WO2019103467A1 - Electrode assembly having negative electrode disposed as outermost electrode, and lithium-ion secondary battery having same - Google Patents

Electrode assembly having negative electrode disposed as outermost electrode, and lithium-ion secondary battery having same Download PDF

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Publication number
WO2019103467A1
WO2019103467A1 PCT/KR2018/014386 KR2018014386W WO2019103467A1 WO 2019103467 A1 WO2019103467 A1 WO 2019103467A1 KR 2018014386 W KR2018014386 W KR 2018014386W WO 2019103467 A1 WO2019103467 A1 WO 2019103467A1
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WO
WIPO (PCT)
Prior art keywords
electrode
tab
lead
parallel connection
assembly
Prior art date
Application number
PCT/KR2018/014386
Other languages
French (fr)
Korean (ko)
Inventor
김주성
하진홍
이길주
Original Assignee
주식회사 리베스트
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 주식회사 리베스트 filed Critical 주식회사 리베스트
Priority to JP2020546260A priority Critical patent/JP2021503707A/en
Priority to CN201880075524.3A priority patent/CN111386625A/en
Priority to CN202410745961.9A priority patent/CN118554136A/en
Priority to EP18880693.9A priority patent/EP3716390A4/en
Priority claimed from KR1020180144796A external-priority patent/KR102166807B1/en
Publication of WO2019103467A1 publication Critical patent/WO2019103467A1/en
Priority to US16/878,941 priority patent/US11870103B2/en
Priority to JP2023140736A priority patent/JP2023158040A/en
Priority to US18/523,282 priority patent/US20240106091A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • 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 for preventing breakage of electrodes and electrode terminals, which are mechanical problems of a battery, which may occur due to bending and torsion which are repetitive external forces in a flexible environment,
  • a lithium ion secondary battery having an electrode assembly having a structure that minimizes loss of energy density and improves bending durability and safety.
  • a secondary battery is a battery capable of charging and discharging unlike a primary battery which can not be charged, and is widely used in high-tech electronic devices such as a cellular phone, a notebook computer, and a camcorder.
  • high-tech electronic devices such as a cellular phone, a notebook computer, and a camcorder.
  • lithium secondary batteries have higher voltage and higher energy density per unit weight than nickel-cadmium batteries and nickel-hydrogen batteries, which are widely used as power sources for portable electronic equipment, and their demand is increasing.
  • the secondary battery is a battery using an electrochemical reaction generated between an electrolytic material and an electrode when the positive electrode and the negative electrode are connected to each other while an anode and a cathode are inserted into the electrolytic material.
  • a laminated type electrode assembly formed by laminating a plurality of positive electrode plates and negative electrode plates with a separator interposed therebetween in the form of a jelly roll in which a separator is inserted between a positive electrode plate and a negative electrode plate and wound together in a spiral shape is called a lithium secondary It is widely used in batteries.
  • a cylindrical battery includes a cylindrical can accommodated in a cylindrical can, and an electrolyte is injected and sealed.
  • the prismatic type cell is formed by pressing a wound electrode assembly or a stacked electrode assembly to flatten and flatten it, .
  • the pouch-type battery is formed by wrapping a wound electrode assembly or a stacked electrode assembly together with an electrolyte in a pouch-type sheathing material.
  • the positive electrode tab and the negative electrode tab may be respectively drawn out from the positive electrode plate and the negative electrode plate to the outside of the electrode assembly and connected to the positive electrode and the negative electrode of the secondary battery.
  • the electrode tabs are connected to the electrode leads through the plurality of positive electrode plates stacked in the vertical direction and the electrode tabs on the negative electrode plate.
  • the bonding force is somewhat lowered in the process of direct welding, There is a problem in coupling between the electrode tab and the electrode lead through the deformation using operation of the same battery.
  • the terminal portion is easily cut off due to an external impact or force, and the capacity is rapidly decreased to often fail to function as a battery.
  • the metal foil layer is vulnerable to deformation such as wrinkling at the time of bending, thereby deteriorating the characteristics of the flexible battery.
  • Patent Document 1 KR10-2013-0063709 A
  • an object of the present invention to provide an electrode assembly having a plurality of electrodes stacked up and down through a separator, wherein the outermost electrodes are disposed as cathodes to prevent breakage of the electrodes and electrode terminals when the flexible battery is bent , The workability is increased, the energy density loss is minimized, and the bending durability and safety are improved.
