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WO2018024203A1 - Pole piece and electrochemical cell - Google Patents

Pole piece and electrochemical cell Download PDF

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Publication number
WO2018024203A1
WO2018024203A1 PCT/CN2017/095511 CN2017095511W WO2018024203A1 WO 2018024203 A1 WO2018024203 A1 WO 2018024203A1 CN 2017095511 W CN2017095511 W CN 2017095511W WO 2018024203 A1 WO2018024203 A1 WO 2018024203A1
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WO
WIPO (PCT)
Prior art keywords
pole piece
protrusions
current collector
negative electrode
electrode tab
Prior art date
Application number
PCT/CN2017/095511
Other languages
French (fr)
Chinese (zh)
Inventor
许虎
史东洋
金海族
任苗苗
林玉春
Original Assignee
宁德时代新能源科技股份有限公司
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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
Publication of WO2018024203A1 publication Critical patent/WO2018024203A1/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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • 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
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to the field of batteries, and in particular to a pole piece and a battery core.
  • lithium ion batteries have been widely used as power batteries. With the increasingly fierce market competition, major lithium-ion battery companies have continuously explored and improved the performance and manufacturing process of power lithium-ion batteries.
  • the battery core As the core component of lithium-ion battery, the battery core is usually laminated and wound. The winding method is adopted by the majority of lithium-ion battery manufacturers due to the simple process, high assembly efficiency and easy automation.
  • the pole piece after winding is more likely to occur, and the tensile deformation of the pole piece may cause short safety hazards in the lithium ion battery.
  • the continuously extruded pole piece causes the interlayer gap between the poles to be locked in the late cycle, resulting in poor electrolyte wettability, and insufficient electrolyte infiltration leads to deterioration of the cycle performance in the later stage.
  • the present invention provides a pole piece comprising: a current collector; and an active material layer coated on a surface of the current collector.
  • the pole piece has a plurality of protrusions, all of which are formed by the current collector and the active material layer on the surface of the current collector along the thickness direction of the pole piece The sides are convex outward, and all the protrusions are formed on the same side in the thickness direction of the pole piece.
  • the present invention provides a battery cell comprising: a positive electrode tab, a negative pole tab, and a separator.
  • the positive electrode tab includes: a cathode current collector; and a cathode active material layer coated on a surface of the cathode current collector.
  • the negative electrode tab includes: a negative electrode current collector; and a negative electrode active material layer coated on a surface of the negative electrode current collector.
  • the separator is located between the positive electrode tab and the negative electrode tab. Wherein at least one of the positive electrode tab and the negative electrode tab employs the pole piece according to the first aspect of the invention.
  • the pole piece since the pole piece has a plurality of protrusions which are outwardly convex from one side of the thickness direction of the pole piece by the current collector layer on the surface of the current collector and the current collector, the pole piece When applied to a battery cell, a plurality of protrusions can create a buffer space for the continuously expanding pole piece to release the expansion stress of the pole piece, thereby improving the safety performance and cycle performance of the battery core.
  • Figure 1 is a plan view of an electrode piece in accordance with an embodiment of the present invention.
  • Figure 2 is a front elevational view of Figure 1;
  • Figure 3 is an enlarged view of a circled portion of Figure 2;
  • Figure 4 is a plan view of a pole piece in accordance with another embodiment of the present invention.
  • Figure 5 is a front elevational view of Figure 4.
  • Figure 6 is an enlarged view of a circled portion in Figure 5;
  • Figure 7 is a plan view of a pole piece in accordance with another embodiment of the present invention.
  • Figure 8 is a front elevational view of Figure 7;
  • Figure 9 is an enlarged view of the block portion of Figure 8.
  • Figure 10 is a plan view of a pole piece in accordance with another embodiment of the present invention.
  • Figure 11 is a front elevational view of Figure 10;
  • Figure 12 is an enlarged view of the block portion of Figure 11;
  • Figure 13 is a deformation view of Figure 1;
  • Figure 14 is a front elevational view of Figure 13;
  • Figure 15 is an enlarged view of a circled portion in Figure 14;
  • Figure 16 is a cross-sectional view of an electric cell in accordance with an embodiment of the present invention.
  • Figure 17 is a cross-sectional view of a battery cell in accordance with another embodiment of the present invention.
  • H thickness direction 22 anode active material layer
  • a pole piece P includes: a current collector P1; and an active material layer P2 coated on a surface of the current collector P1.
  • the pole piece P has a plurality of protrusions S1, and all of the protrusions S1 are formed by the current collector P1 and the active material layer P2 on the surface of the current collector P1 projecting outward along one side of the thickness direction H of the pole piece P (this The inside of the projection S1 is a pit, and all the projections S1 are formed on the same side in the thickness direction H of the pole piece P.
  • the pole piece P since the pole piece P has a large amount of the current collector P1 and the active material layer P2 on the surface of the current collector P1, which protrudes outward along one side in the thickness direction H of the pole piece P, the protrusion S1, when the pole piece P is applied to the battery core, the plurality of protrusions S1 can create a buffer space for the continuously expanding pole piece P to release the expansion stress of the pole piece P, thereby improving the safety performance and circulation of the battery element. performance.
  • the pole piece P of the present invention in an embodiment, referring to Figs. 1, 4 and 13, all the projections S1 are distributed over the entire pole piece P, and the projection areas of all the projections S1 on the surface of the pole piece P are The sum accounts for 10% to 60% of the total area of the surface of the pole piece P, because all the protrusions S1 are on the surface of the pole piece P If the ratio of the sum of the projected areas on the surface of the pole piece P to the total area of the surface of the pole piece P is too small to alleviate the expansion stress of the pole piece P, if it is too large, a large pole piece P interface concentration difference will be brought. Risk of polarization.
  • all the protrusions S1 can be uniformly distributed uniformly over the entire pole piece P (this is the arrangement of the preferred protrusions S1), or can be randomly and randomly distributed throughout the pole piece P.
  • the pole piece P of the present invention in an embodiment, referring to Figs.
  • all the projections S1 form a plurality of spaced apart convex concentrated regions T, and all the projections S1 on each of the convex concentrated regions T
  • the sum of the projected areas on the surface of the raised concentration area T is 10%-60% of the total area of the surface of the raised concentrated area T, because all the protrusions S1 on each of the raised concentrated areas T are If the ratio of the sum of the projected areas on the surface of the raised concentrated area T to the total area of the surface of the raised concentrated area T is too small to alleviate the expansion stress of the pole piece P, if it is too large, Brings a large pole P interface concentration polarization risk. .
  • the projections S1 are distributed in an array along the longitudinal direction L and the width direction W of the pole piece P.
  • all the protrusions S1 are distributed in the entire pole piece P along the longitudinal direction L and the width direction W of the pole piece P; referring to FIG. 7, all the protrusions S1 in each of the protrusion concentration areas T are along the pole piece
  • An array of the longitudinal direction L and the width direction W of P is distributed in the convex concentration region T. It is added here that the manner in which such an array is distributed is applied to the projection S1 which is relatively small in volume and which can be roughly regarded as a dot-like structure.
  • the protrusions S1 are distributed in an array, there is a directional transmission path between the protrusions S1 and the protrusions S1, thereby facilitating the electrolyte transfer.
  • each of the projections S1 on the pole piece P may be circular, elliptical, or polygonal. Further, the polygon may be rectangular, triangular or trapezoidal. Correspondingly, the actual three-dimensional structure of each protrusion S1 may be a part of a sphere, a part of an ellipsoid, a rectangular parallelepiped, a prism, a prism or a truncated cone.
  • the diameter of the circular shape may be 2 mm to 10 mm.
  • the length of the rectangle may be 2 mm to 10 mm, and the width of the rectangle may be 2 mm to 10 mm.
  • each of the protrusions S1 extends along the width direction W of the pole piece P across the entire width of the pole piece P, that is, the width of each of the protrusions S1 is equal to the width of the pole piece P,
  • the span S1 may span from 1 mm to 10 mm in the longitudinal direction L of the pole piece P.
  • each of the protrusions S1 has a span of 3 mm to 6 mm along the longitudinal direction L of the pole piece P.
  • all the protrusions S1 are distributed over the entire pole piece P along the length direction L of the pole piece P; referring to FIG. 10, each convex set All the projections S1 in the middle portion T are distributed in the projection concentration region T along the length direction L of the pole piece P.
  • each of the protrusions S1 extends obliquely with respect to the width direction W of the pole piece P and obliquely across the entire width of the pole piece P, and at this time, each of the protrusions S1 is perpendicular to the extending direction of the protrusion S1.
  • the span in the direction may be 1 mm to 10 mm, and preferably, each of the protrusions S1 has a span of 3 mm to 6 mm in a direction perpendicular to the extending direction of the protrusion S1.
  • the size of the single protrusion S1 of different shapes described above needs to be properly set. Because the size of the protrusion S1 is too small, the interlayer gap of the pole piece P is small, and the relief piece P cannot be achieved. The effect of the expansion stress, if it is too large, causes damage to the pole piece P itself when pressed. Further, the size range of the projection S1 given above is only a preferred size in actual production, and it is of course not limited thereto, and may be appropriately changed depending on the specific circumstances.
  • the angle ⁇ between the extending direction of each of the protrusions S1 and the width direction W of the pole piece P is not more than 30 degrees.
  • the cross-sectional shape of the projection S1 on a plane perpendicular to the surface of the pole piece P is curved (as shown in Figs. 3, 9 and 15) or a multi-line segment.
  • the line shape (as shown in Figures 6 and 12).
  • the ratio of the height of each of the projections S1 to the thickness of the pole piece P may be 0.05 to 1.5. Further, the ratio of the height of each of the protrusions S1 to the thickness of the pole piece P may be 0.05 to 0.8, and further, the ratio of the height of each of the protrusions S1 to the thickness of the pole piece P may be 0.3 to 0.7. It is added here that the ratio between the height of each of the protrusions S1 and the thickness of the pole piece P illustrated in the relevant drawings does not represent the height of each of the protrusions S1 and the thickness of the pole piece P in the actual product. The ratio between the dimensions is merely to clearly illustrate the structure of each of the projections S1.
  • the pole piece P may have a thickness of 90 um to 130 um.
