Electrode assembly, battery monomer, battery and electric equipment

Abstract

The embodiment of the invention provides an electrode assembly, a battery monomer, a battery and electric equipment, and belongs to the technical field of batteries. The electrode assembly comprises a plurality of structural units, the structural units are stacked in the first direction, and each structural unit comprises a first pole piece and a second pole piece. The first pole piece comprises a bent section and a plurality of straight sections, and every two adjacent straight sections are arranged at intervals in the first direction and connected with one bent section. The polarity of the second pole piece is opposite to that of the first pole piece, and the second pole piece and the straight section are alternately arranged in the first direction. According to the structure, deflection of the electrode assembly in the forming process can be reduced, so that the risk of dislocation between the electrode plates is reduced, and the reliability of the electrode assembly can be effectively improved.

Description

Electrode assemblies, battery cells, batteries and electrical equipment Technical Field

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

[0002] With the development of new energy technology, batteries are used more and more widely, for example, in mobile phones, laptops, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and power tools.

[0003] In battery cells, electrode assemblies are generally classified into two types: laminated and wound. While laminated electrode assemblies offer advantages such as low local internal resistance and high energy density, their reliability still needs to be improved. Therefore, improving the reliability of electrode assemblies is a pressing issue in battery technology.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide an electrode assembly, a battery cell, a battery, and an electrical device, which can effectively improve the reliability of the electrode assembly.

[0006] In a first aspect, an embodiment of the present application provides an electrode assembly, comprising a plurality of structural units, which are stacked along a first direction, and the structural units include a first pole piece and a second pole piece; the first pole piece includes a bent section and a plurality of straight sections, and two adjacent straight sections are spaced apart along the first direction and connected by a bent section; the second pole piece has an opposite polarity to the first pole piece, and the second pole piece and the straight sections are alternately arranged along the first direction.

[0007] In the above technical solution, the electrode assembly includes multiple structural units, and the first pole piece in each structural unit is a folded structure formed by a folded section and a straight section, and the straight section of the first pole piece and the second pole piece are arranged alternately. In this way, during production, the first pole piece and the second pole piece can be first formed into a structural unit, and then the multiple structural units can be stacked together. Therefore, the deflection of the electrode assembly during the forming process can be reduced, thereby reducing the risk of misalignment between the pole pieces, so as to effectively improve the reliability of the electrode assembly.

[0008] In some embodiments, the number of straight sections of the first electrode piece in at least one structural unit is greater than two, thereby increasing the number of straight sections of the first electrode piece in at least one structural unit and effectively improving the production efficiency of the electrode assembly.

[0009] In some embodiments, the number of straight sections of the first electrode piece in at least one structural unit is an odd number. When the number of straight sections in the first electrode piece is an odd number, the number of bent sections in the first electrode piece is an even number, and the number of bent sections on both sides of the structural unit perpendicular to the first direction is equal. When the first electrode piece is subjected to a force in the first direction, the bent sections on both sides of the structural unit can deform, resulting in better structural stability of the first electrode piece, making the structural unit less prone to deflection, reducing the risk of misalignment between the electrode pieces, and improving the reliability of the electrode assembly.

[0010] In some embodiments, the number of straight sections of the first electrode piece in each structural unit is greater than two. This increases the number of straight sections of the first electrode piece in each structural unit. Given a constant dimension of the electrode assembly along the first direction, this helps reduce the number of structural units in the electrode assembly, further improving the production efficiency of the electrode assembly.

[0011] In some embodiments, the number of straight sections of the first electrode piece in each structural unit is an odd number. Thus, the number of bent sections in each first electrode piece is an even number, and the number of bent sections on both sides of each structural unit perpendicular to the first direction is equal. When the first electrode piece is subjected to a force in the first direction, the bent sections on both sides of the structural unit can deform, so that the first electrode piece in each structural unit has good structural stability, further reducing the risk of structural unit deflection, thereby reducing the risk of electrode assembly deflection.

[0012] In some embodiments, the number of straight sections of the first electrode piece in each structural unit is three. This can reduce the risk of the first electrode piece tilting during folding and ensure better stability after forming the first electrode piece in the structural unit, reducing the risk of electrode assembly deflection.

[0013] In some embodiments, the number of straight segments of the first electrode pieces in at least two structural units is different. This allows for a variety of structural unit types in the electrode assembly, allowing for multiple structural units to be combined in a variety of ways, increasing the versatility of the electrode assembly and adapting to market demands to a greater extent.

[0014] In some embodiments, the plurality of structural units include a first structural unit, a second structural unit, and a third structural unit sequentially arranged along a first direction; wherein the number of straight sections of the first pole piece in the first structural unit and the number of straight sections of the first pole piece in the third structural unit are both even numbers, and the number of straight sections of the first pole piece in the second structural unit is odd number. The number of straight sections of the second structural unit located in the middle is odd number, and the number of straight sections of the first structural unit and the third structural unit located on both sides of the second structural unit are even number. The number of bent sections of the second structural unit on both sides perpendicular to the first direction is equal. When the combined structure formed by the first structural unit, the second structural unit, and the third structural unit is subjected to a force along the first direction, the difference in the amount of deformation of the combined structure on both sides perpendicular to the first direction is small, and the combined structure has better structural stability and is not easily deflected.

[0015] In some embodiments, along a first direction, the two straight sections at the ends of the first electrode sheet are respectively the first straight section and the second straight section; in two adjacent structural units, the first straight section of one structural unit and the second straight section of the other structural unit are adjacent straight sections; along a second direction, the end of the first straight section of one structural unit away from the bent section and the end of the second straight section of the other structural unit away from the bent section are respectively located on opposite sides of the electrode assembly, with the second direction being perpendicular to the first direction. In this way, the adjacent bent sections on each side of the electrode assembly in the second direction are neither too far apart nor too close, resulting in a more reasonable layout, better structural stability for the electrode assembly, and further reducing the risk of deflection.

[0016] In some embodiments, in a structural unit, the number of straight segments of the first electrode piece is equal to the number of second electrode pieces. This way, the straight segments in a structural unit correspond one-to-one with the second electrode pieces, and the straight segments and second electrode pieces in two adjacent structural units can be alternately arranged, which is beneficial for increasing the capacity of the battery cell.

[0017] In some embodiments, the electrode assembly further includes a third electrode sheet having the same polarity as the first electrode sheet. Along the first direction, the third electrode sheet is disposed on at least one side of the plurality of structural units, and the third electrode sheet is adjacent to the second electrode sheet of an adjacent structural unit. This fully utilizes the outermost second electrode sheet of the structural unit at the end of the electrode assembly, thereby increasing the capacity of the battery cell.

[0018] In some embodiments, the first electrode is a negative electrode and the second electrode is a positive electrode. This makes it easier to cover the positive electrode with the negative electrode, reduces the risk of the positive electrode extending beyond the negative electrode, and improves the reliability of the electrode assembly.

[0019] In some embodiments, each straight segment is provided with a first tab, and the multiple first tabs in each structural unit are aligned along a first direction; and / or each second pole piece is provided with a second tab, each structural unit includes multiple second pole pieces, and the multiple second tabs in each structural unit are aligned along the first direction. If the multiple first tabs in a structural unit are aligned along the first direction, bus connection is facilitated, and when cutting the first tabs, the structural unit can be cut as a whole, thereby improving the efficiency of cutting the first tabs and improving production efficiency. If the multiple second tabs in a structural unit are aligned along the first direction, bus connection is facilitated, and when cutting the second tabs, the structural unit can be cut as a whole, thereby improving the efficiency of cutting the second tabs and improving production efficiency.

[0020] In some embodiments, the structural unit further includes an isolation membrane, to which the first and second pole pieces are both composited, and the isolation membrane is configured to separate the first and second pole pieces. The isolation membrane provides insulation isolation between the first and second pole pieces, reducing the risk of internal short circuits in the electrode assembly. The first and second pole pieces are both composited with the isolation membrane, thereby ensuring good integrity among the first and second pole pieces and the isolation membrane in the structural unit, and reducing the risk of misalignment between the first and second pole pieces.

[0021] In some embodiments, the bending section is provided with a guide configured to guide the bending section. The guide enables the first electrode piece to bend at a specified position, thereby improving the folding efficiency of the first electrode piece, achieving higher consistency in the folding position, and more accurately aligning the relative position of the straight section and the second electrode piece, thereby ensuring greater reliability of the electrode assembly.

[0022] In some embodiments, the guide portion includes a groove disposed in the bend section. The bend section is weaker in the region where the groove is disposed. The groove provides a good guiding effect, making it easier for the first pole piece to bend at the groove location to form the corresponding bend section. This guide portion has a simple structure and is easy to form.

[0023] In some embodiments, the bent section includes a current collector and two active material layers, the two active material layers being disposed on either side of the current collector, and at least one of the active material layers being provided with a groove. Providing a groove in at least one of the active material layers of the bent section allows for localized thinning and weakening of the bent section, which is simple to implement.

[0024] In some embodiments, a layer of active material is provided with grooves, which can reduce the difficulty of forming the first pole piece.

[0025] In some embodiments, both active material layers are provided with grooves, so that the bending section is weaker in the area where the grooves are provided and is easier to bend.