  • an electrode assembly comprising: at least one unit cell having a pair of electrode plates having different polarities with a separator interposed therebetween; An electrode material mixture applied on one or both surfaces of the pair of electrode plates; And an electrode tab positioned at an edge of the electrode plate and not yet coated with the electrode mixture, wherein the electrode tab includes an electrode parallel connection tab and an electrode lead connection tab, At least one of electrode tabs for electrode parallel connection and tabs for electrode lead connection is formed and the outermost electrode plate of the electrode assembly has a cathode arranged and stacked.
  • the outermost electrode plate includes both the electrode parallel connection tab and the electrode lead connection tab.
  • a pair of electrode plates having different polarities in a state including only the electrode-parallel connection tab is formed such that the area of the negative electrode mixture applied on the negative electrode plate of the pair of electrode plates is set larger than the area of the positive electrode mixture applied on the positive electrode plate For this reason, the edge of the negative electrode mixture is set to deviate outward within 5 mm from the edge of the positive electrode mixture, and the negative electrode capacity per unit area per unit area is 1 to 1.2 times.
  • the positive electrode plate including only the tab for electrode parallel connection and the positive electrode plate including both the electrode parallel connection tab and the lead connection tab face each other with the separator interposed therebetween,
  • the edges of the negative electrode plate including only the tabs for connecting electrodes for parallel connection are set to be larger than the edges of the positive electrode plate including the electrode connecting tabs and the lead connecting tabs,
  • the negative electrode plate including only the tab for electrode parallel connection covers the tab-lead coupling portion formed on the positive electrode plate.
  • the electrode assembly may be applied to the outermost negative electrode plate disposed at the uppermost and lowermost ends of the electrodes of the electrode assembly.
  • the electrode assembly further includes a reinforcing tab welded and fixed on one of the electrode tabs of the electrode tabs constituting the electrode assembly.
  • the electrode leads connected to the electrode lead connecting tabs of the electrode tabs constituting the electrode assembly are bent in the direction opposite to that of the electrode assembly in the direction opposite to the electrode assembly to be bent toward the outward direction of the electrode assembly, Structure.
  • the tab lead connecting portions of the electrode lead connecting tabs and the electrode leads are padded by using the reinforcing tabs are arranged and arranged inside the separating film.
  • the tab-and-lid coupling portion in which the electrode lead connecting tab and the electrode lead of the bending structure are coupled, is inserted and aligned inwardly of the separating membrane.
  • a lithium ion secondary battery comprising: an electrode assembly; And an outer casing surrounding the electrode assembly.
  • the outer casing is a structure in which the upper and lower depressions are repeatedly pressed to surround the outer surface of the electrode assembly.
  • the plurality of upper crimping portions and the lower crimping portion are continuously formed in a direction parallel to the widths of the electrode assembly and the covering member.
  • At least one electrode constitutes an electrode assembly including a tab for electrode parallel connection and a tab for electrode lead connection, To prevent breakage of the electrode and the electrode terminal, which are mechanical problems of the battery, which may occur due to external bending and torsion in the external environment in a flexible environment.
  • the uppermost and lowermost outermost electrodes serve as cathodes to increase workability, minimize energy density loss, and improve bend durability and safety.
  • FIG. 1 shows an exemplary structure of an electrode assembly constituting a flexible battery according to the present invention.
  • FIG. 2 is an exploded view of an electrode assembly in which an outermost electrode of an electrode assembly is disposed as a cathode according to an embodiment of the present invention.
  • FIGS. 3 and 4 show the arrangement structure of a plurality of electrodes constituting the electrode assembly and a separation membrane disposed between the plurality of electrodes.
  • 5A to 5F show exploded views of various electrode assemblies in a state where the outermost electrodes of the electrode assembly are arranged as an anode and as a cathode.
  • FIG. 6 shows a state in which lithium metal is precipitated on the cathode during charging and discharging by the area of the mixture of the cathode and the anode in the state where the outermost electrode of the electrode assembly is disposed as an anode.
  • FIG. 7 shows areas of a negative electrode mixture and a positive electrode mixture applied on a pair of electrode plates having different polarities in a state including only a tab for electrode parallel connection according to the present invention.
