Battery cell and electrical device

Abstract

Provided in the embodiments of the present application are a battery cell and an electrical device. The battery cell comprises an electrode assembly, the electrode assembly being a stacked structure; the electrode assembly comprises, stacked in a first direction, a plurality of first electrode sheets and a plurality of second electrode sheets, the polarity of the first electrode sheets and that of the second electrode sheets being opposite to each other; each first electrode sheet comprises a first current collector and a first active material layer; each first current collector comprises a first main body area and a first empty foil area which are connected to each other, the surface of the first main body area being provided with the first active material layer, and the surface of the first empty foil area not being provided with the first active material layer; each second electrode sheet is provided with a first notch, a first empty foil area being exposed to the first notch in the first direction; each first current collector is provided with a first gap, the first gap being arranged between the first empty foil area and the first main body area, so that the first empty foil area can move with respect to the first main body area along a joint between the first empty foil area and the first main body area. The technical solution of the embodiments of the present application can improve the reliability of battery cells.

Description

Battery cells and electrical devices CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese patent application CN202410251170.0, filed on March 5, 2024, entitled “Battery Cell and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of battery cell technology, and more specifically, to a battery cell and an electrical device. Background Art

[0003] During the production of battery cells, when assembling the stacked electrode assembly, it is necessary to weld the empty foil areas of the anode and cathode sheets to the adapter, and then bend the welded structure to reduce its occupation of the internal space of the battery cell.

[0004] The cathode electrode sheet includes a cathode current collector and a cathode active material layer, the cathode current collector includes a cathode main body area and a cathode empty foil area, the cathode main body area is provided with a cathode active material layer, and the cathode empty foil area is not provided with a cathode active material layer; the anode electrode sheet includes an anode current collector and an anode active material layer, the anode current collector includes an anode main body area and a cathode empty foil area, the anode main body area is provided with an anode active material layer, and the anode empty foil area is not provided with an anode active material layer.

[0005] In the existing manufacturing process for cathode and anode electrodes, the multi-layered cathode hollow foil area is folded together and welded to the cathode adapter, and the anode hollow foil area is folded together and welded to the anode adapter. When the hollow foil area has a long connection with the main body, the electrode assembly expands and contracts during the charge and discharge cycles of the battery cell, which can easily cause cracks at the connection between the hollow foil area and the main body, reducing the reliability of the battery cell. Summary of the Invention

[0006] The purpose of this application is to provide a battery cell and an electrical device that can improve the reliability of the battery cell.

[0007] This application is achieved through the following technical solutions:

[0008] In a first aspect, an embodiment of the present application provides a battery cell comprising an electrode assembly. The electrode assembly is a laminated structure, comprising a plurality of first pole pieces and a plurality of second pole pieces stacked along a first direction, the first pole piece and the second pole piece having opposite polarity. The first pole piece comprises a first current collector and a first active material layer, the first current collector comprises a first main body region and a first hollow foil region connected to each other, the surface of the first main body region is provided with a first active material layer, and the surface of the first hollow foil region is not provided with a first active material layer. The second pole piece has a first notch, and along the first direction, the first hollow foil region is exposed to the first notch. The first current collector has a first gap, and the first gap is provided between the first hollow foil region and the first main body region, so that the first hollow foil region can move relative to the first main body region along the connection with the first main body region.

[0009] According to the battery cell of the embodiment of the present application, the provision of the first slit, on the one hand, can provide a degree of freedom for the multiple first hollow foil areas, facilitating the folding of the multiple first hollow foil areas, and can reduce the risk of the first electrode sheet being torn at the connection between the first hollow foil area and the first main area when the multiple first hollow foil areas are folded. On the other hand, during the operation of the battery cell, it can reduce the risk of the first electrode sheet being torn at the connection between the first hollow foil area and the first main area due to expansion and contraction of the electrode assembly, thereby improving the reliability of the battery cell. At the same time, the provision of the first slit can provide a clearance space between the first hollow foil area and the second electrode sheet, thereby providing insulation.

[0010] In one or more of the above optional embodiments, along the length direction and the width direction of the first pole piece, the first hollow foil area does not protrude from the first main body area.

[0011] In the above solution, the first empty foil area does not protrude from the first main area. On the one hand, the first main area can extend to the end of the first empty foil area, and the first main area can have a larger area. On the other hand, the risk of interference between the first empty foil area and other components can be reduced.

[0012] In one or more of the above optional embodiments, the first empty foil area is located at a first corner of the first pole piece.

[0013] In the above solution, the first empty foil area is located at the first corner of the first pole piece, which is convenient for processing and manufacturing.

[0014] In one or more of the above optional embodiments, one end of the first slit extends to an edge of the first pole piece.

[0015] In the above solution, the first slit extends to the edge of the first pole piece to facilitate processing and manufacturing. The extension direction of the first slit can be parallel to the length direction or width direction of the first pole piece.

[0016] In one or more optional embodiments above, the first empty foil area includes a first edge and a second edge adjacent to each other, the first edge is connected to the first main area, and a first gap is formed between the second edge and the first main area.

[0017] In the above solution, the first edge is connected to the first main body area, and a first gap is formed between the second edge and the first main body area to facilitate the folding of multiple first empty foil areas, thereby reducing the risk of tearing at the connection between the first empty foil area and the first main body area after the multiple first empty foil areas are folded.

[0018]

[0019] In one or more of the above optional embodiments, the first slit extends along the length direction or the width direction of the first pole piece.

[0020] In the above solution, the first slit extends along the length direction or the width direction of the first pole piece, which has a simple structure and is easy to process.

[0021] In one or more of the above optional embodiments, at least one of the following conditions is met:

[0022] (1) Along the first direction, the projected area of ​​the first empty foil area is S1, which satisfies 4mm 2 ≤S1≤50mm 2 ;

[0023] (2) Along the first direction, the projected area of ​​the first empty foil area is S1, and the projected area of ​​the first gap is S2, satisfying, 4mm 2 ≤S1+S2≤51mm 2 ;

[0024] (3) The width of the first gap is K1, which satisfies 0<K1≤0.1mm;

[0025] (4) Along the first direction, the projected area of ​​the first main body region is S3, the length of the first pole piece is L, and the width of the first pole piece is W, satisfying S3 / (L*W)≥99%.

[0026] In the above solution, the projected area of ​​the first empty foil area meets the above range (4mm 2 ≤S1≤50mm 2 ), on the one hand, it is convenient to connect the first empty foil area with the adapter, on the other hand, the first empty foil area can occupy a smaller space, and the first active material layer can occupy a larger space, so that the battery cell can have a higher energy density. The sum of the projected area of ​​the first empty foil area and the projected area of ​​the first gap satisfies the above relationship (4mm 2 ≤S1+S2≤51mm 2), on the one hand, it can meet the connection area requirements of the first empty foil area and the adapter, and on the other hand, it can occupy a smaller space, so that the first active material layer can occupy a larger space. The width of the first gap satisfies the above relationship (0<K1≤0.1mm). On the one hand, it reduces the risk of short circuit between the first empty foil area and the second electrode, and on the other hand, it enables the first empty foil area and the adapter to have a larger connection area. The ratio of the projected area of ​​the first main body area to the product of the length and width of the first electrode satisfies the above relationship (S3 / (L*W)≥99%), so that the battery cell has a higher energy density.

[0027] In one or more optional embodiments above, the second electrode piece includes a second current collector and a second active material layer, the second current collector includes a second main body area and a second empty foil area connected to each other, the second main body area is provided with a second active material layer, and the surface of the second empty foil area is not provided with a second active material layer; the first electrode piece has a second notch, and along the first direction, the second empty foil area is exposed to the second notch; the second current collector has a second gap, and the second gap is provided between the second empty foil area and the second main body area, so that the second empty foil area can move relative to the first main body area along the connection with the second main body area.

