WO2023106745A1 - 전극조립체, 이의 제조방법, 및 이를 포함하는 리튬 이차전지 - Google Patents
전극조립체, 이의 제조방법, 및 이를 포함하는 리튬 이차전지 Download PDFInfo
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- WO2023106745A1 WO2023106745A1 PCT/KR2022/019480 KR2022019480W WO2023106745A1 WO 2023106745 A1 WO2023106745 A1 WO 2023106745A1 KR 2022019480 W KR2022019480 W KR 2022019480W WO 2023106745 A1 WO2023106745 A1 WO 2023106745A1
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- Prior art keywords
- electrode
- separator
- electrode assembly
- inclined portion
- positive electrode
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 20
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 20
- 239000011149 active material Substances 0.000 claims abstract description 34
- 230000007423 decrease Effects 0.000 claims abstract description 10
- 238000003475 lamination Methods 0.000 claims description 25
- 239000000853 adhesive Substances 0.000 claims description 24
- 230000001070 adhesive effect Effects 0.000 claims description 24
- 230000000712 assembly Effects 0.000 claims description 12
- 238000000429 assembly Methods 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 9
- 238000010030 laminating Methods 0.000 claims description 7
- 230000003247 decreasing effect Effects 0.000 claims description 2
- 239000008151 electrolyte solution Substances 0.000 claims description 2
- 238000004804 winding Methods 0.000 claims 1
- 230000000052 comparative effect Effects 0.000 description 11
- 239000002002 slurry Substances 0.000 description 10
- 238000001556 precipitation Methods 0.000 description 5
- 239000010408 film Substances 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 239000002612 dispersion medium Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000006183 anode active material Substances 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 235000019640 taste Nutrition 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/043—Processes of manufacture in general involving compressing or compaction
- H01M4/0435—Rolling or calendering
-
- 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
- H01M4/04—Processes of manufacture in general
- H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
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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
- H01M4/139—Processes of manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
- H01M50/105—Pouches or flexible bags
-
- 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
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
- H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/543—Terminals
- H01M50/547—Terminals characterised by the disposition of the terminals on the cells
- H01M50/548—Terminals characterised by the disposition of the terminals on the cells on opposite sides of the cell
-
- 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
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/029—Bipolar electrodes
-
- 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 an electrode assembly, a manufacturing method thereof, and a lithium secondary battery including the same.
- lithium secondary batteries are also required to be miniaturized and thinned, and the demand for them is increasing.
- Such a lithium secondary battery is manufactured by manufacturing a positive electrode and a negative electrode, stacking them together with a separator to form an electrode assembly, and embedding the electrode assembly together with an electrolyte in a secondary battery case.
- the electrode of the secondary battery proceeds by applying the electrode active material slurry to the current collector, and is divided into a holding part to which the slurry is applied and a non-coating part to which the slurry is not applied, and the holding part and the plain surface according to the coating of the electrode active material slurry At both ends, which are the boundary parts of the part, a sliding phenomenon occurs in which the coating is not physically perpendicularly coated but inclinedly coated due to the concentration of the slurry.
- the present invention controls the concentration gradient phenomenon due to the distance during lithium occlusion and release by adhering the portion corresponding to the inclined portion of the active material layer in the same way as the flat portion, thereby solving resistance unevenness and preventing problems such as lithium precipitation.
- An object of the present invention is to provide a secondary battery capable of improving overall performance of the secondary battery and ensuring safety.
- An electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
- the positive electrode and the negative electrode each have a flat portion having a constant thickness of the active material layer and an inclined portion in which the thickness of the active material layer decreases from the flat portion,
- the electrode assembly may be a bicell in which outermost electrodes on both sides have the same polarity, a full cell in which outermost electrodes in the anode have different polarities, and a monocell including one electrode and one or two separators.
- the inclined portion is a first section in which the thickness of the active material layer gradually decreases from a flat portion in a region close to the tab in the extension direction of the tab, or a thickness of the active material layer is flat in the first section and a region far from the tab. It may include a second section that gradually decreases in parts.
