WO2021027490A1 - 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
WO2021027490A1
WO2021027490A1 PCT/CN2020/102829 CN2020102829W WO2021027490A1 WO 2021027490 A1 WO2021027490 A1 WO 2021027490A1 CN 2020102829 W CN2020102829 W CN 2020102829W WO 2021027490 A1 WO2021027490 A1 WO 2021027490A1
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WIPO (PCT)
Prior art keywords
active material
material layer
tab
pole piece
electrode assembly
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PCT/CN2020/102829
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English (en)
French (fr)
Inventor
许虎
任苗苗
林永寿
许龙
来佑磊
金海族
朱凌波
Original Assignee
宁德时代新能源科技股份有限公司
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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 EP20851621.1A priority Critical patent/EP3985763B1/en
Publication of WO2021027490A1 publication Critical patent/WO2021027490A1/zh
Priority to US17/665,953 priority patent/US20220158197A1/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
    • H01M4/64—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
    • 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
    • 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
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/19—Sealing members characterised by the material
    • H01M50/195—Composite material consisting of a mixture of organic and inorganic materials
    • 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
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/19—Sealing members characterised by the material
    • H01M50/198—Sealing members characterised by the material characterised by physical properties, e.g. adhesiveness or hardness
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • 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 electrode assembly of the secondary battery includes a pole piece and a separator, and the pole piece includes a current collector and an active material layer coated on the surface of the current collector.
  • the current collector has a coated area coated with an active material layer and an uncoated area not coated with the active material layer, and the tabs are formed by cutting the uncoated area. In the process of cutting the tabs, the cutter can easily act on the active material layer, causing the risk of the active material layer to fall off, resulting in waste of materials.
  • various aspects of the present application provide an electrode assembly and a battery cell.
  • a first 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 and a first active material layer, and the first current collector includes a first body part and a second electrode.
  • a tab, and the first tab extends from one end of the first main body in the longitudinal direction.
  • the first body portion includes a first coating area and a first transition area, the first transition area is disposed between the first tab and the first coating area; the first active material layer is coated on the surface of the first coating area , The first transition zone and the first tab are not coated with the first active material layer.
  • the second pole piece includes a second current collector and a second active material layer.
  • the second current collector includes a second main body and a second tab.
  • the second tab extends from one end of the second main body in the longitudinal direction.
  • the layer is coated on the surface of the second body part.
  • the edge of the first transition area away from the first coating area does not extend beyond the edge of the second active material layer.
  • the first pole piece is a positive pole piece
  • the second pole piece is a negative pole piece, and is directed to the direction of the first tab along the first main body, and the edge of the second active material layer extends beyond the edge of the first active material layer. edge.
  • the edge of the first transition zone exceeds the edge of the first active material layer by at least 0.5 millimeters (mm).
  • the first pole piece further includes an insulating layer, and the insulating layer is at least partially coated on the surface of the first transition region.
  • the insulating layer includes a first part and a second part, the first part is coated on the surface of the first transition zone, and the second part extends from the first part and is coated on the surface of the first tab.
  • the edge of the second part away from the first part extends beyond the edge of the second active material layer.
  • the edge of the second part away from the first part exceeds the edge of the second active material layer by 0.3mm-14mm.
  • the hardness of the insulating layer is greater than the hardness of the first current collector.
  • the insulating layer includes an inorganic filler and a binder, and the weight ratio of the inorganic filler to the binder is 0.4-6.5.
  • the first tab and the second tab are located on the same side of the electrode assembly along the longitudinal direction.
  • the second active material layer includes a base region and a thinned region extending from the base region, and the thickness of the thinned region is smaller than the thickness of the base region.
  • the thinned area is connected to the side of the base area close to the second tab.
  • the second pole piece further includes a third active material layer, which is coated on the surface of the second tab and connected to the thinned area.
  • the size of the third active material layer is larger than the size of the thinned area.
  • the second body portion includes a second coating zone and a second transition zone, and the second transition zone is disposed between the second tab and the second coating zone.
  • the second active material layer is coated on the surface of the second coating area, and the second transition area is not coated with the second active material layer.
  • the electrode assembly further includes a diaphragm, and the diaphragm is used to separate the first pole piece from the second pole piece.
  • a second aspect of the present application provides a battery cell including the electrode assembly described above.
  • the first transition zone is provided on the current collector in the electrode assembly, which can prevent the first active material layer from falling off during the cutting of the first tab.
  • the first transition zone can also reduce the force transmitted to the first active material layer when the battery cell vibrates, reducing the risk of the first active material layer falling off.
  • it can also reduce the overlapping area of the first transition zone and the second active material layer, reduce the probability of impurities falling between the two, and reduce the risk of contact and short circuit between the two.
  • Fig. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • Fig. 2 is a schematic diagram of a first embodiment of an electrode assembly according to the present application.
  • Fig. 3 is a cross-sectional view of the electrode assembly of Fig. 2 taken along the line A-A.
  • Fig. 4 is a cross-sectional view of the electrode assembly of Fig. 2 taken along the line B-B.
  • Fig. 5 is an enlarged view of the electrode assembly of Fig. 4 at block C.
  • Fig. 6 is an enlarged view of the electrode assembly of Fig. 4 at block D.
  • Fig. 7 is a schematic diagram of the first pole piece of Fig. 4 in an expanded state.
  • FIG. 8 is a schematic diagram of the first current collector of the first pole piece of FIG. 7.
  • FIG. 9 is a schematic diagram of the first pole piece of FIG. 7 during the forming process.
  • Fig. 10 is a schematic diagram of the second pole piece of Fig. 4 in an expanded state.
  • FIG. 11 is a schematic diagram of a second current collector of the second pole piece of FIG. 10.
  • Fig. 12 is a schematic diagram of a second embodiment of an electrode assembly according to the present application.
  • Fig. 13 is a cross-sectional view of the electrode assembly of Fig. 12 taken along the line E-E.
  • Fig. 14 is an enlarged view of the electrode assembly of Fig. 13 at block F.
  • Fig. 15 is a schematic diagram of the second pole piece of Fig. 13 in an expanded state.
  • Fig. 16 is a schematic diagram of a third embodiment of an electrode assembly according to the present application.
  • Fig. 17 is an enlarged view of the electrode assembly of Fig. 16 at block G.
  • Fig. 18 is a schematic diagram of the second pole piece of Fig. 16 in an expanded state.