[0026] In some embodiments, the guide portion further includes a through hole extending through the current collector, and the region of the current collector corresponding to the groove forms an inactive material layer region, and the through hole is provided in the inactive material layer region. The provision of the through hole reduces the stiffness of the inactive material layer region of the current collector, thereby enhancing the folding effect by reducing the stiffness of the inactive material layer region and further improving the folding efficiency of the first pole piece. In addition, in the battery cell, the electrolyte can flow between the first pole piece and the second pole piece through the through hole, which is conducive to the electrolyte infiltration of the pole pieces.

[0027] In some embodiments, the inactive material layer region is provided with a plurality of through holes, which are spaced apart along the width direction of the first electrode piece. This further reduces the stiffness of the current collector in the inactive material layer region, making it easier for the first electrode piece to bend in the inactive material layer region.

[0028] In some embodiments, the groove extends along the width direction of the first electrode piece and penetrates the active material layer. The groove of this structure is easier to form, and the first electrode piece is easier to bend in the area of ​​the groove.

[0029] In some embodiments, the active material layer is provided with a plurality of grooves, and the plurality of grooves are spaced apart along the width direction of the first electrode piece. In this way, the first electrode piece has good bending performance in the region of the plurality of grooves, and the first electrode piece has sufficient strength in this region, and is not prone to the risk of fracture.

[0030] In some embodiments, the bending section includes a current collector and two active material layers, with the two active material layers disposed on either side of the current collector. The guide portion includes a through-hole disposed in the bending section; the through-hole extends through the current collector and the two active material layers; or, the through-hole extends through the current collector, with the two active material layers covering the through-hole. The area of ​​the bending section where the through-hole is located has reduced rigidity, making it easier for the first pole piece to bend at the location of the through-hole, thereby forming the corresponding bending section. If the through-hole extends through the current collector and the two active material layers, the first pole piece exhibits improved bending performance in the area where the through-hole is located. Furthermore, in a battery cell, electrolyte can flow between the first and second pole pieces through the through-hole, facilitating electrolyte wetting of the pole pieces. If the through-hole extends through the current collector and the two active material layers cover the through-hole, the first pole piece has sufficient strength in the area where the through-hole is located, reducing the risk of fracture during bending. Furthermore, when forming the first pole piece, the through-hole can be machined into the current collector first, followed by the active material layer disposed on the surface of the current collector, so that the active material layer covers the through-hole, thereby reducing the difficulty of forming the first pole piece.

[0031] In some embodiments, the guide portion includes a plurality of through holes, which are spaced apart along the width direction of the first pole piece. This further reduces the rigidity of the region where the through holes are located in the bending section, making it easier for the first pole piece to bend in the region where the through holes are located.

[0032] In some embodiments, the through hole is a rectangular hole. Such a through hole has a simple structure and is easy to form.

[0033] In some embodiments, the cross section of the through hole is rectangular, and the length direction of the rectangle is consistent with the width direction of the first pole piece, so that the folding position of the first pole piece is more accurate.

[0034] In some embodiments, the length of the rectangle is a and the width is b, satisfying: 10≤a / b≤400. When a / b<10, the size of the through hole in the bending direction of the bending section is large, and the folding consistency of the first pole piece in the through hole area is poor, affecting the folding accuracy of the first pole piece; when a / b>400, the size of the through hole in the bending direction of the bending section is small, and the ability of the through hole to guide the bending of the first pole piece is weak, which also affects the folding accuracy of the first pole piece. Therefore, 10≤a / b≤400 makes the through hole a slender structure extending along the width direction of the first pole piece, improving the consistency of the folding position of the first pole piece, making the folding position of the first pole piece more accurate, and improving the folding efficiency of the first pole piece.

[0035] In some embodiments, 20≤a / b≤100, thereby further improving the folding efficiency of the first pole piece.

[0036] In some embodiments, 3 mm ≤ a ≤ 20 mm; and / or, 0.05 mm ≤ b ≤ 0.3 mm.

[0037] In a second aspect, an embodiment of the present application provides a battery cell, comprising a housing and an electrode assembly provided by any one embodiment of the first aspect, wherein the electrode assembly is accommodated in the housing.

[0038] In a third aspect, an embodiment of the present application provides a battery, comprising a battery cell provided by any embodiment of the second aspect.

[0039] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising a battery cell provided by any one embodiment of the second aspect, wherein the battery cell is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0041] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0042] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0043] FIG3 is an exploded view of a battery cell provided in some embodiments of the present application;

[0044] FIG4 is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application;

[0045] FIG5 is a schematic structural diagram of an electrode assembly provided in yet other embodiments of the present application;

[0046] FIG6 is a schematic structural diagram of an electrode assembly provided in some further embodiments of the present application;

[0047] FIG7 is a schematic structural diagram of an electrode assembly provided in some other embodiments of the present application;

[0048] FIG8 is an axonometric view of an electrode assembly provided in some embodiments of the present application;

[0049] FIG9 is an axonometric view of the structural unit shown in FIG8 ;

[0050] FIG10 is a schematic structural diagram of the structural unit shown in FIG9 after expansion;

[0051] FIG11 is an axonometric view of a first pole piece provided in some embodiments of the present application;

[0052] FIG12 is a schematic structural diagram of a first pole piece provided in some embodiments of the present application;

[0053] FIG13 is a partial view of the first pole piece shown in FIG12 after unfolding;

[0054] FIG14 is a top view of the first pole piece shown in FIG13 ;

[0055] FIG15 is a schematic structural diagram of a first pole piece provided in yet other embodiments of the present application;

[0056] FIG16 is a partial view of the first pole piece shown in FIG15 after unfolding;

[0057] FIG17 is a partial view of an unfolded first pole piece provided in some other embodiments of the present application;

[0058] FIG18 is a top view of the first pole piece shown in FIG17 ;

[0059] FIG19 is a top view of an unfolded first pole piece provided in some embodiments of the present application;

[0060] FIG20 is a top view of an unfolded first pole piece provided in some other embodiments of the present application;

[0061] FIG21 is a partial view of an unfolded first pole piece provided in other embodiments of the present application;

[0062] FIG22 is a top view of the first pole piece shown in FIG21 ;

[0063] FIG23 is a partial view of an unfolded first pole piece provided in some other embodiments of the present application;

[0064] FIG24 is a top view of the current collector shown in FIG23;

[0065] FIG25 is a partial enlarged view of point A in FIG18;

[0066] FIG26 is a partial enlarged view of point B in FIG22 .

[0067] Icons: 1-housing; 11-housing; 12-end cap; 2-electrode assembly; 21-positive electrode ear; 22-negative electrode ear; 23-structural unit; 23a-first structural unit; 23b-second structural unit; 23c-third structural unit; 231-first pole piece; 2311-straight section; 2311a-first straight section; 2311b-second straight section; 2312-bent section; 23121-guide portion; 23122-groove; 23123-current collector; 23124-active material layer; 231 25-inactive material layer area; 23126-through hole; 2313-first pole piece; 232-second pole piece; 2321-second pole piece; 233-isolation membrane; 234-third pole piece; 3-positive electrode terminal; 4-negative electrode terminal; 10-battery cell; 20-housing; 201-first part; 202-second part; 100-battery; 200-controller; 300-motor; 1000-vehicle; W-bending direction; X-first direction; Y-second direction; Z-width direction of the first pole piece. DETAILED DESCRIPTION

[0068] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0069] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0070] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0071] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0072] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0073] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0074] The term "plurality" used in this application refers to two or more (including two).

[0075] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0076] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0077] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0078] In some embodiments, the positive electrode may be a positive electrode sheet, which 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.

[0079] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0080] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel 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 (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.).

[0081] 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 traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4 (also referred to 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 iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. 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 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0082] In some embodiments, a positive electrode may be a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam, among others. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not be provided with a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0083] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0084] As an example, the negative electrode current collector can be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium can be used. The metal foam can be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (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.).

[0085] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0086] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0087] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells that is well known in the art. As an example, the negative electrode 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, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0088] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0089] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0090] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0091] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0092] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. The electrolyte can be liquid, gel, or solid.

[0093] The liquid electrolyte includes an electrolyte salt and a solvent.

[0094] In some embodiments, the electrolyte salt may be selected from 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 difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0095] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be an ether solvent. Ether solvents can 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.

[0096] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0097] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0098] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0099] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0100] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0101] In some embodiments, the electrode assembly is a laminate structure.

[0102] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0103] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0104] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0105] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0106] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0107] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0108] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0109] 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, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery, etc. There is no special limitation in this application.

[0110] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0111] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0112] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0113] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0114] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0115] In battery cells, electrode assemblies are generally classified into two types: laminated and wound. A typical laminated electrode assembly may include a first electrode sheet and multiple second electrode sheets, with the first and second electrode sheets having opposite polarities. The first electrode sheet is folded back and forth, alternating between the straight segments formed by the folding of the first electrode sheet and the second electrode sheets. During the electrode assembly forming process, as the number of straight segments in the first electrode sheet increases, the electrode assembly is prone to skew, causing misalignment between the electrode sheets and resulting in poor reliability.

[0116] In view of this, an embodiment of the present application provides an electrode assembly comprising a plurality of structural units, the plurality of structural units being stacked. The structural units include a first electrode piece and a second electrode piece of opposite polarity. The first electrode piece includes a bent segment and a plurality of straight segments, with two adjacent straight segments spaced apart along a first direction and connected to a bent segment. The second electrode pieces and the straight segments are arranged alternately along the stacking direction of the plurality of structural units.

