011] In the above scheme, the connecting portion can be located on one side of the first pole piece group along the second direction, or on both sides of the first pole piece group along the second direction, so as to reduce the risk of short circuit between the first pole piece and the shell and improve the safety performance of the battery cell.

[0012] In one or more of the above optional embodiments, one of the multiple first pole pieces that is closest to the second pole piece group is the first end pole piece, and one of the multiple second pole pieces that is closest to the first pole piece group is the second end pole piece. The polarity of the second end pole piece is opposite to that of the first end pole piece, and a folding portion is provided between the second end pole piece and the first end pole piece.

[0013] In the above scheme, relative to the scheme in which the polarity of the second end electrode piece is the same as the polarity of the first end electrode piece, the polarity of the second end electrode piece is opposite to the polarity of the first end electrode piece, and the second end electrode piece is separated from the first end electrode piece by a folded part, which can reduce redundant structural parts such as current collectors and adhesive layers, reduce space waste, and reasonably utilize the space in the outer shell, making it convenient to arrange more active materials in the outer shell, thereby facilitating the improvement of the energy density of the battery cell.

[0014] In one or more of the above optional embodiments, the one of the multiple second electrode sheets closest to the first electrode sheet group is the second end electrode sheet, the second end electrode sheet is the positive electrode sheet, and the second end electrode sheet includes a first area overlapping with the positive electrode sheet of the first electrode sheet group and a second area not overlapping with the positive electrode sheet of the first electrode sheet group; along the first direction, positive electrode active material layers are arranged on both sides of the first area, and the positive electrode active material layer is arranged only on the side of the second area away from the first electrode sheet group.

[0015] In the above scheme, the second end electrode sheet is a positive electrode sheet, and positive electrode active material layers are arranged on both sides of the first area of ​​the second end electrode sheet overlapping with the positive electrode sheet of the first electrode sheet group, so as to facilitate the movement of metal ions between the second electrode sheet and the first electrode sheet, which is beneficial for the battery cell to have a higher energy density; the second area is only provided with a positive electrode active material layer on the side away from the first electrode sheet group, which reduces the active materials that do not exert their capacity and avoids the space occupied by the active materials that do not exert their capacity, further reduces the energy density loss of the battery cell in the first direction, and at the same time reduces the use of active materials, reduces the production cost of the second end electrode sheet, and thus reduces the production cost of the battery cell.

[0016] In one or more of the above optional embodiments, the one of the multiple second electrode sheets closest to the first electrode sheet group is the second end electrode sheet, the second end electrode sheet is the positive electrode sheet, and the second end electrode sheet includes a first area overlapping with the positive electrode sheet of the first electrode sheet group and a second area not overlapping with the positive electrode sheet of the first electrode sheet group; along the first direction, positive electrode active material layers are arranged on both sides of the first area, and positive electrode active material layers are arranged on both sides of the second area.

[0017] In the above scheme, the second end electrode piece is a positive electrode piece, and positive electrode active material layers are arranged on both sides of the second end electrode piece in the thickness direction to facilitate the movement of metal ions between the second electrode piece and the first electrode piece, which is beneficial for the battery cell to have a higher energy density; at the same time, when the active material is coated on the side of the second end electrode piece facing the first electrode piece group, the positive electrode active material layer can be coated on the first area and the second area at the same time. Compared with the case of coating only the first area, there is no need to avoid the second area during coating, which facilitates the coating process of the second end electrode piece.

[0018] In one or more of the above optional embodiments, the one of the multiple second pole pieces closest to the first pole piece group is the second end pole piece, the second end pole piece is the negative pole piece, and the second end pole piece includes a first area overlapping with the first pole piece group and a second area not overlapping with the first pole piece group; along the first direction, negative electrode active material layers are arranged on both sides of the first area, and the negative electrode active material layer is arranged only on the side of the second area away from the first pole piece group.

[0019] In the above scheme, the second end electrode sheet is a negative electrode sheet, and negative electrode active material layers are arranged on both sides of the first region of the second end electrode sheet overlapping with the first electrode sheet group, so as to facilitate the movement of metal ions between the second electrode sheet and the first electrode sheet, which is beneficial for the battery cell to have a higher energy density; the second region is only provided with a negative electrode active material layer on the side away from the first electrode sheet group, which reduces the active materials that do not exert their capacity and avoids the space occupied by the active materials that do not exert their capacity, further reduces the energy density loss of the battery cell in the first direction, and at the same time reduces the use of active materials, reduces the production cost of the second end electrode sheet, and thus reduces the production cost of the battery cell.

[0020] In one or more of the above optional embodiments, the one of the multiple second pole pieces closest to the first pole piece group is the second end pole piece, the second end pole piece is the negative pole piece, and the second end pole piece includes a first area overlapping with the first pole piece group and a second area not overlapping with the first pole piece group; along the first direction, negative electrode active material layers are arranged on both sides of the first area, and negative electrode active material layers are arranged on both sides of the second area.

[0021] In the above scheme, the second end electrode sheet is a negative electrode sheet, and negative electrode active material layers are arranged on both sides of the negative electrode sheet in the thickness direction to facilitate the movement of metal ions between the second electrode sheet and the first electrode sheet, which is beneficial for the battery cell to have a higher energy density; at the same time, when the active material is coated on the side of the second end electrode sheet facing the first electrode sheet group, the negative electrode active material layer can be coated on the first area and the second area at the same time. Compared with the case of coating only the first area, there is no need to avoid the second area during coating, which facilitates the coating process of the second end electrode sheet.

[0022] In one or more of the above optional embodiments, the one of the multiple first pole pieces that is farthest from the second pole piece group is the third end pole piece, the third end pole piece is a positive pole piece, and the third end pole piece is provided with a positive electrode 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 the fourth end pole piece, the fourth end pole piece is a positive pole piece, and the fourth end pole piece is provided with a positive electrode active material layer only on the side facing the first pole piece group.