  • FIG. 8 shows the areas of the negative electrode mixture and the positive electrode mixture on the positive electrode plate including both the negative electrode plate including only the tab for electrode parallel connection and the tab for connecting in parallel with the electrode and the lead connecting tab.
  • Fig. 9 shows a flexible battery having an electrode assembly and a covering member surrounding the electrode assembly.
  • FIG. 10 shows a state in which a pattern such as an upper pressing portion and a lower pressing portion is formed in a direction parallel to the width of the exterior material portion in the exterior material portion constituting the flexible battery.
  • FIG. 11 illustrates a specific shape of the upper and lower pressing portions formed on the casing member.
  • FIG. 12 is a graph showing a bending cycle according to charging and discharging when the outermost electrode of the electrode assembly is arranged as a cathode, the outermost electrode is arranged as an anode, and a general battery is combined according to an embodiment of the present invention .
  • FIGS 13A to 13C are views for explaining an embodiment according to the electrode width and the width of the tab for lead connection according to the present invention.
  • FIG. 14 is a view for explaining a method for improving the flexibility of a battery by stacking electrodes according to an embodiment of the present invention.
  • FIG. 15 is a sectional view of an electrode assembly according to an embodiment of the present invention.
  • the electrode assemblies are assembled by forming the outermost electrodes of the electrode assembly into an anode and a cathode, And a bending evaluation result of a battery composed of the electrode assemblies produced.
  • the electrode assembly includes an anode plate 10 and an anode plate 20, an electrolyte solution serving as an ion transfer medium between the anode plate and the anode plate, an electrode tab located at the edge of the electrode plate, .
  • Any one or more of the electrode plates including the negative electrode plate 10 and the positive electrode plate 20 may be disposed on both sides of the tab for electrode parallel connection and the tab for electrode lead connection.
  • an optional cathode plate 10 disposed at the uppermost or lowermost end of the electrode assembly 100 has a cathode-parallel connection tab 12 and a cathode lead connection tab 14, and the optional cathode plate 10
  • the optional positive electrode plate 20 disposed at the boundary of the separator has the positive electrode parallel connection tab 22 and the positive electrode lead connection tab 24.
  • the electrode plates are in the form of an electrode mixture applied on one or both surfaces of the electrode current collector, and the tabs for electrode parallel connection and the tabs for electrode lead connection are formed in such a manner that the electrode current collector is exposed to be.
  • the plurality of electrode plates are connected to each other through the electrode tabs for electrode parallel connection. That is, the plurality of negative electrode plates 10 and the plurality of positive electrode plates 20 are electrically connected in parallel by the tab-to-tab joints connecting the electrode tabs.
  • the separator can be positioned between the electrode plates having different polarities and functions to block the flow of electrons but to pass ions contained in the electrolyte.
  • the tabs 12 and 22 for parallel connection of the electrodes formed on the edge of the anode plate 10 or the anode plate 20 allow the electrode plates of the same polarity to be electrically connected in parallel with each other.
  • the tab-to-tab joints connected in parallel are positioned on the separation membrane that surrounds the outer surface of the outermost electrode plate forming the uppermost or lowermost end of the electrode assembly, and subjected to finish taping.
  • the separator may be a zigzag laminate in which the cathode plate 10 and the anode plate 20 are continuously stacked with the separator 30 interposed therebetween.
  • the conventional method of simply laminating the negative electrode plate and the positive electrode plate causes safety problems due to lithium precipitation and internal short circuit due to deviation and misalignment of electrodes and separators in the electrode assembly due to external bending and twisting.
  • the tab-to-tab joint electrically connecting the zigzag lamination method and the parallel connection tabs catches the electrodes in the electrode assembly, it is possible to minimize separation and misalignment even in a flexible environment.
  • a separate reinforcing tab 70 can be reinforced on the electrode lead connecting tabs 14 and 24 disposed on one side of the electrode assembly.
  • the electrode lead connecting tabs 14 and 24 and the electrode lead 60 are connected to the tab-and-lid connecting portion 50 of the overtight structure by using the reinforcing tabs 70 by coupling the electrode leads 60 to the reinforcing tabs 70 ).
  • the reinforcing bonding method for bonding the electrode lead connecting tabs 14 and 24 to the electrode lead 60 using the reinforcing tab 70 corresponds to at least one of the positive electrode tab and the negative electrode tab.
  • the reinforcing tab 70 is physically reinforced by reinforcing the strength of the connection portion between the electrode lead connecting tabs 14 and 24 and the electrode lead 60.
