CN117577776A - Electrode sheet, winding core and battery - Google Patents

Electrode sheet, winding core and battery Download PDF

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Publication number
CN117577776A
CN117577776A CN202311493931.5A CN202311493931A CN117577776A CN 117577776 A CN117577776 A CN 117577776A CN 202311493931 A CN202311493931 A CN 202311493931A CN 117577776 A CN117577776 A CN 117577776A
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CN
China
Prior art keywords
coating
coated
active material
whitening
electrode sheet
Prior art date
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Pending
Application number
CN202311493931.5A
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Chinese (zh)
Inventor
张健
何娜
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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Application filed by Zhuhai Cosmx Battery Co Ltd filed Critical Zhuhai Cosmx Battery Co Ltd
Publication of CN117577776A publication Critical patent/CN117577776A/en
Pending legal-status Critical Current

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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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention provides an electrode plate, a winding core and a battery. The electrode sheet is applied to a winding core, and comprises: a current collector including a first side and a second side disposed opposite each other; the protective coating comprises conductive powder, a conductive agent and an adhesive, and the protective coating comprises a target side face which is arranged away from the current collector; the active material coating includes an active material; in the case where the first side is not coated with the protective coating and the second side is coated with the protective coating, the active material coating is coated on the target side and the second side; in the case where both the first side and the second side are coated with the protective coating, the active material coating is coated on the target side; the whitening coating is coated on the side of the object, the area not coated with the active material coating is provided with the whitening coating, and the difference A between the grey values of the whitening coating and the ending glue of the winding core is 40 to 80. The invention solves the problems of difficult tail gum identification and easy air blowing at high temperature in the lithium ion battery.

Description

Electrode sheet, winding core and battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an electrode plate, a winding core and a battery.
Background
The lithium ion battery has the advantages of high platform voltage, high energy density, no memory effect, long service life and the like, and is widely applied to various electronic devices. In the case of the penetration of the lithium ion battery, the positive electrode, the negative electrode and the separator are in a partially broken state.
Under the condition that the active material coating of the positive plate drops due to puncture of the lithium ion battery, the aluminum foil can be directly exposed and contacted with the negative plate, so that the risk of thermal runaway of the lithium ion battery is increased. Therefore, the lithium ion battery in the prior art has lower safety under the condition of mechanical damage such as puncture.
Disclosure of Invention
The invention provides an electrode plate, a winding core and a battery, which are used for solving the problems that the tail rubber in a lithium ion battery is difficult to identify and the lithium ion battery is easy to blow air at high temperature.
In a first aspect, the present invention provides an electrode sheet for use in a jellyroll, comprising:
a current collector including a first side and a second side disposed opposite each other;
a protective coating comprising a target side disposed away from the current collector;
an active material coating layer comprising an active material;
wherein, in the case where the first side is not coated with the protective coating layer and the second side is coated with the protective coating layer, the active material coating layer is coated on the target side and the second side;
the active material coating is applied to the target side with the first side and the second side both coated with the protective coating;
a whitening coating applied to the target side, the areas not coated with active material coating being provided with a whitening coating, the difference a between the grey values of the whitening coating and the ending glue of the winding core being 40 to 80.
In one example, the difference B between the gray values of the protective coating and the ending glue of the winding core is 10 to 30, then a > B;
and/or the target side is provided with a first area and a second area, the second area is arranged close to the end part of the current collector, the active material coating is coated on the first area, and the whitening coating is coated on the second area.
In an example, the length of the second region ranges from 50mm to 200mm, and the length direction of the second region is parallel to the length direction of the current collector.
In one example, the whitening coating has a thickness of 2 μm to 20 μm, preferably 5 μm to 10 μm.
In one example, a is 50 to 80;
and/or B is 10 to 20;
and/or a-B is 30 to 70.
In one example, the whitening coating has a smaller coating area than the active material coating in the same target side;
and/or, the sum of the coating area of the whitening coating and the coating area of the active material coating is not smaller than the area of the target side of the protective coating.
In a second aspect, the invention also provides a winding core comprising an electrode sheet according to the first aspect.
In one example, in the electrode sheet, the second areas of the protective coating on both sides are coated with a whitening coating.
