WO2021027492A1 - 电极组件和电池单体 - Google Patents

电极组件和电池单体 Download PDF

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Publication number
WO2021027492A1
WO2021027492A1 PCT/CN2020/102832 CN2020102832W WO2021027492A1 WO 2021027492 A1 WO2021027492 A1 WO 2021027492A1 CN 2020102832 W CN2020102832 W CN 2020102832W WO 2021027492 A1 WO2021027492 A1 WO 2021027492A1
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WO
WIPO (PCT)
Prior art keywords
tab
material layer
active material
insulating layer
pole piece
Prior art date
Application number
PCT/CN2020/102832
Other languages
English (en)
French (fr)
Inventor
刘会会
谷慧
曹警予
马林
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.)
Filing date
Publication date
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 CN202090000632.7U priority Critical patent/CN216698661U/zh
Priority to EP20852469.4A priority patent/EP3926753B1/en
Publication of WO2021027492A1 publication Critical patent/WO2021027492A1/zh
Priority to US17/565,873 priority patent/US20220123444A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/533—Electrode connections inside a battery casing characterised by the shape of the leads or tabs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • 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
    • H01M10/04—Construction or manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/547—Terminals characterised by the disposition of the terminals on the cells
    • H01M50/55—Terminals characterised by the disposition of the terminals on the cells on the same side of the cell
    • 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 embodiments of the present application relate to the field of batteries, and in particular to an electrode assembly and battery cells.
  • the secondary battery includes an electrode assembly, a casing and an electrode terminal.
  • the electrode assembly is contained in the casing, and the electrode terminal is arranged in the casing.
  • the electrode assembly includes a first pole piece, a second pole piece and a diaphragm, and the diaphragm separates the first pole piece and the second pole piece.
  • the pole piece of the electrode assembly has tabs, and the tabs are electrically connected to the electrode terminals.
  • the tabs themselves are very thin, the tabs are easily pressed between the first pole piece and the second pole piece, thereby causing a risk of short circuit.
  • various aspects of the present application provide an electrode assembly and a battery cell, which can reduce the risk of short circuit and improve safety performance.
  • the first aspect of the present application provides a battery cell, which includes an electrode assembly, a housing, and a first electrode terminal.
  • the casing has a containing cavity, the electrode assembly is contained in the containing cavity, and the first electrode terminal is arranged in the casing.
  • the electrode assembly includes a first pole piece, a second pole piece and a diaphragm, and the diaphragm separates the first pole piece and the second pole piece.
  • the first pole piece includes a first current collector, a first active material layer and an insulating layer;
  • the first current collector includes a first body portion and a first tab extending from the first body portion, and the surface of the first body portion is at least partially coated Covered with the first active material layer, the first tab protrudes from the first body part and is electrically connected to the first electrode terminal.
  • the insulating layer is at least partially coated on the surface of the first tab, and the elastic modulus of the insulating layer is smaller than the elastic modulus of the first tab.
  • each first tab There are multiple first tabs, and both surfaces of each first tab are partially coated with an insulating layer.
  • the shell includes a shell and a top cover, the shell has an opening, the top cover is connected to the shell and covers the opening of the shell, and the first electrode terminal is arranged on the top cover.
  • the battery cell further includes a first current collecting member, and the first tab is electrically connected to the first electrode terminal through the first current collecting member.
  • the first tab is welded to the first current collecting member and forms a welding zone; the first tab includes a connecting part extending from one end of the first main body part, and the connecting part is connected between the welding zone and the first main body part.
  • the connection part is at least partially coated with an insulating layer.
  • the insulating layer is spaced from the welding area.
  • the ratio of the length of the area coated with the insulating layer of the connecting portion to the total length of the connecting portion is 0.3-0.9.
  • connection part is bent in the area where the insulating layer is not coated.
  • the elastic modulus of the insulating layer is 5 megapascals (Mpa)-60Mpa, and the thickness of the insulating layer is 10 micrometers ( ⁇ m)-60 ⁇ m.
  • the insulating layer includes an inorganic filler and an adhesive, and the weight ratio of the inorganic filler to the adhesive is 4.1-8.2.
  • the swelling rate of the insulating layer is less than 50%.
  • the insulating layer includes a first part and a second part.
  • the first part is coated on the surface of the first body part and connected to an end of the first active material layer close to the first tab.
  • the second part is away from the first active material from the first part
  • One end of the layer extends and is coated on the surface of the first tab.
  • the second pole piece includes a second current collector and a second active material layer
  • the second current collector includes a second main body portion and a second tab extending from the second main body portion.
  • the second active material layer is coated on the surface of the second main body, and the second tab protrudes from the second main body.
  • the end of the second active material layer extends beyond the junction of the first part and the first active material layer, and does not extend beyond the end of the first part away from the first active material layer.
  • the second pole piece also includes a third active material layer, which is coated on the surface of the second tab and connected to the second active material layer.
  • the first tab and the second tab are located on the same side of the electrode assembly. Along the direction of the first main body pointing to the first tab, the end of the third active material layer away from the second active material layer exceeds the end of the first part away from the first active material layer.
  • a second aspect of the present application provides an electrode assembly, including a first pole piece and a second pole piece;
  • the first pole piece includes a first current collector, a first active material layer, and an insulating layer;
  • the first current collector includes a first main body portion and the first tab extending from the first main body portion, the first The surface of a main body is at least partially coated with the first active material layer, and the first tab protrudes from the first main body;
  • the insulating layer is at least partially coated on the surface of the first tab, and the elastic modulus of the insulating layer is smaller than the elastic modulus of the first tab.
  • each first tab there are a plurality of the first tabs, and both surfaces of each first tab are coated with the insulating layer near the root region of the first main body.
  • the elastic modulus of the insulating layer is 5 MPa to 60 MPa, and the thickness of the insulating layer is 10 to 60 microns.
  • the insulating layer includes an inorganic filler and an adhesive, and the weight ratio of the inorganic filler to the adhesive is 4.1-8.2.
  • the swelling rate of the insulating layer is less than 50%.
  • the insulating layer includes a first part and a second part, and the first part is coated on the surface of the first body part and connected to the first active material layer near the first tab. At one end, the second part extends from an end of the first part away from the first active material layer and is coated on the surface of the first tab.
  • the second pole piece includes a second current collector and a second active material layer, and the second current collector includes a second main body portion and a second tab extending from the second main body portion;
  • the second active material layer is coated on the surface of the second main body, and the second tab protrudes from the second main body;
  • the end of the second active material layer extends beyond the junction of the first part and the first active material layer, and does not extend beyond the first tab A part is away from the end of the first active material layer.
  • the second pole piece further includes a third active material layer that is coated on the surface of the second tab and connected to the second active material layer;
  • the first tab and the second tab are located on the same side of the electrode assembly
  • the end of the third active material layer away from the second active material layer extends beyond the first part away from the first active material layer Ends.