  • the pole piece P may have a thickness of 115 um.
  • each of the projections S1 on the pole piece P can be pressed by a press roll.
  • the battery cell according to the present invention includes a positive electrode tab 1, a negative electrode tab 2, and a separator 3.
  • the positive electrode tab 1 includes: a cathode current collector 11; and a cathode active material layer 12 coated on the positive electrode On the surface of the pole current collector 11.
  • the negative electrode tab 2 includes: a negative electrode current collector 21; and a negative electrode active material layer 22 coated on the surface of the negative electrode current collector 21.
  • the separator 3 is located between the positive electrode tab 1 and the negative electrode tab 2. Among them, at least one of the positive electrode tab 1 and the negative electrode tab 2 employs the pole piece P according to the first aspect of the invention.
  • the plurality of projections S1 in the pole piece P can be continuously expanded
  • the cells create a buffer space to release the expansion stress of the cell, thereby improving the safety and cycle performance of the cell.
  • only the positive electrode tab 1 employs the pole piece P of the first aspect of the invention.
  • the negative electrode tab 2 employs the pole piece P of the first aspect of the invention. This is because when the compact density of the positive electrode tab 1 is high, the positive electrode tab 1 is relatively brittle and is easily broken during the pressing process. In this case, the projection S1 can be selectively disposed on the negative pole piece having low compacting density and good toughness. 2 on.
  • the positive electrode tab 1 and the negative electrode tab 2 each employ the pole piece P of the first aspect of the invention. It is additionally noted that since the positive electrode tab 1 and the negative electrode tab 2 are each provided with a projection S1, the projection S1 on the positive pole tab 1 and the negative pole tab 2 can together create a buffer for the continuously expanding cell. The space is to release the expansion stress of the cell, so that the heights of the protrusions S1 on the positive electrode tab 1 and the negative electrode tab 2 need not be set too high, thereby reducing the protrusion S1 during the press forming process to the positive pole tab 1 and Damage to the negative electrode tab 2.
  • the cells may be laminated cells.
  • the battery cells are wound cells.
  • the positive electrode tab 1 is formed with a positive electrode flat portion A1 and a positive electrode bent portion A2 (ie, a winding turn) at the time of winding
  • the negative electrode tab 2 is formed with a negative electrode flat portion B1 and a negative electrode bent portion B2 at the time of winding. (ie winding the turn).
  • the protrusion S1 on the positive electrode pole piece 1 may be distributed on the positive electrode plane portion A1 and/or the positive electrode of the positive electrode pole piece 1. Bending portion A2.
  • the protrusion S1 on the negative electrode tab 2 may be distributed on the negative plane portion B1 and/or the negative electrode of the negative electrode tab 2. Bending portion B2.
  • the battery cells according to the invention are used in lithium ion batteries and are exemplified as examples and comparative examples and test results.
  • positive electrode sheet 1 positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried.
  • NMP N-methyl-2-pyrrolidone
  • a special roll is used to press a circular protrusion S1 with a diameter of 2 mm at the winding turn of the pole piece, and the protrusion S1 at the winding turn is distributed in a matrix (the winding of the protrusion S1 is set at this time)
  • the turning point is the convex concentrated area T, and the plurality of convex concentrated areas T are intermittently arranged), and all the protrusions S1 on the entire pole piece are arranged in a batch matrix.
  • the protrusion S1 has a distribution density of 3/cm 2 and the protrusion S1 has a height of 12 ⁇ m, and then die-cut and slit to obtain a positive electrode sheet 1 to be wound having a thickness of 115 ⁇ m.
  • negative electrode sheet 2 the negative electrode active material graphite, conductive agent acetylene black, thickener sodium carboxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) by mass ratio 96:2:1:1
  • CMC carboxymethyl cellulose
  • SBR binder styrene butadiene rubber
  • Preparation of separator using polyethylene microporous film as porous separator substrate; mixing inorganic alumina powder, polyvinyl pyrrolidone and acetone solvent into a slurry by weight ratio of 3:1.5:5.5, The slurry is applied to one side of the substrate and dried and slit to form a separator.
  • Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is 1:2:1) , to get the required electrolyte.
  • Preparation of lithium ion battery The positive electrode sheet 1 provided with the protrusion S1 is wound up with the negative electrode pole piece 2 and the separator to obtain a battery core, and then subjected to processes such as encapsulation, liquid injection, chemical conversion, and exhaust. Get a lithium-ion battery.
  • Embodiment 1 The difference from Embodiment 1 is that the negative electrode tab 2 is provided with a projection S1.
  • positive electrode sheet 1 positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried. Cold pressing, die cutting, and slitting are performed to form a positive electrode of a lithium ion battery.
  • NMP N-methyl-2-pyrrolidone
  • negative electrode sheet 2 the negative electrode active material graphite, conductive agent acetylene black, thickener sodium carboxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) by mass ratio 96:2:1:1
  • CMC carboxymethyl cellulose
  • SBR binder styrene butadiene rubber
  • the circular protrusion S1 having a diameter of 2 mm, the protrusions S1 at the winding turn are distributed in a matrix, and all the protrusions S1 on the entire pole piece are distributed in a matrix.
  • the protrusion S1 has a distribution density of 6/cm 2 and the height of the protrusion S1 is 50 ⁇ m, and then die-cutting and striping are performed to obtain a negative electrode tab 2 to be wound.
  • Embodiment 2 The difference from Embodiment 2 is that the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 2 mm, the distribution density of the projection S1 is 12/cm 2 , and the height of the projection S1 is 80 ⁇ m. .
  • the difference from the embodiment 2 is that the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 4 mm, the distribution density of the projection S1 is 4/cm 2 , and the height of the projection S1 is 120 ⁇ m. .
  • the protrusions S1 disposed on the negative electrode tab 2 are distributed over the entire pole piece surface, that is, all the protrusions S1 on the entire pole piece are distributed in a continuous matrix, and the diameter of the circular protrusion S1 is 6mm, the distribution density of the protrusion S1 is 2/cm 2 , and the height of the protrusion S1 is 160 um.
  • the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 9 mm
  • the distribution density of the projection S1 is 1/cm 2
  • the height of the projection S1 is 200 ⁇ m. .
  • Embodiment 2 The difference from Embodiment 2 is that the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 2 mm, the distribution density of the projection S1 is 12/cm 2 , and the height of the projection S1 is 120 ⁇ m. .
  • the protrusions S1 disposed on the negative electrode tab 2 are distributed over the entire pole piece surface, that is, all the protrusions S1 on the entire pole piece are distributed in a continuous matrix, and the diameter of the circular protrusion S1 is 2 mm, the distribution density of the protrusion S1 is 12 pieces/cm 2 , and the height of the protrusion S1 is 120 um. .
  • Embodiment 1 The difference from Embodiment 1 is that the projection S1 is also provided at the winding turn of the negative electrode tab 2.
  • positive electrode sheet 1 positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried.
  • NMP N-methyl-2-pyrrolidone
  • the protrusion S1 at the winding turn is distributed in a matrix, and all the protrusions S1 on the entire pole piece are in a batch matrix. distributed.
  • the protrusion S1 has a distribution density of 12/cm 2 and the protrusion S1 has a height of 80 ⁇ m, and then die-cut and slit to obtain a positive electrode sheet 1 to be wound having a thickness of 115 ⁇ m.
  • negative electrode sheet 2 the negative electrode active material graphite, conductive agent acetylene black, thickener sodium carboxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) by mass ratio 96:2:1:1
  • CMC carboxymethyl cellulose
  • SBR binder styrene butadiene rubber
  • the circular protrusion S1 having a diameter of 2 mm is pressed, and the protrusions S1 at the winding turn are distributed in a matrix, and all the protrusions S1 on the entire pole piece are distributed in a matrix.
  • the projection S1 has a distribution density of 12/cm 2 and the height of the projection S1 is 80 ⁇ m, and then die-cutting and slitting to obtain a negative electrode tab 2 to be wound having a thickness of 115 ⁇ m.
  • the bump S1 is provided on the entire surface of the positive electrode tab 1 and the negative electrode tab 2.
  • the protrusions S1 on the positive electrode tab 1 and the negative electrode tab 2 are all in a continuous matrix distribution, and the protrusion S1 has a diameter of 2 mm, a distribution density of 12/cm 2 , and a height of 65 ⁇ m.
  • the difference from the embodiment 2 is that the projections S1 provided at the winding turns of the negative electrode tab 2 are distributed in a long rectangular shape, and all the projections S1 on the entire pole piece are distributed in an intermittent rectangular shape.
  • the projection of the projection S1 penetrates the entire width of the negative electrode tab 2 and the angle ⁇ between the extending direction of each projection S1 and the width direction W of the negative electrode tab 2 is 15°, the height of the projection S1 is 120 ⁇ m, and the width of the projection rectangle It is 2mm and the interval is 5mm.
  • the difference from the embodiment 11 is that the protrusions S1 disposed on the entire surface of the negative electrode tab 2 are distributed in a long arc shape, and all the protrusions S1 on the entire pole piece are continuously arcuately distributed.
  • the projection of the projection S1 penetrates the entire width of the negative electrode tab 2 and the angle ⁇ between the extending direction of each projection S1 and the width direction W of the negative electrode tab 2 is 20°, the height of the projection S1 is 120 ⁇ m, and the width of the projection rectangle It is 2mm and the interval is 12mm.
  • the protrusion S1 is simultaneously disposed at the winding turn of the positive pole piece 1 and the negative pole piece 2, and all the protrusions S1 on the entire pole piece are intermittently distributed in a long strip shape, and the protrusion S1
  • the projection penetrates the entire width of the pole piece and has a mean of 30°, the height of the protrusion S1 is 65 ⁇ m, the width of the projected rectangle is 4 mm, and the interval is 10 mm.
  • the protrusions S1 are simultaneously disposed on the entire surface of the positive electrode tab 1 and the negative electrode tab 2, and all the protrusions S1 on the entire pole piece are continuously arcuately distributed, and the projection of the protrusion S1 is projected. Throughout the entire width of the pole piece and the ⁇ is 0°, the height of the protrusion S1 is 120 um, the width of the projection rectangle is 8 mm, and the interval is 8 mm.