In one example, in the electrode sheet, a second region of the protective coating on one side is coated with a whitening coating, the whitening coating being located in a second region away from the center of the winding core.
In a third aspect, the invention also provides a battery comprising a winding core as described in the second aspect.
In the present invention, an electrode sheet, applied to a winding core, comprises: the current collector comprises a first side surface and a second side surface which are oppositely arranged; the protective coating is applied to the first side and/or the second side. Through the arrangement of the protective coating, one more layer of protection is provided for the current collector, the risk of exposing the current collector is reduced, the possibility of contacting with the negative electrode active layer is reduced, and the safety of the battery is improved. Meanwhile, the difference A between the gray values of the whitening coating and the ending glue of the winding core is limited to be 40-80 by arranging the whitening coating, so that the gray values of the whitening coating and the ending glue of the winding core are increased, the whitening coating and the ending glue can be distinguished more obviously and conveniently when the ending glue is positioned by using CCD equipment, the recognition degree is increased, and the accuracy and convenience of positioning the ending glue are improved; and the whitening coating is coated on the side surface of the target, and the whitening coating is arranged in the area which is not coated with the active material coating, so that the contact between the protective coating and the electrolyte is avoided, the side reaction between the protective coating and the electrolyte is reduced, the high-temperature air blowing is improved, and the expansion rate of the battery is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic cross-sectional view of an electrode sheet according to an embodiment of the present invention;
FIG. 2 is a second schematic cross-sectional view of an electrode sheet according to an embodiment of the present invention;
FIG. 3 is a third schematic cross-sectional view of an electrode sheet according to an embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view of an electrode sheet according to an embodiment of the present invention;
FIG. 5 is a schematic cross-sectional view of an electrode sheet according to an embodiment of the present invention;
FIG. 6 is a schematic cross-sectional view of an electrode sheet according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a winding core according to an embodiment of the present invention;
fig. 8 is a second schematic structural view of a winding core according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which are derived by a person skilled in the art from the embodiments according to the invention without creative efforts, fall within the protection scope of the invention.
Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. "upper", "lower", "left", "right", etc. are used merely to indicate a relative positional relationship, which changes accordingly when the absolute position of the object to be described changes. Herein, unless otherwise specified, data ranges all include endpoints.
As shown in fig. 1 to 6, the present invention provides an electrode sheet applied to a winding core, comprising:
a current collector 10, the current collector 10 including a first side and a second side disposed opposite to each other;
a protective coating 20 comprising a target side disposed away from the current collector 10;
an active material coating 30, the active material coating 30 including an active material;
wherein, in the case where the first side is not coated with the protective coating 20 and the second side is coated with the protective coating 20, the active material coating 30 is coated on the target side and the second side;
in the case where the first side and the second side are both coated with the protective coating 20, the active material coating 30 is coated on the target side;
a whitening coating 40, the whitening coating 40 being applied to the target side, the areas not coated with the active material coating being provided with a whitening coating, the difference a between the grey values of the whitening coating (40) and the ending glue of the winding core being 40 to 80 (e.g. 40, 45, 50, 55, 60, 65, 70, 75, 80).
Wherein the gray value can be obtained by a CCD visual detection system.
In one example, a is 50 to 80.
Referring to fig. 1, in one case, a protective coating 20 is applied to the first and second sides of the current collector 10, and the active material coating 30 is applied to the target side (the side of the protective coating 20 facing away from the current collector 10). Specifically, the target side of the protective coating 20 on both sides is coated with an active material coating 30.
Referring to fig. 2, in another case, the protective coating layer 20 is coated on only a first side of the current collector 10, and the active material coating layer 30 is coated on a target side of the protective coating layer 20 and a second side of the current collector 10.
It should be noted that, the first side and the second side are only used for separating two sides of the fluid 10 disposed opposite to each other, and the case that the protective coating 20 is only coated on the second side of the current collector 10 may be referred to the case that the protective coating 20 is only coated on the first side of the current collector 10, so that repetition is avoided, and detailed description is omitted herein.
It should be understood that the specific structure of the current collector 10 is not limited herein. Illustratively, in one embodiment, current collector 10 is aluminum foil.
