WO2023159373A1 - 极片、电极组件及二次电池 - Google Patents

极片、电极组件及二次电池 Download PDF

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Publication number
WO2023159373A1
WO2023159373A1 PCT/CN2022/077402 CN2022077402W WO2023159373A1 WO 2023159373 A1 WO2023159373 A1 WO 2023159373A1 CN 2022077402 W CN2022077402 W CN 2022077402W WO 2023159373 A1 WO2023159373 A1 WO 2023159373A1
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WO
WIPO (PCT)
Prior art keywords
pole piece
layer
current collector
active material
secondary battery
Prior art date
Application number
PCT/CN2022/077402
Other languages
English (en)
French (fr)
Inventor
吴志阳
何昌盛
李克强
刘萧松
Original Assignee
宁德时代新能源科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to KR1020237021942A priority Critical patent/KR20230128469A/ko
Priority to CN202280036289.5A priority patent/CN117378056A/zh
Priority to JP2023540675A priority patent/JP2024510696A/ja
Priority to EP22927668.8A priority patent/EP4325593A1/en
Priority to PCT/CN2022/077402 priority patent/WO2023159373A1/zh
Publication of WO2023159373A1 publication Critical patent/WO2023159373A1/zh
Priority to US18/518,068 priority patent/US20240088362A1/en

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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • 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
    • H01M4/62—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
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/72—Grids
    • 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
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/72—Grids
    • H01M4/74—Meshes or woven material; Expanded metal
    • 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
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/80—Porous plates, e.g. sintered carriers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/211—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for pouch cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/10—Batteries in stationary systems, e.g. emergency power source in plant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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

Definitions

  • the present application relates to the field of batteries, in particular to a pole piece, an electrode assembly and a secondary battery.
  • secondary batteries have been widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as electric tools, electric bicycles, Electric motorcycles, electric vehicles, consumer electronics, military equipment, aerospace and other fields. Due to the great development of secondary batteries, higher requirements have been put forward for their energy density, cycle performance and safety performance.
  • a current collector is disclosed in the prior art, which includes a dense support layer and a dense conductive layer disposed on at least one surface of the support layer.
  • the above-mentioned current collector cannot pass through the traditional tab forming structure, and can form a conductive structure along the thickness direction of the battery. Therefore, it is necessary to use ultrasonic welding to weld the metal tab on the edge of the current collector. In this way, in the above-mentioned current collector, there is a short circuit caused by metal welding when the metal tab is welded to the current collector, resulting in poor safety of the secondary battery using the current collector, and metal slag falling into other areas during welding, resulting in There is a problem that the internal resistance of the secondary battery increases.
  • the present application is made in view of the above-mentioned technical problems, and its purpose is to provide a pole piece, an electrode assembly, a secondary battery, a battery module, a battery pack, and an electrical device, which can reliably prevent metal welding through during welding and cause short circuit, thereby improving the safety of the secondary battery using the pole piece and reducing the internal resistance of the secondary battery.
  • the present application provides a pole piece, an electrode assembly, a secondary Batteries, battery modules, battery packs and electrical devices.
  • the first aspect of the present application provides a pole piece, including a current collector, an active material layer disposed on one surface of the current collector, and an electrical connection member electrically connected to the current collector, the active material layer Set on the main part of the current collector, the electrical connection member is welded to the current collector at the edge of the current collector.
  • This welded connection area is called a transfer welding area.
  • the current collector includes a support layer and A conductive layer disposed on one surface of the support layer, wherein the pole piece further includes a first insulating layer disposed on the other surface of the current collector and extending from the pole The sheet covers at least the entirety of the transfer welding region when viewed in the thickness direction.
  • the present application arranges on the other surface of the current collector the first insulating layer that covers at least the entirety of the transfer welding area when viewed from the thickness direction of the pole piece, thereby soldering and connecting the electrical connection on one surface side of the current collector.
  • the first insulating layer on the other surface of the current collector acts as a protection against debris and particles falling into the diaphragm area, it can also reliably prevent metal welding through during welding and cause short circuit, thereby improving the safety of the secondary battery using the pole piece and reducing the internal resistance of the secondary battery.
  • the support layer is made of an insulating material having a fibrous hole structure.
  • the ion permeability of the support layer can be improved, and the electrochemical performance can be effectively improved.
  • the supporting layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film or a multilayer composite film thereof. Accordingly, by constituting the support layer with a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, it is possible to reliably form a support layer with high ion permeability.
  • the edge of the first insulating layer coincides with the edge of the active material layer.
  • the transfer welding region where the electrical connection member is welded is preferably located outside the edge of the active material layer when viewed from the thickness direction of the pole piece. The edge of the first insulating layer and the edge of the active material layer overlap when viewed from the thickness direction of the pole piece, which can reliably ensure that the first insulation layer covers the entire transfer welding area when viewed from the thickness direction of the pole piece.
  • the first insulating layer is made of resin material and is the same material as the supporting layer. Thereby, the ion permeability of the first insulating layer can be improved, and the electrochemical performance can be effectively improved.
  • the first insulating layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film or a multilayer composite film thereof, or the first insulating layer is an adhesive or a resin material. Accordingly, by constituting the first insulating layer with a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, it is possible to reliably constitute a first insulating layer with high ion permeability.
  • the first insulating layer is formed with an adhesive or a resin material, and the insulating layer can be easily formed by coating or the like.
  • the pole piece further includes a second insulating layer, the second insulation layer is disposed on one surface of the electrical connection member and covers at least the pole piece when viewed from the thickness direction of the pole piece.
  • the entirety of the transfer welding area can be used to fill the riveting hole caused by welding and prevent the slag generated by welding and the particles falling in the subsequent process from falling into the riveting hole, thereby preventing the occurrence of hi-po defects and reducing the The DC internal resistance of the secondary battery.
  • the second insulating layer is an adhesive or a resin material. Accordingly, it is possible to reliably fill the caulking hole caused by the soldering with an adhesive or a resin material.
  • an undercoat layer is disposed between the active material layer and the current collector; optionally, the undercoat layer has a width smaller than that of the active material layer by 1mm to 3mm.
  • the undercoat can improve The current flow capacity and electrochemical performance of the pole piece.
  • the width of the undercoat layer is 1 mm to 3 mm smaller than the width of the active material layer, it is possible to prevent the electrical connection member from contacting the undercoat layer to prevent poor soldering and false soldering.
  • the second aspect of the present application provides an electrode assembly, which includes a first pole piece and a second pole piece, one pole piece of the first pole piece and the second pole piece is the first aspect of the present application In the pole piece, the support layer of the one pole piece in the first pole piece and the second pole piece and the other pole piece in the first pole piece and the second pole piece Close contact mode set.
  • the third aspect of the present application also provides an electrode assembly, which includes a first pole piece and a second pole piece, and the first pole piece and the second pole piece are respectively described in the first aspect of the present application.
  • the pole piece is set in such a way that the support layer of the first pole piece is in close contact with the active material layer of the second pole piece, and the support layer of the second pole piece is in contact with the first pole piece
  • the active material layers are arranged in close contact.