[0023] In the above scheme, the third end electrode piece is a positive electrode piece, and the third end electrode piece is provided with a positive electrode active material layer only on the side facing the second electrode piece group, which can reasonably utilize the internal space of the shell, and is convenient for improving the energy density of the battery cell; at the same time, the third end electrode piece is not provided with a positive electrode active material layer on the side away from the second electrode piece group, so as to facilitate bonding with other components (such as insulating parts, shells, etc.). The fourth end electrode piece is a positive electrode piece, and the fourth end electrode piece is provided with a positive electrode active material layer only on the side facing the first electrode piece group, which can reasonably utilize the internal space of the shell, and is convenient for improving the energy density of the battery cell; at the same time, the fourth end electrode piece is not provided with a positive electrode active material layer on the side away from the first electrode piece group, so as to facilitate bonding with other components (such as insulating parts, shells, etc.).

[0024] In one or more of the above optional embodiments, the shell includes a first wall and a second wall arranged opposite to each other along a 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 sub-wall along 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.

[0025] In the above solution, the second sub-wall protrudes from the first sub-wall, the first connecting wall connects the first sub-wall and the second sub-wall, and the shell is stepped so that the battery cell can fit into a limited assembly space and increase the adaptability of the battery cell.

[0026] In a second aspect, the present application also provides an electrical device, which includes a battery cell provided according to any of the above embodiments.

[0027] 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

[0028] 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.

[0029] Figure 1 A three-dimensional diagram of a battery cell provided in some embodiments of the present application;

[0030] Figure 2 A cross-sectional view of a battery cell provided in some embodiments of the present application;

[0031] Figure 3 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0032] Figure 4 for Figure 3 A local enlarged view of point A;

[0033] Figure 5 A schematic diagram of the structure of an electrode assembly provided in some other embodiments of the present application;

[0034] Figure 6 for Figure 5 A partial enlarged view of point B;

[0035] Figure 7 A schematic diagram of the structure of an electrode assembly provided in some other embodiments of the present application;

[0036] Figure 8 for Figure 7 A partial enlarged view of point C;

[0037] Fig. 9 A schematic diagram of the structure of an electrode assembly provided in some further embodiments of the present application;

[0038] Fig.10 for Fig. 9 A partial enlarged view of point D;

[0039] Fig.11 for Figure 2 A partial enlarged view of point E.

[0040] Icon: 100-battery cell; 1-housing; 11-first wall; 111-first sub-wall; 112-second sub-wall; 113-first connecting wall; 12-second wall; 13-third wall; 14-fourth wall; 15-second step; 2-electrode assembly; 21-first pole piece group; 211-first pole piece; 212-first end pole piece; 213-third end pole piece; 22-second pole piece group; 221-second pole piece; 222-second end pole piece; 222a-first region; 222b-second region; 223-fourth end Pole piece; 23-first diaphragm; 231-folding part; 232-connecting part; 24-second diaphragm; 25-first step; 26-positive electrode piece; 26a-first positive electrode piece; 26b-second positive electrode piece; 261-positive electrode active material layer; 262-positive electrode collector; 27-negative electrode piece; 27a-first negative electrode piece; 27b-second negative electrode piece; 271-negative electrode active material layer; 272-negative electrode collector; 28-positive electrode ear; 29-negative electrode ear; X-first direction; Y-second direction; Z-third direction. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0042] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning 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.

[0043] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations 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. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0044] 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.

[0045] 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.

[0046] 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).

[0047] The battery cell includes a shell, an electrode assembly and an electrolyte. The shell is used to hold the electrode assembly and the electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The separator can be made of 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 arranged 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 the 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, and the length of the first pole piece group is less than the length of the second pole piece group. The electrode assembly is a laminated structure. In order to improve the safety performance of the battery cell and reduce the risk of short circuit between the pole piece and the shell, the diaphragm is a continuous structure, the diaphragm is folded in a Z shape, and the diaphragm can wrap the end of the pole piece to form an insulating isolation between the end of the pole piece and the shell. However, due to the large length of the second pole piece group and the large area of ​​the second pole piece of the second pole piece group, the continuous diaphragm is easy to wrinkle when compounded with the second pole piece, resulting in poor lamination between the diaphragm and the second pole piece, which is easy to cause short circuit between the positive and negative poles, making the safety performance of the battery cell poor.

[0049] In order to solve the problem that the diaphragm and the electrode sheet have poor bonding effect and cause the positive and negative electrodes to short-circuit, the present application provides a battery cell, including a shell and an electrode assembly, and the electrode assembly is accommodated in the shell. The electrode assembly includes a first electrode sheet group, a second electrode sheet group, a first diaphragm and a plurality of second diaphragms. The first electrode sheet group includes a plurality of first electrode sheets stacked along a first direction; the first electrode sheet group and the second electrode sheet group are stacked along the first direction, and the second electrode sheet group includes a plurality of second electrode sheets stacked along the first direction. Along the second direction, the length of the second electrode sheet group is greater than the length of the first electrode sheet group, and the second direction is perpendicular to the first direction; the first diaphragm includes a plurality of folding parts and at least one connecting part, and the plurality of folding parts are arranged at intervals along the first direction, and a first electrode sheet is arranged between two adjacent folding parts, and the connecting part connects two adjacent folding parts; the plurality of second diaphragms are arranged at intervals along the first direction, and a second electrode sheet is arranged between two adjacent second diaphragms.

