CN113922000A - Winding type battery cell and electrochemical device - Google Patents
Winding type battery cell and electrochemical device Download PDFInfo
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- CN113922000A CN113922000A CN202111167851.1A CN202111167851A CN113922000A CN 113922000 A CN113922000 A CN 113922000A CN 202111167851 A CN202111167851 A CN 202111167851A CN 113922000 A CN113922000 A CN 113922000A
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- current collector
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Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/531—Electrode connections inside a battery casing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Composite Materials (AREA)
- Secondary Cells (AREA)
- Connection Of Batteries Or Terminals (AREA)
Abstract
The invention provides a winding type battery cell and an electrochemical device, wherein the electrochemical device comprises a positive plate and a negative plate, and at least one of the positive plate and the negative plate has the following electrode structure: the electrode structure comprises a current collector and an active substance layer positioned on at least one surface of the current collector, wherein the current collector comprises two metal layers and a polymer layer positioned between the two metal layers; the electrode structure is provided with at least three straight parts and a bending part connected between every two straight parts, and the electrode structure is bent through the bending part to form a coiled structure; the electrode structure is equipped with two at least first utmost point ears, first utmost point ear sets up the mass flow body is equipped with the surface on active substance layer and distributes on the straight portion. The invention can improve the performances of the electrochemical device such as energy density, multiplying power and the like.
Description
Technical Field
The invention belongs to the field of batteries, and particularly relates to a winding type battery cell and an electrochemical device.
Background
At present, electrochemical devices represented by lithium ion batteries are widely applied to consumer electronics, electric vehicles, energy storage and the like, and among them, lithium ion batteries are becoming a research hotspot at the present stage. In order to optimize the energy density, safety and other performances of the battery, a plated current collector formed by compounding a metal foil and a polymer film (or polymer layer) is gradually developed, and in the plated current collector, a polymer layer formed by a lighter polymer material is used for replacing part of the metal foil, so that the energy density of the battery can be improved. Therefore, optimizing the electrode structure, improving the safety of the electrochemical device, reducing the sheet resistance, and improving the performance such as the multiplying power of the electrochemical device are still important issues to be faced by those skilled in the art.
Disclosure of Invention
The invention provides a winding type battery core and an electrochemical device, which can improve the safety of a battery, simultaneously reduce the sheet resistance, improve the multiplying power performance and other performances of the battery, effectively overcome the defects in the prior art,
in one aspect of the present invention, a winding type battery cell is provided, which includes a positive plate and a negative plate, and at least one of the positive plate and the negative plate has the following electrode structure: the electrode structure comprises a current collector and an active substance layer positioned on at least one surface of the current collector, wherein the current collector comprises two metal layers and a polymer layer positioned between the two metal layers; the electrode structure is provided with at least three straight parts and a bending part connected between every two straight parts, and the electrode structure is bent through the bending part to form a coiled structure; the electrode structure is equipped with two at least first utmost point ears, first utmost point ear sets up the mass flow body is equipped with the surface on active substance layer and distributes on the straight portion.
According to an embodiment of the invention, the solar collector further comprises an external tab, one side of the first tab extends out of the outer edge of the current collector and is welded with the external tab, and the other side of the first tab is surrounded by the active material layer.
According to an embodiment of the present invention, in a direction perpendicular to the surface of the current collector of the straight portion, a straight portion provided with a first tab is present on each of a first side and a second side of the external tab, and the first side is opposite to the second side.
According to an embodiment of the present invention, the first tabs are distributed on at least two straight portions, n straight portions without the first tabs are provided between every two straight portions with the first tabs in a winding direction of the electrode structure, and n is an odd number.
According to an embodiment of the present invention, projections of each two of the at least two first tabs on a first plane, which is a plane parallel to the current collector surface of the straight portion in the winding structure, are at least partially overlapped.
According to an embodiment of the invention, n comprises at least one of 1, 3, 5.
According to an embodiment of the invention, said at least partial overlap satisfies: k is w1/w2, k is equal to or greater than 80%, k represents the degree of overlap, w1 is the width of the overlap of the projections of the two first tabs on the first plane in the first direction, w2 is the width of the first tab in the first direction, and the first direction is the direction from the bent portion at one end of the straight portion to the bent portion at the other end of the straight portion.
According to an embodiment of the present invention, both surfaces of the current collector are provided with the active material layer; the two surfaces of the current collector of the electrode structure are distributed with the first lugs.
According to an embodiment of the present invention, a ratio of the number of straight portions of the electrode structure to the number of first tabs is 3 to 10: 1.
according to an embodiment of the present invention, the number of straight portions of the electrode structure is 8 to 30.
According to an embodiment of the invention, the metal layer comprises at least one of aluminium, copper, nickel, silver, gold, iron.
According to an embodiment of the invention, the polymer layer comprises at least one of polyethylene terephthalate, polypropylene, polyethylene, polyimide, polyetherketone, polyphenylene sulfide.
According to an embodiment of the present invention, a transition layer is present or absent between the metal layer and the polymer layer, and the transition layer comprises at least one of aluminum oxide, magnesium oxide, and titanium oxide.
In another aspect of the present invention, an electrochemical device is provided, which includes the above-mentioned winding type battery cell.
According to the invention, the current collector compounded by the metal layer and the polymer layer is adopted, the polymer layer is the substrate layer, the metal layers on the front surface and the back surface of the polymer layer are the conductive layers, the safety and the mass energy density of the electrode structure can be improved through the conductive layer-substrate layer-conductive layer sandwich structure, and meanwhile, at least two first lugs are distributed on the straight part of the electrode structure, so that the sheet resistance can be reduced, the internal resistance of the electrochemical device is further reduced, and the performances of the electrochemical device such as the multiplying power and the like are improved. Therefore, the invention can improve the safety, the rate capability and other performances of the battery at the same time, and has important significance for practical industrial application.