  • a fourth aspect of the present application provides a secondary battery, wherein the secondary battery includes the pole piece described in the first aspect of the present application or the electrode assembly described in the second aspect or the third aspect of the present application.
  • a fifth aspect of the present application provides a battery module, wherein the battery module includes the secondary battery described in the fourth aspect of the present application.
  • a sixth aspect of the present application provides a battery pack, wherein the battery pack includes the battery module described in the fifth aspect of the present application.
  • the seventh aspect of the present application provides an electric device, wherein the electric device includes the secondary battery described in the fourth aspect of the present application, the battery module described in the fifth aspect of the present application, and the At least one of the battery packs described in the sixth aspect.
  • FIG. 1 is a cross-sectional view of a pole piece according to an embodiment of the present application.
  • Fig. 2 is a top view of a pole piece according to an embodiment of the present application.
  • Fig. 3 is a bottom view of a tab portion of a pole piece according to an embodiment of the present application.
  • Fig. 4 is a top view of a tab portion of a pole piece according to an embodiment of the present application.
  • FIG. 5 is a cross-sectional view of an electrode assembly according to an embodiment of the present application.
  • FIG. 6 is a top view of the electrode assembly shown in FIG. 5 after being wound.
  • FIG. 7 is a cross-sectional view of an electrode assembly according to an embodiment of the present application.
  • FIG. 8 is a top view of the electrode assembly shown in FIG. 5 after being wound.
  • FIG. 9 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 10 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG. 9 .
  • FIG. 11 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 12 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • Fig. 13 is an exploded view of the battery pack according to one embodiment of the present application shown in Fig. 11 .
  • FIG. 14 is a schematic diagram of an electrical device in which a secondary battery is used as a power source according to an embodiment of the present application.
  • a "range” disclosed herein is defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Additionally, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5.
  • the numerical range “a to b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0 to 5" means that all real numbers between “0 to 5" have been listed in this article, and "0 to 5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • the inventors found that due to the dense structure and thin thickness of the conductive layer and support layer of the current collector (compared to conventional metal foil current collectors such as aluminum foil or copper foil), the electrical connection members are welded at the edge of the current collector At the transfer welding area, the conductive layer and the support layer are easily welded through. If the slag generated by welding and the particles dropped in the subsequent process fall into the diaphragm area through the welded conductive layer and support layer, Then the battery will produce self-discharge, and even an internal short circuit will occur.
  • the inventors have found that by providing a first insulating layer on the other surface of the current collector that covers at least the entirety of the transfer welding area when viewed from the thickness direction of the pole piece, the first insulating layer prevents The protective effect of slag and particles falling into the diaphragm area can reliably prevent metal welding through during welding and cause short circuit. Therefore, on the one hand, the safety of the secondary battery using the pole piece is increased by preventing internal short circuit, and on the other hand, the DC internal resistance of the secondary battery is reduced by preventing debris from falling into other areas.
  • a pole piece is provided.
  • the pole piece 6 includes a current collector 61 , an active material layer 62 disposed on one surface of the current collector 61 , and an electrical connection member 63 electrically connected to the current collector 61 .
  • the active material layer 62 is provided on one surface of the current collector 61 via an undercoat layer 66 described later, however, the active material layer 62 may be directly provided on one surface of the current collector 61 .
  • the active material layer 62 is disposed on the main body of the current collector 61, and the electrical connection member 63 is welded to the current collector 61 at the edge of the current collector 61.
  • This welded connection area is called a transfer welding area. a.
  • the current collector 61 includes a support layer 611 and a conductive layer 612 disposed on one surface of the support layer 611 .
  • the conductive layer 612 plays the role of electric conduction and current collection, and is used to provide electrons for the active material layer.
  • the material of the conductive layer is selected from at least one of metal conductive materials and carbon-based conductive materials.
  • the above metal conductive material is preferably at least one of aluminum, copper, nickel, titanium, silver and their alloys.
  • the aforementioned carbon-based conductive material is preferably at least one of graphite, acetylene black, graphene, and carbon nanotubes.
  • the material of the conductive layer is preferably a metal conductive material, that is, the conductive layer is preferably a metal conductive layer.
  • the conductive layer is preferably a metal conductive layer.
  • the support layer supports and protects the conductive layer. Since the support layer is generally made of organic polymer materials or polymer composite materials, the density of the support layer is usually lower than that of the conductive layer, so that the gravimetric energy density of the battery can be significantly improved compared with traditional metal current collectors.
  • the pole piece 6 also includes a first insulating layer 64. As shown in FIGS. The whole of welding area A.
  • the present application arranges on the other surface of the current collector the first insulating layer that covers at least the entirety of the transfer welding area when viewed from the thickness direction of the pole piece, thereby soldering and connecting the electrical connection on one surface side of the current collector.
  • the first insulating layer on the other surface of the current collector acts as a protection against debris and particles falling into the diaphragm area, it can also reliably prevent metal welding through during welding and cause short circuit, thereby improving the safety of the secondary battery using the pole piece and reducing the internal resistance of the secondary battery.
  • the support layer 611 is made of an insulating material having a fibrous hole structure. Thereby, the ion permeability of the support layer can be improved, and the electrochemical performance can be effectively improved.
  • the supporting layer 611 is a polyethylene film, a polypropylene film, a polyvinylidene chloride film or a multilayer composite film thereof. Accordingly, by constituting the support layer with a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, it is possible to reliably form a support layer with high ion permeability.
  • the edge E1 of the first insulating layer 64 coincides with the edge E2 of the active material layer 62 .
  • the transfer welding region where the electrical connection member is welded is preferably located outside the edge of the active material layer when viewed from the thickness direction of the pole piece. The edge of the first insulating layer and the edge of the active material layer overlap when viewed from the thickness direction of the pole piece, which can reliably ensure that the first insulation layer covers the entire transfer welding area when viewed from the thickness direction of the pole piece.
  • the first insulating layer 64 is made of resin material and is the same material as the supporting layer 611 . Thereby, the ion permeability of the first insulating layer can be improved, and the electrochemical performance can be effectively improved.
  • the first insulating layer 64 is a polyethylene film, a polypropylene film, a polyvinylidene chloride film or a multilayer composite film thereof.
  • the first insulating layer 64 is an adhesive or resin material.
  • the insulating layer can be easily formed by coating or the like.
  • the binder is not particularly limited, and may include styrene-butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-acetic acid
  • SBR styrene-butadiene rubber
  • CMC carboxymethyl cellulose
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA vinyl ester copolymer
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • the pole piece 6 further includes a second insulating layer 65. As shown in FIGS. Cover at least the whole of transfer welding area A when observed.
  • the second insulating layer can be used to fill the riveting hole caused by the soldering and prevent the slag generated by welding and the particles falling in the subsequent process from falling into the riveting hole, thereby preventing the occurrence of hi-po failure.
  • the second insulating layer 65 is an adhesive or resin material. Accordingly, it is possible to reliably fill the caulking hole caused by the soldering with an adhesive or a resin material.