  • the same or different metal reinforcing tabs 70 which are 1 to 5 times thicker than the electrode lead connecting tabs, are welded to the upper ends of the tabs for electrode lead connection extending from the electrode plates of the electrode assembly.
  • the reinforcing tabs 70 reinforced by the overhangs and the tabs for connecting the electrode leads have the same or different widths.
  • the reinforcing tab 70 may have a width of 3 mm to 5 mm and a length of 2 mm to 4 mm, but this is not limitative.
  • the electrode leads which are joined to the electrode lead connecting tabs by bonding on the reinforcing tabs 70 reinforced by the overhang, may have a width of 2 mm to 3 mm and a length of 0.5 mm to 1 mm, But is not limited thereto.
  • the current collector of the electrode plate may be any one of a group including aluminum, stainless steel, and copper, and the electrode lead may have any one material selected from the group consisting of aluminum, nickel, and nickel coated with nickel have.
  • the tabs for electrode lead connection and the reinforcing tabs to be reinforced by the overhang on the tab-lead connection portion of the electrode lead are formed in one of the group including circle, ellipse and polygon.
  • the electrode leads connected to the electrode lead connecting tabs of the electrode tabs constituting the electrode assembly are bent in the direction opposite to the direction of 180 ° in the state of being joined to the electrode assembly,
  • the bending tab 80 structure can be formed. This is characterized by a joint reinforcing structure between the electrode tabs and the electrode leads by minimizing the local mechanical load in a flexible environment.
  • the electrode lead connecting tabs and the electrode leads 60 may be bonded to each other by bending.
  • the width of the electrode leads 60 connected to the electrode lead connecting tabs may be at least one of 2 mm to 3 mm, and a length of 1 mm to 3 mm, but this is not limitative.
  • a tab-and-lid connection portion 50 is formed by combining the electrode lead connecting tabs 14 and 24 and the electrode lead 60 by using the reinforcing tabs 70 and the electrode lead connecting tabs and bend tabs 80
  • the tab-and-lid engagement portion 50 to which the electrode lead 60 is joined has a state in which it is inserted / aligned inwardly of the separator, that is, inwardly disposed. This protects the flexible battery by preventing external exposure of the terminal part, which is the weakest point of the flexible battery.
  • the electrodes B and B 'provided with the electrode lead connecting tab and the parallel connecting tab are smaller in area than the electrode C having only the electrode connecting tab.
  • the mixed layer area of the electrode (B) disposed on the outer side of the electrodes (B, B ') is larger than the mixed layer area of the electrode (B') disposed on the inner side.
  • the electrode (B) corresponds to the outermost electrode which is the cathode
  • the electrode (B ') is the anode electrode plate which faces the outermost electrode and the separator. That is, an electrode B as a cathode is disposed on the lowest layer on the electrode assembly, and an electrode B 'as an anode is disposed immediately above the electrode B.
  • an electrode (C) having only a tab for electrode parallel connection which is a cathode is disposed.
  • general electrodes in a state in which only a parallel connection tab is formed may be additionally disposed between the electrode (B ') and the electrode (C).
  • 5A to 5F show exploded views of various electrode assemblies in a state where the outermost electrodes of the electrode assembly are arranged as an anode and as a cathode.
  • FIG. 6 shows a state in which lithium metal is precipitated on the cathode during charging and discharging by the area of the mixture of the cathode and the anode in the state where the outermost electrode of the electrode assembly is disposed as an anode.
  • the electrode tab / lead coupling portion is positioned inside the electrode without being exposed to the outside of the electrode.
  • the most effective way to accomplish this is to reduce the area of the mixed layer applied to the electrode having the electrode-parallel connection tab and the electrode lead connection tab at the same time as compared with the electrode having only the electrode-parallel connection tab.
  • the area of the mixed layer of the anode facing the cathode having the electrode lead connecting tab should be reduced accordingly.
  • the reason for this is that if not, the lithium extracted from the anode at the time of charging precipitates in the vicinity of the edge of the cathode to decrease the capacity and efficiency and increase the resistance, and the precipitated lithium grows into a needle- (Internal short) occurs.