[0050] In such a battery cell, the length of the first electrode group in the second direction is different from the length of the second electrode group in the second direction. In the electrical equipment constituted by the battery cell, after the battery cell is set in the battery compartment of the electrical equipment, other components can be set in the second direction so that the shape of the battery cell can adapt to the shape of the battery compartment of the electrical equipment. The length of the first electrode group in the second direction is small, the area of ​​the first electrode is small, and when the first diaphragm of the continuous structure is stacked and compounded with multiple first electrode sheets, the first diaphragm is not easy to wrinkle, and the first diaphragm and the first electrode sheet have a good bonding effect; at the same time, when the first diaphragm of the continuous structure is stacked and compounded with multiple first electrode sheets, the first diaphragm can wrap the end of the first electrode sheet, forming an insulating isolation between the end of the first electrode sheet and the outer shell, so that the distance between the end of the first electrode sheet and the outer shell can be designed to be small. On the one hand, the risk of short circuit between the first electrode sheet 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. The second electrode group has a larger length in the second direction, and the area of ​​the second electrode is larger. Multiple second diaphragms and multiple second electrode sheets are stacked so that the second diaphragms and the second electrode sheets fit well, thereby improving the connection reliability between the second diaphragms and the second electrode sheets, and thereby improving the safety performance 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] Please refer to Figures 1 to 4 , Figure 1 A three-dimensional diagram of a battery cell provided in some embodiments of the present application, Figure 2 A cross-sectional view of a battery cell provided in some embodiments of the present application, Figure 3 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application, Figure 4 for Figure 3The embodiment of the present application provides a battery cell 100, which includes a housing 1 and an electrode assembly 2. The electrode assembly 2 is accommodated in the housing 1; the electrode assembly 2 includes a first electrode sheet group 21, a second electrode sheet group 22, a first diaphragm 23 and a plurality of second diaphragms 24. The first electrode group 21 includes a plurality of first electrode sheets 211 stacked along the first direction X; the first electrode group 21 and the second electrode group 22 are stacked along the first direction X, the second electrode group 22 includes a plurality of second electrode sheets 221 stacked along the first direction X, along the second direction Y, the length of the second electrode group 22 is greater than the length of the first electrode group 21, and the second direction Y is perpendicular to the first direction X; the first diaphragm 23 includes a plurality of folding portions 231 and at least one connecting portion 232, the plurality of folding portions 231 are arranged at intervals along the first direction X, a first electrode sheet 211 is arranged between two adjacent folding portions 231, and the connecting portion 232 connects two adjacent folding portions 231; the plurality of second diaphragms 24 are arranged at intervals along the first direction X and are not connected, and a second electrode sheet 221 is arranged between two adjacent second diaphragms 24.

[0055] In some embodiments, the housing 1 is used to provide a storage space to accommodate the electrode assembly 2. The housing 1 may be a hard shell, for example, the housing 1 may be a stainless steel shell or a hard aluminum shell, forming a steel shell battery or an aluminum shell battery. The housing 1 may also be formed of a softer material, for example, the housing 1 may be an aluminum plastic film or a steel plastic film, forming a soft-pack battery cell.

[0056] In some embodiments, the electrode assembly 2 is a laminated structure, and the plurality of first pole pieces 211 and the plurality of second pole pieces 221 are stacked along the thickness direction of the electrode assembly 2. The first direction X may be parallel to the thickness direction of the electrode assembly 2, and the second direction Y may be perpendicular to the thickness direction of the electrode assembly 2. 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.

[0057] The second electrode sheet group 22 is taken as a whole, and the length of the second electrode sheet group 22 in the second direction Y may be the length of the negative electrode sheet (such as the second negative electrode sheet) in the second electrode sheet group 22 in the second direction Y. The first electrode sheet group 21 is taken as a whole, and the length of the first electrode sheet group 21 in the second direction Y may be the length of the negative electrode sheet (such as the first negative electrode sheet) in the first electrode sheet group in the second direction Y. “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” may mean that the length of the negative electrode sheet (such as the second negative electrode sheet) in the second electrode sheet group 22 in the second direction Y is greater than the length of the negative electrode sheet (such as the first negative electrode sheet) in the first electrode sheet group in the second direction Y.

[0058] Optionally, the length of the positive electrode sheet (such as the second positive electrode sheet) in the second electrode sheet group 22 in the second direction Y may also be greater than the length of the negative electrode sheet (such as the first negative electrode sheet) in the first electrode sheet group in the second direction Y.

[0059] Please refer to Figure 2 The plurality of first pole pieces 211 include a first positive pole piece 26a and a first negative pole piece 27a, and the first positive pole piece 26a and the first negative pole piece 27a are arranged alternately. The plurality of second pole pieces 221 include a second positive pole piece 26b and a second negative pole piece 27b, and the second positive pole piece 26b and the second negative pole piece 27b are arranged alternately.

[0060] In the embodiment of the present application, the positive electrode plate includes a positive electrode current collector and a positive electrode active material layer, at least one side of the positive electrode current collector is provided with a positive electrode active material layer, the material of the positive electrode current collector may include aluminum, and the positive electrode active material 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, at least one side of the negative electrode current collector is provided with a negative electrode active material layer, the material of the negative electrode current collector may include copper, and the negative electrode active material may be carbon or silicon, etc.

[0061] The first diaphragm 23 is a continuous structure. Along the length direction of the first diaphragm 23 , the folded portions 231 and the connecting portions 232 are alternately arranged. The folded portions 231 may be parallel to the first pole piece 211 . A plurality of folded portions 231 are spaced apart along the first direction X.

[0062] In some embodiments, when the number of connecting portions 232 is one, the number of folding portions 231 is two, and the two folding portions 231 are connected by the connecting portion 232; or, the number of connecting portions 232 and the number of folding portions 231 are multiple, the number of folding portions 231 is greater than the number of connecting portions 232, and two adjacent folding portions 231 are connected by the connecting portion 232.

[0063] In some embodiments, the first separator 23 may be in a U-shape, for example, the number of the connecting portion 232 is one, the number of the folding portions 231 is two, and in this case, a first electrode sheet 211 is disposed between the two folding portions 231. Alternatively, the first separator 23 may be in a Z-shape, for example, the number of the connecting portion 232 and the number of the folding portions 231 are multiple, and a first electrode sheet 211 is disposed between two adjacent folding portions 231. Since the first separator 23 is a continuous structure, when the first separator 23 is compounded with multiple first electrode sheets 211, the first separator 23 may wrap the end of the first electrode sheet 211. For example, a connecting portion 232 may be disposed between the first end of the negative electrode sheet and the housing 1 to form an insulation isolation between the first end and the housing 1. In this case, the distance between the first end and the housing 1 may be small. On the one hand, the risk of short circuit between the negative electrode sheet and the housing 1 is reduced, thereby improving the safety performance of the battery cell 100. On the other hand, the space utilization rate in the housing 1 is improved, thereby improving the energy density of the battery cell 100. The first end of the negative electrode sheet may be an end of the negative electrode sheet in the second direction Y, and the first end of the negative electrode sheet may also be an end of the negative electrode sheet in the third direction Z, and the third direction Z, the second direction Y and the first direction X are perpendicular to each other. It should be noted that the first diaphragm 23 wraps the end of the first electrode sheet 211, which means that a receiving space is formed between the connecting portion 232 of the first diaphragm 23 and two adjacent folding portions 231, and the end of the first electrode sheet 211 is received in the receiving space, and the connecting portion 232 may fit the end, or there may be a gap between the connecting portion 232 and the end.