It should be understood that the active material included in the active material coating 30 is not limited herein. In particular, the active material coating 30 may employ active materials commonly used in the related art. Illustratively, in one embodiment, the active material coating 30 includes lithium cobalt oxide, acetylene black, and polyvinylidene fluoride.
The protective coating 20 includes conductive powder, conductive agent and adhesive, wherein the specific proportions of the conductive powder, conductive agent and adhesive are not limited herein. The protective coating comprises conductive powder and conductive agent, so that the protective coating has good conductive performance, and the electrode plate has good electrical performance. Meanwhile, as the protective coating comprises the adhesive, the adhesive property between the protective coating and the current collector is improved, and the probability of falling off of the protective coating during mechanical abuse is reduced.
It should be understood that the specific structure of the conductive powder is not limited herein, and the conductive powder may be understood as a powder having conductivity. In this embodiment, the protective coating 20 uses conductive powder as a main material, so that the protective coating 20 has better conductivity, and further the lithium ion battery has better electrical performance.
Optionally, in an embodiment, the conductive powder includes inorganic particles and a conductive coating layer, and the conductive coating layer encapsulates the inorganic particles.
In one embodiment, the conductive powder is understood to be a composite conductive material with inorganic particles as a core and conductive coating as a shell.
Optionally, in an embodiment, the conductive coating layer is a metal oxide, or a metal oxide doped with an impurity element. The metal oxide may be any metal oxide, and the impurity element doped in the metal oxide may be any element. For example, in one embodiment, the conductive coating is tin oxide (SnO) doped with antimony (Sb) element 2 ) Or tin antimony oxide (Antimony Doped Tin Oxide, ATO). In another embodiment, the conductive coating is fluorine (F) -doped SnO 2 Or TCO conductive glass (FTO). The conductive coating layer is indium oxide (In) doped with tin (Sn) 2 O 3 ) Or Indium Tin Oxide (ITO).
Alternatively, in an embodiment, the conductive powder may include any inorganic particles. For example, in one embodiment, the conductive powder comprises inorganic particles comprising at least one of: titanium dioxide, zinc oxide, mica powder, quartz powder, barite, aluminum oxide, boehmite, magnesium oxide, and silicon oxide.
Alternatively, in an embodiment, the conductive powder has a Dv50 of less than 5 μm (e.g., 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, 0.5 μm, 0.1 μm). Still further, in an embodiment, the conductive powder has a Dv50 of less than 4 μm. Optionally, in another embodiment, the Dv50 of the conductive powder is less than 1 μm.
It is understood that Dv50 is understood to be the particle size corresponding to a cumulative volume particle size distribution percentage of a sample of 50%. Its physical meaning is that the particle size is greater than 50% of its particles and less than 50% of its particles, so Dv50 is also known as median or median particle size.
The Dv50 of the active material included in the active material coating 30 is typically 15 μm. In one embodiment, the Dv50 of the conductive powder is much less than the Dv50 of the active material included in the active material coating 30. As can be seen from the above, the D50 of the material included in the protective coating layer 20 is smaller, so that when the active material coating layer 30 breaks due to mechanical abuse, the probability of breaking the protective coating layer 20 is smaller, thereby reducing the probability of exposing the current collector 10 and improving the safety of the battery.
In one example, the difference B between the gray values of the protective coating 20 and the ending glue of the winding core is 10 to 30 (e.g., 10, 12, 15, 17, 20, 22, 25, 27, 30), then a > B.
In one example, B is 10 to 20.
In one example, a-B is 30 to 70 (e.g., 30, 35, 40, 45, 50, 55, 60, 65, 70).
The target side is provided with a first region and a second region, the second region is arranged near the end part of the current collector 10, in the winding core, the end part is the tail part far away from the center of the winding core, the active material coating 30 is coated on the first region, and the whitening coating 40 is coated on the second region.
In this embodiment, the electrode sheet further includes a whitening coating 40, and illustratively, in one embodiment, the whitening coating 40 includes inorganic particles. Still further, in another embodiment, the whitening coating 40 includes inorganic particles comprising at least one of: alumina, boehmite, magnesia, titania, zinc oxide and silica.