- a difference between a distance between the anode and the cathode at the inclined portion and a distance between the anode and the cathode at the flat portion may be 0.4 mm or less.
- the adhesive strength between the positive electrode and the separator at the inclined portion may be 30 gf / 20 mm to 100 gf / 20 mm, and the adhesive strength between the negative electrode and the separator at the inclined portion may be 10 gf / 20 mm to 50 gf / 20 mm. there is.
- the adhesive strength between the positive electrode and the separator at the inclined portion may be 30 gf / 20 mm to 100 gf / 20 mm
- the adhesive strength between the negative electrode and the separator at the inclined portion may be 10 gf / 20 mm to 50 gf / 20 mm.
- the electrode assembly is additionally laminated with a pair of second rollers at positions corresponding to the inclination part of the anode and the inclination part of the cathode, and the inclination part of the anode and the inclination part of the cathode are respectively interposed therebetween.
- a method for manufacturing an electrode assembly comprising the step of adhering to an intervening separator is provided.
- the pair of first rollers may laminate the electrode assembly in consideration of the thickness of the electrode assembly.
- the pair of second rollers have an adhesive strength of 30 gf/20 mm to 100 gf/20 mm between the positive electrode and the separator at the inclined portion at a position corresponding to the inclined portion of the positive electrode and the negative electrode, and the inclined portion
- the electrode assembly may be further laminated so that the adhesive strength between the negative electrode and the separator in is 10 gf / 20 mm to 50 gf / 20 mm.
- the pair of second rollers may include a heating device
- the pair of first rollers may also include a heating device.
- the heating device may apply heat of 40 to 120° C. to the electrode assembly.
- the present invention also provides a lithium secondary battery in which the electrode assembly and the electrolyte solution according to an embodiment of the present invention are embedded in a battery case.
- two or more electrode assemblies may be included, and an additional separator may be included between the two or more electrode assemblies.
- the additional separator may be a unit separator, and the two or more electrode assemblies may be stacked with an additional separator interposed to form a stacked assembly.
- the additional separator may be a separator film, and the two or more electrode assemblies may be wound with the separator film to form a winding-type assembly.
- FIG 1 schematically illustrates an electrode assembly according to an embodiment of the present invention.
- FIG 2 schematically illustrates an electrode assembly according to another embodiment of the present invention.
- FIG. 3 schematically illustrates a part of a method for manufacturing an electrode assembly according to an embodiment of the present invention.
- the present invention is an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
- the positive electrode and the negative electrode each have a flat portion having a constant thickness of the active material layer and an inclined portion in which the thickness of the active material layer decreases from the flat portion,
- An electrode assembly is provided in which the slanted portion of the anode and the slanted portion of the cathode are bonded to a separator interposed therebetween, respectively.
- the electrode assembly is a unit electrode assembly, a bicell in which the outermost electrodes on both sides have the same polarity, and a unit electrode assembly having an anode/separator/cathode/separator/anode or a cathode/separator/anode/separator/cathode structure. It may be a full cell in which the outermost electrodes on both sides have different polarities.
- it may be a unit electrode assembly having an anode/separator/cathode structure, and may be a monocell including one electrode and one or two separators, , It is not limited to this, but in detail, it may be a bi-cell in which the outermost electrodes on both sides have the same polarity.
- the inclined portion is a first section in which the thickness of the active material layer gradually decreases from a flat portion in a region close to the tab in the extension direction of the tab, or a thickness of the active material layer is flat in the first section and a region far from the tab. It may include a second section that gradually decreases in parts.
- the inclined portion may be formed at one end where the tab is formed, and the inclined portion may be formed at both one end and the other end.
- FIG. 1 schematically shows an electrode assembly 100 in which inclined portions are formed at one end and the other end on which tabs are formed according to an embodiment of the present invention.
- the electrode assembly 100 includes two positive electrodes 110, one negative electrode 120, and two separators 130 interposed between the positive electrode 110 and the negative electrode 120.
- two anodes 110 are present on both sides of one cathode 120, respectively.