[0064] At the same time, the first diaphragm 23 may also separate the first electrode sheet 211 from the second electrode sheet 221 . For example, one of the plurality of folded portions 231 may be disposed between the first electrode sheet 211 and the second electrode sheet 221 .

[0065] In some embodiments, when multiple second diaphragms 24 are assembled with multiple second pole pieces 221, the second diaphragms 24 are parallel to the second pole pieces 221, and the multiple second diaphragms 24 are spaced apart and not connected along the first direction X, so that a second pole piece 221 is provided between two adjacent second diaphragms 24, thereby separating the two adjacent second pole pieces 221.

[0066] In some embodiments, the first diaphragm 23 and the second diaphragm 24 may be made of polypropylene or polyethylene.

[0067] According to the battery cell 100 of the embodiment of the present application, the length of the first electrode group 21 in the second direction Y is different from the length of the second electrode group 22 in the second direction Y. In the electrical device formed by the battery cell 100, after the battery cell 100 is arranged in the battery compartment of the electrical device, other components can be arranged 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 length of the first electrode group 21 in the second direction Y is small, the area of ​​the first electrode 211 is small, and when the first diaphragm 23 with a continuous structure is stacked and compounded with multiple first electrode sheets 211, the first diaphragm 23 is not easy to wrinkle, and the first diaphragm 23 and the first electrode sheet 211 have a good bonding effect; at the same time, when the first diaphragm 23 with a continuous structure is stacked and compounded with multiple first electrode sheets 211, the first diaphragm 23 can wrap the end of the first electrode sheet 211, and a connecting portion 232 is provided between the end of the first electrode sheet and the outer shell 1 to form an insulating isolation between the end of the first electrode sheet 211 and the outer shell 1, so that the distance between the end of the first electrode sheet 211 and the outer shell 1 can be designed to be smaller. On the one hand, the risk of short circuit between the first electrode sheet and the outer shell 1 is reduced, thereby improving the safety performance of the battery cell 100, and on the other hand, the space utilization rate in the outer shell 1 is improved, thereby improving the energy density of the battery cell 100. The length of the second electrode plate group 22 in the second direction Y is relatively large, and the area of ​​the second electrode plate 221 is relatively large. If multiple second electrode plates 221 are compounded with a diaphragm of a continuous structure, it is easy to cause the diaphragm to wrinkle, affecting the fitting effect between the diaphragm and the second electrode plate 221. Therefore, in the present application, the number of second diaphragms 24 is multiple, and multiple second diaphragms 24 and multiple second electrode plates 221 are stacked so that the second diaphragms 24 and the second electrode plates 221 can fit well, thereby improving the connection reliability between the second diaphragms 24 and the second electrode plates 221, and thereby improving the safety performance of the battery cell 100.

[0068] Please refer to Figures 2 to 4 In one or more of the above optional embodiments, the number of the first pole pieces 211 is less than the number of the second pole pieces 221 .

[0069] The number of the first pole pieces 211 is relatively small, and the first pole piece group 21 may be a small pole piece group; the number of the second pole pieces 221 is relatively large, and the second pole piece group 22 may be a large pole piece group.

[0070] In the above scheme, the first diaphragm 23 matched with the first pole piece group 21 adopts a continuous structure, the number of first pole pieces 211 is small, and the length of the first pole piece 211 in the second direction Y is small, which can save the composite waiting time during stacking. The composite assembly time of multiple first pole pieces 211 and the first diaphragm 23 is short, thereby improving the assembly efficiency of the first pole piece group 21 and the first diaphragm 23.

[0071] Please refer to Figures 2 to 4In one or more of the above optional embodiments, the connecting portion 232 is located on at least one side of the first pole piece group 21 along the second direction Y.

[0072] The first pole piece group 21 and the second pole piece group 22 form a first step 25 at at least one end in the second direction Y, and the housing 1 forms a second step 15 corresponding to the first step 25 .

[0073] By setting a second step 15 on the outer shell 1, the second step 15 can be used to place components, so that the battery cell 100 can occupy other space in the battery compartment of the electrical device except 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 device.

[0074] According to the number of connecting parts 232, please refer to Figure 3 and Figure 4 , the connection portion 232 may be located on one side of the first pole piece group 21 along the second direction Y, or the connection portion 232 may also be located on both sides of the first pole piece group 21 along the second direction Y. For example, when the number of the connection portion 232 is one, the connection portion 232 is located on the side of the first pole piece group 21 close to the first step 25, or the connection portion 232 is located on the side of the first pole piece group 21 away from the first step 25. For another example, when the number of the connection portions 232 is two, along the length direction of the first diaphragm 23, two adjacent connection portions 232 are respectively located on both sides of the first pole piece group 21 along the second direction Y.

[0075] The connecting portion 232 is located on at least one side of the first electrode plate group 21 along the second direction Y. The first end of the negative electrode plate can be the end of one side of the negative electrode plate along the second direction Y. Along the second direction Y, a connecting portion 232 is arranged between the first end and the outer shell 1. The distance between the first end and the outer shell 1 is small. While improving the safety performance of the battery cell 100, the space utilization inside the outer shell 1 in the second direction Y can be improved, thereby improving the energy density of the battery cell 100.

[0076] In the above scheme, the connecting portion 232 can be located on one side of the first pole piece group 21 along the second direction Y, and the connecting portion 232 can also be located on both sides of the first pole piece group 21 along the second direction Y. In the second direction Y, the connecting portion 232 can separate the first pole piece 211 and the outer shell 1, so as to reduce the risk of short circuit between the first pole piece 211 and the outer shell 1, thereby improving the safety performance of the battery cell 100.

[0077] In some embodiments, along the second direction Y, the first end of the first electrode plate group 21 is aligned with the first end of the second electrode plate group 22 , and the second end of the electrode assembly 2 forms a first step 25 .

