Battery cell, battery device, electric device, and electrode assembly

Abstract

The utility model provides a battery cell, a battery device, a power utilization device and an electrode assembly. The battery monomer comprises an electrode assembly, the electrode assembly comprises a first pole piece, the first pole piece comprises a first bending part and two first straight parts, the two first straight parts are arranged at intervals along a first direction, and the first bending part is connected with the two first straight parts; the polarity of the second pole piece is opposite to that of the first pole piece, the second pole piece comprises a second bent part and two second straight parts, the two second straight parts are arranged at intervals in the first direction, the second bent part is connected with the two second straight parts, a first straight part is arranged between the two second straight parts in the second pole piece, and the first straight part is connected with the second bent part; and a second straight part is arranged between the two first straight parts in the first pole piece. Compared with the prior art, the number of the cut end faces is effectively reduced, so that the probability of burrs is reduced, and the effect of improving the reliability of the single battery is achieved.

Description

Technical Field

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

[0002] Energy conservation and emission reduction are the keys to the sustainable development of the automotive industry. Electric vehicles have become an important part of the sustainable development of the automotive industry due to their advantages of energy conservation and environmental protection. For electric vehicles, battery technology is an important factor related to their development.

[0003] Battery devices are widely used in fields such as portable electronic devices, electric transportation vehicles, electric tools, drones, energy storage devices, etc. With the increasing demand for batteries, higher requirements are put forward for the reliability of battery cells. Therefore, how to improve the reliability of battery cells is an urgent problem to be solved in battery technology. Summary of the Utility Model

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

[0005] In a first aspect, an embodiment of the present application provides a battery cell, including an electrode assembly. The electrode assembly includes a first pole piece, which includes a first bending portion and two first straight portions. The two first straight portions are arranged at intervals along a first direction, and the first bending portion connects the two first straight portions. A second pole piece, having a polarity opposite to that of the first pole piece, the second pole piece includes a second bending portion and two second straight portions. The two second straight portions are arranged at intervals along the first direction, and the second bending portion connects the two second straight portions. One first straight portion is arranged between the two second straight portions of the second pole piece, and one second straight portion is arranged between the two first straight portions of the first pole piece.

[0006] In the above technical solution, since the first bending portion is respectively connected to the two first straight portions, the cutting end surface at one end where the first straight portion is connected to the first bending portion is cancelled, thereby reducing the probability of burrs appearing on the first pole piece. At the same time, since the second bending portion is respectively connected to the two second straight portions, the cutting end surface at one end where the second straight portion is connected to the second bending portion is cancelled, thereby reducing the probability of burrs appearing on the second pole piece. Therefore, due to the reduction of the probability of burrs appearing, the risk of short circuit between the first pole piece and the second pole piece is reduced. Secondly, through the above design of the positions between the first pole piece and the second pole piece, the electrode assembly forms a stable structure, thereby improving the stability of the structure of the battery cell after stacking. Such a battery cell structure reduces the risk of short circuit between the first pole piece and the second pole piece on the one hand; on the other hand, it improves the stability of the structure of the battery cell after stacking. Thus, the technical effect of improving the reliability of the battery cell is achieved.

[0007] In some embodiments, the first bent portion is connected to one end of the first straight portion along the second direction. Along the second direction, a first insulating layer is provided at one end of the first straight portion away from the first bent portion, and the second direction is perpendicular to the first direction.

[0008] In the above technical solution, by providing the first insulating layer, the end face of the first straight portion can be effectively covered, thereby reducing the risk of short circuit between the first electrode plate and the second electrode plate.

[0009] In some embodiments, the first insulating layer includes a first insulating portion, a second insulating portion, and a third insulating portion connected in sequence. Along the second direction, the second insulating portion covers at least a part of the end face of one end of the first straight portion away from the first bent portion. Along the first direction, at least a part of the first insulating portion is provided on one side of the first straight portion, and at least a part of the third insulating portion is provided on the other side of the first straight portion.

[0010] In the above technical solution, by providing that the first insulating layer is composed of a first insulating portion, a second insulating portion, and a third insulating portion, the connection between the first insulating layer and the end of the first straight portion is firm, reducing the possibility of the first insulating layer falling off.

[0011] In some embodiments, the thickness of the first insulating layer is T1, the thickness of the first straight portion is T2, and the thickness of the second straight portion is T3, satisfying T1≤T2 and T1≤T3.

[0012] In the above technical solution, by setting T1≤T2 and T1≤T3, the thickness of the first insulating layer is within a suitable dimension range, so that on the one hand, the risk of lithium deposition due to too large a gap between the first electrode plate and the second electrode plate after the battery cells are stacked can be reduced; on the other hand, the risk of short circuit between the first electrode plate and the second electrode plate caused by burrs easily piercing the first insulating layer can be reduced.

[0013] In some embodiments, in a cross-section perpendicular to the third direction, the dimension of the first insulating layer in its extending direction is W1, and along the first direction, the thickness of the first straight portion is T2, satisfying 0mm≤W1 - 2×T2≤10mm, and the first direction, the second direction, and the third direction are perpendicular to each other pairwise.

[0014] In the above technical solution, by setting 0mm≤W1 - 2×T2≤10mm, the possibility of the first insulating layer falling off is reduced.

[0015] In some embodiments, along the third direction, the length of the first insulating layer is L1, and the length of the first straight portion is L2, satisfying L1≥L2, and the first direction, the second direction, and the third direction are perpendicular to each other pairwise.

[0016] In the above technical solution, by setting L1≥L2, the length of the first insulating layer in the third direction is greater than or equal to the length of the first flat portion in the third direction, so that in the third direction, it is beneficial for the first insulating layer to cover a larger area of the end of the first flat portion away from the first bending portion, thereby reducing the risk of short circuit between the first pole piece and the second pole piece.

[0017] In some embodiments, in the third direction, the length of the second flat portion is L5, satisfying L5>L2 and L1≥L5.

[0018] In the above technical solution, by setting L5>L2 and L1≥L5, in the third direction, a part of the first insulating layer can extend beyond the second flat portion, and the extended part can support the local area where the second flat portion extends beyond after the battery cells are stacked, thereby reducing local stress concentration in this part.

[0019] In some embodiments, the second bending portion is connected to one end of the second flat portion in the second direction. In the second direction, a second insulating layer is provided at the end of the second flat portion away from the second bending portion, and the second direction is perpendicular to the first direction.

[0020] In the above technical solution, the second insulating layer can effectively cover the end face of the second flat portion, thereby reducing the risk of short circuit between the first pole piece and the second pole piece.

[0021] In some embodiments, a third insulating layer is provided on the side of the first bending portion facing the second flat portion.

[0022] In the above technical solution, by providing a third insulating layer on the side of the first bending portion facing the second flat portion, the side of the first bending portion facing the second flat portion has insulating properties, thereby reducing the risk of short circuit between the first pole piece and the second pole piece.

[0023] In some embodiments, the first bending portion includes a first current collector portion, and the third insulating layer is provided on the surface of the first current collector portion facing the second flat portion; or the first bending portion includes a first current collector portion and a first active material portion, the first active material portion is provided on the surface of the first current collector portion facing the second flat portion, and the third insulating layer is provided on the surface of the first active material portion facing the second flat portion.

[0024] In the above technical solution, by providing a third insulating layer on the side of the first current collector facing the second flat portion or on the side of the first active material portion facing the second flat portion, the side of the first current collector facing the second flat portion or the side of the first active material portion facing the second flat portion has insulating properties, thereby reducing the risk of short circuit between the first electrode and the second electrode.

[0025] In some embodiments, a fourth insulating layer is provided on the side of the first bent portion facing away from the second flat portion.

[0026] In the above technical solution, by providing a fourth insulating layer on the side of the first bent portion facing away from the second flat portion, the side of the first bent portion facing away from the second flat portion has insulating properties, thereby reducing the risk of short circuit between the first electrode and the second electrode.

[0027] In some embodiments, the first bent portion is connected to one end of the first flat portion along the second direction. In a cross-section perpendicular to the third direction, the dimension of the fourth insulating layer in its extending direction is W2, the thickness of the first flat portion along the first direction is T2, and the dimension of the second flat portion is T3, satisfying 0 mm ≤ W2 - (2 × T2 + T3) ≤ 10 mm, where the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0028] In the above technical solution, by setting 0 mm ≤ W2 - (2 × T2 + T3) ≤ 10 mm, after the battery cells are stacked, it is beneficial for the fourth insulating layer to better cover one end of the second flat portion away from the second bent portion, thereby reducing the risk of short circuit between the first electrode and the second electrode.

[0029] In some embodiments, the thicknesses of the third insulating layer and the fourth insulating layer are both T4, the thickness of the first flat portion is T2, and the thickness of the second flat portion is T3, satisfying T4 ≤ T2 and T4 ≤ T3.

[0030] In the above technical solution, by setting T4 ≤ T2 and T4 ≤ T3, the thicknesses of the third insulating layer and the fourth insulating layer are within a suitable dimension range, so that on the one hand, the risk of lithium deposition due to excessive gap between the first electrode and the second electrode after the battery cells are stacked is reduced; on the other hand, the risk of short circuit between the first electrode and the second electrode caused by burrs easily piercing the first insulating layer is reduced.

[0031] In some embodiments, the first bent portion is connected to one end of the first flat portion along the second direction. Along the third direction, the lengths of the third insulating layer and the fourth insulating layer are both L4, and the length of the first flat portion is L2, satisfying L4 ≥ L2, where the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0032] In the above technical solution, by setting L4≥L2, the third insulating layer or the fourth insulating layer can cover a larger area of the end of the first straight portion away from the first bent portion along the third direction, thereby reducing the risk of short circuit between the first pole piece and the second pole piece.

[0033] In some embodiments, along the third direction, the length of the second straight portion is L5, satisfying L5>L2, and L4≥L5.

[0034] In the above technical solution, by setting L5>L2 and L4≥L5, a partial area of the third insulating layer or the fourth insulating layer can extend beyond the second straight portion in the third direction. The extended portion can support the local area extending beyond the second straight portion after the battery cells are stacked, thereby reducing local stress concentration in this part.

[0035] In some embodiments, a fifth insulating layer is provided on a side of the second bent portion facing the first straight portion.

[0036] In the above technical solution, by providing a fifth insulating layer on the side of the second bent portion facing the first straight portion, the side of the second bent portion facing the first straight portion has insulating properties, thereby reducing the risk of short circuit between the first pole piece and the second pole piece.

[0037] In some embodiments, a sixth insulating layer is provided on a side of the second bent portion facing away from the first straight portion.

[0038] In the above technical solution, by providing a sixth insulating layer on the side of the second bent portion away from the first straight portion, the side of the second bent portion away from the first straight portion has insulating properties, thereby reducing the risk of short circuit between the first pole piece and the second pole piece.

[0039] In some embodiments, the first bent portion is connected to one end of the first straight portion along the second direction, the first pole piece includes a first pole lug, and each first straight portion is provided with a first pole lug at one end along the third direction, and in a projection plane perpendicular to the first direction, the orthographic projections of the first pole lugs on two first straight portions in the first pole piece at least partially overlap; and / or the second bent portion is connected to one end of the second straight portion along the second direction, the second pole piece includes a second pole lug, and each second straight portion is provided with a second pole lug at one end along the third direction, and in a projection plane perpendicular to the first direction, the orthographic projections of the second pole lugs on two second straight portions in the second pole piece at least partially overlap; the first direction, the second direction and the third direction are perpendicular to each other.

[0040] In the above technical solution, by setting the orthographic projections of the first pole ears on the two first straight portions to at least partially overlap, the mutual connection between the first pole ears is facilitated, and by setting the orthographic projections of the second pole ears on the two second straight portions to at least partially overlap, the mutual connection between the second pole ears is facilitated.

[0041] In some embodiments, the first bending portion includes a first collecting portion, and the first collecting portion is provided with a first reinforcement portion; and / or the second bending portion includes a second collecting portion, and the second collecting portion is provided with a second reinforcement portion.