  • the secondary battery according to an embodiment of the present application includes an electrode assembly 4, a case 5, a top cover plate 6, an electrode terminal 7 and a current collecting member 8.
  • the electrode assembly 4 is a core component of the secondary battery to realize the charge and discharge function. 2 and 3, the electrode assembly 4 includes a first pole piece 1, a second pole piece 2 and a diaphragm 3, and the diaphragm 3 separates the first pole piece 1 and the second pole piece 2.
  • the electrode assembly 4 may have a wound structure. Specifically, the first pole piece 1 and the second pole piece 2 are both one, and the first pole piece 1 and the second pole piece 2 have a belt-shaped structure. The first pole piece 1, the diaphragm 3, and the second pole piece 2 are sequentially stacked and wound two or more turns to form the electrode assembly 4. The electrode assembly 4 may be flat.
  • the electrode assembly 4 may also have a laminated structure.
  • the first pole piece 1 is provided in multiples
  • the second pole piece 2 is provided in multiples.
  • the multiple first pole pieces 1 and the second pole pieces 2 are alternately stacked, and the diaphragm 3 connects the first pole pieces 1 and The second pole pieces 2 are separated.
  • the housing 5 may have a hexahedral shape or other shapes.
  • a receiving cavity is formed inside the casing 5 to contain the electrode assembly 4 and the electrolyte.
  • the housing 5 has an opening at one end, and the electrode assembly 4 can be placed into the receiving cavity of the housing 5 through the opening.
  • the housing 5 may be made of conductive metal material.
  • the housing 5 may be made of aluminum or aluminum alloy.
  • the top cover 6 is disposed on the casing 5 and covers the opening of the casing 5 so as to seal the electrode assembly 4 in the casing 5.
  • the top cover 6 may be a metal plate, and is connected to the housing 5 by welding.
  • Two electrode terminals 7 are provided on the top cover 6.
  • the electrode assembly of the present application will be described below with different embodiments.
  • the first pole piece 1 includes a first current collector 11 and a first active material layer 12, and the first current collector 11 includes a first body portion 111 and a first tab 112 , The first tab 112 extends from one end of the first body portion 111 in the longitudinal direction X.
  • the first active material layer 12 is coated on the surface of the first body portion 111.
  • the first pole piece 1 may be a positive pole piece.
  • the first current collector 11 is an aluminum foil, and the first active material layer 12 includes a ternary material, lithium manganate or lithium iron phosphate. There may be multiple first tabs 112. After the first pole piece 1 is wound and formed, a plurality of first pole tabs 112 are stacked together and welded to the current collecting member 8.
  • the second pole piece 2 includes a second current collector 21 and a second active material layer 22.
  • the second current collector 21 includes a second body part 211 and a second tab 212.
  • the second tab 212 extends from the second body part 211 in the longitudinal direction. One end of X extends, and the second active material layer 22 is coated on the surface of the second body portion 211.
  • the second pole piece 2 may be a negative pole piece.
  • the second current collector 21 is a copper foil, and the second active material layer 22 includes graphite or silicon.
  • the first tab 112 and the second tab 212 are located on both sides of the electrode assembly 4 along the longitudinal direction X, respectively.
  • lithium ions in the first active material layer 12 pass through the separator 3 and are embedded in the second active material layer 22.
  • the second active material layer 22 needs to have a larger width. Specifically, both ends of the second active material layer 22 in the longitudinal direction X extend beyond the first active material layer 12.
  • one edge T2 of the second active material layer 22 close to the first tab 112 extends beyond the first active material layer 12 close to the first tab 112
  • the other edge of the second active material layer 22 away from the first tab 112 extends beyond the first active material layer 12 away from the first tab 112 On the other edge.
  • the cutting is performed along the edge of the first active material layer 12, the tool is likely to act on the first active material layer 12 due to process errors, causing the active material in the first active material layer 12 to fall off, resulting in waste of materials. Relatively speaking, the active material in the first active material layer 12 is relatively expensive. Therefore, cutting along the edge of the first active material layer 12 will result in a high cost of the first pole piece 1.
  • the embodiment of the present application increases the size of the first body portion 111 in the longitudinal direction X to increase the distance between the first active material layer 12 and the first tab 112 in the longitudinal direction X .
  • the first body portion 111 includes a first coating area 111a and a first transition area 111b, and the first transition area 111b is disposed between the first tab 112 and the first coating area 111a;
  • the first active material layer 12 is coated on the surface of the first coating region 111 a, and the first transition region 111 b and the first tab 112 are not coated with the first active material layer 12.
  • the dashed line in FIG. 9 shows the movement trajectory of the tool in the process of cutting the first tab 112.
  • a certain distance is maintained between the tool and the first active material layer 12 to prevent the tool from acting on the first active material layer 12 due to process errors and prevent the first active material layer 12
  • the active material falls off.
  • a first transition region 111 b without the first active material layer 12 is formed on the first body portion 111.
  • the current collecting member 8 When the secondary battery vibrates, the current collecting member 8 will pull the first main body 111 through the first tab 112. If there is no first transition zone 111b, stress concentration will occur at the root of the first tab 112, and the portion of the first active material layer 12 close to the root of the first tab 112 is likely to fall off. However, by providing the first transition zone 111b in the embodiment of the present application, the force transmitted to the first active material layer 12 can be reduced, and the risk of the active material in the first active material layer 12 falling off can be reduced.
  • the first pole piece 1 and the second pole piece 2 are laminated together.
  • the surface of the first coating area 111a is coated with the first active material layer 12. Therefore, the gap between the first coating area 111a and the second active material layer 22 of the second pole piece 2 is small; and the first transition The region 111b is not coated with the first active material layer 12, so the gap between the first transition region 111b and the second active material layer 22 of the second pole piece 2 is relatively large.
  • Impurities are generated during the welding process of the first tab 112 and the current collecting member 8. Since the gap between the first transition region 111b and the second active material layer 22 is large, the impurities are easily Fall into the gap. During the charging and discharging process, the first pole piece 1 and the second pole piece 2 will expand, and the impurities falling in the gap may be squeezed during the expansion, so that the impurities pierce the diaphragm 3 and cause a short circuit risk.
  • the edge T1 of the first coating region 111a that is far away from the first transition region 111b does not exceed the edge of the second active material layer 22 T2.