[0078] In some embodiments, the first end of the first pole piece group 21 is aligned with the first end of the second pole piece group 22, which means that the outer surface of the first end of the first pole piece group 21 is flush with the outer surface of the first end of the second pole piece group 22. The surface flushness can be understood in a broad sense, that is, the shortest distance between the plane where the outer surface of the first end of the first pole piece group 21 and the plane where the outer surface of the first end of the second pole piece group 22 is located along the second direction Y is within the error range, which can be understood as the outer surface of the first end of the first pole piece group 21 is flush with the outer surface of the first end of the second pole piece group 22.

[0079] Please refer to Figure 3 and Figure 4 In one or more of the above optional embodiments, 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 folding portion 231 is provided between the second end pole piece 222 and the first end pole piece 212.

[0080] The first end pole piece 212 refers to a first pole piece 211 at one end of the plurality of first pole pieces 211 along 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 .

[0081] The second end pole piece 222 refers to a second pole piece 221 at one end of the plurality of second pole pieces 221 along 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 .

[0082] The polarity of the second end pole piece 222 is opposite to that of the first end pole piece 212 . For example, the second end pole piece 222 may be the positive pole piece 26 , and the first end pole piece 212 may be the negative pole piece 27 ; or, the second end pole piece 222 may be the negative pole piece 27 , and the first end pole piece 212 may be the positive pole piece 26 .

[0083] A folded portion 231 is provided between the second end pole piece 222 and the first end pole piece 212. After the first diaphragm 23 separates the plurality of first pole pieces 211, a portion of the first diaphragm 23 is located 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 folded portion 231 provided between the first end pole piece 212 and the second end pole piece 222 has a longer length in the second direction Y, and when viewed along the first direction X, the folded portion 231 can shield 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.

[0084] In the above scheme, relative to the scheme in which the polarity of the second end electrode piece 222 is the same as the polarity of the first end electrode piece 212, the polarity of the second end electrode piece 222 is opposite to the polarity of the first end electrode piece 212, and the second end electrode piece 222 is separated from the first end electrode piece 212 by the folding portion 231, which can reduce redundant structural parts such as collectors and adhesive layers, can reduce the components between the first electrode piece group 21 and the second electrode piece group 22, can reduce the waste of internal space of the outer shell 1, reasonably utilize the space in the outer shell 1, facilitate the arrangement of more active materials in the outer shell 1, and facilitate the improvement of the energy density of the battery cell 100.

[0085] Please refer to Figure 3 and Figure 4 In one or more optional embodiments above, one of the multiple second electrode sheets 221 that is closest to the first electrode sheet group 21 is the second end electrode sheet 222, the second end electrode sheet 222 is the positive electrode sheet 26, and the second end electrode sheet 222 includes a first region 222a overlapping with the positive electrode sheet of the first electrode sheet group 21 (such as the first positive electrode sheet 26a) and a second region 222b that does not overlap with the positive electrode sheet of the first electrode sheet group 21 (such as the first positive electrode sheet 26a); along the first direction X, positive electrode active material layers 261 are provided on both sides of the first region 222a, and the positive electrode active material layer 261 is provided only on the side of the second region 222b away from the first electrode sheet group 21.

[0086] Figure 3 and Figure 4 The dotted line in may be a boundary line between the first region 222a and the second region 222b.

[0087] In some embodiments, the second end electrode piece 222 is a positive electrode piece 26, the first end electrode piece 212 can be a negative electrode piece 27, and a folding portion 231 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 1 and facilitating the improvement of the energy density of the battery cell 100.

[0088] The first region 222a and the second region 222b are two interconnected regions of the second end electrode sheet 222. When viewed along the first direction X, the first region 222a overlaps with the first positive electrode sheet 26a of the first electrode sheet group 21, and the part of the second end electrode sheet 222 in the first region 222a is provided with positive electrode active material layers 261 on both sides in the first direction X, and the positive electrode active material layer 261 on the side of the first region 222a facing the first electrode sheet group 21 can overlap with the positive electrode active material layer 261 in the first electrode sheet group 21.

[0089] It should be pointed out that the overlap mentioned in the present application can be understood as that the orthographic projections of the two components do not absolutely overlap along the projection direction, and tolerances may be allowed. For example, a tolerance of 0-0.5 mm may be allowed between the edges of the orthographic projections of the two components.

[0090] Along the first direction X, positive electrode active material layers 261 are arranged on both sides of the first region 222a, and the positive electrode active material layer 261 is arranged only on the side of the second region 222b away from the first electrode plate group 21. On the side of the second end electrode plate 222 facing the first electrode plate group 21, the second region 222b is not provided with a positive electrode active material layer 261, and on the side of the second end electrode plate 222 away from the first electrode plate group 21, the positive electrode active material layer 261 of the first region 222a and the positive electrode active material layer 261 of the second region 222b can be processed and formed simultaneously. For example, when the positive electrode active material layer 261 is coated on the side of the second end electrode sheet 222 facing the first electrode sheet group 21, the positive electrode active material layer 261 is coated only at the corresponding position of the first region 222a of the positive current collector 262; when the positive electrode active material layer 261 is coated on the side of the second end electrode sheet 222 facing away from the first electrode sheet group 21, the positive electrode active material layer 261 can be coated at the corresponding positions of the first region 222a and the second region 222b of the positive current collector 262 at the same time, so that the positive electrode active material layer 261 in the first region 222a and the positive electrode active material layer 261 in the second region 222b are continuous.

[0091] In the above scheme, the second end electrode sheet 222 is the positive electrode sheet 26, and the second end electrode sheet 222 is provided with positive electrode active material layers 261 on both sides of the first area 222a overlapping with the first positive electrode sheet 26a of the first electrode sheet group 21, so as to facilitate the movement of metal ions between the second electrode sheet 221 and the first electrode sheet 211, which is beneficial for the battery cell 100 to have a higher energy density; the second area 222b is only provided with the positive electrode active material layer 261 on the side away from the first electrode sheet group 21, which reduces the active materials that do not exert their capacity and avoids the active materials that do not exert their capacity occupying space, further reduces the energy density loss of the battery cell 100 in the first direction X, and at the same time reduces the use of active materials, reduces the production cost of the second end electrode sheet 222, and thus reduces the production cost of the battery cell 100.