Drawings
FIG. 1 is a schematic diagram of a first surface of an electrode structure showing a void foil area prior to forming a rolled structure in one embodiment of the present invention;
FIG. 2 is a schematic diagram of a second surface of an electrode structure showing a void foil area prior to forming a rolled structure in one embodiment of the present invention;
fig. 3 is a schematic view of a first surface of an electrode structure showing a first tab in an embodiment of the invention;
fig. 4 is a schematic structural diagram of a winding type battery cell according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of the region enclosed by the dotted line x in FIG. 4;
fig. 6 is a schematic diagram illustrating a cell structure of an overlapping portion of a first tab of an electrode structure according to an embodiment of the present invention;
FIG. 7 is a schematic structural view of a first electrode tab of comparative example 2;
fig. 8 is a schematic diagram of a cell structure of comparative example 3.
Description of reference numerals: 1. a first current collector; 1', a second current collector; 2. a first active material layer; 2', a second active material layer; 3. a straight portion; 4. a bending section; 5. a first tab; 5', a second tab; 6. a region of empty foil; 7. an overlapping portion; 8. externally connecting a tab; 9. welding the part; 10. gluing a tab; 11. a first electrode pad; 12. a second electrode pad; 13. a diaphragm; 31. 31': a first straight portion; 33: a third straight portion; 34': and a fourth straight portion.
Detailed Description
The present invention is described in further detail below in order to enable those skilled in the art to better understand the aspects of the present invention. The following detailed description is merely illustrative of the principles and features of the present invention, and the examples are intended to be illustrative of the invention and not limiting of the scope of the invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort belong to the protection scope of the present invention. In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only, for example, to distinguish components for clarity and to explain/explain technical solutions, and are not to be interpreted as indicating or implying any number of indicated technical features or an order of substantial significance.
The winding type battery cell comprises a positive plate and a negative plate, wherein at least one of the positive plate and the negative plate has the following electrode structure: the electrode structure comprises a current collector (such as a first current collector 1 in fig. 4) and an active material layer (such as a first active material layer 2 in fig. 4) on at least one surface of the current collector, wherein the current collector comprises two metal layers and a polymer layer between the two metal layers; the electrode structure is provided with at least three straight parts (such as straight parts 3 in figures 1 to 4) and a bending part (such as bending part 4 in figures 1 to 4) connected between every two straight parts, and the electrode structure is bent by the bending part to form a coiled structure; the electrode structure has at least two first tabs (e.g., first tabs 5 in fig. 3 and 4) disposed on the surface of the current collector provided with the active material layer and distributed on the straight portion.
In general, in the above-mentioned winding structure, the straight portions are stacked, that is, the planes of the current collector surfaces of the straight portions are substantially parallel to each other (the current collector surface refers to the functional surface of the current collector on which the active material layer is disposed), the bent portions are bent, one end of each bent portion is connected to one straight portion, the other end of each bent portion is connected to another straight portion, the direction from the bent portion at one end of the winding structure to the bent portion at the other end of the winding structure (i.e., the direction from the bent portion connected to one end of a straight portion to the bent portion connected to the other end of the straight portion) is the length direction of the winding structure, the direction from one straight portion of the winding structure to the other straight portion of the winding structure is the width direction of the winding structure (i.e., the thickness direction of the straight portion, as shown in fig. 4), the length direction of the winding structure is also the length direction of each straight portion of the winding structure, the width direction of the winding structure is also the width direction of the winding cell.
In the present invention, the first tab is generally disposed in the middle (i.e. not at the end) of the electrode structure, one side of the first tab extends out of the outer edge of the current collector, and the other sides of the first tab are surrounded by the active material layer. In some embodiments, the wound electrical core further includes an external tab, one side of the first tab extends out of the outer edge of the current collector and is welded to the external tab, and the other sides of the first tab are surrounded by the active material layer.
Specifically, the surface of the current collector provided with the straight portion of the first tab has a void foil area (e.g., void foil area 6 in fig. 1 and 2) in which the first tab is disposed; in the projection parallel to the surface of the current collector, one side (marked as side a) of the empty foil area and one side (marked as side B) of the surface of the current collector provided with the empty foil area are on the same straight line, and the rest sides of the empty foil area are connected with the active material layer, as shown in fig. 1 and fig. 2, the shape of the empty foil area is rectangular or square, the side a of the empty foil area and the side B of the surface of the current collector are on the same straight line, and the rest three sides are all connected with the active material layer. The first tab is welded in the empty foil area, and one side of the first tab extends out of the outer edge of the current collector from the edge A of the empty foil area and is welded with the external tab (as shown in fig. 4). The side B is generally a long side of the current collector, the current collector is a composite current collector formed by sequentially laminating a metal layer, a polymer layer and a metal layer, an active substance layer is not arranged in a hollow foil area, the surface of the hollow foil area is the metal layer, a first tab is welded on the metal layer in the hollow foil area, the number of the hollow foil areas in the electrode structure is the same as that of the first tabs, and namely the first tab is arranged in the hollow foil area. In addition, the thickness of the first tab can be basically the same as that of the active material layer, so that the volume energy density of the battery cell can be further improved.
In some embodiments, the first tab includes a first connection portion and a second connection portion, the first tab is welded on the surface of the current collector (i.e. welded on the surface of the current collector in the empty foil region) through the first connection portion, one side of the first connection portion extends out of the outer edge of the current collector, the other sides are surrounded by the active material layer, one end of the second connection portion is connected to the first connection portion, and the other end of the second connection portion is welded to the external tab, so as to weld the first tab to the external tab, wherein the first connection portion, the second connection portion, and the external tab are all in a straight structure (i.e. are not bent substantially).