  • the insulating layer in the electrode assembly can play a role of insulation and protection. Even if the first tab is inserted between the first pole piece and the second pole piece, the insulating layer can effectively The first pole ear is separated from the second pole piece, thereby reducing the risk of short circuit and improving safety performance. Compared with the first tab, the insulating layer has a smaller elastic modulus. Therefore, during the assembly process of the battery cell, the insulating layer will not interfere with the folding and bending of the first tab, thereby reducing the first tab The occupied space ensures the energy density of the battery cells.
  • Fig. 1 is an exploded view of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is a cross-sectional view of a secondary battery according to another embodiment of the present application.
  • Fig. 3 is an enlarged view of the secondary battery of Fig. 2 at block A.
  • Fig. 4 is a schematic diagram of an electrode assembly of a secondary battery according to another embodiment of the present application.
  • Fig. 5 is a cross-sectional view of the electrode assembly of Fig. 4 taken along the line B-B.
  • Fig. 6 is a cross-sectional view of the electrode assembly of Fig. 4 taken along line C-C.
  • Fig. 7 is an enlarged view of the electrode assembly of Fig. 6 at block D.
  • FIG. 8 is a schematic diagram of the first pole piece of the electrode assembly of FIG. 6 in an unfolded state.
  • Fig. 9 is another schematic diagram of the first pole piece of Fig. 8, wherein the first active material layer and the insulating layer are omitted.
  • Fig. 10 is a schematic diagram of the first pole piece of Fig. 8 before being formed.
  • Fig. 11 is a schematic diagram of the second pole piece of Fig. 6 in an expanded state.
  • Fig. 12 is another schematic diagram of the second pole piece of Fig. 11, in which the second active material layer and the third active material layer are omitted.
  • FIG. 13 is a schematic diagram of the electrode assembly and the first current collecting member according to another embodiment of the present application after being welded.
  • Figure 14 is an enlarged view of Figure 13 at block E.
  • Figure 15 is an enlarged view of Figure 13 at block F.
  • the secondary battery according to an embodiment of the present application includes an electrode assembly 1, a housing 2, a first electrode terminal 3, and a second electrode terminal 5.
  • the electrode assembly 1 is the core component of the secondary battery to realize the charge and discharge function. 4 to 6, the electrode assembly 1 includes a first pole piece 11, a second pole piece 12 and a diaphragm 13, and the diaphragm 13 separates the first pole piece 11 and the second pole piece 12.
  • the electrode assembly 1 may have a wound structure. Specifically, both the first pole piece 11 and the second pole piece 12 are one, and the first pole piece 11 and the second pole piece 12 have a belt-shaped structure. The first pole piece 11, the diaphragm 13, and the second pole piece 12 are sequentially stacked and wound two or more turns to form the electrode assembly 1.
  • the electrode assembly 1 may be flat.
  • the electrode assembly 1 may also have a laminated structure. Specifically, the first pole piece 11 is provided in multiples, and the second pole piece 12 is provided in multiples. The multiple first pole pieces 11 and the second pole pieces 12 are alternately stacked, and the diaphragm 13 connects the first pole pieces 11 and The second pole pieces 12 are separated.
  • the housing 2 has a containing cavity, and the electrode assembly 1 and the electrolyte are contained in the containing cavity.
  • the case 2 is used to protect the electrode assembly 1 from the outside.
  • the secondary battery is a soft pack battery
  • the outer casing 2 may be a packaging bag made of aluminum plastic film.
  • the secondary battery is a hard shell battery.
  • the housing 2 includes a housing 21 and a top cover 22, the housing 21 has an opening, and the top cover 22 is connected to the housing 21 and covers the opening of the housing 21.
  • the housing 21 may have a hexahedral shape or other shapes.
  • An accommodating cavity is formed inside the casing 21 to accommodate the electrode assembly 1 and the electrolyte.
  • the case 21 is formed with an opening at one end, and the electrode assembly 1 can be placed into the receiving cavity of the case 21 through the opening.
  • the housing 21 may be made of a conductive metal material.
  • the housing 21 may be made of aluminum or aluminum alloy.
  • the top cover 22 is disposed on the housing 21 and covers the opening of the housing 21 so as to seal the electrode assembly 1 in the housing 21.
  • the top cover 22 may be a metal plate, and is connected to the housing 21 by welding.
  • the first electrode terminal 3 and the second electrode terminal 5 are provided in the housing 2.
  • the first electrode terminal 3 and the second electrode terminal 5 are provided on the top cover 22 of the case 2.
  • the secondary battery further includes a first current collecting member 4 and a second current collecting member 6.
  • the first pole piece 11 is electrically connected to the first electrode terminal 3 through the first current collecting member 4
  • the second pole piece 12 is electrically connected to the first electrode terminal 3 through the first current collecting member 4.
  • the current collecting member 6 is electrically connected to the second electrode terminal 5.
  • the first pole piece 11 includes a first current collector 111 and a first active material layer 112.
  • the first current collector 111 includes a first main body portion 1111 and a first tab 1112 extending from the first main body portion 1111.
  • the surface of the first body portion 1111 is at least partially coated with the first active material layer 112, and the first tab 1112 protrudes from the first body portion 1111 and is electrically connected to the first electrode terminal 3.
  • the second pole piece 12 includes a second current collector 121 and a second active material layer 122.
  • the second current collector 121 includes a second main body portion 1211 and a second tab 1212 extending from the second main body portion 1211.
  • the second active material layer 122 is coated on the surface of the second body portion 1211, and the second tab 1212 protrudes from the second body portion 1211 and is electrically connected to the second electrode terminal 5.
  • the first pole piece 11 may be a positive pole piece, and the second pole piece 12 may be a negative pole piece.
  • the first current collector 111 is aluminum foil
  • the first active material layer 112 includes a ternary material, lithium manganate or lithium iron phosphate
  • the second current collector 121 is copper foil
  • the second active material layer 122 includes graphite or silicon.
  • the plurality of first tabs 1112 are stacked together and welded to the first current collecting member 4.
  • the unwelded areas of the plurality of first tabs 1112 are in a dispersed state.
  • the first tabs 1112 can be easily assembled during the assembly process of the secondary battery. It is deformed and pressed between the first pole piece 11 and the second pole piece 12, thereby causing a risk of short circuit.
  • an insulating layer 113 is provided in the embodiment of the present application. Specifically, referring to FIGS. 6 to 8, the insulating layer 113 is at least partially coated on the surface of the first tab 1112. The insulating layer 113 can play the role of insulation protection. Even if the first tab 1112 is inserted between the first pole piece 11 and the second pole piece 12, the insulating layer 113 can effectively connect the first tab 1112 with the second pole piece. The sheets 12 are separated, thereby reducing the risk of short circuit and improving safety performance.
  • the first tab 1112 needs to be folded and bent. If the elastic modulus of the insulating layer 113 is large, it will be difficult for the first tab 1112 to bend, causing the first tab 1112 to occupy a larger space and reduce the energy density of the secondary battery. Therefore, optionally, the elastic modulus of the insulating layer 113 is smaller than the elastic modulus of the first tab 1112.