  • This can reduce the overlapping area of the first transition region 111b and the second active material layer 22, thereby reducing the risk of contact and short circuit between the two.
  • the embodiment of the present application also reduces the size of the gap between the first transition region 111b and the second active material layer 22 along the longitudinal direction X, thereby reducing the risk of impurities falling into the gap.
  • the edge T1 of the first transition region 111b shrinks into the second active material layer 22, thereby reducing the risk of the edge T1 adsorbing impurities.
  • burrs will be generated on the edge T1 of the first transition region 111b away from the first coating region 111a, and the burrs will easily pierce the diaphragm 3.
  • lithium ions in the first active material layer 12 pass through the separator 3 and are embedded in the second active material layer 22. If the burr on the edge T1 of the first transition zone 111b is in contact with the lithium intercalation area of the second active material layer 22, a large amount of heat will be generated instantaneously, which will cause an explosion risk. However, if the burr on the edge T1 of the first transition region 111b is in contact with the non-lithium-inserted area of the second active material layer 22, less heat is generated and the safety risk is lower.
  • the lithium ions in the first active material layer 12 diffuse freely to the surroundings. Therefore, in the longitudinal direction X, the size of the lithium intercalation region of the second active material layer 22 is slightly larger than the size of the first active material layer. .
  • the edge of the first transition region 111b exceeds the edge of the first active material layer 12 by at least 0.5 mm. In other words, in the longitudinal direction X, the size of the first transition region 111b is greater than or equal to 0.5 mm.
  • the first pole piece 1 further includes an insulating layer 13, and the insulating layer 13 is at least partially coated on the surface of the first transition region 111b.
  • the insulating layer 13 may be filled into the gap between the first transition region 111b and the second active material layer 22 of the second pole piece 2, thereby reducing impurities falling into the gap and further reducing the risk of short circuit.
  • coating the insulating layer 13 on the first transition region 111b can also prevent the first transition region 111b from electrically communicating with the second active material layer 22 of the second pole piece 2 through metal impurities.
  • the insulating layer 13 includes a first portion 131 and a second portion 132.
  • the first portion 131 is coated on the surface of the first transition region 111 b, and the second portion 132 extends from the first portion 131 and is coated on the surface of the first tab 112.
  • the first portion 131 completely covers the surface of the first transition region 111b.
  • the first part 131 can be filled into the gap between the first transition region 111b and the second active material layer 22 of the second pole piece 2, thereby reducing impurities falling into the gap and further reducing the risk of short circuit. Furthermore, coating the first portion 131 on the surface of the first transition region 111b can also prevent the first transition region 111b from electrically communicating with the second active material layer 22 of the second pole piece 2 through metal impurities.
  • the first active material layer 12 and the insulating layer 13 are coated on the surface of the first current collector 11 first, and then the first pole ear 112 is cut out.
  • the insulating layer 13 is generally coated with a uniform width. If the second part 132 is not reserved on the first tab 112, the cutter needs to move along the edge of the insulating layer 13 when cutting the first tab 112.
  • the precision requirement of ⁇ is relatively high, and it is difficult to achieve; in addition, after the cutting is completed, the burr on the edge T1 of the first transition zone 111b is relatively large, and the diaphragm 3 is easily pierced.
  • the cutter is directly applied to the insulating layer 13.
  • the insulating layer 13 forms a first portion 131 remaining on the first transition region 111 b and a second portion 132 remaining on the first tab 112.
  • the cutter cuts on the insulating layer 13 the burrs on the edge T1 of the first transition area 111b can be effectively reduced, thereby reducing the risk of the diaphragm 3 being punctured.
  • the edge T3 of the second portion 132 away from the first portion 131 extends beyond the edge T2 of the second active material layer 22.
  • the second portion 132 may be filled into the gap between the first tab 112 and the second active material layer 22, thereby reducing impurities falling into the gap and reducing the risk of short circuit.
  • the second portion 132 can also reduce the risk of the burrs on the edge of the first tab 112 being electrically connected to the second active material layer 22 after piercing the diaphragm 3.
  • the first tabs 112 are multiple and arranged in a layered manner, and the plurality of first tabs 112 are gathered together and welded to the current collecting member 8. In the process of closing the first tab 112, the roots of some first tabs 112 close to the first transition zone 111b are easily bent, causing the roots of these first tabs 112 to be inserted into the first pole piece 1 and the second pole. Between slices 2, there is a risk of short circuit.
  • the second part 132 of the embodiment of the present application can support the first tab 112, reducing the risk of bending the root of the first tab 112.
  • edge T3 of the second part 132 exceeds the edge T2 of the second active material layer 22, even if the first tab 112 is bent in the area where the second part 132 is not coated, the bent position is different from the second active material layer. A certain distance is maintained between the material layers 22, and the risk of contact between the first tab 112 and the second active material layer 22 is low.
  • the edge T3 of the second portion 132 away from the first portion 131 exceeds the edge of the second active material layer 22 by 0.3 mm-14 mm. If the size of the edge T3 of the second part 132 beyond the edge T2 of the second active material layer 22 is less than 0.3 mm, when the first tab 112 is bent in the area where the second part 132 is not coated, the bending position is the same as The distance between the second active material layers 22 is relatively small, and there is still a risk of contact between the first tab 112 and the second active material layer 22.
  • edge T3 of the second portion 132 exceeds the edge T2 of the second active material layer 22 by more than 14 mm, the degree of bendability of the first tab 112 is low, and the occupied space is large, which affects the energy density of the secondary battery.
  • the hardness of the insulating layer 13 is greater than the hardness of the first current collector 11.
  • the insulating layer 13 with high hardness can effectively support the first tab 112 and prevent the root of the first tab 112 from being bent close to the first transition region 111b.
  • the insulating layer 13 includes an inorganic filler and a binder, and the weight ratio of the inorganic filler to the binder is 4.1-9.6. If the ratio is greater than 9.6, the adhesion between the inorganic fillers and the bonding strength between the insulating layer 13 and the first current collector 11 may be insufficient, and the insulating layer 13 may easily fall off when in contact with the electrolyte. If the ratio is lower than 4.1, the insulating effect of the insulating layer 13 is difficult to meet the requirements; in addition, there are less inorganic fillers, which cannot play the role of supporting the first tab 112, resulting in the first tab 112 being easily placed in the first tab 112. The pole piece 1 is folded during the winding process.