[0028] In the above solution, the provision of the second slit, on the one hand, can provide a degree of freedom for the multiple second hollow foil areas, facilitating their folding, and can reduce the risk of the second electrode sheet being torn at the connection between the second hollow foil areas and the second main body area when the multiple second hollow foil areas are folded. On the other hand, during the operation of the battery cell, it can reduce the risk of the second electrode sheet being torn at the connection between the second hollow foil areas and the second main body area due to expansion and contraction of the electrode assembly, thereby improving the reliability of the battery cell. At the same time, the provision of the second slit can provide a clearance space between the second hollow foil areas and the first electrode sheet, thereby providing insulation.

[0029] In one or more optional embodiments above, the width of the first electrode is W, the thickness of the battery cell is H, along the first direction, the projected area of ​​the first empty foil area is S1, the projected area of ​​the first gap is S2, and the projected area of ​​the second gap is S4, satisfying S1+S2+S4<3.6*W.

[0030] In the above solution, the sum of the projected area of ​​the first empty foil area, the projected area of ​​the first gap and the projected area of ​​the second notch satisfies the above relationship, so that the battery cell has more first active material layers and a higher energy density.

[0031] In one or more of the above optional embodiments, when H>7 mm, S1+S2+S4<3.6*W.

[0032] In the above solution, when H>7mm, the projected area of ​​the first empty foil area, the projected area of ​​the first gap and the projected area of ​​the second notch satisfy the above relationship, the area of ​​the first active material layer is larger, so that the battery cell has a higher energy density.

[0033] In one or more of the above optional embodiments, when H≤7 mm, S1+S2+S4<1.6*W.

[0034] In the above solution, when H≤7mm, the projected area of ​​the first empty foil area, the projected area of ​​the first gap and the projected area of ​​the second notch satisfy the above relationship, the area of ​​the first active material layer is larger, so that the battery cell has a higher energy density.

[0035] In one or more optional embodiments above, along the first direction, the projection area of ​​the second notch is S4, which satisfies the following conditions: 4 mm 2 ≤S4≤50mm 2 .

[0036] In the above solution, the projected area of ​​the second notch satisfies the above relationship, and the first active material layer can have a larger area, so that the battery cell has a higher energy density.

[0037] In one or more of the above optional embodiments, the battery cell further includes a packaging bag, a first adapter and a second adapter, the electrode assembly is accommodated in the packaging bag, the first adapter is electrically connected to multiple first empty foil areas and extends out of the packaging bag, and the second adapter is electrically connected to multiple second empty foil areas and extends out of the packaging bag.

[0038] In the above solution, the electrode assembly is housed in a packaging bag, and the battery cell can be a soft-pack battery cell with a high energy density. The first adapter extends out of the packaging bag, and the second adapter extends out of the packaging bag to facilitate connection with other components, facilitating the transfer of electrical energy from the electrode assembly to or from the packaging bag.

[0039] In one or more optional embodiments above, the first adapter is arranged at one end of the first pole piece in the length direction, and along the length direction of the first pole piece, the minimum distance between the first main body area and the inner wall of the packaging bag is G, satisfying G≤0.7mm.

[0040] In the above solution, the minimum distance between the first main body area and the inner wall of the packaging bag satisfies the above relationship, and the space utilization rate inside the packaging bag is high, so that the battery cell has a higher energy density.

[0041] In one or more optional embodiments above, the first electrode piece is an anode electrode piece, the second electrode piece is a cathode electrode piece, and the width of the second gap is K2, satisfying K2>K1.

[0042] In the above solution, the second main body area exceeds the first main body area, and the width of the second gap is greater than that of the first gap, which can reduce the risk of short circuit between the second empty foil area and the first main body area.

[0043] In one or more of the above optional embodiments, the width of the second gap is K2, which satisfies 0.1 mm < K2 ≤ 1 mm.

[0044] In the above scheme, the width of the second gap satisfies the above relationship. On the one hand, it is convenient for processing and manufacturing, so that there is a larger distance between the second empty foil area and the first electrode, reducing the risk of short circuit between the anode and cathode. On the other hand, it allows the second empty foil area to have a larger area, so as to facilitate the connection between the second empty foil area and the adapter.

[0045] In one or more optional embodiments above, the battery cell further includes a diaphragm, which is disposed between the adjacent first electrode piece and the second electrode piece, and the diaphragm has a third notch and a fourth notch. Along the first direction, the first empty foil area is exposed to the third notch, and the second empty foil area is exposed to the fourth notch.

[0046] In the above scheme, the setting of the diaphragm can insulate and isolate the first electrode piece and the second electrode piece; the setting of the third notch can facilitate the collapse of the first empty foil area, so that multiple first empty foil areas can be connected to the first adapter; the setting of the fourth notch can facilitate the collapse of the second empty foil area, so that multiple second empty foil areas can be connected to the second adapter.

[0047] In a second aspect, an embodiment of the present application further provides an electrical device, which includes a battery cell as provided in any of the above embodiments, and the battery cell is used to provide electrical energy.

[0048] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. 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 relevant drawings can be obtained based on these drawings without creative work.

[0050] FIG1 is an exploded view of the structure of a battery cell provided in some embodiments of the present application;

[0051] FIG2 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0052] FIG3 is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application;

[0053] FIG4 is a schematic structural diagram of a first pole piece provided in some embodiments of the present application;

[0054] FIG5 is a schematic structural diagram of a first pole piece provided in other embodiments of the present application;

[0055] FIG6 is a schematic structural diagram of a first pole piece provided in yet other embodiments of the present application;

[0056] FIG7 is a schematic structural diagram of a second pole piece provided in some embodiments of the present application;

[0057] FIG8 is a schematic structural diagram of a second pole piece provided in other embodiments of the present application;

[0058] FIG9 is a schematic structural diagram of a second pole piece provided in yet other embodiments of the present application;

[0059] FIG10 is a schematic structural diagram of a diaphragm provided in some embodiments of the present application.

[0060] Icons: 100-cell; 10-electrode assembly; 11-first pole piece; 11a-first corner; 11b-second corner; 111-first current collector; 112-first active material layer; 113-first main body area; 114-first empty foil area; 115-first gap; 116-first edge; 117-second edge; 118-second notch; 12-second pole piece; 12a-third corner; 12b-fourth corner; 121-first notch; 122-first Second current collector; 123-second active material layer; 124-second main body area; 125-second empty foil area; 126-second gap; 127-third edge; 128-fourth edge; 13-diaphragm; 13a-fifth corner; 13b-sixth corner; 131-third notch; 132-fourth notch; 20-packaging bag; 30-first adapter; 40-second adapter; X-first direction; Y-length direction of the first electrode piece; Z-width direction of the first electrode piece. DETAILED DESCRIPTION

[0061] 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.

[0062] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0063] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0064] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0065] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0066] The term "multiple" in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0067] The battery cell provided in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0068] 1 to 5 , an embodiment of the present application provides a battery cell 100 including an electrode assembly 10. The electrode assembly 10 is a laminated structure comprising a plurality of first electrode sheets 11 and a plurality of second electrode sheets 12 stacked along a first direction X, wherein the first electrode sheets 11 and the second electrode sheets 12 have opposite polarities.

[0069] The first pole piece 11 may be a cathode pole piece, and the second pole piece 12 may be an anode pole piece; or the first pole piece 11 may be an anode pole piece, and the second pole piece 12 may be a cathode pole piece.

[0070] The plurality of first pole pieces 11 and the plurality of second pole pieces 12 are staggered along the first direction X. An isolation structure (such as a diaphragm) is provided between two adjacent first pole pieces 11 and second pole pieces 12 to insulate and isolate the first pole piece 11 from the second pole piece 12 .

[0071] The first pole piece 11 and the second pole piece 12 are sheet-shaped structures, and the first pole piece 11 and the second pole piece 12 can both be rectangular.