Referring to fig. 3, in one case, a protective coating 20 is coated on the first and second sides of the current collector 10, and the whitening coating 40 and the active material coating 30 are coated on the target sides. Specifically, the first areas of the protective coating 20 on both sides are coated with the active material coating 30 and the second areas of the protective coating 20 on both sides are coated with the whitening coating 40. At this time, the protective coating is covered by the whitening coating and the active material coating, so that the protective coating and the electrolyte are not in direct contact, the problem of gas production caused by side reaction when the protective coating is in contact with the electrolyte is solved, and the expansion rate of the battery is further reduced.
Of course, as shown in fig. 4, in an embodiment, only the second region of the protective coating 20 on one side may be coated with the whitening coating 40.
In the embodiment shown in fig. 4, only the second areas of the protective coating 20 on one side of the two-sided protective coating 20 are coated with a whitening coating 40, the whitening coating 40 being located in the second areas away from the center of the winding core. At this time, the whitening coating may reduce the risk of short circuit in case of mechanical damage such as puncture of the battery, for example, the positive electrode current collector is in contact with the negative electrode active material coating, or the negative electrode current collector is in contact with the positive electrode active material coating, so that the safety performance of the battery may be improved.
In another embodiment, as shown in fig. 5, the protective coating 20, which is not coated with the whitening coating 40, does not completely cover the current collector 10. As shown in fig. 7, when the winding core is wound, the area of the current collector 10 not covered by the protective coating 20 faces the inside of the winding core, and is hard to short-circuit with the nail at the time of piercing, and the contact with the current collector is also a positive plate, so that the probability of short-circuit with the negative electrode is low, and the safety risk is low.
Referring to fig. 6, in another case, the protective coating 20 is coated on only the first side of the current collector 10, and the active material coating 30 and the whitening coating 40 are coated on the target side. Specifically, a first region of the protective coating 20 is coated with the active material coating 30 and a second region of the protective coating 20 is coated with the whitening coating 40, the whitening coating 40 being located in a second region remote from the core center.
It should be noted that the electrode sheet schematic diagrams shown in fig. 1 to 6 are only for illustrating the relative positions among the current collector 10, the protective coating layer 20, the active material coating layer 30, and the whitening coating layer 40, and the widths and lengths of the above respective coating layers are only for illustration, and do not indicate information or correspondence of the lengths or widths of the current collector 10, the protective coating layer 20, the active material coating layer 30, and the whitening coating layer 40.
It should be noted that, the specific process of preparing the winding core based on the electrode sheet provided by the invention can be referred to the description in the related art, and in order to avoid repetition, the description is omitted here. For ease of understanding, only the ending glue will be briefly described below.
In the process of preparing a winding core based on an electrode sheet, it is necessary to wind the electrode sheet and bond a finishing glue at the finishing of the winding core formed after winding. Therefore, the ending glue is positioned at the end part of the winding core and is adhered and fixed with the surface of the outermost ring of the winding core, which is far away from the center of the winding core.
In one embodiment, the second region is disposed near the end of the current collector 10, and the whitening coating 40 is coated on the second region, so it can be understood that the surface of the outermost turn of the winding core, which is far from the center of the winding core, is provided with the whitening coating 40, and the whitening coating 40 is located at the end of the winding core. When the ending glue is adhered to the ending of the winding core, the ending glue 50 will be connected to the whitening coating 40 and cover part of the whitening coating 40, see fig. 8.
In particular implementations, the protective coating 20 includes conductive powder, conductive agent, and adhesive, and the difference between the gray values of the protective coating 20 and the ending glue is generally small, so it is difficult to distinguish the protective coating 20 and the ending glue when the ending glue is positioned using a charge coupled device (Charge Coupled Device, CCD) apparatus.
By arranging the whitening coating 40 in the invention, the gray value of the ending glue of the whitening coating 40 and the winding core is increased, and the whitening coating 40 and the ending glue can be distinguished more obviously and conveniently when the ending glue is positioned by using CCD equipment, thereby improving the accuracy and convenience of positioning the ending glue. Meanwhile, the whitening coating 40 does not cover the active material coating 30, so that interference of the whitening coating 40 to the active material coating 30 is reduced, and performance (for example, energy density) of the electrode sheet is not affected.