  • the binder is not particularly limited, and may include styrene-butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-acetic acid
  • SBR styrene-butadiene rubber
  • CMC carboxymethyl cellulose
  • PVDF polyvinylidene fluoride
  • PVDF polytetrafluoroethylene
  • EVA vinyl ester copolymer
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • an undercoat layer 66 is disposed between the active material layer 62 and the current collector 61 .
  • the width in the width direction X of the undercoat layer 66 is 1 mm to 3 mm smaller than the width in the width direction X of the active material layer 62 .
  • the pole piece in this application can be a positive pole piece or a negative pole piece.
  • the current collector and the active material layer therein are the positive current collector and the positive active material layer respectively.
  • the pole piece is a negative pole piece, correspondingly, the current collector and the active material layer therein are the negative pole current collector and the negative pole active material layer respectively.
  • the positive pole piece 6 of the present application is a positive pole piece
  • the positive pole piece includes a positive current collector and a positive active material layer disposed on one surface of the positive current collector.
  • the positive electrode active material layer contains a positive electrode active material.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode active material layer is disposed on any one of the two opposing surfaces of the positive electrode current collector.
  • a composite current collector can be used as the positive electrode current collector.
  • the composite current collector may include a support layer composed of an insulating material having a fibrous pore structure and a conductive layer formed on one surface of the support layer.
  • the composite current collector can be formed by metal materials (for example, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a support layer (for example, polyethylene film, polypropylene film, polyvinylidene chloride vinyl film or their multi-layer composite film).
  • the positive electrode active material may be a positive electrode active material known in the art for batteries.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn At least one of 0.1 O 2 (also abbreviated as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al
  • lithium-containing phosphates with olivine structure may include but not limited to lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), composite material of lithium manganese phosphate and carbon, manganese phosphate At least one of the composite materials of iron lithium, lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • manganese phosphate At least one of the composite materials of iron lithium, lithium iron manganese phosphate and carbon.
  • the positive active material layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive active material layer may optionally further include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative pole piece 6 of the present application is a negative pole piece
  • the negative pole piece includes a negative current collector and a negative active material layer disposed on one surface of the negative current collector.
  • the negative active material layer contains a negative active material.
  • the anode current collector has two opposing surfaces in its own thickness direction, and the anode active material layer is disposed on any one of the two opposing surfaces of the anode current collector.
  • the negative electrode current collector can use a composite current collector.
  • the composite current collector may include a support layer composed of an insulating material having a fibrous pore structure and a conductive layer formed on one surface of the support layer.
  • the composite current collector can be formed on a support layer (for example, polyethylene film, polypropylene film, polyvinylidene chloride, etc.) vinyl film or their multi-layer composite film).
  • the negative electrode active material can be a negative electrode active material known in the art for batteries.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative active material layer may optionally further include a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative active material layer may optionally further include a conductive agent.
  • the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode active material layer may optionally include other additives, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • an electrode assembly is provided.
  • the electrode assembly 52 includes a positive pole piece (the first pole piece) 6, a negative pole piece (the second pole piece) 7, and in order to prevent the short circuit of the positive and negative poles when the electrode assembly is made by the winding process, and can simultaneously A barrier membrane 8 through which ions pass.
  • the positive pole piece is called the first pole piece
  • the negative pole piece is called the second pole piece, but it can also be reversed.
  • the positive pole piece among the positive pole piece and the negative pole piece is the pole piece 6 of the above-mentioned structure of the present application.
  • the negative pole piece in the positive pole piece and the negative pole piece is the pole piece 7 of the traditional structure, but it can also be reversed.
  • the negative electrode tab 7 includes a negative electrode current collector 71 , negative electrode active material layers 72 formed on both surfaces of the negative electrode current collector 71 , and an electrical connection member 73 electrically connected to the negative electrode current collector 71 .
  • the support layer 611 of the positive pole piece 6 and the negative pole piece 7 are arranged in such a manner that they are in close contact.
  • FIG. 6 is a top view of the electrode assembly 52 shown in FIG. 5 after being wound. After the electrode assembly is wound, it is arranged in such a way that the positive electrode active material layer of the positive electrode sheet 6 is in close contact with the separator 8 .
  • the support layer 611 functions as a separator between the positive electrode tab 6 and the negative electrode tab 7 .
  • the negative pole piece 7 and the positive pole piece 6 are separated by a separator 8 .
  • FIG. 7 is a cross-sectional view of an electrode assembly 52A according to an embodiment of the present application.
  • FIG. 8 is a plan view of the electrode assembly 52A shown in FIG. 3 after being wound.
  • the difference between the electrode assembly 52A and the above-mentioned electrode assembly 52 is that the positive pole piece and the negative pole piece are pole pieces with the above-mentioned structure of the present application, respectively.
  • the negative electrode tab 6A includes a current collector 61A, an active material layer 62A provided on one surface of the current collector 61A, and an electrical connection member 63A electrically connected to the current collector 61A.
  • the pole piece 6A further includes a first insulating layer 64A disposed on the other surface of the current collector 61A and covering at least the whole of the transfer welding area A when viewed from the thickness direction Y of the pole piece 6A.
  • the support layer 611 of the positive electrode sheet 6 is arranged in a manner that is in close contact with the negative electrode active material layer 62A of the negative electrode sheet 6A, and the support layer of the negative electrode sheet 6A is 611A is provided in such a manner that it is in close contact with the positive electrode active material layer 62 of the positive electrode sheet 6 . Therefore, there is no need to provide a separator between the positive and negative electrode sheets 6, 6A in this embodiment, and the support layer 611, 611A functions as a separator between the positive and negative electrode sheets 6, 6A.
  • a secondary battery in one embodiment, includes the above-mentioned pole piece of the present application or the above-mentioned electrode assembly of the present application.
  • the secondary battery also includes an electrolyte.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the present application has no specific limitation on the type of electrolyte, which can be selected according to requirements.
  • electrolytes can be liquid, gel or all solid.
  • the electrolyte is an electrolytic solution.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalatephosphate and lithium tetrafluorooxalatephosphate.
  • the solvent may be selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may optionally include additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve high-temperature or low-temperature performance of batteries, and the like.
  • the secondary battery may also include a separator arranged between the positive electrode piece and the negative electrode piece.
  • a separator is provided.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • the positive pole piece, the negative pole piece, and the separator provided as required can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer package.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer package of the secondary battery can be a hard case, such as a hard plastic case, an aluminum case, a steel case, and the like.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft case may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 9 shows a secondary battery 5 having a square structure as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece, and the separator provided as required can form the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the accommodating cavity. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 11 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may also include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a secondary battery, a battery module or a battery pack can be selected according to its use requirements.
  • FIG. 14 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • a support layer with a certain thickness (5000nm) is selected, and a conductive layer with a certain thickness (2000nm) is formed on one surface by means of vacuum evaporation, mechanical rolling or bonding.
  • the first insulating slurry is coated on the other surface, and dried to obtain a first insulating layer.
  • the formation conditions of the vacuum evaporation method are as follows: the support layer that has been cleaned on the surface is placed in a vacuum coating chamber, and the high-purity metal wire in the metal evaporation chamber is melted and evaporated at a high temperature of 1300 ° C to 2000 ° C. The evaporated metal After passing through the cooling system in the vacuum plating chamber, it is finally deposited on the surface of the support layer to form a conductive layer.