[0072] Please refer to Figures 2, 4 and 5. The first electrode 11 includes a first current collector 111 and a first active material layer 112. The first current collector 111 includes a first main area 113 and a first empty foil area 114 that are connected to each other. The first active material layer 112 is provided on the surface of the first main area 113, and the first active material layer 112 is not provided on the surface of the first empty foil area 114.

[0073] The first active material layer 112 may be provided on both sides of the first body region 113 in the thickness direction.

[0074] 3 , the second electrode 12 has a first notch 121 . Along the first direction X, the first empty foil region 114 is exposed in the first notch 121 .

[0075] The first empty foil area 114 can be arranged at the edge of the first pole piece 11. For example, as shown in Figure 5, the first empty foil area 114 can be located at a corner of the first pole piece 11, or, as shown in Figure 4, the first empty foil area 114 can be located in the area between two corners of the first pole piece 11.

[0076] The first current collector 111 has a first gap 115 , which is disposed between the first empty foil region 114 and the first main region 113 , so that the first empty foil region 114 can move relative to the first main region 113 along the connection with the first main region 113 .

[0077] The first slit 115 is provided along a portion of the boundary between the first hollow foil region 114 and the first main body region 113 .

[0078] The first slit 115 separates the first empty foil area 114 from the first main area 113. For example, during the processing of the first electrode 11, the first current collector 111 is an integral structure, and the first active material layer 112 is coated on a partial area of ​​the first current collector 111 to form the first main area 113. The area of ​​the first current collector 111 where the first active material layer 112 is not provided forms the first empty foil area 114. The first slit 115 is cut at the connection between the first empty foil area 114 and the first main area 113 to separate the first empty foil area 114 from the partial connection area of ​​the first main area 113.

[0079] When the first empty foil area 114 and the first main area 113 have multiple connection boundaries or the connection boundary between the first empty foil area 114 and the first main area 113 is long, when the multiple first empty foil areas 114 are gathered together, the connection boundary between the first empty foil area 114 and the first main area 113 is easily torn; or, during the charge and discharge cycle of the battery cell 100, the expansion and contraction of the electrode assembly 10 easily causes the connection boundary between the first main area 113 and the first empty foil area 114 to be torn. In the present application, a first slit 115 is provided at a portion of the boundary between the first empty foil area 114 and the first main area 113. When the multiple first empty foil areas 114 are gathered together, the multiple first empty foil areas 114 can be provided with a degree of freedom, reducing the risk of the multiple first empty foil areas 114 being torn at the connection with the first main area 113. At the same time, during the charge and discharge cycle of the battery cell 100, the risk of the connection between the first empty foil area 114 and the first main area 113 can be reduced.

[0080] According to the battery cell 100 of the embodiment of the present application, the provision of the first slit 115, on the one hand, can provide a degree of freedom for the multiple first hollow foil areas 114, facilitating the collapse of the multiple first hollow foil areas 114, and can reduce the risk of the first electrode sheet 11 being torn at the connection between the first hollow foil area 114 and the first main area 113 when the multiple first hollow foil areas 114 are collapsed. On the other hand, during the operation of the battery cell 100, the risk of the first electrode sheet 11 being torn at the connection between the first hollow foil area 114 and the first main area 113 due to expansion and contraction of the electrode assembly 10 can be reduced, thereby improving the reliability of the battery cell 100. At the same time, the provision of the first slit 115 can provide a clearance space between the first hollow foil area 114 and the second electrode sheet 12, thereby providing insulation.

[0081] 4 and 5 , in one or more of the above optional embodiments, along the length direction Y of the first pole piece, the first hollow foil region 114 does not protrude from the first main body region 113 .

[0082] In the above scheme, on the one hand, the first main body area 113 can extend to the end of the first empty foil area 114 in the length direction Y of the first electrode, so that the first main body area 113 can have a larger area, the area of ​​the first active material layer 112 is larger, and the battery cell 100 has a higher energy density; on the other hand, the risk of interference between the first empty foil area 114 and other components can be reduced.

[0083] Referring to FIG. 6 , in some embodiments, along the width direction Z of the first electrode sheet, the first hollow foil region 114 does not protrude beyond the first main body region 113 .

[0084] In the above scheme, on the one hand, the first main body area 113 can extend to the end of the first empty foil area 114 in the width direction Z of the first electrode, so that the first main body area 113 can have a larger area, the area of ​​the first active material layer 112 is larger, and the battery cell 100 has a higher energy density; on the other hand, the risk of interference between the first empty foil area 114 and other components can be reduced.

[0085] 5 and 6 , in one or more of the above optional embodiments, the first empty foil area 114 is located at the first corner 11 a of the first pole piece 11 .

[0086] The first corner 11 a may be defined by two adjacent edges of the first pole piece 11 .

[0087] In the above solution, the first empty foil area 114 is located at the first corner 11 a of the first pole piece 11 , which is convenient for processing and manufacturing.

[0088] 4 to 6 , in one or more of the above optional embodiments, one end of the first slit 115 extends to the edge of the first pole piece 11 .

[0089] The extension direction of the first slit 115 may be parallel to the length direction Y of the first pole piece or the width direction Z of the first pole piece.

[0090] Taking the extension direction of the first slit 115 as a straight line as an example, in the extension direction of the first slit 115 , the length of the first slit 115 is less than or equal to the length of the first empty foil area 114 .

[0091] For example, in the extending direction of the first slit 115 , the length of the first slit 115 is 1 / 4, 1 / 2, 2 / 3, 4 / 5, etc., of the length of the first empty foil area 114 .

[0092] During the processing of the first pole piece 11 , the first pole piece 11 may be cut starting from the edge of the first pole piece 11 to form a first slit 115 .

[0093] In the above solution, the first slit 115 extends to the edge of the first pole piece 11 to facilitate processing and manufacturing. The extension direction of the first slit 115 can be parallel to the length direction Y or the width direction Z of the first pole piece.

[0094] 5 and 6 , in one or more of the above optional embodiments, the first empty foil area 114 includes adjacent first and second edges 116 and 117 , the first edge 116 is connected to the first main area 113 , and a first gap 115 is formed between the second edge 117 and the first main area 113 .

[0095] The first edge 116 and the second edge 117 are adjacently disposed, and the first edge 116 and the second edge 117 are not collinear.

[0096] The first edge 116 and the first main body region 113 have a common boundary, and the second edge 117 is spaced apart from the first main body region 113 such that a first gap 115 is formed between the second edge 117 and the first main body region 113 .

[0097] In the above solution, the first edge 116 is connected to the first main area 113, and a first gap 115 is formed between the second edge 117 and the first main area 113, so as to facilitate the folding of the multiple first empty foil areas 114, thereby reducing the risk of the connection between the first empty foil areas 114 and the first main area 113 being torn after the multiple first empty foil areas 114 are folded.

[0098] Referring to FIG. 6 , in one or more of the above optional embodiments, the length of the first edge 116 is smaller than the length of the second edge 117 .

[0099] The length of the first edge 116 is smaller than that of the second edge 117, so that the length of the first gap 115 can be longer. When the multiple first empty foil areas 114 are folded together, even if the first empty foil area 114 is bent in the length direction of the second edge 117, after the first empty foil area 114 is bent, the size of the first empty foil area 114 in the length direction of the second edge 117 is also larger, so that the multiple first empty foil areas 114 have a larger overlapping area.

[0100] In the above solution, the plurality of first empty foil areas 114 form steps distributed sequentially in the extension direction of the second edge 117. The length of the second edge 117 is larger than the length of the first edge 116, so that the plurality of first empty foil areas 114 can have more space to be folded, so that the plurality of first empty foil areas 114 can have a larger overlapping area in the extension direction of the second edge 117.

[0101] In some embodiments, the length of the first edge 116 is equal to the length of the second edge 117 .

[0102] In some embodiments, the length of the first edge 116 is greater than the length of the second edge 117 .