  • the outermost electrode of the electrode assembly is a cathode
  • the outermost anode should be coated in a cross section, and in the case of the anode located in the middle layer, the cathode mixture coating layer containing the cathode active material includes the anode active material It is necessary to provide an uncombusted area so as to face the negative electrode mixture layer at the entire area.
  • the outermost anode has to be coated in a cross-section, and a cathode having both a tab for electrode-parallel connection and a tab for electrode lead connection and a tab for electrode-
  • a cathode having both a tab for electrode-parallel connection and a tab for electrode lead connection and a tab for electrode-
  • the thickness step is increased in the vicinity of the negative electrode lead / tab joint portion on the basis of the thickness direction of the electrode assembly in which the electrodes are stacked, thereby lowering the bending quality of the flexible battery due to breakage of the joint portion.
  • an adhesive tape composed of an inactive material that does not react with the electrolyte solution and an acrylic or urethane-based adhesive that blocks the flow of ions is attached to the portion 502 where the negative electrode and the positive electrode are not confronted with each other,
  • a flexible member 502 such as a flexible printed circuit board or the like must be added.
  • Electrodes be manufactured in various sizes and types, such as electrodes with only tabs for parallel connection to the positive and negative electrodes, and electrodes with leads to the lead connection tabs, Design, and management, and the use of additional materials requires very low fairness, resulting in higher manufacturing costs and lower energy density.
  • electrodes of various sizes and types such as electrodes having only a tab for parallel connection to the anode and the cathode, and electrodes having both of the electrodes for connection to the lead electrode, and it is necessary to design and manage both the anode- So that the fairness is very low and the manufacturing cost is increased.
  • the thicknesses of the internal electrodes make the durability more vulnerable to battery usage such as bending and twisting. Therefore, unless the step difference generating portion 505 is supplemented by a method of filling the step difference generating portion 505 with a flexible inert material or the like, cracks and cuts may occur at portions where the mechanical rigidity and ductility are weak, This causes an impossible problem.
  • the electrode having the lead connecting tab and the electrode lead are biased to the outermost one of the electrodes of the electrode assembly when the above-mentioned problems are considered.
  • FIGS. 7 and 8 a method of designing an area of an electrode mixture layer suitable for solving the above-mentioned problem is shown.
  • the energy density becomes lower accordingly, which is not preferable.
  • the area to be coated must be different from that of the positive electrode, It can be said that it is preferable to constitute a cathode.
  • FIG. 7 shows that the area of the negative electrode mixture applied on the negative electrode plate among the pair of electrode plates having different polarities in the state including only the electrode parallel connection tab is set larger than the area of the positive electrode mixture applied on the positive electrode plate.
  • the difference (d) between the edges of the anode mixture and the edge of the anode mixture is designed to deviate outward within a range of 5 mm.
  • the anode capacity per unit area with respect to the anode capacity per unit area is 1 to 1.2 times.
  • FIG. 8 is a cross-sectional view of a positive electrode plate including only a tab for electrode parallel connection and a positive electrode plate including both a tab for electrode parallel connection and a tab for lead connection,
  • the area of the negative electrode mixture is set larger than the area of the positive electrode plate including both the electrode-parallel connection tab and the lead connection tab.
  • the difference (d) between the edges of the anode mixture and the edge of the anode mixture is designed to deviate outward within a range of 5 mm. Furthermore, by disposing the connection portion between the electrode tab and the electrode terminal, that is, the tab-lead coupling portion 50 formed on the positive electrode plate, in the separator of the electrode assembly, it is possible to prevent cracking or cutting in the weak portion .
  • the negative electrode plate including only the tab for electrode parallel connection can be designed to be large by the length (D) of the electrode tab formed on the edge of the positive electrode plate including the tab-lead coupling portion 50 and uncoated with the positive electrode mixture.
  • the negative electrode plate including only the tab for electrode parallel connection be covered with the positive electrode plate including both the electrode connection tab and the lead connection tab.
  • the electrode assembly according to the present invention disposes the outer casing part 200 of the processed structure of the upper and lower pressing parts of the electrode assembly so as to surround the outer periphery of the electrode assembly.
  • the pattern and shape are repeated so as to enable compression and tensioning of a flexible battery having an electrode assembly in a bending, twisting or wrinkling operation, in which a plurality of upper depressing portions and lower depressing portions repeatedly stamped on the casing member are repeated .
  • the plurality of upper depressions and lower depressions may be formed continuously in a direction parallel to the widths of the electrode assembly and the casing.