  • positive electrode sheet 1 positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried. Cold pressing, die cutting, and slitting were performed to form a positive electrode tab 1 of a lithium ion battery having a thickness of 115 um.
  • NMP N-methyl-2-pyrrolidone
  • the negative electrode tab 2 Preparation of the negative electrode tab 2: the negative electrode active material graphite, the conductive agent acetylene black, the thickener sodium carboxymethyl cellulose (CMC), the binder styrene butadiene rubber (SBR) by weight ratio 96:2:1:1
  • the mixture is uniformly mixed and added to the solvent water to prepare a negative electrode slurry; the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, dried, and then subjected to cold pressing, die cutting, and slitting to directly form a lithium ion having a thickness of 115 um. Battery negative plate.
  • a polyethylene microporous film is selected as the porous separator substrate; the alumina powder, the polyvinylpyrrolidone, and the acetone solvent are uniformly mixed in a weight ratio of 3:1.5:5.5 to form a slurry.
  • the slurry is coated on one side of the substrate and dried and slit to obtain a separator.
  • Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is 1:2:1) , to get the required electrolyte.
  • Preparation of a lithium ion battery The positive electrode sheet 1, the negative electrode sheet 2, and the separator are wound to obtain a battery cell, and then subjected to a process of encapsulation, liquid injection, formation, and exhaust to obtain a lithium ion battery.
  • Capacity retention rate in order to characterize the influence of the battery cell of the present invention on the positive electrode pole piece 1 in a lithium ion battery and the positive electrode pole piece 1 of the lithium ion battery in the comparative example on the cycle life and safety performance of the battery, the electricity of the present invention
  • the cells of the lithium ion battery in the core and the comparative example were subjected to a cycle of 60 ° C and 2 C / 3 C for 800 times, respectively, and the capacity retention rate thereof was examined.
  • the voltage range is 2.8V to 4.2V
  • charging at a rate of 2C discharging at a rate of 3C
  • the cycle capacity retention rate is the 3C discharge capacity of the 800th cycle relative to the second 3C discharge capacity. proportion.
  • the battery cell of the present invention is used for the influence of the positive electrode tab 1 in a lithium ion battery and the positive electrode tab 1 of a lithium ion battery in a comparative example on the infiltration speed of the electrolyte, by immersing the battery core in electrolysis After the liquid is taken out for 5 hours, it is placed at a drying time of 90 ° C to be characterized. It is judged whether the cell is dried by judging whether the internal resistance of the cell is greater than 100 M ⁇ (for example, drying is greater than 100 M ⁇ ).
  • Table 1 shows the detection results of the respective examples and comparative examples. From the test result data of Table 1, it can be seen that:
  • the pole piece with the convex S1 protrusion is pressed, and whether it is a matrix distribution or a stripe distribution, it can significantly improve the cycle performance of the battery while effectively improving the electrolyte wettability.
  • the battery of the present invention has the following advantages when used in a lithium ion battery as compared with the prior art:
  • the protrusions S1 on the pole piece can form an interlayer gap, which is beneficial to increase the penetration of the electrolyte inside the battery core, and is beneficial to the infiltration of the core electrolyte, especially the core winding which can effectively improve the concentration of the expansion force.
  • the electrolyte wetting property of the pole piece at the turn is beneficial to ensured during the charging and discharging process, thereby improving the cycle life and storage performance of the cell.
  • the protrusion S1 on the pole piece can form an interlayer gap, and a support skeleton is formed between the pole piece and the isolation film through the undulating structure, so that there is a certain buffer gap between the pole piece and the isolation film, and the expansion stress concentration is given to the circulation process.
  • the pole piece creates a buffer space that effectively releases the expansion of the pole piece during the cycle
  • the expansion stress which significantly reduces the distortion caused by the expansion of the pole piece, prevents the battery short circuit caused by the breakage of the pole piece and the safety accident caused, and improves the safety performance and cycle life of the lithium ion battery.

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Abstract

The present invention provides a pole piece and an electrochemical cell. The pole piece comprises: a current collector; and an active substance layer, coated on the surface of the current collector. The pole piece has a plurality of protrusions. All the protrusions are formed by the current collector and the active substance layer on the surface of the current collector protruding outward from a side of the pole piece in the thickness direction, and all the protrusions are formed on the same side of the pole piece in the thickness direction. In the pole piece according to the present invention, because the pole piece has the plurality of protrusions formed by the current collector and the active substance layer on the surface of the current collector protruding outward from the side of the pole piece in the thickness direction, when the pole piece is applied to the electrochemical cell, the plurality of protrusions can provide buffer space for the continuously expanded pole piece to release the expansion stress of the pole piece, so as to improve the safety performance and cycle performance of the electrochemical cell.

Description

极片及电芯Pole piece and cell 技术领域Technical field
本发明涉及电池领域，尤其涉及一种极片及电芯。The present invention relates to the field of batteries, and in particular to a pole piece and a battery core.
背景技术Background technique
目前，锂离子电池作为动力电池已获得广泛应用。随着市场竞争日益激烈，各大锂离子电池公司都针对动力锂离子电池的性能和制造工艺进行了不断探索和改进。电芯作为锂离子电池的核心部件，通常采用叠片和卷绕两种方式，其中，卷绕方式因工艺简单、装配效率高、易于自动化而被广大锂离子电池制造企业采用。At present, lithium ion batteries have been widely used as power batteries. With the increasingly fierce market competition, major lithium-ion battery companies have continuously explored and improved the performance and manufacturing process of power lithium-ion batteries. As the core component of lithium-ion battery, the battery core is usually laminated and wound. The winding method is adopted by the majority of lithium-ion battery manufacturers due to the simple process, high assembly efficiency and easy automation.
在锂离子电池的应用过程中，安全性能和循环寿命至关重要。众所周知，传统的卷绕式锂离子电池，通常对极片进行压实，以提高电芯正极的填充密度，此时，辊压而成的极片会变得很脆。锂离子电池的极片在充放电过程中，会因活性物质不同的脱锂或嵌锂状态而发生体积膨胀。极片的膨胀必然导致卷绕式锂离子电池电芯层间产生内应力，如果产生的膨胀应力得不到有效释放，当循环达到一定程度时，将会导致卷绕式电芯的扭曲变形，尤其在内应力最为集中的卷绕后转弯处极片，更易发生，而极片的拉伸变形可能引发锂离子电池内短等安全隐患。此外，不断挤压的极片使得循环后期极片层间间隙锁死而导致电解液浸润性变差，而电解液的浸润不足会导致后期的循环性能恶化。Safety performance and cycle life are critical in the application of lithium-ion batteries. It is well known that a conventional wound lithium ion battery usually compacts a pole piece to increase the packing density of the positive electrode of the battery cell. At this time, the rolled pole piece becomes very brittle. During the charging and discharging process, the pole piece of the lithium ion battery may expand in volume due to the delithiation or lithium intercalation state of the active material. The expansion of the pole piece inevitably leads to internal stress between the layers of the wound lithium ion battery cell. If the generated expansion stress is not effectively released, when the cycle reaches a certain level, the twisted deformation of the wound cell will be caused. Especially in the most concentrated inner stress, the pole piece after winding is more likely to occur, and the tensile deformation of the pole piece may cause short safety hazards in the lithium ion battery. In addition, the continuously extruded pole piece causes the interlayer gap between the poles to be locked in the late cycle, resulting in poor electrolyte wettability, and insufficient electrolyte infiltration leads to deterioration of the cycle performance in the later stage.
发明内容Summary of the invention
鉴于背景技术中存在的问题，本发明的目的在于提供一种极片及电芯，当极片应用于电芯时提高了电芯的安全性能和循环性能。In view of the problems in the prior art, it is an object of the present invention to provide a pole piece and a battery core which improve the safety performance and cycle performance of the battery core when the pole piece is applied to the battery core.
为了实现上述目的，在第一方面，本发明提供了一种极片，其包括：集流体；以及活性物质层，涂覆在集流体的表面上。极片具有多个凸起，所有凸起均由集流体和集流体表面上的活性物质层一起沿极片的厚度方向的一 侧向外凸出而成，且所有凸起形成于极片的厚度方向的同一侧。In order to achieve the above object, in a first aspect, the present invention provides a pole piece comprising: a current collector; and an active material layer coated on a surface of the current collector. The pole piece has a plurality of protrusions, all of which are formed by the current collector and the active material layer on the surface of the current collector along the thickness direction of the pole piece The sides are convex outward, and all the protrusions are formed on the same side in the thickness direction of the pole piece.
在第二方面，本发明提供了一种电芯，其包括：正极极片、负极极片以及隔离膜。In a second aspect, the present invention provides a battery cell comprising: a positive electrode tab, a negative pole tab, and a separator.
正极极片包括：正极集流体；以及正极活性物质层，涂覆在正极集流体的表面上。负极极片包括：负极集流体；以及负极活性物质层，涂覆在负极集流体的表面。隔离膜位于正极极片与负极极片之间。其中，正极极片和负极极片中的至少一个采用本发明第一方面所述的极片。The positive electrode tab includes: a cathode current collector; and a cathode active material layer coated on a surface of the cathode current collector. The negative electrode tab includes: a negative electrode current collector; and a negative electrode active material layer coated on a surface of the negative electrode current collector. The separator is located between the positive electrode tab and the negative electrode tab. Wherein at least one of the positive electrode tab and the negative electrode tab employs the pole piece according to the first aspect of the invention.
本发明的有益效果如下：The beneficial effects of the present invention are as follows:
在根据本发明的极片中，由于极片具有由集流体和集流体表面上的活性物质层一起沿极片的厚度方向的一侧向外凸出而成的多个凸起，当极片应用于电芯时，多个凸起能够给不断膨胀的极片创造缓冲空间以释放极片的膨胀应力，从而提高了电芯的安全性能和循环性能。In the pole piece according to the present invention, since the pole piece has a plurality of protrusions which are outwardly convex from one side of the thickness direction of the pole piece by the current collector layer on the surface of the current collector and the current collector, the pole piece When applied to a battery cell, a plurality of protrusions can create a buffer space for the continuously expanding pole piece to release the expansion stress of the pole piece, thereby improving the safety performance and cycle performance of the battery core.