[0103] Referring to FIG. 5 , in one or more of the above optional embodiments, the first slit 115 extends along the length direction Y of the first pole piece.

[0104] Referring to FIG. 6 , in some embodiments, the first slit 115 extends along the width direction Z of the first pole piece.

[0105] In the above solution, the first slit 115 extends along the length direction Y of the first pole piece or the width direction Z of the first pole piece, and has a simple structure and is easy to process.

[0106] In one or more optional embodiments above, along the first direction X, the projection area of ​​the first empty foil area 114 is S1, which satisfies the following conditions: 4 mm 2 ≤S1≤50mm 2 .

[0107] The projected area of ​​the first empty foil region 114 can be acquired via an industrial camera or other image sensors.

[0108] Optionally, S1 can be but not limited to 4mm 2 , 6mm 2 , 8mm 2 , 10mm 2 , 12mm 2 , 14mm 2 , 16mm 2 , 18mm 2 , 20mm 2 , 22mm 2 , 24mm 2 , 26mm 2 , 28mm 2 , 30mm 2 , 32mm 2 , 34mm 2 , 36mm 2 , 38mm 2 , 40mm 2 , 42mm 2 , 44mm 2 , 46mm 2 , 48mm 2 , 50mm 2 wait.

[0109] Optionally, 8mm 2 ≤S1≤16mm 2 .

[0110] In the above solution, the projection area of ​​the first empty foil area 114 satisfies the above range (4mm2 ≤S1≤50mm 2 ), on the one hand, when S1≥4mm 2 When S1≤50mm, the first empty foil area 114 has a larger projected area, which is convenient for connecting the first empty foil area 114 with the adapter. On the other hand, when S1≤50mm 2 When the first empty foil area 114 can occupy a smaller space, the first active material layer 112 can occupy a larger space, so that the battery cell 100 can have a higher energy density.

[0111] In some embodiments, along the first direction X, the projection area of ​​the first empty foil area 114 is S1, and the projection area of ​​the first gap 115 is S2, which satisfies 4 mm. 2 ≤S1+S2≤51mm 2 .

[0112] The projected area of ​​the first slit 115 refers to the projected area of ​​the first slit 115 when viewed along the first direction X. The projected area of ​​the first slit 115 can be acquired via an industrial camera or other image sensors.

[0113] Optionally, S1+S2 can be but not limited to 4mm 2 , 5mm 2 , 10mm 2 , 15mm 2 , 20mm 2 , 25mm 2 , 30mm 2 , 35mm 2 , 40mm 2 , 45mm 2 , 50mm 2 , 51mm 2 wait.

[0114] Optionally, 8.02mm 2 ≤S1+S2≤16.2mm 2 .

[0115] Optionally, 0<S2≤1mm 2 .

[0116] When S2≤1mm 2 When the first slit 115 has a smaller projection area, the first empty foil area 114 can have a larger projection area, so that the first empty foil area 114 can be connected to the adapter easily.

[0117] Optionally, 0.02 mm 2 ≤S2≤0.2mm 2 .

[0118] Optionally, S2 may be, but is not limited to, 0.1 mm.2 , 0.2mm 2 , 0.3mm 2 , 0.4mm 2 , 0.5mm 2 , 0.6mm 2 , 0.7mm 2 , 0.8mm 2 , 0.9mm 2 , 1mm 2 .

[0119] The sum of the projected area of ​​the first empty foil region 114 and the projected area of ​​the first slit 115 satisfies the above relationship (4 mm 2 ≤S1+S2≤51mm 2 ), on the one hand, when S1+S2≥4mm 2 When S1+S2≤51mm, the connection area requirement between the first empty foil area 114 and the adapter can be met. On the other hand, when S1+S2≤51mm 2 When the first empty foil area 114 and the first gap 115 can occupy a smaller space, the first active material layer 112 can occupy a larger space.

[0120] In some embodiments, the width of the first gap 115 is K1, satisfying 0<K1≤0.1 mm.

[0121] Optionally, K1 may be, but is not limited to, 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, etc.

[0122] Optionally, 0.02mm≤K1≤0.08mm.

[0123] The width of the first gap 115 satisfies the above relationship (0<K1≤0.1mm). On the one hand, when K1>0, the first gap 115 has a larger width, reducing the risk of short circuit caused by cutting burrs near the first gap 115 and contact with the second pole piece 12. On the other hand, when K1≤0.1mm, the first empty foil area 114 can have a larger projected area, so that the first empty foil area 114 and the adapter have a larger connection area.

[0124] In some embodiments, along the first direction X, the projected area of ​​the first main region 113 is S3, the length of the first pole piece 11 is L, and the width of the first pole piece 11 is W, satisfying S3 / (L*W)≥99%.

[0125] The first electrode sheet 11 can be rectangular, and L*W can be the maximum area of ​​the first electrode sheet 11, that is, the area of ​​the first electrode sheet 11 before the first hollow foil region 114, the first slit 115, and the second notch are provided. During the manufacturing process of the first electrode sheet 11, the first active material layer 112 can be coated on the entire surface of the first current collector 111. The first active material layer 112 is then removed from a portion of the first electrode sheet 11, and the first slit 115 is cut in the region to form the first hollow foil region 114.

[0126] S3 / (L*W) may be a ratio of the projected area of ​​the first active material layer 112 in the first electrode sheet 11 . The larger S3 / (L*W) is, the larger the area of ​​the first active material layer 112 is, and the higher the energy density of the battery cell 100 is.

[0127] Alternatively, S3 / (L*W) may be, but is not limited to, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, etc.

[0128] Optionally, 99.2%≤S3 / (L*W)≤99.4%.

[0129] The ratio of the projected area of ​​the first main region 113 to the product of the length and width of the first electrode 11 satisfies the above relationship (S3 / (L*W)≥99%), and the first active material layer 112 has a larger area, so that the battery cell 100 has a higher energy density.

[0130] Please refer to Figures 2, 7 and 8. In one or more optional embodiments above, the second electrode 12 includes a second current collector 122 and a second active material layer 123. The second current collector 122 includes a second main body area 124 and a second hollow foil area 125 connected to each other. The second active material layer 123 is provided on the surface of the second main body area 124, and the second active material layer 123 is not provided on the surface of the second hollow foil area 125.

[0131] The second active material layer 123 may be provided on both sides of the second body region 124 in the thickness direction.

[0132] 3 , 7 and 8 , in some embodiments, the first electrode 11 has a second notch 118 , and along the first direction X, the second empty foil area 125 is exposed to the second notch 118 ; the second current collector 122 has a second slit 126 , and the second slit 126 is arranged between the second empty foil area 125 and the second main area 124 , so that the second empty foil area 125 can move relative to the second main area 124 along the connection with the second main area 124 .

[0133] The second slit 126 is provided along a portion of the boundary between the second empty foil region 125 and the second main body region 124 .

[0134] Along the first direction X, the second notch 118 does not overlap with the first notch 121 , so as to reduce the risk of short circuit caused by contact between the first empty foil area 114 and the second empty foil area 125 .

[0135] The second empty foil area 125 can be arranged at the edge of the second pole piece 12. For example, as shown in Figure 8, the second empty foil area 125 can be located at a corner of the second pole piece 12, or, as shown in Figure 7, the second empty foil area 125 can be located in the area between two corners of the second pole piece 12.

[0136] The second gap 126 separates the second empty foil area 125 from the second main area 124. For example, during the processing of the second electrode 12, the second current collector 122 is an integral structure, and the second active material layer 123 is coated on a partial area of ​​the second current collector 122 to form the second main area 124. The area of ​​the second current collector 122 where the second active material layer 123 is not provided forms the second empty foil area 125. The second gap 126 is cut at the connection between the second empty foil area 125 and the second main area 124 to separate the second empty foil area 125 from the partial connection area of ​​the second main area 124.