[0042] In the above technical solution, the first reinforcing portion is provided to increase the strength of the first bent portion, thereby reducing the occurrence of wrinkles and other undesirable phenomena on the first bent portion when the battery cells are stacked. The second reinforcing portion is provided to increase the strength of the second bent portion, thereby reducing the occurrence of wrinkles and other undesirable phenomena on the second bent portion when the battery cells are stacked.

[0043] In some embodiments, the first bending portion is connected to one end of the first straight portion along the second direction, the second bending portion is connected to one end of the second straight portion along the second direction away from the first bending portion, and the second direction is perpendicular to the first direction.

[0044] In the above technical solution, the first bending portion and the second bending portion are arranged at intervals, so that after the battery cells are stacked, the arrangement of the first pole piece and the second pole piece is more reasonable.

[0045] In some embodiments, there are multiple first pole pieces and multiple second pole pieces, and along the first direction, the first straight portions and the second straight portions are alternately arranged.

[0046] In the above technical solution, by alternately arranging the plurality of first straight portions and the plurality of second straight portions, the arrangement of the first pole pieces and the second pole pieces is more reasonable after the battery cells are stacked.

[0047] In some embodiments, the first electrode sheet includes a first current collector and a first active material layer, the first active material layer is arranged on the surface of the first current collector, the portion of the first current collector located at the first bend portion is the first current collecting portion, the portion of the first current collector located at the first straight portion is the third current collecting portion, and the first current collecting portion and the third current collecting portion are integrally formed; and / or, the second electrode sheet includes a second current collector and a second active material layer, the second active material layer is arranged on the surface of the second current collector, the portion of the second current collector located at the second bend portion is the second current collecting portion, the portion of the second current collector located at the second straight portion is the fourth current collecting portion, and the second current collecting portion and the fourth current collecting portion are integrally formed.

[0048] In the above technical solution, by providing that the first current collector includes a first current collecting portion and a third current collecting portion, and the first current collecting portion and the third current collecting portion are integrally formed, it is convenient for the processing and forming of the first electrode sheet. By providing that the second current collector includes a second current collecting portion and a fourth current collecting portion, and the second current collecting portion and the fourth current collecting portion are integrally formed, it is convenient for the processing and forming of the second electrode sheet.

[0049] In a second aspect, an embodiment of the present application provides a battery device, including the battery cell provided in any one of the embodiments of the first aspect.

[0050] In a third aspect, an embodiment of the present application provides an electrical device, including the battery cell provided in any one of the embodiments of the first aspect.

[0051] In a fourth aspect, an embodiment of the present application provides an electrode assembly, including a first electrode sheet, which includes a first bending portion and two first straight portions. The two first straight portions are arranged at intervals along a first direction, and the first bending portion connects the two first straight portions; a second electrode sheet, the second electrode sheet has a polarity opposite to that of the first electrode sheet, the second electrode sheet includes a second bending portion and two second straight portions, the two second straight portions are arranged at intervals along the first direction, the second bending portion connects the two second straight portions, a first straight portion is arranged between the two second straight portions of the second electrode sheet, and a second straight portion is arranged between the two first straight portions of the first electrode sheet.

[0052] In some embodiments, the first bending portion is connected to one end of the first straight portion along a second direction. Along the second direction, a first insulating layer is provided at one end of the first straight portion away from the first bending portion, and the second direction is perpendicular to the first direction.

[0053] In some embodiments, a third insulating layer is provided on a side of the first bending portion facing the second straight portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0055] Figure 1 It is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0056] Figure 2 It is an exploded view of a battery device provided in some embodiments of the present application;

[0057] Figure 3 It is an exploded view of a battery cell provided in some embodiments of the present application;

[0058] Figure 4 Schematic structural diagram of the electrode assembly provided for some embodiments of the present application;

[0059] Figure 5 Schematic structural diagram of the electrode assembly provided for some embodiments of the present application (showing the first insulating layer);

[0060] Figure 6 Schematic structural diagram of the electrode assembly provided for some other embodiments of the present application (showing the first insulating layer);

[0061] Figure 7 is Figure 6 Partial enlarged schematic diagram at position A in

[0062] Figure 8 is Figure 5 View B of the electrode assembly shown;

[0063] Figure 9 Schematic structural diagram of the electrode assembly provided for some embodiments of the present application (showing the first insulating layer and the second insulating layer);

[0064] Figure 10 is Figure 9 Partial enlarged schematic diagram at position C in

[0065] Figure 11 is Figure 9 View D of the electrode assembly shown;

[0066] Figure 12 Schematic structural diagram of the electrode assembly provided for some embodiments of the present application (showing the third insulating layer);

[0067] Figure 13 Schematic structural diagram of the electrode assembly provided for some other embodiments of the present application (showing the third insulating layer);

[0068] Figure 14 Schematic structural diagram of the electrode assembly provided for some embodiments of the present application (showing the third insulating layer and the fourth insulating layer);

[0069] Figure 15 is Figure 14 Partial enlarged schematic diagram at position E in

[0070] Figure 16 is Figure 14 View F of the electrode assembly shown;

[0071] Figure 17 Schematic structural diagram of the electrode assembly provided for some embodiments of the present application (showing the third insulating layer, the fourth insulating layer, the fifth insulating layer and the sixth insulating layer);

[0072] Figure 18 Schematic structural diagram of the first electrode tab provided in some embodiments of the present application;

[0073] Figure 19 Schematic structural diagram of the second electrode tab provided in some embodiments of the present application;

[0074] Figure 20 Schematic structural diagram of the electrode assembly provided in some embodiments of the present application (showing the first reinforcing part and the second reinforcing part);

[0075] Figure 21 Schematic structural diagram of the electrode assembly provided in other embodiments of the present application (showing the first reinforcing part and the second reinforcing part);

[0076] Figure 22 Electrode assembly provided in some embodiments of the present application (showing the first electrode tab, the second electrode tab, and the third electrode tab).

[0077] Icon:

[0078] 1000 - Vehicle;

[0079] 100 - Battery device; 200 - Controller; 300 - Motor;

[0080] 10 - Battery cell; 1 - Housing; 11 - Shell; 12 - End cap; 2 - Electrode assembly; 21 - First electrode tab; 211 - First flat part; 2111 - First end face; 212 - First bent part; 213 - First current collector; 2131 - First current collecting part; 2132 - Third current collecting part; 214 - First active material layer; 2141 - First active material part; 22 - First insulating layer; 221 - First insulating part; 222 - Second insulating part; 223 - Third insulating part; 23 - Third insulating layer; 24 - Fourth insulating layer; 25 - First tab; 26 - Second electrode tab; 261 - Second flat part; 2611 - Second end face; 262 - Second bent part; 263 - Second current collector; 2631 - Second current collecting part; 2632 - Fourth current collecting part; 264 - Second active material layer; 27 - Second insulating layer; 271 - Fourth insulating part; 272 - Fifth insulating part; 273 - Sixth insulating part; 28 - Fifth insulating layer; 29 - Sixth insulating layer; 30 - Second tab; 31 - First reinforcing part; 32 - Second reinforcing part; 33 - Third electrode tab; 3 - Electrode terminal;

[0081] 20 - Box body; 201 - First box body; 202 - Second box body;

[0082] X - First direction; Y - Second direction; Z - Third direction. Detailed implementation manners

[0083] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0084] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in the description of this application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "include" and "have" and any variations thereof in the description and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above drawings are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship.

[0085] Referring to "embodiments" in this application means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0086] In the description of this application, it should be noted that unless otherwise clearly specified and limited, the terms "install", "connect", "attach" 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 directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0087] The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that three relationships can 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 represents an "or" relationship between the associated objects before and after.

[0088] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thicknesses, lengths, widths, etc. of various components in the embodiments of this application shown in the drawings, as well as the overall thickness, length, width, etc. of the integrated device, are only for illustrative purposes and should not constitute any limitation to this application.

[0089] In this application, "a plurality of" means two or more (including two).

[0090] In the embodiments of this application, the battery cell may be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to be used.

[0091] The battery cell includes, but is not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0092] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) intercalate and deintercalate back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive and negative electrodes and allow active ions to pass through.

[0093] In some embodiments, the positive electrode may be a positive electrode tab, and the positive electrode tab may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0094] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0095] As an example, the positive electrode current collector may be a foil or a composite current collector. For example, as a foil, aluminum with silver plating on the surface, stainless steel with silver plating on the surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0096] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery monomer can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, etc. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and their modified compounds, etc.

[0097] In some embodiments, the positive electrode may use a foam metal. The foam metal may be foam nickel, foam copper, foam aluminum, foam alloy, etc. When the foam metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foam metal, and of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foam metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0098] In some embodiments, the negative electrode may be a negative electrode tab, and the negative electrode tab may include a negative current collector.

[0099] As an example, the negative current collector may be a foil, a foam metal, or a composite current collector. For example, as a foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, copper, aluminum, nickel, carbon electrodes, carbon, or titanium, etc. may be used. The foam metal may be foam nickel, foam copper, foam aluminum, foam alloy, etc. The composite current collector may include a polymer material substrate layer and a metal layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0100] As an example, the negative electrode tab may include a negative current collector and a negative active material provided on at least one surface of the negative current collector.

[0101] As an example, the negative current collector has two surfaces opposite to each other in its own thickness direction, and the negative active material is provided on either one or both of the two opposite surfaces of the negative current collector.

[0102] As an example, the negative active material may be a negative active material for battery cells known in the art. As an example, the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative active material of battery cells may also be used. These negative active materials may be used alone or in combination of two or more.

[0103] In some embodiments, the material of the positive current collector may be aluminum, and the material of the negative current collector may be copper.

[0104] In some embodiments, the separator is a separator membrane. The separator membrane may be any known porous structure separator membrane with good chemical stability and mechanical stability.

[0105] As an example, the material of the separator membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane may be a single-layer film or a multi-layer composite film. When the separator membrane is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a single component located between the positive and negative electrodes, or may be attached to the surfaces of the positive and negative electrodes.

[0106] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive electrode and the negative electrode, and functions to transport ions and isolate the positive and negative electrodes simultaneously.

[0107] In some embodiments, the battery cell further includes an electrolyte, which functions to conduct ions between the positive and negative electrodes. The electrolyte can be liquid, gel or solid. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0108] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0109] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

[0110] Among them, the gel electrolyte includes a polymer as the skeleton network of the electrolyte, combined with an ionic liquid-lithium salt.

[0111] Among them, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0112] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, single-ion polymer, poly(ionic liquid)-lithium salt, cellulose, etc.

[0113] As an example, the inorganic solid electrolyte may include one or more of oxide solid electrolytes (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), sulfide solid electrolytes (crystalline lithium superionic conductor (lithium germanium phosphorus sulfur, argyrodite), amorphous sulfide), and halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0114] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0115] In some embodiments, the electrode assembly has a laminated structure.

[0116] As an example, a plurality of separators may be provided and are respectively disposed between any adjacent positive electrode plates or negative electrode plates.

[0117] As an example, the separators may be continuously provided and are disposed between any adjacent positive electrode plates or negative electrode plates by folding or winding.

[0118] In some embodiments, the shape of the electrode assembly may be cylindrical, flat, prismatic, or the like.

[0119] In some embodiments, the electrode assembly is provided with tabs, and the tabs can conduct current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0120] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum plastic film, etc.

[0121] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell, or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a multi-prismatic battery cell, and the multi-prismatic battery cell is, for example, a hexagonal-prismatic battery cell, etc.

[0122] The battery device mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include a plurality of battery cells, and the plurality of battery cells are connected in series, parallel, or in a hybrid connection through a busbar component.

[0123] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells; as an example, the battery cell assembly can be a battery module, and the battery module is formed by arranging and fixing a plurality of battery cells to form an independent module.

[0124] As an example, the battery module can be formed by bundling a plurality of battery cells with cable ties.

[0125] In some embodiments, the battery device can be a battery pack, and the battery pack can include a box body and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box body.

[0126] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the box body by fixing the battery module in the box body.

[0127] As an example, the battery cell assembly can also be accommodated in the box by directly fixing a plurality of battery cells to the box.