Optionally, in an embodiment, the length of the second region ranges from 50mm to 200mm (e.g., 50mm, 70mm, 100mm, 120mm, 150mm, 170mm, 200 mm), and the length direction of the second region is parallel to the length direction of the current collector 10.
It should be appreciated that the length direction of the second region is parallel to the length direction of the current collector 10. For example, as illustrated in the rectangular coordinate system of fig. 1, the length direction of the second region is the direction of the x-axis illustrated in fig. 1.
It should be understood that the length direction of the current collector 10 is understood to be the length direction of the current collector 10 in a flat state before the electrode sheet is not wound.
In one embodiment, the length of the second region ranges from 50mm to 200mm. Since the length of the second region ranges from 50mm to 200mm, the area of the whitening coating 40 is much smaller than the area of the active material coating 30 (i.e., the coating area of the whitening coating is smaller than the coating area of the active material coating in the same target side), so that the influence of the arrangement of the whitening coating 40 on the function of the active material coating 30 can be reduced, the performance of the electrode sheet (e.g., the energy density of the battery) is not affected, and the battery has a higher energy density under the condition of ensuring the safety performance of the battery.
Optionally, in an embodiment, the sum of the coated area of the whitening coating and the coated area of the active material coating is greater than the area of the target side of the protective coating. At the moment, the protective coating can be prevented from being in direct contact with the electrolyte, and the risk of gas production is reduced, so that the high-temperature expansion rate of the battery is reduced.
Alternatively, in one embodiment, the resistivity of the conductive powder ranges from 0.01Ω·m to 10Ω·m (e.g., 0.01Ω·m, 0.05 Ω·m, 0.1 Ω·m, 0.15 Ω·m, 0.2 Ω·m, 0.25 Ω·m, 0.3 Ω·m, 0.35 Ω·m, 0.4 Ω·m, 0.45 Ω·m, 0.5 Ω·m, 0.55 Ω·m, 0.6Ω·m, 0.65Ω·m, 0.7Ω·m, 0.75Ω·m, 0.8Ω·m, 0.85Ω·m, 0.9Ω·m, 1 Ω·m, 2 Ω·m, 3 Ω·m, 4 Ω·m, 5 Ω·m, 7Ω·m, 8Ω·m, 9Ω·m, 10Ω·m). Alternatively, in another embodiment, the resistivity of the conductive powder ranges from 0.1 Ω·cm to 1 Ω·m.
In one embodiment, the resistivity of the conductive powder ranges from 0.01Ω·m to 10Ω·m, or preferably, the resistivity of the conductive powder ranges from 0.1Ω·cm to 1Ω·m. By the arrangement, the protective coating 20 has better electric conductivity, and further the lithium ion battery has better electric performance.
It should be understood that the specific materials of the conductive agent are not limited herein. For example, in one embodiment, the conductive agent includes at least one of: conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes, and carbon nanofibers.
It should be understood that the specific materials of the binder are not limited herein. For example, in one embodiment, the binder comprises at least one of: polyvinylidene fluoride (polyvinylidene difluoride, PVDF), acrylic-modified PVDF, polyacrylate polymers, polyimide, styrene-butadiene rubber, and styrene-acrylic rubber.
Optionally, in one embodiment, the proportion of binder within the protective coating 20 is greater than the proportion of binder included in the active material coating 30, thereby further increasing the adhesion between the protective coating 20 and the current collector 10 and reducing the risk of the protective coating 20 falling out when subjected to external forces.
In one embodiment, an electrode sheet, applied to a winding core, comprises: current collector 10, protective coating 20, and active material coating 30, current collector 10 comprising a first side and a second side disposed opposite each other; the protective coating 20 is coated on the first side and/or the second side, and the protective coating 20 includes conductive powder, a conductive agent, and an adhesive. By providing the protective coating 20, a further layer of protection is provided to the current collector 10, reducing the risk of exposure of the current collector 10. Since the protective coating 20 comprises conductive powder and conductive agent, the protective coating 20 has better conductive performance, and the electrode plate has better electrical performance. Meanwhile, since the protective coating 20 includes an adhesive, the adhesion property between the protective coating 20 and the current collector 10 is improved, and the probability of the protective coating 20 falling off upon mechanical abuse is reduced.