[0137] When the second empty foil area 125 and the second main area 124 have multiple connection boundaries or the connection boundary between the second empty foil area 125 and the second main area 124 is long, when the multiple second empty foil areas 125 are collapsed, the second empty foil area 125 is easily torn at the connection boundary between the second empty foil area 125 and the second main area 124; or, during the charge and discharge cycle of the battery cell 100, the expansion and contraction of the electrode assembly 10 can easily cause the connection boundary between the second main area 124 and the second empty foil area 125 to be torn. In the present application, second gaps 126 are provided at part of the boundary between the second empty foil area 125 and the second main area 124. When the multiple second empty foil areas 125 are collapsed, the multiple second empty foil areas 125 can be provided with a degree of freedom, reducing the risk of the multiple second empty foil areas 125 being torn at the connection with the second main area 124. At the same time, during the charge and discharge cycle of the battery cell 100, the risk of the second empty foil area 125 being torn at the connection with the second main area 124 can be reduced.

[0138] In the above solution, the provision of the second slit 126, on the one hand, can provide a degree of freedom for the multiple second empty foil areas 125, facilitating the collapse of the multiple second empty foil areas 125. This can reduce the risk of the second electrode sheet 12 being torn at the connection between the second empty foil areas 125 and the second main area 124 when the multiple second empty foil areas 125 are collapsed. On the other hand, during the operation of the battery cell 100, the risk of the second electrode sheet 12 being torn at the connection between the second empty foil areas 125 and the second main area 124 due to expansion and contraction of the electrode assembly 10 can be reduced, thereby improving the reliability of the battery cell 100. At the same time, the provision of the second slit 126 can provide a clearance space between the second empty foil areas 125 and the first electrode sheet 11, thereby providing insulation.

[0139] Please refer to Figure 1 and Figure 2. In one or more optional embodiments above, the battery cell 100 further includes a packaging bag 20 and a first adapter 30. The electrode assembly 10 is accommodated in the packaging bag 20. The first adapter 30 is electrically connected to the multiple first empty foil areas 114 and extends out of the packaging bag 20.

[0140] The battery cell 100 further includes a second adapter 40 , which is electrically connected to the plurality of second empty foil areas 125 and extends out of the packaging bag 20 .

[0141] In the above embodiment, the electrode assembly 10 is housed in the packaging bag 20. The battery cell 100 can be a soft-pack battery cell with a high energy density. The first adapter 30 and the second adapter 40 extend out of the packaging bag 20 to facilitate connection with other components and facilitate the transfer of electrical energy from the electrode assembly 10 to or from the packaging bag.

[0142] Referring to FIG. 3 , in one or more of the above optional embodiments, the first adapter 30 is disposed at one end of the first pole piece in the length direction Y.

[0143] Along the length direction Y of the first electrode piece, the minimum distance between the first main body area 113 and the inner wall of the packaging bag 20 is G, which satisfies G≤0.7 mm.

[0144] The first adapter 30 is arranged at one end of the length direction Y of the first electrode sheet. The length direction Y of the first electrode sheet can be parallel to the length direction of the battery cell 100. The first empty foil area 114 is arranged at one end of the length direction Y of the first electrode sheet to facilitate the connection between the first empty foil area 114 and the first adapter 30.

[0145] G may be the assembly gap between the electrode assembly 10 and the packaging bag 20 . In some embodiments, G may be referred to as a head gap.

[0146] Optionally, G may be, but is not limited to, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, etc.

[0147] In the above solution, the minimum distance G between the first main area 113 and the inner wall of the packaging bag 20 satisfies the above relationship (G≤0.7 mm), and the space utilization rate inside the packaging bag 20 is high, so that the battery cell 100 has a higher energy density.

[0148] In one or more optional embodiments above, along the first direction X, the projection area of ​​the second notch 118 is S4, which satisfies the following conditions: 4 mm 2 ≤S4≤50mm 2 .

[0149] The projected area S4 of the second notch 118 may be equal to the sum of the projected area S1 of the first empty foil region 114 and the area S2 of the first gap 115 .

[0150] The method for measuring the projected area of ​​the second notch 118 is: fill the outline of the first pole piece 11 , and the area defined by the edge outline of the first pole piece 11 constituting the second notch 118 is the area of ​​the second notch 118 .

[0151] Optionally, S4 can be but not limited to 4mm 2 , 6mm 2 , 8mm 2 , 10mm 2 , 12mm 2 , 14mm 2 , 16mm 2 , 18mm 2 , 20mm 2 , 22mm 2 , 24mm 2 , 26mm 2 , 28mm 2 , 30mm 2 , 32mm 2 , 34mm 2 , 36mm 2 , 38mm 2 , 40mm 2 , 42mm 2 , 44mm 2 , 46mm 2 , 48mm 2 , 50mm 2 wait.

[0152] In the above solution, the projected area of ​​the second notch 118 satisfies the above relationship (4mm 2 ≤S4≤50mm 2 ), on the one hand, when S4≥4mm 2 When S4≤50mm, the second notch 118 has a larger projected area to expose the first empty foil area 114. On the other hand, when S4≤50mm 2When the first active material layer 112 has a larger area, the battery cell 100 has a higher energy density.

[0153] In one or more optional embodiments above, along the first direction X, the projected area of ​​the first empty foil region 114 is S1, and the projected area of ​​the second notch 118 is S4, satisfying S1=S4.

[0154] In the above solution, the projected area of ​​the second notch 118 is equal to the projected area of ​​the first empty foil area 114 , so that the first electrode 11 can be provided with more first active material layers, and the battery cell 100 can have a higher energy density.

[0155] In the prior art, when the thickness of the battery cell 100 is greater than 7 mm, the maximum value of the minimum distance between the first main area 113 and the inner wall of the packaging bag 20 along the length direction Y of the first electrode sheet is 4 mm; when the thickness of the battery cell 100 is less than or equal to 7 mm, the maximum value of the minimum distance between the first main area 113 and the inner wall of the packaging bag 20 along the length direction Y of the first electrode sheet is 2 mm.

[0156] In the present application, along the length direction Y of the first electrode sheet, the minimum distance G between the first main area 113 and the inner wall of the packaging bag 20 is less than or equal to 0.7 mm, which can improve the space utilization inside the packaging bag 20 and increase the energy density of the battery cell 100.

[0157] In one or more optional embodiments above, the width of the first electrode 11 is W, the thickness of the battery cell 100 is H, and along the first direction X, the projected area of ​​the first empty foil area 114 is S1, the projected area of ​​the first gap 115 is S2, and the projected area of ​​the second notch 118 is S4, satisfying S1+S2+S4<3.6*W.

[0158] The thickness direction of the battery cell 100 is parallel to the first direction X.

[0159] In the above solution, the sum of the projected area of ​​the first empty foil area 114, the projected area of ​​the first gap 115 and the projected area of ​​the second notch 118 satisfies the above relationship (S1+S2+S4<3.6*W), so that the battery cell 100 has more first active material layers 112 and the battery cell 100 has a higher energy density.

[0160] For example, taking a battery cell 100 having a length of 80 mm, a width of 60 mm, and a thickness greater than 7 mm as an example, (1) in comparative example 1, along the length direction Y of the first electrode sheet, the first hollow foil area 114 is located between the first main body area 113 and the inner wall of the packaging bag 20; along the length direction Y of the first electrode sheet, the minimum distance between the first main body area 113 and the inner wall of the packaging bag 20 is 4 mm. (2) in embodiment 1 of the present application, along the length direction Y of the first electrode sheet, the minimum distance G between the first main body area 113 and the inner wall of the packaging bag 20 is 0.4 mm. The maximum projected area that can be increased by the first active material layer 112 relative to comparative example 1 is (4-0.4)*W. As long as S1+S2+S4 is less than (4-0.4)*W, the projected area of ​​the first active material layer 112 can be increased. Therefore, when S1+S2+S4<3.6*W, the projected area of ​​the first active layer of the present application can be increased relative to the prior art.