  • the plurality of upper depressions and lower depressions may be depressed into upper and lower dies, respectively.
  • the outer covering member surrounding the outer surface of the electrode assembly may have an upper casing member 210 and a lower casing member 220 on the electrode assembly with reference to a red dotted line of the sealing member 230. That is, the plurality of upper depression portions 212 and 222 and the lower depression portions 214 and 224 repeated on the casing member are formed symmetrically with respect to the ceiling portion, and the upper and lower casing members 210 and 210 220). ≪ / RTI > In this state, the electrode assembly is housed in the exterior member after the sealing portion is bent symmetrically upward and downward.
  • the width of the sealing portion which is a reference for separating the upper and lower casing members 210 and 220, may be 3 mm to 5 mm and the actual sealing width may be 1 mm to 2 mm, But is not limited thereto.
  • the present invention is not limited thereto.
  • the present invention is characterized in that a cathode is disposed on an outermost electrode of an electrode assembly having a plurality of electrodes stacked vertically through a separation membrane to prevent breakage of the electrode terminal when the flexible battery is bent.
  • FIG. 12 is a graph showing the relationship between the outermost electrode as a cathode, the outermost electrode as an anode, the electrode parallel connection taps and the electrode lead connecting taps as separate cells according to an embodiment of the present invention.
  • FIG. 3 is a graph showing changes in battery voltage according to the number of bending operations performed simultaneously with charging / discharging. The test conditions were charging and discharging in real time while repeating bending with a curvature radius of 25 mm and a bending rate of 20 cycles per minute and monitoring the voltage
  • the results of bending evaluation of the negative electrode and the positive electrode are shown on the outermost electrode.
  • the electrode lead-tab joint portion was broken without exceeding 30 times of bending.
  • the outermost electrode was arranged as an anode, voltage noise occurred around 3,800 times, and then a sudden voltage drop occurred during charging.
  • the outermost electrode was applied to the cathode, there was no damage to the terminal portion of the electrode and the electrode even when bending was performed over 6,000 times, and normal electrochemical actuation was shown.
  • the electrode assembly according to the present invention includes an anode and a cathode having different polarities in sequence, including a separator, in which the outermost electrode at the uppermost stage and the outermost electrode at the lowermost stage are used as cathodes to improve the processability, minimize the energy density loss, Bending durability and safety.
  • FIGS 13A to 13C are views for explaining an embodiment according to the electrode width and the width of the tab for lead connection according to the present invention.
  • the electrode width of the first electrode (Electrode 1) and the width of the lead connection tab are Wn1 and Wn2, the electrode width of the second electrode (Electrode 2) and the width of the lead connection tab are Wp1 , Wp2.
  • 13A is a diagram for explaining a case where Wn2 is at least half of Wn1 and Wp2 is at least half of Wp1.
  • the widths Wn2 and Wp2 of the lead connecting taps of the neighboring electrodes are equal to or more than half of the electrode widths Wn1 and Wp1 And may be formed so that predetermined regions overlap each other between the electrodes.
  • the present invention compensates the phenomenon by disposing the tab-lead coupling portion, in which the electrode tab and the electrode lead are coupled, into the separation membrane of the electrode assembly.
  • the electrode tab is damaged and broken even in the membrane. This was due to deformation of the material formed along the step at the time of bending due to the step difference in thickness between the electrode tabs and the tab-to-lead joints disposed inside the separator and the electrodes stacked at different sizes.
  • the present invention proposes a flexible battery manufacturing method as described below in order to solve the above problems by minimizing the thickness step in the electrode assembly.
  • the electrode tabs having different polarities, and the electrode tabs of the respective electrodes connected to the (+) electrode lead and the (-) electrode lead are disposed outside the separation membrane so as to be positioned on the same line in the same direction,
  • internal short-circuiting may occur, which may cause a safety problem. That is, in order not to cause such a problem, the electrode taps of the respective electrodes having different polarities are separated in the opposite directions or spaced apart from each other so as not to overlap each other. According to the positional relationship between the electrode taps of the respective electrodes, The width of the electrode tab is formed.
  • each electrode of the present invention can improve the degree of design freedom with respect to the width of the electrode tab formed in each electrode. For example, assuming that the electrode widths of the electrodes of different polarities are Wn1 and Wp1, respectively, as shown in Fig. 13A, the widths Wn2 and Wp2 of the lead connecting tabs are equal to or larger than half of the electrode widths Wn1 and Wp1 .