[0128] As an example, the box can include a first box and a second box. The first box and the second box are snapped together so that a closed space is formed inside the box to accommodate the battery cell assembly. Here, "closed" means covering or closing, which can be sealed or non-sealed. The first box can be a top cover or a bottom plate.

[0129] As an example, the box can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame so that a closed space is formed inside the box to accommodate the battery cell assembly.

[0130] As an example, the box can be part of the chassis structure of a vehicle. For example, the top cover of the box can become at least part of the floor of the vehicle, or the frame of the box can become at least part of the cross beams and longitudinal beams of the vehicle.

[0131] In some embodiments, the battery device refers to an energy storage device, and the energy storage device includes a box, and at least one side of the box is provided with a door. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0132] Currently, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in many fields such as military equipment and aerospace. With the continuous expansion of the application fields of power batteries, the market demand for them is also continuously increasing.

[0133] To solve the technical problem of improving the energy density of a single battery cell to meet market demands, an electrode assembly with a laminated structure is generally used. The electrode assembly with a laminated structure is formed by alternately stacking a plurality of positive electrode plates and a plurality of negative electrode plates. However, before stacking the above structure, it is necessary to cut to form a plurality of positive electrode plates and a plurality of negative electrode plates. This will result in at least two cut end faces for each positive electrode plate and at least two cut end faces for each negative electrode plate. Furthermore, when the number of stacked layers of the electrode assembly increases, the number of cut end faces will also increase accordingly. For example, when an electrode assembly with an eight-layer structure needs to be stacked (alternately stacking four positive electrode plates and four negative electrode plates), it is necessary to first cut a whole positive electrode plate into four positive electrode plates and cut a whole negative electrode plate into four negative electrode plates. At this time, the four positive electrode plates will form at least eight cut end faces, and the four negative electrode plates will form at least eight cut end faces, resulting in multiple cut end faces after stacking. At the same time, due to the interaction between the cutting tool and the electrode plate, metal micro-protrusions, that is, burrs, will be generated on the cut end faces of the electrode plate. Therefore, in the prior art, the probability of burrs appearing increases due to the increase in the number of cut end faces, thereby increasing the short-circuit probability between the electrode plates and affecting the reliability of the single battery cell.

[0134] Based on the above considerations, to solve the problem that the reliability of the single battery cell is reduced due to the increase in the number of cut end faces, which increases the probability of burrs appearing, an embodiment of the present application provides a single battery cell, including an electrode assembly. The electrode assembly includes a first electrode plate, including a first bending portion and two first straight portions, the two first straight portions are arranged at intervals along a first direction, and the first bending portion connects the two first straight portions; a second electrode plate, having the opposite polarity to the first electrode plate, the second electrode plate includes a second bending portion and two second straight portions, the two second straight portions are arranged at intervals along the first direction, the second bending portion connects the two second straight portions, and a first straight portion is arranged between the two second straight portions of the second electrode plate, and a second straight portion is arranged between the two first straight portions of the first electrode plate.

[0135] In such a battery cell, first, a first electrode tab is provided to include a first bent portion and two first straight portions. The first bent portion connects the two first straight portions. Since the first bent portion is respectively connected to the two first straight portions, the cut end surface at one end where the first straight portion is connected to the first bent portion is eliminated, thereby reducing the probability of burrs appearing on the first electrode tab. At the same time, a second electrode tab is provided to include a second bent portion and two second straight portions. The second bent portion connects the two second straight portions. Since the second bent portion is respectively connected to the two second straight portions, the cut end surface at one end where the second straight portion is connected to the second bent portion is eliminated, thereby reducing the probability of burrs appearing on the second electrode tab. Therefore, due to the reduction in the probability of burrs appearing on the first electrode tab and the second electrode tab, the risk of short circuit between the first electrode tab and the second electrode tab is reduced. Secondly, the two first straight portions are arranged at intervals along a first direction, and the two second straight portions are arranged at intervals along the first direction. One first straight portion is arranged between the two second straight portions of the second electrode tab, and one second straight portion is arranged between the two first straight portions of the first electrode tab. Thus, through the above design of the positions between the first electrode tab and the second electrode tab, the electrode assembly forms a stable structure, thereby improving the stability of the battery cell structure after stacking. Such a battery cell structure reduces the risk of short circuit between the first electrode tab and the second electrode tab on the one hand; on the other hand, it improves the stability of the battery cell structure after stacking. Thus, the technical effect of improving the reliability of the battery cell is achieved.

[0136] The technical solutions described in the embodiments of the present application are applicable to various electrical devices using battery cells and battery devices, such as mobile phones, portable devices, laptop computers, battery cars, electric toys, electric tools, vehicles, ships, and spacecrafts, etc. For example, spacecrafts include airplanes, rockets, space shuttles, and spaceships, etc.

[0137] For the convenience of description in the following embodiments, the electrical device is taken as an example of a vehicle.

[0138] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application. A battery device 100 is provided inside the vehicle 1000, and the battery device 100 can be arranged at the bottom, head, or tail of the vehicle 1000. The battery device 100 can be used for power supply of the vehicle 1000. For example, the battery device 100 can be used as the operating power source of the vehicle 1000.

[0139] The vehicle 1000 may further include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300. For example, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1000.

[0140] In some embodiments of the present application, the battery device 100 can not only serve as the operating power source of the vehicle 1000, but also as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0141] Please refer to Figure 2 , Figure 2 which is an exploded view of the battery device provided in some embodiments of the present application. The battery device 100 may include battery cells 10 and a box body 20, and the box body 20 is used to accommodate the battery cells 10.

[0142] Among them, a closed space for accommodating the battery cells 10 is formed inside the box body 20, and the box body 20 can adopt various structures. In some embodiments, the box body 20 may include a first box body 201 and a second box body 202, and the first box body 201 and the second box body 202 are buckled with each other. The first box body 201 and the second box body 202 can be of various shapes, such as a cuboid, a cylinder, etc. The first box body 201 may be a hollow structure with one side open, and the second box body 202 may also be a hollow structure with one side open. The open side of the second box body 202 and the open side of the first box body 201 are buckled with each other, thus forming the box body 20 with a closed space. It can also be that the first box body 201 is a hollow structure with one side open, and the second box body 202 is a plate-like structure. The second box body 202 is buckled to the open side of the first box body 201, thus forming the box body 20 with a closed space.

[0143] In the battery device 100, the battery cells 10 can be one or multiple. If there are multiple battery cells 10, the multiple battery cells 10 can be connected in series, parallel or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells 10. It can be that multiple battery cells 10 are first connected in series, parallel or in a mixed connection to form a battery module, and then multiple battery modules are connected in series, parallel or in a mixed connection to form a whole and are accommodated in the box body 20. It can also be that all the battery cells 10 are directly connected in series, parallel or in a mixed connection together, and then the whole formed by all the battery cells 10 is accommodated in the box body 20.

[0144] In some embodiments, the battery device 100 may further include a busbar component. The multiple battery cells 10 can be electrically connected through the busbar component to achieve series, parallel or mixed connection of the multiple battery cells 10. The busbar component can be a metal conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0145] Please refer to Figure 3 , Figure 3 which is an exploded view of the battery cell provided in some embodiments of the present application. The battery cell 10 may include a housing 1 and an electrode assembly 2, and the electrode assembly 2 is accommodated in the housing 1.

[0146] In some embodiments, the outer shell 1 may include a housing 11 and an end cap 12. The housing 11 has an opening, and the end cap 12 closes the opening of the housing 11. Here, "closing" means covering or shutting, which can be a seal or non-seal.

[0147] The housing 11 is a component for accommodating the electrode assembly 2. The housing 11 can be a hollow structure with an opening formed at one end, or a hollow structure with openings formed at opposite ends. The housing 11 can be of various shapes, such as cylindrical, cuboid, etc. The material of the housing 11 can be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. The electrode assembly 2 can be partially located inside the housing 11 or entirely located inside the housing 11.

[0148] The end cap 12 and the housing 11 together define a receiving space for accommodating the electrode assembly 2 and other components. The end cap 12 can be connected to the housing 11 by means of welding, crimping, etc. to close the opening of the housing 11. The shape of the end cap 12 can be adapted to the shape of the housing 11. For example, when the housing 11 is a cuboid structure, the end cap 12 is a rectangular plate-like structure adapted to the housing 11. Another example is that when the housing 11 is a cylindrical structure, the end cap 12 is a circular plate-like structure adapted to the housing 11. The material of the end cap 12 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of the end cap 12 and the housing 11 can be the same or different.

[0149] In an embodiment where the housing 11 has an opening formed at one end, one end cap 12 can be correspondingly provided. In an embodiment where the housing 11 has openings formed at opposite ends, two end caps 12 can be correspondingly provided. The two end caps 12 respectively close the two openings of the housing 11, and the two end caps 12 and the housing 11 together define the receiving space.

[0150] In some embodiments, the battery cell 10 may further include an electrode terminal 3. The electrode terminal 3 is disposed on the outer shell 1 and is used for electrically connecting to the tab of the electrode assembly 2 to input or output the electrical energy of the battery cell 10. The electrode terminal 3 can be disposed on the housing 11 of the outer shell 1 or on the end cap 12 of the outer shell 1. The electrode terminal 3 and the tab can be directly connected. For example, the electrode terminal 3 is welded to the tab. The electrode terminal 3 and the tab can also be indirectly connected. For example, the electrode terminal 3 and the tab are indirectly connected through a current collector member. The current collector member can be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0151] In Figure 3In the illustrated embodiment, the electrode assembly 2 has a laminated structure, and multiple electrode plates in the electrode assembly 2 are stacked along the first direction X. The tabs of the electrode assembly 2 include a positive tab and a negative tab. One end of the housing 11 forms an opening along the third direction Z, and there is one end cap 12 in the outer shell 1, and the end cap 12 closes the opening of the housing 11. There are two electrode terminals 3, and both of the two electrode terminals 3 are arranged on the end cap 12. The two electrode terminals 3 are spaced apart along the second direction Y, and the two electrode terminals 3 are electrically connected to the positive tab and the negative tab respectively. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs.

[0152] Please refer to Figure 4 , Figure 4 FIG. is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application. Some embodiments of the present application provide a battery cell 10, which includes an electrode assembly 2. The electrode assembly 2 includes a first electrode plate 21. The first electrode plate 21 includes a first bent portion 212 and two first straight portions 211. The two first straight portions 211 are spaced apart along the first direction X, and the first bent portion 212 connects the two first straight portions 211; a second electrode plate 26, having a polarity opposite to that of the first electrode plate 21. The second electrode plate 26 includes a second bent portion 262 and two second straight portions 261. The two second straight portions 261 are spaced apart along the first direction X, and the second bent portion 262 connects the two second straight portions 261. One first straight portion 211 is provided between the two second straight portions 261 of the second electrode plate 26, and one second straight portion 261 is provided between the two first straight portions 211 of the first electrode plate 21.

[0153] The battery cell 10 may further include an outer shell 1, and the electrode assembly 2 is accommodated in the outer shell 1.

[0154] The first electrode plate 21 may include a first current collector 213 and a first active material layer 214, and the first active material layer 214 may be provided on both opposite surfaces of the first current collector 213.

[0155] The first bent portion 212 may be connected to one end of the first straight portion 211 along the second direction Y. The first straight portion 211 is the straight portion of the first electrode plate 21, and the first straight portion 211 may be perpendicular to the first direction X. The first bent portion 212 is the bent portion of the first electrode plate 21. In a cross-section perpendicular to the third direction Z, the extension trajectory of the first bent portion 212 is an arc. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs. The part of the first current collector 213 located on the first straight portion 211 and the part of the first current collector 213 located on the first straight portion 211 may be integrally formed.

[0156] The two first straight portions 211 are arranged at intervals in the first direction X. It is possible that the two first straight portions 211 are arranged opposite to each other and there is a gap between the two first straight portions 211. When observed along the third direction Z, the first pole piece 21 has a U-shaped structure.

[0157] The second pole piece 26 may include a second current collector 263 and a second active material layer 264. The second active material layer 264 may be provided on both opposite surfaces of the second current collector 263.