  • the inorganic filler can be selected from one or more of boehmite, alumina (Al2O3), silica (SiO2) and titanium dioxide (TiO2).
  • the binder may be polyvinylidene fluoride.
  • the second active material layer 22 completely covers the second body portion 211.
  • the second pole piece 2 further includes a third active material layer 23, which is coated on the surface of the second tab 212 and connected to the second active material layer 22.
  • the second active material layer 22 and the third active material layer 23 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 21.
  • the negative electrode slurry is cured to form a negative electrode active material layer, and then the second tab 212 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 211 is the second active material layer 22, and the portion of the negative active material layer remaining on the second tab 212 is the third active material Layer 23.
  • Cutting on the negative active material layer can reduce burrs at the cut and reduce the risk of the separator 3 being punctured.
  • the active material of the negative electrode active material layer is relatively inexpensive, so a part of the negative electrode active material layer can be directly removed.
  • the first tab 112 and the second tab 212 are located on the same side of the electrode assembly along the longitudinal direction X.
  • the second active material layer 22 it is usually necessary to cold press the second active material layer 22 to increase the density of the second active material layer 22.
  • the end of the second active material layer 22 close to the second tab 212 is prone to stress concentration, which may cause the risk of the second current collector 21 breaking.
  • the second active material layer 22 includes a base region 221 and a thinned region 222 extending from the base region 221, and the thickness of the thinned region 222 is smaller than the thickness of the base region 221.
  • the thinning area 222 is connected to the side of the base area 221 close to the second tab 212.
  • the thickness of the thinned region 222 gradually decreases.
  • the stress concentration at the edge T4 of the thinned area 222 away from the base region 211 can be reduced, and the first The second collector 21 is broken.
  • the edge T1 of the first coating region 111a far away from the first transition region 111b extends beyond the junction of the base region 221 and the thinned region 222, and does not exceed the cut The edge T4 of the thin region 222 away from the base region 221. If the edge T1 of the first transition region 111b does not exceed the junction of the base region 221 and the skived region 222, the active material in the skived region 222 will be wasted.
  • the embodiments of this application can still meet the requirements.
  • the third active material layer 23 is connected to the thinned area 222.
  • the thickness of the third active material layer 23 is smaller than the thickness of the base region 221.
  • the size of the third active material layer 23 along the longitudinal direction X is larger, and the size of the thinning area 222 along the longitudinal direction X is smaller.
  • the smaller the size of the thinned area 222 is, the area where the second active material layer 22 overlaps the first transition area 111b can be reduced, and the risk of short circuit can be reduced.