附图说明DRAWINGS
图1是根据本发明的极片在一实施例中的俯视图；Figure 1 is a plan view of an electrode piece in accordance with an embodiment of the present invention;
图2是图1的主视图；Figure 2 is a front elevational view of Figure 1;
图3是图2中圆圈部分的放大图；Figure 3 is an enlarged view of a circled portion of Figure 2;
图4是根据本发明的极片在另一实施例中的俯视图；Figure 4 is a plan view of a pole piece in accordance with another embodiment of the present invention;
图5是图4的主视图；Figure 5 is a front elevational view of Figure 4;
图6是图5中圆圈部分的放大图；Figure 6 is an enlarged view of a circled portion in Figure 5;
图7是根据本发明的极片在又一实施例中的俯视图；Figure 7 is a plan view of a pole piece in accordance with another embodiment of the present invention;
图8是图7的主视图；Figure 8 is a front elevational view of Figure 7;
图9是图8中方框部分的放大图；Figure 9 is an enlarged view of the block portion of Figure 8;
图10是根据本发明的极片在再一实施例中的俯视图；Figure 10 is a plan view of a pole piece in accordance with another embodiment of the present invention;
图11是图10的主视图；Figure 11 is a front elevational view of Figure 10;
图12是图11中方框部分的放大图；Figure 12 is an enlarged view of the block portion of Figure 11;
图13是图1的变形图；Figure 13 is a deformation view of Figure 1;
图14是图13的主视图；Figure 14 is a front elevational view of Figure 13;
图15是图14中圆圈部分的放大图；Figure 15 is an enlarged view of a circled portion in Figure 14;
图16是根据本发明的电芯在一实施例中的截面图； Figure 16 is a cross-sectional view of an electric cell in accordance with an embodiment of the present invention;
图17是根据本发明的电芯在另一实施例中的截面图。Figure 17 is a cross-sectional view of a battery cell in accordance with another embodiment of the present invention.
其中，附图标记说明如下：Among them, the reference numerals are as follows:
P极片                       12正极活性物质层 P pole piece 12 cathode active material layer
P1集流体                    A1正极平面部P1 current collector A1 positive plane
P2活性物质层                A2正极弯折部P2 active material layer A2 positive electrode bent portion
S凸起集中区                 2负极极片S convex concentrated area 2 negative pole piece
S1凸起                      21负极集流体 S1 bump 21 anode current collector
H厚度方向                   22负极活性物质层 H thickness direction 22 anode active material layer
L长度方向                   B1负极平面部L length direction B1 negative plane
W宽度方向                   B2负极弯折部W width direction B2 negative bend
1正极极片                   3隔离膜1 positive pole piece 3 isolating film
11正极集流体11 positive current collector
具体实施方式detailed description
下面参照附图来详细说明根据本发明的极片及电芯。The pole piece and the battery core according to the present invention will be described in detail below with reference to the accompanying drawings.
首先说明本发明第一方面的极片。First, the pole piece of the first aspect of the invention will be described.
参照图1至图15，根据本发明的极片P包括：集流体P1；以及活性物质层P2，涂覆在集流体P1的表面上。极片P具有多个凸起S1，所有凸起S1均由集流体P1和集流体P1表面上的活性物质层P2一起沿极片P的厚度方向H的一侧向外凸出而成(此时凸起S1的内部为凹坑)，且所有凸起S1形成于极片P的厚度方向H的同一侧。Referring to FIGS. 1 through 15, a pole piece P according to the present invention includes: a current collector P1; and an active material layer P2 coated on a surface of the current collector P1. The pole piece P has a plurality of protrusions S1, and all of the protrusions S1 are formed by the current collector P1 and the active material layer P2 on the surface of the current collector P1 projecting outward along one side of the thickness direction H of the pole piece P (this The inside of the projection S1 is a pit, and all the projections S1 are formed on the same side in the thickness direction H of the pole piece P.
在根据本发明的极片P中，由于极片P具有由集流体P1和集流体P1表面上的活性物质层P2一起沿极片P的厚度方向H的一侧向外凸出而成的多个凸起S1，当极片P应用于电芯时，多个凸起S1能够给不断膨胀的极片P创造缓冲空间以释放极片P的膨胀应力，从而提高了电芯的安全性能和循环性能。In the pole piece P according to the present invention, since the pole piece P has a large amount of the current collector P1 and the active material layer P2 on the surface of the current collector P1, which protrudes outward along one side in the thickness direction H of the pole piece P, The protrusion S1, when the pole piece P is applied to the battery core, the plurality of protrusions S1 can create a buffer space for the continuously expanding pole piece P to release the expansion stress of the pole piece P, thereby improving the safety performance and circulation of the battery element. performance.
根据本发明的极片P，在一实施例中，参照图1、图4和图13，所有凸起S1分布于整个极片P，且所有凸起S1在极片P表面上的投影面积的总和占极片P该表面的总面积的10％-60％，这是因为所有凸起S1在极片P表面 上的投影面积的总和与极片P该表面的总面积的比值若太小达不到缓解极片P的膨胀应力的作用，反之若太大，会带来较大的极片P界面浓差极化风险。According to the pole piece P of the present invention, in an embodiment, referring to Figs. 1, 4 and 13, all the projections S1 are distributed over the entire pole piece P, and the projection areas of all the projections S1 on the surface of the pole piece P are The sum accounts for 10% to 60% of the total area of the surface of the pole piece P, because all the protrusions S1 are on the surface of the pole piece P If the ratio of the sum of the projected areas on the surface of the pole piece P to the total area of the surface of the pole piece P is too small to alleviate the expansion stress of the pole piece P, if it is too large, a large pole piece P interface concentration difference will be brought. Risk of polarization.
在这里补充说明的是，所有凸起S1可以有规则的均匀分布于整个极片P(此为优选的凸起S1的布置方式)，也可以无规则的随机分布于整个极片P。根据本发明的极片P，在一实施例中，参照图7和图10，所有凸起S1形成间隔开的多个凸起集中区T，且各凸起集中区T上的所有凸起S1在该凸起集中区T表面上的投影面积的总和占该凸起集中区T所述表面的总面积的10％-60％，这是因为各凸起集中区T上的所有凸起S1在该凸起集中区T表面上的投影面积的总和与该凸起集中区T所述表面的总面积的比值若太小达不到缓解极片P的膨胀应力的作用，反之若太大，会带来较大的极片P界面浓差极化风险。。It is added here that all the protrusions S1 can be uniformly distributed uniformly over the entire pole piece P (this is the arrangement of the preferred protrusions S1), or can be randomly and randomly distributed throughout the pole piece P. According to the pole piece P of the present invention, in an embodiment, referring to Figs. 7 and 10, all the projections S1 form a plurality of spaced apart convex concentrated regions T, and all the projections S1 on each of the convex concentrated regions T The sum of the projected areas on the surface of the raised concentration area T is 10%-60% of the total area of the surface of the raised concentrated area T, because all the protrusions S1 on each of the raised concentrated areas T are If the ratio of the sum of the projected areas on the surface of the raised concentrated area T to the total area of the surface of the raised concentrated area T is too small to alleviate the expansion stress of the pole piece P, if it is too large, Brings a large pole P interface concentration polarization risk. .
根据本发明的极片P，在一实施例中，凸起S1沿极片P的长度方向L和宽度方向W阵列分布。具体地，参照图1，所有凸起S1沿极片P的长度方向L和宽度方向W阵列分布于整个极片P；参照图7，各凸起集中区T中的所有凸起S1沿极片P的长度方向L和宽度方向W阵列分布于该凸起集中区T。在这里补充说明的是，这种阵列分布的方式适用于体积相对较小且可大致看成为点状结构的凸起S1。此外，由于凸起S1呈阵列分布，使得凸起S1与凸起S1之间存在方向性的传输通道，从而还有利于电解液传输。According to the pole piece P of the present invention, in one embodiment, the projections S1 are distributed in an array along the longitudinal direction L and the width direction W of the pole piece P. Specifically, referring to FIG. 1, all the protrusions S1 are distributed in the entire pole piece P along the longitudinal direction L and the width direction W of the pole piece P; referring to FIG. 7, all the protrusions S1 in each of the protrusion concentration areas T are along the pole piece An array of the longitudinal direction L and the width direction W of P is distributed in the convex concentration region T. It is added here that the manner in which such an array is distributed is applied to the projection S1 which is relatively small in volume and which can be roughly regarded as a dot-like structure. In addition, since the protrusions S1 are distributed in an array, there is a directional transmission path between the protrusions S1 and the protrusions S1, thereby facilitating the electrolyte transfer.
在根据本发明的极片P中，各凸起S1在极片P上的投影形状可为圆形、椭圆形、或多边形。进一步地，多边形可为矩形、三角形或梯形。对应地，各凸起S1的实际立体结构可为球体的一部分、椭球体的一部分、长方体、棱柱、棱台或截锥体。In the pole piece P according to the present invention, the projection shape of each of the projections S1 on the pole piece P may be circular, elliptical, or polygonal. Further, the polygon may be rectangular, triangular or trapezoidal. Correspondingly, the actual three-dimensional structure of each protrusion S1 may be a part of a sphere, a part of an ellipsoid, a rectangular parallelepiped, a prism, a prism or a truncated cone.
根据本发明的极片P，在一实施例中，当各凸起S1在极片P上的投影形状为圆形时，圆形的直径可为2mm～10mm。当各凸起S在极片P上的投影形状为矩形时，矩形的长度可为2mm～10mm，矩形的宽度可为2mm～10mm。According to the pole piece P of the present invention, in an embodiment, when the projection shape of each of the projections S1 on the pole piece P is circular, the diameter of the circular shape may be 2 mm to 10 mm. When the projection shape of each of the protrusions S on the pole piece P is a rectangle, the length of the rectangle may be 2 mm to 10 mm, and the width of the rectangle may be 2 mm to 10 mm.