[0158] The second bent portion 262 may be connected to one end of the second straight portion 261 in the second direction Y. The second straight portion 261 is the straight portion of the second pole piece 26, and the second straight portion 261 may be perpendicular to the first direction X. The second bent portion 262 is the bent portion of the second pole piece 26. In a cross-section perpendicular to the third direction Z, the second bent portion 262 may extend along an arc-shaped trajectory. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs. The portion of the second current collector 263 located in the second straight portion 261 and the portion of the second current collector 263 located in the second bent portion 262 may be integrally formed.

[0159] The two second straight portions 261 are arranged at intervals in the first direction X. It is possible that the two second straight portions 261 are arranged opposite to each other and there is a gap between the two second straight portions 261. When observed along the third direction Z, the second pole piece 26 has a U-shaped structure.

[0160] The polarities of the first pole piece 21 and the second pole piece 26 are opposite. It is possible that the first pole piece 21 is a positive pole piece, the first active material layer 214 is a positive electrode active material, the second pole piece 26 is a negative pole piece, and the second active material layer 264 is a negative electrode active material; or it is possible that the first pole piece 21 is a negative pole piece, the second pole piece 26 is a positive pole piece, the first active material layer 214 is a negative electrode active material, and the second active material layer 264 is a positive electrode active material. The first pole piece 21 may be one or more; the second pole piece 26 may be one or more. When both the first pole piece 21 and the second pole piece 26 are multiple, one first pole piece 21 and one second pole piece 26 stacked together may form a stacking unit, and multiple stacking units stacked together form the electrode assembly 2.

[0161] The electrode assembly 2 may further include a separator. At least a part of the separator is disposed between the first straight portion 211 and the second straight portion 261 to separate the first straight portion 211 and the second straight portion 261.

[0162] The first bending portion 212 and the second bending portion 262 may be in the same direction or in different directions. It is possible that both the first bending portion 212 and the second bending portion 262 are in the second direction Y, that is, the first bending portion 212 is provided at one end of the first straight portion 211 along the second direction Y, and the second bending portion 262 is provided at one end of the second straight portion 261 along the second direction Y; it is also possible that one of the first bending portion 212 and the second bending portion 262 is in the second direction Y and the other is in the third direction Z. Taking the first bending portion 212 in the second direction Y and the second bending portion 262 in the third direction Z as an example, that is, the first bending portion 212 is provided at one end of the first straight portion 211 along the second direction Y, and the second bending portion 262 is provided at one end of the second straight portion 261 along the third direction Z.

[0163] A first straight portion 211 is provided between two second straight portions 261 of the second pole piece 26, and a second straight portion 261 is provided between two first straight portions 211 of the first pole piece 21. It is possible that a part of the first straight portion 211 is between two second straight portions 261 or the whole of the first straight portion 211 is between two second straight portions 261, or a part of the second straight portion 261 is between two first straight portions 211 or the whole of the second straight portion 261 is between two first straight portions 211.

[0164] The two first straight portions 211 and the two second straight portions 261 may be alternately stacked.

[0165] In this embodiment, first, the first electrode tab 21 is provided to include a first bending portion 212 and two first straight portions 211. The first bending portion 212 connects the two first straight portions 211. Since the first bending portion 212 is respectively connected to the two first straight portions 211, the cutting end face at the end where the first straight portion 211 is connected to the first bending portion 212 is eliminated, thereby reducing the probability of burrs appearing on the first electrode tab 21. At the same time, the second electrode tab 26 is provided to include a second bending portion 262 and two second straight portions 261. The second bending portion 262 connects the two second straight portions 261. Since the second bending portion 262 is respectively connected to the two second straight portions 261, the cutting end face at the end where the second straight portion 261 is connected to the second bending portion 262 is eliminated, thereby reducing the probability of burrs appearing on the second electrode tab 26. Therefore, due to the reduction in the probability of burrs appearing on the first electrode tab 21 and the second electrode tab 26, the risk of short circuit between the first electrode tab 21 and the second electrode tab 26 is reduced. Secondly, the two first straight portions 211 are arranged at intervals along the first direction X, and the two second straight portions 261 are arranged at intervals along the first direction X. One first straight portion 211 is arranged between the two second straight portions 261 of the second electrode tab 26, and one second straight portion 261 is arranged between the two first straight portions 211 of the first electrode tab 21. Thus, through the above design of the positions between the first electrode tab 21 and the second electrode tab 26, the electrode assembly 2 forms a stable structure, thereby improving the stability of the structure of the battery cell 10 after stacking.

[0166] In summary, such a structure of the battery cell 10 reduces the risk of short circuit between the first electrode tab 21 and the second electrode tab 26 on the one hand; on the other hand, it improves the stability of the structure of the battery cell 10 after stacking. Thus, the technical effect of improving the reliability of the battery cell 10 is achieved.

[0167] Meanwhile, when the battery cell 10 with a general winding structure is placed in a plane parallel to the second direction Y, both sides of each layer of electrode sheet in the battery cell 10 with the winding structure are complete arc surfaces along the second direction Y. Therefore, these two sides do not have end faces that can be effectively infiltrated and exhausted. Only the two sides of each layer of electrode sheet in the battery cell 10 with the winding structure along the third direction Z respectively have end faces that can be effectively infiltrated and exhausted. That is, each layer of electrode sheet in the battery cell 10 with the winding structure only has two end faces that can be effectively infiltrated and exhausted. In this embodiment, when the electrode assembly 2 is placed in a plane parallel to the second direction Y, one side of each layer of the first flat portion 211 or the second flat portion 261 in the electrode assembly 2 along the second direction Y is an end face that can be effectively infiltrated and exhausted. At the same time, both sides of each layer of the first flat portion 211 or the second flat portion 261 in the electrode assembly 2 along the third direction Z respectively have an end face that can be effectively infiltrated and exhausted. That is, each layer of the first flat portion 211 or the second flat portion 261 in the electrode assembly 2 in this embodiment has three end faces that can be effectively infiltrated and exhausted. Thus, the number of end faces that can be effectively infiltrated and exhausted is increased, so the manufacturing efficiency of the battery cell 10 is also improved.

[0168] In some embodiments, please refer to Figure 5 and Figure 6 , Figure 5 which is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application (showing the first insulating layer). Figure 6 which is a schematic structural diagram of an electrode assembly provided in other embodiments of the present application (showing the first insulating layer). The first bending portion 212 is connected to one end of the first flat portion 211 along the second direction Y. Along the second direction Y, a first insulating layer 22 is provided at the end of the first flat portion 211 away from the first bending portion 212. The second direction Y is perpendicular to the first direction X.

[0169] The material of the first insulating layer 22 can be an insulating material. For example, the insulating material can be plastic, rubber, insulating glue, etc.

[0170] Along the second direction Y, the end face of the first flat portion 211 away from the first bending portion 212 is the first end face 2111. The first insulating layer 22 can cover a part of the first end face 2111 or can cover the entire first end face 2111.

[0171] Along the third direction Z, the length of the first insulating layer 22 can be greater than the length of the first flat portion 211, the length of the first insulating layer 22 can be equal to the length of the first flat portion 211, or the length of the first insulating layer 22 can be less than the length of the first flat portion 211.

[0172] In this embodiment, by providing a first insulating layer 22 at one end of the first straight portion 211 away from the first bending portion 212, the first insulating layer 22 can effectively cover the end face of the first straight portion 211, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0173] In some embodiments, please refer to Figure 7 , Figure 7 as Figure 6 the partial enlarged view of the A position in. The first insulating layer 22 includes a first insulating portion 221, a second insulating portion 222, and a third insulating portion 223 that are sequentially connected. Along the second direction Y, the second insulating portion 222 covers at least a part of the end face of the end of the first straight portion 211 away from the first bending portion 212. Along the first direction X, at least a part of the first insulating portion 221 is disposed on one side of the first straight portion 211, and at least a part of the third insulating portion 223 is disposed on the other side of the first straight portion 211.

[0174] The first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 can be integrally formed. When observing along the third direction Z, the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 can be sequentially connected to form a U-shaped structure. It can be that the thicknesses of the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 are equal, or it can be that the thicknesses of at least two of the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 are unequal.

[0175] The end face of the end of the first straight portion 211 away from the first bending portion 212 is the first end face 2111. The second insulating portion 222 is the part of the first insulating layer 22 disposed on the first end face 2111. The second insulating portion 222 can cover a part of the first end face 2111 or can cover the entire first end face 2111. It can be that the second insulating portion 222 is in contact with the first end face 2111, or it can be that the second insulating portion 222 is connected to the first end face 2111, for example, by bonding.

[0176] At least a part of the first insulating portion 221 is disposed on one side of the first straight portion 211. It can be that in the projection plane perpendicular to the first direction X, the orthographic projection of the first insulating portion 221 overlaps with the orthographic projection of one side of the first straight portion 211 partially or the orthographic projection of the first insulating portion 221 completely overlaps with the orthographic projection of one side of the first straight portion 211. It can be that the first insulating portion 221 is in contact with one side of the first straight portion 211, or it can be that the first insulating portion 221 is connected to one side of the first straight portion 211, for example, by bonding.

[0177] At least a part of the third insulating portion 223 is disposed on the other side of the first straight portion 211. In the projection plane perpendicular to the first direction X, the positive projection of the third insulating portion 223 may partially overlap with the positive projection of the other side of the first straight portion 211, or the positive projection of the third insulating portion 223 may completely overlap with the positive projection of the other side of the first straight portion 211. It may be that the third insulating portion 223 contacts the other side of the first straight portion 211, or the third insulating portion 223 is connected to the other side of the first straight portion 211, for example, by adhesion.

[0178] As an example, such as Figure 7 As shown, the first insulating layer 22 is an insulating tape, and the thicknesses of the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 are equal.

[0179] In this embodiment, by providing that the first insulating layer 22 is composed of the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223, and respectively defining the connection relationships between the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 and the end of the first straight portion 211, the connection between the first insulating layer 22 and the end of the first straight portion 211 is made firm, reducing the possibility of the first insulating layer 22 falling off.

[0180] In some embodiments, please continue to refer to Figure 7 . The thickness of the first insulating layer 22 is T1, the thickness of the first straight portion 211 is T2, and the thickness of the second straight portion 261 is T3, satisfying T1 ≤ T2 and T1 ≤ T3.

[0181] The relationship between T2 and T3 may be that T2 is equal to T3, T2 is greater than T3, or T2 is less than T3.

[0182] In the embodiment where the first insulating layer 22 includes the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 connected in sequence, the thicknesses of the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 may all be equal to the thickness of the first straight portion 211 and / or the thickness of the second straight portion 261, or the thicknesses of the first insulating portion 221, the second insulating portion 222, and the third insulating portion 223 may all be less than the thickness of the first straight portion 211 and / or the thickness of the second straight portion 261.

[0183] In this embodiment, by setting T1≤T2 and T1≤T3, the thickness of the first insulating layer 22 is within a suitable dimension range. On the one hand, the thickness of the first insulating layer 22 can be reduced, thereby reducing the risk of lithium deposition due to an excessive gap between the first electrode sheet 21 and the second electrode sheet 26 after stacking the battery cells 10. On the other hand, the thickness of the first insulating layer 22 can be increased, thereby reducing the risk of short circuit between the first electrode sheet 21 and the second electrode sheet 26 caused by burrs easily piercing the first insulating layer 22.

[0184] In some embodiments, please continue to refer to Figure 7 . In a cross-section perpendicular to the third direction Z, the dimension of the first insulating layer 22 in its extending direction is W1, and along the first direction X, the thickness of the first flat portion 211 is T2, satisfying 0mm≤W1 - 2×T2≤10mm, where the first direction X, the second direction Y, and the third direction Z are perpendicular to each other pairwise.

[0185] W1 - 2×T2 can be a point value of any one of 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.5mm, 2.8mm, 3mm, 3.3mm, 3.5mm, 3.8mm, 4mm, 4.3mm, 4.5mm, 4.8mm, 5mm, 5.3mm, 5.5mm, 5.8mm, 6mm, 6.3mm, 6.5mm, 6.8mm, 7mm, 7.3mm, 7.5mm, 7.8mm, 8mm, 8.3mm, 8.5mm, 8.8mm, 9mm, 9.3mm, 9.5mm, 9.8mm, 9.9mm, 10mm or a range value between any two of them.