Generally, all the first tabs of the electrode structure are welded to the same external tab, one end of the external tab is welded to the first tab, and adhesive paper (or tab adhesive, as shown in fig. 5) is attached between one end of the external tab and the other end of the external tab, so as to facilitate the packaging of the battery cell and the assembly of the battery and other electrochemical devices. In some embodiments, in a direction perpendicular to the surface of the current collector of the straight portion, the straight portion provided with the first tab is present on both the first side and the second side of the external tab, and the first side is opposite to the second side, that is, the straight portion provided with the first tab is disposed on the first side and the second side of the external tab, and the external tab is located between at least two straight portions provided with the first tab, which is beneficial to saving a cell space and improving performances such as energy density of a cell.
Optionally, in a direction perpendicular to the surface of the straight portion of the current collector, a distance from one of the straight portions provided with the first tabs and distributed on the first side of the external tab, which is farthest from the external tab, to the external tab is substantially equal to a distance from one of the straight portions provided with the first tabs and distributed on the second side of the external tab, which is farthest from the external tab, to the external tab, that is, the external tab is arranged between all the straight portions provided with the first tabs. For example, if the number of straight portions without tabs between every two adjacent straight portions provided with the first tabs is the same, the difference between the number of straight portions provided with the first tabs on the first side of the external tab and the number of straight portions provided with the first tabs on the second side of the external tab may be controlled to be not greater than 1, and preferably 0.
In some embodiments, one side of the first tab extends out of the outer edge of the current collector and is welded with an external tab, the length of a welding part formed by the welding in the length direction of the external tab is 0.2-2 mm, and the length direction of the external tab is substantially parallel to the plane of the surface of the current collector in the straight part.
In some embodiments, the first tabs are distributed on at least two straight portions, and in the winding direction of the electrode structure (i.e. calculated according to the straight portion sequence of the winding direction), n straight portions without the first tabs are arranged between every two straight portions with the first tabs, where n is an odd number, which is not only beneficial to reducing the sheet resistance and optimizing the performance of the battery cell, but also beneficial to welding the first tabs with external tabs, saving the space of the battery cell and improving the energy density of the battery cell.
Specifically, the first tabs are distributed on the at least two straight portions, that is, at least two tabs are respectively distributed on different straight portions, for example, when the number of the tabs is two, the two tabs are respectively distributed on different straight portions. In the order of straight portions in the winding direction of the electrode structure, n straight portions (denoted as second straight portions) without the first tab are located between every two adjacent straight portions (denoted as first straight portions) with the first tab, which is equivalent to the order from one end of the electrode structure to the other end thereof before the electrode structure is wound, n second straight portions are located between every two of all the first straight portions, preferably, n may include at least one of 1, 3, and 5, as shown in fig. 4, the number of the first straight portions is two, 1 (i.e., n is 1) second straight portion is located between the two first straight portions, and when the number of the first straight portions is more than two, the number of the second straight portions located between every two of all the first straight portions may be the same or different, for example, the number of the first straight portions is three, and the straight portions in the winding direction are sequentially denoted as first straight portions a, b, c, and d, The number of the second straight parts between the first straight parts A and B is n1, the number of the second straight parts between the first straight parts B and C is n2, n1 and n2 are respectively taken from one of 1, 3 and 5, n1 and n2 can be the same or different, for example, n1 and n2 are both 1, or n1 is 1 and n2 is 3.
Specifically, taking the straight portion of the winding start end of the electrode structure as the first straight portion (the first straight portion is located at the innermost circle of the wound structure/cell), calculating the order of the straight portions along the winding direction from inside to outside of the wound structure, the first tabs may be distributed on odd number of straight portions, for example, at least two of the first straight portion, the third straight portion, the fifth straight portion, and the seventh straight portion (as shown in fig. 1 to 4, two first tabs of the electrode structure are distributed on the first straight portion and the third straight portion), the first tabs may also be distributed on even number of straight portions, for example, at least two of the second straight portion, the fourth straight portion, the sixth straight portion, and the eighth straight portion, in some embodiments, calculating the order of the straight portions along the winding direction from inside to outside of the wound structure with the straight portion of the winding start end of the electrode structure as the first straight portion, the straight part which is positioned at the innermost side of the battery cell and provided with the first lug is the mth straight part, and m is more than or equal to 3.
In some embodiments, projections of every two first tabs of all the first tabs of the electrode structure on a first plane are at least partially overlapped (as shown in fig. 6), the first plane is a plane parallel to a surface of a straight current collector in the winding structure, and the first plane is perpendicular to a width direction of the winding structure and parallel to a length direction of the winding structure, so that the sheet resistance of the battery cell is further reduced, and meanwhile, the welding of the first tabs and external tabs is facilitated, the battery cell space is saved, and the energy density of the battery cell is improved.
Specifically, the distribution of the first tab on the electrode structure satisfies: in the winding structure, the projections of every two first tabs on the first plane at least partially overlap, that is, the projection of each first tab on the first plane at least partially overlaps with the projection of each of the rest first tabs on the first plane, and the at least partial overlap satisfies the following conditions: k is w1/w2, k is equal to or greater than 80%, k represents the degree of overlap, w1 is the width of the overlap of the projections of the two first tabs on the first plane in the first direction, w2 is the width of the first tab in the first direction, and the first direction is the direction from the bent portion at one end of the straight portion to the bent portion at the other end of the straight portion (generally, the longitudinal direction of the straight portion/wound structure/wound cell). For example, the electrode structure is provided with three first tabs, which are respectively referred to as a first tab a, a first tab B, and a first tab C, and the overlapping degree of the first tab a and the first tab B, the overlapping degree of the first tab a and the first tab C, and the overlapping degree of the first tab B and the first tab C are not less than 80%. In general, the widths of all the first tabs are substantially the same in the electrode structure, when the widths of the first tabs are different, and the degree of overlap (the degree of overlap AB) of the first tab a with respect to the first tab B is calculated by k-w 1/w2, w2 may specifically refer to the width of the first tab a in the first direction, and when the degree of overlap (denoted as the degree of overlap BA) of the first tab B with respect to the first tab a is calculated by k-w 1/w2, w2 refers to the width of the first tab B in the first direction, and the degree of overlap AB and the degree of overlap BA are not less than 80%.