  • the insulating layer 113 has a smaller elastic modulus relative to the first tab 1112. Therefore, during the assembly process of the secondary battery, the insulating layer 113 will not interfere with the folding of the first tab 1112. And bending, thereby reducing the space occupied by the first tab 1112 and ensuring the energy density of the secondary battery.
  • Each first tab 1112 has two opposite surfaces, and each surface of each first tab 1112 is coated with an insulating layer 113. In order to prevent the insulating layer 113 from interfering with the welding of the first tab 1112 and the first current collecting member 4, each surface of each first tab 1112 is coated with an insulating layer 113 in a partial area. The embodiment of the present application can reduce the risk of each first tab 1112 contacting the second tab 12.
  • the root area of the first tab 1112 close to the first main body portion 1111 has the highest risk of bending and deformation. Therefore, the insulating layer 113 covers the first tab 1112 close to the first main body portion 1111. The root area.
  • the insulating layer 113 is connected to the first active material layer 112, which can reduce the risk of the insulating layer 113 falling off.
  • the insulating layer 113 includes a first portion 113a and a second portion 113b, the first portion 113a is coated on the surface of the first body portion 1111 and connected to the first active material layer 112 near the first tab 1112 At one end, the second portion 113b extends from the end of the first portion 113a away from the first active material layer 112 and is coated on the surface of the first tab 1112.
  • the second portion 113b can cover the root region of the first tab 1112 close to the first body portion 1111, and effectively reduce the risk of the root region of the first tab 1112 contacting the second active material layer 122.
  • the insulating layer 113 includes an inorganic filler and an adhesive.
  • Inorganic fillers include boehmite, alumina, magnesium oxide, titanium dioxide, zirconium oxide, silicon dioxide, silicon carbide, boron carbide, calcium carbonate, aluminum silicate, calcium silicate, potassium titanate, barium sulfate or one of Several kinds.
  • the binder includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyacrylic acid, polyacrylate, polyacrylic acid-acrylate, polyacrylonitrile-acrylic acid, and polyacrylonitrile-acrylate.
  • the first pole piece 11 of the embodiment of the present application can be prepared according to the following steps:
  • ternary materials such as LiNi0.5Co0.2Mn0.3O2 (NCM523)), conductive agent acetylene black, and binder (such as polyvinylidene fluoride (PVDF)), and add solvent (For example: N-Methyl pyrrolidone (NMP)), stir under the action of a vacuum stirrer until the system is uniform to obtain a positive electrode slurry.
  • solvent for example: N-Methyl pyrrolidone (NMP)
  • the positive electrode slurry and the insulating slurry are coated on the surface of the aluminum foil, the positive electrode slurry is cured to form the first active material layer 112, and the insulating slurry is cured to form the insulating layer 113.
  • step (iv) a certain distance is maintained between the tool and the first active material layer 112 to prevent the tool from acting on the first active material layer 112 due to process errors and prevent the active material in the first active material layer 112 from falling off .
  • the burr formed on the cutting edge can be effectively reduced, thereby reducing the risk of the burr piercing the diaphragm 13.
  • the lithium ions of the first active material layer 112 pass through the separator 13 and are embedded in the second active material layer 122.
  • the second active material layer 122 needs to have a larger width. Specifically, referring to FIG. 6, both ends of the second active material layer 122 in the height direction Z extend beyond the first active material layer 112.
  • one end of the second active material layer 122 close to the first tab 1112 extends beyond the first active material layer 112 close to the first tab 1112
  • One end of the second active material layer 122 points toward the first body portion 1111 along the first tab 1112, and the other end of the second active material layer 122 away from the first tab 1112 extends beyond the first active material layer 112 away from the first electrode The other end of the ear 1112.
  • the end of the second active material layer 122 is flush with the end of the second body portion 1211.
  • burrs will be generated at the end of the second main body portion 1211, and the burrs may easily pierce the diaphragm 13.
  • the first portion 113a can separate the burr at the end of the second body portion 1211 from the first body portion 1111, thereby reducing the risk of short circuit.
  • the second pole piece 12 further includes a third active material layer 123, and the third active material layer 123 is coated on the surface of the second tab 1212 and connected to the second active material layer 122.
  • the second active material layer 122 and the third active material layer 123 are integrally formed.
  • graphite, conductive agent acetylene black, thickener (such as carboxymethyl cellulose (Carboxymethyl Cellulose, CMC)), binder (such as styrene butadiene rubber (SBR)) can be mixed , Adding solvent deionized water and stirring to form a negative electrode slurry, and then coating the negative electrode slurry on the surface of the second current collector 121.
  • the negative electrode slurry is cured to form a negative electrode active material layer, and then the second tab 1212 is cut out. When cutting, the cutter can directly act on the negative active material layer.
  • the portion of the negative active material layer remaining on the second body portion 1211 is the second active material layer 122, and the portion of the negative active material layer remaining on the second tab 1212 is the third active material Layer 123.
  • Cutting on the negative active material layer can reduce the burrs at the cut and reduce the risk of the separator 13 being punctured.
  • the regions of the plurality of second tabs 1212 where the third active material layer 123 is not coated are gathered and welded to the second current collecting member 6.
  • the third active material layer 123 has a relatively large elastic modulus, which can effectively support the second tab 1212 and reduce the risk of the second tab 1212 being inserted between the first pole piece 11 and the second pole piece 12.
  • the first tab 1112 and the second tab 1212 may be located on the same side of the electrode assembly 1.
  • the end of the third active material layer 123 away from the second active material layer 122 extends beyond the end of the first portion 113a away from the first active material layer 112 In this way, the distance between the area of the second tab 1212 where the third active material layer 123 is not coated and the first active material layer 112 can be increased.
  • the first portion 113a can also play an insulating role, reducing the contact between the second tab 1212 and the first active material layer 112 risks of.
  • the first tab 1112 is electrically connected to the first electrode terminal 3 through the first current collecting member 4. 13 and 14, the first tab 1112 is welded to the first current collecting member 4 and forms a welding area W.
  • the first tab 1112 includes a connecting portion 1112 a extending from one end of the first body portion 1111, and the connecting portion 1112 a is connected between the welding area W and the first body portion 1111.
  • the connecting portion 1112a is at least partially coated with the insulating layer 113.
  • the insulating layer 113 coated on the connecting portion 1112a is the aforementioned second portion 113b.
  • the insulating layer 113 is spaced from the welding area W.
  • the region of the first tab 1112 not coated with the insulating layer 113 is connected between the region of the first tab 1112 coated with the insulating layer 113 and the welding area W. This can prevent the insulating layer 113 from interfering with the welding of the first tab 1112 and the first current collecting member 4.
  • the ratio of the length of the area coated with the insulating layer 113 of the connecting portion 1112a to the total length of the connecting portion 1112a is 0.3-0.9. If the ratio is less than 0.3, the area of the connecting portion 1112a coated with the insulating layer 113 is too short. When the connecting portion 1112a is inserted between the first pole piece 11 and the second pole piece 12, the connecting portion 1112a and the second pole piece 12 The risk of short-circuit contact is still high. If the ratio is greater than 0.9, the distance between the insulating layer 113 and the welding area W is smaller. During welding, the welding area W will generate high temperature.