[0186] In an embodiment where the first insulating layer 22 includes a first insulating portion 221, a second insulating portion 222, and a third insulating portion 223 connected in sequence, in a cross-section perpendicular to the third direction Z, the extending dimension of the first insulating portion 221 is W 1a , the extending dimension of the second insulating portion 222 is W 1b , the extending dimension of the third insulating portion 223 is W 1c , and W1 = W 1a + W 1b + W 1c .

[0187] In this embodiment, by setting 0mm≤W1 - 2×T2≤10mm, it is beneficial for the second insulating portion 222 to cover the end face of the first flat portion 211 away from the first bending portion 212, the first insulating portion 221 to partially cover one side of the end of the first flat portion 211 away from the first bending portion 212, and the third insulating portion 223 to partially cover the other side of the end of the first flat portion 211 away from the first bending portion 212, thereby reducing the possibility of the first insulating layer 22 falling off.

[0188] In some embodiments, please refer to Figure 8 , Figure 8 which is Figure 5 the B-direction view of the electrode assembly shown. Along the third direction Z, the length of the first insulating layer 22 is L1, and the length of the first flat portion 211 is L2, satisfying L1≥L2. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs.

[0189] As an example, L1>L2. Along the third direction Z, the first insulating layer 22 can extend beyond both ends of the first flat portion 211.

[0190] In this embodiment, by setting L1≥L2, the length of the first insulating layer 22 along the third direction Z is greater than or equal to the length of the first flat portion 211 along the third direction Z. Thus, along the third direction Z, it is beneficial for the first insulating layer 22 to cover a larger area of the end of the first flat portion 211 away from the first bending portion 212, thereby further reducing the contact between the burrs on the end face of the first flat portion 211 and the second flat portion 261, and further reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0191] In some embodiments, please continue to refer to Figure 8 . Along the third direction Z, the length of the second flat portion 261 is L5, satisfying L5>L2 and L1≥L5.

[0192] As an example, the second pole piece 26 is a negative pole piece, and the first pole piece 21 is a positive pole piece. Along the third direction Z, the portion of the second active material layer 264 ( Figure 8 not shown in the figure) located on the second flat portion 261 extends beyond both ends of the portion of the first active material layer 214 ( Figure 8 not shown in the figure) located on the first flat portion 211.

[0193] In this embodiment, first, the length of the second flat portion 261 along the third direction Z is set to be greater than the length of the first flat portion 211 along the third direction Z, thereby reducing the risk of lithium deposition. However, after such a setting, when the battery cells 10 are stacked, between the adjacent first flat portion 211 and the second flat portion 261, in the third direction Z, the second flat portion 261 will have a local area extending beyond the first flat portion 211, resulting in local stress concentration in this part. Therefore, by making the length of the first insulating layer 22 along the third direction Z greater than the length of the second flat portion 261 along the third direction Z, in the third direction Z, a part of the first insulating layer 22 can extend beyond the second flat portion 261. This extended part can support the local area where the second flat portion 261 extends beyond after the battery cells 10 are stacked, thereby reducing the local stress concentration in this part.

[0194] In some embodiments, please refer toFigures 9 - 11 , Figure 9 A schematic structural diagram of an electrode assembly provided by some embodiments of the present application (showing a first insulating layer and a second insulating layer). Figure 10 is Figure 9 a partial enlarged schematic view of point C in Figure 11 is Figure 9 a D-direction view of the shown electrode assembly. The second bending portion 262 is connected to one end of the second straight portion 261 along the second direction Y. Along the second direction Y, a second insulating layer 27 is provided at one end of the second straight portion 261 away from the second bending portion 262. The second direction Y is perpendicular to the first direction X.

[0195] The material of the second insulating layer 27 may be an insulating material. For example, the insulating material may be plastic, rubber, insulating glue, etc.

[0196] Along the second direction Y, the end face of one end of the second straight portion 261 away from the second bending portion 262 is the second end face 2611. The second insulating layer 27 may cover a part of the second end face 2611 or may cover the entire second end face 2611.

[0197] Along the third direction Z, the length of the second insulating layer 27 may be greater than the length of the second straight portion 261, the length of the second insulating layer 27 may be equal to the length of the second straight portion 261, or the length of the second insulating layer 27 may be less than the length of the second straight portion 261.

[0198] In this embodiment, by providing the second insulating layer 27 at one end of the second straight portion 261 away from the second bending portion 262, the end face of the second straight portion 261 can be effectively covered by the second insulating layer 27, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0199] Please continue to refer to Figure 10 , the second insulating layer 27 includes a fourth insulating portion 271, a fifth insulating portion 272, and a sixth insulating portion 273 that are connected in sequence. Along the second direction Y, the fifth insulating portion 272 covers at least a part of the end face of one end of the second straight portion 261 away from the second bending portion 262. Along the first direction X, at least a part of the fourth insulating portion 271 is provided on one side of the second straight portion 261, and at least a part of the fourth insulating portion 271 is provided on the other side of the second straight portion 261.

[0200] The fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 can be integrally formed. The fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 can be sequentially connected to form a U-shaped structure. The thicknesses of the fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 can be equal, or at least two of the fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 can have unequal thicknesses.

[0201] The end face of one end of the second straight portion 261 away from the second bent portion 262 is the second end face 2611. The fifth insulating portion 272 is the portion of the second insulating layer 27 disposed on the second end face 2611. The fifth insulating portion 272 can cover a part of the second end face 2611 or can cover the entire second end face 2611. The fifth insulating portion 272 can be in contact with the second end face 2611, or the fifth insulating portion 272 can be connected to the second end face 2611, for example, by adhesion.

[0202] At least a part of the fourth insulating portion 271 is disposed on one side of the second straight portion 261. In the projection plane perpendicular to the first direction X, the orthographic projection of the fourth insulating portion 271 and the orthographic projection of one side of the second straight portion 261 can partially overlap or the orthographic projection of the fourth insulating portion 271 and the orthographic projection of one side of the second straight portion 261 can completely overlap. The fourth insulating portion 271 can be in contact with one side of the second straight portion 261, or the fourth insulating portion 271 can be connected to one side of the second straight portion 261, for example, by adhesion.

[0203] At least a part of the sixth insulating portion 273 is disposed on the other side of the second straight portion 261. In the projection plane perpendicular to the first direction X, the orthographic projection of the sixth insulating portion 273 and the orthographic projection of the other side of the second straight portion 261 can partially overlap or the orthographic projection of the sixth insulating portion 273 and the orthographic projection of the other side of the second straight portion 261 can completely overlap. The sixth insulating portion 273 can be in contact with the other side of the second straight portion 261, or the sixth insulating portion 273 can be connected to the other side of the second straight portion 261, for example, by adhesion.

[0204] As an example, as Figure 10 shown, the second insulating layer 27 is an insulating tape, and the thicknesses of the fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 are equal.

[0205] In this embodiment, by providing that the second insulating layer 27 is composed of the fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273, and respectively defining the connection relationships between the fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 and the end of the second straight portion 261, the connection between the second insulating layer 27 and the end of the second straight portion 261 is made firm, reducing the possibility of the second insulating layer 27 falling off.

[0206] Please continue to refer to Figure 11 where the thickness of the second insulating layer 27 is T5, the thickness of the first flat portion 211 is T2, and the thickness of the second flat portion 261 is T3, satisfying T5 ≤ T2 and T5 ≤ T3.

[0207] The relationship between T2 and T3 can be that T2 is equal to T3, T2 is greater than T3, or T2 is less than T3.

[0208] In an embodiment where the second insulating layer 27 includes a fourth insulating portion 271, a fifth insulating portion 272, and a sixth insulating portion 273 connected in sequence, the thicknesses of the fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 can all be equal to the thickness of the first flat portion 211 and / or the thickness of the second flat portion 261, or the thicknesses of the fourth insulating portion 271, the fifth insulating portion 272, and the sixth insulating portion 273 can all be less than the thickness of the first flat portion 211 and / or the thickness of the second flat portion 261.

[0209] In this embodiment, by setting T5 ≤ T2 and T5 ≤ T3, the thickness of the second insulating layer 27 is within a suitable dimension range. On the one hand, this can reduce the thickness of the second insulating layer 27 and lower the risk of lithium deposition due to an excessive gap between the first electrode plate 21 and the second electrode plate 26 after the battery cells 10 are stacked. On the other hand, it can increase the thickness of the second insulating layer 27 and reduce the risk of the burr easily piercing the second insulating layer 27 and causing a short circuit between the first electrode plate 21 and the second electrode plate 26.

[0210] Please continue to refer to Figure 10 . In a cross-section perpendicular to the third direction Z, the dimension of the second insulating layer 27 in its extending direction is W3, and along the first direction X, the thickness T3 of the second flat portion 261 satisfies 0 mm ≤ W3 - 2×T3 ≤ 10 mm, where the first direction X, the second direction Y, and the third direction Z are perpendicular to each other pairwise.

[0211] W3 - 2×T3 can be a point value of any one of 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.3 mm, 3.5 mm, 3.8 mm, 4 mm, 4.3 mm, 4.5 mm, 4.8 mm, 5 mm, 5.3 mm, 5.5 mm, 5.8 mm, 6 mm, 6.3 mm, 6.5 mm, 6.8 mm, 7 mm, 7.3 mm, 7.5 mm, 7.8 mm, 8 mm, 8.3 mm, 8.5 mm, 8.8 mm, 9 mm, 9.3 mm, 9.5 mm, 9.8 mm, 9.9 mm, 10 mm or a range value between any two of them.

[0212] In an embodiment where the second insulating layer 27 includes a fourth insulating portion 271, a fifth insulating portion 272, and a sixth insulating portion 273 that are sequentially connected, the extension dimension of the fourth insulating portion 271 in a cross-section perpendicular to the third direction Z is W 3a , the extension dimension of the fifth insulating portion 272 is W 3b , the extension dimension of the sixth insulating portion 273 is W 3c , W3 = W 3a +W 3b +W 3c .

[0213] In this embodiment, by setting 0 mm ≤ W3 - 2×T3 ≤ 10 mm, it is beneficial for the fifth insulating portion 272 to cover the end face of the second straight portion 261 away from the second bending portion 262, the fourth insulating portion 271 to partially cover one side of the end of the second straight portion 261 away from the second bending portion 262, and the sixth insulating portion 273 to partially cover the other side of the end of the second straight portion 261 away from the second bending portion 262, thereby reducing the possibility of the second insulating layer 27 falling off.

[0214] Please continue to refer to Figure 11 . Along the third direction Z, the length of the second insulating layer 27 is L3, and the length L5 of the second straight portion 261 satisfies L3 ≥ L5, and the first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs.

[0215] As an example, L3 > L5. Along the third direction Z, the second insulating layer 27 can extend beyond both ends of the second straight portion 261.

[0216] In this embodiment, by setting L3 ≥ L5, the length of the second insulating layer 27 along the third direction Z is greater than or equal to the length of the second straight portion 261 along the third direction Z. Thus, along the third direction Z, it is beneficial for the second insulating layer 27 to cover a larger area of one end of the second straight portion 261 away from the second bending portion 262, thereby further reducing the contact between the burrs on the end face of the second straight portion 261 and the first straight portion 211, and further reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0217] Please continue to refer to Figure 11 . Along the third direction Z, the length of the first straight portion 211 is L2, which satisfies L5 > L2 and L3 ≥ L5.

[0218] As an example, the second pole piece 26 is a negative pole piece, and the first pole piece 21 is a positive pole piece. Along the third direction Z, the portion of the second active material layer 264 ( Figure 11 not shown in the figure) located on the second straight portion 261 extends beyond both ends of the portion of the first active material layer 214 ( Figure 11 not shown in the figure) located on the first straight portion 211.