In the invention, an active substance layer can be arranged on one surface of the current collector, and active substance layers can also be arranged on the front surface and the back surface of the current collector, so that the active substance layer is beneficial to further improving the performances of energy density and the like of the battery. When the positive and negative surfaces of the current collector are provided with active material layers, the positive and negative surfaces of the current collector of at least part of the bent parts of the electrode structure are provided with active material layers, and preferably, the positive and negative surfaces of the current collector of all the bent parts are provided with active material layers; both the front and back surfaces of the current collector of at least part of the straight parts in all the straight parts of the electrode structure are provided with active material layers, preferably both the front and back surfaces of the current collector of the straight part provided with the first tab are provided with active material layers, and more preferably both the front and back surfaces of the current collector of all the straight parts are provided with active material layers (as shown in fig. 4).
When only one surface of the current collector is provided with the active substance layer, the first electrode lug is arranged on the surface of the straight part of the current collector with the active substance layer, and the at least two first electrode lugs are respectively positioned on different straight parts; when both surfaces of the current collector are provided with the active material layers, the first tabs can be arranged on one surface of the current collector (namely, the first tabs in the electrode structure are positioned on the same surface of the current collector), or the first tabs can be distributed on both surfaces of the current collector (namely, the first tabs in the electrode structure are distributed on the positive and negative surfaces of the current collector), relatively speaking, the positive and negative surfaces of the electrode structure are directly connected with the first tabs, the current distribution is more uniform, and the internal resistance of the battery can be further reduced. The first tab arranged on one surface of the current collector and the first tab arranged on the other surface of the current collector can be positioned on the same straight part or different straight parts. In the present invention, one of the front and back surfaces (i.e., the above-mentioned one surface and the other surface) of the current collector refers to a surface of the current collector facing the inside of the winding structure (cell), and the other refers to a surface of the current collector facing away from the inside of the winding structure (i.e., a surface facing the outside of the winding structure).
For example, as shown in fig. 1 to 3, the electrode structure is provided with two first tabs respectively located on the front and back surfaces of the current collector and located on different straight portions, where fig. 1 is a schematic structural view of the first surface of the electrode structure before winding, fig. 2 is a schematic structural view of the second surface of the electrode structure before winding, the first surface is opposite to the second surface (i.e. the front and back surfaces of the electrode structure respectively), and from the left end (the winding start end of the electrode structure) of fig. 1 and 2, the first surface of the current collector of the first straight portion has an empty foil area, the second surface of the current collector of the third straight portion has an empty foil area, and the two first tabs are respectively located in the empty foil area of the first surface of the first straight portion and the empty foil area of the second surface of the third straight portion (the first tabs are not shown in fig. 1 and 2, fig. 3 is a schematic structural diagram of the first tab welded in the empty foil area of the first surface of the electrode structure), that is, one first tab is located on the first straight portion, and the other first tab is located on the third straight portion.
In some preferred embodiments, both surfaces of at least one current collector provided with a straight portion of the first tab are provided with the first tab, and more preferably both surfaces of each current collector provided with a straight portion of the first tab are provided with the first tab. Specifically, each straight portion provided with the first tab may have one or two tabs, and when there are two tabs, the two tabs are respectively disposed on the front and back surfaces of the current collector of the straight portion.
In some embodiments, in the electrode structure, a ratio of the number of the straight portions to the number of the first tabs may be 3 to 10:1, e.g., 3:1, 5:1, 7:1, 10:1, or any two ratio thereof. Generally, the number of the straight parts in the electrode structure is 8-30, and the number of the bending parts is one less than that of the straight parts.
In the present invention, the current collector is formed by laminating a metal layer, a polymer layer and a metal layer, the polymer layer is used as a substrate layer and is spaced between two metal layers which are used as conductive layers, in some embodiments, the metal layer of the current collector may be a layer (or called a film) formed by a metal or an alloy, specifically, the metal layer may include at least one of aluminum, copper, nickel, silver, gold and iron, for example, a conventional aluminum foil, a conventional copper foil, and the like, and the two metal layers in the current collector may be the same or different, and preferably, the same. The polymer layer is formed of a polymer, and may generally include at least one of polyethylene terephthalate (PET), PP (polypropylene), PE (polyethylene), PI (polyimide), PEK (polyether ketone), and PPs (polyphenylene sulfide). The metal layer and the polymer layer may be continuous (i.e., substantially void-free) or porous, and the present invention is not particularly limited in this regard. In addition, a transition layer may or may not be present between the metal layer and the polymer layer, where the transition layer includes at least one of aluminum oxide, magnesium oxide, and titanium oxide, a transition layer may be present between one of the two metal layers of the current collector and the polymer layer (i.e., the current collector includes the metal layer, the transition layer, the polymer layer, and the metal layer, which are sequentially stacked), or a transition layer may be present between both the two metal layers and the polymer layer (i.e., the current collector includes the metal layer, the transition layer, the polymer layer, the transition layer, and the metal layer, which are sequentially stacked).
