CN113066986A - Current collector, preparation method thereof and pole piece - Google Patents

Current collector, preparation method thereof and pole piece Download PDF

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Publication number
CN113066986A
CN113066986A CN202110279021.1A CN202110279021A CN113066986A CN 113066986 A CN113066986 A CN 113066986A CN 202110279021 A CN202110279021 A CN 202110279021A CN 113066986 A CN113066986 A CN 113066986A
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China
Prior art keywords
metal layer
thinned
current collector
thickness
layer
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CN202110279021.1A
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Chinese (zh)
Inventor
赵伟
唐伟超
李素丽
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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Priority to CN202110279021.1A priority Critical patent/CN113066986A/en
Publication of CN113066986A publication Critical patent/CN113066986A/en
Priority to PCT/CN2022/081275 priority patent/WO2022194222A1/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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/661—Metal or alloys, e.g. alloy 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Cell Electrode Carriers And Collectors (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

The invention provides a current collector, a preparation method thereof and a pole piece, wherein the current collector comprises a first metal layer and a second metal layer compounded with the first metal layer, the first metal layer is provided with a first part and a second part, the second metal layer is provided with a third part and a fourth part layer, the first part and the third part are connected through a gluing layer, and the second part and the fourth part are connected through welding. The invention can effectively improve the safety of the battery, enables the battery to have lower internal resistance, and can improve the welding processing performance of the current collector in the subsequent battery manufacturing process, mainly shows that the conventional welding process of the pure metal current collector can be adopted, and higher welding strength can be obtained without special welding process or welding structure design.

Description

Current collector, preparation method thereof and pole piece
Technical Field
The invention belongs to the field of batteries, and particularly relates to a current collector, a preparation method thereof and a pole piece adopting the current collector.
Background
The lithium ion battery has high energy density and high power density, is a secondary battery with wide application, and has wide application prospect in the fields of consumer electronics, electric vehicles, energy storage and the like. However, the safety of the conventional lithium ion battery needs to be further improved, for example, under some abuse conditions (such as needling, extrusion, impact, etc.), the internal short circuit of the battery is often caused, and thermal runaway is caused to cause safety accidents, so that the attention on improving the safety performance of the battery is getting higher, and it is an important issue for those skilled in the art to improve the safety of the battery while ensuring that the battery has characteristics such as lower internal resistance.
Disclosure of Invention
The invention provides a current collector, a preparation method thereof and a pole piece adopting the current collector, which can effectively improve the safety of a battery and enable the battery to have lower internal resistance.
In one aspect of the invention, a current collector is provided, which includes a first metal layer and a second metal layer compounded with the first metal layer, the first metal layer has a first portion and a second portion, the second metal layer has a third portion and a fourth portion, the first portion and the third portion are connected through a glue coating layer, and the second portion and the fourth portion are connected through welding.
According to an embodiment of the invention, the surface area of the first portion is 50-98% of the surface area of the first metal layer and the surface area of the third portion is 50-98% of the surface area of the second metal layer.
According to an embodiment of the invention, the first portion comprises a first thinning, the thickness of the first thinning being smaller than the thickness of the second portion; and/or the third portion comprises a second thinned portion having a thickness less than the thickness of the fourth portion.
According to an embodiment of the present invention, the first thinning section is formed by etching and thinning the first metal layer, and/or the second thinning section is formed by etching and thinning the second metal layer.
According to one embodiment of the invention, when the etching thinning treatment is performed, a first non-thinned region including the second portion on the first metal layer is provided with a protective layer, and the protective layer is used for preventing the first non-thinned region from being etched and thinned; and/or when the corrosion thinning treatment is carried out, a second non-thinned region including the fourth part on the second metal layer is provided with a protective layer, and the protective layer is used for preventing the second non-thinned region from being corroded and thinned.
According to an embodiment of the invention, the first portion comprises a first thinned portion remote from the second portion and a first non-thinned portion close to the second portion, the first non-thinned portion having a length d in a direction along the first thinned portion to the first non-thinned portion1，0.3mm≤d1The thickness of the second part and the thickness of the first non-thinned part are greater than the thickness of the first thinned part; and/or the third portion comprises a second thinned portion distal from the fourth portion and a second non-thinned portion proximal to the fourth portion, the second non-thinned portion having a length d in a direction along the second thinned portion to the second non-thinned portion2，0.3mm≤d2The thickness of the fourth part and the thickness of the second non-thinned part are larger than the thickness of the second thinned part.
According to an embodiment of the present invention, the first and second thinned portions have a thickness of 0.1 to 5 μm, respectively, and the second, first, fourth and second non-thinned portions have a thickness of 1 to 20 μm, respectively.
According to an embodiment of the present invention, the thickness of the glue coating layer is 0.5 to 5 μm.
In another aspect of the present invention, a method for preparing the current collector is provided, including: applying a glue to one surface of at least one of the first portion of the first metal layer and the third portion of the second metal layer; compounding the first metal layer and the second metal layer to ensure that the first part is connected with the third part through a glue coating layer formed by gluing; and welding the second part of the first metal layer and the fourth part of the second metal layer together to obtain the current collector.
In another aspect of the present invention, a pole piece is provided, which includes the current collector and an active material layer on at least one surface of the current collector; and the pole lug is welded on a welding part formed by the first part of the first metal layer and the third part of the second metal layer of the current collector.
Through the structural design, the current collector has obvious safety compared with the traditional pure metal foil type current collector, and has lower internal resistance compared with the current collectors of the conventional polymer layer-metal foil layer or other sandwich type structures, so that the current collector can effectively improve the quality of the battery such as safety, stability, cyclicity and the like, and is beneficial to practical industrial application. In addition, compared with the current collector with a conventional polymer layer-metal foil layer or other sandwich-type structures, the welding processing performance of the current collector in the subsequent battery manufacturing process can be improved, the current collector mainly shows that the conventional welding process of a pure metal current collector can be used, and higher welding strength can be obtained without special welding process or welding structure design.