  • the insulating layer 113 is easily burned out, thereby reducing the connection strength between the insulating layer 113 and the first tab 1112 and affecting the insulating layer 113 The insulation performance.
  • the first tab 1112 usually has a relatively large length, and in order to reduce the space occupied by the first tab 1112, the first tab 1112 may be bent in the embodiment of the present application.
  • the connecting portion 1112 a is bent in a region where the insulating layer 113 is not coated.
  • the area of the connecting portion 1112a uncoated with the insulating layer 113 is bent into two upper and lower layers, the upper layer is substantially parallel to the first current collecting member 4, and the lower layer is bent in a direction close to the first main body portion 1111 relative to the upper layer.
  • the weight ratio of inorganic filler and binder is 4.1-8.2. If the ratio is greater than 8.2, there will be less adhesive, the adhesion between inorganic fillers and the bonding strength between the insulating layer 113 and the first current collector 111 may be insufficient. When in contact with the electrolyte, the insulating layer 113 is easy to fall off; at the same time, if the ratio is greater than 8.2, the elastic modulus of the insulating layer 113 will be too large, and the area of the first tab 1112 coated with the insulating layer 113 is difficult to bend, reducing the energy of the secondary battery density.
  • the ratio is less than 4.1, the insulating effect of the insulating layer 113 is difficult to meet the requirements; furthermore, the inorganic filler in the insulating layer 113 is less, and the first tab 1112 cannot be effectively supported during the winding process of the first pole piece 11 , Causing the risk of the first tab 1112 turning over.
  • the elastic modulus of the insulating layer 113 is 5Mpa-60Mpa, and the thickness of the insulating layer 113 is 10 ⁇ m-60 ⁇ m.
  • the insulating layer 113 may be inserted between the first pole piece 11 and the second pole piece 12 along with the first tab 1112. Under the electrolyte immersion, the insulating layer 113 will expand. If the swelling rate of the insulating layer 113 is too large, the swollen insulating layer 113 will increase the distance between the first active material layer 112 and the second active material layer 122, thereby prolonging the movement path of lithium ions and causing the risk of lithium evolution. In addition, if the swelling rate of the insulating layer 113 is too large, the greater expansion will reduce the adhesive force between the insulating layer 113 and the first tab 1112, which will cause the risk of the insulating layer 113 to fall off and cause insulation failure. Therefore, optionally, the swelling rate of the insulating layer 113 is less than 50%.
  • the secondary battery described above may be referred to as a battery cell.

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Abstract

本申请提供了一种电极组件和电池单体，其中，电池单体包括电极组件、外壳以及第一电极端子。外壳具有容纳腔，电极组件收容于容纳腔，第一电极端子设置于外壳。电极组件包括第一极片、第二极片和隔膜，隔膜将第一极片和第二极片隔开。第一极片包括第一集流体、第一活性物质层以及绝缘层；第一集流体包括第一主体部和从第一主体部延伸的第一极耳，第一主体部的表面至少部分涂覆有第一活性物质层，第一极耳突出于第一主体部并与第一电极端子电连接。绝缘层至少部分涂覆于第一极耳的表面，并且绝缘层的弹性模量小于第一极耳的弹性模量。

Description

电极组件和电池单体