  • the formation conditions of the mechanical rolling method are as follows: place the foil of the conductive layer material in a mechanical roll, roll it to a predetermined thickness by applying a pressure of 20t to 40t, and then place it on a surface-cleaned surface. The surface of the supporting layer, and finally put the two in a mechanical roller, and make the two tightly bonded by applying a pressure of 30t to 50t.
  • the formation conditions of the bonding method are as follows: place the foil of the conductive layer material in a mechanical roller, and roll it to a predetermined thickness by applying a pressure of 20t to 40t; The surface is coated with a mixed solution of PVDF and NMP; finally, the above-mentioned conductive layer with a predetermined thickness is bonded to the surface of the support layer and dried at 100°C.
  • the current collector is an Al foil with a thickness of 12 ⁇ m. Similar to the preparation method of the positive electrode sheet above, the positive electrode active material layer slurry is directly coated on the surface of the Al foil current collector, and then the conventional positive electrode sheet is obtained after post-processing. .
  • conductive materials such as conductive carbon black
  • binders such as PVDF or polyacrylic acid, etc.
  • active materials such as NMP or water
  • the primer slurry is uniformly coated on the surface of the composite current collector at a coating speed of 20m/min, and the primer layer is dried with an oven temperature of 70-100°C and a drying time of 5 minutes.
  • Negative pole piece without conductive undercoat
  • Negative electrode active material artificial graphite, conductive agent Super-P, thickener CMC, and binder SBR are added to solvent deionized water in a mass ratio of 96.5:1.0:1.0:1.5 and mixed evenly to make negative electrode active material layer slurry; Extrusion Coating The negative electrode active material layer slurry was coated on one surface of the composite current collector prepared by the above-mentioned method in partitions; after drying at 85° C., the negative electrode active material layer was obtained.
  • the current collectors with various coatings were cold-pressed, then cut, and then dried under vacuum conditions at 110°C for 4 hours, and the tabs were welded to obtain negative electrode sheets.
  • the current collector is a Cu foil with a thickness of 8 ⁇ m. Similar to the preparation method of the above negative electrode sheet, the negative electrode active material layer slurry is directly coated on the surface of the Cu foil current collector, and then the conventional negative electrode sheet is obtained after post-processing .
  • Negative pole piece with conductive undercoat
  • conductive materials such as conductive carbon black
  • binders such as PVDF or polyacrylic acid, etc.
  • active materials such as NMP or water
  • the primer slurry is uniformly coated on the surface of the composite current collector at a coating speed of 20m/min, and the primer layer is dried with an oven temperature of 70-100°C and a drying time of 5 minutes.
  • the positive electrode sheet (compacted density: 3.4g/cm3), the negative electrode sheet (compacted density: 1.6 g/cm3) and the PP/PE/PP separator (select two separators if necessary) , a separator or no separator) are wound together into a bare cell, then placed in the battery case, injected with electrolyte (EC:EMC volume ratio is 3:7, LiPF6 is 1mol/L), and then sealed , chemical formation and other processes to finally obtain a lithium-ion secondary battery (hereinafter referred to as battery).
  • EMC volume ratio 3:7, LiPF6 is 1mol/L
  • the test equipment forces the battery to pass through a large constant DC current (currently generally using a large current of 40A-80A) in a short period of time (generally 2-3 seconds), and the battery at this time is measured The voltage at both ends, and calculate the current internal resistance of the battery according to the formula.