In the invention, the structure of the positive plate can be the electrode structure, or the structure of the negative plate can be the electrode structure, or the structures of the positive plate and the negative plate can be the electrode structures; when the structure of the positive plate is the above electrode structure, correspondingly, the current collector is a positive current collector (for example, including an aluminum foil), the first tab is a positive tab, the external tab is a positive external tab, and the active material layer is a positive active material layer, where the negative plate may be a conventional negative plate in the art (for example, a negative plate with a copper foil as a current collector and a tab number of 1); when the structure of the negative electrode sheet is the above electrode structure, correspondingly, the above current collector is a negative electrode current collector (for example, including a copper foil), the above first tab is a negative electrode tab, and the above active material layer is a negative electrode active material layer, at this time, the positive electrode sheet may be a positive electrode sheet conventional in the art (for example, a positive electrode sheet with an aluminum foil as a current collector and a tab number of 1); when the structure of positive plate and negative pole piece all was above-mentioned electrode structure, above-mentioned external utmost point ear includes the external utmost point ear of anodal and the external utmost point ear of negative pole, and the welding of the external utmost point ear of anodal utmost point ear and anodal on the positive plate is in the same place, and the welding of the external utmost point ear of negative pole and negative pole on the negative pole piece is in the same place.
In general, the active material layer includes an active material, a conductive agent and a binder, optionally, the conductive agent may include at least one of conductive carbon black, carbon nanotubes, conductive graphite and graphene, the binder includes at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene and styrene butadiene rubber, when the electrode structure is a positive electrode sheet, the active material is a positive active material, and the positive active material may include Lithium Cobaltate (LCO), nickel cobalt manganese ternary material (NCM), nickel cobalt aluminum ternary material (NCA), nickel cobalt manganese quaternary material (NCMA), lithium iron phosphate (LFP), manganese phosphate (LMP), Lithium Vanadium Phosphate (LVP), vanadium phosphate (LVP), And when the electrode structure is a negative electrode sheet, the active material is a negative electrode active material, the negative electrode active material comprises at least one of graphite, mesocarbon microbeads, soft carbon, hard carbon, silicon material, silica material, silicon carbon material and lithium titanate, and the active material layer can further contain a dispersing agent, and the dispersing agent comprises sodium carboxymethylcellulose (CMC-Na) and the like. However, the composition of the active material layer of the present invention is not limited thereto.
The electrode structure of the present invention may be manufactured according to a conventional method in the art, for example, by placing the active material, the conductive agent and the binder in a solvent to prepare a slurry, coating the slurry on the surface of the current collector, drying and rolling the slurry to form an active material layer, selecting a blank region on the electrode structure according to the distribution requirement of the first tab, scraping the active material layer in the blank region, and welding the first tab to the blank region to obtain the electrode structure.
Specifically, the winding type battery cell further includes a separator located between the positive electrode sheet and the negative electrode sheet, the separator being used for separating the positive electrode sheet and the negative electrode sheet, and may be a separator that is conventional in the art, and the invention is not particularly limited thereto.
The electrochemical device of the present invention may be a battery, such as a lithium ion battery, and may be manufactured according to a conventional method in the art, for example, a positive plate, a separator, and a negative plate are sequentially stacked, wound to form a wound electrical core (wherein both the positive plate and the negative plate form a wound structure), and then subjected to processes such as packaging, liquid injection, formation, secondary sealing, and capacity grading, so as to manufacture a battery, where the steps/processes are conventional operations in the art and are not described in detail.
In a specific embodiment of the present invention, as shown in fig. 1 to 6, an electrochemical device includes a wound battery cell, the wound battery cell includes a first electrode sheet 11, a second electrode sheet 12, and a separator 13 located between the first electrode sheet 11 and the second electrode sheet 12, one of the first electrode sheet 11 and the second electrode sheet 12 is a positive electrode sheet, the other is a negative electrode sheet, and the structure of the first electrode sheet 11 is the above-mentioned electrode structure, where fig. 1 is a schematic structural diagram of a first surface (front side) of the first electrode sheet, fig. 2 is a schematic structural diagram of a second surface (back side) of the first electrode sheet, fig. 3 is a schematic structural diagram of the first electrode sheet with a first tab welded on the front side, fig. 4 is a schematic structural diagram of the wound battery cell formed by winding the first electrode sheet and the second electrode sheet, fig. 5 is a schematic cross-sectional diagram of an area surrounded by a dotted line x in fig. 4, fig. 6 is a schematic diagram illustrating a cell structure of the overlapping portion 7 of the first tab of the first electrode sheet. The first electrode plate comprises a first current collector 1 and a first active material layer 2 positioned on the surface of the first current collector 1, wherein the first current collector 1 comprises two metal layers and a polymer layer positioned between the two metal layers; the first electrode sheet has at least three straight portions 3 and a bent portion 4 connected between every two adjacent straight portions, and in the winding type battery cell, the first electrode sheet is bent by the bent portion 4 to form a winding type structure (as shown in fig. 4); the positive and negative surfaces of the current collector of all the straight parts and the bent parts