根据本发明的极片P，在一实施例中，各凸起S1沿极片P的宽度方向W延伸而横跨极片P的整个宽度，即各凸起S1宽度等于极片P的宽，而此时各凸起S1沿极片P的长度方向L上跨度可为1mm～10mm，优选地各凸起S1沿极片P的长度方向L上跨度为3mm～6mm。具体地，参照图4，所有凸起S1沿极片P的长度方向L间隔分布于整个极片P；参照图10，各凸起集 中区T中的所有凸起S1沿极片P的长度方向L间隔分布于该凸起集中区T中。According to the pole piece P of the present invention, in an embodiment, each of the protrusions S1 extends along the width direction W of the pole piece P across the entire width of the pole piece P, that is, the width of each of the protrusions S1 is equal to the width of the pole piece P, In this case, the span S1 may span from 1 mm to 10 mm in the longitudinal direction L of the pole piece P. Preferably, each of the protrusions S1 has a span of 3 mm to 6 mm along the longitudinal direction L of the pole piece P. Specifically, referring to FIG. 4, all the protrusions S1 are distributed over the entire pole piece P along the length direction L of the pole piece P; referring to FIG. 10, each convex set All the projections S1 in the middle portion T are distributed in the projection concentration region T along the length direction L of the pole piece P.
在一实施例中，参照图13，各凸起S1相对极片P的宽度方向W倾斜延伸而斜跨极片P的整个宽度，此时各凸起S1沿与凸起S1的延伸方向垂直的方向上跨度可为1mm～10mm，优选地，各凸起S1沿与凸起S1的延伸方向垂直的方向上跨度为3mm～6mm。In an embodiment, referring to FIG. 13, each of the protrusions S1 extends obliquely with respect to the width direction W of the pole piece P and obliquely across the entire width of the pole piece P, and at this time, each of the protrusions S1 is perpendicular to the extending direction of the protrusion S1. The span in the direction may be 1 mm to 10 mm, and preferably, each of the protrusions S1 has a span of 3 mm to 6 mm in a direction perpendicular to the extending direction of the protrusion S1.
在这里补充说明的是，对于上述不同形状的单个凸起S1的尺寸大小需要合理设置，因为凸起S1的尺寸若太小，则极片P的层间间隙小，达不到缓解极片P的膨胀应力的作用，反之若太大，压制时对极片P本身容易造成损伤。此外，上述给出的凸起S1的尺寸范围只是在实际生产中优选的尺寸大小，当然不仅限如此，可根据具体情况适当改变。It should be added here that the size of the single protrusion S1 of different shapes described above needs to be properly set. Because the size of the protrusion S1 is too small, the interlayer gap of the pole piece P is small, and the relief piece P cannot be achieved. The effect of the expansion stress, if it is too large, causes damage to the pole piece P itself when pressed. Further, the size range of the projection S1 given above is only a preferred size in actual production, and it is of course not limited thereto, and may be appropriately changed depending on the specific circumstances.
在一实施例中，参照图13，各凸起S1的延伸方向与极片P的宽度方向W的夹角ψ不大于30度。In an embodiment, referring to FIG. 13, the angle ψ between the extending direction of each of the protrusions S1 and the width direction W of the pole piece P is not more than 30 degrees.
根据本发明的极片P，在一实施例中，凸起S1在垂直于极片P表面的平面上的截面形状为弧形(如图3、图9和图15所示)或多线段构成的折线形(如图6和图12所示)。According to the pole piece P of the present invention, in an embodiment, the cross-sectional shape of the projection S1 on a plane perpendicular to the surface of the pole piece P is curved (as shown in Figs. 3, 9 and 15) or a multi-line segment. The line shape (as shown in Figures 6 and 12).
在根据本发明的极片P中，各凸起S1的高度与极片P的厚度之比可为0.05～1.5。进一步地，各凸起S1的高度与极片P的厚度之比可为0.05～0.8，更进一步地，各凸起S1的高度与极片P的厚度之比可为0.3～0.7。在这里补充说明的是，相关附图中示意出的各凸起S1的高度与极片P的厚度之间的比例大小，不代表实际产品中的各凸起S1的高度与极片P的厚度之间的比例大小，仅仅是为了清楚地示意出各凸起S1的结构。In the pole piece P according to the present invention, the ratio of the height of each of the projections S1 to the thickness of the pole piece P may be 0.05 to 1.5. Further, the ratio of the height of each of the protrusions S1 to the thickness of the pole piece P may be 0.05 to 0.8, and further, the ratio of the height of each of the protrusions S1 to the thickness of the pole piece P may be 0.3 to 0.7. It is added here that the ratio between the height of each of the protrusions S1 and the thickness of the pole piece P illustrated in the relevant drawings does not represent the height of each of the protrusions S1 and the thickness of the pole piece P in the actual product. The ratio between the dimensions is merely to clearly illustrate the structure of each of the projections S1.
在根据本发明的极片P中，极片P的厚度可为90um～130um。优选地，极片P的厚度可为115um。In the pole piece P according to the present invention, the pole piece P may have a thickness of 90 um to 130 um. Preferably, the pole piece P may have a thickness of 115 um.
在根据本发明的极片P中，极片P上的各凸起S1可由压辊压制而成。In the pole piece P according to the present invention, each of the projections S1 on the pole piece P can be pressed by a press roll.
其次说明根据本发明第二方面的电芯。Next, a battery cell according to a second aspect of the invention will be described.
参照图16和图17，根据本发明的电芯包括：正极极片1、负极极片2以及隔离膜3。Referring to FIGS. 16 and 17, the battery cell according to the present invention includes a positive electrode tab 1, a negative electrode tab 2, and a separator 3.
正极极片1包括：正极集流体11；以及正极活性物质层12，涂覆在正 极集流体11的表面上。负极极片2包括：负极集流体21；以及负极活性物质层22，涂覆在负极集流体21的表面。隔离膜3位于正极极片1与负极极片2之间。其中，正极极片1和负极极片2中的至少一个采用本发明第一方面所述的极片P。The positive electrode tab 1 includes: a cathode current collector 11; and a cathode active material layer 12 coated on the positive electrode On the surface of the pole current collector 11. The negative electrode tab 2 includes: a negative electrode current collector 21; and a negative electrode active material layer 22 coated on the surface of the negative electrode current collector 21. The separator 3 is located between the positive electrode tab 1 and the negative electrode tab 2. Among them, at least one of the positive electrode tab 1 and the negative electrode tab 2 employs the pole piece P according to the first aspect of the invention.
在根据本发明的电芯中，由于正极极片1和负极极片2中的至少一个采用本发明第一方面所述的极片P，极片P中的多个凸起S1能够给不断膨胀的电芯创造缓冲空间以释放电芯的膨胀应力，从而提高了电芯的安全性能和循环性能。In the battery according to the present invention, since at least one of the positive electrode tab 1 and the negative electrode tab 2 employs the pole piece P according to the first aspect of the invention, the plurality of projections S1 in the pole piece P can be continuously expanded The cells create a buffer space to release the expansion stress of the cell, thereby improving the safety and cycle performance of the cell.
根据本发明的电芯，在一实施例中，仅正极极片1采用本发明第一方面所述的极片P。According to the battery cell of the present invention, in one embodiment, only the positive electrode tab 1 employs the pole piece P of the first aspect of the invention.
根据本发明的电芯，在一实施例中，参照图16，仅负极极片2采用本发明第一方面所述的极片P。这是因为当正极极片1的压实密度较高时，正极极片1比较脆，在压制过程容易断裂，这时可选择将凸起S1设置在压实密度低、韧性好的负极极片2上。According to the battery cell of the present invention, in an embodiment, referring to Fig. 16, only the negative electrode tab 2 employs the pole piece P of the first aspect of the invention. This is because when the compact density of the positive electrode tab 1 is high, the positive electrode tab 1 is relatively brittle and is easily broken during the pressing process. In this case, the projection S1 can be selectively disposed on the negative pole piece having low compacting density and good toughness. 2 on.
根据本发明的电芯，在一实施例中，参照图17，正极极片1和负极极片2均采用本发明第一方面所述的极片P。在这里补充说明的是，由于正极极片1和负极极片2上均设置有凸起S1，则正极极片1和负极极片2上的凸起S1可一起为不断膨胀的电芯创造缓冲空间以释放电芯的膨胀应力，从而正极极片1和负极极片2上的凸起S1的高度都无需设置太高，进而减小了凸起S1在压制形成过程中对正极极片1和负极极片2的损伤。According to the battery cell of the present invention, in an embodiment, referring to Fig. 17, the positive electrode tab 1 and the negative electrode tab 2 each employ the pole piece P of the first aspect of the invention. It is additionally noted that since the positive electrode tab 1 and the negative electrode tab 2 are each provided with a projection S1, the projection S1 on the positive pole tab 1 and the negative pole tab 2 can together create a buffer for the continuously expanding cell. The space is to release the expansion stress of the cell, so that the heights of the protrusions S1 on the positive electrode tab 1 and the negative electrode tab 2 need not be set too high, thereby reducing the protrusion S1 during the press forming process to the positive pole tab 1 and Damage to the negative electrode tab 2.
在一实施例中，电芯可为叠片式电芯。In an embodiment, the cells may be laminated cells.
在一实施例中，电芯为卷绕式电芯。其中，正极极片1在卷绕时形成有正极平面部A1和正极弯折部A2(即卷绕转弯处)，负极极片2在卷绕时形成有负极平面部B1和负极弯折部B2(即卷绕转弯处)。In an embodiment, the battery cells are wound cells. The positive electrode tab 1 is formed with a positive electrode flat portion A1 and a positive electrode bent portion A2 (ie, a winding turn) at the time of winding, and the negative electrode tab 2 is formed with a negative electrode flat portion B1 and a negative electrode bent portion B2 at the time of winding. (ie winding the turn).
在一实施例中，当正极极片1采用本发明第一方面所述的极片P时，正极极片1上的凸起S1可分布于正极极片1的正极平面部A1和/或正极弯折部A2。In an embodiment, when the positive pole piece 1 adopts the pole piece P according to the first aspect of the invention, the protrusion S1 on the positive electrode pole piece 1 may be distributed on the positive electrode plane portion A1 and/or the positive electrode of the positive electrode pole piece 1. Bending portion A2.