- the positive electrode 110 and the negative electrode 120 include a flat portion 100a having a constant thickness of the active material layers 112 and 122 formed on the respective current collectors 111 and 121 and a thickness of the active material layer from the flat portion 100a. has a slope (100b) in which is reduced.
- the inclined portion 100b is located in an area close to and far from the tabs 113 and 123 in the extension direction of the tabs 113 and 123 on both sides of the flat portion 100a based on the flat portion 100a.
- the conventional lamination process cannot contact the separator interposed therebetween due to the thickness difference between the anode and the cathode, and accordingly, the separation distance between the anode and the cathode increases, resulting in high resistance at the sloped portion. It takes
- the inclined portions 100b of the positive electrode 110 and the negative electrode 120 of the present application are almost adhered to the separator 130 .
- FIG. 2 schematically shows an electrode assembly 200 in which inclined portions are formed at one end and the other end where tabs are formed according to another embodiment of the present invention.
- the electrode assembly 200 includes one positive electrode 210, two negative electrodes 220, and two separators 230 interposed between the positive electrode 210 and the negative electrode 220.
- two negative electrodes 220 are present on both sides of one positive electrode 210, respectively.
- the positive electrode 210 and the negative electrode 220 include a flat portion 200a having a constant thickness of the active material layers 212 and 222 formed on the respective current collectors 211 and 221 and a thickness of the active material layer from the flat portion 200a. has a slope (200b) in which is reduced.
- the inclined portion 200b is located in an area close to and far from the tabs 213 and 223 in the extension direction of the tabs 213 and 223 on both sides of the flat portion 200a based on the flat portion 200a.
- the inclined portions 200b of the anode 210 and the cathode 220 of the present application are almost adhered to the separator 230.
- the lithium supply rate is similar and the concentration gradient of lithium ions is not large, so the problem of increased resistance or lithium precipitation is similar to that of the flat portion. can solve the problem.
- the difference between the distance between the anode and the cathode at the inclined portion and the distance between the anode and the cathode at the flat portion may be 0.4 mm or less, specifically 0.2 mm, and more Specifically, it may be 50 ⁇ m to 100 ⁇ m.
- the positive electrode and the negative electrode in the inclined portion are bonded to the separator, so that the interval between them is almost similar to the interval between the positive electrode and the negative electrode in the flat portion.
- the adhesive strength between the positive electrode and the separator bonded to the separator at the inclined portion is 30 gf / 20 mm to 100 gf / 20 mm
- the adhesive strength between the negative electrode and the separator bonded to the separator at the inclined portion is 10 gf /20mm to 50gf/20mm.
- the positive electrode and the separator, and the negative electrode and the separator may have adhesive strength of a certain level or higher even at an inclined portion.
- the adhesive strength is measured for the adhesive strength between the positive electrode and the separator when the anode is located in the center of the manufactured electrode assembly, and the adhesive strength between the negative electrode and the separator when the negative electrode is located in the center.
- a force required to separate the electrode assembly from the inclined portion may be measured and obtained by applying a force of 180 degrees at a measurement speed of 10 mm/min.
- the electrode assembly is additionally laminated with a pair of second rollers at positions corresponding to the inclination part of the anode and the inclination part of the cathode, and the inclination part of the anode and the inclination part of the cathode are respectively interposed therebetween.
- a method for manufacturing an electrode assembly comprising the step of adhering to an intervening separator is provided.
- the manufacturing method of the electrode assembly according to the present invention starts with manufacturing an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode.
- the positive electrode and the negative electrode have a flat portion having a constant thickness of the active material layer and an inclined portion having a thickness decreasing from the flat portion by a process of applying the slurry on the current collector through a wet process.
- the manufactured positive electrode and negative electrode are stacked so that the separator is interposed therebetween.
- the materials included in the positive electrode and the negative electrode, the manufacturing method, and the configuration of the separator are well known in the art, and detailed descriptions thereof are omitted herein.
- the electrode assembly may be a unit electrode assembly referred to in the art as a bi-cell or a full cell.