[0161] In one or more of the above optional embodiments, when H>7 mm, S1+S2+S4<3.6*W.

[0162] In the above solution, when H>7 mm, the projected area of ​​the first empty foil area 114, the projected area of ​​the first gap 115 and the projected area of ​​the second notch 118 satisfy the above relationship, and the area of ​​the first active material layer 112 is larger, so that the battery cell 100 has a higher energy density.

[0163] For example, taking a battery cell 100 having a length of 80 mm, a width of 60 mm, and a thickness less than or equal to 7 mm as an example, (1) in comparative example 2, along the length direction Y of the first electrode sheet, the first hollow foil area 114 is located between the first main body area 113 and the inner wall of the packaging bag 20; along the length direction Y of the first electrode sheet, the minimum distance between the first main body area 113 and the inner wall of the packaging bag 20 is 2 mm. (2) in embodiment 1 of the present application, along the length direction Y of the first electrode sheet, the minimum distance G between the first main body area 113 and the inner wall of the packaging bag 20 is 0.4 mm. The maximum projected area that can be increased by the first active material layer 112 relative to comparative example 2 is (2-0.4)*W. As long as S1+S2+S4 is less than (2-0.4)*W, the projected area of ​​the first active material layer 112 can be increased. Therefore, when S1+S2+S4<1.6*W, the projected area of ​​the first active layer of the present application can be increased relative to the prior art.

[0164] In one or more of the above optional embodiments, when H≤7 mm, S1+S2+S4<1.6*W.

[0165] In the above solution, when H≤7mm, the projected area of ​​the first empty foil area 114, the projected area of ​​the first gap 115 and the projected area of ​​the second notch 118 satisfy the above relationship, and the area of ​​the first active material layer 112 is larger, so that the battery cell 100 has a higher energy density.

[0166] 5 and 6 , in one or more optional embodiments above, the first empty foil area 114 is located at the first corner 11 a of the first pole piece 11 , and the second notch 118 is located at the second corner 11 b of the first pole piece 11 .

[0167] The first angular position 11a and the second angular position 11b may be two adjacent angular positions, or two non-adjacent angular positions, or two symmetrical angular positions.

[0168] The first empty foil area 114 is located at the first corner 11a of the first electrode 11, and the second notch 118 is located at the second corner 11b of the first electrode 11, so that there is a large distance between the first empty foil area 114 and the second notch 118, which can reduce the risk of short circuit between the first empty foil area 114 and the second empty foil area 125.

[0169] 8 and 9 , the second empty foil area 125 is located at the third corner 12 a of the second pole piece 12 , and the first notch 121 is located at the fourth corner 12 b of the second pole piece 12 .

[0170] The third angular position 12a and the fourth angular position 12b may be two adjacent angular positions, or two non-adjacent angular positions, or two symmetrical angular positions.

[0171] In the above solution, the first empty foil area 114 and the second notch 118 are located at two corners of the first pole piece 11 , and the second empty foil area 125 and the first notch 121 are located at two corners of the second pole piece 12 , which is convenient for processing and manufacturing.

[0172] Please refer to Figures 5, 6, 8 and 9. In one or more optional embodiments above, the first angle 11a and the second angle 11b are two adjacent angles of the first pole piece 11, and the third angle 12a and the fourth angle 12b are two adjacent angles of the second pole piece 12.

[0173] The first corner position 11a and the second corner position 11b are two adjacent corner positions of the first electrode piece 11, and the third corner position 12a and the fourth corner position 12b are two adjacent corner positions of the second electrode piece 12. Along the first direction X, the second empty foil area 125 is exposed at the second corner position 11b, and the first empty foil area 114 is exposed at the fourth corner position 12b, so that the first empty foil area 114 and the second empty foil area 125 can be located on the same side of the electrode assembly 10, so as to facilitate the connection of the first empty foil area 114 and the second empty foil area 125 with other components.

[0174] 7 and 8 , in one or more of the above optional embodiments, along the length direction of the second pole piece 12 , the second hollow foil region 125 does not protrude from the second main body region 124 .

[0175] The length direction of the second pole piece 12 is parallel to the length direction Y of the first pole piece.

[0176] In the above scheme, on the one hand, the second main body area 124 can extend to the end of the second empty foil area 125 in the length direction of the second electrode 12, so that the second main body area 124 can have a larger area, the area of ​​the second active material layer 123 is larger, and the battery cell 100 has a higher energy density; on the other hand, the risk of interference between the second empty foil area 125 and other components can be reduced.

[0177] 9 , in some embodiments, along the width direction of the second electrode 12 , the second hollow foil region 125 does not protrude from the second main body region 124 .

[0178] The width direction of the second pole piece 12 is parallel to the width direction Z of the first pole piece.

[0179] In the above scheme, on the one hand, the second main body area 124 can extend to the end of the second empty foil area 125 in the width direction of the second electrode 12, so that the second main body area 124 can have a larger area, the area of ​​the second active material layer 123 is larger, and the battery cell 100 has a higher energy density; on the other hand, the risk of interference between the second empty foil area 125 and other components can be reduced.

[0180] 8 and 9 , in one or more of the above optional embodiments, the second empty foil area 125 is located at the third position 12 a of the second pole piece 12 .

[0181] The third corner 12 a may be defined by two adjacent edges of the second pole piece 12 .

[0182] In the above solution, the second empty foil area 125 is located at the third position 12a of the second pole piece 12, which is convenient for processing and manufacturing.

[0183] 7 to 9 , in one or more of the above optional embodiments, one end of the second slit 126 extends to the edge of the second pole piece 12 .

[0184] The extension direction of the second slit 126 may be parallel to the length direction or the width direction of the second pole piece 12 .

[0185] Taking the extension direction of the second slit 126 as a straight line as an example, in the extension direction of the second slit 126 , the length of the second slit 126 is less than or equal to the length of the second empty foil area 125 .

[0186] During the processing of the second pole piece 12 , the second pole piece 12 may be cut starting from the edge of the second pole piece 12 to form a second slit 126 .

[0187] In the above solution, the second slit 126 extends to the edge of the second pole piece 12 to facilitate processing and manufacturing. The extension direction of the second slit 126 can be parallel to the length direction or width direction of the second pole piece 12.

[0188] 8 and 9 , in one or more of the above optional embodiments, the second empty foil area 125 includes adjacent third edges 127 and fourth edges 128 , the third edge 127 is connected to the second main area 124 , and a first gap 115 is formed between the fourth edge 128 and the second main area 124 .

[0189] The third edge 127 and the fourth edge 128 are adjacent to each other, and the third edge 127 and the fourth edge 128 are not collinear.

[0190] The third edge 127 and the second main body region 124 have a common boundary. The fourth edge 128 is spaced apart from the second main body region 124 , such that a second gap 126 is formed between the fourth edge 128 and the second main body region 124 .

[0191] In the above solution, the third edge 127 is connected to the second main body area 124, and a second gap 126 is formed between the fourth edge 128 and the second main body area 124, so as to facilitate the folding of the multiple second empty foil areas 125, thereby reducing the risk of the connection between the second empty foil areas 125 and the second main body area 124 being torn after the multiple second empty foil areas 125 are folded.

[0192] Referring to FIG. 9 , in one or more of the above optional embodiments, the length of the third edge 127 is smaller than the length of the fourth edge 128 .

[0193] The length of the third edge 127 is smaller than that of the fourth edge 128, so that the length of the second gap 126 can be longer. When the multiple second empty foil areas 125 are folded together, even if the second empty foil areas 125 are bent in the length direction of the fourth edge 128, after the second empty foil areas 125 are bent, the size of the second empty foil areas 125 in the length direction of the fourth edge 128 is also larger, so that the multiple second empty foil areas 125 have a larger overlapping area.