[0092] Please refer to Figure 5 and Figure 6 , Figure 5 This is a schematic diagram of the structure of the electrode assembly provided in some other embodiments of the present application. Figure 6 for Figure 5In one or more optional embodiments above, the one closest to the first electrode set 21 among the plurality of second electrode sheets 221 is the second end electrode sheet 222, the second end electrode sheet 222 is the positive electrode sheet 26, and the second end electrode sheet 222 includes a first region 222a overlapping with the positive electrode sheet (such as the first positive electrode sheet 26a) of the first electrode set 21 and a second region 222b not overlapping with the positive electrode sheet (such as the first positive electrode sheet 26a) of the first electrode set 21; along the first direction X, positive electrode active material layers 261 are provided on both sides of the first region 222a, and positive electrode active material layers 261 are provided on both sides of the second region 222b.

[0093] Figure 5 and Figure 6 The dotted line in may be a boundary line between the first region 222a and the second region 222b.

[0094] When the second end electrode sheet 222 is the positive electrode sheet 26, the first end electrode sheet 212 may be the negative electrode sheet 27, and a folding portion 231 is provided between the first end electrode sheet 212 and the second end electrode sheet 222 to separate the first end electrode sheet 212 and the second end electrode sheet 222. In this case, metal ions can move between the first end electrode sheet 212 and the second end electrode sheet 222, so that the internal space of the housing 1 is reasonably utilized, which is conducive to improving the energy density of the battery cell 100.

[0095] Positive electrode active material layers 261 are provided on both sides of the first region 222a and both sides of the second region 222b. During the preparation of the second end electrode sheet 222, when the positive electrode active material layer 261 is coated on the side of the second end electrode sheet 222 facing the first end electrode sheet 212, the positive electrode active material layer 261 is simultaneously coated on corresponding positions of the first region 222a and the second region 222b of the positive electrode collector 262; when the positive electrode active material layer 261 is coated on the side of the second end electrode sheet 222 away from the first end electrode sheet 212, the positive electrode active material layer 261 is simultaneously coated on corresponding positions of the first region 222a and the second region 222b of the positive electrode collector 262, so that the second end electrode sheet 222 has positive electrode active material layers 261 on both sides in the first direction X.

[0096] In the above scheme, the second end pole piece 222 is a positive pole piece 26, and the second end pole piece 222 is provided with a positive active material layer 261 on both sides of the thickness direction thereof, so as to facilitate the movement of metal ions between the second pole piece 221 and the first pole piece 211, which is conducive to the battery cell 100 having a higher energy density. At the same time, the second end pole piece 222 has a positive active material layer 261 on both sides in the first direction X. When the active material is applied to the side of the second end pole piece 222 facing the first pole piece group 21, the positive active material layer 261 can be applied to the first area 222a and the second area 222b at the same time. Compared with the case of applying only the first area 222a, there is no need to avoid the second area 222b during the application, which is convenient for applying the positive active material layer 261 and the process is simple. In addition, the second end pole piece 222 can be the same as the positive pole piece 26 in other second pole pieces 221, which is convenient for batch processing and manufacturing.

[0097] Please refer to Figure 7 and Figure 8 , Figure 7 This is a schematic diagram of the structure of the electrode assembly provided in some other embodiments of the present application. Figure 8 for Figure 7 In one or more optional embodiments above, the one of the plurality of 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 the negative pole piece 27, and the second end pole piece 222 includes a first region 222a overlapping with the first pole piece group 21 and a second region 222b not overlapping with the first pole piece group 21; along the first direction X, both sides of the first region 222a are provided with a negative electrode active material layer 271, and the second region 222b is provided with a negative electrode active material layer 271 only on the side away from the first pole piece group 21.

[0098] Figure 7 and Figure 8 The dotted line in 222a may be a boundary between the first region 222a and the second region 222b. The first region 222a overlaps with the entire first electrode set 21, that is, the first region 222a overlaps with the negative electrode of the first electrode set 21 (such as the first negative electrode 27a).

[0099] In some embodiments, the second end electrode piece 222 is a negative electrode piece 27, the first end electrode piece 212 can be a positive electrode piece 26, and a folding portion 231 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 1 and facilitating the improvement of the energy density of the battery cell 100.

[0100] The first region 222a and the second region 222b are two interconnected regions of the second end electrode sheet 222. When viewed along the first direction X, the first region 222a overlaps with the first electrode sheet group 21, and the negative electrode active material layer 271 is disposed on both sides of the portion of the second end electrode sheet 222 in the first region 222a in the first direction X, and the negative electrode active material layer 271 on the side of the first region 222a facing the first electrode sheet group 21 can overlap with the negative electrode active material layer 271 in the first electrode sheet group 21.

[0101] Along the first direction X, negative electrode active material layers 271 are arranged on both sides of the first region 222a, and the negative electrode active material layer 271 is arranged only on the side of the second region 222b away from the first electrode plate group 21. On the side of the second end electrode plate 222 facing the first electrode plate group 21, the second region 222b is not provided with a negative electrode active material layer 271. On the side of the second end electrode plate 222 away from the first electrode plate group 21, the negative electrode active material layer 271 of the first region 222a and the negative electrode active material layer 271 of the second region 222b can be processed and formed simultaneously. For example, when the negative electrode active material layer 271 is coated on the side of the second end electrode sheet 222 facing the first electrode sheet group 21, the negative electrode active material layer 271 is coated only at the corresponding position of the first region 222a of the negative electrode collector 272; when the negative electrode active material layer 271 is coated on the side of the second end electrode sheet 222 facing away from the first electrode sheet group 21, the negative electrode active material layer 271 can be coated at the corresponding positions of the first region 222a and the second region 222b of the negative electrode collector 272 at the same time, so that the negative electrode active material layer 271 in the first region 222a and the negative electrode active material layer 271 in the second region 222b are continuous.

[0102] In the above scheme, the second end electrode sheet 222 is a negative electrode sheet 27, and negative electrode active material layers 271 are provided on both sides of the first region 222a of the second end electrode sheet 222 overlapping with the first electrode sheet group 21, so as to facilitate the movement of metal ions between the second electrode sheet 221 and the first electrode sheet 211, which is beneficial for the battery cell 100 to have a higher energy density; the second region 222b is only provided with a negative electrode active material layer 271 on the side away from the first electrode sheet group 21, which reduces the active materials that do not exert their capacity and avoids the active materials that do not exert their capacity occupying space, further reduces the energy density loss of the battery cell 100 in the first direction X, and at the same time reduces the use of active materials, reduces the production cost of the second end electrode sheet 222, and thus reduces the production cost of the battery cell 100.