  • the size of the third active material layer 23 along the direction of the skived area 222 pointing to the third active material layer 23 is larger than the size of the skived area 222.
  • the edge T1 of the first transition zone 111b shrinks into the second active material layer 22. Therefore, even if the root of the second tab 212 is bent, it is with the edge T1 of the first transition zone 111b. The risk of exposure is also small. Therefore, the embodiments of the present application can effectively reduce the risk of short circuit and improve safety performance.
  • the third embodiment can omit the third active material layer 23 compared with the first embodiment.
  • the second body portion 211 includes a second coating area 211a and a second transition area 211b, and the second transition area 211b is disposed between the second tab 212 and the second coating area 211a.
  • the second active material layer 22 is coated on the surface of the second coating area 211a, and the second transition area 211b is not coated with the second active material layer 22.
  • the tool can be prevented from acting on the second active material layer 22 due to process errors.
  • the third embodiment can save the second active material layer 22.
  • the current collecting member 8 When the secondary battery vibrates, the current collecting member 8 will pull the second body part 211 through the second tab 212. If there is no second transition zone 211b, stress concentration will occur at the root of the second tab 212, and the portion of the second active material layer 22 close to the root of the second tab 212 will easily fall off. However, by providing the second transition zone 211b in the embodiment of the present application, the force transferred to the second active material layer 22 can be reduced, and the risk of the active material in the second active material layer 22 falling off can be reduced.
  • the secondary battery described above may be referred to as a battery cell.

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Abstract

一种电极组件（4）和电池单体，该电极组件（4）包括第一极片（1）和第二极片（2）。第一极片（1）包括第一集流体（11）和第一活性物质层（12），第一集流体（11）包括第一主体部（111）和第一极耳（112），第一极耳（112）从第一主体部（111）沿纵向的一端延伸。第一主体部（111）包括第一涂覆区（111a）和第一过渡区（111b），第一过渡区（111b）设置于第一极耳（112）和第一涂覆区（111a）之间；第一活性物质层（12）涂覆于第一涂覆区（111a）的表面，第一过渡区（111b）和第一极耳（112）均未涂覆第一活性物质层（12）。第二极片（2）包括第二集流体（21）和第二活性物质层（22），第二集流体（21）包括第二主体部（211）和第二极耳（212），第二极耳（212）从第二主体部（211）沿纵向的一端延伸，第二活性物质层（22）涂覆于第二主体部（211）的表面。第一过渡区（111b）的远离第一涂覆区（111a）的边缘不超出第二活性物质层（22）的边缘。

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201910750738.2、发明名称为“电极组件和二次电池”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
二次电池的电极组件包括极片和隔膜，而极片包括集流体和涂覆于集流体表面的活性物质层。为了便于与二次电池的电极端子电连接，通常会在集流体上裁切出极耳。在裁切极耳之前，集流体具有涂覆有活性物质层的涂覆区和未涂覆活性物质层的未涂覆区，而极耳则是通过裁切未涂覆区形成。在裁切极耳的过程中，刀具很容易作用在活性物质层上，引发活性物质层脱落的风险，造成物料的浪费。
发明内容
鉴于背景技术中存在的问题，本申请的多个方面提供一种电极组件和电池单体。
本申请的第一方面提供一种电极组件，包括第一极片和第二极片，第一极片包括第一集流体和第一活性物质层，第一集流体包括第一主体部和第一极耳，第一极耳从第一主体部沿纵向的一端延伸。第一主体部包括第一涂覆区和第一过渡区，第一过渡区设置于第一极耳和第一涂覆区之间；第一活性物质层涂覆于第一涂覆区的表面，第一过渡区和第一极耳均未涂覆第一活性物质层。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第二极耳，第二极耳从第二主体部沿纵向的一端延伸，第二活性物质层涂覆于第二主体部的表面。沿第一主体部指向第一极耳的方向，第一过渡区的远离第一涂覆区的边缘不超出第二活性物质层的边缘。
可选地，第一极片为正极极片，第二极片为负极极片，并且沿第一主体部指向第一极耳的方向，第二活性物质层的边缘超出第一活性物质层的边缘。
可选地，沿第一主体部指向第一极耳的方向，第一过渡区的边缘至少超出第一活性物质层的边缘0.5毫米(mm)。
可选地，第一极片还包括绝缘层，绝缘层至少部分涂覆于第一过渡区的表面。
可选地，绝缘层包括第一部分和第二部分，第一部分涂覆于第一过渡区的表面，第二部分从第一部分延伸且涂覆于第一极耳的表面。
可选地，沿第一主体部指向第一极耳的方向，第二部分的远离第一部分的边缘超出第二活性物质层的边缘。