Drawings
Fig. 1 is a schematic structural view of a current collector according to an embodiment of the present invention;
fig. 2 is a schematic structural view of a current collector according to another embodiment of the present invention;
fig. 3 is a schematic structural view of a current collector according to still another embodiment of the present invention;
fig. 4 is a schematic structural view of a current collector according to still another embodiment of the present invention;
fig. 5 is a schematic structural diagram of a comparative metal layer-polymer layer-metal layer three-layer composite current collector.
Description of reference numerals:
1: gluing layers; 1': a polymer layer; 11: a first glue layer; 12: a second glue coating layer; 21. 21': a first metal layer; 22. 22': a second metal layer; 211: a first portion; 212: a second portion; 221: a third portion; 222: a fourth part; 2111: a first thinning portion; 2112: a first unreduced portion; 2211: second thinning portion, 2212: a second unreduced portion.
Detailed Description
In order that those skilled in the art will better understand the concept of the present invention, the following detailed description is given with reference to the accompanying drawings.
As shown in fig. 1 to 4, the current collector of the present invention comprises a first metal layer 21 and a second metal layer 22 compounded with the first metal layer 21, the first metal layer 21 has a first portion 211 and a second portion 212, the second metal layer 22 has a third portion 221 and a fourth portion 222, the first portion 211 and the third portion 221 are connected by an adhesive coating 1, and the second portion 212 and the fourth portion 222 are connected by welding.
Generally, a projection of the first metal layer 21 parallel to a plane of the current collector surface and a projection of the second metal layer 22 parallel to a plane of the current collector surface are mutually covered (i.e., an edge of the first metal layer 21 is aligned with an edge of the second metal layer 22), the current collector surface is an upper surface or a lower surface of the current collector, and a direction from the upper surface to the lower surface is parallel to a direction from the first metal layer 21 to the second metal layer 22, i.e., a thickness direction of the current collector.
In some embodiments, the area of the first portion 21 is 50-98% of the area of the first metal layer 21, and the surface area of the third portion 221 is 50-98% of the surface area of the second metal layer 22, i.e., one side of the first metal layer 21 is connected to one side of the second metal layer 22 in a manner that: and 50 to 98 percent of the area (the first part/the third part) is connected through the glue coating layer 1, and the rest area (the second part/the fourth part) is connected through welding of the glue coating layer and the glue coating layer, so that the safety of the current collector is further improved, and the internal resistance is reduced.
Further considering the effect of improving the safety and internal resistance of the current collector, in some embodiments, the thickness of the second portion 212 is not less than the thickness of the first portion 211, and/or the thickness of the fourth portion 222 is not less than the thickness of the third portion 221.
Specifically, in some embodiments, as shown in fig. 1 and 3, the thickness of the first portion 211 is equal to the thickness of the second portion 212, the thickness of the third portion 221 is equal to the thickness of the fourth portion 222, and the thickness of the first portion 211 and the thickness of the third portion 221 may be 1-20 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or a range consisting of any two of these values, respectively.
In other embodiments, the first portion 211 includes a first thinned portion 2111, the first thinned portion 2111 has a thickness less than that of the second portion 212, the third portion 221 includes a second thinned portion 2211, the second thinned portion 2211 has a thickness less than that of the fourth portion 222, the first and second thinned portions 2111, 2211 may each have a thickness of 0.1-5 μm, such as 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or a range of any two of these values, the second portion 212 and the fourth portion 222 may each have a thickness of 1-20 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 9 μm, 12 μm, 13 μm, and 3 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or a range consisting of any two of these values.
In some embodiments, the first thinning portion 2111 may be formed by etching and thinning the first metal layer 21; the second thinning portion 2211 may be formed by performing an etching thinning process on the second metal layer 22. Optionally, the etching thinning treatment is, for example, etching with a metal etching solution or electrochemical etching or a combination of the two.
Specifically, in some embodiments, when performing the etching thinning process, a first non-thinned region including the second portion 212 on the first metal layer 21 is provided with a protective layer, which is used to prevent the first non-thinned region from being etched and thinned, so as to implement the thinning process of a preset first thinned region, and form a first thinned portion; when the etching thinning process is performed, a second non-thinned region including the fourth portion 222 on the second metal layer 22 is provided with a protection layer, and the protection layer is used for etching thinning of the second non-thinned region, so that the predetermined thinning process of the second thinned region is realized, and a second thinned portion is formed. And after the thinning treatment is finished, removing the protective layers arranged in the first non-thinning region and the second non-thinning region.
Alternatively, the first thinned portion 2111 may be a partial region of the first portion 211 (i.e., the first portion includes the first thinned portion and a first non-thinned portion having a thickness greater than the first thinned portion, the first non-thinned region includes the first non-thinned portion and the second portion), or may be an entire region of the first portion 211 (i.e., the first portion is entirely the first thinned portion, the first non-thinned region includes the second portion); the second thinning portion 2211 may be a partial area of the third portion 221 (i.e., the third portion includes the second thinning portion and a second non-thinning portion having a thickness greater than that of the second thinning portion, and the second non-thinning area includes the second non-thinning portion and the fourth portion), or may be an entire area of the third portion 221 (i.e., the third portion is entirely the second thinning portion, and the second non-thinning area includes the fourth portion).
To further ensure the strength of the junction between the first portion 211 and the second portion 212, and the strength of the junction between the third portion 221 and the fourth portion 222, and improve the safety of the current collector, in some embodiments, as shown in fig. 2 and 4, the first portion 211 includes a first thinned portion 2111 far away from the second portion 212 and a first non-thinned portion 2112 close to the second portion 212, and the first non-thinned portion 2112 has a length d in a direction from the first thinned portion 2111 to the first non-thinned portion 21121，0.3mm≤d1≤3mm，d1For example, 0.3mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm or a range consisting of any two of these values, the thickness of the second portion 212, the thickness of the first unreduced portion 2112, or both is greater than the thickness of the first reduced portion 2111; and/or, the third portion 221 includes a second thinned portion 2211 distant from the fourth portion 222 and a second non-thinned portion 2212 close to the fourth portion 222, the second non-thinned portion 2212 has a length d in a direction along the second thinned portion 2211 to the second non-thinned portion 2212 (the same direction as the first thinned portion 2111 to the first non-thinned portion 2112)2，0.3mm≤d2≤3mm，d2E.g., 0.3mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm or a range consisting of any two of these values, the thickness of the fourth portion 222, the thickness of the second unreduced portion 2212The thickness is greater than that of the second reduced thickness portion 2211. By the arrangement of the first non-thinned portion 2112 and the second non-thinned portion 2212, the mechanical strength of the joint of the metal layer (the first metal layer 21/the second metal layer 22) bonded by the glue layer (the first portion 211/the third portion 221) and the welded portion (the second portion 212/the fourth portion 222) can be improved, and the safety and other characteristics of the current collector can be further improved.