[0103] Please refer to Fig. 9 and Fig.10 , Fig. 9 This is a schematic diagram of the structure of the electrode assembly provided in some other embodiments of the present application. Fig.10 for Fig. 9In one or more optional embodiments above, the one closest to the first electrode set 21 among the plurality of second electrode sheets 221 is the second end electrode sheet 222, the second end electrode sheet 222 is the negative electrode sheet 27, and the second end electrode sheet 222 includes a first region 222a overlapping with the first electrode set 21 and a second region 222b not overlapping with the first electrode set 21; along the first direction X, negative electrode active material layers 271 are disposed on both sides of the first region 222a, and negative electrode active material layers 271 are disposed on both sides of the second region 222b.

[0104] Fig. 9 and Fig.10 The dotted line in 222a may be a boundary between the first region 222a and the second region 222b. The first region 222a overlaps with the entire first electrode set 21, that is, the first region 222a overlaps with the negative electrode of the first electrode set 21 (such as the first negative electrode 27a).

[0105] When the second end electrode sheet 222 is a negative electrode sheet 27, the first end electrode sheet 212 may be a positive electrode sheet 26, and a folding portion 231 is provided between the first end electrode sheet 212 and the second end electrode sheet 222 to separate the first end electrode sheet 212 and the second end electrode sheet 222. In this case, metal ions can move between the first end electrode sheet 212 and the second end electrode sheet 222, so that the internal space of the housing 1 is reasonably utilized, which is conducive to improving the energy density of the battery cell 100.

[0106] Negative electrode active material layers 271 are provided on both sides of the first region 222a and both sides of the second region 222b. During the preparation of the second end electrode sheet 222, when the negative electrode active material layer 271 is coated on the side of the second end electrode sheet 222 facing the first end electrode sheet 212, the negative electrode active material layer 271 is simultaneously coated on corresponding positions of the first region 222a and the second region 222b of the negative electrode collector 272; when the negative electrode active material layer 271 is coated on the side of the second end electrode sheet 222 away from the first end electrode sheet 212, the negative electrode active material layer 271 is simultaneously coated on corresponding positions of the first region 222a and the second region 222b of the negative electrode collector 272, so that the second end electrode sheet 222 has negative electrode active material layers 271 on both sides in the first direction X.

[0107] In the above scheme, the second end electrode sheet 222 is a negative electrode sheet 27, and the negative electrode sheet 27 is provided with a negative electrode active material layer 271 on both sides of the thickness direction thereof, so as to facilitate the movement of metal ions between the second electrode sheet 221 and the first electrode sheet 211, which is conducive to the battery cell 100 having a higher energy density. At the same time, the second end electrode sheet 222 has a negative electrode active material layer 271 on both sides in the first direction X. When the active material is applied to the side of the second end electrode sheet 222 facing the first electrode sheet group 21, the negative electrode active material layer 271 can be applied to the first area 222a and the second area 222b at the same time. Compared with the case of applying only the first area 222a, there is no need to avoid the second area 222b during the application, which is convenient for applying the negative electrode active material layer 271 and the process is simple. In addition, the second end electrode sheet 222 can be the same as the negative electrode sheet 27 in other second electrode sheets 221, which is convenient for batch processing and manufacturing.

[0108] Please refer to Figures 2 to 10 In one or more of the above optional embodiments, the one of the multiple first pole pieces 211 that is farthest from the second pole piece group 22 is the third end pole piece 213, the third end pole piece 213 is the positive pole piece 26, and the third end pole piece 213 is only provided with a positive electrode active material layer 261 on the side facing the second pole piece group 22; the one of the multiple second pole pieces 221 that is farthest from the first pole piece group 21 is the fourth end pole piece 223, the fourth end pole piece 223 is the positive pole piece 26, and the fourth end pole piece 223 is only provided with a positive electrode active material layer 261 on the side facing the first pole piece group 21.

[0109] 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 .

[0110] When the third end electrode sheet 213 is the positive electrode sheet 26, the positive electrode current collector 262 (see Figure 3 ) A positive electrode active material layer 261 is only provided on the surface facing the second electrode plate group 22, and a positive electrode current collector 262 of the third end electrode plate 213 is not provided with a positive electrode material layer on the surface facing away from the second electrode plate group 22, and the surface has an empty foil area.

[0111] 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 .

[0112] When the fourth end electrode sheet 223 is the positive electrode sheet 26, the positive electrode current collector 262 (see Figure 3 ) A positive electrode active material layer 261 is only provided on the surface facing the first electrode plate group 21, and a positive electrode current collector 262 of the fourth end electrode plate 223 is not provided with a positive electrode active material layer 261 on a surface away from the first electrode plate group 21, and the surface has an empty foil area.

[0113] In the above scheme, the third end electrode sheet 213 is a positive electrode sheet 26, and the third end electrode sheet 213 is provided with a positive electrode active material layer 261 only on the side facing the second electrode sheet group 22, which can reasonably utilize the internal space of the shell 1, and is convenient for improving the energy density of the battery cell 100; at the same time, the positive electrode active material layer 261 is not provided on the side of the third end electrode sheet 213 away from the second electrode sheet group 22, so as to facilitate bonding with other components (such as insulating parts, shell 1, etc.). The fourth end electrode sheet 223 is a positive electrode sheet 26, and the fourth end electrode sheet 223 is provided with a positive electrode active material layer 261 only on the side facing the first electrode sheet group 21, which can reasonably utilize the internal space of the shell 1, and is convenient for improving the energy density of the battery cell 100; at the same time, the positive electrode active material layer 261 is not provided on the side of the fourth end electrode sheet 223 away from the first electrode sheet group 21, so as to facilitate bonding with other components (such as insulating parts, shell 1, etc.).

[0114] Please refer to Figure 1 and Figure 2 In one or more of the above optional embodiments, the housing 1 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 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; 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.

[0115] 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 2 between the first wall 11 and the second wall 12 .

[0116] In some embodiments, the housing 1 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 .

[0117] 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.