of the first electrode plate are provided with first active material layers; the first electrode plate 11 has two first tabs 5, a straight portion of the first electrode plate 11 located at an initial end of an innermost ring of the battery cell is taken as a first straight portion, one first tab is arranged on a first surface of the first straight portion 31, the other first tab is arranged on a second surface of a third straight portion 33 (namely n is 1, and the front surface and the back surface of a current collector of the first electrode plate are both provided with the first tabs), the first surface is a surface of the first straight portion deviating from the inner side of the battery cell, the second surface is a surface of the third straight portion facing the inner side of the battery cell, and the overlapping degree k of the two first tabs 5 is more than or equal to 90%; correspondingly, the first surface of the first straight part 31 and the second surface of the third straight part 33 are provided with a hollow foil area 6, the hollow foil area 6 is rectangular, one side of the hollow foil area is in the same straight line with the long side of the surface of the first current collector, and the other three sides are connected with the first active material layer 2; a first tab 5 is welded on the surface of the current collector of the empty foil area 6; the winding type battery cell further comprises an external tab 8, two first tabs 5 on the first electrode plates are welded with the external tab, in the direction perpendicular to the surface of the current collector of the straight portion, a first straight portion 31 is located on the first side of the external tab 8, a third straight portion 33 is located on the second side of the external tab 8, and in the direction perpendicular to the surface of the current collector of the straight portion, the distance from the first straight portion 31 to the external tab 8 is substantially equal to the distance from the third straight portion 33 to the external tab 8 (namely, the external tab 8 is located between the first straight portion 31 and the third straight portion 33, as shown in fig. 5); first utmost point ear 5 includes first connecting portion 51 and second connecting portion 52, first utmost point ear passes through first connecting portion 51 welding and gathers the body surface at empty foil district 6, and the body outer fringe is stretched out to one side of first connecting portion 51, all the other sides are surrounded by active substance layer 2, the one end of second connecting portion 52 links to each other with first connecting portion 51, the other end and the external utmost point ear 8 welding of second connecting portion 52, first connecting portion 51, second connecting portion 52, external utmost point ear 8 is straight type structure, the length of weld part 9 by this welding formation on external utmost point ear 8 length direction is 0.2 ~ 2mm, it has utmost point ear glue 10 to paste between the one end of external utmost point ear 8 to the other end. The second electrode sheet 12 comprises a second current collector 1 ' and a second active material layer 2 ' located on the surface of the second current collector, the second current collector 1 ' may be a metal foil, the second electrode sheet 12 has a second tab 5 ', in the wound battery cell, the straight portion of the second electrode sheet located at the starting end of the innermost circle of the battery cell is taken as a first straight portion 31 ', and the second tab 5 ' is arranged on a fourth straight portion 34 ' of the second electrode sheet 12; wherein, the first straight portion 31 'of second electrode slice and connect and do not all be equipped with active substance layer on two surfaces of the mass flow body of the kink between first straight portion 31' and the second straight portion, the second straight portion of second electrode slice, the third straight portion, and connect the kink between the second straight portion and the third straight portion, a surface of the mass flow body of the kink of connecting between third straight portion and fourth straight portion is equipped with second active substance layer, another surface is not equipped with second active substance layer (generally the surface that deviates from the inboard of electric core is equipped with second active substance layer, and the surface to the inboard of electric core is not equipped with second active substance layer).
To make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the following examples and comparative examples, the cell performance was tested according to the following procedure:
(1) measuring the energy density of the battery: charging the battery to an upper limit voltage by 0.5C current, then charging at a constant voltage, stopping current of 0.05C, then discharging the fully charged battery to 3.0V by 0.5C current, and recording the discharged energy as the energy E of the battery; weighing the mass of the battery by using an electronic balance, wherein the mass is recorded as W, and the mass energy density EDW of the battery is recorded as E/W; measuring the length a, the width b and the thickness c of the battery, wherein the volume energy density EDV of the battery is E/V, and V is a multiplied by b multiplied by c;
(2) and (3) determining the rate performance of the battery: charging the battery to an upper limit voltage by 0.2C current, then charging at a constant voltage, stopping current of 0.02C, then discharging the fully charged battery to 3.0V by 0.2C current, and recording the discharge capacity as initial capacity C0; then the battery is charged to the upper limit voltage by 0.2C current, then the battery is charged at constant voltage, the current is cut off by 0.02C, then the fully charged battery is discharged to 3.0V by 1C current, the discharge capacity is recorded as 1C rate capacity C1, and the rate performance of the battery is represented by the ratio of C1 to C0 (C1/C0) (the larger C1/C0 is, the better rate performance of the battery is shown);
(3) measuring internal resistance: the battery was charged to 50% SOC (i.e., the battery was charged to half its capacity), and then the internal resistance of the battery was tested using a 1000Hz voltage-internal resistance tester.
In the following examples and comparative examples, the first surface of the straight portion is a surface of the wound cell in which the straight portion faces the inside of the cell, and the second surface is opposite to the first surface, that is, the second surface is a surface of the wound cell in which the straight portion faces away from the inside of the cell.