- a step of laminating the electrode assembly with a pair of first rollers is performed.
- the present invention additionally laminates the electrode assembly with a pair of second rollers at a position corresponding to the inclined portion of the positive electrode and the inclined portion of the negative electrode, so that the inclined portion of the positive electrode and the inclined portion of the negative electrode are respectively
- a step of adhering to the separator interposed therebetween is further performed.
- FIG. 2 shows a partial schematic diagram of the electrode assembly manufacturing method of the present invention.
- primary lamination is performed on the electrode assembly 100 ′ with a pair of first rollers 300 .
- the pair of first rollers 300 may laminate the electrode assembly in consideration of the thickness of the electrode assembly.
- lamination is performed with a pair of first rollers 300, and lamination strength may be set in consideration of the overall thickness of the electrode assembly and the distance between the pair of first rollers 300.
- the lamination may be performed at a pressure of 5 MPa to 12 MPa.
- the electrode assembly 100' is formed by using a pair of second rollers 400 so that the inclined portions of the positive and negative electrodes are adhered to the separator at positions corresponding to the inclined portions of the positive and negative electrodes. Additional laminations may be performed.
- the thickness of the active material layer of the positive electrode and the negative electrode portion having the inclined portion is flat. Since it is smaller than the thickness of the active material layer in the portion, sufficient adhesion with the separator interposed therebetween is not achieved.
- the distance between the positive electrode and the negative electrode increases, and a difference occurs in the speed when lithium ions move from the positive electrode to the negative electrode, so lithium precipitation is highly likely to occur, resistance increases, There is a problem that cell performance is degraded.
- the present application may reduce the distance between the anode and the cathode to a level similar to that of the flat part by performing additional lamination once again at a position corresponding to the inclined part.
- the adhesive strength between the positive electrode and the separator at the inclined portion is 30 gf / 20 mm to 100 gf / 20 mm
- the adhesive strength between the negative electrode and the separator at the inclined portion is 10 gf / 20 mm to 10 gf / 20 mm. It can be performed to be 50 gf / 20 mm.
- the additional lamination for this may be performed at a pressure of 0.01 MPa to 8 MPa.
- the positive electrode and the negative electrode in the inclined portion may not adhere to the separator, and the gap may still be wide, and if the pressure is too high, components may be damaged. As it is, it is not desirable.
- the pair of second rollers may include a heating device.
- the pair of first rollers may also include a heating device.
- the heating device may apply heat of 40 to 120° C. to the electrode assembly.
- a lithium secondary battery in which the electrode assembly and the electrolyte are embedded in a battery case.
- the lithium secondary battery may include two or more electrode assemblies, and may have a structure in which an additional separator is included between the two or more electrode assemblies.
- the additional separator is a unit separator, and two or more electrode assemblies may be stacked with an additional separator interposed therebetween to form a stacked assembly, or the additional separator is a separator film, and the two or more electrode assemblies are used for the separation. It may also be wound into a film to constitute a wound assembly.
- the lithium secondary battery according to the present invention may include a stacked or stack-and-folded assembly in which the electrode assembly prepared above is used as a unit electrode assembly.
- a slurry for a positive electrode active material layer was prepared by mixing LiCoO 2 as a positive electrode active material, carbon black as a conductive material, and PVDF as a binder in an N-methylpyrrolidone solvent in a weight ratio of 97.6: 1.1: 1.3, using a slot die.
- the slurry for the positive electrode active material layer was coated on both sides of an aluminum (Al) thin film having a thickness of 10 ⁇ m, which is a positive electrode current collector.
- a mixture of artificial graphite, a binder (SBR and CMC mixed at a weight ratio of 2:1), and carbon black at a weight ratio of 96.4:0.5:3.1 as a conductive material and water as a dispersion medium were used to obtain a weight ratio between the mixture and the dispersion medium.
- a slurry for an anode active material layer mixed in a ratio of 1:2 was prepared. Using a slot die, the slurry for the negative electrode active material layer was coated on both sides of a copper (Cu) thin film having a thickness of 8 ⁇ m, which is an anode current collector.