可选地，沿第一主体部指向第一极耳的方向，第二部分的远离第一部分的边缘超出第二活性物质层的边缘0.3mm-14mm。
可选地，绝缘层的硬度大于第一集流体的硬度。
可选地，绝缘层包括无机填料和粘结剂，所述无机填料和粘结剂的重量的比值为0.4-6.5。
可选地，第一极耳和第二极耳位于电极组件沿纵向的同一侧。第二活性物质层包括基体区和从基体区延伸的削薄区，且削薄区的厚度小于基体区的厚度。在纵向上，削薄区连接于基体区的靠近第二极耳的一侧。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连接于削薄区。沿削薄区指向第三活性物质层的方向，第三活性物质层的尺寸大于削薄区的尺寸。
可选地，第二主体部包括第二涂覆区和第二过渡区，第二过渡区设置于第二极耳和第二涂覆区之间。第二活性物质层涂覆于第二涂覆区的表面，第二过渡区未涂覆第二活性物质层。
可选地，所述电极组件还包括隔膜，所述隔膜用于将所述第一极片和所述第二极片隔开。
本申请的第二方面提供一种电池单体，包括所述的电极组件。
上述描述的电极组件和电池单体，在电极组件中通过集流体上设置第一过渡区，可以避免第一活性物质层在裁切第一极耳的过程中脱落。同时，第一过渡区还能够在电池单体震动时减小传递到第一活性物质层的作用力，降低第一活性物质层脱落的风险。另外，还能够减小第一过渡区和第二活性物 质层的重叠面积，减小杂质掉入两者之间的概率，降低两者接触和短路的风险。
附图说明
图1为根据本申请一实施例的二次电池的示意图。
图2为根据本申请的电极组件的第一实施例的示意图。
图3为图2的电极组件沿线A-A作出的剖视图。
图4为图2的电极组件沿线B-B作出的剖视图。
图5为图4的电极组件在方框C处的放大图。
图6为图4的电极组件在方框D处的放大图。
图7为图4的第一极片在展开状态下的示意图。
图8为图7的第一极片的第一集流体的示意图。
图9为图7的第一极片在成型过程中的示意图。
图10为图4的第二极片在展开状态下的示意图。
图11为图10的第二极片的第二集流体的示意图。
图12为根据本申请的电极组件的第二实施例的示意图。
图13为图12的电极组件沿线E-E作出的剖视图。
图14为图13的电极组件在方框F处的放大图。
图15为图13的第二极片在展开状态下的示意图。
图16为根据本申请的电极组件的第三实施例的示意图。
图17为图16的电极组件在方框G处的放大图。
图18为图16的第二极片在展开状态下的示意图。
其中，附图标记说明如下：
1第一极片
11第一集流体
111第一主体部
111a第一涂覆区
111b第一过渡区
112第一极耳
12第一活性物质层
13绝缘层
131第一部分
132第二部分
2第二极片
21第二集流体
211第二主体部
211a第二涂覆区
211b第二过渡区
212第二极耳
22第二活性物质层
221基体区
222削薄区
23第三活性物质层
3隔膜
4电极组件
5壳体
6顶盖板
7电极端子
8集流构件
X纵向
Y横向
Z厚度方向
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，本申请一实施例的二次电池包括电极组件4、壳体5、顶盖板6、电极端子7和集流构件8。
电极组件4是二次电池实现充放电功能的核心构件。参照图2和图3，电极组件4包括第一极片1、第二极片2和隔膜3，隔膜3将第一极片1和第二极片2隔开。
电极组件4可为卷绕式结构。具体地，第一极片1和第二极片2均为一个，且第一极片1和第二极片2为带状结构。将第一极片1、隔膜3和第二极片2依次层叠并卷绕两圈以上以形成电极组件4。电极组件4可为扁平状。
可替代地，电极组件4也可为叠片式结构。具体地，第一极片1设置为多个，第二极片2设置为多个，所述多个第一极片1和第二极片2交替层叠，隔膜3将第一极片1和第二极片2隔开。
壳体5可具有六面体形状或其它形状。壳体5内部形成收容腔，以容纳电极组件4和电解液。壳体5在一端形成开口，而电极组件4可经由所述开口放置到壳体5的收容腔。壳体5可由导电金属的材料制成，可选地，壳体5由铝或铝合金制成。
顶盖板6设置于壳体5并覆盖壳体5的开口，从而将电极组件4密封在壳体5内。顶盖板6可为金属板，且通过焊接的方式连接于壳体5。电极端子7为两个且设置于顶盖板6。集流构件8为两个，一个集流构件8连接一个电极端子7和电极组件4的第一极片1，另一个集流构件8连接另一个电极端子7和电极组件4的第二极片2。
下面以不同的实施例向下描述本申请的电极组件。
在第一实施例中，参照图4至图6，第一极片1包括第一集流体11和第一活性物质层12，第一集流体11包括第一主体部111和第一极耳112，第一极耳112从第一主体部111沿纵向X的一端延伸。第一活性物质层12涂覆于第一主体部111的表面。第一极片1可为正极极片，对应地，第一集流体11为铝箔，第一活性物质层12包括三元材料、锰酸锂或磷酸铁锂。第一极耳112 可为多个。当第一极片1卷绕成型后，多个第一极耳112层叠在一起并焊接于集流构件8。
第二极片2包括第二集流体21和第二活性物质层22，第二集流体21包括第二主体部211和第二极耳212，第二极耳212从第二主体部211沿纵向X的一端延伸，第二活性物质层22涂覆于第二主体部211的表面。第二极片2可为负极极片，对应地，第二集流体21为铜箔，第二活性物质层22包括石墨或硅。第二极耳212可为多个。当第二极片2卷绕成型后，多个第二极耳212层叠在一起并焊接于集流构件8。
在本实施例中，参照图2，第一极耳112和第二极耳212分别位于电极组件4沿纵向X的两侧。
在电池的使用过程中，第一活性物质层12中的锂离子穿过隔膜3并嵌入到第二活性物质层22中。为保证锂离子能够尽可能地嵌入第二活性物质层22，降低析锂风险，第二活性物质层22需要具有较大的宽度。具体地，第二活性物质层22沿纵向X的两端均超出第一活性物质层12。换句话说，沿第一主体部111指向第一极耳112的方向，第二活性物质层22的靠近第一极耳112的一个边缘T2超出第一活性物质层12的靠近第一极耳112的一个边缘；沿第一极耳112指向第一主体部111的方向，第二活性物质层22的远离第一极耳112的另一个边缘超出第一活性物质层12的远离第一极耳112的另一个边缘。
在第一极片1的成型过程中，需要通过裁切在第一集流体11上形成第一极耳112。如果沿着第一活性物质层12的边缘进行裁切，那么刀具很容易因为工艺误差作用在第一活性物质层12上，导致第一活性物质层12中的活性材料脱落，造成物料的浪费。相对而言，第一活性物质层12中的活性材料较为昂贵，因此，沿着第一活性物质层12的边缘裁切会导致第一极片1的成本偏高。
为了避免刀具作用在第一活性物质层12上，本申请实施例增加第一主体部111沿纵向X的尺寸，以增大第一活性物质层12和第一极耳112在纵向X上的间距。具体地，参照5至图9，第一主体部111包括第一涂覆区111a和第一过渡区111b，第一过渡区111b设置于第一极耳112和第一涂覆区111a之间；第一活性物质层12涂覆于第一涂覆区111a的表面，第一过渡区111b和第一极耳112均未涂覆第一活性物质层12。
图9的虚线示出了刀具在裁切第一极耳112的过程中的运动轨迹。在裁切第一极耳112的过程中，刀具与第一活性物质层12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12上，防止第一活性物质层12的活性材料脱落。参照图7和图8，裁切完成后，第一主体部111上形成未涂覆第一活性物质层12的第一过渡区111b。
在二次电池震动时，集流构件8会通过第一极耳112拉扯第一主体部111。如果没有第一过渡区111b，那么第一极耳112的根部会产生应力集中，第一活性物质层12靠近第一极耳112的根部的部分容易脱落。而本申请实施例通过设置第一过渡区111b，可以减小传递到第一活性物质层12的作用力，降低第一活性物质层12中的活性材料脱落的风险。
当电极组件4卷绕成型后，第一极片1和第二极片2层叠在一起。第一涂覆区111a的表面涂覆有第一活性物质层12，因此，第一涂覆区111a与第二极片2的第二活性物质层22之间的间隙较小；而第一过渡区111b未涂覆第一活性物质层12，因此，第一过渡区111b与第二极片2的第二活性物质层22之间的间隙较大。