本申请要求于2019年8月14日提交中国专利局、申请号为201910749926.3、发明名称为“二次电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及电池领域，尤其涉及一种电极组件和电池单体。
背景技术
二次电池包括电极组件、外壳和电极端子，电极组件收容于外壳内，电极端子设置于外壳。电极组件包括第一极片、第二极片和隔膜，隔膜将第一极片和第二极片隔开。电极组件的极片具有极耳，极耳与电极端子电连接。但是，在二次电池装配过程中，由于极耳自身很薄，极耳很容易被压入第一极片和第二极片之间，从而引发短路风险。
发明内容
鉴于背景技术中存在的问题，本申请多个方面提供一种电极组件和电池单体，其能降低短路风险，提高安全性能。
本申请的第一方面提供了一种电池单体，其包括电极组件、外壳以及第一电极端子。外壳具有容纳腔，电极组件收容于容纳腔，第一电极端子设置于外壳。电极组件包括第一极片、第二极片和隔膜，隔膜将第一极片和第二极片隔开。第一极片包括第一集流体、第一活性物质层以及绝缘层；第一集流体包括第一主体部和从第一主体部延伸的第一极耳，第一主体部的表面至少部分涂覆有第一活性物质层，第一极耳突出于第一主体部并与第一电极端子电连接。绝缘层至少部分涂覆于第一极耳的表面，并且绝缘层的弹性模量小于第一极耳的弹性模量。
第一极耳为多个，并且每个第一极耳的两个表面均在部分区域涂覆有绝 缘层。
外壳包括壳体和顶盖板，壳体具有开口，顶盖板连接于壳体并覆盖壳体的开口，第一电极端子设置于顶盖板。所述电池单体还包括第一集流构件，第一极耳通过第一集流构件电连接于第一电极端子。第一极耳焊接于第一集流构件并形成焊接区；第一极耳包括从第一主体部的一端延伸的连接部，并且连接部连接于焊接区与第一主体部之间。连接部至少部分涂覆有绝缘层。
沿第一极耳的延伸方向，绝缘层与焊接区间隔设置。
沿第一极耳的延伸方向，连接部的涂覆有绝缘层区域的长度与连接部的总长度之比为0.3～0.9。
连接部在未涂覆绝缘层的区域弯折。
绝缘层的弹性模量为5兆帕(Mpa)-60Mpa，并且绝缘层的厚度为10微米(μm)-60μm。
绝缘层包括无机填料和粘接剂，且无机填料和粘接剂的重量比为4.1-8.2。
绝缘层的溶胀率小于50％。
绝缘层包括第一部分和第二部分，第一部分涂覆于第一主体部的表面且连接于第一活性物质层的靠近第一极耳的一端，第二部分从第一部分的远离第一活性物质层的一端延伸且涂覆于第一极耳的表面。
第二极片包括第二集流体和第二活性物质层，第二集流体包括第二主体部和从第二主体部延伸的第二极耳。第二活性物质层涂覆于第二主体部的表面，第二极耳突出于第二主体部。沿第一主体部指向第一极耳的方向，第二活性物质层的端部超出第一部分和第一活性物质层的连接处，且不超出第一部分远离第一活性物质层的端部。
第二极片还包括第三活性物质层，第三活性物质层涂覆于第二极耳的表面且与第二活性物质层相连。第一极耳和第二极耳位于电极组件的同一侧。沿第一主体部指向第一极耳的方向，第三活性物质层的远离第二活性物质层的端部超出第一部分远离第一活性物质层的端部。
本申请的第二方面提供一种电极组件，包括第一极片和第二极片；
所述第一极片包括第一集流体、第一活性物质层以及绝缘层；所述第一集流体包括第一主体部和所述从第一主体部延伸的第一极耳，所述第一主体部的表面至少部分涂覆有所述第一活性物质层，所述第一极耳突出于第一主体部；
所述绝缘层至少部分涂覆于所述第一极耳的表面，并且所述绝缘层的弹性模量小于所述第一极耳的弹性模量。
可选地，所述第一极耳为多个，并且每个所述第一极耳的两个表面均在靠近所述第一主体部的根部区域涂覆有所述绝缘层。
可选地，所述绝缘层的弹性模量为5兆帕-60兆帕a，并且所述绝缘层的厚度为10微米-60微米。
可选地，所述绝缘层包括无机填料和粘接剂，且无机填料和粘接剂的重量比为4.1-8.2。
可选地，所述绝缘层的溶胀率小于50％。
可选地，所述绝缘层包括第一部分和第二部分，所述第一部分涂覆于所述第一主体部的表面且连接于所述第一活性物质层的靠近所述第一极耳的一端，所述第二部分从所述第一部分的远离所述第一活性物质层的一端延伸且涂覆于所述第一极耳的表面。
可选地，所述第二极片包括第二集流体和第二活性物质层，所述第二集流体包括第二主体部和从所述第二主体部延伸的第二极耳；
所述第二活性物质层涂覆于所述第二主体部的表面，所述第二极耳突出于所述第二主体部；
沿所述第一主体部指向所述第一极耳的方向，所述第二活性物质层的端部超出所述第一部分和所述第一活性物质层的连接处，且不超出所述第一部分远离所述第一活性物质层的端部。
可选地，所述第二极片还包括第三活性物质层，所述第三活性物质层涂覆于所述第二极耳的表面且与所述第二活性物质层相连；
所述第一极耳和所述第二极耳位于所述电极组件的同一侧；
沿所述第一主体部指向所述第一极耳的方向，所述第三活性物质层的远 离所述第二活性物质层的端部超出所述第一部分远离所述第一活性物质层的端部。
上述描述的电极组件和电池单体，电极组件中的绝缘层可以起到绝缘保护的作用，即使第一极耳插入到第一极片和第二极片之间，绝缘层也可以有效地将第一极耳与第二极片隔开，从而降低短路风险，提高安全性能。相对于第一极耳，绝缘层具有较小的弹性模量，因此，在电池单体的装配过程中，绝缘层不会干涉第一极耳的收拢和弯折，从而减小第一极耳占用的空间，保证电池单体的能量密度。
附图说明
图1为根据本申请一实施例的二次电池的分解图。
图2为根据本申请另一实施例的二次电池的剖视图。
图3为图2的二次电池在方框A处的放大图。
图4为根据本申请另一实施例的二次电池的电极组件的示意图。
图5为图4的电极组件沿线B-B作出的剖视图。
图6为图4的电极组件沿线C-C作出的剖视图。
图7为图6的电极组件在方框D处的放大图。
图8为图6的电极组件的第一极片在展开状态的示意图。
图9为图8的第一极片的另一示意图，其中第一活性物质层和绝缘层省略。
图10为图8的第一极片在成型前的示意图。
图11为图6的第二极片在展开状态的示意图。
图12为图11的第二极片的另一示意图，其中第二活性物质层和第三活性物质层省略。
图13为根据本申请另一实施例的电极组件与第一集流构件焊接后的示意图。
图14为图13在方框E处的放大图。
图15为图13在方框F处的放大图。
其中，附图标记说明如下：
1电极组件                2外壳
11第一极片               21壳体
111第一集流体            22顶盖板
1111第一主体部           3第一电极端子
1112第一极耳             4第一集流构件
1112a连接部              5第二电极端子
112第一活性物质层        6第二集流构件
113绝缘层                7焊接保护片
113a第一部分             W焊接区
113b第二部分             X长度方向
12第二极片               Y厚度方向
121第二集流体            Z高度方向
1211第二主体部
1212第二极耳
122第二活性物质层
123第三活性物质层
13隔膜
具体实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本申请，并不用于限定本申请。
在本申请的描述中，除非另有明确的规定和限定，术语“第一”、“第二”、“第三”仅用于描述的目的，而不能理解为指示或暗示相对重要性；术语“多个”是指两个以上(包括两个)；除非另有规定或说明，术语“连接”应做广义理解，例如，“连接”可以是固定连接，也可以是可拆卸连接，或一体地连接，或电连接，或信号连接；“连接”可以是直接相连，也可以通过中间媒介间接相连。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