[0117] In such an electrode assembly, the electrode assembly is divided into multiple structural units, which reduces the number of layers of the straight section of the first electrode piece in the structural unit and reduces the risk of structural unit deflection. During production, the first and second electrode pieces can be formed into a structural unit, and then the multiple structural units can be stacked together. This can reduce the risk of electrode assembly deflection during the forming process, thereby reducing the risk of misalignment between electrode pieces and effectively improving the reliability of the electrode assembly.

[0118] The electrode assembly described in the embodiments of the present application is applicable to battery cells, batteries, and electrical equipment using battery cells.

[0119] Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. Vehicles can be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0120] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0121] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is disposed within vehicle 1000. Battery 100 can be located at the bottom, front, or rear of vehicle 1000. Battery 100 can be used to power vehicle 1000, for example, as an operating power source for vehicle 1000.

[0122] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0123] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve 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.

[0124] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a battery cell 10 and a housing 20, wherein the housing 20 accommodates the battery cell 10.

[0125] The housing 20 is a component that houses the battery cells 10 and provides a storage space for the battery cells 10. The housing 20 can have various structures. In some embodiments, the housing 20 can include a first portion 201 and a second portion 202, which overlap to define a storage space for the battery cells 10. The first portion 201 and the second portion 202 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first portion 201 can be a hollow structure with one side open, and the second portion 202 can also be a hollow structure with one side open. The open side of the second portion 202 overlaps the open side of the first portion 201, forming the housing 20 with a storage space. Alternatively, the first portion 201 can be a hollow structure with one side open, and the second portion 202 can be a plate-like structure. The second portion 202 overlaps the open side of the first portion 201, forming the housing 20 with a storage space. The first portion 201 and the second portion 202 can be sealed by a sealing element, which can be a sealing ring, sealant, etc.

[0126] In the battery 100, there can be one or more battery cells 10. If there are multiple battery cells 10, the multiple battery cells 10 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 10. Multiple battery cells 10 can be connected in series, parallel, or in a hybrid connection to form a battery module, which can then be connected in series, parallel, or in a hybrid connection to form a single unit and housed within the housing 20. Alternatively, all battery cells 10 can be directly connected in series, parallel, or in a hybrid connection, and then the entire unit formed by all battery cells 10 can be housed within the housing 20.

[0127] Please refer to Figure 3, which is an exploded view of a battery cell 10 provided in some embodiments of the present application. The battery cell 10 may include a housing 1 and an electrode assembly 2, wherein the electrode assembly 2 is accommodated in the housing 1.

[0128] The housing 1 is a component for accommodating the electrode assembly 2 and electrolyte, etc. As an example, the housing 1 may include a shell 11 and an end cap 12. The electrolyte may be an electrolyte solution.

[0129] The housing 11 may be a hollow structure with an opening at one end, or may be a hollow structure with openings at opposite ends. The housing 11 may have various shapes, such as a cylinder or a rectangular parallelepiped. The housing 11 may be made of various materials, such as copper, iron, aluminum, steel, and aluminum alloys.

[0130] The end cap 12 is a component that closes the opening of the shell 11 to isolate the internal environment of the battery cell 10 from the external environment. The end cap 12 and the shell 11 together define a receiving space for accommodating the electrode assembly 2, electrolyte and other components. The end cap 12 can be connected to the shell 11 by welding or rolling to close the opening of the shell 11. The shape of the end cap 12 can be adapted to the shape of the shell 1. For example, the shell 11 is a rectangular parallelepiped structure, and the end cap 12 is a rectangular plate structure adapted to the shell 1. For another example, the shell 11 is a cylindrical structure, and the end cap 12 is a circular plate structure adapted to the shell 11. The material of the end cap 12 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 12 and the shell 11 can be the same or different.

[0131] In an embodiment where the housing 11 is open at one end, one end cap 12 may be provided. In an embodiment where the housing 11 is open at two opposite ends, two end caps 12 may be provided, each of which closes the two openings of the housing 11, and the two end caps 12 and the housing 11 together define a receiving space.

[0132] In some embodiments, the battery cell 10 may further include electrode terminals, which are disposed on the outer casing 1 and are used to electrically connect to the tabs of the electrode assembly 2 to output electrical energy from the battery cell 10. The electrode terminals may be disposed on the shell 11 of the outer casing 1 or on the end cap 12 of the outer casing 1. The electrode terminals may be directly connected to the tabs, for example, by direct welding. The electrode terminals may also be indirectly connected to the tabs, for example, by indirect connection via a current collecting member. The current collecting member may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0133] As an example, as shown in FIG3 , an opening is formed at one end of the housing 11, and there is only one end cap 12 in the outer shell 1, and each end cap 12 closes the opening of the housing 11. Two electrode terminals are provided on the end cap 12, namely a positive electrode terminal 3 and a negative electrode terminal 4. A positive electrode tab 21 and a negative electrode tab 22 are formed on the end of the electrode assembly 2 facing the end cap 12. The positive electrode terminal 3 is electrically connected to the positive electrode tab 21, and the negative electrode terminal 4 is electrically connected to the negative electrode tab 22.

[0134] Please refer to Figure 4, which is a schematic diagram of the structure of an electrode assembly 2 provided in some embodiments of the present application. In the first aspect, the embodiments of the present application provide an electrode assembly 2, which includes a plurality of structural units 23, wherein the plurality of structural units 23 are stacked along a first direction X, and the structural units 23 include a first electrode piece 231 and a second electrode piece 232. The first electrode piece 231 includes a bent section 2312 and a plurality of straight sections 2311, wherein two adjacent straight sections 2311 are spaced apart along the first direction X, and two adjacent straight sections 2311 are connected to a bent section 2312. The second electrode piece 232 has an opposite polarity to the first electrode piece 231, and along the first direction X, the second electrode piece 232 and the straight section 2311 are alternately arranged.

[0135] The electrode assembly 2 may include two, three, four, five, or more structural units 23. The first electrode piece 231 and the second electrode piece 232 in the structural unit 23 have opposite polarities. Alternatively, the first electrode piece 231 may be a positive electrode piece and the second electrode piece 232 may be a negative electrode piece, or the first electrode piece 231 may be a negative electrode piece and the second electrode piece 232 may be a positive electrode piece. As an example, the electrode assembly 2 may include three or more structural units 23.

[0136] Among them, the first pole piece 231 is a folding structure, and the first pole piece 231 is folded to form a bent section 2312 and multiple straight sections 2311. The straight section 2311 is the straight portion of the first pole piece 231 that is not bent. The thickness direction of the straight section 2311 is consistent with the first direction X, and the multiple straight sections 2311 of the first pole piece 231 are arranged along the first direction X. The straight sections 2311 in the first pole piece 231 can be two, three, four, five or more. Of course, the straight sections 2311 in the first pole piece 231 can be an odd number or an even number. For two adjacent structural units 23, the straight sections 2311 can be equal or unequal. The bent section 2312 is the portion where the first pole piece 231 is bent, and the bent section 2312 connects two adjacent straight sections 2311. Along the second direction Y, the bent section 2312 is connected to the end of the straight section 2311, and the second direction Y is perpendicular to the first direction X. The bent section 2312 can be arc-shaped, and the bending direction W of the bent section 2312 is the extension direction of the arc in which the bent section 2312 is located. The bent section 2312 in the first pole piece 231 can be one or more. It can be understood that the straight section 2311 of the first pole piece 231 has one more bent section 2312 than the bent section 2312. If the number of straight sections 2311 in the first pole piece 231 is an odd number, the number of bent sections 2312 in the first pole piece 231 is an even number. If the number of straight sections 2311 in the first pole piece 231 is an even number, the number of bent sections 2312 in the first pole piece 231 is an odd number. In some embodiments, the number of straight segments 2311 in the first pole piece 231 is 2-20, and further, the number of straight segments 2311 in the first pole piece 231 is 3-9. This can reduce the risk of the first pole piece 231 tilting during folding and ensure that the first pole piece 231 in the structural unit 23 has better stability after being formed.

[0137] The second pole piece 232 can be a straight sheet-like structure, and the thickness direction of the second pole piece 232 is consistent with the first direction X. In the structural unit 23, there can be one or more second pole pieces 232. The second pole piece 232 can have one more or one less second pole piece 232 than the straight section 2311 of the first pole piece 231. The number of second pole pieces 232 can also be equal to the number of straight sections 2311 of the first pole piece 231. If there are multiple second pole pieces 232 in the structural unit 23, the multiple second pole pieces 232 are arranged along the first direction X.

[0138] In the structural unit 23, the second pole pieces 232 and the straight sections 2311 are alternately arranged. Taking the case where the number of second pole pieces 232 in the structural unit 23 is equal to the number of straight sections 2311, and both are three, as an example, the arrangement can be straight section 2311-second pole piece 232-straight section 2311-second pole piece 232-straight section 2311-second pole piece 232.

[0139] It should be noted that the alternating arrangement of the second pole piece 232 and the straight section 2311 only indicates that the second pole piece 232 and the straight section 2311 are arranged in an alternating manner, and does not limit the provision of other components between the second pole piece 232 and the straight section 2311. Other components may be provided between the second pole piece 232 and the straight section 2311. For example, the structural unit 23 further includes an isolation membrane 233, and the second pole piece 232 is separated from the first pole piece 231 by the isolation membrane 233 to achieve insulation isolation between the second pole piece 232 and the first pole piece 231. In this case, the isolation membrane 233 is provided between the second pole piece 232 and the straight section 2311 of the first pole piece 231.