在一实施例中，当负极极片2采用本发明第一方面所述的极片P时，负极极片2上的凸起S1可分布于负极极片2的负极平面部B1和/或负极弯折部B2。 In an embodiment, when the negative electrode tab 2 is the pole piece P according to the first aspect of the invention, the protrusion S1 on the negative electrode tab 2 may be distributed on the negative plane portion B1 and/or the negative electrode of the negative electrode tab 2. Bending portion B2.
最后补充说明根据本发明的电芯用于锂离子电池并作为举例的实施例和对比例及测试结果。Finally, the battery cells according to the invention are used in lithium ion batteries and are exemplified as examples and comparative examples and test results.
实施例1Example 1
正极极片1的制备：将正极活性物质Li(Ni1/3Co1/3Mn1/3)O2、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF)按质量比97：2：1混合均匀并加入到作为溶剂的N-甲基-2-吡咯烷酮(NMP)中，制成具有一定粘度的正极浆料；将正极浆料均匀涂布在正极集流体铝箔上，烘干后冷压，压制过程中用特制辊在极片的卷绕转弯处压制直径为2mm的圆形凸起S1，卷绕转弯处的凸起S1呈矩阵分布(此时设置有凸起S1的卷绕转弯处为凸起集中区T，而多个凸起集中区T间歇布置)，整个极片上的所有凸起S1呈间歇矩阵分布。其凸起S1的分布密度为3个/cm2，凸起S1高度为12um，然后进行模切、分条，得到厚度为115um的待卷绕正极极片1。Preparation of positive electrode sheet 1 : positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried. Cold pressing, during the pressing process, a special roll is used to press a circular protrusion S1 with a diameter of 2 mm at the winding turn of the pole piece, and the protrusion S1 at the winding turn is distributed in a matrix (the winding of the protrusion S1 is set at this time) The turning point is the convex concentrated area T, and the plurality of convex concentrated areas T are intermittently arranged), and all the protrusions S1 on the entire pole piece are arranged in a batch matrix. The protrusion S1 has a distribution density of 3/cm 2 and the protrusion S1 has a height of 12 μm, and then die-cut and slit to obtain a positive electrode sheet 1 to be wound having a thickness of 115 μm.
负极极片2的制备：将负极活性物质石墨、导电剂乙炔黑、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比96：2：1：1混合均匀并加入到溶剂水中，制成负极浆料；将负极浆料均匀涂布在负极集流体铜箔上，烘干后进行冷压、模切、分条，做成厚度为115um的锂离子电池负极极片2。Preparation of negative electrode sheet 2: the negative electrode active material graphite, conductive agent acetylene black, thickener sodium carboxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) by mass ratio 96:2:1:1 The mixture is uniformly mixed and added to the solvent water to prepare a negative electrode slurry; the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, dried, and then subjected to cold pressing, die cutting, and slitting to form a lithium ion having a thickness of 115 μm. Battery negative pole piece 2.
隔离膜的制备：选用聚乙烯微孔薄膜作为多孔隔离膜基材；将无机三氧化铝粉末、聚乙烯呲咯烷酮、丙酮溶剂按重量比3：1.5：5.5混合均匀制成浆料，将浆料涂布于基材的一面并烘干并分条，制成隔离膜。Preparation of separator: using polyethylene microporous film as porous separator substrate; mixing inorganic alumina powder, polyvinyl pyrrolidone and acetone solvent into a slurry by weight ratio of 3:1.5:5.5, The slurry is applied to one side of the substrate and dried and slit to form a separator.
电解液的制备：将六氟磷酸锂溶解于碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂中(碳酸乙烯酯、碳酸二甲酯及碳酸甲乙酯的体积比为1：2：1)，得到所需电解液。Preparation of electrolyte: Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is 1:2:1) , to get the required electrolyte.
锂离子电池的制备：将上述设有凸起S1的正极极片1，同负极极片2以及隔离膜进行卷绕，得到电芯，然后经过封装、注液、化成、排气等工序，制得锂离子电池。Preparation of lithium ion battery: The positive electrode sheet 1 provided with the protrusion S1 is wound up with the negative electrode pole piece 2 and the separator to obtain a battery core, and then subjected to processes such as encapsulation, liquid injection, chemical conversion, and exhaust. Get a lithium-ion battery.
实施例2Example 2
与实施例1的不同之处：负极极片2设置有凸起S1。 The difference from Embodiment 1 is that the negative electrode tab 2 is provided with a projection S1.
正极极片1的制备：将正极活性物质Li(Ni1/3Co1/3Mn1/3)O2、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF)按质量比97：2：1混合均匀并加入到作为溶剂的N-甲基-2-吡咯烷酮(NMP)中，制成具有一定粘度的正极浆料；将正极浆料均匀涂布在正极集流体铝箔上，烘干后进行冷压、模切、分条，做成锂离子电池正极片。Preparation of positive electrode sheet 1 : positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried. Cold pressing, die cutting, and slitting are performed to form a positive electrode of a lithium ion battery.
负极极片2的制备：将负极活性物质石墨、导电剂乙炔黑、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比96：2：1：1混合均匀并加入到溶剂水中，制成负极浆料；将负极浆料均匀涂布在负极集流体铜箔上，烘干后冷压，压制过程中用特制辊在极片的卷绕转弯处压制直径为2mm的圆形凸起S1，卷绕转弯处的凸起S1呈矩阵分布，整个极片上的所有凸起S1呈间歇矩阵分布。其凸起S1的分布密度为6个/cm2，凸起S1的高度为50um，然后进行模切、分条，得到待卷绕负极极片2。Preparation of negative electrode sheet 2: the negative electrode active material graphite, conductive agent acetylene black, thickener sodium carboxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) by mass ratio 96:2:1:1 The mixture is uniformly mixed and added to the solvent water to prepare a negative electrode slurry; the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, dried and then cold pressed, and the special roll is pressed in the winding turn of the pole piece during the pressing process. The circular protrusion S1 having a diameter of 2 mm, the protrusions S1 at the winding turn are distributed in a matrix, and all the protrusions S1 on the entire pole piece are distributed in a matrix. The protrusion S1 has a distribution density of 6/cm 2 and the height of the protrusion S1 is 50 μm, and then die-cutting and striping are performed to obtain a negative electrode tab 2 to be wound.
其余的制备步骤同实施例1，这里不在赘述。The rest of the preparation steps are the same as in the first embodiment, and are not described here.
实施例3Example 3
与实施例2的不同之处：设置于负极极片2的卷绕转弯处的凸起S1的直径为2mm，其凸起S1的分布密度为12个/cm2，凸起S1的高度为80um。The difference from Embodiment 2 is that the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 2 mm, the distribution density of the projection S1 is 12/cm 2 , and the height of the projection S1 is 80 μm. .
实施例4Example 4
与实施例2的不同之处：设置于负极极片2的卷绕转弯处的凸起S1的直径为4mm，其凸起S1的分布密度为4个/cm2，凸起S1的高度为120um。The difference from the embodiment 2 is that the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 4 mm, the distribution density of the projection S1 is 4/cm 2 , and the height of the projection S1 is 120 μm. .
实施例5Example 5
与实施例2的不同之处：设置于负极极片2上的凸起S1分布于整个极片面上，即整个极片上的所有凸起S1呈连续矩阵分布，其圆形凸起S1的直径为6mm，其凸起S1的分布密度为2个/cm2，凸起S1的高度为160um。The difference from the embodiment 2 is that the protrusions S1 disposed on the negative electrode tab 2 are distributed over the entire pole piece surface, that is, all the protrusions S1 on the entire pole piece are distributed in a continuous matrix, and the diameter of the circular protrusion S1 is 6mm, the distribution density of the protrusion S1 is 2/cm 2 , and the height of the protrusion S1 is 160 um.
实施例6Example 6
与实施例2的不同之处：设置于负极极片2的卷绕转弯处的凸起S1的直径为9mm，其凸起S1的分布密度为1个/cm2，凸起S1的高度为200um。 The difference from the embodiment 2 is that the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 9 mm, the distribution density of the projection S1 is 1/cm 2 , and the height of the projection S1 is 200 μm. .
实施例7Example 7
与实施例2的不同之处：设置于负极极片2的卷绕转弯处的凸起S1的直径为2mm，其凸起S1的分布密度为12个/cm2，凸起S1的高度为120um。The difference from Embodiment 2 is that the diameter of the projection S1 provided at the winding turn of the negative electrode tab 2 is 2 mm, the distribution density of the projection S1 is 12/cm 2 , and the height of the projection S1 is 120 μm. .
实施例8Example 8
与实施例5的不同之处：设置于负极极片2上的凸起S1分布于整个极片面上，即整个极片上的所有凸起S1呈连续矩阵分布，其圆形凸起S1的直径为2mm，其凸起S1的分布密度为12个/cm2，凸起S1的高度为120um。。The difference from the embodiment 5 is that the protrusions S1 disposed on the negative electrode tab 2 are distributed over the entire pole piece surface, that is, all the protrusions S1 on the entire pole piece are distributed in a continuous matrix, and the diameter of the circular protrusion S1 is 2 mm, the distribution density of the protrusion S1 is 12 pieces/cm 2 , and the height of the protrusion S1 is 120 um. .
实施例9Example 9
与实施例1的不同之处：在负极极片2的卷绕转弯处同样设置了凸起S1。The difference from Embodiment 1 is that the projection S1 is also provided at the winding turn of the negative electrode tab 2.
正极极片1的制备：将正极活性物质Li(Ni1/3Co1/3Mn1/3)O2、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF)按质量比97：2：1混合均匀并加入到作为溶剂的N-甲基-2-吡咯烷酮(NMP)中，制成具有一定粘度的正极浆料；将正极浆料均匀涂布在正极集流体铝箔上，烘干后冷压，用特制辊在正极极片1的卷绕转弯处压制直径为2mm的圆形凸起S1，卷绕转弯处的凸起S1呈矩阵分布，整个极片上的所有凸起S1呈间歇矩阵分布。其凸起S1的分布密度为12个/cm2，凸起S1高度为80um，然后进行模切、分条，得到厚度为115um的待卷绕正极极片1。Preparation of positive electrode sheet 1 : positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried. Cold pressing, using a special roller to press a circular protrusion S1 with a diameter of 2 mm at the winding turn of the positive electrode tab 1, the protrusion S1 at the winding turn is distributed in a matrix, and all the protrusions S1 on the entire pole piece are in a batch matrix. distributed. The protrusion S1 has a distribution density of 12/cm 2 and the protrusion S1 has a height of 80 μm, and then die-cut and slit to obtain a positive electrode sheet 1 to be wound having a thickness of 115 μm.