在第一极耳112与集流构件8的焊接过程中会产生杂质(例如金属颗粒等)，而由于第一过渡区111b与第二活性物质层22之间的间隙较大，所以杂质很容易掉落在该间隙中。在充放电的过程中，第一极片1和第二极片2会出现膨胀，膨胀时可能挤压掉落在间隙中的杂质，从而使杂质刺破隔膜3，引发短路风险。
可选地，参照图5，沿第一主体部111指向第一极耳112的方向，第一过渡区111b的远离的第一涂覆区111a的边缘T1不超出第二活性物质层22的边缘T2。这样可以减小第一过渡区111b和第二活性物质层22的重叠面积，从而降低两者接触和短路的风险。同时，本申请实施例还减小了第一过渡区111b与第二活性物质层22之间的间隙沿纵向X的尺寸，从而降低了杂质掉入所述间隙的风险。另外，在纵向X上，第一过渡区111b的边缘T1收缩到第二活性物质层22内，从而降低了边缘T1吸附杂质的风险。
在裁切第一极耳112的过程中，第一过渡区111b的远离第一涂覆区111a的边缘T1上会产生毛刺，而毛刺则容易刺破隔膜3。
在电池的使用过程中，第一活性物质层12中的锂离子穿过隔膜3并嵌入到第二活性物质层22中。如果第一过渡区111b的边缘T1上的毛刺与第二活 性物质层22的嵌锂区域接触，那么会瞬间产生大量的热量，引发爆炸风险。而如果第一过渡区111b的边缘T1上的毛刺与第二活性物质层22的未嵌锂区域接触，则产热较少，安全风险较低。
在电池的使用过程中，第一活性物质层12中的锂离子向周围自由扩散，因此，在纵向X上，第二活性物质层22的嵌锂区域的尺寸略大于第一活性物质层的尺寸。为了降低安全风险，沿第一主体部111指向第一极耳112的方向，第一过渡区111b的边缘至少超出第一活性物质层12的边缘0.5mm。换句话说，在纵向X上，第一过渡区111b的尺寸大于等于0.5mm。此时，即使第一过渡区111b的边缘T1上的毛刺刺破隔膜3，也只会与第二活性物质层22的未嵌锂区域接触，进而避免爆炸，降低安全风险。
参照图5和图7，第一极片1还包括绝缘层13，绝缘层13至少部分涂覆于第一过渡区111b的表面。绝缘层13可以填充到第一过渡区111b与第二极片2的第二活性物质层22之间的间隙内，从而减少掉落到所述间隙内的杂质，进一步降低短路风险。再者，在第一过渡区111b涂覆绝缘层13，还可以防止第一过渡区111b与第二极片2的第二活性物质层22通过金属杂质电连通。
绝缘层13包括第一部分131和第二部分132，第一部分131涂覆于第一过渡区111b的表面，第二部分132从第一部分131延伸且涂覆于第一极耳112的表面。可选地，第一部分131完全覆盖第一过渡区111b的表面。
第一部分131可以填充到第一过渡区111b与第二极片2的第二活性物质层22之间的间隙内，从而减少掉落到所述间隙内的杂质，进一步降低短路风险。再者，在第一过渡区111b的表面涂覆第一部分131，还可以防止第一过渡区111b与第二极片2的第二活性物质层22通过金属杂质电连通。
参照图9，在第一极片1的成型过程中，先在第一集流体11的表面涂覆第一活性物质层12和绝缘层13，然后再裁切出第一极耳112。绝缘层13一般为等宽度涂覆，如果不在第一极耳112上保留第二部分132，那么在裁切第一极耳112时，刀具需要沿着绝缘层13的边缘运动，这对裁切的精度要求较高，难以实现；另外，裁切完成后，第一过渡区111b的边缘T1上的毛刺较大，容易刺破隔膜3。
因此，本申请实施例在裁切第一极耳112的过程中，直接将刀具作用在绝缘层13上。裁切完成后，绝缘层13形成保留在第一过渡区111b上的第一部分131和保留在第一极耳112上的第二部分132。另外，当刀具在绝缘层 13上裁切时，可以有效地减小第一过渡区111b的边缘T1上的毛刺，从而降低隔膜3被刺破的风险。
参照图5，沿第一主体部111指向第一极耳112的方向，第二部分132的远离第一部分131的边缘T3超出第二活性物质层22的边缘T2。第二部分132可以填充到第一极耳112和第二活性物质层22之间的间隙内，从而减少掉入所述间隙的杂质，降低短路风险。再者，第二部分132还可以降低第一极耳112的边缘的毛刺在刺破隔膜3后与第二活性物质层22电连通的风险。
第一极耳112为多个且层叠布置，所述多个第一极耳112收拢在一起并焊接于集流构件8。在收拢第一极耳112的过程中，一些第一极耳112的靠近第一过渡区111b的根部容易折弯，导致这些第一极耳112的根部插入到第一极片1和第二极片2之间，引发短路风险。而本申请实施例的第二部分132可以支撑第一极耳112，降低第一极耳112的根部折弯的风险。另外，由于第二部分132的边缘T3超出第二活性物质层22的边缘T2，因此，即使第一极耳112在未涂覆第二部分132的区域弯折，弯折的位置与第二活性物质层22之间保持一定的距离，第一极耳112与第二活性物质层22接触的风险较低。
沿第一主体部111指向第一极耳112的方向，第二部分132的远离第一部分131的边缘T3超出第二活性物质层22的边缘0.3mm-14mm。如果第二部分132的边缘T3超出第二活性物质层22的边缘T2的尺寸小于0.3mm，那么当第一极耳112在未涂覆第二部分132的区域弯折时，弯折的位置与第二活性物质层22之间的距离较小，仍存在第一极耳112与第二活性物质层22接触的风险。如果第二部分132的边缘T3超出第二活性物质层22的边缘T2的尺寸大于14mm，那么第一极耳112的可弯折的程度低，占用的空间大，影响二次电池的能量密度。
绝缘层13的硬度大于第一集流体11的硬度。高硬度的绝缘层13可以有效地支撑第一极耳112，避免第一极耳112的靠近第一过渡区111b的根部折弯。
绝缘层13包括无机填料和粘结剂，所述无机填料和粘结剂的重量的比值为4.1-9.6。如果所述比值大于9.6，那么无机填料之间的粘着性以及绝缘层13与第一集流体11之间的粘接强度可能会不足，当与电解液接触时，绝缘层13容易脱落。如果所述比值低于4.1时，那么绝缘层13的绝缘效果难以满足要求；再者，无机填料较少，无法起到支撑第一极耳112的作用，导致第一极 耳112容易在第一极片1的卷绕过程中翻折。无机填料可选自勃姆石、氧化铝(Al2O3)、二氧化硅(SiO2)和二氧化钛(TiO2)中的一种或几种。粘结剂可为聚偏二氟乙烯。
在本实施例中，参照图10和图11，第二活性物质层22完全覆盖第二主体部211。第二极片2还包括第三活性物质层23，第三活性物质层23涂覆于第二极耳212的表面且连接于第二活性物质层22。第二活性物质层22和第三活性物质层23一体成型。
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21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212。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211上的部分即为第二活性物质层22，负极活性物质层的保留在第二极耳212上的部分即为第三活性物质层23。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3被刺破的风险。另外，相对而言，负极活性物质层的活性材料较为廉价，所以可以直接切除部分的负极活性物质层。
下面对本申请的电极组件的其它实施例进行说明。为了简化描述，以下仅主要介绍其它实施例与第一实施例的不同之处，未描述的部分可以参照第一实施例进行理解。
参照图12至图15，在第二实施例中，第一极耳112和第二极耳212位于电极组件沿纵向X的同一侧。
在第二极片2的成型过程中，通常需要对第二活性物质层22进行冷压，以提高第二活性物质层22的密度。在冷压时，第二活性物质层22的靠近第二极耳212的端部容易产生应力集中，引发第二集流体21断裂的风险。