[0140] In the embodiment of the present application, the electrode assembly 2 is divided into multiple structural units 23, which reduces the number of layers of the straight sections 2311 of the first electrode piece 231 in the structural unit 23, thereby reducing the risk of deflection of the structural unit 23. During production, the first electrode piece 231 and the second electrode piece 232 can be first formed into the structural unit 23, and then the multiple structural units 23 can be stacked together. This can reduce the risk of deflection of the electrode assembly 2 during the forming process, thereby reducing the risk of misalignment between the electrode pieces, and effectively improving the reliability of the electrode assembly 2.

[0141] In some embodiments, referring to FIG. 4 , the number of the straight sections 2311 of the first pole piece 231 in at least one structural unit 23 is greater than two.

[0142] The number of straight segments 2311 in one structural unit 23 may be greater than two, or the number of straight segments 2311 in multiple structural units 23 may be greater than two. The number of straight segments 2311 in some structural units 23 may be greater than two, or the number of straight segments 2311 in all structural units 23 may be greater than two.

[0143] Taking the case where there are three structural units 23 in the electrode assembly 2 as an example, the number of straight segments 2311 in the three structural units 23 may be greater than two; the number of straight segments 2311 in two structural units 23 may be greater than two, and the number of straight segments 2311 in the other structural unit 23 may be two; as shown in Figure 4, the number of straight segments 2311 in two structural units 23 may be two, and the number of straight segments 2311 in the other structural unit 23 may be greater than two.

[0144] In this embodiment, the number of straight sections 2311 in at least one structural unit 23 is greater than two, so that at least one structural unit 23 has more straight sections 2311, which can effectively improve the production efficiency of the electrode assembly 2. For example, when cutting the tabs from the first electrode piece 231 in the structural unit 23, more straight sections 2311 in the first electrode piece 231 can be used to cut more tabs at a time, thereby improving the production efficiency of the electrode assembly 2.

[0145] In some embodiments, referring to FIG. 4 , the number of the straight segments 2311 of the first pole piece 231 in at least one structural unit 23 is an odd number.

[0146] In the structural unit 23 having an odd number of straight sections 2311 , the straight sections 2311 may be three, five, seven or more.

[0147] The number of straight segments 2311 in one structural unit 23 may be an odd number, or the number of straight segments 2311 in multiple structural units 23 may be an odd number, or the number of straight segments 2311 in some structural units 23 may be an odd number, or the number of straight segments 2311 in all structural units 23 may be an odd number.

[0148] Taking the case where there are three structural units 23 in the electrode assembly 2 as an example, the number of straight segments 2311 in the three structural units 23 may be an odd number; the number of straight segments 2311 in two structural units 23 may be an odd number, and the number of straight segments 2311 in the other structural unit 23 may be an even number; as shown in Figure 4, the number of straight segments 2311 in two structural units 23 may be an even number, and the number of straight segments 2311 in the other structural unit 23 may be an odd number.

[0149] When the number of straight sections 2311 in the first pole piece 231 is an odd number, the number of bent sections 2312 in the first pole piece 231 is an even number, and the number of bent sections 2312 on both sides of the structural unit 23 in the second direction Y is equal. When the first pole piece 231 is subjected to a force along the first direction X, the bent sections 2312 on both sides of the structural unit 23 can be deformed. The structural stability of the first pole piece 231 is better, and the difference in deformation on both sides of the structural unit 23 is reduced. The structural unit 23 is less likely to be skewed, which reduces the risk of misalignment between the pole pieces and improves the reliability of the electrode assembly 2.

[0150] In some embodiments, please refer to Figure 5, which is a schematic structural diagram of an electrode assembly 2 provided in some other embodiments of the present application. The number of straight sections 2311 of the first electrode piece 231 in each structural unit 23 is greater than two.

[0151] In this embodiment, the number of straight segments 2311 in the structural unit 23 can be an odd number or an even number, and the number of straight segments 2311 in two adjacent structural units 23 can be equal or unequal.

[0152] In this embodiment, the number of straight sections 2311 of the first pole piece 231 of each structural unit 23 is greater than two, so that there are more straight sections 2311 of the first pole piece 231 in each structural unit 23. When the size of the electrode assembly 2 along the first direction X is constant, it is beneficial to reduce the number of structural units 23 of the electrode assembly 2, and can further improve the production efficiency of the electrode assembly 2.

[0153] In some embodiments, referring to FIG. 5 , the number of the straight segments 2311 of the first pole piece 231 in each structural unit 23 is an odd number.

[0154] In the structural unit 23, there may be three, five, seven or more straight sections 2311. The straight sections 2311 in two adjacent structural units 23 may be equal or unequal.

[0155] In this embodiment, the number of straight sections 2311 of the first pole piece 231 of each structural unit 23 is an odd number. In this way, the number of bent sections 2312 in each first pole piece 231 is an even number, and the number of bent sections 2312 on both sides perpendicular to the first direction X (second direction Y) in each structural unit 23 is equal. When the first pole piece 231 is subjected to a force along the first direction X, the bent sections 2312 on both sides of the structural unit 23 can be deformed, reducing the difference in deformation amount on both sides of the structural unit 23, so that the first pole piece 231 in each structural unit 23 has better structural stability, further reducing the risk of deflection of the structural unit 23, thereby reducing the risk of deflection of the electrode assembly 2.

[0156] In some embodiments, referring to FIG. 5 , the number of the straight sections 2311 of the first pole piece 231 in each structural unit 23 is three.

[0157] Excessive straight sections 2311 in the structural unit 23 increase the risk of the first pole piece 231 tilting during folding. Providing three straight sections 2311 in each structural unit 23 can reduce the risk of the first pole piece 231 tilting during folding and ensure better stability after forming the first pole piece 231 in the structural unit 23, thereby reducing the risk of the electrode assembly 2 tilting.

[0158] In some embodiments, the numbers of straight segments 2311 of the first pole pieces 231 in at least two structural units 23 are different.

[0159] The number of straight sections 2311 of the first pole pieces 231 in the n structural units 23 is different, n≥2. It can be understood that the number of straight sections 2311 of the first pole pieces 231 in any two structural units 23 in the n structural units 23 is different. Taking n=3 as an example, that is, the number of straight sections 2311 of the first pole pieces 231 in the three structural units 23 is different, it can be understood that the number of straight sections 2311 of the first pole pieces 231 in any two structural units 23 in the three structural units 23 is different. For example, the straight sections 2311 of the first pole piece 231 of one structural unit 23 is two, the straight sections 2311 of the first pole piece 231 of another structural unit 23 is three, and the straight sections 2311 of the first pole piece 231 of yet another structural unit 23 is four.

[0160] In this embodiment, the structural units 23 in the electrode assembly 2 are of various types, and multiple structural units 23 can be combined in various ways to improve the variability of the electrode assembly 2 and adapt to market demand to a greater extent.

[0161] In some embodiments, please refer to FIG6 , which is a schematic diagram of the structure of the electrode assembly 2 provided in some other embodiments of the present application. The plurality of structural units 23 include a first structural unit 23a, a second structural unit 23b, and a third structural unit 23c arranged sequentially along the first direction X. The number of straight sections 2311 of the first electrode piece 231 in the first structural unit 23a and the number of straight sections 2311 of the first electrode piece 231 in the third structural unit 23c are both even numbers, and the number of straight sections 2311 of the first electrode piece 231 in the second structural unit 23b is an odd number.

[0162] The first structural unit 23a, the second structural unit 23b, and the third structural unit 23c are three adjacent structural units 23 among the multiple structural units 23. The number of structural units 23 in the electrode assembly 2 can be three, and the three structural units 23 are respectively located in the first structural unit 23a, the second structural unit 23b, and the third structural unit 23c; the number of structural units 23 in the electrode assembly 2 can be greater than three, wherein the three consecutive structural units 23 are respectively the first structural unit 23a, the second structural unit 23b, and the third structural unit 23c.

[0163] The number of straight segments 2311 in the first structural unit 23a and the number of straight segments 2311 in the third structural unit 23c are both even numbers, such as two, four, six, eight, or more. The number of straight segments 2311 in the first structural unit 23a and the number of straight segments 2311 in the third structural unit 23c can be equal or different. The number of straight segments 2311 in the second structural unit 23b is an odd number, such as three, five, seven, nine, or more.

[0164] As an example, as shown in Figure 6, the first structural unit 23a and the third structural unit 23c each have two straight sections 2311, and the second structural unit 23b has three straight sections 2311. The first pole piece 231 in the first structural unit 23a and the first pole piece 231 in the third structural unit 23c are generally U-shaped, and the first pole piece 231 in the second structural unit 23b is generally S-shaped.

[0165] In this embodiment, the number of straight sections 2311 of the second structural unit 23b located in the middle is an odd number, and the number of straight sections 2311 of the first structural unit 23a and the third structural unit 23c located on both sides of the second structural unit 23b are an even number. The number of bent sections 2312 on both sides of the second structural unit 23b perpendicular to the first direction X (second direction Y) is equal. When the combined structure formed by the first structural unit 23a, the second structural unit 23b, and the third structural unit 23c is subjected to a force along the first direction X, the difference in deformation of the combined structure on both sides perpendicular to the first direction X is small. The combined structure has better structural stability and is not easy to deflect.