Specifically, the thicknesses of the first thinned portion 2111 and the second thinned portion 2211 may be 0.1 to 5 μm, such as 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or a range composed of any two of these values, respectively, and the thicknesses of the second portion 212, the first unreduced portion 2112, the fourth portion 222, and the second unreduced portion 2212 may be 1 to 20 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or a range composed of any two of these values. Wherein the thickness of the second portion 212 and the first non-thinned portion 2112 may be equal, and the thickness of the fourth portion 222 and the second non-thinned portion 2212 may be equal.
In some embodiments, the thickness of the glue coating layer 1 may be 0.5-5 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4m, 4.5 μm, 5 μm, or a range composed of any two of these values, which is beneficial to further improve the safety of the current collector and reduce the internal resistance thereof. The coating 1 may be integrally formed, for example, a coating is formed on the first portion 211 of the first metal layer 21 or the third portion 221 of the second metal layer 22, and then the first metal layer 21 and the second metal layer 22 are composited (as shown in fig. 1 and fig. 2), or the coating 1 may also include a first coating 11 and a second coating 12, for example, a first coating 11 is formed on the first portion 211 of the first metal layer 21, a second coating 12 is formed on the third portion 221 of the second metal layer 22, and then the first metal layer 21 and the second metal layer 22 are composited, and the first coating 11 and the second coating 12 are mutually attached, so that a projection of the first coating 11 parallel to a plane where the current collector surface is located covers a projection of the second coating 12 parallel to a plane where the current collector surface is located (shapes of the first coating 11 and the second coating 12, a projection of the first coating 11 parallel to a plane where the current collector surface is located, The same parameters such as the size of the area), that is, the same parameters such as the shape, the size of the area, etc. of the first glue layer 11 and the second glue layer 12, and the positions thereof are corresponding to each other (as shown in fig. 3 and fig. 4), the thicknesses of the first glue layer 11 and the second glue layer 12 may be equal or unequal, as long as the total thickness of the glue layers 1 is within the above range.
The raw material of the adhesive layer 1 may be a conventional material in the art, such as a polymer with an adhesive effect, and in some preferred embodiments, the raw material of the adhesive layer may include at least one of a polyurethane-type adhesive, an acrylic resin-type adhesive, a urea-formaldehyde resin-type adhesive, an epoxy resin-type adhesive, a silica-gel-type adhesive, a polysulfide-type adhesive, an amino resin-type adhesive, a phenol-formaldehyde resin-type adhesive, a furan resin-type adhesive, a polyvinyl acetal adhesive, a chloroprene rubber-type adhesive, a polyimide-type adhesive, an unsaturated polyester-type adhesive, and a composite resin adhesive, and the raw material is used to form the adhesive layer 1, which is beneficial to enhancing the bonding degree of the first metal layer 21 and the second metal layer 22, and further improving the characteristics of the current collector.
Specifically, as shown in fig. 1 to 4, the first portion 211 is located at one end of the first metal layer 21, the second portion 212 is located at the other end of the first metal layer 21, the third portion 221 is located at one end of the second metal layer 22, and the fourth portion 222 is located at the other end of the second metal layer 22.
Generally, the pole piece is provided with a tab, and the tab is arranged at one end of the pole piece, when the current collector disclosed by the invention is applied, the tab can be welded at a welding part formed by the first part 211 of the first metal layer 21 and the third part 221 of the second metal layer 22, so that the welding strength is favorably improved, and the safety, the low internal resistance and the like of the pole piece are further improved. Specifically, due to the presence of the rubber coating 1, there may be a gap between the junction of the first part 211 and the second part 212 and the junction of the third part 221 and the fourth part 222, one end of the gap being connected to the rubber coating, and the other end being connected to the weld formed by the first part 212 and the third part 222 (as shown in fig. 1 to 4), and a tab being welded to the weld. In specific implementation, the surface areas of the first portion 211 and the third portion 221 may be designed according to the size of the tab, and generally, the tab may be welded to the first portion 211 and the third portion 221. The welding method of the tab may be ultrasonic welding, or may be other conventional methods in the art, which is not limited in this respect.
The properties of the current collector are not particularly limited in the present invention, and the current collector may be a positive current collector or a negative current collector, and in specific implementation, the first metal layer 21 and the second metal layer 22 made of suitable materials may be selected according to the properties of the current collector. Specifically, in some embodiments, the composition material of the first metal layer 21 and the second metal layer 22 may include at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, aluminum-zirconium alloy, and stainless steel.
In another aspect of the present invention, there is provided a method for preparing a current collector, including: applying a glue to one surface of at least one of the first portion of the first metal layer and the third portion of the second metal layer; compounding the first metal layer and the second metal layer to connect the first part and the third part via the glue coating layer; and welding the second part of the first metal layer and the fourth part of the second metal layer together to obtain the current collector.
Specifically, parameters such as the shapes and the surface areas of the first metal layer and the second metal layer are equal, a glue coating area (a first part and/or a third part) can be set according to the area size of a preset glue coating layer, glue with a bonding effect is coated on the glue coating area, then the first metal layer and the second metal layer can be compounded by adopting a compounding machine, so that the first metal layer and the second metal layer are connected through the glue coating layer, during compounding, the surface, coated with the glue layer, of the first metal layer and/or the second metal layer is positioned between the first metal layer and the second metal layer, and the edge of the first metal layer is aligned with the edge of the second metal layer; after compounding, the second portion of the first metal layer and the fourth portion of the second metal layer may be welded together using ultrasonic welding and/or laser welding to produce the current collector. The processes of compounding, ultrasonic welding, laser welding and the like can be conventional processes in the field, and the invention is not particularly limited in this regard and is not described in detail.
