CN113285055B - Electrode slice and application thereof - Google Patents

Electrode slice and application thereof Download PDF

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Publication number
CN113285055B
CN113285055B CN202110594843.9A CN202110594843A CN113285055B CN 113285055 B CN113285055 B CN 113285055B CN 202110594843 A CN202110594843 A CN 202110594843A CN 113285055 B CN113285055 B CN 113285055B
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tab
area
current collector
region
active layer
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CN113285055A (en
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翟艳云
张健
彭冲
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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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
    • H01M4/13—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
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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)
  • Battery Electrode And Active Subsutance (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

The invention provides an electrode plate and application thereof. The first functional surface of the current collector in the electrode plate comprises a first active layer area and a first tab area, the second functional surface of the current collector comprises a second active layer area opposite to the first active layer area and a second tab area opposite to the first tab area, and the active layer is arranged in the first active layer area and/or the second active layer area; the first tab region is provided with N through holes penetrating to the second tab region, the T-shaped tab passes through the through holes, one end of a first section of the T-shaped tab is connected with the first tab region to form a first connecting region, the other end of the first section of the T-shaped tab is connected with the first tab region to form a second connecting region, the second section of the T-shaped tab is connected with the second tab region to form a third connecting region, and N is more than or equal to 1; the current collector includes a first conductive layer, an insulating layer, and a second conductive layer that are stacked. The lithium ion battery prepared by the electrode plate has higher quality energy density and safety performance.

Description

Electrode slice and application thereof
Technical Field
The invention relates to the technical field of batteries, in particular to an electrode plate and application thereof.
Background
Since the sony corporation of 1991 released the first commercial lithium ion battery, the lithium ion battery has been widely used in the fields of consumer electronics, electric automobiles, energy storage, and the like.
The existing lithium ion battery generally adopts aluminum foil as a positive electrode current collector and copper foil as a negative electrode current collector. To increase the energy density of lithium ion batteries, aluminum or copper foil may be combined with lighter weight polymeric materials to form new current collectors, such as aluminum-polymer-aluminum current collectors, copper-polymer-copper current collectors. The novel current collector with the sandwich structure has smaller surface density, can reduce the weight of the lithium ion battery and improve the energy density, and when the battery is short-circuited, the battery is heated to a certain temperature, and the polymer material can deform, so that a current loop is cut off, and the novel current collector has better safety than conventional copper foil and aluminum foil.
However, since the polymer material in the current collector having such a structure is not conductive, when the tab is welded to one surface of the current collector, the other surface of the current collector cannot be conducted, and thus a new welding method needs to be developed.
Disclosure of Invention
The invention provides an electrode plate which can be used for conducting two sides of a current collector and improving the quality energy density and the safety performance of a lithium ion battery.
The present invention provides an electrochemical device having high mass energy density and safety performance.
The invention provides an electrode slice, wherein the electrode slice comprises a current collector, an active layer and a T-shaped tab, a first functional surface of the current collector comprises a first active layer area and a first tab area, a second functional surface of the current collector comprises a second active layer area opposite to the first active layer area and a second tab area opposite to the first tab area, and the active layer is arranged in the first active layer area and/or the second active layer area;
the first tab region is provided with N through holes penetrating through the second tab region, the T-shaped tab passes through the through holes, one end of a first section of the T-shaped tab is connected with the first tab region to form a first connecting region, the other end of the first section of the T-shaped tab is connected with the first tab region to form a second connecting region, the second section of the T-shaped tab is connected with the second tab region to form a third connecting region, and N is more than or equal to 1;
the current collector comprises a first conductive layer, an insulating layer and a second conductive layer which are stacked;
The first functional surface is a surface of the first conductive layer far away from the insulating layer, and the second functional surface is a surface of the second conductive layer far away from the insulating layer.
An electrode sheet as described above, wherein either one end of the first segment or the second segment extends out of the current collector.
The electrode plate, wherein in the first direction of the current collector, the minimum distance between the edges of the M through holes and the edges of the current collector is W1, and W1 is more than or equal to 1mm; and/or the number of the groups of groups,
in the second direction of the current collector, the minimum distance between the edges of the M through holes and the edges of the first active layer area and/or the second active layer area is L1, wherein L1 is more than or equal to 2mm, and M is less than or equal to N.
The electrode sheet as described above, wherein, in the first direction of the current collector, a ratio of a minimum distance W1 of edges of the M through holes to edges of the current collector to a dimension W0 of the first tab region and/or the second tab region is (0.2-0.8): 1.
the electrode sheet as described above, wherein a ratio of an area of the through hole to a cross-sectional area of the second section is (1.2-50): 1.
the electrode sheet, wherein the minimum distance between the edge of the connecting area and the edge of the M through holes is more than or equal to 1mm in the first direction of the current collector;
Wherein the connection region comprises at least one of the first connection region, the second connection region, and the third connection region; and/or the number of the groups of groups,
in the first direction of the current collector, the minimum distance between the edge of the connecting area and the edge of the current collector is more than or equal to 1mm;
wherein the connection region includes at least one of the first connection region, the second connection region, and the third connection region.
The electrode sheet is characterized in that the first functional surface and/or the second functional surface are/is provided with protective layers, the protective layers cover the W through holes respectively, and the protective layers are provided with openings at the corresponding positions of the W through holes, wherein W is less than or equal to N.
The electrode sheet as described above, wherein the thickness of the protective layer is 0.5 to 50 μm.
The electrode sheet as described above, wherein the area of the protective layer is 1.2 to 5 times the area of the M through holes.
The invention also provides an electrochemical device, which comprises the electrode plate.