[0118] 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 .

[0119] 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 15 .

[0120] 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 .

[0121] 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 .

[0122] In the above scheme, the second sub-wall 112 protrudes from the first sub-wall 111, the first connecting wall 113 connects the first sub-wall 111 and the second sub-wall 112, and the shell 1 is stepped so that the battery cell 100 can be adapted to a limited assembly space, thereby increasing the adaptability of the battery cell 100.

[0123] Please refer to Figure 2 According to some embodiments of the present application, the second sub-wall 112 and the first sub-wall 111 are spaced apart in the second direction Y, and the housing 1 also includes a third wall 13 and a fourth wall 14, and the third wall 13 and the fourth wall 14 are spaced apart along the second direction Y, the third wall 13 connects the second sub-wall 112 and the second wall 12, and the fourth wall 14 connects the first sub-wall 111 and the second wall 12.

[0124] Please refer to Fig.11 , Fig.11 for Figure 2 A partial enlarged view of the E of FIG. In some embodiments, the plurality of first electrode sheets 211 include a first positive electrode sheet 26a and a first negative electrode sheet 27a, and the first positive electrode sheet 26a and the first negative electrode sheet 27a are alternately arranged along the first direction X. Along the second direction Y, a connecting portion 232 is arranged between the end of the first negative electrode sheet 27a close to the first connecting wall 113 and the first connecting wall 113. In this case, the end of the first negative electrode sheet 27a close to the first connecting wall 113 is isolated from the first connecting wall 113 by the connecting portion 232. Along the second direction Y, the distance between the first negative electrode sheet 27a and the first connecting wall 113 can be smaller than the distance between the first negative electrode sheet 27a and the third wall 13, so as to improve the safety performance of the battery cell 100 while improving the space utilization rate inside the housing 1 in the second direction Y, which is conducive to improving the energy density of the battery cell 100.

[0125] In some embodiments, the plurality of first electrode sheets 211 include a first positive electrode sheet 26a and a first negative electrode sheet 27a, and the first positive electrode sheet 26a and the first negative electrode sheet 27a are alternately arranged along the first direction X, and along the second direction Y, a connecting portion 232 is arranged between the end of the first negative electrode sheet 27a close to the third wall 13 and the third wall 13. In this case, the end of the first negative electrode sheet 27a close to the third wall 13 is isolated from the third wall 13 by the connecting portion 232, and along the second direction Y, the distance between the first negative electrode sheet 27a and the third wall 13 can be smaller than the distance between the first negative electrode sheet 27a and the first connecting wall 113, so as to improve the safety performance of the battery cell 100, so as to improve the space utilization rate inside the housing 1 in the second direction Y, and to improve the energy density of the battery cell 100.

[0126] Please refer to Figure 1 In one or more of the above optional embodiments, the battery cell 100 further includes a positive electrode tab 28 and a negative electrode tab 29, and the positive electrode tab 28 and the electrode assembly 2 (please refer to Figure 2 ) is electrically connected to the positive electrode tab 26 of the electrode assembly 2, and the negative electrode tab 29 is electrically connected to the negative electrode tab 27 of the electrode assembly 2. The positive electrode tab 28 and the negative electrode tab 29 can be located on the same side of the electrode assembly 2, or the positive electrode tab 28 and the negative electrode tab 29 can be located on both sides of the electrode assembly 2. The positive electrode tab 28 and the negative electrode tab 29 are used to output or input electrical energy to or from the electrode assembly 2.

[0127] In some embodiments, please refer to Figure 1 The positive electrode tab 28 and the negative electrode tab 29 can extend out of the housing 1 to facilitate connection with an external conductive member. For example, the positive electrode tab 28 and the negative electrode tab 29 can extend out from one end of the housing 1 in the third direction Z.

[0128] In some embodiments, the positive electrode tab 28 and the negative electrode tab 29 may both be located in the housing 1, the housing 1 is provided with a positive electrode terminal, the positive electrode terminal is provided in the housing 1, and the positive electrode tab 28 is electrically connected to the positive electrode terminal through a positive electrode adapter. The housing 1 may be provided with a negative electrode terminal, the negative electrode terminal is provided in the housing 1, and the negative electrode tab 29 is electrically connected to the negative electrode terminal through a negative electrode adapter; or, the negative electrode tab 29 is electrically connected to the housing 1 through a negative electrode adapter.

[0129] 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 15 is used to avoid components arranged in the battery compartment.

[0130] The electric device may be any terminal or system using the battery cell 100 as described above.

[0131] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

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 first diaphragm comprises a plurality of folded portions and at least one connecting portion, wherein the plurality of folded portions are arranged at intervals along the first direction, a first pole piece is arranged between two adjacent folded portions, and the connecting portion connects two adjacent folded portions; A plurality of second diaphragms are arranged at intervals and are not connected along the first direction, and a second pole piece is arranged between two adjacent second diaphragms.

2. The battery cell according to claim 1, characterized in that: The number of the first pole pieces is less than the number of the second pole pieces.

3. The battery cell according to claim 1, characterized in that: The connecting portion is located on at least one side of the first pole piece group along the second direction.

4. The battery cell according to claim 1, characterized in that: The one of the multiple first pole pieces that is closest to the second pole piece group is the first end pole piece, and the one of the multiple second pole pieces that is closest to the first pole piece group is the second end pole piece. The polarity of the second end pole piece is opposite to that of the first end pole piece, and the folding portion is arranged between the second end pole piece and the first end pole piece.

5. 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 pole piece is a positive pole piece, and the second end pole piece includes a first area overlapping with the positive pole piece of the first pole piece group and a second area not overlapping with the positive pole piece of the first pole piece group; Along the first direction, positive electrode active material layers are disposed on both sides of the first region, and positive electrode active material layers are disposed only on one side of the second region away from the first electrode assembly.

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 pole piece is a positive pole piece, and the second end pole piece includes a first area overlapping with the positive pole piece of the first pole piece group and a second area not overlapping with the positive pole piece of the first pole piece group; Along the first direction, positive electrode active material layers are disposed on both sides of the first region, and positive electrode active material layers are disposed on both sides of the second region.

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

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

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

10. The battery cell according to any one of claims 1 to 9, 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 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; 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.

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

Images