- Cu copper
- An A-type bi-cell having a cathode/separator/cathode/separator/anode structure was prepared using the above-prepared cathode and anode, and a porous polyethylene separator, and then laminated using a flat press. At this time, lamination was performed under conditions of 100° C. and 9.5 MPa.
- a C-type bicell having a cathode/separator/anode/separator/cathode structure was prepared using the cathode and anode prepared in Comparative Example 1 and the porous polyethylene separator, and then laminated using a flat press. At this time, lamination was performed under conditions of 100° C. and 9.5 MPa.
- the C-type bi-cell with the anode in the center of the bi-cell measures the adhesive strength between the anode and the separator
- the A-type bi-cell with the cathode in the middle measures the adhesive strength between the cathode and the separator
- the anode was separated from the bi-cells prepared in Comparative Examples 1 and 2 and Examples 1 and 2, and pictures were taken and shown in FIGS. 4 and 5 below.
- FIGS. 4 and 5 it can be seen that the separated anode in the comparative examples of FIG. 4 does not adhere to the separator, so that the transfer of the separator is not performed at the upper end.
- FIG. 5 it can be seen that the entirety of the separated anode in the embodiments was transferred.
- an electrode assembly including an anode, a cathode, and a separator
- a portion corresponding to the inclination portion of the active material layer is interposed between them like a flat portion by separately laminating an inclination portion where the thickness of the active material layer decreases.
- the separator By attaching to the separator, the distance between the positive electrode and the negative electrode in the inclined portion is reduced similarly to that of the flat portion, thereby controlling the concentration gradient phenomenon due to the distance during lithium insertion and extraction, and solving the resistance unevenness. Accordingly, the overall performance of a secondary battery including the same can be improved.
- safety can also be secured by preventing problems such as lithium precipitation, which mainly occurred in the inclined portion.
Abstract
Description
접착 강도(gf/20mm) | |
비교예 1 | 접착되어 있지 않음 |
비교예 2 | 접착되어 있지 않음 |
실시예 1 | 20 |
실시예 2 | 40 |
Claims (15)
- 양극, 음극, 및 상기 양극과 음극 사이에 개재되는 분리막을 포함하는 전극조립체로서,상기 양극과 음극은 각각 활물질층의 두께가 일정한 평탄부와 상기 평탄부로부터 상기 활물질층의 두께가 감소하는 경사부를 가지며,상기 양극의 경사부와 상기 음극의 경사부는 각각 이들 사이에 개재되는 분리막과 접착되어 있는 전극조립체.
- 제1항에 있어서,상기 전극조립체는 양측 최외각의 전극이 동일한 극성을 가지는 바이셀, 양극 최외각의 전극이 상이한 극성을 가지는 풀셀, 하나의 전극과 하나 또는 둘의 분리막을 포함하는 모노셀인 전극조립체.
- 제1항에 있어서,상기 경사부는 탭의 연장 방향으로 상기 탭과 가까운 영역에서 활물질층의 두께가 평탄부에서 점진적으로 감소하는 제1 구간, 또는 상기 제1 구간과 상기 탭과 먼 영역에서 활물질층의 두께가 평탄부에서 점진적으로 감소하는 제2 구간을 포함하는 전극조립체.
- 제1항에 있어서,상기 경사부에서의 상기 양극과 상기 음극 사이의 간격과 상기 평탄부에서 상기 양극과 상기 음극 사이의 간격의 차이가 0.4mm 이하인 전극조립체.
- 제1항에 있어서,상기 경사부에서의 상기 양극과 상기 분리막 사이의 접착 강도는 30gf/20mm 내지 100gf/20mm이고, 상기 경사부에서의 상기 음극과 상기 분리막 사이의 접착 강도는 10gf/20mm 내지 50gf/20mm인 전극조립체.