According to the invention, the through holes penetrating to the second lug area are formed in the first lug area, the T-shaped lugs penetrate through the through holes, and the two ends of the first section of the T-shaped lugs and the second section of the T-shaped lugs are respectively connected with the first lug area and the second lug area, so that the two sides of the current collector can be conducted, the quality energy density of the lithium ion battery is improved, the T-shaped lugs can better balance the stress around the through holes, the through holes are effectively prevented from cracking, the welding yield is improved, the service life of the electrode plate is prolonged, and the service life of the lithium ion battery is prolonged; more welding points can be formed among the T-shaped tab, the first tab area and the second tab area, welding resistance of the tab is reduced, and multiplying power charge-discharge performance of the lithium ion battery is improved. Meanwhile, the current collector comprises an insulating layer with lighter mass, so that the mass energy density of the lithium ion battery can be further improved; and when the temperature of the battery is raised to a certain temperature, the insulating layer can deform, so that the internal current of the battery is cut off, and the safety performance of the lithium ion battery is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related art, the drawings that are required to be used in the description of the embodiments of the present invention or the related technologies are briefly described below. It is evident that the drawings in the following description are only some embodiments of the present invention and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.
FIG. 1 is a top view of a current collector of the present invention;
FIG. 2 is a schematic diagram of a T-shaped tab according to the present invention;
fig. 3 is a top view of an electrode sheet in a first embodiment of the invention;
FIG. 4 is a first cross-sectional view taken along line X-X of FIG. 3 in accordance with the present invention;
FIG. 5 is a second cross-sectional view taken along line X-X of FIG. 3 in accordance with the present invention;
FIG. 6 is a top view of an electrode sheet according to a second embodiment of the present invention;
fig. 7 is a top view of an electrode sheet in a third embodiment of the present invention;
FIG. 8 is a cross-sectional view taken along line X-X of FIG. 6 or FIG. 7 in accordance with the present invention;
fig. 9 is a top view of an electrode sheet according to a fourth embodiment of the present invention;
FIG. 10 is a cross-sectional view taken along line X-X of FIG. 9 in accordance with the present invention;
FIG. 11 is a schematic view showing the structure of a winding core according to embodiment 1 of the present invention;
FIG. 12 is a schematic view showing the structure of a winding core according to embodiment 2 of the present invention;
fig. 13 is a schematic structural view of a winding core according to embodiment 3 of the present invention.
Reference numerals illustrate:
1: t-shaped lugs;
2: a first active layer region;
3: a first tab region;
4: a through hole;
5: a first connection region:
6: second ear region:
7: a second connection region;
8: a third connection region;
9: second active layer region
10: a protective layer;
1a: a first section;
1b: and a second section.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Fig. 1 is a top view of a current collector in the invention. As shown in fig. 1, all definitions of "length" and "width" are referred to as "length L direction" and "width W direction" of the current collector. Taking the first functional surface and/or the second functional surface (the first functional surface and the second functional surface refer to two largest and opposite surfaces of the current collector) of the current collector as an example, the length L direction of the current collector refers to the direction in which the largest side length of the functional surface of the current collector is located, and the width W direction of the current collector refers to the direction in which the smallest side length of the functional surface of the current collector is located. For example, the present invention defines the width of the first tab region and/or the second tab region as W0, which means that the dimension of the first tab region and/or the second tab region is W0 in the current collector width direction.
FIG. 2 is a schematic diagram of a T-shaped tab according to the present invention; fig. 3 is a top view of an electrode sheet in a first embodiment of the invention; FIG. 4 is a first cross-sectional view taken along line X-X of FIG. 3 in accordance with the present invention; FIG. 5 is a second cross-sectional view taken along line X-X of FIG. 3 in accordance with the present invention; fig. 6 is a top view of an electrode sheet in a second embodiment of the invention; fig. 7 is a top view of an electrode sheet in a third embodiment of the present invention; fig. 8 is a cross-sectional view taken along line X-X in fig. 6 or 7 in accordance with the present invention. As shown in fig. 2 to 8, the present invention provides an electrode sheet comprising a current collector, an active layer and a T-shaped tab 1, a first functional surface of the current collector comprising a first active layer region 2 and a first tab region 3, a second functional surface of the current collector comprising a second active layer region 9 opposite the first active layer region 2 and a second tab region 6 opposite the first tab region 3, the active layers being disposed in the first active layer region 1 and/or the second active layer region 9;
the first tab region 3 is provided with N through holes 4 penetrating to the second tab region 6, the T-shaped tab 1 passes through the through holes 4, one end of a first section 1a of the T-shaped tab 1 is connected with the first tab region 3 to form a first connecting region 5, the other end of the first section 1a of the T-shaped tab 1 is connected with the first tab region 3 to form a second connecting region 7, a second section 1b of the T-shaped tab 1 is connected with the second tab region 6 to form a third connecting region 8, and N is more than or equal to 1;
The current collector comprises a first conductive layer, an insulating layer and a second conductive layer which are stacked;
the first functional surface is a surface of the first conductive layer far away from the insulating layer, and the second functional surface is a surface of the second conductive layer far away from the insulating layer.
As shown in fig. 2, in the present invention, a first section 1a of a T-shaped tab 1 refers to a section of the T-shaped tab 1 that is horizontally disposed, and a second section 1b of the T-shaped tab 1 refers to a section of the T-shaped tab 1 that is vertically disposed, where the first section 1a and the second section 1b vertically intersect. The first section 1a of the T-shaped tab 1 is provided with two ends which are respectively positioned at two sides of the intersection point of the first section 1a and the second section 1 b.
The specific positions of the first tab region 3 and the first active layer region 2 are not limited by the present invention. As shown in fig. 3, the first tab region 3 of the present invention may be disposed at one side of the first active layer region 2 in the length direction; as shown in fig. 6, the first tab region 3 of the present invention may be disposed on one side of the first active layer region 2 in the width direction, and three sides of the first tab region 3 are adjacent to the first active layer region 2; as shown in fig. 7, the first tab region 3 of the present invention may be disposed on one side of the first active layer region 2 in the width direction, and one side of the first tab region 3 is adjacent to the first active layer region 2.