[0219] In this embodiment, first, the length of the second straight portion 261 along the third direction Z is set to be greater than the length of the first straight portion 211 along the third direction Z, thereby reducing the risk of lithium plating. However, after such a setting, when the battery cells 10 are stacked, between the adjacent first straight portion 211 and the second straight portion 261, in the third direction Z, a partial area of the second straight portion 261 will exceed the first straight portion 211, resulting in local stress concentration in this part. Therefore, by setting the length of the second insulating layer 27 along the third direction Z to be greater than the length of the second straight portion 261 along the third direction Z, a partial area of the second insulating layer 27 can exceed the second straight portion 261 in the third direction Z. This exceeded part can support the local area where the second straight portion 261 exceeds after the battery cells 10 are stacked, thereby reducing the local stress concentration in this part.

[0220] In some embodiments, please continue to refer to Figure 12 , Figure 12 is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application (showing the third insulating layer). A third insulating layer 23 is provided on the side of the first bending portion 212 facing the second straight portion 261.

[0221] The material of the third insulating layer 23 can be an insulating material. For example, the insulating material can be plastic, rubber, insulating glue, etc.

[0222] The first bending portion 212 has opposite first and second surfaces. Among them, the first surface faces the second straight portion 261, and the third insulating layer 23 is provided on the first surface.

[0223] The third insulating layer 23 may be in contact with the first surface, or the third insulating layer 23 may be connected to the first surface, such as by bonding.

[0224] In an embodiment where the first bending portion 212 includes a first current collector portion 2131, the first surface may be the surface of the first current collector portion 2131 facing the second straight portion 261.

[0225] In an embodiment where the first bending portion 212 includes a first current collector portion 2131 and a first active material portion 2141, and the first active material portion 2141 can be provided on both opposite surfaces of the first current collector portion 2131, the second surface may be the surface of the first active material portion 2141 facing the second straight portion 261 and not in contact or connection with the first current collector portion 2131.

[0226] In this embodiment, by providing a third insulating layer 23 on the side of the first bending portion 212 facing the second straight portion 261, the side of the first bending portion 212 facing the second straight portion 261 has insulating properties. In this way, even when the burr at the end of the second straight portion 261 far from the second bending portion 262 contacts the first bending portion 212, since the surface of the first bending portion 212 has insulating properties, this burr will not cause a short circuit between the first bending portion 212 and the second straight portion 261, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0227] In some embodiments, please refer to Figure 13 , Figure 13 which is a schematic structural diagram of the electrode assembly provided in some other embodiments of the present application (showing the third insulating layer). The first bending portion 212 includes a first current collector portion 2131, and a third insulating layer 23 is provided on the side of the first current collector portion 2131 facing the second straight portion 261.

[0228] In some embodiments, please refer to Figure 14 , Figure 14 which is a schematic structural diagram of the electrode assembly provided in some embodiments of the present application (showing the third insulating layer and the fourth insulating layer). The first bending portion 212 includes a first current collector portion 2131 and a first active material portion 2141. A first active material portion 2141 is provided on the side of the first current collector portion 2131 facing the second straight portion 261, and a third insulating layer 23 is provided on the side of the first active material portion 2141 facing the second straight portion 261.

[0229] A third insulating layer 23 is provided on the side of the first current collector portion 2131 facing the second straight portion 261. It can be that the first current collector portion 2131 has opposite third and fourth surfaces, and at least one of the third and fourth surfaces is provided with the third insulating layer 23.

[0230] The third insulating layer 23 may be in contact with the third surface or the fourth surface, or the third insulating layer 23 may be connected to the third surface or the fourth surface, for example, by bonding.

[0231] A first active material portion 2141 is provided on the side of the first current collector portion 2131 facing the second straight portion 261. It can be that the first current collector portion 2131 has opposite third and fourth surfaces, and at least one of the third and fourth surfaces is provided with the first active material portion 2141.

[0232] On one side of the first active material portion 2141 facing the second flat portion 261, a third insulating layer 23 is provided. It can be that the first active material portion 2141 has opposite fifth and sixth surfaces, where the fifth surface is close to the first current collector portion 2131 and the sixth surface is away from the first current collector portion 2131, and the third insulating layer 23 is provided on the sixth surface.

[0233] It can be that the third insulating layer 23 is in contact with the sixth surface, or the third insulating layer 23 is connected to the sixth surface, for example, by adhesion.

[0234] In this embodiment, by providing the third insulating layer 23 on one side of the first current collector portion 2131 facing the second flat portion 261 or on one side of the first active material portion 2141 facing the second flat portion 261, one side of the first current collector portion 2131 facing the second flat portion 261 or one side of the first active material portion 2141 facing the second flat portion 261 has insulating properties. In this way, even when the burr at the end of the second flat portion 261 away from the second bent portion 262 contacts the first current collector portion 2131 or the first active material portion 2141, due to the insulating properties of the surface of the first current collector portion 2131 or the first active material portion 2141, the burr will not cause a short circuit between the first current collector portion 2131 and the second flat portion 261 or between the first active material portion 2141 and the second flat portion 261, thereby reducing the risk of short circuit between the first electrode sheet 21 and the second electrode sheet 26.

[0235] In some embodiments, please continue to refer to Figure 14 . A fourth insulating layer 24 is provided on the side of the first bent portion 212 facing away from the second flat portion 261.

[0236] The material of the fourth insulating layer 24 can be an insulating material. For example, the insulating material can be plastic, rubber, insulating glue, etc.

[0237] The first bent portion 212 has opposite first and second surfaces, where the second surface faces away from the second flat portion 261, and the fourth insulating layer 24 is provided on the second surface.

[0238] It can be that the fourth insulating layer 24 is in contact with the second surface, or the fourth insulating layer 24 is connected to the second surface, for example, by adhesion.

[0239] In an embodiment where the first bent portion 212 includes the first current collector portion 2131, it can be that the second surface is the surface of the first current collector portion 2131 on the side facing away from the second flat portion 261.

[0240] In an embodiment where the first bending portion 212 includes a first current collector portion 2131 and a first active material portion 2141, and the first active material portion 2141 can be provided on both opposite surfaces of the first current collector portion 2131, the second surface can be the surface of the first active material portion 2141 facing away from the second straight portion 261 and not in contact or connection with the first current collector portion 2131.

[0241] In this embodiment, by providing the fourth insulating layer 24 on the side of the first bending portion 212 facing away from the second straight portion 261, the side of the first bending portion 212 facing away from the second straight portion 261 has insulating properties. In this way, even when a burr at the end of the second straight portion 261 far from the second bending portion 262 contacts the first bending portion 212, since the surface of the first bending portion 212 has insulating properties, the burr will not cause a short circuit between the first bending portion 212 and the second straight portion 261, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0242] In some embodiments, please refer to Figure 15 , Figure 15 is Figure 14 a partial enlarged schematic view of the E position in. The first bending portion 212 is connected to one end of the first straight portion 211 along the second direction Y. In a cross-section perpendicular to the third direction Z, the dimension of the fourth insulating layer 24 in its extending direction is W2, the thickness of the first straight portion 211 along the first direction X is T2, and the dimension of the second straight portion 261 is T3, satisfying 0 mm ≤ W2 - (2 × T2 + T3) ≤ 10 mm, and the first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs.

[0243] W2 - (2 × T2 + T3) can be a point value of any one of 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.3 mm, 3.5 mm, 3.8 mm, 4 mm, 4.3 mm, 4.5 mm, 4.8 mm, 5 mm, 5.3 mm, 5.5 mm, 5.8 mm, 6 mm, 6.3 mm, 6.5 mm, 6.8 mm, 7 mm, 7.3 mm, 7.5 mm, 7.8 mm, 8 mm, 8.3 mm, 8.5 mm, 8.8 mm, 9 mm, 9.3 mm, 9.5 mm, 9.8 mm, 9.9 mm, 10 mm or a range value between any two of them.

[0244] In this embodiment, by setting 0 mm ≤ W2 - (2 × T2 + T3) ≤ 10 mm, after the battery cells 10 are stacked, it is beneficial for the fourth insulating layer 24 to better cover the side of the first bending portion 212 facing away from the second straight portion 261, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0245] In some embodiments, please continue to refer to Figure 15 . The thicknesses of the third insulating layer 23 and the fourth insulating layer 24 are both T4, the thickness of the first straight portion 211 is T2, and the thickness of the second straight portion 261 is T3, satisfying T4 ≤ T2 and T4 ≤ T3.

[0246] The relationship between T2 and T3 can be that T2 is equal to T3, T2 is greater than T3, or T2 is less than T3.

[0247] In this embodiment, by setting T4 ≤ T2 and T4 ≤ T3, the thicknesses of the third insulating layer 23 and the fourth insulating layer 24 are within a suitable dimension range. Thus, on the one hand, the thicknesses of the third insulating layer 23 and the fourth insulating layer 24 can be reduced, reducing the risk of lithium plating due to an excessive gap between the first electrode sheet 21 and the second electrode sheet 26 after stacking the battery cells 10; on the other hand, the thicknesses of the third insulating layer 23 and the fourth insulating layer 24 can be increased, reducing the risk of short circuit between the first electrode sheet 21 and the second electrode sheet 26 caused by burrs easily piercing the third insulating layer 23 or the fourth insulating layer 24.

[0248] In some embodiments, please refer to Figure 16 , Figure 16 is Figure 14 the F - direction view of the electrode assembly shown. The first bent portion 212 is connected to one end of the first straight portion 211 along the second direction Y. Along the third direction Z, the lengths of the third insulating layer 23 ( Figure 15 shown in) and the fourth insulating layer 24 are both L4, and the length of the first straight portion 211 is L2, satisfying L4 ≥ L2. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other pairwise.

[0249] As an example, L4 > L2, and the third insulating layer 23 or the fourth insulating layer 24 can extend beyond both ends of the first straight portion 211 along the third direction Z.

[0250] In this embodiment, by setting L4 ≥ L2, the length of the third insulating layer 23 or the fourth insulating layer 24 along the third direction Z is greater than or equal to the length of the first straight portion 211 along the third direction Z. Thus, along the third direction Z, it is beneficial for the third insulating layer 23 or the fourth insulating layer 24 to cover a larger area of the end of the first straight portion 211 away from the first bent portion 212, thereby further reducing the contact between the burrs on the end face of the first straight portion 211 and the second straight portion 261, and further reducing the risk of short circuit between the first electrode sheet 21 and the second electrode sheet 26.

[0251] In some embodiments, please continue to refer to Figure 16 . Along the third direction Z, the length of the second straight portion 261 is L5, satisfying L5 > L2 and L4 ≥ L5.

[0252] As an example, the second electrode tab 26 is a negative electrode tab, and the first electrode tab 21 is a positive electrode tab. Along the third direction Z, the portion of the second active material layer 264 ( Figure 16 not shown in) located in the second flat portion 261 extends beyond both ends of the portion of the first active material layer 214 ( Figure 16 not shown in) located in the first flat portion 211.

[0253] In this embodiment, first, the length of the second flat portion 261 along the third direction Z is set to be greater than the length of the first flat portion 211 along the third direction Z, thereby reducing the risk of lithium plating. However, after such a setting, when the battery cells 10 are stacked, between the adjacent first flat portion 211 and the second flat portion 261, in the third direction Z, the second flat portion 261 will have a local area extending beyond the first flat portion 211, resulting in local stress concentration in this part; therefore, by making the length of the third insulating layer 23 or the fourth insulating layer 24 along the third direction Z greater than the length of the second flat portion 261 along the third direction Z, so that in the third direction Z, a part of the third insulating layer 23 or the fourth insulating layer 24 can extend beyond the second flat portion 261, and the extended part can support the local area where the second flat portion 261 extends beyond after the battery cells 10 are stacked, thereby reducing the local stress concentration in this part.

[0254] In some embodiments, please refer to Figure 17 . Figure 17 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application (showing the third insulating layer 23, the fourth insulating layer 24, the fifth insulating layer 28, and the sixth insulating layer 29). A fifth insulating layer 28 is provided on the side of the second bent portion 262 facing the first flat portion 211.

[0255] The material of the fifth insulating layer 28 can be an insulating material. For example, the insulating material can be plastic, rubber, insulating glue, etc.