The invention also provides a winding core which comprises the electrode plate. In an embodiment, the electrode sheet is an electrode sheet in the above embodiment, and the specific structure may refer to the description in the above embodiment, which is not repeated herein. The electrode sheet in the embodiment is adopted in the invention, so the winding core provided by the invention has all the beneficial effects of the electrode sheet in the embodiment.
In the case of mechanical abuse, the risk of thermal runaway due to contact between the current collector 10 of the positive electrode sheet and the negative electrode sheet is high. Thus, in one embodiment, the electrode sheet described above is used as the positive electrode sheet. Specifically, in an embodiment, the winding core includes the electrode sheet, the separator, and the negative electrode sheet in the above embodiments. The electrode sheet, the separator and the negative electrode sheet in the above embodiment are sequentially stacked and wound to form a winding core. In this embodiment, the protective coating 20 is disposed on the current collector 10 of the positive plate, so that the current collector 10 of the positive plate and the negative plate are prevented from being shorted when the battery is abused mechanically, and the safety of the battery is improved.
In one example, in the electrode sheet, the second areas of the protective coating 20 on both sides are coated with a whitening coating 40.
In one example, in the electrode sheet, a second region of the protective coating 20 on one side is coated with a whitening coating 40, the whitening coating 40 being located in a second region away from the center of the winding core.
The invention also provides a battery, which comprises the winding core. It should be noted that, the battery provided by the present invention includes all the technical features in the embodiment of the winding core, and can achieve the same technical effects, so that repetition is avoided, and no further description is provided herein.
The battery provided by the invention can be applied to electronic equipment or used as a power battery to provide power for power vehicles such as electric automobiles, electric trains, electric bicycles, golf carts and the like.
The electronic Device may be a mobile phone, a tablet (Tablet Personal Computer), a Laptop (Laptop Computer) or a terminal-side Device called a notebook, a personal digital assistant (Personal Digital Assistant, PDA), a palm top, a netbook, an ultra-mobile personal Computer (ultra-mobile personal Computer, UMPC), a mobile internet Device (Mobile Internet Device, MID), a Wearable Device (wireless Device) or a vehicle-mounted Device (Vehicle User Equipment, VUE), a pedestrian terminal (Pedestrian User Equipment, PUE), and the Wearable Device includes: smart watches, bracelets, headphones, eyeglasses, etc. It should be noted that, the embodiments of the present application are not limited to the specific types of the electronic devices described above.
In order to facilitate understanding, the structure, the preparation process and the effects of the electrode sheet, the winding core and the battery provided by the embodiment of the invention will be described below by taking specific examples as examples. First, the preparation process of the electrode sheet, the winding core and the battery is described.
Example 1
A protective coating 20 slurry is prepared. Specifically, 90% by mass of conductive titanium dioxide (ATO-coated TiO) 2 ) 2% by mass of carbon black, 1% by mass of carbon nano-meter and 7% by mass of PVDF were mixed, a certain amount of N-Methylpyrrolidone (NMP) was added, the solid content of the slurry was adjusted to 40%, and a protective coating 20 slurry was prepared by stirring.
A slurry of the whitening coating 40 is prepared. Specifically, 90% by mass of boehmite and 10% by mass of PVDF were mixed, a certain amount of NMP was added, the solid content of the slurry was adjusted to 40%, and the slurry was prepared into a whitening coating 40 slurry by stirring.
An active material coating 30 slurry of the positive electrode sheet was prepared. The active material coating 30 of the positive electrode sheet may be formulated in the related art. Specifically, in this example, 96% by mass of lithium cobaltate, 1% by mass of carbon black+1% by mass of carbon nanotubes, and 2% by mass of PVDF were mixed, a certain amount of NMP was added, the solid content of the slurry was adjusted to 70%, and the slurry was stirred to prepare an active material coating 30 slurry for a positive electrode sheet.