In the present invention, the second tab region 6 is disposed opposite to the first tab region 3, and the second active layer region 9 is disposed opposite to the first active layer region 2. It can be understood that the projection of the second tab area 6 on the first tab area 3 may completely coincide with the first tab area 3, and the projection of the second active layer area 9 on the first active layer area 2 may completely coincide with the first active layer area 2; the projection of the second tab region 6 onto the first tab region 3 may not completely overlap with the first tab region 3, and the projection of the second active layer region 9 onto the first active layer region 2 may not completely overlap with the first active layer region 2. The active layer of the present invention may be provided in the first active layer region 2, the second active layer region 9, or both the first active layer region 2 and the second active layer region 9.
In the invention, N through holes 4 penetrating to a second tab area 6 are arranged in a first tab area 3, and a T-shaped tab 1 passes through the through holes 4. It can be understood that the electrode plate of the invention can have N T-shaped lugs 1, N is less than or equal to N. When N is equal to N, each T-shaped tab 1 passes through one through hole 4, one end of the first section 1a of each T-shaped tab 1 is connected with the first tab area 3 to form a first connection area 5, the other end of the first section 1a of each T-shaped tab 1 is connected with the first tab area 3 to form a second connection area 7, and the second section 1b of each T-shaped tab 1 is connected with the second tab area 6 to form a third connection area 8; when N is smaller than N, each T-shaped tab 1 passes through one through hole 4, one end of the first section 1a of each T-shaped tab 1 is connected with the first tab area 3 to form a first connection area 5, the other end of the first section 1a of each T-shaped tab 1 is connected with the first tab area 3 to form a second connection area 7, the second section 1b of each T-shaped tab 1 is connected with the second tab area 6 to form a third connection area 8, and the remaining through holes 4 are reserved.
The invention is not limited to the shape of the through hole 4, and all the shapes which can enable the T-shaped tab 1 to pass through are within the protection scope of the invention. In some embodiments, the shape of the through-hole 4 may be rectangular, circular, polyhedral, elliptical, in particular embodiments, the shape of the through-hole 4 is elliptical.
The first connection region 5 in the present invention refers to a position where one end of the first segment 1a is fixed to the first tab region 3, the second connection region 7 refers to a position where the other end of the first segment 1a is fixed to the first tab region 3, and the third connection region 8 refers to a position where the second segment 1b is fixed to the second tab region 6. If the two ends of the first section 1a, the second section 1b, the first tab area 3 and the second tab area 6 of the T-shaped tab 1 are respectively fixed by welding, the first connection area 5 and the second connection area 7 are respectively areas where welding spots are located when the two ends of the first section 1a are welded with the first tab area 3, and the third connection area 8 is an area where welding spots are located when the second section 1b is welded with the second tab area 6.
In the invention, the first connecting area 5 and the second connecting area 7 are respectively positioned at two sides of the through hole in the width direction of the current collector; as shown in fig. 4, the third connection region 8 may be disposed on the same side as the first connection region 5, and as shown in fig. 5, the third connection region 8 may be disposed on the same side as the second connection region 7.
In the invention, the insulating layer comprises at least one of a high polymer material and a high polymer matrix composite material, namely the insulating layer can be a polymer layer;
further, the polymer material is at least one of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyoxymethylene, polyphenylene oxide, polyphenylene sulfide, polyethylene glycol, a sulfur nitride polymer material, polystyrene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, phenolic resin, derivatives thereof, crosslinked products thereof, and copolymers thereof.
The material of the first conductive layer and/or the second conductive layer includes at least one of a metal conductive material and a carbon-based conductive material.
Wherein the metallic conductive material may include at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, aluminum-zirconium alloy.
The carbon-based conductive material may include at least one of graphite, acetylene black, graphene, and carbon nanotubes.
When the material of the first conductive layer and/or the second conductive layer is a metal conductive material, the first conductive layer and/or the second conductive layer is a metal conductive layer. At this time, if the current collector is a positive current collector, aluminum is generally used as the metal conductive material; if the current collector is a negative current collector, copper is generally used as the metal conductive material. In the present invention, if the insulating layer is a polymer layer, the first conductive layer and the second conductive layer are both metal conductive layers.
The first conductive layer and the insulating layer and/or the second conductive layer and the insulating layer may further include a transition layer, and a material of the transition layer includes, but is not limited to, at least one of alumina, magnesia, or titania.
The first conductive layer, the second conductive layer, or the insulating layer may further be provided with a via hole. The present invention is not limited to the specific shape of the through hole, and the shape of the through hole may be rectangular, circular, polyhedral or elliptical, and in a specific embodiment, the shape of the through hole is elliptical.
According to the invention, the through holes 4 penetrating through the first lug area 3 and the second lug area 6 are formed in the current collector, the T-shaped lugs 1 penetrate through the through holes 4, the two ends of the first section 1a of each T-shaped lug are respectively connected with the first lug area 3, the second section 1b of each T-shaped lug 1 is connected with the second lug area 6, the two sides of the current collector can be conducted, the quality energy density of the lithium ion battery is improved, in addition, the T-shaped lugs 1 can well balance the stress around the through holes 4, the through holes 4 are effectively prevented from cracking, the service life of electrode plates is prolonged, and the service life of the lithium ion battery is prolonged; more welding points can be formed between the T-shaped tab 1 and the first tab area 3 and between the T-shaped tab 1 and the second tab area 6, welding resistance of the tabs is reduced, and rate charge and discharge performance of the lithium ion battery is improved. Meanwhile, the current collector comprises an insulating layer with lighter mass, so that the mass energy density of the lithium ion battery can be further improved; and when the temperature of the battery is raised to a certain temperature, the insulating layer can deform, so that the internal current of the battery is cut off, and the safety performance of the lithium ion battery is improved.