In some embodiments, before the coating, the method further includes performing a pretreatment on the first metal layer and/or the second metal layer, the pretreatment including: and cleaning the surfaces of the first metal layer and the second metal layer by sequentially adopting an organic solvent and an acid solution, and then modifying the surfaces of the first metal layer and the second metal layer by adopting a coupling agent. Through the pretreatment process, the subsequent manufacturing of the current collector is facilitated, and the safety, low internal resistance and other characteristics of the current collector are improved. Wherein, after being cleaned by the acid solution, the pretreatment process can be further finished by further adopting water for cleaning, then adopting a coupling agent for modification treatment, then adopting water for cleaning, and drying by cold air.
Specifically, the organic solvent used may include at least one of ethanol, acetonitrile, acetone, dimethyl carbonate, ethylene glycol dimethyl ether; the acid solution may specifically be a dilute acid solution, for example, including at least one of dilute sulfuric acid, dilute hydrochloric acid, dilute acetic acid, and dilute phosphoric acid; the coupling agent may include at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zirconate coupling agent, a bimetallic coupling agent, a phosphate coupling agent, and a borate coupling agent, and generally preferably includes at least one of a silane coupling agent and a titanate coupling agent, and preferably, the silane coupling agent may include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-methacryloxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, a, At least one of diethylenetriaminopropyltriethoxysilane, 3-thiocyanopropyltriethoxysilane, 3-chloropropylmethyldimethoxysilane and aniline methyltriethoxysilane, wherein the titanate coupling agent comprises at least one of tetraisopropylbis (dioctylphosphite acyloxy) titanate, isopropoxytris (ethylenediamine-N-ethoxy) titanate and isopropyltris (dioctylphosphato) titanate.
In some embodiments, after welding the second portion of the first metal layer and the fourth portion of the second metal layer together, the first portion of the first metal layer and the third portion of the second metal layer may be further subjected to an etching thinning process to reduce the thickness of at least a part of the first portion and reduce the thickness of at least a part of the third portion, so as to obtain a current collector having a first portion thickness smaller than the second portion thickness and a third portion thickness smaller than the fourth portion thickness, or obtain a current collector having a second portion thickness and a first unreduced portion thickness larger than the first reduced portion thickness and a second unreduced portion thickness larger than the second reduced portion thickness.
Specifically, the above etching reduction treatment may be performed by chemical etching or electrochemical etching, chemical etching is generally preferred, and in the specific implementation, an appropriate metal etching solution may be selected according to the metal material of the first metal layer and the second metal layer, for example, when the material is aluminum, an aluminum etching solution may be selected, and the aluminum etching solution may include a strong alkali solution, for example, a solution whose main component is an alkali metal hydroxide (such as sodium hydroxide); when the material is copper, a copper etchant may be selected, and the copper etchant may include an acid solution, for example, an acid solution whose main component is nitric acid; when the material is nickel, a nickel etchant may be selected, and the nickel etchant may include an acid solution, for example, an acid solution whose main component is nitric acid.
For example, in some embodiments, the etch thinning process may include: coating a protective layer on the areas (such as the second part, the fourth part, the first non-thinned part and the second non-thinned part) which are not required to be thinned of the composite substrate formed after welding, then placing the composite substrate in a metal corrosive liquid, enabling the preset thinned area to be in contact reaction with the metal corrosive liquid, and realizing corrosion thinning treatment on the preset thinned area (such as the first thinned part and the third thinned part), or inserting the composite substrate into an electrolytic bath filled with electrolyte after coating the protective layer on the areas which are not required to be thinned of the composite substrate, and enabling the preset thinned area to be subjected to electrochemical corrosion to realize corrosion thinning treatment on the preset thinned area (such as the first thinned part and the third thinned part); the concentration of the metal corrosive liquid, the corrosion treatment time and other conditions or the electrochemical corrosion conditions can be regulated and controlled according to the preset parameters such as the thickness of the thinned area.
Specifically, the protective layer is used for avoiding the area which does not need to be thinned from being thinned by metal corrosion liquid or electrochemical corrosion, and specifically may be a polymer protective layer, the raw material of which includes at least one of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polycarbonate and polystyrene, and the thickness of the protective layer may be 0.5 to 1.5 μm. In specific implementation, after the metal corrosion liquid corrosion or the electrochemical corrosion is finished, the composite matrix is taken out, and then the protective layer on the composite matrix is dissolved and removed by adopting an organic solvent, wherein the organic solvent can comprise at least one of acetone, N-methylpyrrolidone (NMP) and toluene.
In the above preparation process, the current collector may be prepared by coating glue on only one of the first part of the first metal layer and the third part of the second metal layer, or coating glue on both of them, and then performing compounding, welding and other treatments.
For example, in some embodiments, the process of preparing the current collector comprises: gluing the surface of the first part of the first metal layer, then compounding the first metal layer and the second metal layer to ensure that the first part of the metal layer is connected with the third part of the second metal layer through a gluing layer formed by gluing, and then welding the second part of the first metal layer and the fourth part of the second metal layer together to obtain a current collector; wherein, the surface area of the first part accounts for at least 50% of the surface area of the first metal layer (namely the surface area of the glue coating accounts for at least 50% of the surface area of the first metal layer), during compounding, the glue coating is positioned between the first metal layer and the second metal layer, the edges of the first metal layer and the second metal layer are completely aligned, and in the current collector formed after compounding and welding, the thickness of the glue coating between the first part and the third part is 0.5-5 μm.