负极极片2的制备：将负极活性物质石墨、导电剂乙炔黑、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比96：2：1：1混合均匀并加入到溶剂水中，制成负极浆料；将负极浆料均匀涂布在负极集流体铜箔上，烘干后冷压，压制过程中用特制辊在负极极片2的卷绕转弯处压制直径为2mm的圆形凸起S1，卷绕转弯处的凸起S1呈矩阵分布，整个极片上的所有凸起S1呈间歇矩阵分布。其凸起S1的分布密度为12个/cm2，凸起S1的高度为80um，然后进行模切、分条，得到厚度为115um的待卷绕负极极片2。Preparation of negative electrode sheet 2: the negative electrode active material graphite, conductive agent acetylene black, thickener sodium carboxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) by mass ratio 96:2:1:1 The mixture is uniformly mixed and added to the solvent water to prepare a negative electrode slurry; the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, dried and then cold pressed, and a special roll is used in the winding of the negative electrode piece 2 during the pressing process. The circular protrusion S1 having a diameter of 2 mm is pressed, and the protrusions S1 at the winding turn are distributed in a matrix, and all the protrusions S1 on the entire pole piece are distributed in a matrix. The projection S1 has a distribution density of 12/cm 2 and the height of the projection S1 is 80 μm, and then die-cutting and slitting to obtain a negative electrode tab 2 to be wound having a thickness of 115 μm.
其余的制备步骤同实施例1，这里不在赘述。 The rest of the preparation steps are the same as in the first embodiment, and are not described here.
实施例10Example 10
与实施例9的不同之处：在正极极片1、负极极片2的整个面上均设置了凸起S1。其中，正极极片1、负极极片2上的凸起S1均呈连续矩阵分布，且凸起S1的直径为2mm、分布密度为12个/cm2、的高度为65um。The difference from the embodiment 9 is that the bump S1 is provided on the entire surface of the positive electrode tab 1 and the negative electrode tab 2. The protrusions S1 on the positive electrode tab 1 and the negative electrode tab 2 are all in a continuous matrix distribution, and the protrusion S1 has a diameter of 2 mm, a distribution density of 12/cm 2 , and a height of 65 μm.
实施例11Example 11
与实施例2的不同之处：设置于负极极片2的卷绕转弯处的凸起S1呈长条矩形分布，整个极片上的所有凸起S1呈间歇长条矩形分布。凸起S1的投影贯穿负极极片2的整个宽度且各凸起S1的延伸方向与负极极片2的宽度方向W的夹角ψ为15°，凸起S1的高度为120um，投影矩形的宽度为2mm，间隔为5mm。The difference from the embodiment 2 is that the projections S1 provided at the winding turns of the negative electrode tab 2 are distributed in a long rectangular shape, and all the projections S1 on the entire pole piece are distributed in an intermittent rectangular shape. The projection of the projection S1 penetrates the entire width of the negative electrode tab 2 and the angle θ between the extending direction of each projection S1 and the width direction W of the negative electrode tab 2 is 15°, the height of the projection S1 is 120 μm, and the width of the projection rectangle It is 2mm and the interval is 5mm.
实施例12Example 12
与实施例11的不同之处：设置于负极极片2整个面上的凸起S1呈长条弧形分布，整个极片上的所有凸起S1呈连续长条弧形分布。凸起S1的投影贯穿负极极片2的整个宽度且各凸起S1的延伸方向与负极极片2的宽度方向W的夹角ψ为20°，凸起S1的高度为120um，投影矩形的宽度为2mm，间隔为12mm。The difference from the embodiment 11 is that the protrusions S1 disposed on the entire surface of the negative electrode tab 2 are distributed in a long arc shape, and all the protrusions S1 on the entire pole piece are continuously arcuately distributed. The projection of the projection S1 penetrates the entire width of the negative electrode tab 2 and the angle θ between the extending direction of each projection S1 and the width direction W of the negative electrode tab 2 is 20°, the height of the projection S1 is 120 μm, and the width of the projection rectangle It is 2mm and the interval is 12mm.
实施例13Example 13
与实施例11的不同之处：在正极极片1、负极极片2的卷绕转弯处同时设置凸起S1，整个极片上的所有凸起S1呈间歇呈长条距形分布，凸起S1的投影贯穿极片的整个宽度且ψ为30°，凸起S1的高度为65um，投影矩形的宽度为4mm，间隔为10mm。The difference from the embodiment 11 is that the protrusion S1 is simultaneously disposed at the winding turn of the positive pole piece 1 and the negative pole piece 2, and all the protrusions S1 on the entire pole piece are intermittently distributed in a long strip shape, and the protrusion S1 The projection penetrates the entire width of the pole piece and has a mean of 30°, the height of the protrusion S1 is 65 μm, the width of the projected rectangle is 4 mm, and the interval is 10 mm.
实施例14Example 14
与实施例12的不同之处：在正极极片1、负极极片2的整个面上同时设置凸起S1，整个极片上的所有凸起S1呈连续长条弧形分布，凸起S1的投影贯穿极片的整个宽度且ψ为0°，凸起S1的高度为120um，投影矩形的宽度为8mm，间隔为8mm。 The difference from the embodiment 12 is that the protrusions S1 are simultaneously disposed on the entire surface of the positive electrode tab 1 and the negative electrode tab 2, and all the protrusions S1 on the entire pole piece are continuously arcuately distributed, and the projection of the protrusion S1 is projected. Throughout the entire width of the pole piece and the ψ is 0°, the height of the protrusion S1 is 120 um, the width of the projection rectangle is 8 mm, and the interval is 8 mm.
对比例1Comparative example 1
正极极片1的制备：将正极活性物质Li(Ni1/3Co1/3Mn1/3)O2、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF)按质量比97：2：1混合均匀并加入到作为溶剂的N-甲基-2-吡咯烷酮(NMP)中，制成具有一定粘度的正极浆料；将正极浆料均匀涂布在正极集流体铝箔上，烘干后冷压、模切、分条，做成厚度为115um的锂离子电池正极极片1。Preparation of positive electrode sheet 1 : positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2 :1 is uniformly mixed and added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode slurry having a certain viscosity; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and dried. Cold pressing, die cutting, and slitting were performed to form a positive electrode tab 1 of a lithium ion battery having a thickness of 115 um.
负极极片2的制备：将负极活性物质石墨、导电剂乙炔黑、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按重量比96：2：1：1混合均匀并加入到溶剂水中制成负极浆料；将负极浆料均匀涂布在负极集流体铜箔上，烘干后进行冷压、模切、分条，直接制成厚度为115um的锂离子电池负极片。Preparation of the negative electrode tab 2: the negative electrode active material graphite, the conductive agent acetylene black, the thickener sodium carboxymethyl cellulose (CMC), the binder styrene butadiene rubber (SBR) by weight ratio 96:2:1:1 The mixture is uniformly mixed and added to the solvent water to prepare a negative electrode slurry; the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, dried, and then subjected to cold pressing, die cutting, and slitting to directly form a lithium ion having a thickness of 115 um. Battery negative plate.
隔离膜的制备：选用聚乙烯微孔薄膜作为多孔隔离膜基材；将三氧化铝粉末、聚乙烯呲咯烷酮、丙酮溶剂按重量比为3：1.5：5.5混合均匀制成浆料，将浆料涂布于基材的一面并烘干并分条，制得隔离膜。Preparation of the separator: a polyethylene microporous film is selected as the porous separator substrate; the alumina powder, the polyvinylpyrrolidone, and the acetone solvent are uniformly mixed in a weight ratio of 3:1.5:5.5 to form a slurry. The slurry is coated on one side of the substrate and dried and slit to obtain a separator.
电解液的制备：将六氟磷酸锂溶解于碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂中(碳酸乙烯酯、碳酸二甲酯及碳酸甲乙酯的体积比为1：2：1)，得到所需电解液。Preparation of electrolyte: Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is 1:2:1) , to get the required electrolyte.
锂离子电池的制备：将上述正极极片1、负极极片2以及隔离膜进行卷绕，得到电芯，然后经过封装、注液、化成、排气等工序，制得锂离子电池。Preparation of a lithium ion battery: The positive electrode sheet 1, the negative electrode sheet 2, and the separator are wound to obtain a battery cell, and then subjected to a process of encapsulation, liquid injection, formation, and exhaust to obtain a lithium ion battery.
性能测试Performance Testing
容量保有率：为了表征本发明的电芯用于锂离子电池中的正极极片1和对比例中的锂离子电池的正极极片1对电芯循环寿命和安全性能的影响，对本发明的电芯和对比例中的锂离子电池的电芯分别进行60℃、2C/3C循环800次，考察其容量保有率。在循环测试试验中，电压范围为2.8V～4.2V，以2C的倍率进行充电，以3C的倍率进行放电，循环容量保有率是第800次循环的3C放电容量相对于第2次3C放电容量的比例。Capacity retention rate: in order to characterize the influence of the battery cell of the present invention on the positive electrode pole piece 1 in a lithium ion battery and the positive electrode pole piece 1 of the lithium ion battery in the comparative example on the cycle life and safety performance of the battery, the electricity of the present invention The cells of the lithium ion battery in the core and the comparative example were subjected to a cycle of 60 ° C and 2 C / 3 C for 800 times, respectively, and the capacity retention rate thereof was examined. In the cycle test, the voltage range is 2.8V to 4.2V, charging at a rate of 2C, discharging at a rate of 3C, and the cycle capacity retention rate is the 3C discharge capacity of the 800th cycle relative to the second 3C discharge capacity. proportion.