In the invention, any end of the first section 1a or the second section 1b extends out of the current collector for connection with the external tab.
In some embodiments of the invention, as shown in FIGS. 3-8, the minimum distance between the edges of the M through holes 4 and the edges of the current collector in the first direction of the current collector is W1, W1. Gtoreq.1 mm;
in the second direction of the current collector, the minimum distance between the edges of the M through holes and the edges of the first active layer region 2 and/or the second active layer region 9 is L1, wherein L1 is more than or equal to 2mm, and M is less than or equal to N.
In the present invention, the first direction of the current collector may be the width direction of the current collector or the length direction of the current collector. When the first direction of the current collector is the width direction of the current collector, the second direction of the current collector is the length direction of the current collector; when the first direction of the current collector is the length direction of the current collector, the second direction of the current collector is the width direction of the current collector.
In the invention, when the first direction of the current collector is the width direction of the current collector, the obtained electrode plate can be used for preparing the lithium ion battery with a winding structure; when the first direction of the current collector is the length direction of the current collector, the obtained electrode plate can be used for preparing a lithium ion battery with a laminated structure.
In the present invention, the minimum distance between the edge of the through hole 4 and the edge of the current collector refers to the distance between the edge of the closest through hole 4 and the edge of the current collector, and the minimum distance between the edge of the through hole 4 and the edge of the first active layer region 2 and/or the second active layer region 9 refers to the distance between the edge of the closest through hole 4 and the edge of the first active layer region 2 and/or the second active layer region 9. It will be understood that in the present invention, the minimum distance between the edges of at least M through holes 4 and the edges of the current collector in the first direction of the current collector is W1, W1. Gtoreq.1 mm, and the minimum distance between the edges of at least M through holes 4 and the edges of the first active layer region 2 and/or the second active layer region 9 in the second direction of the current collector is L1, L1. Gtoreq.2 mm. By this arrangement, the service life of the electrode sheet can be prolonged.
As shown in fig. 3 to 8, in some embodiments of the present invention, in the first direction of the current collector, the ratio of the minimum distance W1 of the edges of the M through holes 4 to the edges of the current collector to the dimension W0 of the first tab region 3 and/or the second tab region 6 is (0.2 to 0.8): 1.
in the invention, if the ratio of W1 to W0 is too large or too small, the through hole 4 is too close to the edge of the current collector, the electrode plate is easy to crack at the through hole in the long-term use process, the service life of the electrode plate is short, and the operability of welding is not facilitated. The invention defines the ratio of W1 to W0 as (0.2-0.8): 1, on the premise of guaranteeing the service life of the electrode plate, the welding operability can be facilitated.
In some embodiments of the invention, the ratio of the area of the through hole 4 to the cross-sectional area of the second section 1b is (1.2-50): 1.
in the present invention, the cross-sectional area of the second segment 1b refers to the area of the cross-section of the second segment 1b in the horizontal direction. In the invention, when the ratio of the area of the through hole 4 to the cross-sectional area of the second section 1b is too large, the spare area in the through hole 4 is too large, and the electrode plate is easy to damage in the long-term use process; when the ratio of the area of the through hole 4 to the cross-sectional area of the second section 1b is too small, the second section 1b easily cracks the through hole 4 during long-term use of the electrode sheet, reducing the service life of the electrode sheet. The present invention defines that the ratio of the area of the through hole 4 to the cross-sectional area of the second section 1b is (1.2-50): 1, in the range, the through hole 4 is not easy to crack, the electrode plate is not easy to damage in the long-term use process, and the electrode plate has longer service life. Further, the ratio of the area of the through hole 4 to the cross-sectional area of the second section 1b is (5-15): 1
Further, in order to extend the service life of the electrode sheet, in some embodiments of the present invention, in the first direction of the current collector, the minimum distance between the edge of the connection region and the edge of the M through holes 4 is equal to or greater than 1mm; wherein the connection region comprises at least one of a first connection region 5, a second connection region 7 and a third connection region 8; and/or the number of the groups of groups,
In the first direction of the current collector, the minimum distance between the edge of the connection region and the edge of the current collector is not less than 1mm, wherein the connection region comprises at least one of the first connection region 5, the second connection region 7 and the third connection region 8.
Fig. 9 is a top view of an electrode sheet according to a fourth embodiment of the present invention; fig. 10 is a cross-sectional view taken along line X-X of fig. 9 in accordance with the present invention. As shown in fig. 9 or 10, in some embodiments of the present invention, in order to protect the through holes 4, prevent the through holes 4 from cracking, and extend the service life of the electrode sheet, a protection layer 10 is provided on the first functional surface and/or the second functional surface, the protection layer 10 covers W through holes 4, respectively, the protection layer 10 has openings at corresponding positions of the W through holes 4, and W is less than or equal to N.
The specific type of the protective layer 10 is not limited in the present invention, and the protective layer 10 may be an insulating material or a conductive material. In particular embodiments, the protective layer 10 may be a protective gummed paper or ceramic layer. The corresponding positions of the W through holes 4 refer to the positions of the projections of the W through holes 4 on the protective layer 10. It will be understood that the protective layer 10 has openings at the through holes 4, and the size and shape of the openings of the protective layer 10 may be the same as the through holes 4 or may be different from the through holes 4.
In some embodiments of the present invention, the protective layer 10 has a thickness of 0.5-50 μm.