Example 1
In this embodiment, the electrochemical device is a wound lithium ion battery, which includes a wound cell, where the wound cell includes a first electrode sheet and a second electrode sheet; wherein,
the first electrode plate comprises a first current collector and a first active material layer positioned on the surface of the first current collector, wherein the first current collector comprises two metal layers and a polymer layer positioned between the two metal layers;
the first electrode plate is provided with 18 straight parts and a bent part connected between every two adjacent straight parts, and in the winding type battery cell, the first electrode plate is bent through the bent part to form a winding type structure; the positive and negative surfaces of the current collector of all the straight parts and the bent parts of the first electrode plate are provided with first active material layers;
the first electrode plate is provided with two first electrode lugs, a straight part of the first electrode plate, which is positioned at the initial end of the innermost ring of the battery cell, is taken as a first straight part, one first electrode lug is arranged on the first surface of the third straight part, the other first electrode lug is arranged on the second surface of the fifth straight part (namely n is 1, the positive surface and the negative surface of the current collector of the first electrode plate are both provided with the first electrode lugs), and the overlapping degree k of the two first electrode lugs is about 90%;
correspondingly, the first surface of the third straight part and the second surface of the fifth straight part are respectively provided with a hollow foil area, the hollow foil areas are rectangular, one side of each hollow foil area is in the same straight line with the long side of the surface of the first current collector, and the other three sides of each hollow foil area are connected with the first active material layer; the first tab is welded on the surface of the current collector in the hollow foil area;
the winding type battery cell also comprises an external tab, wherein two first tabs on the first electrode plates are welded with the external tab, in the direction perpendicular to the surface of the straight current collector, the third straight part is positioned on the first side of the external tab, the fifth straight part is positioned on the second side of the external tab, and in the direction perpendicular to the surface of the straight current collector, the distance from the third straight part to the external tab is basically equal to the distance from the fifth straight part to the external tab 8 (namely the external tab is positioned between the third straight part and the fifth straight part); the first tab comprises a first connecting part and a second connecting part, the first tab is welded on the surface of the current collector in the hollow foil area through the first connecting part, one side of the first connecting part extends out of the outer edge of the current collector, the other sides of the first connecting part are surrounded by the active material layer, one end of the second connecting part is connected with the first connecting part, the other end of the second connecting part is welded with the external tab, the first connecting part, the second connecting part and the external tab are all of a straight structure, the length of the welding part formed by welding in the length direction of the external tab is 0.5mm, and first tab glue is adhered between one end of the external tab and the other end of the external tab;
the second electrode plate comprises a second current collector and a second active substance layer positioned on the surface of the second current collector, the second electrode plate is provided with a second tab, in the coiled battery cell, the straight part of the second electrode plate positioned at the starting end of the innermost circle of the battery cell is taken as a first straight part, and the second tab is arranged on the fifth straight part of the second electrode plate; wherein, the first straight portion of second electrode slice, and connect and do not all be equipped with the second active material layer on two surfaces of the mass flow body of the kink between first straight portion and the second straight portion, the second straight portion of second electrode slice, the third straight portion, and connect the kink between second straight portion and third straight portion, the mass flow body of the kink of connecting between third straight portion and fourth straight portion deviates from the inboard surface of electric core and is equipped with the active material layer, do not be equipped with the active material layer towards the inboard surface of electric core.
The first electrode plate, the second electrode plate, the battery cell and the lithium ion battery of the embodiment are prepared as follows:
mixing a first active substance, conductive carbon black and polyvinylidene fluoride according to a mass ratio of 97: 1.5: 1.5, placing the mixture into a first solvent, and uniformly mixing to prepare first slurry; coating the first slurry on the front surface and the back surface of a first current collector, drying and rolling to form a first active substance layer, selecting a blank foil area according to the preset distribution position of a first tab, removing the first active substance layer in the blank foil area by using a scraper, and welding the first tab in the blank foil area to obtain a first electrode plate;
mixing a second active substance, conductive carbon black, polyvinylidene fluoride and sodium carboxymethylcellulose according to a mass ratio of 95: 2: 1.5: 1.5, placing the mixture into a second solvent, and uniformly mixing to prepare second slurry; and coating the second slurry on the front surface and the back surface of the second current collector, drying and rolling to form a second active substance layer, selecting a hollow foil area according to the preset position of the second tab, cleaning the second active substance layer in the hollow foil area, and welding the second tab in the hollow foil area to obtain a second electrode plate.
And sequentially stacking the first electrode plate, the diaphragm and the second electrode plate, winding to form a winding type battery cell, and then carrying out processes of packaging, liquid injection, formation, secondary sealing, capacity grading and the like to obtain the lithium ion battery.
In this embodiment, the first electrode sheet is a positive electrode sheet, the metal layer of the first current collector is an aluminum layer formed of aluminum, the polymer layer is a PET layer formed of PET (that is, the positive electrode current collector is a foil material with an Al-PET-Al structure), the first active material is lithium cobaltate, and the first solvent is N-methylpyrrolidone (NMP); the second electrode plate is a negative plate, the second current collector is copper foil, the second active substance is graphite, and the second solvent is deionized water.
Example 2
The difference between this embodiment and embodiment 1 is that the first electrode sheet has 4 first tabs, two of which are respectively located on the first surface and the second surface of the third straight portion, and the other two of which are respectively located on the first surface and the second surface of the fifth straight portion, where the overlapping degree k of any two of the first tabs is about 90%; the remaining conditions were the same as in example 1.
Example 3
The difference between the present embodiment and embodiment 1 is that the first electrode plate has 3 first tabs, which are respectively disposed on the first surface of the third straight portion, the second surface of the fifth straight portion, and the second surface of the seventh straight portion, wherein the overlapping degree k of any two first tabs is about 80%, the first tabs in the first electrode plate are welded to one end of the external tab, and the length of the welded portion formed by the welding in the length direction of the external tab is 1 mm; the remaining conditions were the same as in example 1.
Example 4
The difference between the present embodiment and embodiment 1 is that the first electrode sheet has 6 first tabs, which are respectively disposed on the first surface and the second surface of the third straight portion, the first surface and the second surface of the fifth straight portion, and the first surface and the second surface of the seventh straight portion, wherein the overlapping degree k of any two first tabs is about 80%, the first tabs in the first electrode sheet are welded to one end of the external tab, and the length of the welding portion formed by the welding in the length direction of the external tab is 1 mm; the remaining conditions were the same as in example 1.
Example 5
The difference between this embodiment and embodiment 1 is that the first electrode sheet is a negative electrode sheet, the metal layer of the first current collector is a copper layer formed by copper, the polymer layer is a PET layer formed by PET (that is, the negative electrode current collector is a foil with an Al-PET-Al structure), the first active material is graphite, and the first solvent is deionized water; the second electrode plate is a positive plate, the second current collector is aluminum foil, the second active material is lithium cobaltate, and the second solvent is NMP.