[0194] In the above solution, the length of the third edge 127 is smaller than the length of the fourth edge 128 , so as to facilitate the folding of the multiple second empty foil areas 125 and reduce the risk of the second electrode 12 being torn. The multiple second empty foil areas 125 can have a larger overlapping area in the extension direction of the fourth edge 128 .

[0195] Referring to FIG. 8 , in one or more of the above optional embodiments, the second slit 126 extends along the length direction of the second pole piece 12 .

[0196] Referring to FIG. 9 , in some embodiments, the second slit 126 extends along the width direction of the second pole piece 12 .

[0197] In the above solution, the second slit 126 extends along the length direction or the width direction of the second pole piece 12 , and has a simple structure and is easy to process.

[0198] In one or more optional embodiments above, along the first direction X, the projection area of ​​the second empty foil area 125 is S5, which satisfies the following conditions: 4 mm 2 ≤S5≤50mm 2 .

[0199] The projected area of ​​the second empty foil region 125 can be acquired via an industrial camera or other image sensors.

[0200] Optionally, S5 can be but not limited to 4mm 2 , 6mm 2 , 8mm 2 , 10mm 2 , 12mm 2 , 14mm 2 , 16mm 2 , 18mm 2 , 20mm 2 , 22mm 2 , 24mm 2 , 26mm 2 , 28mm 2 , 30mm 2 , 32mm 2 , 34mm 2 , 36mm 2 , 38mm 2 , 40mm 2 , 42mm 2 , 44mm 2 , 46mm 2 , 48mm 2 , 50mm 2 wait.

[0201] Optionally, 8mm 2 ≤S5≤16mm 2 .

[0202] In the above solution, the projected area of ​​the second empty foil area 125 satisfies the above range (4mm 2 ≤S5≤50mm 2 ), on the one hand, when S5≥4mm 2When S5≤50mm, the second empty foil area 125 has a larger projected area, which facilitates the connection between the second empty foil area 125 and the second adapter 40. 2 When the second empty foil area 125 is spaced smaller, the second active material layer 123 can occupy a larger space, so that the battery cell 100 can have a higher energy density.

[0203] In some embodiments, along the first direction X, the projection area of ​​the second empty foil area 125 is S5, and the projection area of ​​the second gap 126 is S6, which satisfies 4 mm. 2 ≤S5+S6≤51mm 2 .

[0204] The projected area of ​​the second slit 126 can be acquired via an industrial camera or other image sensors.

[0205] Optionally, S5+S6 can be but not limited to 4mm 2 , 5mm 2 , 10mm 2 , 15mm 2 , 20mm 2 , 25mm 2 , 30mm 2 , 35mm 2 , 40mm 2 , 45mm 2 , 50mm 2 , 51mm 2 wait.

[0206] Optionally, 8.02mm 2 ≤S5+S6≤16.2mm 2 .

[0207] Optionally, 0<S6≤1mm 2 .

[0208] When S6≤1mm 2 When the second slit 126 has a smaller projection area, the second empty foil area 125 can have a larger projection area, so that the second empty foil area 125 can be connected to the adapter easily.

[0209] Optionally, 0.02 mm 2 ≤S6≤0.2mm 2 .

[0210] Optionally, S6 may be, but is not limited to, 0.1 mm. 2 , 0.2mm 2 , 0.3mm 2 , 0.4mm 2 , 0.5mm 2, 0.6mm 2 , 0.7mm 2 , 0.8mm 2 , 0.9mm 2 , 1mm 2 .

[0211] The sum of the projected area of ​​the second empty foil region 125 and the projected area of ​​the second slit 126 satisfies the above relationship (4 mm 2 ≤S5+S6≤51mm 2 ), on the one hand, when S5+S6≥4mm 2 When S5+S6≤51mm, the connection area requirement between the second empty foil area 125 and the second adapter 40 can be met. On the other hand, when S5+S6≤51mm 2 When the second empty foil area 125 and the second gap 126 can occupy a smaller space, the second active material layer 123 can occupy a larger space.

[0212] In some embodiments, the first electrode 11 is an anode electrode, the second electrode 12 is a cathode electrode, the width of the second gap 126 is K2, and the width of the first gap 115 is K1, satisfying K2>K1.

[0213] The second main body region 124 extends beyond the first main body region 113 , and the width of the second slit 126 is greater than that of the first slit 115 , thereby reducing the risk of short circuit between the second empty foil region 125 and the first main body region 113 .

[0214] In some embodiments, the width of the second gap 126 is K2, which satisfies 0.1 mm < K2 ≤ 1 mm.

[0215] Optionally, K2 may be, but is not limited to, 0.11 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0216] Optionally, 0.2mm≤K2≤0.45mm.

[0217] The width of the second gap 126 satisfies the above relationship (0.1mm<K2≤1mm). On the one hand, when K2>0.1mm, the second gap 126 has a larger width, reducing the risk of cutting burrs near the second gap 126 contacting and short-circuiting with the first pole piece 11. On the other hand, when K2≤1mm, the second empty foil area 125 can have a larger projected area, so that the second empty foil area 125 and the second adapter 40 have a larger connection area.

[0218] During the manufacturing process of the electrode assembly 10, the size of the anode electrode is usually larger than that of the cathode electrode (referred to as the non-overlapping area of ​​the anode and cathode, also known as the OverHang area in some embodiments). Therefore, the width of the second gap 126 is greater than the width of the first gap 115, so that the distance between the second empty foil area 125 and the first main body area 113 is larger, so as to reduce the risk of contact between the second empty foil area 125 and the first main body area 113.

[0219] For example, when the second hollow foil region 125 is located at one end of the lengthwise direction of the second electrode sheet 12, the first main region 113 extends beyond the second main region 124 at the end of the second electrode sheet 12 where the second hollow foil region 125 is located. When viewed along the thickness direction of the electrode assembly 10, a portion of the projection of the first main region 113 overlaps with the second slit 126. The width of the second slit 126 is parallel to the lengthwise direction of the second electrode sheet 12. Therefore, the width of the second slit 126 is relatively large to avoid the first main region 113. The width of the second slit 126 needs to be greater than the dimension of the first main region 113 extending beyond the second main region 124. For example, when the dimension OH of the first main region 113 extending beyond the second main region 124 satisfies 0 < OH ≤ 0.9 mm, the width K2 of the second slit 126 satisfies 0.1 mm < K2 ≤ 1 mm. Alternatively, 0.1 ≤ OH ≤ 0.35 mm.

[0220] In some embodiments, along the first direction X, the projected area of ​​the second main region 124 is S7, the length of the second pole piece 12 is L2, and the width of the second pole piece 12 is W2, satisfying S7 / (L2*W2)≥99%.

[0221] The second electrode sheet 12 may be rectangular, and L2*W2 may be the maximum area of ​​the second electrode sheet 12, that is, the area of ​​the second electrode sheet 12 before the second hollow foil region 125, the second slit 126, and the first notch 121 are provided. During the manufacturing process of the second electrode sheet 12, the second active material layer 123 may be coated on the entire surface of the second current collector 122. The second active material layer is then removed from a portion of the second electrode sheet 12, and the second slit 126 is cut into the region to form the second hollow foil region 125.

[0222] S7 / (L2*W2) may be the projected area ratio of the second active material layer 123 in the second electrode sheet 12 . The larger S7 / (L2*W2) is, the larger the area of ​​the second active material layer 123 is, and the higher the energy density of the battery cell 100 is.

[0223] Optionally, S7 / (L2*W2) can be but is not limited to 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, etc.

[0224] Optionally, 99.2%≤S7 / (L2*W2)≤99.4%.

[0225] The ratio of the projected area of ​​the second main region 124 to the product of the length and width of the second electrode 12 satisfies the above relationship (S7 / (L2*W2)≥99%), and the second active material layer 123 has a larger area, so that the battery cell 100 has a higher energy density.

[0226] In one or more optional embodiments above, along the first direction X, the projection area of ​​the first notch 121 is S8, which satisfies 4 mm 2 ≤S8≤50mm 2 .