In the present invention, if the thickness of the protective layer 10 is too thick, the mass energy density of the electrode sheet is reduced, and if the thickness of the protective layer 10 is too thin, the through holes 4 cannot be sufficiently protected, and the service life of the electrode sheet is short. The thickness of the protective layer 10 is limited to be 0.5-50 mu m, so that the through hole 4 can be protected, the service life of the electrode plate can be prolonged, and the mass energy density of the electrode plate can not be reduced.
In some embodiments of the present invention, the area of the protective layer 10 is 1.2-5 times the area of the M through holes 4.
In the invention, if the area of the protective layer 10 (including the area of the opening of the protective layer 10) is too large, the quality energy density of the electrode plate is reduced, the connection between the T-shaped tab 1 and the first tab area 3 and/or the second tab area 6 is not facilitated, and if the area of the protective layer 10 is too small, the through hole 4 cannot be fully protected, and the service life of the electrode plate is short. The invention limits the area of the protective layer 10 to be 1.2-5 times of the area of the through hole 4, can ensure the quality energy density of the electrode slice, can ensure that the T-shaped electrode lug 1 is normally connected with the first electrode lug area 3 and/or the second electrode lug area 6, can also protect the through hole 4, and prolongs the service life of the electrode slice.
The electrode sheet of the present invention may be a positive electrode sheet or a negative electrode sheet.
When the electrode sheet is a positive electrode sheet, the active layer of the present invention is a positive electrode active layer provided on the surface of a positive electrode current collector. The positive electrode active layer is obtained by drying positive electrode active slurry, and the positive electrode active slurry comprises a positive electrode active material, a conductive agent and a binder; the positive electrode active material includes at least one of Lithium Cobalt Oxide (LCO), nickel cobalt manganese ternary material (NCM), nickel cobalt aluminum ternary material (NCA), nickel cobalt manganese aluminum quaternary material (NCMA), lithium iron phosphate (LFP), lithium Manganese Phosphate (LMP), lithium Vanadium Phosphate (LVP), lithium Manganate (LMO), or lithium-rich manganese group.
When the electrode sheet is a negative electrode sheet, the active layer of the present invention is a negative electrode active layer provided on the surface of a negative electrode current collector. The negative electrode active layer is obtained by drying a negative electrode active slurry, and the negative electrode active slurry comprises a negative electrode active material, a conductive agent and a binder; the negative electrode active material includes at least one of graphite, mesophase carbon microspheres, soft carbon, hard carbon, a silicon material, a silicon oxygen material, a silicon carbon material, or lithium titanate.
The conductive agent in the positive electrode active paste and the negative electrode active paste includes at least one of conductive carbon black, carbon nanotubes, conductive graphite, or graphene.
The binder in the positive electrode active paste and the negative electrode active paste includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, or styrene-butadiene rubber.
A second aspect of the present invention provides an electrochemical device comprising the electrode sheet described above, further comprising an exterior package and an electrolyte.
The outer package may be an aluminum plastic film, and the electrolyte may include a lithium salt and a nonaqueous solvent. In the present invention, the lithium salt is not particularly limited, and any lithium salt known in the art may be used as long as the object of the present invention can be achieved. For example, the lithium salt may include LiPF 6 、LiBF 4 、LiAsF 6 、LiClO 4 、LiB(C 6 H 5 ) 4 、LiCH 3 SO 3 、LiCF 3 SO 3 、LiN(SO 2 CF 3 ) 2 、LiC(SO 2 CF 3 ) 3 Or LiPO 2 F 2 At least one of them. In the present invention, the nonaqueous solvent is not particularly limited as long as the object of the present invention can be achieved. For example, the nonaqueous solvent may include a carbonate compound, a carboxylate compound, an ether compound, a nitrile compoundAt least one of other organic solvents.
The electrochemical device of the present invention can have high mass energy density and safety performance due to the inclusion of the electrode sheet.
The technical solutions of the present invention will be further described below with reference to specific examples, all parts, percentages, and ratios recited in the following examples are by weight, and all reagents used in the examples are commercially available or are synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the examples are commercially available.
Example 1
The lithium ion battery of this embodiment is obtained by the steps of:
1) Preparation of positive plate
The positive electrode current collector is a current collector with an Al-PET-Al structure, and as shown in fig. 9 and 10, the positive electrode current collector comprises a first tab area 3 and a first active layer area 2 in the length direction, a second tab area 6 is arranged corresponding to the first tab area 3, a second active layer area 9 is arranged corresponding to the first active layer area 2, the first tab area 3 is provided with a through hole 4 penetrating to the second tab area 6, and the shape of the through hole 4 is elliptical;
coating lithium cobaltate active slurry on the first active layer area 2 and the second active layer area 9, attaching protective gummed paper on the first tab area 3 and the second tab area 6, and then perforating the protective gummed paper at the position of the through hole 4, wherein the perforating shape is elliptic; wherein the mass composition of the lithium cobaltate active slurry is lithium cobaltate: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5 percent, the thickness of the protective gummed paper is 12 mu m, and the ratio of the area of the open hole of the gummed paper to the area of the through hole 4 is 1:1;
The T-shaped tab 1 made of Al is inserted into the through hole 4, one end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a first connecting area 5, the other end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a second connecting area 7, the second section 1b of the T-shaped tab 1 is welded in the second tab area 6 to form a third connecting area 8, the first connecting area 5 and the second connecting area 7 are positioned on two sides of the through hole 4, and the third connecting area 8 is on the same side as the first connecting area 5, so that the positive plate is obtained.
2) Preparation of negative electrode sheet
The negative electrode current collector is a Cu foil, graphite active slurry is coated on two surfaces of the negative electrode current collector, and electrode lugs are welded in areas where the graphite active slurry is not coated, so that a negative electrode plate is obtained;
the mass composition of the graphite active slurry is graphite: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1%.