  • the widths Wn2 and Wp2 of the lead connecting tabs of the respective electrodes are formed to be equal to or more than half of the electrode widths Wn1 and Wp1 of the respective electrodes, It is possible to prevent cracking and disconnection.
  • the width 1301 of the lead connecting tab of the first electrode and the width 1302 of the lead connecting tab of the second electrode may be the same as the electrode width of each electrode.
  • the tab-and-lid coupling portion and the electrode tab can be disposed inside the separation membrane of the electrode assembly, thereby preventing a short-circuit between the electrodes.
  • FIG. 13C is a view for explaining a method of reducing a thickness step due to uncoated coating in an electrode tab-and-lead joint according to an embodiment of the present invention.
  • a flexible material which does not react with the positive electrode (For example, a resin such as acrylic or urethane, and a film, a tape, or a pressure-sensitive adhesive that is made by mixing these materials can be inserted or adhered).
  • the flexible material described above has flexibility similar to or better than that of each of the electrode mixture layers constituting the electrode assembly Good things can be adopted.
  • FIG. 14 is a view for explaining a method for improving the flexibility of a battery by stacking a plurality of electrodes according to an embodiment of the present invention.
  • flexibility of a battery can be improved by manufacturing a flexible battery having various electrode stacking structures and stacked numbers by using the present invention.
  • the tab-lead coupling portion formed by connecting the electrode lead and the electrode tab is located in the separation membrane of the electrode assembly.
  • the present invention effectively reduces the thickness step formed in the region of the electrode tab-and-lead connection portion of each electrode, thereby enabling more flexible flexibility and stable driving in a use environment requiring bending characteristics of the battery, You can be safe from the same risks.
  • the width of the tab for connecting the electrode leads to be connected to the electrode leads can be designed to be larger than that of the conventional flexible battery, thereby ensuring a stable current flow path, And safety can be ensured by minimizing the heat generated by the resistance.
  • FIG. 15 is a sectional view of an electrode assembly according to an embodiment of the present invention.
  • the electrode assemblies are manufactured by dividing the outermost electrode into an anode and a cathode
  • FIG. 3 is a graph showing a result of bending evaluation of a battery composed of one electrode assembly.
  • the evaluation samples were classified into four types (the outermost electrodes were arranged as cathodes + the conventional electrode tabs and the outermost electrodes were arranged as cathodes + the developed electrode tabs, the outermost electrodes were arranged as anodes + the conventional electrode tabs, + Development electrode tab).
  • the electrode lead connecting tabs which are located inside the separating film of the electrode assembly and are formed between electrodes of different polarities facing each other with the separating film facing each other, as described above, Quot; means an electrode tab configured to overlap with each other on the basis of a region.
  • the voltage was monitored while repeated bending evaluation was performed using each sample having a 50% charged state.
  • the test conditions are the result of checking the voltage in real time while repeating bending with a curvature radius of 20 mm and a bending rate of 25 times per minute.
  • the cell with the outermost electrode of the electrode assembly has a better durability than the cell with the outermost electrode as the anode, and the battery composed of the developed electrode tab has better durability than the existing electrode tab. Therefore, according to the present invention, a flexible battery having a negative electrode and an outermost electrode of an electrode assembly and having a developed electrode tab structure is considered to be superior in durability due to external force such as repetitive bending, compared with a conventional flexible battery.

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Abstract

An electrode assembly, according to the present invention, comprises: at least one unit cell having a pair of electrode plates having different polarities from each other and having a separator interposed therebetween; an electrode mixture applied on one surface or both surfaces of the pair of electrode plates; and an electrode tab positioned on the respective edges of the electrode plates while at the same time, being in a state where the electrode mixture is not applied thereon. The electrode tab includes an electrode parallel connecting tab and an electrode lead connecting tab. The electrode plates have formed thereon at least one electrode tab among the electrode parallel connecting tab and the electrode lead connecting tab. The outermost electrode plate is in a negative electrode state.