浸润速度：本发明的电芯用于锂离子电池中的正极极片1和对比例中的锂离子电池的正极极片1对电解液浸润速度的影响，通过将电芯浸泡在电解 液中5小时后取出，放置在90℃下烘干时间来表征，通过判断电芯的内阻是否大于100MΩ来判断电芯是否烘干(如大于100MΩ则烘干)。Wetting speed: The battery cell of the present invention is used for the influence of the positive electrode tab 1 in a lithium ion battery and the positive electrode tab 1 of a lithium ion battery in a comparative example on the infiltration speed of the electrolyte, by immersing the battery core in electrolysis After the liquid is taken out for 5 hours, it is placed at a drying time of 90 ° C to be characterized. It is judged whether the cell is dried by judging whether the internal resistance of the cell is greater than 100 MΩ (for example, drying is greater than 100 MΩ).
表1 各实施例和对比例的检测结果Table 1 Test results of each example and comparative example
Figure PCTCN2017095511-appb-000001
Figure PCTCN2017095511-appb-000001
Figure PCTCN2017095511-appb-000002
Figure PCTCN2017095511-appb-000002
表1为各实施例和对比例的检测结果，从表1的检测结果数据可看出：Table 1 shows the detection results of the respective examples and comparative examples. From the test result data of Table 1, it can be seen that:
压制有凸起S1凸起的极片，无论是矩阵分布还是条纹分布，其在有效改善电解液浸润性的同时，均可显著改善电芯的循环性能。The pole piece with the convex S1 protrusion is pressed, and whether it is a matrix distribution or a stripe distribution, it can significantly improve the cycle performance of the battery while effectively improving the electrolyte wettability.
结合以上对本发明实施例的详细描述可以看出，相对于现有技术，本发明的电芯用于锂离子电池时具有以下优点：In combination with the above detailed description of the embodiments of the present invention, it can be seen that the battery of the present invention has the following advantages when used in a lithium ion battery as compared with the prior art:
首先，极片上的凸起S1凸起能形成层间间隙，有利于增加电解液在电芯内部的渗透，有利于电芯电解液的浸润，尤其是可以有效改善膨胀力集中的电芯卷绕转弯处极片的电解液浸润性能。从而在充放电过程中保证Li+快速迁移能力，从而改善电芯的循环寿命和存储性能。Firstly, the protrusions S1 on the pole piece can form an interlayer gap, which is beneficial to increase the penetration of the electrolyte inside the battery core, and is beneficial to the infiltration of the core electrolyte, especially the core winding which can effectively improve the concentration of the expansion force. The electrolyte wetting property of the pole piece at the turn. Thereby, the Li+ rapid migration capability is ensured during the charging and discharging process, thereby improving the cycle life and storage performance of the cell.
其次，极片上的凸起S1凸起能形成层间间隙，通过起伏结构在极片与隔离膜之间形成支撑骨架，使得极片与隔离膜之间存在一定缓冲间隙，给循环过程膨胀应力集中的极片创造缓冲空间，可有效释放循环过程中极片的膨 胀应力，从而显著减少因极片膨胀导致的扭曲变形，防止因极片破裂造成的电池短路和引发的安全事故，提高锂离子电池的安全性能和循环寿命。Secondly, the protrusion S1 on the pole piece can form an interlayer gap, and a support skeleton is formed between the pole piece and the isolation film through the undulating structure, so that there is a certain buffer gap between the pole piece and the isolation film, and the expansion stress concentration is given to the circulation process. The pole piece creates a buffer space that effectively releases the expansion of the pole piece during the cycle The expansion stress, which significantly reduces the distortion caused by the expansion of the pole piece, prevents the battery short circuit caused by the breakage of the pole piece and the safety accident caused, and improves the safety performance and cycle life of the lithium ion battery.
根据上述原理，本发明还可以对上述实施方式进行适当的变更和修改。因此，本发明并不局限于上面揭示和描述的具体实施方式，对本发明的一些修改和变更也应当落入本发明的权利要求的保护范围内。此外，尽管本说明书中使用了一些特定的术语，但这些术语只是为了方便说明，并不对本发明构成任何限制。 According to the above principle, the present invention can also be appropriately modified and modified as described above. Therefore, the invention is not limited to the specific embodiments disclosed and described herein, and the modifications and variations of the invention are intended to fall within the scope of the appended claims. In addition, although specific terms are used in the specification, these terms are merely for convenience of description and do not limit the invention.

Claims (10)

  1. 一种极片(P)，包括：A pole piece (P) comprising:
    集流体(P1)；以及Current collector (P1);
    活性物质层(P2)，涂覆在集流体(P1)的表面上；An active material layer (P2) coated on the surface of the current collector (P1);
    其特征在于，It is characterized in that
    极片(P)具有多个凸起(S1)，所有凸起(S1)均由集流体(P1)和集流体(P1)表面上的活性物质层(P2)一起沿极片(P)的厚度方向(H)的一侧向外凸出而成，且所有凸起(H)形成于极片(P)的厚度方向(H)的同一侧。The pole piece (P) has a plurality of protrusions (S1), all of which are formed by the current collector (P1) and the active material layer (P2) on the surface of the current collector (P1) along the pole piece (P) One side of the thickness direction (H) is convex outward, and all the protrusions (H) are formed on the same side in the thickness direction (H) of the pole piece (P).
  2. 根据权利要求1所述的极片(P)，其特征在于，The pole piece (P) according to claim 1, characterized in that
    所有凸起(S1)分布于整个极片(P)；或All bumps (S1) are distributed throughout the pole piece (P); or
    所有凸起(S1)形成间隔开的多个凸起集中区(T)。All the protrusions (S1) form a plurality of spaced concentration regions (T) spaced apart.
  3. 根据权利要求2所述的极片(P)，其特征在于，The pole piece (P) according to claim 2, characterized in that
    当所有凸起(S1)分布于整个极片(P)时，所有凸起(S1)在极片(P)表面上的投影面积的总和占极片(P)该表面的总面积的10％-60％；When all the protrusions (S1) are distributed throughout the pole piece (P), the sum of the projected areas of all the protrusions (S1) on the surface of the pole piece (P) accounts for 10% of the total area of the surface of the pole piece (P). -60%;
    当所有凸起(S1)形成间隔开的多个凸起集中区(T)时，各凸起集中区(T)上的所有凸起(S1)在该凸起集中区(T)表面上的投影面积的总和占该凸起集中区(T)所述表面的总面积的10％-60％。When all the protrusions (S1) form a plurality of spaced apart convex concentration regions (T), all the protrusions (S1) on the respective convex concentration regions (T) are on the surface of the convex concentration region (T) The sum of the projected areas accounts for 10% - 60% of the total area of the surface of the raised concentration zone (T).
  4. 根据权利要求2所述的极片(P)，其特征在于，凸起(S1)沿极片(P)的长度方向(L)和宽度方向(W)阵列分布。The pole piece (P) according to claim 2, characterized in that the projections (S1) are distributed along the longitudinal direction (L) and the width direction (W) of the pole piece (P).
  5. 根据权利要求4所述的极片(P)，其特征在于，各凸起(S1)在极片(P)的厚度方向(H)上的投影形状为圆形、椭圆形或多边形。The pole piece (P) according to claim 4, characterized in that the projection shape of each of the projections (S1) in the thickness direction (H) of the pole piece (P) is a circle, an ellipse or a polygon.
  6. 根据权利要求2所述的极片(P)，其特征在于，The pole piece (P) according to claim 2, characterized in that
    各凸起(S1)沿极片(P)的宽度方向(W)延伸而横跨极片(P)的整 个宽度；或各凸起(S1)相对极片(P)的宽度方向(W)倾斜延伸而斜跨极片(P)的整个宽度。Each of the protrusions (S1) extends along the width direction (W) of the pole piece (P) to straddle the pole piece (P) Widths; or each of the protrusions (S1) extends obliquely with respect to the width direction (W) of the pole piece (P) and diagonally across the entire width of the pole piece (P).
  7. 根据权利要求1所述的极片(P)，其特征在于，凸起(S1)在垂直于极片(P)表面的平面上的截面形状为弧形或多线段构成的折线形。The pole piece (P) according to claim 1, characterized in that the cross-sectional shape of the projection (S1) on a plane perpendicular to the surface of the pole piece (P) is a polygonal shape formed by an arc or a plurality of line segments.
  8. 一种电芯，包括：A battery cell comprising:
    正极极片(1)，包括：Positive pole piece (1), including:
    正极集流体(11)；以及Positive current collector (11);
    正极活性物质层(12)，涂覆在正极集流体(11)的表面；a positive active material layer (12) coated on a surface of the positive electrode current collector (11);
    负极极片(2)，包括：The negative pole piece (2) includes:
    负极集流体(21)；以及Anode current collector (21);
    负极活性物质层(22)，涂覆在负极集流体(21)的表面；以及a negative electrode active material layer (22) coated on a surface of the negative electrode current collector (21);
    隔离膜(3)，位于正极极片(1)与负极极片(2)之间；a separator (3) between the positive electrode tab (1) and the negative electrode tab (2);
    其特征在于，正极极片(1)和负极极片(2)中的至少一个采用权利要求1-7中任一项所述的极片(P)。It is characterized in that at least one of the positive electrode tab (1) and the negative electrode tab (2) employs the pole piece (P) according to any one of claims 1-7.
  9. 根据权利要求8所述的电芯，其特征在于，The battery cell according to claim 8, wherein
    仅正极极片(1)采用权利要求1-7中任一项所述的极片(P)；或Only the positive electrode tab (1) uses the pole piece (P) according to any one of claims 1 to 7; or
    仅负极极片(2)采用权利要求1-7中任一项所述的极片(P)；或Only the negative electrode tab (2) uses the pole piece (P) according to any one of claims 1 to 7; or
    正极极片(1)和负极极片(2)均采用权利要求1-7中任一项所述的极片(P)。The positive electrode tab (1) and the negative electrode tab (2) each employ the pole piece (P) according to any one of claims 1-7.
  10. 根据权利要求9所述的电芯，其特征在于，电芯为叠片式电芯或卷绕式电芯。 The battery cell according to claim 9, wherein the battery cell is a laminated battery core or a wound battery core.
PCT/CN2017/095511 2016-08-01 2017-08-01 Pole piece and electrochemical cell WO2018024203A1 (en)

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CN115498136A (en) * 2022-10-24 2022-12-20 江苏正力新能电池技术有限公司 Pole piece, preparation method of pole piece, battery cell and secondary battery
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