3) Preparation of lithium ion batteries
Fig. 11 is a schematic structural view of a winding core according to embodiment 1 of the present invention. As shown in fig. 11, winding the positive plate in step 1), the negative plate in step 2) and the separator to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Example 2
The lithium ion battery of this embodiment is obtained by the steps of:
1) Preparation of positive plate
The positive current collector is Al-Al 2 O 3 -PET-Al 2 O 3 A current collector of Al structure, which includes a first tab region 3 and a first active layer region 2 in the width direction, three sides of the first tab region 3 being adjacent to the first active layer region 2, as shown in fig. 6 and 8; the second tab region 6 is arranged corresponding to the first tab region 3, the second active layer region 9 is arranged corresponding to the first active layer region 2, the first tab region 3 is provided with a through hole 4 penetrating to the second tab region 6, and the shape of the through hole 4 is elliptical;
applying lithium cobaltate active slurry to the first active layer region 2 and the second active layer region 9, wherein the mass composition of the lithium cobaltate active slurry is lithium cobaltate: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5%;
the T-shaped tab 1 made of Al is inserted into the through hole 4, one end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a first connecting area 5, the other end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a second connecting area 7, the second section 1b of the T-shaped tab 1 is welded in the second tab area 6 to form a third connecting area 8, the first connecting area 5 and the second connecting area 7 are positioned on two sides of the through hole 4, and the third connecting area 8 is on the same side as the first connecting area 5, so that the positive plate is obtained.
2) Preparation of negative electrode sheet
The negative electrode current collector is a Cu foil, graphite active slurry is coated on two surfaces of the negative electrode current collector, and nickel lugs are welded on any surface of the negative electrode current collector in an area without the graphite active slurry through ultrasonic welding, so that a negative electrode plate is obtained;
the mass composition of the graphite active slurry is graphite: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1%.
3) Preparation of lithium ion batteries
Fig. 12 is a schematic structural view of a winding core according to embodiment 2 of the present invention. As shown in fig. 12, winding the positive electrode sheet in step 1), the negative electrode sheet in step 2) and the separator to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Example 3
The lithium ion battery of this embodiment is obtained by the steps of:
1) Preparation of positive plate
The positive electrode current collector is a current collector of an Al-PP-Al structure, and as shown in fig. 7 and 8, the positive electrode current collector includes a first tab region 3 and a first active layer region 2 in the width direction, one side of the first tab region 3 being adjacent to the first active layer region 2; the second tab region 6 is arranged corresponding to the first tab region 3, the second active layer region 9 is arranged corresponding to the first active layer region 2, the first tab region 3 is provided with a through hole 4 penetrating to the second tab region 6, and the shape of the through hole 4 is elliptical;
Applying a lithium cobaltate active paste to the first active layer region 2 and the second active layer region 9; wherein the mass composition of the lithium cobaltate active slurry is lithium cobaltate: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5%;
the T-shaped tab 1 made of Al is inserted into the through hole 4, one end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a first connecting area 5, the other end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a second connecting area 7, the second section 1b of the T-shaped tab 1 is welded in the second tab area 6 to form a third connecting area 8, the first connecting area 5 and the second connecting area 7 are positioned on two sides of the through hole 4, and the third connecting area 8 is on the same side as the first connecting area 5, so that the positive plate is obtained.
2) Preparation of negative electrode sheet
The negative electrode current collector is a Cu foil, graphite active slurry is coated on two surfaces of the negative electrode current collector, and electrode lugs are welded in areas where the graphite active slurry is not coated, so that a negative electrode plate is obtained;
the mass composition of the graphite active slurry is graphite: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1%.
3) Preparation of lithium ion batteries
Fig. 13 is a schematic structural view of a winding core according to embodiment 3 of the present invention. As shown in fig. 13, winding the positive electrode sheet in step 1), the negative electrode sheet in step 2) and the separator to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Example 4
The lithium ion battery of this embodiment is obtained by the steps of:
1) Preparation of positive plate
The positive electrode current collector is an Al foil, lithium cobaltate active slurry is coated on two surfaces of the positive electrode current collector, and an aluminum tab is welded on any surface of the positive electrode current collector in an area without the lithium cobaltate active slurry through ultrasonic welding, so that a positive electrode plate is obtained;
the mass composition of the lithium cobaltate active slurry is as follows: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5%.
2) Preparation of negative electrode sheet
The negative electrode current collector is a current collector with a Cu-PET-Cu structure, and as shown in fig. 9 and 10, the negative electrode current collector comprises a first tab area 3 and a first active layer area 2 in the length direction, a second tab area 6 is arranged corresponding to the first tab area 3, a second active layer area 9 is arranged corresponding to the first active layer area 2, the first tab area 3 is provided with a through hole 4 penetrating to the second tab area 6, and the shape of the through hole 4 is elliptical;
coating graphite active slurry on the first active layer area 2 and the second active layer area 9, attaching protective gummed paper on the first tab area 3 and the second tab area 6, and then perforating the protective gummed paper at the position of the through hole 4, wherein the perforating shape is elliptic; wherein, the composition of the cathode active slurry is graphite: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1, the thickness of the protective gummed paper is 12 mu m, and the ratio of the area of an opening of the protective gummed paper to the area of the through hole 4 is 1:1;
The T-shaped tab 1 made of Ni is inserted into the through hole 4, one end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a first connecting area 5, the other end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a second connecting area 7, the second section 1b of the T-shaped tab 1 is welded in the second tab area 6 to form a third connecting area 8, the first connecting area 5 and the second connecting area 7 are positioned on two sides of the through hole 4, and the third connecting area 8 is on the same side as the first connecting area 5 to obtain the negative plate.