本说明书的描述中，需要理解的是，本申请实施例所描述的“上”、“下”等方位词是以附图所示的角度来进行描述的，不应理解为对本申请实施例的限定。下面通过具体的实施例并结合附图对本申请做进一步的详细描述。
参照图1和图2，本申请一实施例的二次电池包括电极组件1、外壳2、第一电极端子3以及第二电极端子5。
电极组件1是二次电池实现充放电功能的核心构件。参照图4至图6，电极组件1包括第一极片11、第二极片12和隔膜13，隔膜13将第一极片11和第二极片12隔开。
电极组件1可为卷绕式结构。具体地，第一极片11和第二极片12均为一个，且第一极片11和第二极片12为带状结构。将第一极片11、隔膜13和第二极片12依次层叠并卷绕两圈以上以形成电极组件1。电极组件1可为扁平状。
可替代地，电极组件1也可为叠片式结构。具体地，第一极片11设置为多个，第二极片12设置为多个，所述多个第一极片11和第二极片12交替层叠，隔膜13将第一极片11和第二极片12隔开。
外壳2具有容纳腔，电极组件1和电解液收容于容纳腔。外壳2用于从外侧保护电极组件1。
在一实施例中，所述二次电池为软包电池，外壳2可为由铝塑膜制成的包装袋。
在另一实施例中，所述二次电池为硬壳电池。具体地，外壳2包括壳体21和顶盖板22，壳体21具有开口，顶盖板22连接于壳体21并覆盖壳体21 的开口。壳体21可具有六面体形状或其它形状。壳体21内部形成容纳腔，以收容电极组件1和电解液。壳体21在一端形成开口，而电极组件1可经由所述开口放置到壳体21的容纳腔。壳体21可由导电金属的材料制成，可选地，壳体21由铝或铝合金制成。顶盖板22设置于壳体21并覆盖壳体21的开口，从而将电极组件1密封在壳体21内。顶盖板22可为金属板，且通过焊接的方式连接于壳体21。
第一电极端子3和第二电极端子5设置于外壳2。对于硬壳电池，第一电极端子3和第二电极端子5设置于外壳2的顶盖板22。所述二次电池还包括第一集流构件4和第二集流构件6，第一极片11通过第一集流构件4电连接于第一电极端子3，第二极片12通过第二集流构件6电连接于第二电极端子5。
第一极片11包括第一集流体111和第一活性物质层112，第一集流体111包括第一主体部1111和从第一主体部1111延伸的第一极耳1112。第一主体部1111的表面至少部分涂覆有第一活性物质层112，第一极耳1112突出于第一主体部1111并与第一电极端子3电连接。第一极耳1112设置为多个。
第二极片12包括第二集流体121和第二活性物质层122，第二集流体121包括第二主体部1211和从第二主体部1211延伸的第二极耳1212。第二活性物质层122涂覆于第二主体部1211的表面，第二极耳1212突出于第二主体部1211并与第二电极端子5电连接。第二极耳1212设置为多个。
第一极片11可为正极极片，第二极片12可为负极极片。对应地，第一集流体111为铝箔，第一活性物质层112包括三元材料、锰酸锂或磷酸铁锂；第二集流体121为铜箔，第二活性物质层122包括石墨或硅。
在本申请实施例中，当电极组件1卷绕成型后，多个第一极耳1112层叠在一起，并焊接到第一集流构件4。然而，焊接完成后，多个第一极耳1112的未焊接区域处于分散状态，同时，由于第一极耳1112较薄，因此，在二次电池的装配过程中，第一极耳1112很容易变形并被压入到第一极片11和第二极片12之间，从而引发短路风险。
因此，为了降低短路风险，本申请实施例设置绝缘层113。具体地，参照图6至图8，绝缘层113至少部分涂覆于第一极耳1112的表面。绝缘层113 可以起到绝缘保护的作用，即使第一极耳1112插入到第一极片11和第二极片12之间，绝缘层113也可以有效地将第一极耳1112与第二极片12隔开，从而降低短路风险，提高安全性能。
另外，在二次电池的装配过程中，需要收拢和弯折第一极耳1112。如果绝缘层113的弹性模量较大，那么将会导致第一极耳1112难以弯折，造成第一极耳1112占用较大的空间，降低二次电池的能量密度。因此，可选地，绝缘层113的弹性模量小于第一极耳1112的弹性模量。
在本申请实施例中，相对于第一极耳1112，绝缘层113具有较小的弹性模量，因此，在二次电池的装配过程中，绝缘层113不会干涉第一极耳1112的收拢和弯折，从而减小第一极耳1112占用的空间，保证二次电池的能量密度。
每个第一极耳1112具有两个相对设置的表面，各第一极耳1112的各表面涂覆有绝缘层113。为了避免绝缘层113干涉第一极耳1112与第一集流构件4的焊接，各第一极耳1112的各表面在部分区域涂覆有绝缘层113。本申请实施例可以降低每个第一极耳1112与第二极片12接触的风险。
在二次电池的装配过程中，第一极耳1112的靠近第一主体部1111的根部区域弯折变形的风险最高，因此，绝缘层113覆盖第一极耳1112的靠近第一主体部1111的根部区域。
绝缘层113连接于第一活性物质层112，这样可以降低绝缘层113脱落的风险。
参照图7和图8，绝缘层113包括第一部分113a和第二部分113b，第一部分113a涂覆于第一主体部1111的表面且连接于第一活性物质层112的靠近第一极耳1112的一端，第二部分113b从第一部分113a的远离第一活性物质层112的一端延伸且涂覆于第一极耳1112的表面。第二部分113b可以覆盖第一极耳1112的靠近第一主体部1111的根部区域，并有效地降低第一极耳1112的根部区域与第二活性物质层122接触的风险。
绝缘层113包括无机填料和粘接剂。无机填料包括勃姆石、氧化铝、氧化镁、二氧化钛、氧化锆、二氧化硅、碳化硅、碳化硼、碳酸钙、硅酸铝、硅酸钙、钛酸钾、硫酸钡中的一种或几种。粘结剂包括聚偏氟乙烯、聚丙烯 腈、聚丙烯酸、聚丙烯酸酯、聚丙烯酸-丙烯酸酯、聚丙烯腈-丙烯酸、聚丙烯腈-丙烯酸酯中的一种或几种。
本申请实施例的第一极片11可按照下述步骤制备：
(i)将三元材料(如：LiNi0.5Co0.2Mn0.3O2(NCM523))、导电剂乙炔黑、粘结剂(如：聚偏氟乙烯(Poly vinylidene fluoride，PVDF))进行混合，加入溶剂(如：N-甲基吡咯烷酮(N-Methyl pyrrolidone，NMP))，在真空搅拌机作用下搅拌至体系呈均一状，获得正极浆料。
(ii)将勃姆石和聚偏氟乙烯进行混合，获得绝缘浆料。
(iii)参照图10，将正极浆料和绝缘浆料涂覆在铝箔的表面，正极浆料固化后形成第一活性物质层112，绝缘浆料固化后形成绝缘层113。
(iv)沿着图10的虚线进行裁切并形成第一极耳1112，从而制备出第一极片11。
在步骤(iv)中，刀具与第一活性物质层112之间保持一定的距离，以避免刀具因工艺误差作用在第一活性物质层112上，防止第一活性物质层112中的活性材料脱落。另外，当刀具在绝缘层113上裁切时，可以有效地减小形成于裁切边缘上的毛刺，从而降低毛刺刺破隔膜13的风险。
在电池的使用过程中，第一活性物质层112的锂离子穿过隔膜13并嵌入到第二活性物质层122中。为了保证锂离子能够尽可能地嵌入第二活性物质层122，降低析锂风险，第二活性物质层122需要具有较大的宽度。具体地，参照图6，第二活性物质层122沿高度方向Z的两端均超出第一活性物质层112。换句话说，沿第一主体部1111指向第一极耳1112的方向，第二活性物质层122的靠近第一极耳1112的一个端部超出第一活性物质层112的靠近第一极耳1112的一个端部，沿第一极耳1112指向第一主体部1111的方向，第二活性物质层122的远离第一极耳1112的另一个端部超出第一活性物质层112的远离第一极耳1112的另一个端部。