[0166] In some embodiments, referring to Figures 4-6, along the first direction X, the two straight sections 2311 at both ends of the first electrode piece 231 are respectively a first straight section 2311a and a second straight section 2311b. In two adjacent structural units 23, the first straight section 2311a of one structural unit 23 and the second straight section 2311b of the other structural unit 23 are two adjacent straight sections 2311. Along the second direction Y, the end of the first straight section 2311a of one structural unit 23 away from the bent section 2312 and the end of the second straight section 2311b of the other structural unit 23 away from the bent section 2312 are respectively located on opposite sides of the electrode assembly 2. The second direction Y is perpendicular to the first direction X.

[0167] The first direction X, the second direction Y and the width direction Z of the first pole piece are perpendicular to each other.

[0168] The first straight section 2311a and the second straight section 2311b are respectively the straight sections 2311 at the two ends of the first electrode piece 231 along the first direction X. It is understandable that if there are two straight sections 2311 in the first electrode piece 231, the two straight sections 2311 are respectively the first straight section 2311a and the second straight section 2311b. Along the second direction Y, the end of the first straight section 2311a of one structural unit 23 away from the bent section 2312 and the end of the second straight section 2311b of another structural unit 23 away from the bent section 2312 are respectively located on both sides of the electrode assembly 2. It is understandable that the bent section 2312 connected to the first straight section 2311a of one structural unit 23 and the bent section 2312 connected to the second straight section 2311b of another structural unit 23 are respectively located on both sides of the electrode assembly 2.

[0169] In two adjacent structural units 23 , a second pole piece 232 may be provided between the first straight section 2311 a of one structural unit 23 and the second straight section 2311 b of the other structural unit 23 .

[0170] Taking the embodiment shown in FIG6 as an example, the first structural unit 23a and the second structural unit 23b are two adjacent structural units 23. Along the second direction Y, an end of the first straight section 2311a of the first structural unit 23a away from the bent section 2312 and an end of the second straight section 2311b of the second structural unit 23b away from the bent section 2312 are respectively located on opposite sides of the electrode assembly 2. Similarly, the second structural unit 23b and the third structural unit 23c are two adjacent structural units 23. Along the second direction Y, an end of the first straight section 2311a of the second structural unit 23b away from the bent section 2312 and an end of the second straight section 2311b of the third structural unit 23c away from the bent section 2312 are respectively located on opposite sides of the electrode assembly 2.

[0171] In this embodiment, the two adjacent bending sections on each side of the electrode assembly 2 in the second direction Y are neither too far nor too close, and the layout is more reasonable, so that the electrode assembly 2 has better structural stability and further reduces the risk of deflection.

[0172] In some embodiments, referring to FIG. 4 to FIG. 6 , in the structural unit 23 , the number of the straight sections 2311 of the first pole piece 231 is equal to the number of the second pole piece 232 .

[0173] Taking the embodiment shown in FIG6 as an example, the first structural unit 23a has two straight sections 2311 and two second pole pieces 232, the second structural unit 23b has three straight sections 2311 and two second pole pieces 232, and the third structural unit 23c has two straight sections 2311 and two second pole pieces 232. In this way, a second pole piece 232 is provided between the first straight section 2311a of the first structural unit 23a and the second straight section 2311b of the second structural unit 23b, and a second pole piece 232 is also provided between the first straight section 2311a of the second structural unit 23b and the second straight section 2311b of the third structural unit 23c.

[0174] In this embodiment, the straight sections 2311 in the structural units 23 correspond one-to-one to the second pole pieces 232, and the straight sections 2311 and the second pole pieces 232 in two adjacent structural units 23 can be alternately arranged, so that in the two adjacent structural units 23, along the first direction X, the pole piece at the top of a structural unit 23 located at the bottom and the pole piece at the bottom of a structural unit 23 located at the top have opposite polarities, so that the straight sections 2311 and the second pole pieces 232 of the two adjacent structural units 23 are fully utilized, which is beneficial to improving the capacitance of the battery cell 10.

[0175] In some embodiments, please refer to FIG. 7 , which is a schematic diagram of the structure of an electrode assembly 2 provided in other embodiments of the present application. The electrode assembly 2 further includes a third electrode piece 234 , which has the same polarity as the first electrode piece 231 . Along the first direction X, the third electrode piece 234 is provided on at least one side of the plurality of structural units 23 , and the third electrode piece 234 is adjacent to the second electrode piece 232 of the adjacent structural unit 23 .

[0176] The third electrode piece 234 can be a flat sheet structure, and the thickness direction of the third electrode piece 234 is consistent with the first direction X. Since the third electrode piece 234 has the same polarity as the first electrode piece 231, the third electrode piece 234 has an opposite polarity to the second electrode piece 232. It is understandable that if the second electrode piece 232 is a negative electrode piece, the third electrode piece 234 is a positive electrode piece; if the second electrode piece 232 is a positive electrode piece, the third electrode piece 234 is a negative electrode piece.

[0177] In the electrode assembly 2, there can be one or two third pole pieces 234. Along the first direction X, if the third pole piece 234 is provided on only one side of multiple structural units 23, there will be only one third pole piece 234 in the electrode assembly 2, and this third pole piece 234 will be the outermost pole piece of the electrode assembly 2 along the first direction X. Along the first direction X, if the third pole piece 234 is provided on both sides of multiple structural units 23, there will be two third pole pieces 234 in the electrode assembly 2, and all structural units 23 will be located between the two third pole pieces 234. The two third pole pieces 234 will be the outermost pole pieces of the electrode assembly 2 along the first direction X.

[0178] The third pole piece 234 is adjacent to the second pole piece 232 of the adjacent structural unit 23, which means that the third pole piece 234 and the second pole piece 232 of the adjacent structural unit 23 are adjacent pole pieces, and this does not limit the presence of other components between them. The third pole piece 234 and the adjacent second pole piece 232 may be separated by an isolation membrane 233. The second pole piece 232 adjacent to the third pole piece 234 is the outermost second pole piece 232 in the structural unit 23 located at the end of the electrode assembly 2 along the first direction X.

[0179] In this embodiment, the outermost second pole piece 232 of the structural unit 23 located at the end of the electrode assembly 2 is fully utilized, so that the outermost second pole piece 232 and the third pole piece 234 of the structural unit 23 located at the end of the electrode assembly 2 can transmit metal ions during the charging and discharging process of the battery cell 10, which is beneficial to improving the capacity of the battery cell 10.

[0180] In some embodiments, referring to Figures 4-7 , the first electrode sheet 231 is a negative electrode sheet, and the second electrode sheet 232 is a positive electrode sheet. This makes it easier to achieve that the negative electrode sheet covers the positive electrode sheet, reducing the risk of the positive electrode sheet protruding from the negative electrode sheet, and improving the reliability of the electrode assembly 2. For example, in the case of a lithium-ion battery 100 as the battery cell 10, the negative electrode sheet covering the positive electrode sheet can reduce the risk of lithium plating, thereby improving the reliability of the electrode assembly 2.

[0181] In some embodiments, please refer to Figures 8 and 9. Figure 8 is an isometric view of the electrode assembly 2 provided in some embodiments of the present application; Figure 9 is an isometric view of the structural unit 23 shown in Figure 8. Each straight segment 2311 is provided with a first electrode tab 2313, and the multiple first electrode tabs 2313 in each structural unit 23 are aligned along the first direction X; and / or each second electrode piece 232 is provided with a second electrode tab 2321, and each structural unit 23 includes multiple second electrode pieces 232, and the multiple second electrode tabs 2321 in each structural unit 23 are aligned along the first direction X.

[0182] If the multiple first electrode tabs 2313 in each structural unit 23 are aligned along the first direction X, the first electrode tabs 2313 in two adjacent structural units 23 may also be aligned along the first direction X, and the first electrode tabs 2313 in the multiple structural units 23 may be connected together to form a first electrode tab portion. If the multiple second electrode tabs 2321 in each structural unit 23 are aligned along the first direction X, the second electrode tabs 2321 in two adjacent structural units 23 may also be aligned along the first direction X, and the second electrode tabs 2321 in the multiple structural units 23 may be connected together to form a second electrode tab portion. One of the first electrode tab portion and the second electrode tab portion forms the positive electrode tab 21 of the electrode assembly 2, and the other forms the negative electrode tab 22 of the electrode assembly 2.

[0183] If the multiple first pole tabs 2313 in the structural unit 23 are aligned along the first direction X, it is convenient for the bus connection. When cutting the first pole tabs 2313, the structural unit 23 can be cut as a whole, thereby improving the cutting efficiency of the first pole tabs 2313 and improving the production efficiency; if the multiple second pole tabs 2321 in the structural unit 23 are aligned along the first direction X, it is convenient for the bus connection. When cutting the second pole tabs 2321, the structural unit 23 can be cut as a whole, thereby improving the cutting efficiency of the second pole tabs 2321 and improving the production efficiency.

[0184] In some embodiments, please continue to refer to Figures 9 and 10. Figure 10 is a schematic diagram of the structure of the expanded structural unit 23 shown in Figure 9. The structural unit 23 also includes an isolation membrane 233. The first pole piece 231 and the second pole piece 232 are both composited with the isolation membrane 233. The isolation membrane 233 is configured to separate the first pole piece 231 and the second pole piece 232.