  • the electrode pole piece was basically prepared according to the above-mentioned "2. Preparation of pole piece”, and the second insulating slurry was optionally coated, and the second insulating layer was obtained after drying. Then, according to the above "3. Preparation of the battery", the battery was finally assembled and tested.
  • Examples 1 to 5 with the first insulating layer show a good protective effect in the lap test, and have a protective effect close to that of conventional pole pieces. DC internal resistance.
  • Example 1 In addition, as can be seen from a comparison between Example 1 and Example 6, by further providing a second insulating layer, the DC internal resistance of the secondary battery can be further reduced. From the comparison between Example 7 and Example 8, it can be seen that by further providing an undercoat layer, the DC internal resistance of the secondary battery can be further reduced.
  • Example 3 it can be seen from the comparison between Example 3 and Example 4 that the protection effect in the lap test can be further improved by overlapping the boundaries between the active material layer and the first insulating layer in the X direction.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供了一种极片、电极组件及二次电池。一种极片，包括集流体、设置于集流体的一个表面上的活性材料层、及与集流体电连接的电连接构件，活性材料层设置于集流体的主体部分，电连接构件与集流体在集流体的边缘处焊接连接，该焊接连接区域称为转接焊区域，集流体包括支撑层和设置于支撑层的一个表面上的导电层，其中，极片还包括第一绝缘层，第一绝缘层设置于集流体的另一个表面上并且在从极片的厚度方向观察时至少覆盖转接焊区域的整体。根据本申请，能够提高二次电池的安全性能并降低二次电池的内阻。

Description

极片、电极组件及二次电池 技术领域
本申请涉及电池领域，尤其涉及一种极片、电极组件及二次电池。
背景技术
近年来，二次电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点而广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、消费类电子产品、军事装备、航空航天等多个领域。由于二次电池取得了极大的发展，因此对其能量密度、循环性能和安全性能等也提出了更高的要求。
现有技术中公开了一种集流体，其包括致密支撑层及设置于支撑层的至少一个表面的致密导电层。但是，上述集流体无法通过传统极耳成型结构，可形成沿电池的厚度方向导通的结构，因此，需采用超声波焊接在集流体的边缘转接焊金属极耳。这样，在上述集流体中，存在在将金属极耳焊接至集流体时金属焊穿短路而致使使用该集流体的二次电池安全性较差、以及焊接时金属碎渣落入其他区域而导致二次电池的内阻增加的问题。
发明内容
本申请是鉴于上述技术问题而进行的，其目的在于，提供一种极片、电极组件、二次电池、电池模块、电池包及用电装置，其能够可靠地防止焊接时金属焊穿而导致短路，从而改善了使用该极片的二次电池的安全性并降低了二次电池的内阻。
为了达到上述目的，本申请提供了一种包括设置于集流体的另一个表面上并且在从厚度方向观察时至少覆盖转接焊区域的整体的第一绝缘层的极片、电极组件、二次电池、电池模块、电池包及用电装置。
本申请的第一方面提供了一种极片，包括集流体、设置于所述集流体的一个表面上的活性材料层、及与所述集流体电连接的电连接构件，所述活性材料层设置于所述集流体的主体部分，所述电连接构件与所述集流体在所述集流体的边缘处焊接连接，该焊接连接区域称为转接焊区域，所述集流体包括支撑层和设置于所述支撑层的一个表面上的导电层，其中，所述极片还包括第一绝缘层，所述第一绝缘层设置于所述集流体的另一个表面上并且在从所述极片的厚度方向观察时至少覆盖所述转接焊区域的整体。
由此，本申请通过在集流体的另一个表面上设置在从极片的厚度方向观察时至少覆盖转接焊区域的整体的第一绝缘层，从而在集流体的一个表面侧焊接连接电连接构件和集流体时，即使集流体的导电层和支撑层被焊穿而使焊接产生的碎渣以及后面工序中掉入的颗粒经由被焊穿的导电层和支撑层而落入用于设置活性材料层的膜片区，由于位于集流体的另一个表面上的第一绝缘层起到防止碎渣以及颗粒落入膜片区的保护作用，因而也能够可靠地防止焊接时金属焊穿而导致短路，从而改善了使用该极片的二次电池的安全性并降低二次电池的内阻。
在任意实施方式中，所述支撑层由具有纤维状的孔洞结构的绝缘材料构成。由此，能够提高支撑层的离子通过性，从而能够有效地提高电化学性能。
在任意实施方式中，所述支撑层为聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜。由此，通过由聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜构成支撑层，能够可靠地构成离子通过性高的支撑层。
在任意实施方式中，在从所述极片的厚度方向观察时，所述第一绝缘层的边缘与所述活性材料层的边缘重合。为了防止电连接构件的焊接连接对活性材料层造成不良影响，电连接构件被焊接连接的转接焊区域在从极片的厚度方向观察时优选位于活性材料层的边缘的外侧，因此，通过使第一绝缘层的边缘与活性材料层的边缘在从极片的厚度方向观察时重合，能够可靠地确保第一绝缘层在从极片的厚度方向观 察时覆盖转接焊区域的整体。
在任意实施方式中，所述第一绝缘层由树脂材料构成且与所述支撑层为相同材料。由此，能够提高第一绝缘层的离子通过性，从而能够有效地提高电化学性能。
在任意实施方式中，所述第一绝缘层为聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜，或者，所述第一绝缘层为粘结剂或树脂材料。由此，通过由聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜构成第一绝缘层，能够可靠地构成离子通过性高的第一绝缘层。另外，通过粘结剂或树脂材料形成第一绝缘层，能够通过涂覆等容易地形成绝缘层。
在任意实施方式中，所述极片还包括第二绝缘层，所述第二绝缘层设置于所述电连接构件的一个表面上并且在从所述极片的厚度方向观察时至少覆盖所述转接焊区域的整体。由此，能够利用第二绝缘层填充焊印所造成的铆接孔而防止向铆接孔掉入焊接所产生的碎渣和后面工序中掉入的颗粒，从而能够防止hi-po不良的产生，降低二次电池的直流内阻。
在任意实施方式中，所述第二绝缘层为粘结剂或树脂材料。由此，能够利用粘结剂或树脂材料可靠地填充焊印所造成的铆接孔。
在任意实施方式中，在所述活性材料层和所述集流体之间设置有底涂层；可选地，所述底涂层的宽度比所述活性材料层的宽度小1mm至3mm。通过在活性材料层和集流体之间设置底涂层，可以提高集流体和活性物质之间的粘结力，保证活性材料层更牢固地设置于集流体的表面，而且，底涂层可以改善极片的过流能力和电化学性能。另外，通过底涂层的宽度比活性材料层的宽度小1mm至3mm，从而能够防止电连接构件接触到底涂层而产生焊接不良及虚焊。
本申请的第二方面提供一种电极组件，其中，包括第一极片和第二极片，所述第一极片和所述第二极片中的一个极片为本申请的第一方面所述的极片，以所述第一极片和所述第二极片中的所述一个极片的支撑层与所述第一极片和所述第二极片中的另一个极片紧密接触的方式设置。