3) Preparation of lithium ion batteries
As shown in fig. 11, winding the positive plate in step 1), the negative plate in step 2) and the separator to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Example 5
The lithium ion battery of this embodiment is obtained by the steps of:
1) Preparation of positive plate
The positive electrode current collector is a current collector with an Al-PET-Al structure, and as shown in fig. 9 and 10, the positive electrode current collector comprises a first tab area 3 and a first active layer area 2 in the length direction, a second tab area 6 is arranged corresponding to the first tab area 3, a second active layer area 9 is arranged corresponding to the first active layer area 2, the first tab area 3 is provided with a through hole 4 penetrating to the second tab area 6, and the shape of the through hole 4 is elliptical;
Coating lithium cobaltate active slurry on the first active layer area 2 and the second active layer area 9, attaching protective gummed paper on the first tab area 3 and the second tab area 6, and then perforating the protective gummed paper at the position of the through hole 4, wherein the perforating shape is elliptic; wherein, the composition of the lithium cobaltate active slurry is lithium cobaltate: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5 percent, the thickness of the protective gummed paper is 12 mu m, and the ratio of the area of an opening of the protective gummed paper to the area of the through hole 4 is 1:1;
the T-shaped tab 1 made of Al is inserted into the through hole 4, one end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a first connecting area 5, the other end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a second connecting area 7, the second section 1b of the T-shaped tab 1 is welded in the second tab area 6 to form a third connecting area 8, the first connecting area 5 and the second connecting area 7 are positioned on two sides of the through hole 4, and the third connecting area 8 is on the same side as the first connecting area 5, so that the positive plate is obtained.
2) Preparation of negative electrode sheet
The negative electrode current collector is a current collector with a Cu-PET-Cu structure, and as shown in fig. 9 and 10, the negative electrode current collector comprises a first tab area 3 and a first active layer area 2 in the length direction, a second tab area 6 is arranged corresponding to the first tab area 3, a second active layer area 9 is arranged corresponding to the first active layer area 2, the first tab area 3 is provided with a through hole 4 penetrating to the second tab area 6, and the shape of the through hole 4 is elliptical;
Coating graphite active slurry on the first active layer area 2 and the second active layer area 9, attaching protective gummed paper on the first tab area 3 and the second tab area 6, and then perforating the protective gummed paper at the position of the through hole 4, wherein the perforating shape is elliptic; wherein, the composition of the cathode active slurry is graphite: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1, the thickness of the protective gummed paper is 12 mu m, and the ratio of the area of an opening of the protective gummed paper to the area of the through hole 4 is 1:1;
the T-shaped tab 1 made of Ni is inserted into the through hole 4, one end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a first connecting area 5, the other end of the first section 1a of the T-shaped tab 1 is welded in the first tab area 3 to form a second connecting area 7, the second section 1b of the T-shaped tab 1 is welded in the second tab area 6 to form a third connecting area 8, the first connecting area 5 and the second connecting area 7 are positioned on two sides of the through hole 4, and the third connecting area 8 is on the same side as the first connecting area 5 to obtain the negative plate.
3) Preparation of lithium ion batteries
As shown in fig. 11, winding the positive plate in step 1), the negative plate in step 2) and the separator to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Comparative example 1
The lithium ion battery of this comparative example was obtained by the following steps:
the positive electrode current collector is an Al foil, lithium cobaltate active slurry is coated on two sides of the positive electrode current collector, and a tab is welded in a region where the lithium cobaltate active slurry is not coated to obtain a positive electrode plate;
the negative electrode current collector is a Cu foil, graphite active slurry is coated on two sides of the negative electrode current collector, and tabs are welded in areas where the graphite active slurry is not coated to obtain a negative electrode plate;
the mass composition of the lithium cobaltate active slurry is as follows: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5 percent of graphite active slurry comprises the following components by mass: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1%;
winding the positive plate, the negative plate and the diaphragm to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Comparative example 2
The lithium ion battery of this comparative example was obtained by the following steps:
the positive electrode current collector adopts a current collector with an Al-PET-Al structure, lithium cobaltate active slurry is coated on two sides of the positive electrode current collector, and tabs are welded on any side of a region where the lithium cobaltate active slurry is not coated to obtain a positive electrode plate;
The negative electrode current collector is a Cu foil, graphite active slurry is coated on two sides of the negative electrode current collector, and tabs are welded in areas where the graphite active slurry is not coated to obtain a negative electrode plate;
the mass composition of the lithium cobaltate active slurry is as follows: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5 percent of graphite active slurry comprises the following components by mass: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1%;
winding the positive plate, the negative plate and the diaphragm to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Comparative example 3
The lithium ion battery of this comparative example was obtained by the following steps:
the positive electrode current collector is an Al foil, lithium cobaltate active slurry is coated on two sides of the positive electrode current collector, and a tab is welded in a region where the lithium cobaltate active slurry is not coated to obtain a positive electrode plate;
the negative electrode current collector adopts a current collector with an Al-PP-Al structure, graphite active slurry is coated on two sides of the negative electrode current collector, and lugs are welded on any side of a region where the graphite active slurry is not coated to obtain a negative electrode plate;
the mass composition of the lithium cobaltate active slurry is as follows: conductive carbon black: conductive carbon tube: pvdf=97%: 1%:0.5%:1.5 percent of graphite active slurry comprises the following components by mass: conductive carbon black: styrene-butadiene rubber: sodium carboxymethyl cellulose = 96%:1.5%:1.5%:1%;
Winding the positive plate, the negative plate and the diaphragm to obtain a winding core; and packaging, injecting liquid, forming, secondarily sealing and separating to obtain the lithium ion battery.