[0185] Isolation films 233 may be provided on both sides of the first electrode piece 231 to isolate the first electrode piece 231 from the second electrode pieces 232 on either side. The isolation films 233 are laminated with the first electrode piece 231, securing the isolation films 233 to the first electrode piece 231. The second electrode piece 232 is laminated with the isolation films 233, securing the second electrode piece 232 to the isolation films 233. The first electrode piece 231 and the second electrode piece 232 may be laminated with the isolation films 233 in various ways, such as by bonding or heat-seal-connecting the first electrode piece 231 and the second electrode piece 232 to the isolation films 233.

[0186] When forming the structural unit 23, the isolation membrane 233 can be compounded on both sides of the first pole piece 231, and then the second pole piece 232 can be alternately compounded on the isolation membrane 233 on both sides of the first pole piece 231, and then the first pole piece 231 is folded back and forth, and finally the straight section 2311 of the first pole piece 231 and the second pole piece 232 are alternately arranged, so that the structural unit 23 can be formed efficiently and quickly.

[0187] The isolation film 233 provides insulation isolation between the first electrode piece 231 and the second electrode piece 232, reducing the risk of short circuits within the electrode assembly 2. The first electrode piece 231 and the second electrode piece 232 are both composited with the isolation film 233, so that the first electrode piece 231, the second electrode piece 232, and the isolation film 233 in the structural unit 23 have good integrity, and the risk of misalignment between the first electrode piece 231 and the second electrode piece 232 is less likely to occur.

[0188] In some embodiments, please refer to Figure 11, which is an isometric view of the first pole piece 231 provided in some embodiments of the present application. The bending section 2312 is provided with a guide portion 23121, and the guide portion 23121 is configured to guide the bending section 2312 to bend.

[0189] The guide portion 23121 is a structure that guides the bending section 2312 to bend, so that the first pole piece 231 bends at a predetermined position, thereby forming the bending section 2312. The guide portion 23121 can be a groove, hole, or other structure provided in the bending section 2312, as long as it can guide the first pole piece 231 to bend at the predetermined position during the folding process to form the bending section 2312. The guide portion 23121 can be located in the middle of the bending section 2312 along the bending direction W of the bending section 2312.

[0190] The guide portion 23121 enables the first electrode piece 231 to be bent at a specified position, thereby improving the folding efficiency of the first electrode piece 231, increasing the consistency of the folding position, making the relative position of the straight section 2311 and the second electrode piece 232 more accurate, and ensuring the reliability of the electrode assembly 2.

[0191] In some embodiments, please continue to refer to FIG. 11 , the guide portion 23121 includes a groove 23122 disposed in the bending section 2312 .

[0192] The guide portion 23121 may include one or more grooves 23122. If there is one groove 23122 in the guide portion 23121, the groove 23122 may extend along the width direction Z of the first pole piece. If there are multiple grooves 23122 in the guide portion 23121, the multiple grooves 23122 may be spaced apart along the width direction Z of the first pole piece. The width direction Z, the first direction X, and the second direction Y of the first pole piece are perpendicular to each other.

[0193] In this embodiment, the bent section 2312 is weaker in the area where the groove 23122 is provided. The groove 23122 provides a good guiding effect, making it easier for the first pole piece 231 to bend at the location of the groove 23122 to form the corresponding bent section 2312. This guiding portion 23121 has a simple structure and is easy to form. Furthermore, the provision of the groove 23122 can alleviate the problem of lithium deposition at the bend of the first pole piece 231, thereby increasing the service life of the electrode assembly 2.

[0194] In some embodiments, please refer to Figures 12-16. Figure 12 is a schematic structural diagram of a first electrode sheet 231 provided in some embodiments of the present application; Figure 13 is a partial view of the first electrode sheet 231 shown in Figure 12 after unfolding; Figure 14 is a top view of the first electrode sheet 231 shown in Figure 13; Figure 15 is a schematic structural diagram of the first electrode sheet 231 provided in still other embodiments of the present application; and Figure 16 is a partial view of the first electrode sheet 231 shown in Figure 15 after unfolding. The bent section 2312 includes a current collector 23123 and two active material layers 23124. The two active material layers 23124 are respectively disposed on either side of the current collector 23123, and at least one of the active material layers 23124 is provided with a groove 23122.

[0195] One active material layer 23124 may be provided with grooves 23122 , or both active material layers 23124 may be provided with grooves 23122 . The depth of the grooves 23122 may be less than the thickness of the active material layer 23124 , or may be equal to the thickness of the active material layer 23124 .

[0196] In this embodiment, by providing a groove 23122 in at least one active material layer 23124 of the bent section 2312 , the bent section 2312 is partially thinned and weakened, and the implementation is simple.

[0197] In some embodiments, referring to FIG. 12 to FIG. 14 , an active material layer 23124 is provided with a groove 23122 .

[0198] In the bent section 2312, the groove 23122 can be provided in an active material layer 23124 located inside the current collector 23123, or in an active material layer 23124 located outside the current collector 23123. For example, in the case where the bent section 2312 is arc-shaped, the radius of the active material layer 23124 located outside the current collector 23123 is greater than the radius of the active material layer 23124 located inside the current collector 23123. As an example, in the embodiment shown in Figures 12-14, the groove 23122 extends along the width direction Z of the first electrode sheet and penetrates the active material layer 23124.

[0199] In this embodiment, only one layer of active material layer 23124 is provided with grooves 23122, which can reduce the difficulty of forming the first pole piece 231. Specifically, when only one layer of active material layer 23124 is provided with grooves 23122, and the first pole piece 231 has more than two bends, some grooves 23122 are located on the inner side of the bend section 2312, and some grooves 23122 are located on the outer side of the bend section 2312. This can effectively control the lithium deposition problem of the first pole piece 231 while reducing the difficulty of forming. Moreover, when only one layer of active material layer 23124 is provided with grooves 23122, when the first pole piece 231 is unfolded, all grooves 23122 are located on the same side of the first pole piece 231. Compared with the need to position and align the grooves 23122 on both sides, the process of grooving on one side is less difficult and more convenient to operate.

[0200] In some embodiments, referring to FIG. 15 and FIG. 16 , both active material layers 23124 are provided with grooves 23122 .

[0201] The grooves 23122 on the two active material layers 23124 are correspondingly arranged. For example, the bend section 2312 is arc-shaped, and the grooves 23122 on the two active material layers 23124 are located in the same radial direction of the bend section 2312. Along the radial direction of the bend section 2312, the grooves 23122 on the two active material layers 23124 are located on either side of the current collector 23123. The grooves 23122 extend along the width direction Z of the first electrode sheet and penetrate the active material layers 23124.

[0202] In an embodiment where the depth of the groove 23122 is equal to the thickness of the active material layer 23124, since grooves 23122 are provided in both active material layers 23124, the current collector 23123 is not covered by the active material layer 23124 in the area where the grooves 23122 are provided, and this area is in an exposed state. This area is the inactive material layer area 23125 of the current collector 23123.

[0203] In this embodiment, the active material layers 23124 on both sides of the current collector 23123 are provided with grooves 23122, making the bent section 2312 weaker in the area where the grooves 23122 are provided, making it easier to bend. This also effectively improves the lithium deposition problem of the first electrode 231.

[0204] In some embodiments, referring to FIG. 17 , FIG. 17 is a partial view of an unfolded first electrode sheet 231 provided in yet other embodiments of the present application. The guide portion 23121 further includes a through hole 23126 extending through the current collector 23123 . The region of the current collector 23123 corresponding to the groove 23122 forms an inactive material layer region 23125 , and the through hole 23126 is disposed in the inactive material layer region 23125 .

[0205] In this embodiment, the depth of the groove 23122 is equal to the thickness of the active material layer 23124 , so that the current collector 23123 is not covered by the active material layer 23124 in the area where the groove 23122 is provided, thereby forming an inactive material layer area 23125 .

[0206] The inactive material layer region 23125 may include one or more through-holes 23126. The through-holes 23126 may have various shapes, such as circular or rectangular. The through-holes 23126 may be positioned centrally within the width of the inactive material layer 23124. The width of the inactive material layer 23124 is perpendicular to the width direction Z of the first electrode sheet and the thickness direction of the current collector 23123.

[0207] In this embodiment, the provision of through-holes 23126 reduces the stiffness of the inactive material layer region 23125 of the current collector 23123. This reduces the stiffness of the inactive material layer region 23125, thereby enhancing the folding effect and further improving the folding efficiency of the first pole piece 231. Furthermore, within the battery cell 10, the electrolyte can flow through the through-holes 23126 between the first pole piece 231 and the second pole piece 232, facilitating electrolyte wetting of the pole pieces. Furthermore, this effectively alleviates lithium deposition issues within the first pole piece 231.

[0208] In some embodiments, please refer to Figure 18, which is a top view of the first electrode plate 231 shown in Figure 17. The inactive material layer region 23125 is provided with a plurality of through holes 23126, which are spaced apart along the width direction Z of the first electrode plate.

[0209] The number of through holes 23126 on the inactive material layer region 23125 may be two, three, four, five or more.

[0210] In this embodiment, the inactive material layer region 23125 is provided with a plurality of through holes 23126 arranged along the width direction Z of the first electrode piece, further reducing the stiffness of the current collector 23123 in the inactive material layer region 23125 , making it easier for the first electrode piece 231 to bend in the inactive material layer region 23125 .