本申请的第三方面还提供一种电极组件，其中，包括第一极片和第二极片，所述第一极片和所述第二极片分别为本申请的第一方面所述的极片，以所述第一极片的支撑层与所述第二极片的活性材料层紧密接触的方式设置，并且，以所述第二极片的支撑层与所述第一极片的活性材料层紧密接触的方式设置。
本申请的第四方面提供一种二次电池，其中，所述二次电池包括本申请的第一方面所述的极片或本申请的第二方面或第三方面所述的电极组件。
本申请的第五方面提供一种电池模块，其中，所述电池模块包括本申请的第四方面所述的二次电池。
本申请的第六方面提供一种电池包，其中，所述电池包包括本申请的第五方面所述的电池模块。
本申请的第七方面提供一种用电装置，其中，所述用电装置包括选自本申请的第四方面所述的二次电池、本申请的第五方面所述的电池模块和本申请的第六方面所述的电池包中的至少一种。
根据本申请，能够可靠地防止焊接时金属焊穿而导致短路。
附图说明
图1是本申请一实施方式的极片的截面图。
图2是本申请一实施方式的极片的俯视图。
图3是本申请一实施方式的极片的极耳部分的仰视图。
图4是本申请一实施方式的极片的极耳部分的俯视图。
图5是本申请一实施方式的电极组件的截面图。
图6是图5所示的电极组件卷绕后的俯视图。
图7是本申请一实施方式的电极组件的截面图。
图8是图5所示的电极组件卷绕后的俯视图。
图9是本申请一实施方式的二次电池的示意图。
图10是图9所示的本申请一实施方式的二次电池的分解图。
图11是本申请一实施方式的电池模块的示意图。
图12是本申请一实施方式的电池包的示意图。
图13是图11所示的本申请一实施方式的电池包的分解图。
图14是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53盖板；6极片；61集流体；611支撑层；612导电层；62活性材料层；63电连接构件；64第一绝缘层；65第二绝缘层；66底涂层；7极片；71集流体；72活性材料层；73电连接构件；8隔离膜；52A电极组件；6A极片；61A集流体；611A支撑层；612A导电层；62A活性材料层；63A电连接构件；64A第一绝缘层；65A第二绝缘层；66A底涂层。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的极片、电极组件、二次电池、电池模块、电池包及用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60至120和80至110的范围，理解为60至110和80至120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1至3、1至4、1至5、2至3、2至4和2至5。在本申请中，除非有其他说明，数值范围“a至b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范 围“0至5”表示本文中已经全部列出了“0至5”之间的全部实数，“0至5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
发明人发现，由于集流体的导电层和支撑层为致密结构而厚度较薄(相对于例如铝箔或铜箔的常规金属箔片集流体而言)，因此在集流体的边缘处焊接电连接构件时，在转接焊区域处，导电层和支撑层易被焊穿，如果焊接产生的碎渣以及后面工序中掉入的颗粒经由被焊穿的导电层和支撑层而落入膜片区，则电池会产生自放电，甚至会发生内短路。为了解决该问题，发明人发现，通过在集流体的另一个表面 上设置在从极片的厚度方向观察时至少覆盖转接焊区域的整体的第一绝缘层，从而第一绝缘层起到防止碎渣以及颗粒落入膜片区的保护作用，能够可靠地防止焊接时金属焊穿而导致短路。从而一方面由于防止了内短路而增加了使用该极片的二次电池的安全性，另一方面由于防止碎渣掉入其他区域而降低了二次电池的直流内阻。
另外，以下适当参照附图对本申请的极片、电池组件、二次电池、电池模块、电池包和用电装置进行说明。
[极片]
本申请的一个实施方式中，提供一种极片。如图1所示，极片6包括集流体61、设置于集流体61的一个表面上的活性材料层62、及与集流体61电连接的电连接构件63。在此，活性材料层62经由下述的底涂层66设置于集流体61的一个表面上，但是，活性材料层62也可以直接设置于集流体61的一个表面上。
如图1、图2所示，活性材料层62设置于集流体61的主体部分，电连接构件63与集流体61在集流体61的边缘处焊接连接，该焊接连接区域称为转接焊区域A。
集流体61包括支撑层611和设置于支撑层611的一个表面上的导电层612。相对于传统的金属集流体来说，在本申请的集流体中，导电层612起到导电和集流的作用，用于为活性材料层提供电子。导电层的材料选自金属导电材料、碳基导电材料中的至少一种。上述金属导电材料优选铝、铜、镍、钛、银以及它们的合金中的至少一种。上述碳基导电材料优选石墨、乙炔黑、石墨烯、碳纳米管中的至少一种。导电层的材料优选为金属导电材料，即导电层优选为金属导电层。其中，当集流体为正极集流体时，通常采用铝为导电层的材料；当集流体为负极集流体时，通常采用铜为导电层的材料。在申请的集流体中，支撑层对导电层起到支撑和保护的作用。由于支撑层一般采用有机高分子材料或高分子复合材料，因此支撑层的密度通常小于导电层的密度，从而较传统的金属集流体可显著提升电池的重量能量密度。
极片6还包括第一绝缘层64，如图1、3所示，第一绝缘层64设置于集流体61的另一个表面上并且在从极片6的厚度方向Y观察时至 少覆盖转接焊区域A的整体。
由此，本申请通过在集流体的另一个表面上设置在从极片的厚度方向观察时至少覆盖转接焊区域的整体的第一绝缘层，从而在集流体的一个表面侧焊接连接电连接构件和集流体时，即使集流体的导电层和支撑层被焊穿而使焊接产生的碎渣以及后面工序中掉入的颗粒经由被焊穿的导电层和支撑层而落入用于设置活性材料层的膜片区，由于位于集流体的另一个表面上的第一绝缘层起到防止碎渣以及颗粒落入膜片区的保护作用，因而也能够可靠地防止焊接时金属焊穿而导致短路，从而改善了使用该极片的二次电池的安全性并降低二次电池的内阻。
在一些实施方式中，支撑层611由具有纤维状的孔洞结构的绝缘材料构成。由此，能够提高支撑层的离子通过性，从而能够有效地提高电化学性能。
在一些实施方式中，支撑层611为聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜。由此，通过由聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜构成支撑层，能够可靠地构成离子通过性高的支撑层。
在一些实施方式中，如图1所示，在从极片6的厚度方向Y观察时，第一绝缘层64的边缘E1与活性材料层62的边缘E2重合。为了防止电连接构件的焊接连接对活性材料层造成不良影响，电连接构件被焊接连接的转接焊区域在从极片的厚度方向观察时优选位于活性材料层的边缘的外侧，因此，通过使第一绝缘层的边缘与活性材料层的边缘在从极片的厚度方向观察时重合，能够可靠地确保第一绝缘层在从极片的厚度方向观察时覆盖转接焊区域的整体。
在一些实施方式中，第一绝缘层64由树脂材料构成且与支撑层611为相同材料。由此，能够提高第一绝缘层的离子通过性，从而能够有效地提高电化学性能。
在一些实施方式中，第一绝缘层64为聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜。由此，通过由聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜构成第一绝缘层，能够可靠地构成 离子通过性高的第一绝缘层。在一些实施方式中，第一绝缘层64为粘结剂或树脂材料。由此，能够通过涂覆等容易地形成绝缘层。粘结剂没有特别的限定，可以包括丁苯橡胶(SBR)、水性丙烯酸树脂、羧甲基纤维素(CMC)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
在一些实施方式中，极片6还包括第二绝缘层65，如图1、4所示，第二绝缘层65设置于电连接构件63的一个表面上并且在从极片6的厚度方向Y观察时至少覆盖转接焊区域A的整体。由此，能够利用第二绝缘层填充焊印所造成的铆接孔而防止向铆接孔掉入焊接所产生的碎渣和后面工序中掉入的颗粒，从而能够防止hi-po不良的产生。
在一些实施方式中，第二绝缘层65为粘结剂或树脂材料。由此，能够利用粘结剂或树脂材料可靠地填充焊印所造成的铆接孔。粘结剂没有特别的限定，可以包括丁苯橡胶(SBR)、水性丙烯酸树脂、羧甲基纤维素(CMC)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
在一些实施方式中，在活性材料层62和集流体61之间设置有底涂层66。可选地，底涂层66的宽度方向X上的宽度比活性材料层62的宽度方向X上的宽度小1mm至3mm。通过在活性材料层和集流体之间设置底涂层，可以提高集流体和活性物质之间的粘结力，保证活性材料层更牢固地设置于集流体的表面，而且，底涂层可以改善极片的过流能力和电化学性能。另外，通过底涂层的宽度比活性材料层的宽度小1mm至3mm，从而能够防止电连接构件接触到底涂层而产生焊接不良及虚焊。