In other embodiments, the preparing of the current collector comprises: applying glue to one surface of a first portion of the first metal layer (referred to as a first glue), and applying a second glue to one surface of a third portion of the second metal layer (referred to as a second glue); then compounding the first metal layer and the second metal layer to enable the first part of the first metal layer and the third part of the second metal layer to be connected through a first glue coating layer formed by the first glue coating and a second glue coating layer formed by the second glue coating, and then welding the second part of the first metal layer and the fourth part of the second metal layer together to obtain a current collector; wherein the surface area of the first part accounts for at least 50% of the surface area of the first metal layer (i.e. the surface area of the first glue coating layer accounts for at least 50% of the surface area of the first metal layer), and the surface area of the third part accounts for at least 50% of the surface area of the second metal layer (i.e. the surface area of the second glue coating layer accounts for at least 50% of the surface area of the second metal layer), and during compounding, the first glue coating layer and the second glue coating layer are mutually attached, and the edges of the first metal layer and the second metal layer are completely aligned; in the current collector formed by compounding and welding, the total thickness of the glue coating layers formed by the first glue coating layer and the second glue coating layer is 0.5-5 mu m.
In another aspect of the present invention, a pole piece is provided, which includes the current collector and an active material layer on at least one surface of the current collector; and the pole lug is welded on a welding part formed by the first part of the first metal layer and the third part of the second metal layer of the current collector.
Specifically, the electrode sheet may be a positive electrode sheet or a negative electrode sheet, the raw material of the active material layer may include an active material, a conductive agent and a binder, and when the electrode sheet is a positive electrode sheet, the active material may be a positive electrode active material conventional in the art, including, for example, lithium cobaltate; when the pole piece is a negative pole piece, the active material can be a conventional negative active material, for example, at least one of a graphite material and a silicon-based material; the conductive agent and the binder may also be conventional materials in the art, for example, the conductive agent may include acetylene black, and the binder may include at least one of polyvinylidene fluoride (PVDF), Styrene Butadiene Rubber (SBR), and sodium carboxymethylcellulose (CMC).
The pole piece can be prepared by adopting a conventional method in the field, for example, a coating method, and in the specific implementation, the slurry comprising the raw material of the active material layer can be coated on a current collector, then the active material layer is formed on the current collector through drying and rolling, and then the pole piece is cut into the pole piece according to the preset parameters of the shape, the size and the like of the pole piece; wherein, the first part of the first metal layer and the third part of the second metal layer are not coated with slurry for welding the tab.
The invention also provides a battery, which comprises the pole piece.
The battery of the present invention may include the positive electrode sheet having the above structural design (i.e., the above electrode sheet is a positive electrode sheet), or include the negative electrode sheet having the above structural design (i.e., the above electrode sheet is a negative electrode sheet), or may include both the positive electrode sheet having the above structural design and the negative electrode sheet having the above structural design (i.e., the above electrode sheet includes a positive electrode sheet and a negative electrode sheet). When the pole piece is a positive pole piece, the battery also comprises a negative pole piece which can be a negative pole piece conventional in the field; when the pole piece is a negative pole piece, the battery also comprises a positive pole piece which can be a positive pole piece conventional in the field. The battery further includes a separator disposed between the positive and negative plates for separating the positive and negative plates, which may also be a separator conventional in the art.
Specifically, the battery of the present invention may be a lithium ion battery, which may be a wound or laminated battery, and may be manufactured according to a conventional method in the art, for example, a positive plate, a separator, and a negative plate may be sequentially stacked, and then wound (or laminated) to form a battery cell, and then the battery is manufactured through processes of packaging, liquid injection, formation, capacity division, OCV (open circuit voltage test), and the like, which are all conventional operations in the art.
The present invention will be further illustrated by the following specific examples and comparative examples. Unless otherwise specified, the reagents, materials and apparatuses used in the following description are all conventional reagents, conventional materials and conventional apparatuses, and are commercially available, and the reagents and materials may be synthesized by a conventional synthesis method. The ultrasonic seam welder used in the following is from Yaozao ultrasonic intelligent mechanical Co., Ltd, Dongguan, the laser welder (model ZXL-200W) is from Zhengxin laser technology Co., Ltd, the ultrasonic metal welder (model UM-20) is from Site high energy electronic technology Co., Ltd, Shenzhen, and the tension tester (model LK-108A) is from force control instrument technology Co., Ltd.
Examples 1 to 8
The current collectors (C1-C8) of examples 1-8 have the structure shown in fig. 1 and are prepared according to the following process, wherein the conditions of E1, E2, D1, D2, D3, phi, rubber coating raw materials and the like are shown in table 1:
(1) pretreatment:
washing the copper foil with the thickness of D1 with acetone for 3min, then washing with 0.1mol/L dilute sulfuric acid for 2min, then washing with deionized water for 2min, then treating with 0.5% aqueous solution of a coupling agent E1 for 1h, then washing with deionized water for 10min, and finally drying with cold air to obtain a copper foil A1;
washing the copper foil with the thickness of D2 with acetone for 3min, then washing with 0.1mol/L dilute sulfuric acid for 2min, then washing with deionized water for 2min, then treating with 0.5% aqueous solution of a coupling agent E2 for 1h, then washing with deionized water for 10min, and finally drying with cold air to obtain a copper foil B1;
(2) gluing and compounding: coating glue on one surface of a first part of a copper foil A1, and then compounding the copper foil A1 and the copper foil B1 by a compounding machine to bond the first part of the copper foil A1 and a third part of the copper foil B1 together through a glue coating layer formed by the coating glue; the copper foil A1 further comprises a second part which is not coated with glue, the first part is positioned at one end of the copper foil A1, the second part is positioned at the other end of the copper foil A1, the surface area of the first part accounts for phi of the surface area of the copper foil A1, the copper foil B1 further comprises a fourth part which is not coated with glue, the third part is positioned at one end of the copper foil B1, the fourth part is positioned at the other end of the copper foil B1, and the surface area of the third part accounts for phi of the surface area of the copper foil B1; during compounding, the edges of the copper foil A1 and the copper foil B1 are aligned;
(3) welding: welding the second part of the copper foil A1 and the fourth part of the copper foil B1 together by using an ultrasonic seam welder to obtain a current collector; wherein the thickness of the glue coat between the first portion of copper foil a1 and the third portion of copper foil B1 was D3.