- 제1항에 따른 전극조립체의 제조방법으로서,(a) 상기 양극, 음극, 및 상기 양극과 음극 사이에 개재되는 분리막을 포함하는 전극조립체를 제조하는 단계;(b) 상기 전극조립체를 한 쌍의 제1 롤러들로 라미네이션하는 단계; 및(c) 상기 양극의 경사부와 상기 음극의 경사부에 대응되는 위치에서 상기 적층체를 한 쌍의 제2 롤러들로 추가 라미네이션 하여, 상기 양극의 경사부와 상기 음극의 경사부를 각각 이들 사이에 개재되는 분리막과 접착시키는 단계를 포함하는 전극조립체 제조방법.
- 제6항에 있어서,상기 한 쌍의 제1 롤러들은 상기 적층체의 두께를 고려하여 상기 전극조립체를 라미네이션하는 전극조립체 제조방법.
- 제6항에 있어서,상기 한 쌍의 제2 롤러들은 상기 양극 및 음극의 경사부에 대응하는 위치에서 상기 경사부에서의 상기 양극과 상기 분리막 사이의 접착 강도는 30gf/20mm 내지 100gf/20mm가 되고, 상기 경사부에서의 상기 음극과 상기 분리막 사이의 접착 강도는 10gf/20mm 내지 50gf/20mm가 되도록 상기 전극조립체를 추가 라미네이션 하는 전극조립체 제조방법.
- 제6항에 있어서,상기 한 쌍의 제2 롤러들은 히팅 장치를 포함하는 전극조립체 제조방법.
- 제6항에 있어서,상기 한 쌍의 제1 롤러들은 히팅 장치를 포함하는 전극조립체 제조방법.
- 제9항 또는 제10항에 있어서,상기 히팅 장치는 상기 전극조립체에 40 내지 120℃의 열을 부가하는 전극조립체 제조방법.
- 제1항에 따른 전극조립체, 및 전해액이 전지 케이스에 내장되어 있는 리튬 이차전지.
- 제12항에 있어서,상기 전극조립체는 2 이상 포함되고, 상기 2 이상의 전극조립체들 사이에 추가 분리막이 포함된 리튬 이차전지.
- 제13항에 있어서,상기 추가 분리막은 단위 분리막이며, 상기 2 이상의 전극조립체는 추가 분리막을 사이에두고 적층되어 적층형 조립체를 구성하는 리튬 이차전지.
- 제13항에 있어서,상기 추가 분리막은 분리필름이며, 상기 2 이상의 전극조립체는 상기 분리필름으로 권취되어 권취형 조립체를 구성하는 리튬 이차전지.
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EP22904575.2A EP4270586A1 (en) | 2021-12-06 | 2022-12-02 | Electrode assembly, manufacturing method therefor, and lithium secondary battery comprising same |
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KR20120112669A (ko) * | 2010-03-26 | 2012-10-11 | 미츠비시 쥬고교 가부시키가이샤 | 전지 셀 |
CN105027347A (zh) * | 2013-03-07 | 2015-11-04 | Nec能源元器件株式会社 | 非水电解液二次电池 |
CN105453329A (zh) * | 2013-08-09 | 2016-03-30 | Nec能源元器件株式会社 | 二次电池及其制造方法 |
CN105794022A (zh) * | 2013-12-12 | 2016-07-20 | Nec能源元器件株式会社 | 二次电池及其制造方法 |
KR101802102B1 (ko) * | 2013-10-30 | 2017-11-27 | 닛산 지도우샤 가부시키가이샤 | 전극 및 전극을 갖는 전지 |
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KR20120112669A (ko) * | 2010-03-26 | 2012-10-11 | 미츠비시 쥬고교 가부시키가이샤 | 전지 셀 |
CN105027347A (zh) * | 2013-03-07 | 2015-11-04 | Nec能源元器件株式会社 | 非水电解液二次电池 |
CN105453329A (zh) * | 2013-08-09 | 2016-03-30 | Nec能源元器件株式会社 | 二次电池及其制造方法 |
KR101802102B1 (ko) * | 2013-10-30 | 2017-11-27 | 닛산 지도우샤 가부시키가이샤 | 전극 및 전극을 갖는 전지 |
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