参照图7，沿第一主体部1111指向第一极耳1112的方向，第二活性物质层122的端部超出第一部分113a和第一活性物质层112的连接处，且不超出第一部分113a远离第一活性物质层112的端部。
参照图12，在高度方向Z上，第二活性物质层122的端部与第二主体部 1211的端部齐平。在第二极片12的成型过程中，第二主体部1211的端部会产生毛刺，毛刺容易刺破隔膜13。在本申请实施例中，第一部分113a可以将第二主体部1211端部的毛刺与第一主体部1111隔开，从而降低短路风险。
第二极片12还包括第三活性物质层123，第三活性物质层123涂覆于第二极耳1212的表面且与第二活性物质层122相连。第二活性物质层122与第三活性物质层123一体成型。
具体地，可将石墨、导电剂乙炔黑、增稠剂(如：羧甲基纤维素(Carboxymethyl Cellulose，CMC))、粘结剂(如：丁苯橡胶(Styrene Butadiene Rubber，SBR))进行混合，加入溶剂去离子水，并通过搅拌形成负极浆料，然后将负极浆料涂覆于第二集流体121的表面。负极浆料固化后形成负极活性物质层，然后裁切出第二极耳1212。裁切时，刀具可直接作用在负极活性物质层上。裁切完成后，负极活性物质层的保留在第二主体部1211上的部分即为第二活性物质层122，负极活性物质层的保留在第二极耳1212上的部分即为第三活性物质层123。在负极活性物质层上裁切，可以减小裁切处的毛刺，降低隔膜13被刺破的风险。
在二次电池的装配过程中，多个第二极耳1212的未涂覆第三活性物质层123的区域收拢并焊接到第二集流构件6。第三活性物质层123具有较大的弹性模量，其能够有效地支撑第二极耳1212，降低第二极耳1212插入到第一极片11和第二极片12之间的风险。
在本申请实施例中，第一极耳1112和第二极耳1212可位于电极组件1的同一侧。可选地，沿第一主体部1111指向第一极耳1112的方向，第三活性物质层123的远离第二活性物质层122的端部超出第一部分113a远离第一活性物质层112的端部，这样可以增大第二极耳1212的未涂覆第三活性物质层123的区域与第一活性物质层112的距离。此时，即使第二极耳1212的未涂覆第三活性物质层123的区域向内弯折，第一部分113a也可以起到绝缘作用，降低第二极耳1212与第一活性物质层112接触的风险。
第一极耳1112通过第一集流构件4电连接于第一电极端子3。参照图13和图14，第一极耳1112焊接于第一集流构件4并形成焊接区W。第一极耳1112包括从第一主体部1111的一端延伸的连接部1112a，并且连接部1112a连接于焊接区W与第一主体部1111之间。
在焊接区W，多个第一极耳1112固定于第一集流构件4，不会出现弯折变形的风险，因此，在焊接区W，第一极耳1112的表面无需设置绝缘层113。另外，在焊接区W设置绝缘层113还会影响第一极耳1112与第一集流构件4的连接强度。因此，在本申请实施例中，连接部1112a至少部分涂覆有绝缘层113。涂覆于连接部1112a的绝缘层113即为前述的第二部分113b。
沿第一极耳1112的延伸方向，绝缘层113与焊接区W间隔设置。换句话说，第一极耳1112的未涂覆绝缘层113的区域连接于第一极耳1112的涂覆有绝缘层113的区域和焊接区W之间。这样可以避免绝缘层113干涉第一极耳1112和第一集流构件4的焊接。
沿第一极耳1112的延伸方向，连接部1112a的涂覆有绝缘层113区域的长度与连接部1112a的总长度之比为0.3～0.9。如果所述比值小于0.3，那么连接部1112a的涂覆有绝缘层113区域过短，当连接部1112a插入第一极片11和第二极片12之间时，连接部1112a与第二极片12短路接触的风险仍然较高。如果所述比值大于0.9，那么绝缘层113与焊接区W的间距较小。焊接时，焊接区W会产生高温，如果绝缘层113与焊接区W的间距过小，绝缘层113容易被烧坏，从而降低绝缘层113和第一极耳1112的连接强度，影响绝缘层113的绝缘性能。
第一极耳1112通常具有较大的长度，而为了减少第一极耳1112占用的空间，本申请实施例可以弯折第一极耳1112。可选地，参照图14，连接部1112a在未涂覆绝缘层113的区域弯折。连接部1112a的未涂覆绝缘层113的区域弯折为上下两层，上层大体平行于第一集流构件4，下层相对于上层朝靠近第一主体部1111的方向弯折。
在连接部1112a的未涂覆绝缘层113的区域进行弯折，可以有效地降低弯折的难度，简化装配工艺。另外，如果在连接部1112a的涂覆有绝缘层113的区域进行弯折，那么绝缘层113的厚度会在高度方向Z上叠加，导致绝缘层113在高度方向Z上占用更多的空间，降低二次电池的能量密度。
无机填料和粘接剂的重量比为4.1-8.2。如果所述比值大于8.2，那么粘接剂较少，无机填料之间的粘着性以及绝缘层113与第一集流体111之间的粘接强度可能会不足，当与电解液接触时，绝缘层113容易脱落；同时，如果所述比值大于8.2，还会导致绝缘层113的弹性模量过大，第一极耳1112的 涂覆有绝缘层113的区域难以弯折，降低二次电池的能量密度。如果所述比值小于4.1，绝缘层113的绝缘效果难以满足要求；再者，绝缘层113中的无机填料较少，在第一极片11的卷绕过程中无法有效地支撑第一极耳1112，引发第一极耳1112翻折的风险。
绝缘层113的弹性模量越大，其越难弯折；如果绝缘层113的弹性模量过大，将会导致第一极耳1112的涂覆有绝缘层113的区域难以弯折。绝缘层113的弹性模量越小，其强度越低；如果绝缘层113的弹性模量过小，那么绝缘层113很容易被二次电池中的杂质刺破，导致绝缘失效。
同样地，绝缘层113的厚度越大，其强度越高，越难以弯折。如果绝缘层113的厚度过大，将会导致第一极耳1112的涂覆有绝缘层113的区域难以弯折，同时还会造成绝缘层113占用过多的空间，降低二次电池的能量密度。绝缘层113的厚度越小，其强度越低；如果绝缘层113的厚度过小，那么绝缘层113很容易被二次电池中的杂质刺破，导致绝缘失效。
因此，综合考虑绝缘层113的弹性模量和厚度，可选地，绝缘层113的弹性模量为5Mpa-60Mpa，绝缘层113的厚度为10μm-60μm。
在二次电池的装配过程中，绝缘层113可能会随着第一极耳1112插入到第一极片11和第二极片12之间。而在电解液的浸泡下，绝缘层113会出现膨胀。如果绝缘层113的溶胀率过大，那么膨胀的绝缘层113会增大第一活性物质层112和第二活性物质层122之间的间距，从而延长锂离子的运动路径，引发析锂风险。另外，如果绝缘层113的溶胀率过大，那么较大的膨胀会降低绝缘层113与第一极耳1112之间的粘接力，从而引发绝缘层113脱落的风险，造成绝缘失效。因此，可选地，绝缘层113的溶胀率小于50％。
本申请的另一实施例，上述描述的二次电池可以称为电池单体。

Claims (20)

  1. 一种电池单体，其特征在于，包括电极组件(1)、外壳(2)以及第一电极端子(3)；
    所述外壳(2)具有容纳腔，所述电极组件(1)收容于所述容纳腔，所述第一电极端子(3)设置于所述外壳(2)；
    所述电极组件(1)包括第一极片(11)和第二极片(12)；
    所述第一极片(11)包括第一集流体(111)、第一活性物质层(112)以及绝缘层(113)；所述第一集流体(111)包括第一主体部(1111)和所述从第一主体部(1111)延伸的第一极耳(1112)，所述第一主体部(1111)的表面至少部分涂覆有所述第一活性物质层(112)，所述第一极耳(1112)突出于所述第一主体部(1111)并与所述第一电极端子(3)电连接；