[0256] The second bent portion 262 has opposite seventh and eighth surfaces. Among them, the seventh surface is close to the first flat portion 211, and a third insulating layer 23 is provided on the seventh surface.

[0257] It can be that the third insulating layer 23 is in contact with the seventh surface, or the third insulating layer 23 is connected to the seventh surface, such as by bonding.

[0258] In this embodiment, by providing a fifth insulating layer 28 on the side of the second bending portion 262 facing the first straight portion 211, the side of the second bending portion 262 facing the first straight portion 211 has insulating properties. In this way, even when a burr at the end of the first straight portion 211 away from the first bending portion 212 comes into contact with the second bending portion 262, since the surface of the second bending portion 262 has insulating properties, this burr will not cause a short circuit between the second bending portion 262 and the first straight portion 211, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0259] In some embodiments, please continue to refer to Figure 17 . A sixth insulating layer 29 is provided on the side of the second bending portion 262 facing away from the first straight portion 211.

[0260] The material of the sixth insulating layer 29 can be an insulating material. For example, the insulating material can be plastic, rubber, insulating glue, etc.

[0261] The second bending portion 262 has opposite seventh and eighth surfaces, where the eighth surface faces away from the first straight portion 211, and the sixth insulating layer 29 is provided on the eighth surface.

[0262] It can be that the sixth insulating layer 29 is in contact with the eighth surface, or the sixth insulating layer 29 is connected to the eighth surface, for example, by bonding.

[0263] In this embodiment, by providing a sixth insulating layer 29 on the side of the second bending portion 262 facing away from the first straight portion 211, the side of the second bending portion 262 facing away from the first straight portion 211 has insulating properties. In this way, even when a burr at the end of the first straight portion 211 away from the first bending portion 212 comes into contact with the second bending portion 262, since the surface of the second bending portion 262 has insulating properties, this burr will not cause a short circuit between the second bending portion 262 and the first straight portion 211, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0264] In some embodiments, please refer to Figure 18 and Figure 19 , Figure 18 is a schematic structural diagram of the first pole piece provided in some embodiments of the present application. Figure 19Schematic diagram of the structure of the second pole piece provided by some embodiments of the present application. The first bending portion 212 is connected to one end of the first straight portion 211 along the second direction Y. The first pole piece 21 includes a first tab 25. A first tab 25 is provided at one end of each first straight portion 211 along the third direction Z. In the projection plane perpendicular to the first direction X, the orthographic projections of the first tabs 25 on the two first straight portions 211 in the first pole piece 21 at least partially overlap; and / or the second bending portion 262 is connected to one end of the second straight portion 261 along the second direction Y. The second pole piece 26 includes a second tab 30. A second tab 30 is provided at one end of each second straight portion 261 along the third direction Z. In the projection plane perpendicular to the first direction X, the orthographic projections of the second tabs 30 on the two second straight portions 261 in the second pole piece 26 at least partially overlap; the first direction X, the second direction, and the third direction Z are perpendicular to each other in pairs.

[0265] Along the third direction Z, the first straight portion 211 has opposite first and second ends. Among them, at least one of the first end and the second end is provided with a first tab 25. The first tab 25 can be directly connected to one end of the first straight portion 211. For example, the first tab 25 and the first straight portion 211 are directly connected by welding. The first tab 25 can be indirectly connected to one end of the first straight portion 211. For example, the first tab 25 and the first straight portion 211 are indirectly connected by riveting.

[0266] In the projection plane perpendicular to the first direction X, the orthographic projections of the first tabs 25 on the two first straight portions 211 in the first pole piece 21 at least partially overlap. It can be that the orthographic projections of the first tabs 25 on the two first straight portions 211 partially overlap, or it can be that the orthographic projections of the first tabs 25 on the two first straight portions 211 completely overlap.

[0267] Along the third direction Z, the second straight portion 261 has opposite third and fourth ends. Among them, at least one of the third end and the fourth end is provided with a second tab 30. The second tab 30 can be directly connected to one end of the second straight portion 261. For example, the second tab 30 and the second straight portion 261 are directly connected by welding. The second tab 30 can be indirectly connected to one end of the second straight portion 261. For example, the second tab 30 and the second straight portion 261 are indirectly connected by riveting.

[0268] In the projection plane perpendicular to the first direction X, the orthographic projections of the second tabs 30 on the two second straight portions 261 in the second pole piece 26 at least partially overlap. It can be that the orthographic projections of the second tabs 30 on the two second straight portions 261 partially overlap, or it can be that the orthographic projections of the second tabs 30 on the two second straight portions 261 completely overlap.

[0269] In the embodiments of the present application, by setting the orthographic projections of the first tabs 25 on the two first flat portions 211 to at least partially overlap, it is convenient for the first tabs 25 to be connected to each other. By setting the orthographic projections of the second tabs 30 on the two second flat portions 261 to at least partially overlap, it is convenient for the second tabs 30 to be connected to each other.

[0270] In some embodiments, please refer to Figure 20 and Figure 21 , Figure 20 which is a schematic structural diagram of the electrode assembly provided in some embodiments of the present application (showing the first strengthening portion and the second strengthening portion), Figure 21 which is a schematic structural diagram of the electrode assembly 2 provided in other embodiments of the present application (showing the first strengthening portion 31 and the second strengthening portion 32). The first bending portion 212 includes a first current collecting portion 2131, and the first current collecting portion 2131 is provided with a first strengthening portion 31; and / or, the second bending portion 262 includes a second current collecting portion 2631, and the second current collecting portion 2631 is provided with a second strengthening portion 32.

[0271] The first current collecting portion 2131 may be a part of the first current collector 213 disposed on the first bending portion 212.

[0272] The second current collecting portion 2631 may be a part of the second current collector 263 disposed on the second bending portion 262.

[0273] It may be that both opposite surfaces of the first current collecting portion 2131 are provided with the first strengthening portion 31.

[0274] It may be that both opposite surfaces of the second current collecting portion 2631 are provided with the second strengthening portion 32.

[0275] The first strengthening portion 31 may be one or more. If there are multiple ones, multiple first strengthening portions 31 may be arranged at intervals along the extending direction of the first current collecting portion 2131, or multiple first strengthening portions 31 may be arranged at intervals along the third direction Z.

[0276] The first strengthening portion 31 may be a welding mark protruding from the surface of the first current collecting portion 2131, or a protrusion integrally formed with the first current collecting portion 2131.

[0277] The second strengthening portion 32 may be one or more. If there are multiple ones, multiple second strengthening portions 32 may be arranged at intervals along the extending direction of the second current collecting portion 2631, or multiple second strengthening portions 32 may be arranged at intervals along the third direction Z.

[0278] The second strengthening portion 32 may be a welding mark protruding from the surface of the second current collecting portion 2631, or a protrusion integrally formed with the second current collecting portion 2631.

[0279] The first reinforcing part 31 can be a strip-shaped structure extending along the third direction Z. Along the third direction Z, the length of the first reinforcing part 31 can be greater than the length of the first current collecting part 2131, can be equal to the length of the first current collecting part 2131, or can be less than the length of the first current collecting part 2131.

[0280] The second reinforcing part 32 can be a strip-shaped structure extending along the third direction Z. Along the third direction Z, the length of the second reinforcing part 32 can be greater than the length of the second current collecting part 2631, can be equal to the length of the second current collecting part 2631, or can be less than the length of the second current collecting part 2631.

[0281] In this embodiment, by providing the first reinforcing part 31, the strength of the first bent part 212 is improved, so that when the battery cells 10 are stacked, the occurrence of defects such as wrinkling of the first bent part 212 is reduced.

[0282] In this embodiment, by providing the second reinforcing part 32, the strength of the second bent part 262 is improved, so that when the battery cells 10 are stacked, the occurrence of defects such as wrinkling of the second bent part 262 is reduced.

[0283] In some embodiments, please continue to refer to Figure 21 . The first bent part 212 is connected to one end of the first straight part 211 along the second direction Y, and the second bent part 262 is connected to one end of the second straight part 261 along the second direction Y away from the first bent part 212, and the second direction Y is perpendicular to the first direction X.

[0284] In the projection plane perpendicular to the third direction Z, the orthographic projection of the first bent part 212 and the orthographic projection of the second bent part 262 may not overlap, or the orthographic projection of the first bent part 212 and the orthographic projection of the second bent part 262 may be arranged at intervals.

[0285] In this embodiment, by arranging the first bent part 212 and the second bent part 262 at intervals, after the battery cells 10 are stacked, the arrangement of the first electrode sheet 21 and the second electrode sheet 26 is more reasonable.

[0286] In some embodiments, please refer to Figure 22 , Figure 22 is an electrode assembly 2 provided in some embodiments of the present application (showing the first electrode sheet 21, the second electrode sheet 26 and the third electrode sheet 33). Both the first electrode sheet 21 and the second electrode sheet 26 are multiple, and along the first direction X, the first straight part 211 and the second straight part 261 are alternately arranged.

[0287] Both the first electrode sheet 21 and the second electrode sheet 26 are multiple, the first electrode sheet 21 is a positive electrode sheet, and the second electrode sheet 26 is a negative electrode sheet.

[0288] Both the first flat portion 211 and the second flat portion 261 are multiple. Among the multiple first flat portions 211, a second flat portion 261 is clamped between adjacent first flat portions 211. Among the multiple second flat portions 261, a first flat portion 211 is clamped between adjacent second flat portions 261.

[0289] In an embodiment where the first electrode sheet 21 is a positive electrode sheet and the second electrode sheet 26 is a negative electrode sheet, the electrode assembly 2 may include a third electrode sheet 33. The third electrode sheet 33 may have the same polarity as the second electrode sheet 26. The third electrode sheet 33 and the second electrode sheet 26 may both be negative electrode sheets. Along the first direction X, the third electrode sheet 33 and the second electrode sheet 26 far from the third electrode sheet 33 are respectively located on both sides of the electrode assembly 2.

[0290] In this embodiment, by alternately arranging the multiple first flat portions 211 and the multiple second flat portions 261, after the battery cells 10 are stacked, the arrangement of the first electrode sheet 21 and the second electrode sheet 26 is more reasonable.

[0291] In some embodiments, please continue to refer to Figure 21 . The first electrode sheet 21 includes a first current collector 213 and a first active material layer 214. The first active material layer 214 is disposed on the surface of the first current collector 213. The portion of the first current collector 213 located at the first bent portion 212 is the first current collecting portion 2131, and the portion of the first current collector 213 located at the first flat portion 211 is the third current collecting portion 2132. The first current collecting portion 2131 and the third current collecting portion 2132 are integrally formed; and / or, the second electrode sheet 26 includes a second current collector 263 and a second active material layer 264. The second active material layer 264 is disposed on the surface of the second current collector 263. The portion of the second current collector 263 located at the second bent portion 262 is the second current collecting portion 2631, and the portion of the second current collector 263 located at the second flat portion 261 is the fourth current collecting portion 2632. The second current collecting portion 2631 and the fourth current collecting portion 2632 are integrally formed.

[0292] It may be that the first active material layer 214 is disposed on both opposite surfaces of the first current collector 213.

[0293] It may be that the second active material layer 264 is disposed on both opposite surfaces of the second current collector 263.

[0294] In this embodiment, by setting the first current collector 213 to include a first current collecting portion 2131 and a third current collecting portion 2132, and integrally forming the first current collecting portion 2131 and the third current collecting portion 2132, it is convenient for the processing and forming of the first pole piece 21. By setting the second current collector 263 to include a second current collecting portion 2631 and a fourth current collecting portion 2632, and integrally forming the second current collecting portion 2631 and the fourth current collecting portion 2632, it is convenient for the processing and forming of the second pole piece 26.

[0295] An embodiment of the present application provides a battery device 100, including the battery cell 10 provided in any one of the above embodiments.

[0296] An embodiment of the present application provides an electrical device, including the battery cell 10 provided in any one of the above embodiments.