TABLE 1
Figure BDA0002977727380000121
Examples 9 to 16
The current collectors (C9-C16) of examples 9-16, whose structures are shown in fig. 2, were prepared according to the following procedures, wherein the conditions of E1, E2, D1, D2, D3, Φ, D, raw material for coating, etc. are shown in table 2:
(1) pretreatment:
washing the aluminum foil with the thickness of D1 with acetonitrile for 3min, then washing with 0.02mol/L diluted acetic acid for 1min, then washing with deionized water for 2min, then treating with 0.1% coupling agent E1 water solution for 1h, then washing with deionized water for 10min, and finally drying with cold air to obtain aluminum foil A1;
washing the aluminum foil with the thickness of D2 with acetonitrile for 3min, then washing with 0.02mol/L diluted acetic acid for 1min, then washing with deionized water for 2min, then treating with 0.1% coupling agent E2 water solution for 1h, then washing with deionized water for 10min, and finally drying with cold air to obtain an aluminum foil B1;
(2) aluminum foil a1 and aluminum foil B1 were glue-coated and compounded with reference to step (2) of examples 1 to 8;
(3) the aluminum foil a1 and the aluminum foil B1 were welded according to the step (3) of examples 1 to 8, to obtain a composite substrate;
(4) and (3) corroding and thinning the composite base body part in different areas:
coating a polymer protective layer (the raw material is PVDF-HFP) with the thickness of 1 mu m on the second part, the first non-thinned part of the first part, the fourth part of the aluminum foil B1 and the second non-thinned part of the third part of the aluminum foil A1 by adopting a coating machine, then immersing the composite matrix into an aluminum foil corrosion solution, corroding and thinning the first thinned part of the first part of the aluminum foil A1 and the second thinned part of the third part of the aluminum foil B1 to ensure that the thicknesses of the first thinned part and the second thinned part are respectively D1-2 and D2-2, then taking the composite matrix out of the aluminum foil corrosion solution, and dissolving and removing the protective layer on the composite matrix by adopting acetone to prepare a current collector; wherein, in the direction from the first thinning part to the first non-thinning part, the length of the first non-thinning part and the second non-thinning part is d.
TABLE 2
Figure BDA0002977727380000141
Examples 17 to 24
The current collectors (C17-C24) of examples 17-24 are shown in fig. 3 and were prepared as follows, wherein the conditions of E1, E2, D1, D2, D3, phi, coating material, etc. are shown in table 3:
(1) pretreatment:
washing the aluminum foil with the thickness of D1 with ethanol for 3min, then washing with 0.01mol/L diluted phosphoric acid for 1min, then washing with deionized water for 2min, then treating with 1% of a coupling agent E1 aqueous solution for 0.5h, then washing with deionized water for 10min, and finally drying with cold air to obtain an aluminum foil A1;
washing the aluminum foil with the thickness of D2 with ethanol for 3min, then washing with 0.01mol/L diluted phosphoric acid for 1min, then washing with deionized water for 2min, then treating with 0.5% aqueous solution of a coupling agent E2 for 1h, then washing with deionized water for 10min, and finally drying with cold air to obtain an aluminum foil B1;
(2) gluing and compounding: first glue coating (the thickness of the glue coating is D3) is carried out on one surface of the first part of the aluminum foil A1, second glue coating (the thickness of the glue coating is D3) is carried out on one surface of the third part of the aluminum foil B1, then the aluminum foil A1 and the aluminum foil B1 are compounded through a compounding machine, and the first part of the aluminum foil A1 and the third part of the aluminum foil B1 are bonded together through a first glue coating formed by the first glue coating and a second glue coating formed by the second glue coating; the aluminum foil A1 is also provided with a second part without glue, the first part is positioned at one end of the aluminum foil A1, the second part is positioned at the other end of the aluminum foil A1, the surface area of the first part accounts for phi of the surface area of the aluminum foil A1, the aluminum foil B1 is also provided with a fourth part without glue, the third part is positioned at one end of the aluminum foil B1, the fourth part is positioned at the other end of the aluminum foil B1, and the surface area of the third part accounts for phi of the surface area of the aluminum foil B1; during compounding, the first glue coating layer and the second glue coating layer are mutually attached, and the edges of the aluminum foil A1 and the aluminum foil B1 are aligned;
(4) welding: welding the third part of the aluminum foil A1 and the fourth part of the aluminum foil B1 together by using a laser welding machine to obtain a current collector; wherein the thickness of the glue coat between the first portion of aluminium foil a1 and the third portion of aluminium foil B1 was D3.
TABLE 3
Figure BDA0002977727380000151
Examples 25 to 32
The current collectors (C17-C24) of examples 25-32 are shown in fig. 4 and were prepared as follows, wherein the conditions of E1, E2, D1, D2, D3, Φ, D, raw material for coating, etc. are shown in table 4:
(1) pretreatment:
washing the copper foil with the thickness of D1 with glycol dimethyl ether for 3min, then washing with 1mol/L diluted hydrochloric acid for 1min, then washing with deionized water for 5min, then treating with 5% of a coupling agent E1 aqueous solution for 0.2h, then washing with deionized water for 20min, and finally drying with cold air to obtain a copper foil A1;
washing the copper foil with the thickness of D2 for 3min by using dimethyl carbonate, then washing for 1min by using 1mol/L diluted hydrochloric acid, then washing for 5min by using deionized water, then treating for 0.5h by using 2% of a coupling agent E2 aqueous solution, then washing for 15min by using deionized water, and finally drying by using cold air to obtain a copper foil B1;
(2) copper foil A1 and copper foil B1 were subjected to adhesive-coated compounding with reference to step (2) of examples 17 to 24;
(3) copper foil a1 and copper foil B1 were welded according to the step (3) of examples 17 to 24 to obtain a composite substrate;
(4) and (3) corroding and thinning the composite base body part in different areas:
coating a polymer protective layer (polycarbonate is used as a raw material) with the thickness of 2 mu m on the second part, the first non-thinned part of the first part, the fourth part of the copper foil B1 and the second non-thinned part of the third part of the copper foil A1 by adopting a coating machine, then immersing the composite matrix into a copper foil corrosion solution, corroding and thinning the first thinned part of the first part of the copper foil A1 and the second thinned part of the third part of the copper foil B1 to ensure that the thicknesses of the first thinned part and the second thinned part are respectively D1-2 and D2-2, then taking out the composite matrix from the copper foil corrosion solution, and dissolving and removing the protective layer on the composite matrix by adopting NMP to prepare a current collector; wherein, in the direction from the first thinning part to the first non-thinning part, the length of the first non-thinning part and the second non-thinning part is d.