    所述绝缘层(113)至少部分涂覆于所述第一极耳(1112)的表面，并且所述绝缘层(113)的弹性模量小于所述第一极耳(1112)的弹性模量。
  2. 根据权利要求1所述的电池单体，其特征在于，所述第一极耳(1112)为多个，并且每个所述第一极耳(1112)的两个表面均在靠近所述第一主体部(1111)的根部区域涂覆有所述绝缘层(113)。
  3. 根据权利要求1或2所述的电池单体，其特征在于，
    所述外壳(2)包括壳体(21)和顶盖板(22)，所述壳体(21)具有开口，所述顶盖板(22)连接于所述壳体(21)并覆盖所述壳体(21)的开口，所述第一电极端子(3)设置于所述顶盖板(22)；
    所述电池单体还包括第一集流构件(4)，所述第一极耳(1112)通过所述第一集流构件(4)电连接于所述第一电极端子(3)；
    所述第一极耳(1112)焊接于所述第一集流构件(4)并形成焊接区(W)；所述第一极耳(1112)包括从所述第一主体部(1111)的一端延伸的连接部(1112a)，并且所述连接部(1112a)连接于所述焊接区(W)与所述第一 主体部(1111)之间；
    所述连接部(1112a)至少部分涂覆有所述绝缘层(113)。
  4. 根据权利要求3所述的电池单体，其特征在于，沿所述第一极耳(1112)的延伸方向，所述绝缘层(113)与所述焊接区(W)间隔设置。
  5. 根据权利要求4所述的电池单体，其特征在于，沿所述第一极耳(1112)的延伸方向，所述连接部(1112a)的涂覆有所述绝缘层(113)区域的长度与所述连接部(1112a)的总长度之比为0.3～0.9。
  6. 根据权利要求3-5中任一项所述的电池单体，其特征在于，所述连接部(1112a)在未涂覆所述绝缘层(113)的区域弯折。
  7. 根据权利要求1-6中任一项所述的电池单体，其特征在于，所述绝缘层(113)的弹性模量为5兆帕-60兆帕a，并且所述绝缘层(113)的厚度为10微米-60微米。
  8. 根据权利要求1-7中任一项所述的电池单体，其特征在于，所述绝缘层(113)包括无机填料和粘接剂，且无机填料和粘接剂的重量比为4.1-8.2。
  9. 根据权利要求1-8中任一项所述的电池单体，其特征在于，所述绝缘层(113)的溶胀率小于50％。
  10. 根据权利要求1-9中任一项所述的电池单体，其特征在于，
    所述绝缘层(113)包括第一部分(113a)和第二部分(113b)，所述第一部分(113a)涂覆于所述第一主体部(1111)的表面且连接于所述第一活 性物质层(112)的靠近所述第一极耳(1112)的一端，所述第二部分(113b)从所述第一部分(113a)的远离所述第一活性物质层(111b)的一端延伸且涂覆于所述第一极耳(1112)的表面。
  11. 根据权利要求10所述的电池单体，其特征在于，
    所述第二极片(12)包括第二集流体(121)和第二活性物质层(122)，所述第二集流体(121)包括第二主体部(1211)和从所述第二主体部(1211)延伸的第二极耳(1212)；
    所述第二活性物质层(122)涂覆于所述第二主体部(1211)的表面，所述第二极耳(1212)突出于所述第二主体部(1211)；
    沿所述第一主体部(1111)指向所述第一极耳(1112)的方向，所述第二活性物质层(122)的端部超出所述第一部分(113a)和所述第一活性物质层(112)的连接处，且不超出所述第一部分(113a)远离所述第一活性物质层(111b)的端部。
  12. 根据权利要求11所述的电池单体，其特征在于，
    所述第二极片(12)还包括第三活性物质层(123)，所述第三活性物质层(123)涂覆于所述第二极耳(1212)的表面且与所述第二活性物质层(122)相连；
    所述第一极耳(1112)和所述第二极耳(1212)位于所述电极组件(1)的同一侧；
    沿所述第一主体部(1111)指向所述第一极耳(1112)的方向，所述第三活性物质层(123)的远离所述第二活性物质层(122)的端部超出所述第一部分(113a)远离所述第一活性物质层(111b)的端部。
  13. 一种电极组件(1)，其特征在于，包括第一极片(11)和第二极片(12)；
    所述第一极片(11)包括第一集流体(111)、第一活性物质层(112)以及绝缘层(113)；所述第一集流体(111)包括第一主体部(1111)和所述从第一主体部(1111)延伸的第一极耳(1112)，所述第一主体部(1111)的表面至少部分涂覆有所述第一活性物质层(112)，所述第一极耳(1112)突出于第一主体部；
    所述绝缘层(113)至少部分涂覆于所述第一极耳(1112)的表面，并且所述绝缘层(113)的弹性模量小于所述第一极耳(1112)的弹性模量。
  14. 根据权利要求13所述的电极组件，其特征在于，所述第一极耳(1112)为多个，并且每个所述第一极耳(1112)的两个表面均在靠近所述第一主体部(1111)的根部区域涂覆有所述绝缘层(113)。
  15. 根据权利要求13或14所述的电极组件，其特征在于，所述绝缘层(113)的弹性模量为5兆帕-60兆帕a，并且所述绝缘层(113)的厚度为10微米-60微米。
  16. 根据权利要求13-15中任一项所述的电极组件，其特征在于，所述绝缘层(113)包括无机填料和粘接剂，且无机填料和粘接剂的重量比为4.1-8.2。
  17. 根据权利要求13-16中任一项所述的电极组件，其特征在于，所述绝缘层(113)的溶胀率小于50％。
  18. 根据权利要求13-17中任一项所述的电极组件，其特征在于，
    所述绝缘层(113)包括第一部分(113a)和第二部分(113b)，所述第一部分(113a)涂覆于所述第一主体部(1111)的表面且连接于所述第一活性物质层(112)的靠近所述第一极耳(1112)的一端，所述第二部分(113b) 从所述第一部分(113a)的远离所述第一活性物质层(111b)的一端延伸且涂覆于所述第一极耳(1112)的表面。
  19. 根据权利要求18所述的电极组件，其特征在于，
    所述第二极片(12)包括第二集流体(121)和第二活性物质层(122)，所述第二集流体(121)包括第二主体部(1211)和从所述第二主体部(1211)延伸的第二极耳(1212)；
    所述第二活性物质层(122)涂覆于所述第二主体部(1211)的表面，所述第二极耳(1212)突出于所述第二主体部(1211)；
    沿所述第一主体部(1111)指向所述第一极耳(1112)的方向，所述第二活性物质层(122)的端部超出所述第一部分(113a)和所述第一活性物质层(112)的连接处，且不超出所述第一部分(113a)远离所述第一活性物质层(111b)的端部。
  20. 根据权利要求19所述的电极组件，其特征在于，
    所述第二极片(12)还包括第三活性物质层(123)，所述第三活性物质层(123)涂覆于所述第二极耳(1212)的表面且与所述第二活性物质层(122)相连；
    所述第一极耳(1112)和所述第二极耳(1212)位于所述电极组件(1)的同一侧；
    沿所述第一主体部(1111)指向所述第一极耳(1112)的方向，所述第三活性物质层(123)的远离所述第二活性物质层(122)的端部超出所述第一部分(113a)远离所述第一活性物质层(111b)的端部。
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