[0297] An embodiment of the present application provides an electrode assembly 2, including a first pole piece 21, including a first bending portion 212 and two first flat portions 211. The two first flat portions 211 are arranged at intervals along the first direction X, and the first bending portion 212 connects the two first flat portions 211; a second pole piece 26, the second pole piece 26 has a polarity opposite to that of the first pole piece 21. The second pole piece 26 includes a second bending portion 262 and two second flat portions 261. The two second flat portions 261 are arranged at intervals along the first direction X, and the second bending portion 262 connects the two second flat portions 261. One first flat portion 211 is arranged between the two second flat portions 261 of the second pole piece 26, and one second flat portion 261 is arranged between the two first flat portions 211 of the first pole piece 21.

[0298] In some embodiments, the first bending portion 212 is connected to one end of the first flat portion 211 along the second direction Y. Along the second direction Y, a first insulating layer 22 is provided at one end of the first flat portion 211 away from the first bending portion 212, and the second direction Y is perpendicular to the first direction X.

[0299] In some embodiments, a third insulating layer 23 is provided on a side of the first bending portion 212 facing the second flat portion 261.

[0300] Please continue to refer to Figure 22The present application provides a battery cell 10, including an electrode assembly 2, the electrode assembly 2 including a first electrode sheet 21, the first electrode sheet 21 including a first bent portion 212 and two first straight portions 211, the two first straight portions 211 are arranged at intervals along the first direction X, and the first bent portion 212 connects the two first straight portions 211; the first electrode sheet 21 includes a first current collector 213 and a first active material layer 214, the first active material layer 214 is arranged on the surface of the first current collector 213, the portion of the first current collector 213 located at the first bent portion 212 is a first current collector 2131, and the portion of the first current collector 213 located at the first straight portion 211 is a third current collector 2132, and the first current collector 2131 and the third current collector 2132 are formed integrally. The second electrode piece 26 has an opposite polarity to that of the first electrode piece 21. The second electrode piece 26 is a negative electrode piece, and the first electrode piece 21 is a positive electrode piece. The second electrode piece 26 includes a second bent portion 262 and two second straight portions 261. The two second straight portions 261 are arranged at intervals along the first direction X. The second bent portion 262 connects the two second straight portions 261. The second electrode piece 26 includes a second current collector 263 and a second active material layer 264. The second active material layer 264 is arranged on the surface of the second current collector 263. The portion of the second current collector 263 located at the second bent portion 262 is a second current collector 2631. The portion of the second current collector 263 located at the second straight portion 261 is a fourth current collector 2632. The second current collector 2631 and the fourth current collector 2632 are integrally formed. A first straight portion 211 is provided between the two second straight portions 261 in the second pole piece 26, and a second straight portion 261 is provided between the two first straight portions 211 in the first pole piece 21. There are multiple first pole pieces 21 and second pole pieces 26. Along the first direction X, the first straight portions 211 and the second straight portions 261 are alternately provided. The first bent portion 212 and the second bent portion 262 are spaced apart along the second direction Y. Along the second direction Y, the first straight portion 211 is away from the first bent portion 21 2 is provided with a first insulating layer 22, a third insulating layer 23 is provided on the side of the first bent portion 212 facing the second straight portion 261, and a fourth insulating layer 24 is provided on the side of the first bent portion 212 away from the second straight portion 261. The electrode assembly 2 also includes a third electrode piece 33, and the third electrode piece 33 can have the same polarity as the second electrode piece 26. The third electrode piece 33 is a negative electrode piece. Along the first direction X, the third electrode piece 33 and the second electrode piece 26 away from the third electrode piece 33 are respectively located on both sides of the electrode assembly 2.

[0301] In such a battery cell 10, by setting the first bending portions 212 to be respectively connected to the two first straight portions 211, the cutting end faces at the ends where the first straight portions 211 are connected to the first bending portions 212 are eliminated, thereby reducing the probability of burrs appearing on the first pole piece 21. At the same time, the second bending portions 262 are set to be respectively connected to the two second straight portions 261, and the end faces at the ends where the second straight portions 261 are connected to the second bending portions 262 are eliminated, thereby reducing the probability of burrs appearing on the second pole piece 26, and further reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26. The burrs on the end face of the first straight portion 211 can be effectively wrapped by the first insulating layer 22, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26. By providing the third insulating layer 23 and the fourth insulating layer 24, the surface of the first bending portion 212 has insulating properties, thereby reducing the risk of short circuit between the first pole piece 21 and the second pole piece 26.

[0302] In summary, the structure of the battery cell 10 effectively reduces the risk of short circuit between the first pole piece 21 and the second pole piece 26, and further improves the reliability of the battery cell 10.

[0303] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0304] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that, An electrode assembly is included, the electrode assembly comprising: A first pole piece, comprising a first bent portion and two first straight portions, wherein the two first straight portions are spaced apart along a first direction, and the first bent portion connects the two first straight portions; The second pole piece has a polarity opposite to that of the first pole piece, and the second pole piece includes a second bent portion and two second straight portions, the two second straight portions are arranged at intervals along the first direction, the second bent portion connects the two second straight portions, one first straight portion is arranged between the two second straight portions in the second pole piece, and one second straight portion is arranged between the two first straight portions in the first pole piece.

2. The battery cell according to claim 1, characterized in that, The first bending portion is connected to one end of the first straight portion along a second direction. Along the second direction, a first insulating layer is provided at one end of the first straight portion away from the first bending portion. The second direction is perpendicular to the first direction.

3. The battery cell according to claim 2, wherein The first insulating layer includes a first insulating portion, a second insulating portion and a third insulating portion connected in sequence. Along the second direction, the second insulating portion covers at least a portion of the end surface of the first straight portion away from the first bent portion. Along the first direction, at least a portion of the first insulating portion is arranged on one side of the first straight portion, and at least a portion of the third insulating portion is arranged on the other side of the first straight portion.

4. The battery cell according to claim 2, wherein The thickness of the first insulating layer is T1, the thickness of the first straight portion is T2, and the thickness of the second straight portion is T3, satisfying T1≤T2 and T1≤T3.

5. The battery cell according to claim 2, characterized in that, In a cross section perpendicular to the third direction, the dimension of the first insulating layer in its extension direction is W1, and along the first direction, the thickness of the first straight portion is T2, satisfying 0mm≤W1-2×T2≤10mm, and the first direction, the second direction and the third direction are perpendicular to each other.

6. The battery cell according to claim 2, characterized in that, Along the third direction, the length of the first insulating layer is L1, the length of the first straight portion is L2, L1≥L2 is satisfied, and the first direction, the second direction and the third direction are perpendicular to each other.

7. The battery cell according to claim 6, characterized in that, Along the third direction, the length of the second straight portion is L5, satisfying L5>L2, and L1≥L5.

8. The battery cell according to claim 2, wherein, The second bending portion is connected to one end of the second straight portion along the second direction. Along the second direction, a second insulating layer is provided at one end of the second straight portion away from the second bending portion. The second direction is perpendicular to the first direction.

9. The battery cell according to claim 1, characterized in that, A third insulating layer is provided on a side of the first bent portion facing the second straight portion.

10. The battery cell according to claim 9, characterized in that, The first bent portion includes a first current collecting portion, and the third insulating layer is provided on the surface of the first current collecting portion facing the second straight portion; or the first bent portion includes a first current collecting portion and a first active material portion, and the first active material portion is provided on the surface of the first current collecting portion facing the second straight portion, and the third insulating layer is provided on the surface of the first active material portion facing the second straight portion.

11. The battery cell according to claim 9, wherein, A fourth insulating layer is provided on a side of the first bent portion facing away from the second straight portion.

12. The battery cell according to claim 11, wherein The first bent portion is connected to one end of the first straight portion along the second direction. In a cross section perpendicular to the third direction, the dimension of the fourth insulating layer in its extension direction is W2. Along the first direction, the thickness of the first straight portion is T2, and the dimension of the second straight portion is T3, satisfying 0mm≤W2-(2×T2+T3)≤10mm, and the first direction, the second direction, and the third direction are perpendicular to each other.

13. The battery cell according to claim 11, wherein The thickness of the third insulating layer and the fourth insulating layer are both T4, the thickness of the first straight portion is T2, and the thickness of the second straight portion is T3, satisfying T4≤T2 and T4≤T3.

14. The battery cell according to claim 11, wherein The first bent portion is connected to one end of the first straight portion along the second direction. Along the third direction, the lengths of the third insulating layer and the fourth insulating layer are both L4, and the length of the first straight portion is L2, satisfying L4≥L2. The first direction, the second direction and the third direction are perpendicular to each other.

15. The battery cell according to claim 14, wherein Along the third direction, the length of the second straight portion is L5, satisfying L5>L2, and L4≥L5.

16. The battery cell according to claim 9, wherein A fifth insulating layer is provided on a side of the second bent portion facing the first straight portion.

17. The battery cell according to claim 16, characterized in that, A sixth insulating layer is provided on a side of the second bent portion facing away from the first straight portion.

18. The battery cell according to any one of claims 1-17, characterized in that, The first bent portion is connected to one end of the first straight portion along the second direction, the first pole piece includes a first pole lug, and each of the first straight portions is provided with a first pole lug at one end along the third direction, and in a projection plane perpendicular to the first direction, the orthographic projections of the first pole lugs on two of the first straight portions of the first pole piece at least partially overlap; and / or the second bent portion is connected to one end of the second straight portion along the second direction, the second pole piece includes a second pole lug, and each of the second straight portions is provided with a second pole lug at one end along the third direction, and in a projection plane perpendicular to the first direction, the orthographic projections of the second pole lugs on two of the second straight portions of the second pole piece at least partially overlap; The first direction, the second direction and the third direction are perpendicular to each other.

19. The battery cell according to any one of claims 1-17, characterized in that, The first bending portion includes a first current collecting portion, and the first current collecting portion is provided with a first reinforcement portion; and / or the second bending portion includes a second current collecting portion, and the second current collecting portion is provided with a second reinforcement portion.

20. The battery cell according to any one of claims 1 to 17, characterized in that: The first bending portion is connected to one end of the first straight portion along the second direction, and the second bending portion is connected to one end of the second straight portion along the second direction away from the first bending portion. The second direction is perpendicular to the first direction.

21. The battery cell according to any one of claims 1-17, characterized in that, There are a plurality of the first pole pieces and a plurality of the second pole pieces, and along the first direction, the first straight portions and the second straight portions are alternately arranged.

22. The battery cell according to any one of claims 1-17, characterized in that, The first pole piece includes a first current collector and a first active material layer, the first active material layer is arranged on the surface of the first current collector, the part of the first current collector located at the first bent portion is the first current collecting portion, the part of the first current collector located at the first straight portion is the third current collecting portion, and the first current collecting portion and the third current collecting portion are integrally formed; and / or, the second pole piece includes a second current collector and a second active material layer, the second active material layer is arranged on the surface of the second current collector, the part of the second current collector located at the second bent portion is the second current collecting portion, the part of the second current collector located at the second straight portion is the fourth current collecting portion, and the second current collecting portion and the fourth current collecting portion are integrally formed.

23. A battery device, characterized in that, The invention comprises a battery cell according to any one of claims 1 to 22.

24. An electrical device, characterized in that, The invention comprises a battery cell according to any one of claims 1 to 22.

25. An electrode assembly, characterized in that, include: A first pole piece, comprising a first bent portion and two first straight portions, wherein the two first straight portions are spaced apart along a first direction, and the first bent portion connects the two first straight portions; A second pole piece, the polarity of the second pole piece is opposite to that of the first pole piece, the second pole piece includes a second bent portion and two second straight portions, the two second straight portions are arranged at intervals along the first direction, the second bent portion connects the two second straight portions, one first straight portion is arranged between the two second straight portions in the second pole piece, and one second straight portion is arranged between the two first straight portions in the first pole piece.

26. The electrode assembly according to claim 25, wherein The first bending portion is connected to one end of the first straight portion along a second direction. Along the second direction, a first insulating layer is provided at one end of the first straight portion away from the first bending portion. The second direction is perpendicular to the first direction.

27. The electrode assembly according to claim 25, wherein, A third insulating layer is provided on a side of the first bent portion facing the second straight portion.

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