显然，本申请中的极片可以是正极极片或负极极片。极片是正极极片时，相应地，其中的集流体和活性材料层分别为正极集流体和正极活性材料层。极片是负极极片时，相应地，其中的集流体和活性材料层分别为负极集流体和负极活性材料层。
在本申请的极片6为正极极片时，正极极片包括正极集流体及设 置于正极集流体的一个表面上的正极活性材料层。正极活性材料层包含正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极活性材料层设置于正极集流体的相对的两个表面中的任意一者上。
在一些实施方式中，正极集流体可采用复合集流体。复合集流体可包括由具有纤维状的孔洞结构的绝缘材料构成的支撑层和形成于支撑层的一个表面上的导电层。复合集流体可通过将金属材料(例如，铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在支撑层(例如，聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极活性材料层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三 元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极活性材料层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
在本申请的极片6为负极极片时，负极极片包括负极集流体及设置于负极集流体的一个表面上的负极活性材料层。负极活性材料层包含负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极活性材料层设置于负极集流体的相对的两个表面中的任意一者上。
在一些实施方式中，负极集流体可采用复合集流体。复合集流体可包括由具有纤维状的孔洞结构的绝缘材料构成的支撑层和形成于支撑层的一个表面上的导电层。复合集流体可通过将金属材料(例如，铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在支撑层(例如，聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极活性材料层还可选地包括粘结剂。所述 粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极活性材料层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极活性材料层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电极组件]
本申请的一个实施方式中，提供一种电极组件。电极组件52包括正极极片(第一极片)6、负极极片(第二极片)7、及为了在由卷绕工艺制成电极组件时起到防止正负极短路的作用、同时可以使离子通过的一个隔离膜8。在本说明书中，将正极极片称为第一极片，将负极极片称为第二极片，但也可以相反。
在一些实施方式中，正极极片和负极极片中的正极极片为本申请的上述结构的极片6。正极极片和负极极片中的负极极片为传统的结构的极片7，但也可以相反。
如图5所示，负极极片7包括负极集流体71、形成于负极集流体71的两个表面上的负极活性材料层72、及与负极集流体71电连接的电连接构件73。从极片的长度方向X看，以正极极片6的支撑层611与负极极片7紧密接触的方式设置。
图6是图5所示的电极组件52卷绕后的俯视图。在电极组件卷绕后，以正极极片6的正极活性材料层与隔离膜8紧密接触的方式设置。
由此，本实施方式的正极极片6和负极极片7之间不需要设置隔离膜，支撑层611作为正极极片6和负极极片7之间的隔离膜而起作用。而负极极片7和正极极片6之间通过隔离膜8进行隔离。
图7是本申请一实施方式的电极组件52A的截面图。图8是图3所示的电极组件52A卷绕后的俯视图。该电极组件52A与上述的电极组件52的不同在于，正极极片和负极极片分别为本申请的上述结构的极片。即，负极极片6A包括集流体61A、设置于集流体61A的一个表面上的活性材料层62A、及与集流体61A电连接的电连接构件63A。在此，活性材料层62A经由底涂层66A设置于集流体61A的一个表面上，但是，活性材料层62A也可以直接设置于集流体61的一个表面上。极片6A还包括第一绝缘层64A，第一绝缘层64A设置于集流体61A的另一个表面上并且在从极片6A的厚度方向Y观察时至少覆盖转接焊区域A的整体。
如图7、8所示，在本实施方式中，以正极极片6的支撑层611与负极极片6A的负极活性材料层62A紧密接触的方式设置，并且，以负极极片6A的支撑层611A与正极极片6的正极活性材料层62紧密接触的方式设置。由此，本实施方式的正负极极片6,6A之间不需要设置隔离膜，支撑层611，611A作为正负极极片6,6A之间的隔离膜而起作用。
此外，上述方式是以卷绕极片的形式作为例子来说明的，但也适用于层叠式的极片。
[二次电池]
本申请的一个实施方式中，提供一种二次电池。二次电池包括本申请的上述的极片或本申请的上述的电极组件。
二次电池还包括电解质。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。
(电解质)
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
(隔离膜)
在一些实施方式中，为了起到防止正负极短路的作用，同时可以使离子通过，二次电池中也可以还包括设置在正极极片和负极极片之间的隔离膜，但是，由于本申请的极片中的支撑层也可以起到作为隔离膜的作用，因此，本申请的二次电池中，在正极极片和负极极片之间由支撑层隔开的情况下，也可以不另外设置隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片和负极极片、以及根据需要设置的隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料 壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图9是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图10，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片和负极极片、以及根据需要设置的隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
[电池模块]
图11是作为一个示例的电池模块4。参照图11，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
[电池包]
图12和图13是作为一个示例的电池包1。参照图12和图13，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池 箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
[用电装置]
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图14是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
各实施例和对比例中的电极极片所用的集流体制备方法如下：
1、集流体的制备：
选取一定厚度(5000nm)的支撑层，在一个表面通过真空蒸镀、机械辊轧或粘结的方式形成一定厚度(2000nm)的导电层。在另一个表面涂覆第一绝缘浆料，并干燥得到第一绝缘层。
其中，
(1)真空蒸镀方式的形成条件如下：将经过表面清洁处理的支撑层置于真空镀室内，以1300℃至2000℃的高温将金属蒸发室内的高纯金属丝熔化蒸发，蒸发后的金属经过真空镀室内的冷却系统，最后沉积于支撑层的表面，形成导电层。
(2)机械辊轧方式的形成条件如下：将导电层材料的箔片置于机械辊中，通过施加20t至40t的压力将其碾压为预定的厚度，然后将其置于经过表面清洁处理的支撑层的表面，最后将两者置于机械辊中，通过施加30t至50t的压力使两者紧密结合。
(3)粘结方式的形成条件如下：将导电层材料的箔片置于机械辊中，通过施加20t至40t的压力将其碾压为预定的厚度；然后在经过表面清洁处理的支撑层的表面涂布PVDF与NMP的混合溶液；最后将上述预定厚度的导电层粘结于支撑层的表面，并于100℃下烘干。
2、极片的制备：
1)不带有导电底涂层的正极极片：
将92wt％正极活性材料(未指明具体材料的情况下，缺省使用NCM333)、5wt％导电剂Super-P(简称“SP”)和3wt％PVDF，以NMP为溶剂，搅拌均匀配成正极活性材料层浆料(某些实施例的活性材料层浆料组成可能有所变化，此时以该实施例中特别注明的为准)，采用挤压涂布将正极活性材料层浆料分区涂布于按照上述方法制备的复合集流体的一个表面；在85℃下烘干后得到正极活性材料层。然后对带有各涂层的集流体进行冷压，然后切割，再在85℃真空条件下烘干4小时，焊接极耳，得到正极极片。
2)常规正极极片：