[0211] In some embodiments, referring again to FIG. 14 and FIG. 18 , the groove 23122 extends along the width direction Z of the first electrode sheet and penetrates the active material layer 23124 .

[0212] It can be understood that, along the width direction Z of the first electrode sheet, both ends of the groove 23122 extend to both ends of the active material layer 23124 respectively.

[0213] It should be noted that, whether the groove 23122 is provided only on the active material layer 23124 on one side of the current collector 23123 or on both sides of the current collector 23123 , the groove 23122 can extend along the first direction X and penetrate the active material layer 23124 .

[0214] In this embodiment, the groove 23122 is easier to form, and the first pole piece 231 is easier to bend in the area of ​​the groove 23122 .

[0215] In some embodiments, referring to Figures 19 and 20, Figure 19 is a top view of the unfolded first electrode sheet 231 provided in some embodiments of the present application; Figure 20 is a top view of the unfolded first electrode sheet 231 provided in still other embodiments of the present application. The active material layer 23124 is provided with a plurality of grooves 23122, which are spaced apart along the width direction Z of the first electrode sheet.

[0216] The active material layer 23124 may be provided with two, three, four, five, or more grooves 23122. It is understood that in embodiments where only one active material layer 23124 located on one side of the current collector 23123 is provided with grooves 23122, the active material layer 23124 is provided with multiple grooves 23122; and in embodiments where both active material layers 23124 located on either side of the current collector 23123 are provided with grooves 23122, each active material layer 23124 is provided with multiple grooves 23122.

[0217] In the embodiment shown in FIG19 , the region of the current collector 23123 corresponding to the groove 23122 forms an inactive material layer region 23125 (not shown in FIG19 ), and the inactive material layer region 23125 is not provided with a through-hole 23126. In the embodiment shown in FIG20 , the region of the current collector 23123 corresponding to the groove 23122 forms an inactive material layer region 23125 (not shown in FIG20 ), and the inactive material layer region 23125 is provided with a through-hole 23126.

[0218] In this embodiment, the active material layer 23124 is provided with a plurality of grooves 23122 spaced apart along the width direction Z of the first pole piece. The first pole piece 231 has good bending performance in the region of the plurality of grooves 23122, and the first pole piece 231 has sufficient strength in this region and is not prone to the risk of breakage.

[0219] In some embodiments, please refer to Figures 21 to 24. Figure 21 is a partial view of the unfolded first electrode sheet 231 provided in other embodiments of the present application; Figure 22 is a top view of the first electrode sheet 231 shown in Figure 21; Figure 23 is a partial view of the unfolded first electrode sheet 231 provided in still other embodiments of the present application; and Figure 24 is a top view of the current collector 23123 shown in Figure 23. The bent section 2312 includes a current collector 23123 and two active material layers 23124. The two active material layers 23124 are respectively disposed on either side of the current collector 23123. The guide portion 23121 includes a through hole 23126 disposed in the bent section 2312. The through hole 23126 penetrates the current collector 23123 and the two active material layers 23124; alternatively, the through hole 23126 penetrates the current collector 23123, and the two active material layers 23124 cover the through hole 23126.

[0220] There may be one or more through holes 23126 disposed in the bent section 2312. The through holes 23126 may be in various shapes, such as circular, rectangular, etc.

[0221] In the embodiment shown in Figures 21 and 22 , the through hole 23126 passes through the current collector 23123 and the two active material layers 23124. In the embodiment shown in Figures 23 and 24 , the through hole 23126 is provided in the current collector 23123, and the through hole 23126 passes through the current collector 23123, and the two active material layers 23124 both cover the through hole 23126.

[0222] In this embodiment, the stiffness of the region where the through hole 23126 is provided in the bending section 2312 is reduced, making it easier for the first pole piece 231 to bend at the position of the through hole 23126 to form the corresponding bending section 2312. If the through hole 23126 passes through the current collector 23123 and the two layers of active material layers 23124, the bending performance of the first pole piece 231 in the region where the through hole 23126 is provided is better. In addition, in the battery cell 10, the electrolyte can flow between the first pole piece 231 and the second pole piece 232 through the through hole 23126, which is conducive to the electrolyte infiltration of the pole pieces. If the through hole 23126 passes through the current collector 23123 and the two layers of active material layers 23124 cover the through hole 23126, the first pole piece 231 has sufficient strength in the region where the through hole 23126 is provided, and is less likely to break during the bending process of the first pole piece 231. In addition, when forming the first pole piece 231 , a through hole 23126 can be processed on the current collector 23123 first, and then an active material layer 23124 is set on the surface of the current collector 23123 so that the active material layer 23124 covers the through hole 23126 , thereby reducing the difficulty of forming the first pole piece 231 .

[0223] In some embodiments, referring to Figures 22 and 24 , the guide portion 23121 includes a plurality of through holes 23126 , and the plurality of through holes 23126 are spaced apart along the width direction Z of the first pole piece.

[0224] The number of through holes 23126 on the bending section 2312 can be two, three, four, five or more.

[0225] In this embodiment, the bending section 2312 is provided with a plurality of through holes 23126 arranged along the width direction Z of the first pole piece, further reducing the stiffness of the area where the through holes 23126 are set in the bending section 2312, making it easier for the first pole piece 231 to bend in the area where the through holes 23126 are set.

[0226] In some embodiments, the through hole 23126 is a rectangular hole.

[0227] The cross section of the through hole 23126 is rectangular, and the cross section of the through hole 23126 is perpendicular to the axial direction of the through hole 23126 . The axial direction of the through hole 23126 is consistent with the thickness direction of the bent section 2312 .

[0228] In this embodiment, the through hole 23126 is a rectangular hole. This type of through hole 23126 has a simple structure and is easy to form.

[0229] In some embodiments, referring to FIG. 18 , FIG. 20 , FIG. 22 and FIG. 24 , the cross-section of the through hole 23126 is a rectangle, and the length direction of the rectangle is consistent with the width direction Z of the first pole piece.

[0230] The length direction of the rectangle is the length direction of the through hole 23126. In the rectangle, the long side is greater than the short side.

[0231] In this embodiment, the length direction of the through hole 23126 is consistent with the width direction Z of the first pole piece, so that the folding position of the first pole piece 231 is more accurate.

[0232] In some embodiments, referring to Figures 25 and 26, Figure 25 is a partial enlarged view of point A in Figure 18; Figure 26 is a partial enlarged view of point B in Figure 22. The length of the rectangle is a, the width is b, and the following conditions are met: 10≤a / b≤400.

[0233] a / b can be any one of the point values ​​of 10, 20, 40, 80, 100, 150, 180, 200, 250, 280, 300, 350, 380, 400 or any range between them.

[0234] When a / b is less than 10, the through hole 23126 is larger in the bending direction W of the bending section 2312, and the folding consistency of the first pole piece 231 in the through hole 23126 region is poor, affecting the folding accuracy of the first pole piece 231. When a / b is greater than 400, the through hole 23126 is smaller in the bending direction W of the bending section 2312, and the through hole 23126 has a weaker ability to guide the bending of the first pole piece 231, which also affects the folding accuracy of the first pole piece 231. Therefore, when 10≤a / b≤400, the through hole 23126 is a slender structure extending along the width direction Z of the first pole piece, which improves the consistency of the folding position of the first pole piece 231, making the folding position of the first pole piece 231 more accurate and improving the folding efficiency of the first pole piece 231.

[0235] In some embodiments, 20≤a / b≤100.

[0236] a / b can be any point value among 20, 30, 40, 50, 60, 70, 80, 90, 100 or any range between them.

[0237] In this embodiment, 20≤a / b≤100, which can further improve the folding efficiency of the first pole piece 231 .

[0238] In some embodiments, 3 mm ≤ a ≤ 20 mm; and / or, 0.05 mm ≤ b ≤ 0.3 mm.

[0239] a can be any point value of 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, or a range value between any two of them.

[0240] b can be any one of the point values ​​of 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, and 0.3mm, or a range value between any two of them.

[0241] An embodiment of the present application provides a battery cell 10 , comprising a housing 1 and an electrode assembly 2 provided in any one of the above embodiments, wherein the electrode assembly 2 is accommodated in the housing 1 .

[0242] An embodiment of the present application provides a battery 100 , comprising the battery cell 10 provided in any one of the above embodiments.

[0243] An embodiment of the present application provides an electrical device, comprising a battery cell 10 provided by any one of the above embodiments, wherein the battery cell 10 is used to provide electrical energy.

[0244] The present embodiment also provides an electrode assembly 2, comprising a plurality of structural units 23 stacked along a first direction X. The structural units 23 include a first electrode sheet 231, a second electrode sheet 232, and a separator 233. Separator 233 is laminated on both sides of the first electrode sheet 231, and the second electrode sheet 232 is laminated on the separator 233. The separator 233 is configured to separate the first electrode sheet 231 from the second electrode sheet 232. The first electrode sheet 231 has a folded structure and includes a bent section 2312 and a plurality of straight sections 2311. Adjacent straight sections 2311 are spaced apart along the first direction X and connected by a bent section 2312. The first electrode sheet 231 is a negative electrode sheet, and the second electrode sheet 232 is a positive electrode sheet. The second electrode sheet 232 and the straight sections 2311 are alternately arranged along the first direction X. In the structural unit 23 , the number of the straight sections 2311 of the first pole piece 231 is equal to the number of the second pole pieces 232 .