TABLE 4
Figure BDA0002977727380000171
Examples 33 to 40
The current collectors (C33-C40) of examples 33-40, which have the structure shown in fig. 2, were prepared according to the following procedure, wherein the types of metal foils (a1/B1), E1, E2, D1, D2, D3, phi, D, and the conditions of the raw material for the adhesive layer are shown in table 5:
(1) with reference to the pretreatment process of the aluminum foil a1 in step (1) of examples 9 to 16, the metal foil a1 was pretreated;
with reference to the pretreatment process of the aluminum foil B1 in step (1) of examples 9 to 16, the metal foil B1 was pretreated;
(2) the metal foil a1 and the metal foil B1 were subjected to glue coating compounding with reference to the step (2) of examples 9 to 16;
(3) welding the metal foil a1 and the metal foil B1 according to the step (3) of examples 9 to 16 to obtain a composite substrate;
(4) and (3) corroding and thinning the composite base body part in different areas:
coating a polymer protective layer (polystyrene is used as a raw material) with the thickness of 0.9 mu m on the second part, the first non-thinned part of the first part, the fourth part of the copper foil B1 and the second non-thinned part of the third part of the copper foil A1 by using a coating machine, then immersing the composite matrix into electrolyte of an electrolytic bath for electrochemical corrosion, corroding and thinning the first thinned part of the first part of the metal foil A1 and the second thinned part of the third part of the metal foil B1 to ensure that the thicknesses of the first thinned part and the second thinned part are respectively D1-2 and D2-2(D1-2 and D2-2 are equal), then taking out the composite matrix from the electrolytic bath, and dissolving and removing the protective layer on the composite matrix by using toluene to prepare a current collector; wherein, in the direction from the first thinning part to the first non-thinning part, the length of the first non-thinning part and the second non-thinning part is d.
TABLE 5
Figure BDA0002977727380000181
Comparative examples 41 to 42
Comparative example 41 a commercial aluminum foil having a thickness of 12 μm, designated C41;
comparative example 42 a commercial copper foil having a thickness of 5 μm, designated C42, was used as the current collector.
Comparative examples 43 to 44
The current collectors (C43-C44) of comparative examples 43-44 were three-layer composite structures (as shown in fig. 5) consisting of a first metal layer 21 ', a polymer layer 1 ', and a second metal layer 22 ', in which,
comparative example 43: respectively depositing 1.5 mu m metal aluminum layers on two sides (namely two surfaces) of a polypropylene base film with the thickness of 6 mu m by adopting an electron beam evaporation mode to prepare a current collector which is marked as C43;
comparative example 44: and respectively depositing 1-micron metal copper layers on two sides (namely two surfaces) of the polyethylene terephthalate base film with the thickness of 4 microns by adopting a magnetron sputtering method to prepare a current collector, which is marked as C44.
Application examples
1. Preparation of Pole piece J1-J54
The properties of the pole pieces J1-J54, the current collectors used, are shown in Table 6 and were prepared as follows:
when the pole piece property is positive (i.e. the pole piece is a positive pole piece): 97 parts of lithium cobaltate, 1.5 parts of acetylene black, 1.5 parts of PVDF and 60 parts of NMP are stirred for 4 hours under vacuum by a double planetary stirrer under the conditions of revolution of 30r/min and rotation of 1500r/min, and are dispersed into uniform anode slurry, then the anode slurry is coated on a current collector, dried (baked for about 30min) at 120 ℃, and then rolled under 40 tons of rolling pressure; the method comprises the following steps that active substance layers are not coated on a first part of a first metal layer and a third part of a second metal layer of a current collector, and the active substance layers are used for welding a positive electrode lug (aluminum lug) and obtaining a positive plate after the positive electrode lug is welded;
when the pole piece property is negative (i.e. the pole piece is a negative pole piece): stirring 97.5 parts of graphite, 1 part of acetylene black, 0.5 part of CMC, 1 part of SBR and 100 parts of deionized water for 4 hours in vacuum by a double-planet stirrer under the conditions of revolution of 30r/min and rotation of 1500r/min, dispersing into uniform negative slurry, then coating the negative slurry on a current collector, drying at 100 ℃ (baking for about 30min), and then rolling under the rolling pressure of 45 tons; the method comprises the following steps of coating active substance layers on a first part of a first metal layer and a third part of a second metal layer of a current collector, welding a negative pole lug (nickel lug), and obtaining a negative pole piece after welding the negative pole lug;
in the process, an ultrasonic metal welding machine is adopted to weld the lug, and the welding conditions are as follows: welding power 3000W, welding frequency 20kHz, welding amplitude 40 μm, welding time 0.42s and welding pressure 0.3 MPa; the width of the aluminum tab is 6mm, and the thickness of the aluminum tab is 0.1 mm; the width D of the nickel tab is 6mm, and the thickness of the nickel tab is 0.1 mm.
Testing the welding strength of the tab on the pole piece J1-J54: the tab welded on the pole piece is clamped by a clamp, then the pulling force value N of the tab pulled off from the current collector is tested by a pulling force tester, the tab welding strength F is calculated to be N/D (N is the pulling force value, D is the tab width), and the result is shown in table 6.
TABLE 6
Figure BDA0002977727380000201
2. Preparation of Battery K1-K30
Batteries K1-K30 were wound lithium ion batteries, each made from the above-described tab J1-J54, along with a Polyethylene (PE) porous separator for spacing the positive and negative tabs, according to conventional procedures in the art, and the positive and negative tabs used in each battery are shown in table 7.