[0227] The projected area S8 of the first notch 121 may be equal to the sum of the projected area S5 of the second empty foil region 125 and the area S6 of the second gap 126 .

[0228] The method for measuring the projected area of ​​the first notch 121 is: fill the outline of the second pole piece 12 , and the area defined by the edge outline of the second pole piece 12 constituting the first notch 121 is the area of ​​the first notch 121 .

[0229] Optionally, S8 can be but not limited to 4mm 2 , 6mm 2 , 8mm 2 , 10mm 2 , 12mm 2 , 14mm 2 , 16mm 2 , 18mm 2 , 20mm 2 , 22mm 2 , 24mm 2 , 26mm 2 , 28mm 2 , 30mm 2 , 32mm 2 , 34mm 2 , 36mm 2 , 38mm 2 , 40mm 2 , 42mm 2 , 44mm 2 , 46mm 2 , 48mm 2 , 50mm 2 wait.

[0230] In the above solution, the projection area of ​​the first notch 121 satisfies the above relationship (4mm 2 ≤S8≤50mm 2 ), on the one hand, when S8≥4mm2 When S8≤50mm, the first notch 121 has a larger area to expose the second empty foil area 125. On the other hand, when S8≤50mm 2 When the second active material layer 123 has a larger area, the battery cell 100 has a higher energy density.

[0231] In one or more optional embodiments above, along the first direction X, the projected area of ​​the second empty foil region 125 is S5, and the projected area of ​​the first notch 121 is S8, satisfying S8=S5.

[0232] In the above solution, the projected area of ​​the first notch 121 is equal to the projected area of ​​the second empty foil area 125 , so that the second electrode 12 can be provided with more second active material layers, and the battery cell 100 can have a higher energy density.

[0233] In some embodiments, the first electrode 11 is an anode electrode, and the second electrode 12 is a cathode electrode.

[0234] The area of ​​the first notch 121 is larger than the projected area of ​​the first empty foil region 114 .

[0235] Referring to FIG. 2 , in one or more of the above optional embodiments, the battery cell 100 further includes a diaphragm 13 , which is disposed between adjacent first and second electrode sheets 11 and 12 .

[0236] In the above solution, the provision of the diaphragm 13 can insulate and isolate the first pole piece 11 from the second pole piece 12 .

[0237] 10 , the diaphragm 13 has a third notch 131 and a fourth notch 132 . Along the first direction X, the first empty foil area 114 (see FIG. 3 ) is exposed to the third notch 131 , and the second empty foil area 125 (see FIG. 3 ) is exposed to the fourth notch 132 .

[0238] The setting of the third notch 131 can facilitate the folding of the first empty foil areas 114, so that multiple first empty foil areas 114 can be connected to the first adapter 30. The setting of the fourth notch 132 can facilitate the folding of the second empty foil areas 125, so that multiple second empty foil areas 125 can be connected to the second adapter 40.

[0239] In some embodiments, the third notch 131 is disposed at the fifth corner 13 a of the diaphragm 13 , and the fourth notch 132 is disposed at the sixth corner 13 b of the diaphragm 13 .

[0240] According to some embodiments of the present application, an electrical device is further provided, which includes a battery cell 100 provided in any of the above embodiments, and the battery cell 100 is used to provide electrical energy.

[0241] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described 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 encompasses all technical solutions within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: An electrode assembly, wherein the electrode assembly is a laminated structure, comprising a plurality of first pole pieces and a plurality of second pole pieces stacked along a first direction, wherein the first pole pieces and the second pole pieces have opposite polarities; The first electrode sheet includes a first current collector and a first active material layer. The first current collector includes a first main body region and a first hollow foil region connected to each other. The first active material layer is provided on the surface of the first main body region, and the first active material layer is not provided on the surface of the first hollow foil region. The second pole piece has a first notch, and along the first direction, the first empty foil area is exposed to the first notch; The first current collector has a first gap, which is arranged between the first empty foil area and the first main body area, so that the first empty foil area can move relative to the first main body area along the connection with the first main body area.

2. The battery cell according to claim 1, characterized in that Along the length direction and the width direction of the first pole piece, the first hollow foil area does not protrude from the first main body area.

3. The battery cell according to claim 1, characterized in that The first empty foil area is located at a first corner of the first pole piece.

4. The battery cell according to claim 1, characterized in that One end of the first slit extends to an edge of the first pole piece.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The first hollow foil area includes a first edge and a second edge adjacent to each other. The first edge is connected to the first main area, and the first gap is formed between the second edge and the first main area.

6. The battery cell according to any one of claims 1 to 4, characterized in that: The first gap extends along the length direction or the width direction of the first pole piece.

7. The battery cell according to any one of claims 1 to 4, characterized in that: At least one of the following conditions is met: (1) Along the first direction, the projected area of ​​the first empty foil area is S1, which satisfies 4mm 2 ≤S1≤50mm 2 ; (2) Along the first direction, the projected area of ​​the first empty foil area is S1, and the projected area of ​​the first gap is S2, satisfying, 4mm 2 ≤S1+S2≤51mm 2 ; (3) The width of the first gap is K1, which satisfies 0<K1≤0.1mm; (4) Along the first direction, the projected area of ​​the first main body region is S3, the length of the first pole piece is L, and the width of the first pole piece is W, satisfying S3 / (L*W)≥99%.

8. The battery cell according to any one of claims 1 to 4, characterized in that: The second electrode sheet includes a second current collector and a second active material layer, the second current collector includes a second main body area and a second hollow foil area connected to each other, the second active material layer is provided on the surface of the second main body area, and the second active material layer is not provided on the surface of the second hollow foil area; The first pole piece has a second notch, and along the first direction, the second empty foil area is exposed to the second notch; The second current collector has a second gap, which is arranged between the second hollow foil area and the second main body area, so that the second hollow foil area can move relative to the second main body area along the connection with the second main body area.

9. The battery cell according to claim 8, characterized in that The width of the first pole piece is W, the thickness of the battery cell is H, along the first direction, the projected area of ​​the first empty foil area is S1, the projected area of ​​the first gap is S2, and the projected area of ​​the second notch is S4, satisfying S1+S2+S4<3.6*W.

10. The battery cell according to claim 9, characterized in that: When H>7mm, S1+S2+S4<3.6*W.

11. The battery cell according to claim 9, characterized in that When H≤7mm, S1+S2+S4<1.6*W.

12. The battery cell according to claim 8, characterized in that Along the first direction, the projected area of ​​the second notch is S4, which satisfies the following conditions: 4mm 2 ≤S4≤50mm 2 .

13. The battery cell according to claim 8, characterized in that The battery cell also includes a packaging bag, a first adapter and a second adapter. The electrode assembly is accommodated in the packaging bag. The first adapter is electrically connected to the multiple first empty foil areas and extends out of the packaging bag. The second adapter is electrically connected to the multiple second empty foil areas and extends out of the packaging bag.

14. The battery cell according to claim 13, characterized in that: The first adapter is provided at one end of the first pole piece in the length direction. Along the length direction of the first pole piece, the minimum distance between the first main body area and the inner wall of the packaging bag is G, which satisfies G≤0.7mm.

15. The battery cell according to claim 8, characterized in that The first pole piece is an anode pole piece, the second pole piece is a cathode pole piece, and the width of the second gap is K2, satisfying K2>K1.

16. The battery cell according to claim 15, characterized in that: The width of the second gap is K2, which satisfies 0.1 mm < K2 ≤ 1 mm.

17. The battery cell according to claim 8, characterized in that The battery cell also includes a diaphragm, which is arranged between the adjacent first electrode piece and the second electrode piece. The diaphragm has a third notch and a fourth notch. Along the first direction, the first empty foil area is exposed to the third notch, and the second empty foil area is exposed to the fourth notch.

18. An electrical device, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 17, wherein the battery cell is used to provide electrical energy.

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