Comparative example 1
This comparative example 1 is different from example 1 in that the first current collector is an aluminum foil, and the remaining conditions are the same as example 1.
Comparative example 2
The comparative example 2 is different from the example 1 in that two first tabs on the first electrode sheet are welded to the first surface of the third straight portion and the first surface of the fifth straight portion respectively (i.e., one surface of the current collector of the first electrode sheet is provided with the first tab, and the other surface is not provided with the first tab), and the rest conditions are the same as those of the example 1.
Comparative example 3
This comparative example 3 is different from example 1 in that the first electrode sheet has two first tabs welded to the end of the first current collector, that is, one side of the empty foil zone to which the first tabs are welded is connected to the first active material layer, and the remaining three sides are respectively aligned with three sides of the surface of the first current collector (as shown in fig. 7), and the rest of the conditions are the same as those in example 1.
Comparative example 4
The difference between this comparative example 4 and example 1 is that, in the winding-type battery core, the first electrode sheet is not welded with the first tab, but the first current collectors of the third straight portion and the fifth straight portion of the first electrode sheet extend outward and are welded with the external tab after being bent, and the two first tabs are located on the same side of the external tab, rather than on the first side and the second side of the external tab (as shown in fig. 8).
Comparative example 5
This comparative example 5 is different from example 5 in that the first current collector is a copper foil, and the remaining conditions are the same as example 5.
The mass energy density, the volume energy density, and C1/C0 characterizing the rate-doubling performance of the batteries of the respective examples and comparative examples were measured and are shown in Table 1.
TABLE 1
As can be seen from comparison between example 1 and comparative example 1, the first electrode plate in example 1 adopts a coated current collector, so that the mass energy density is significantly improved, and lower internal resistance and good rate performance can be maintained; in addition, the safety performance of the battery of example 1 was also significantly better than that of comparative example 1;
as can be seen from the comparison between the example 1 and the comparative example 2, the two first tabs in the example 1 are respectively arranged on the front surface and the back surface of the first current collector, so that the energy density of the battery can be remarkably improved, and the internal resistance can be reduced;
comparing example 1 with comparative example 3, it can be seen that the first tab in example 1 is disposed in the middle of the first current collector, only one side of the first tab extends out of the outer edge of the first current collector, and the other three sides are surrounded by the first active material layer, so that the energy density of the battery can be improved, the internal resistance can be reduced, and the rate capability of the battery can be improved;
comparing example 1 with comparative example 4, it can be seen that the connection mode of the first tab and the external tab in example 1 can not only save the cell space and improve the volume energy density, but also reduce the internal resistance and improve the rate capability of the battery;
comparing example 5 with comparative example 5, it can be seen that the first electrode plate in example 5 adopts a coated current collector, so that the mass energy density is significantly improved, and meanwhile, the low internal resistance and the good rate performance can be maintained; in addition, the safety performance of the battery of example 5 was also significantly better than that of comparative example 5, as tested.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The winding type battery cell is characterized by comprising a positive plate and a negative plate, wherein at least one of the positive plate and the negative plate has the following electrode structure:
the electrode structure comprises a current collector and an active substance layer positioned on at least one surface of the current collector, wherein the current collector comprises two metal layers and a polymer layer positioned between the two metal layers;
the electrode structure is provided with at least three straight parts and a bending part connected between every two straight parts, and the electrode structure is bent through the bending part to form a coiled structure;
the electrode structure is equipped with two at least first utmost point ears, first utmost point ear sets up the mass flow body is equipped with the surface on active substance layer and distributes on the straight portion.
2. The wound battery cell of claim 1, further comprising an external tab, wherein one side of the first tab extends out of the outer edge of the current collector and is welded to the external tab, and the other sides of the first tab are surrounded by the active material layer.
3. The wound cell of claim 2, wherein a straight portion with a first tab is present on each of a first side and a second side of the external tab in a direction perpendicular to a current collector surface of the straight portion, the first side being opposite the second side.
4. A wound cell according to any of claims 1 to 3, wherein at least one of the following characteristics is met:
the first tabs are distributed on the at least two straight parts, n straight parts without the first tabs are arranged between every two straight parts with the first tabs in the winding direction of the electrode structure, and n is an odd number;
the projections of every two first lugs in the at least two first lugs on a first plane are at least partially overlapped, and the first plane is a plane parallel to the surface of the current collector of the straight part in the winding structure.
5. The wound cell of claim 4, wherein n comprises at least one of 1, 3, and 5.
6. The wound cell of claim 4, wherein the at least partial overlap satisfies: k is w1/w2, k is equal to or greater than 80%, k represents the degree of overlap, w1 is the width of the overlap of the projections of the two first tabs on the first plane in the first direction, w2 is the width of the first tab in the first direction, and the first direction is the direction from the bent portion at one end of the straight portion to the bent portion at the other end of the straight portion.
7. A wound cell according to claim 1,
the active material layers are arranged on the two surfaces of the current collector;
the two surfaces of the current collector of the electrode structure are distributed with the first lugs.
8. The battery according to claim 1,
the number ratio of the straight parts of the electrode structure to the first lugs is 3-10: 1; and/or the presence of a gas in the gas,
the number of straight parts of the electrode structure is 8-30.
9. A wound cell according to claim 1,
the metal layer comprises at least one of aluminum, copper, nickel, silver, gold and iron; and/or the presence of a gas in the gas,
the polymer layer comprises at least one of polyethylene terephthalate, polypropylene, polyethylene, polyimide, polyether ketone and polyphenylene sulfide; and/or the presence of a gas in the gas,
and a transition layer is arranged between the metal layer and the polymer layer or not, and the transition layer contains at least one of alumina, magnesia and titania.
10. An electrochemical device comprising a wound cell according to any of claims 1 to 9.
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