可选地，第二活性物质层22包括基体区221和从基体区221延伸的削薄区222，且削薄区222的厚度小于基体区221的厚度。在纵向X上，削薄区222连接于基体区221的靠近第二极耳212的一侧。可选地，沿远离基体区221的方向，削薄区222的厚度逐渐减小。
在本申请实施例中，通过减小削薄区222的厚度，在第二极片2的冷压过程中，可以降低削薄区222的远离基体区211的边缘T4处的应力集中，避 免第二集流体21断裂。
参照图14，沿基体区221指向削薄区222的方向，第一过渡区111b的远离的第一涂覆区111a的边缘T1超出基体区221和削薄区222的连接处，且不超出削薄区222的远离基体区221的边缘T4。如果第一过渡区111b的边缘T1不超出基体区221和削薄区222的连接处，那么将会导致削薄区222的活性材料浪费。虽然减小削薄区222的厚度会增大第一过渡区111b和削薄区222之间的间隙，但是涂覆于第一过渡区111b的第一部分131可以弥补间隙增大带来的安全风险，所以本申请实施例仍然能够满足要求。
在第二实施例中，第三活性物质层23连接于削薄区222。第三活性物质层23的厚度小于基体区221的厚度。在裁切第二极耳212时，第三活性物质层23沿纵向X的尺寸越大，削薄区222沿纵向X的尺寸越小。本申请实施例通过减小削薄区222的尺寸越小，可以减小第二活性物质层22与第一过渡区111b重叠的面积，降低短路风险。通过增大第三活性物质层23的尺寸，可以减小第二极耳212根部弯折的概率，降低短路风险。综合考虑，沿削薄区222指向第三活性物质层23的方向，第三活性物质层23的尺寸大于削薄区222的尺寸。
参照图14，在纵向X上，第一过渡区111b的边缘T1收缩到第二活性物质层22内，因此，即使第二极耳212的根部折弯，其与第一过渡区111b的边缘T1接触的风险也较小。因此，本申请实施例可以有效地降低短路风险，提高安全性能。
参照图16至图18，与第一实施例相比，第三实施例可以省略第三活性物质层23。具体地，第二主体部211包括第二涂覆区211a和第二过渡区211b，第二过渡区211b设置于第二极耳212和第二涂覆区211a之间。第二活性物质层22涂覆于第二涂覆区211a的表面，第二过渡区211b未涂覆第二活性物质层22。
通过设置第二过渡区211b，可以避免刀具因工艺误差作用在第二活性物质层22上。与第一实施例相比，第三实施例可以节省第二活性物质层22。
在二次电池震动时，集流构件8会通过第二极耳212拉扯第二主体部211。如果没有第二过渡区211b，那么第二极耳212的根部会产生应力集中，第二活性物质层22靠近第二极耳212的根部的部分容易脱落。而本申请实施例通过设置第二过渡区211b，可以减小传递到第二活性物质层22的作用力，降低 第二活性物质层22中的活性材料脱落的风险。
本申请的另一实施例中，上述描述的二次电池可以称为电池单体。

Claims (13)

  1. 一种电极组件，其特征在于，包括第一极片(1)和第二极片(2)；
    所述第一极片(1)包括第一集流体(11)和第一活性物质层(12)，所述第一集流体(11)包括第一主体部(111)和第一极耳(112)，所述第一极耳(112)从所述第一主体部(111)沿纵向(X)的一端延伸；
    所述第一主体部(111)包括第一涂覆区(111a)和第一过渡区(111b)，所述第一过渡区(111b)设置于所述第一极耳(112)和所述第一涂覆区(111a)之间；所述第一活性物质层(12)涂覆于所述第一涂覆区(111a)的表面，所述第一过渡区(111b)和所述第一极耳(112)均未涂覆所述第一活性物质层(12)；
    所述第二极片(2)包括第二集流体(21)和第二活性物质层(22)，所述第二集流体(21)包括第二主体部(211)和第二极耳(212)，所述第二极耳(212)从所述第二主体部(211)沿纵向(X)的一端延伸，所述第二活性物质层(22)涂覆于所述第二主体部(211)的表面；
    沿所述第一主体部(111)指向所述第一极耳(112)的方向，所述第一过渡区(111b)的远离所述第一涂覆区(111a)的边缘不超出所述第二活性物质层(22)的边缘。
  2. 根据权利要求1所述的电极组件，其特征在于，所述第一极片(1)为正极极片，所述第二极片(2)为负极极片，并且沿所述第一主体部(111)指向所述第一极耳(112)的方向，所述第二活性物质层(22)的边缘超出所述第一活性物质层(12)的边缘。
  3. 根据权利要求2所述的电极组件，其特征在于，沿所述第一主体部(111)指向所述第一极耳(112)的方向，所述第一过渡区(111b)的边缘至少超出所述第一活性物质层(12)的边缘0.5毫米。
  4. 根据权利要求1-3中任一项所述的电极组件，其特征在于，所述第一极片(1)还包括绝缘层(13)，所述绝缘层(13)至少部分涂覆于所述第一过渡区(111b)的表面。
  5. 根据权利要求4所述的电极组件，其特征在于，所述绝缘层(13)包括第一部分(131)和第二部分(132)，所述第一部分(131)涂覆于所述第一过渡区(111b)的表面，所述第二部分(132)从所述第一部分(131)延伸且涂覆于所述第一极耳(112)的表面。
  6. 根据权利要求5所述的电极组件，其特征在于，沿所述第一主体部(111)指向所述第一极耳(112)的方向，所述第二部分(132)的远离所述第一部分(131)的边缘超出所述第二活性物质层(22)的边缘。
  7. 根据权利要求6所述的电极组件，其特征在于，沿所述第一主体部(111)指向所述第一极耳(112)的方向，所述第二部分(132)的远离所述第一部分(131)的边缘超出所述第二活性物质层(22)的边缘0.3毫米-14毫米。
  8. 根据权利要求4-7任意一项所述的电极组件，其特征在于，所述绝缘层(13)的硬度大于所述第一集流体(11)的硬度。
  9. 根据权利要求4-8任意一项所述的电极组件，其特征在于，所述绝缘层(13)包括无机填料和粘结剂，所述无机填料和所述粘结剂的重量的比值为4.1-9.6。
  10. 根据权利要求1-9任意一项所述的电极组件，其特征在于，
    所述第一极耳(112)和所述第二极耳(212)位于所述电极组件沿纵向(X)的同一侧；
    所述第二活性物质层(22)包括基体区(221)和从所述基体区(221)延伸的削薄区(222)，且所述削薄区(222)的厚度小于所述基体区(221)的厚度；
    在纵向(X)上，所述削薄区(222)连接于所述基体区(221)的靠近所述第二极耳(212)的一侧；
    所述第二极片(2)还包括第三活性物质层(23)，所述第三活性物质层(23)涂覆于所述第二极耳(212)的表面且连接于所述削薄区(222)；
    沿所述削薄区(222)指向所述第三活性物质层(23)的方向，所述第三 活性物质层(23)的尺寸大于所述削薄区(222)的尺寸。
  11. 根据权利要求1-10任意一项所述的电极组件，其特征在于，
    所述第二主体部(211)包括第二涂覆区(211a)和第二过渡区(211b)，所述第二过渡区(211b)设置于所述第二极耳(212)和所述第二涂覆区(211a)之间；
    所述第二活性物质层(22)涂覆于所述第二涂覆区(211a)的表面，所述第二过渡区(211b)未涂覆所述第二活性物质层(22)。
  12. 根据权利要求1-11任意一项所述的电极组件，其特征在于，所述电极组件还包括隔膜(3)，所述隔膜(3)用于将所述第一极片(1)和所述第二极片(2)隔开。
  13. 一种电池单体，其特征在于，包括权利要求1-12中任一项所述的电极组件。
PCT/CN2020/102829 2019-08-14 2020-07-17 电极组件和电池单体 WO2021027490A1 (zh)

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CN113224261A (zh) * 2021-04-30 2021-08-06 珠海冠宇电池股份有限公司 极片和电池

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