Performance testing
1) Weight impact test
The lithium ion battery is fully charged, the lithium ion battery is placed on a plane, a steel column with the diameter of 15.8+/-0.2 mm is placed at the center of the lithium ion battery, the longitudinal axis of the steel column is parallel to the plane, a weight with the mass of 9.1+/-0.1 kg is enabled to fall freely from the height of 610+/-25 mm onto the steel column above the lithium ion battery, 20 lithium ion batteries obtained in the same embodiment or comparative example are tested in parallel, and the weight impact passing rate of the lithium ion battery is calculated. The test results are shown in Table 1.
2) Mass energy density
The lithium ion battery was charged to full charge at 0.2C, then discharged to 3.0V at 0.2C, the discharge energy E thereof was recorded, and the mass of the battery was measured using an electronic balance and recorded as m. Mass energy density ed=e/m of the battery.
3) Welding impedance of positive electrode tab
And connecting the positive electrode of the internal resistance meter with the lug of the positive electrode plate to obtain a first contact point, connecting the negative electrode of the internal resistance meter with the non-lug part of the positive electrode plate to obtain a second contact point, keeping the two contact points and the first connecting area in the same straight line, and fixing the edge distance between the first contact point and the first connecting area to be 20mm.
4) Welding impedance of negative electrode tab
And connecting the negative electrode of the internal resistance meter with the lug of the negative electrode plate to obtain a first contact point, connecting the positive electrode of the internal resistance meter with the non-lug part of the negative electrode plate to obtain a second contact point, keeping the two contact points and the first connecting area in the same straight line, and fixing the edge distance between the first contact point and the first connecting area to be 20mm.
TABLE 1 results of battery performance tests for examples and comparative examples
As can be seen from table 1, the mass energy density of the lithium ion batteries of examples 1-5 of the present invention is greater than that of the lithium ion batteries of comparative examples, the weight impact performance of the lithium ion batteries of examples 1-3, 5 of the present invention is superior to that of the lithium ion batteries of comparative examples, the tab welding impedance of the positive electrode tab of examples 1-3, 5 of the present invention is lower than that of the positive electrode tab of comparative example 2, and the tab welding impedance of the negative electrode tab of examples 4-5 of the present invention is lower than that of the negative electrode tab of comparative example 3. Therefore, the lithium ion battery provided by the embodiment of the invention not only has high quality energy density, but also has good safety performance, and the welding impedance of the tab can be reduced by using the technical scheme of the invention.
In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments.
The foregoing is merely illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (8)

1. An electrode sheet, characterized in that the electrode sheet comprises a current collector, an active layer and a T-shaped tab, a first functional surface of the current collector comprises a first active layer area and a first tab area, a second functional surface of the current collector comprises a second active layer area opposite to the first active layer area and a second tab area opposite to the first tab area, and the active layer is arranged in the first active layer area and/or the second active layer area;
the first tab region is provided with N through holes penetrating through the second tab region, the T-shaped tab passes through the through holes, one end of a first section of the T-shaped tab is welded with the first tab region to form a first connecting region, the other end of the first section of the T-shaped tab is welded with the first tab region to form a second connecting region, the second section of the T-shaped tab is welded with the second tab region to form a third connecting region, and N is more than or equal to 1;
The first connecting area and the second connecting area are respectively positioned at two sides of the through hole in the first direction of the current collector;
the current collector comprises a first conductive layer, an insulating layer and a second conductive layer which are stacked;
the first functional surface is the surface of the first conductive layer far away from the insulating layer, and the second functional surface is the surface of the second conductive layer far away from the insulating layer;
in the first direction of the current collector, the ratio of the minimum distance W1 between the edges of the M through holes and the edges of the current collector to the dimension W0 of the first tab region and/or the second tab region is (0.2-0.8): m is less than or equal to 1 and N;
the first functional surface and/or the second functional surface are/is provided with protective layers, the protective layers cover the W through holes respectively, the protective layers are provided with openings at the corresponding positions of the W through holes, and W is less than or equal to N;
the area of the protective layer is 1.2-5 times of the area of the M through holes;
the ratio of the area of the through hole to the cross-sectional area of the second section is (1.2-50): 1.
2. the electrode tab of claim 1, wherein either end of the first segment or the second segment extends beyond the current collector.
3. The electrode sheet according to claim 1 or 2, wherein in the first direction of the current collector, the minimum distance between the edges of the M through holes and the edges of the current collector is W1, W1 is not less than 1mm; and/or the number of the groups of groups,
in the second direction of the current collector, the minimum distance between the edges of the M through holes and the edges of the first active layer area and/or the second active layer area is L1, and L1 is more than or equal to 2mm.
4. The electrode sheet according to any one of claims 1 to 2, wherein a minimum distance between an edge of a connection region and an edge of M of the through holes is not less than 1mm in a first direction of the current collector;
wherein the connection region comprises at least one of the first connection region, the second connection region, and the third connection region; and/or the number of the groups of groups,
in the first direction of the current collector, the minimum distance between the edge of the connecting area and the edge of the current collector is more than or equal to 1mm;
wherein the connection region includes at least one of the first connection region, the second connection region, and the third connection region.
5. The electrode tab of claim 3, wherein a minimum distance between an edge of the connection region and an edge of the M through holes is 1mm or more in the first direction of the current collector;
Wherein the connection region comprises at least one of the first connection region, the second connection region, and the third connection region; and/or the number of the groups of groups,
in the first direction of the current collector, the minimum distance between the edge of the connecting area and the edge of the current collector is more than or equal to 1mm;
wherein the connection region includes at least one of the first connection region, the second connection region, and the third connection region.
6. The electrode sheet of any one of claims 1-2, 5, wherein the protective layer has a thickness of 0.5-50 μm.
7. The electrode sheet according to claim 4, wherein the protective layer has a thickness of 0.5-50 μm.
8. An electrochemical device comprising the electrode sheet according to any one of claims 1 to 7.
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