An active material coating 30 slurry of the negative electrode sheet was prepared. The active material coating 30 of the negative electrode sheet may be formulated in the related art. Specifically, in this example, 96% by mass of artificial graphite, 1% by mass of carbon black, 1.5% by mass of styrene-butadiene rubber, and 1.5% by mass of sodium carboxymethyl cellulose were mixed, deionized water was added to adjust the solid content of the slurry to 40%, and the slurry was stirred to prepare an active material coating 30 slurry for a negative electrode sheet.
And (5) preparing a positive plate. Specifically, the prepared slurry of the protective coating 20 is coated on two opposite sides of the positive electrode current collector 10, the prepared slurry of the whitening coating 40 is coated on a second area of the protective coating 20, then the slurry of the active material coating 30 of the positive electrode sheet is coated on the second area of the protective coating 20, and the positive electrode sheet is obtained after drying. See in particular table 1.
And preparing a negative electrode sheet. Specifically, the active material coating 30 slurry of the prepared negative electrode sheet is coated on the negative electrode current collector 10 through an extrusion coating process to obtain the negative electrode sheet.
And respectively rolling the positive and negative pole pieces to the designed thickness by using a roller press, slitting the positive and negative pole pieces to the designed width by using a slitting machine, welding the lugs on the pole pieces, and attaching protective gummed paper.
And (3) placing the diaphragm between the positive plate and the negative plate for winding or laminating to obtain a winding core or a lamination core, and attaching gummed paper for fixation.
And (3) punching the aluminum-plastic film by using a punching die, packaging the rolled core or the stacked core by using the punched aluminum-plastic film to obtain the battery core, baking until the moisture is qualified, and injecting electrolyte.
And (3) charging and discharging the battery cell by using lithium ion battery formation equipment, hardening the battery cell, and sorting the capacity of the battery cell.
And (5) performing secondary sealing on the battery cell, and performing edge folding to basically mold the battery cell.
Example 2 group
Example 2a
Reference is made to example 1 except that the second region of the protective coating on one side is coated with a whitening coating and the whitening coating is located in a second region remote from the centre of the winding core, see in particular table 1.
Example 2b
Reference is made to example 1 except that the second region of the protective coating on one side is coated with a whitening coating and the whitening coating is located in the second region near the center of the winding core, see in particular table 1.
Example 3 group
This set of examples is intended to illustrate the effect that occurs when A-B changes.
This example set was performed with reference to example 1, except that a-B was changed by adjusting a and/or B, see in particular table 1.
Example 4 group
This set of examples is intended to illustrate the effect that occurs when the thickness of the whitening coating is changed.
This example set was performed with reference to example 1, except that the thickness of the whitening coating was varied, see in particular table 1.
Example 5
This example was conducted with reference to example 1, except that the sum of the coated area of the whitening coating and the coated area of the active material coating was less than the area of the target side of the protective coating, see in particular table 1.
Example 6
This example was conducted with reference to example 1, except that the coated area of the whitening coating and the coated area of the active material coating were changed, wherein the sum of the coated area of the whitening coating and the coated area of the active material coating was equal to the area of the target side of the protective coating, see in particular table 1.
Comparative example 1
With reference to example 1, except that both opposite sides of the current collector 10 of the positive electrode sheet were not coated with the protective coating 20, i.e., the battery in comparative example 1 did not include the protective coating 20.
Comparative example 2
Reference is made to example 1, except that the positive electrode sheet does not protect the whitening coating.
Comparative example 3
Reference example 1 was performed except that a was 20 and B was 20, i.e., a=b.
TABLE 1
* The same as in example 1;
-indicating absence.
Test case
In order to test the performance of the battery prepared in the examples and the performance of the battery prepared in the comparative examples, the battery prepared in the examples and the battery prepared in the comparative examples were respectively subjected to an open circuit voltage (Open Circuit Voltage, OCV) test, the K value of the battery was tested, and a product having a qualified K value was selected.
(1) Needling test
The batteries prepared in examples and the batteries prepared in comparative examples were subjected to needling test, respectively. Specifically, the lithium ion battery is fully charged (100% SOC), then the lithium ion battery is placed on a test bench of a needling test device, a tungsten steel needle with the diameter of 3mm and the needle tip length of 3.62mm is used for piercing the middle of the battery at the speed of 100mm/s, the battery is not fired and is not exploded to pass the test, the needling passing condition a/b is used for representing that in any b needling tests, and the number of times of the test result is a.