[0245] The number of straight sections 2311 of the first pole piece 231 in at least one structural unit 23 is an odd number, and the number of straight sections 2311 of the first pole pieces 231 in at least two structural units 23 are unequal.

[0246] The bending section 2312 is provided with a groove 23122, which is configured to guide the bending section 2312. The bending section 2312 includes a current collector 23123 and two active material layers 23124. The two active material layers 23124 are respectively arranged on either side of the current collector 23123. Both active material layers 23124 are provided with a groove 23122. The area corresponding to the current collector 23123 and the groove 23122 forms an inactive material layer region 23125. The inactive material layer region 23125 is provided with a plurality of through holes 23126. The plurality of through holes 23126 are spaced apart along the width direction Z of the first electrode sheet. The cross-section of the through holes 23126 is rectangular, and the length direction of the rectangle is consistent with the width direction Z of the first electrode sheet. The length of the rectangle is a, and the width is b, satisfying: 10≤a / b≤400, 3mm≤a≤20mm, 0.05mm≤b≤0.3mm.

[0247] In the above solution, the electrode assembly 2 is divided into multiple structural units 23, which reduces the number of layers of straight sections 2311 of the first electrode pieces 231 in the structural units 23, thereby reducing the risk of the structural units 23 deflecting. This can reduce the risk of deflection after multiple structural units 23 are stacked, thereby reducing the risk of misalignment between the electrode pieces, and effectively improving the reliability of the electrode assembly 2. The number of straight sections 2311 of the first electrode piece 231 in at least one structural unit 23 is an odd number, so that the number of bent sections 2312 on both sides of the structural unit 23 in the second direction Y is equal. When the first electrode piece 231 is subjected to a force along the first direction X, the bent sections 2312 on both sides of the structural unit 23 can deform, improving the structural stability of the first electrode piece 231, and making the structural unit 23 less prone to deflection. This reduces the risk of misalignment between the electrode pieces and improves the reliability of the electrode assembly 2. The number of straight sections 2311 of the first electrode sheet 231 in at least two structural units 23 is different, resulting in a variety of structural units 23 types in the electrode assembly 2. Multiple structural units 23 can be combined in a variety of ways, improving the variability of the electrode assembly 2 and adapting to market demand to a greater extent. In addition, both active material layers 23124 of the bending section 2312 are provided with grooves 23122, making it easier for the first electrode sheet 231 to bend at the location of the grooves 23122, thereby guiding the bending of the first electrode sheet 231, improving the folding efficiency of the first electrode sheet 231, and achieving higher consistency in the folding position. Because the inactive material layer region 23125 of the current collector 23123 is provided with multiple through holes 23126 at intervals, the stiffness of the current collector 23123 in the inactive material layer region 23125 can be effectively reduced, making it easier for the first electrode sheet 231 to bend in the inactive material layer region 23125 and effectively improving the lithium deposition problem of the first electrode sheet 231. In addition, since the cross-section of the through hole 23126 is a rectangle, the length direction of the rectangle is consistent with the width direction Z of the first pole piece, and the length a and width b of the rectangle satisfy: 10≤a / b≤400, the through hole 23126 is a slender structure extending along the width direction Z of the first pole piece, which improves the consistency of the folding position of the first pole piece 231, makes the folding position of the first pole piece 231 more accurate, and improves the folding efficiency of the first pole piece 231.

[0248] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0249] The above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit this application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application are intended to be within the scope of protection of this application.

Claims

1. An electrode assembly, comprising a plurality of structural units, wherein the plurality of structural units are stacked along a first direction, and the structural units include: A first pole piece, comprising a bent section and a plurality of straight sections, wherein two adjacent straight sections are spaced apart along a first direction and connected to one of the bent sections; The second pole piece has a polarity opposite to that of the first pole piece, and along the first direction, the second pole piece and the straight section are alternately arranged.

2. The electrode assembly according to claim 1, wherein: The number of the straight sections of the first pole piece in at least one of the structural units is greater than two.

3. The electrode assembly according to claim 1 or 2, wherein: The number of the straight sections of the first pole piece in at least one of the structural units is an odd number.

4. The electrode assembly according to any one of claims 1 to 3, wherein: The number of the straight sections of the first pole piece in each of the structural units is greater than two.

5. The electrode assembly according to any one of claims 1 to 4, wherein: The number of the straight sections of the first pole piece in each of the structural units is an odd number.

6. The electrode assembly according to claim 4 or 5, wherein: The number of the straight sections of the first pole piece in each of the structural units is three.

7. The electrode assembly according to any one of claims 1 to 3, wherein: The number of straight sections of the first pole pieces in at least two of the structural units is different.

8. The electrode assembly according to any one of claims 1 to 3 and 7, wherein: The plurality of structural units include a first structural unit, a second structural unit and a third structural unit arranged in sequence along the first direction; The number of straight segments of the first pole piece in the first structural unit and the number of straight segments of the first pole piece in the third structural unit are both even numbers, and the number of straight segments of the first pole piece in the second structural unit is an odd number.

9. The electrode assembly according to any one of claims 1 to 8, wherein: Along the first direction, the two straight sections of the first pole piece at two ends are respectively a first straight section and a second straight section; In two adjacent structural units, the first straight segment of one structural unit and the second straight segment of the other structural unit are two adjacent straight segments, and along the second direction, one end of the first straight segment of one structural unit away from the bending segment and one end of the second straight segment of the other structural unit away from the bending segment are respectively located on both sides of the electrode assembly, and the second direction is perpendicular to the first direction.

10. The electrode assembly according to any one of claims 1 to 9, wherein: In the structural unit, the number of the straight sections of the first pole piece is equal to the number of the second pole piece.

11. The electrode assembly according to any one of claims 1 to 10, wherein: The electrode assembly further includes a third pole piece, the third pole piece having the same polarity as the first pole piece; Along the first direction, at least one side of the plurality of structural units is provided with the third pole piece, and the third pole piece is adjacent to the second pole piece of the adjacent structural unit.

12. The electrode assembly according to any one of claims 1 to 11, wherein: The first pole piece is a negative pole piece, and the second pole piece is a positive pole piece.

13. The electrode assembly according to any one of claims 1 to 12, wherein: Each of the straight sections is provided with a first pole lug, and a plurality of the first pole lugs in each of the structural units are aligned along the first direction; and / or Each of the second pole pieces is provided with a second pole lug, each of the structural units includes a plurality of the second pole pieces, and the plurality of the second pole lugs in each of the structural units are aligned along the first direction.

14. The electrode assembly according to any one of claims 1 to 13, wherein: The structural unit further includes an isolation membrane, the first pole piece and the second pole piece are both compounded on the isolation membrane, and the isolation membrane is configured to separate the first pole piece and the second pole piece.

15. The electrode assembly according to any one of claims 1 to 14, wherein: The bending section is provided with a guide portion, and the guide portion is configured to guide the bending section to bend.

16. The electrode assembly according to claim 15, wherein: The guide portion includes a groove arranged on the bending section.

17. The electrode assembly according to claim 16, wherein: The bending section includes a current collector and two active material layers, the two active material layers are respectively arranged on both sides of the current collector, and at least one active material layer is provided with the groove.

18. The electrode assembly according to claim 17, wherein: One of the active material layers is provided with the groove.

19. The electrode assembly according to claim 17, wherein: The two active material layers are both provided with the grooves.

20. The electrode assembly according to claim 19, wherein: The guide portion further includes a through hole penetrating the current collector, a region of the current collector corresponding to the groove forms an inactive material layer region, and the through hole is disposed in the inactive material layer region.

21. The electrode assembly according to claim 20, wherein: The inactive material layer is provided with a plurality of through holes, and the plurality of through holes are arranged at intervals along the width direction of the first pole piece.

22. The electrode assembly according to any one of claims 17 to 21, wherein: The groove extends along the width direction of the first pole piece and penetrates the active material layer.

23. The electrode assembly according to any one of claims 17 to 21, wherein: The active material layer is provided with a plurality of the grooves, and the plurality of the grooves are arranged at intervals along the width direction of the first pole piece.

24. The electrode assembly according to claim 15, wherein: The bending section includes a current collector and two active material layers, the two active material layers are respectively arranged on both sides of the current collector, and the guide portion includes a through hole arranged in the bending section; The through hole penetrates the current collector and the two active material layers; or The through hole penetrates the current collector, and the two active material layers cover the through hole.

25. The electrode assembly of claim 24, wherein: The guide portion includes a plurality of through holes, and the plurality of through holes are arranged at intervals along a width direction of the first pole piece.

26. The electrode assembly of claim 20, 21, 24 or 25, wherein: The through hole is a rectangular hole.

27. The electrode assembly of claim 26, wherein: The cross section of the through hole is a rectangle, and the length direction of the rectangle is consistent with the width direction of the first pole piece.

28. The electrode assembly of claim 27, wherein: The length of the rectangle is a, and the width is b, satisfying: 10≤a / b≤400.

29. The electrode assembly of claim 28, wherein: 20≤a / b≤100.

30. The electrode assembly according to claim 28 or 29, wherein: 3mm≤a≤20mm; and / or, 0.05mm≤b≤0.3mm.

31. A battery cell, comprising: shell; The electrode assembly according to any one of claims 1-30, wherein the electrode assembly is accommodated in the housing.

32. A battery comprising the battery cell according to claim 31.

33. An electrical device comprising the battery cell according to claim 31, wherein the battery cell is used to provide electrical energy.

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