集流体是厚度为12μm的Al箔片，类似于上面正极极片的制备方法，将正极活性材料层浆料直接涂布到Al箔片集流体的表面上，再经后处理得到常规正极极片。
3)带有导电底涂层的正极极片：
采用一定配比(4：1)的导电材料(如导电炭黑)和粘结剂(如PVDF或聚丙烯酸等)以及可选的活性材料溶于适当的溶剂中(例如NMP或水中)，搅拌均匀配成底涂浆料。
将底涂浆料均匀涂覆于复合集流体的表面上，涂布速度20m/min，并对底涂层进行干燥，烘箱温度为70～100℃，烘干时间为5 min。
待底涂层完全干燥后，再将92wt％正极活性材料、5wt％导电剂Super-P(简称“SP”)和3wt％PVDF，以NMP为溶剂，搅拌均匀配成 正极活性材料层浆料，采用挤压涂布将正极活性材料层浆料分区涂布于底涂层的表面上；在85℃下烘干后得到正极活性材料层，再经后处理得到带有导电底涂层的正极极片。
4)不带有导电底涂层的负极极片：
将负极活性物质人造石墨、导电剂Super-P、增稠剂CMC、粘接剂SBR按质量比96.5:1.0:1.0:1.5加入到溶剂去离子水中混合均匀制成负极活性材料层浆料；采用挤压涂布将负极活性材料层浆料分区涂布于按照上述方法制备的复合集流体的一个表面；在85℃下烘干后得到负极活性材料层。
然后对带有各涂层的集流体进行冷压，然后切割，再在110℃真空条件下烘干4小时，焊接极耳，得到负极极片。
5)常规负极极片：
集流体是厚度为8μm的Cu箔片，类似于上面负极极片的制备方法，将负极活性材料层浆料直接涂布到Cu箔片集流体的表面上，再经后处理得到常规负极极片。
6)带有导电底涂层的负极极片：
采用一定配比(4：1)的导电材料(如导电炭黑)和粘结剂(如PVDF或聚丙烯酸等)以及可选的活性材料溶于适当的溶剂中(例如NMP或水中)，搅拌均匀配成底涂浆料。
将底涂浆料均匀涂覆于复合集流体的表面上，涂布速度20m/min，并对底涂层进行干燥，烘箱温度为70～100℃，烘干时间为5 min。
待底涂层完全干燥后，再将负极活性物质人造石墨、导电剂Super-P、增稠剂CMC、粘接剂SBR按质量比96.5:1.0:1.0:1.5加入到溶剂去离子水中混合均匀制成负极活性材料层浆料；采用挤压涂布将负极活性材料层浆料分区涂布于集流体的底涂层上；在85℃下烘干后得到负极活性材料层，再经后处理得到延伸区带有导电底涂层的负极极片。
3、电池的制备：
通过常规的电池制作工艺，将正极极片(压实密度：3.4g/cm3)、负极极片(压实密度：1.6 g/cm3)和PP/PE/PP隔膜(视需要选择两个隔离膜、一个隔离膜或无隔离膜)一起卷绕成裸电芯，然后置入电池 壳体中，注入电解液(EC:EMC体积比为3:7，LiPF6为1mol/L)，随之进行密封、化成等工序，最终得到锂离子二次电池(以下简称电池)。
5、电池测试方法：
1)极片搭接测试：
采用将上述3中制得的正极极片和负极极片分别与容量2.2Ah、电压4.2V的电池正负极连接，将正极极片直接与负极接触，观察是否有花火出现。同时，选取多种搭接点，每次搭接方式一致，以验证防护效果，观察极片形貌。
2)DCR(直流内阻)的测试方法：
根据物理公式R＝V/I，测试设备让电池在短时间内(一般为2-3秒)强制通过一个很大的恒定直流电流(目前一般使用40A-80A的大电流)，测量此时电池两端的电压，并按公式计算出当前的电池内阻。
6、测试结果和讨论：
6.1第一和第二绝缘层对二次电池安全性和内阻的影响
下面以正极极片为例，说明第一和第二绝缘层对电池性能的影响，尤其是对二次电池的安全性和直流内阻的影响。按照下表1的配方，基本依据前文“2、极片的制备”所述制备电极极片，可选地再涂覆第二绝缘浆料，干燥后得到第二绝缘层。然后，按照前文“3、电池的制备”最后组成电池，进行测试。
表1
Figure PCTCN2022077402-appb-000001
暗斑(静电导致)，黑点(火星导致)
从表1中可知，通过实施例1～5和比较例1、2的对比，具备第一绝缘层的实施例1～5在搭接测试中显现良好的保护效果，并且具有与常规极片接近的直流内阻。
另外，从实施例1和实施例6的对比可知，通过进一步具备第二绝缘层，能够进一步降低二次电池的直流内阻。从实施例7和实施例8的对比可知，通过进一步具备底涂层，能够进一步降低二次电池的直流内阻。
另外，从实施例3和实施例4的对比可知，通过活性材料层与第一绝缘层的边界在X方向上重合，能够进一步提高搭接测试中的保护效果。
另外，从实施例8、11与实施例9、10的对比可知，通过底涂层与活性材料层在X方向上的边界距离设置为1～3mm，能够进一步降低二次电池的直流内阻。
6.2具备有机支撑层的复合集流体对二次电池体积能量密度的影响
下面结合表2说明具备有机支撑层的复合集流体对二次电池的体积能量密度的影响。
[表2]
二次电池 正极极片 负极极片 体积能量密度
实施例1 复合集流体 常规极片 550Wh/L
实施例12 复合集流体 复合集流体 670Wh/L
对比例1 常规极片 常规极片 490Wh/L
从表2可知，与正负极极片均采用常规极片的二次电池相比，采用具备有机支撑层的复合集流体作为一个极片时，能够提高体积能量密度，而采用具备有机支撑层的复合集流体作为两个极片时，能够进一步提高体积能量密度。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。 此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (15)

  1. 一种极片，包括集流体、设置于所述集流体的一个表面上的活性材料层、及与所述集流体电连接的电连接构件，
    所述活性材料层设置于所述集流体的主体部分，所述电连接构件与所述集流体在所述集流体的边缘处焊接连接，该焊接连接区域称为转接焊区域，
    所述集流体包括支撑层和设置于所述支撑层的一个表面上的导电层，
    其中，所述极片还包括第一绝缘层，所述第一绝缘层设置于所述集流体的另一个表面上并且在从所述极片的厚度方向观察时至少覆盖所述转接焊区域的整体。
  2. 根据权利要求1所述的极片，其中，
    所述支撑层由具有纤维状的孔洞结构的绝缘材料构成。
  3. 根据权利要求2所述的极片，其中，
    所述支撑层为聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的多层复合膜。
  4. 根据权利要求1至3中任一项所述的极片，其中，
    在从所述极片的厚度方向观察时，所述第一绝缘层的边缘与所述活性材料层的边缘重合。
  5. 根据权利要求1至3中任一项所述的极片，其中，
    所述第一绝缘层由树脂材料构成且与所述支撑层为相同材料。
  6. 根据权利要求1所述的极片，其中，
    所述第一绝缘层为聚乙烯膜、聚丙烯膜、聚偏氯乙烯膜或它们的 多层复合膜，
    或者，所述第一绝缘层为粘结剂或树脂材料。
  7. 根据权利要求1至6中任一项所述的极片，其中，
    所述极片还包括第二绝缘层，所述第二绝缘层设置于所述电连接构件的一个表面上并且在从所述极片的厚度方向观察时至少覆盖所述转接焊区域的整体。
  8. 根据权利要求7所述的极片，其中，
    所述第二绝缘层为粘结剂或树脂材料。
  9. 根据权利要求1至8中任一项所述的极片，其中，
    在所述活性材料层和所述集流体之间设置有底涂层；
    可选地，所述底涂层的宽度比所述活性材料层的宽度小1mm至3mm。
  10. 一种电极组件，其中，
    包括第一极片和第二极片，
    所述第一极片和所述第二极片中的一个极片为权利要求1至9中任一项所述的极片，
    以所述第一极片和所述第二极片中的所述一个极片的支撑层与所述第一极片和所述第二极片中的另一个极片紧密接触的方式设置。
  11. 一种电极组件，其中，
    包括第一极片和第二极片，
    所述第一极片和所述第二极片分别为权利要求1至9中任一项所述的极片，
    以所述第一极片的支撑层与所述第二极片的活性材料层紧密接触的方式设置，并且，
    以所述第二极片的支撑层与所述第一极片的活性材料层紧密接触 的方式设置。
  12. 一种二次电池，其中，
    所述二次电池包括权利要求1至9中任一项所述的极片或权利要求10或11所述的电极组件。
  13. 一种电池模块，其中，
    所述电池模块包括权利要求12所述的二次电池。
  14. 一种电池包，其中，
    所述电池包包括权利要求13所述的电池模块。
  15. 一种用电装置，其中，
    所述用电装置包括选自权利要求12所述的二次电池、权利要求13所述的电池模块和权利要求14所述的电池包中的至少一种。
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JP2016119183A (ja) * 2014-12-19 2016-06-30 トヨタ自動車株式会社 電極体および正極の製造方法
CN111180664A (zh) * 2019-06-28 2020-05-19 宁德时代新能源科技股份有限公司 一种电极极片和电化学装置
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