(2) Recognition rate test
And (3) manufacturing a certain quantity of batteries in batches, for example, checking and judging whether the rubberizing position of the final gummed paper is qualified or not through a CCD visual inspection system and a manual total inspection on the batteries with the quantity of M, wherein the quantity of unqualified products judged by the CCD visual inspection system is A through the manual total inspection, the quantity of unqualified products judged by the CCD visual inspection system is B through the manual total inspection, and the recognition rate is [1- (A+B)/M ] 100%.
(3) Energy density testing
The battery is discharged to the lowest voltage (generally 3.0V) after being fully charged, the discharge energy is recorded as E, the energy density is E/(L.W.H), L is the length of the battery, W is the width of the battery, and H is the height of the battery.
(4) Expansion ratio test
The battery is stored for 30D under the high-temperature environment of 60 ℃, the initial thickness is recorded as D1, the thickness after storage is recorded as D2, and the expansion ratio is [ (D2-D1)/D1 ]. Times.100%.
The results of performance tests on the batteries prepared in examples and the batteries prepared in comparative examples are shown in table 2.
TABLE 2
The foregoing is merely illustrative embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think about variations or substitutions within the technical scope of the present invention, and the invention should be covered. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (10)

1. An electrode sheet for a jellyroll, comprising:
a current collector (10), the current collector (10) comprising a first side and a second side disposed opposite each other;
-a protective coating (20) comprising a target side, the target side being disposed away from the current collector (10);
an active material coating (30), the active material coating (30) comprising an active material;
wherein the active material coating (30) is applied to the target side and the second side with the first side not being coated with the protective coating (20) and the second side being coated with the protective coating (20);
the active material coating (30) is applied to the target side with the first side and the second side both coated with the protective coating (20);
a whitening coating (40), the whitening coating (40) being applied to the target side, the areas not being coated with an active material coating being provided with a whitening coating, the difference a between the grey values of the whitening coating (40) and the ending glue of the winding core being 40 to 80.
2. Electrode sheet according to claim 1, characterized in that the difference B between the gray values of the protective coating (20) and the ending glue of the winding core is 10 to 30, a > B;
and/or the target side is provided with a first area and a second area, the second area is arranged near the end part of the current collector (10), the active material coating (30) is coated on the first area, and the whitening coating (40) is coated on the second area.
3. Electrode sheet according to claim 2, characterized in that the length of the second region is in the range of 50-200 mm, the length direction of the second region being parallel to the length direction of the current collector (10).
4. Electrode sheet according to claim 1, characterized in that the thickness of the whitening coating is 2 μm to 20 μm, preferably 5 μm to 10 μm.
5. The electrode sheet of claim 1, wherein a is 50 to 80;
and/or B is 10 to 20;
and/or a-B is 30 to 70.
6. The electrode sheet according to any one of claims 1 to 5, wherein a coating area of the whitening coating is smaller than a coating area of the active material coating in the same target side;
and/or, the sum of the coating area of the whitening coating and the coating area of the active material coating is greater than or equal to the area of the target side of the protective coating.
7. A winding core comprising an electrode sheet according to any one of claims 1-6.
8. A winding core according to claim 7, characterized in that in the electrode sheet, the second areas of the protective coating (20) on both sides are coated with a whitening coating (40).
9. A winding core according to claim 7, characterized in that in the electrode sheet a second area of the protective coating (20) on one side is coated with a whitening coating (40), the whitening coating (40) being located in a second area remote from the centre of the winding core.
10. A battery comprising a winding core according to any one of claims 7-9.
CN202311493931.5A 2022-11-09 2023-11-09 Electrode sheet, winding core and battery Pending CN117577776A (en)

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JP2011076740A (en) * 2009-09-29 2011-04-14 Panasonic Corp Wound electrode group and battery using the same, and manufacturing method of battery
CN202363549U (en) * 2011-12-15 2012-08-01 协鑫动力新材料（盐城）有限公司 Winding-type lithium ion battery structure
CN108615924B (en) * 2015-12-14 2021-04-27 东莞新能源科技有限公司 Battery cell and lithium ion battery adopting battery cell
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