TABLE 7
Battery with a battery cell Positive plate Negative plate Battery with a battery cell Positive plate Negative plate
K1 J9 J1 K17 J33 J37
K2 J10 J2 K18 J34 J38
K3 J11 J3 K19 J35 J39
K4 J12 J4 K20 J36 J40
K5 J13 J5 K21 J41 J1
K6 J14 J6 K22 J41 J2
K7 J15 J7 K23 J41 J3
K8 J16 J8 K24 J41 J4
K9 J17 J25 K25 J17 J42
K10 J18 J26 K26 J18 J42
K11 J19 J27 K27 J19 J42
K12 J20 J28 K28 J20 J42
K13 J21 J29 K29 (comparison example 1) J41 J42
K14 J22 J30 K30 (comparison example 2) J43 J44
K15 J23 J31
K16 J24 J32
3. Battery performance testing
According to GB/T31485-; the internal resistances of batteries K1-K30 were also measured and are shown in Table 8.
TABLE 8
Battery with a battery cell Needle penetration Rate (%) Heating passage (%) Overcharge pass rate (%) Internal resistance (m omega)
K1 100％ 100％ 100％ 77
K2 100％ 100％ 100％ 74
K3 100％ 100％ 100％ 75
K4 100％ 100％ 100％ 76
K5 100％ 100％ 100％ 72
K6 100％ 100％ 100％ 83
K7 100％ 100％ 100％ 69
K8 100％ 100％ 100％ 71
K9 100％ 100％ 100％ 65
K10 100％ 100％ 100％ 64
K11 100％ 100％ 100％ 65
K12 100％ 100％ 100％ 65
K13 100％ 100％ 100％ 63
K14 100％ 100％ 100％ 75
K15 100％ 100％ 100％ 61
K16 100％ 100％ 100％ 68
K17 100％ 100％ 100％ 78
K18 100％ 100％ 100％ 80
K19 100％ 100％ 100％ 81
K20 100％ 100％ 100％ 95
K21 100％ 100％ 100％ 62
K22 100％ 100％ 100％ 61
K23 100％ 100％ 100％ 61
K24 100％ 100％ 100％ 60
K25 100％ 100％ 100％ 58
K26 100％ 100％ 100％ 57
K27 100％ 100％ 100％ 59
K28 100％ 100％ 100％ 58
K29 0％ 0％ 0％ 64
K30 90％ 100％ 90％ 157
As can be seen from tables 6 and 8, the current collectors C1 to C40 have higher tab welding strength than the current collectors C41 to C44, so that the safety of the battery can be significantly improved, and the characteristics of the battery, such as low internal resistance, can be ensured. Specifically, the battery K29 formed by using the commercial conventional pure metal current collector is completely ignited and burnt during the safety performance test and cannot pass the safety performance test, the needling pass rate and the overcharge pass rate of the battery K30 formed by using the metal layer-polymer-metal layer three-layer composite structure current collector are 90%, the internal resistance is as high as 157m omega, and the needling pass rate, the heating pass rate and the overcharge pass rate of the batteries K1-K28 are all 100%, and meanwhile, the battery has low internal resistance and simultaneously has the characteristics of excellent safety, low internal resistance and the like.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The current collector is characterized by comprising a first metal layer and a second metal layer compounded with the first metal layer, wherein the first metal layer is provided with a first part and a second part, the second metal layer is provided with a third part and a fourth part layer, the first part and the third part are connected through an adhesive coating, and the second part and the fourth part are connected through welding.
2. The current collector of claim 1, wherein the surface area of the first portion is 50-98% of the surface area of the first metal layer, and the surface area of the third portion is 50-98% of the surface area of the second metal layer.
3. The current collector of claim 1, wherein the first portion comprises a first thinned portion having a thickness less than a thickness of the second portion; and/or the third portion comprises a second thinned portion having a thickness less than a thickness of the fourth portion.
4. The current collector of claim 3, wherein the first thinning is formed by an etching thinning of the first metal layer and/or wherein the second thinning is formed by an etching thinning of the second metal layer.
5. The current collector of claim 4, wherein a first non-thinned region of the first metal layer, including the second portion, is provided with a protective layer for preventing the first non-thinned region from being thinned by the corrosion when the corrosion thinning process is performed;
and/or the presence of a gas in the gas,
when carrying out the corrosion attenuate treatment, include on the second metal level the non-attenuate region of second of fourth part is provided with the protective layer, the protective layer is used for preventing the non-attenuate region quilt of second the corrosion attenuate.
6. The current collector of claim 1 or 3,
the first portion comprises a first thinned portion distal from the second portion and a first non-thinned portion proximal to the second portion, the first non-thinned portion having a length d in a direction along the first thinned portion to the first non-thinned portion1，0.3mm≤d13mm or less, the thickness of the second part and the thickness of the first non-thinned part are greater than the thickness of the first thinned part; and/or the presence of a gas in the gas,
the third portion comprises a second thinned portion distal from the fourth portion and a second non-thinned portion proximal to the fourth portion, the second non-thinned portion having a length d in a direction along the second thinned portion to the second non-thinned portion2，0.3mm≤d2The thickness of the fourth part and the thickness of the second non-thinned part are greater than the thickness of the second thinned part.
7. The current collector of claim 6, wherein the first and second thinned portions each have a thickness of 0.1-5 μm, and wherein the second portion, the first non-thinned portion, the fourth portion, and the second non-thinned portion each have a thickness of 1-20 μm.
8. The current collector of claim 1, wherein the thickness of the glue layer is 0.5-5 μm.
9. The method for preparing a current collector of any one of claims 1 to 8, comprising: applying a glue to one surface of at least one of the first portion of the first metal layer and the third portion of the second metal layer; compounding the first metal layer and the second metal layer to ensure that the first part is connected with the third part through a glue coating layer formed by gluing; and welding the second part of the first metal layer and the fourth part of the second metal layer together to obtain the current collector.
10. A pole piece comprising the current collector of any one of claims 1 to 8 and an active material layer on at least one surface of the current collector; still be equipped with utmost point ear on the polar plate, utmost point ear welding is in the weld part that the first part of the first metal level of mass flow body and the third part of second metal level formed.
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