Description

최외곽 전극이 음극으로 배치된 전극 조립체 및 상기 전극 조립체를 갖는 리튬이온 이차전지An electrode assembly in which an outermost electrode is disposed as a cathode, and a lithium ion secondary battery
본 발명은 플렉서블한 환경에서 외부의 반복적인 힘인 굽힘과 비틀림 등에 의해 발생할 수 있는 전지의 기계적 문제인 전극 및 전극 단자의 파손을 방지하고, 전극조립체의 최외곽 전극을 음극으로 배치하여 작업성을 높임과 동시에 에너지밀도 손실을 최소화하고, 굽힘 내구성 및 안전성을 향상시키는 구조의 전극 조립체를 갖는 리튬이온 이차전지에 대한 것이다.The present invention relates to an electrode assembly for preventing breakage of electrodes and electrode terminals, which are mechanical problems of a battery, which may occur due to bending and torsion which are repetitive external forces in a flexible environment, A lithium ion secondary battery having an electrode assembly having a structure that minimizes loss of energy density and improves bending durability and safety.
이차 전지(secondary battery)는 충전이 불가능한 일차 전지와는 달리 충전 및 방전이 가능한 전지를 말하는 것으로서, 셀룰라 폰, 노트북 컴퓨터, 캠코더 등의 첨단 전자 기기 분야에서 널리 사용되고 있다. 상기 휴대형 전자기기의 경량화와 고기능화 및 사물인터넷(Internet of things, IoT)이 발전함에 따라 그 구동 전원으로 사용되는 이차전지에 관한 많은 연구가 이루어지고 있다.A secondary battery is a battery capable of charging and discharging unlike a primary battery which can not be charged, and is widely used in high-tech electronic devices such as a cellular phone, a notebook computer, and a camcorder. [0003] As the portable electronic devices have become lighter and more sophisticated and the Internet of things (IOT) has developed, much research has been conducted on secondary batteries used as driving power sources.
특히, 리튬 이차 전지는 휴대용 전자 장비 전원으로 많이 사용되고 있는 니켈-카드뮴 전지나, 니켈-수소 전지보다 전압이 높고, 단위 중량당 에너지 밀도도 높다는 장점이 있어서 그 수요가 증가하고 있는 추세이다.Particularly, lithium secondary batteries have higher voltage and higher energy density per unit weight than nickel-cadmium batteries and nickel-hydrogen batteries, which are widely used as power sources for portable electronic equipment, and their demand is increasing.
이차 전지는 전해물질에 양극과 음극을 삽입한 상태에서, 상기한 양극과 음극을 연결했을 때 전해물질과 전극 사이에서 발생되는 전기화학적 반응을 이용한 전지로서, 기존의 일차전지와는 달리 전기전자제품에서 소모된 에너지를 충전기에 의해 재충전하여 반복 사용할 수 있는 충전과 방전이 가능한 전지이므로 무선 전기전자제품의 대중화와 더불어 확산되고 있는 추세이다.The secondary battery is a battery using an electrochemical reaction generated between an electrolytic material and an electrode when the positive electrode and the negative electrode are connected to each other while an anode and a cathode are inserted into the electrolytic material. Unlike a conventional primary battery, Is a battery capable of recharging and recharging the energy consumed by the battery charger and used repeatedly, so that it is spreading with the popularization of wireless electric and electronic products.
통상적으로, 양극판과 음극판과의 사이에 분리막을 삽입하고 이들을 함께 나선형으로 권취시킨 젤리롤 형태의 권취형 전극 조립체, 또는 분리막을 사이에 두고 다수의 양극판과 음극판을 적층하여 형성된 적층형 전극 조립체를 리튬 이차 전지에 많이 사용하고 있다. 예를 들어, 원통형 전지는 권취형 전극 조립체를 원통형 캔에 수납하고 전해질을 주입한 후 밀봉하는 것이고, 각형 전지는 권취형 전극 조립체나 적층형 전극 조립체를 압박하여 납작하고 평평하게 만든 다음 각형 캔에 수납하는 것이다. 또한, 파우치형 전지는 권취형 전극 조립체나 적층형 전극 조립체를 전해질과 함께 파우치형 외장재로 포장한 것이다. 이러한 전극 조립체에서, 양극판과 음극판으로부터 각각 양극탭과 음극탭이 전극 조립체의 외부로 인출되어 이차 전지의 양극과 음극에 연결될 수 있다.Typically, a laminated type electrode assembly formed by laminating a plurality of positive electrode plates and negative electrode plates with a separator interposed therebetween in the form of a jelly roll in which a separator is inserted between a positive electrode plate and a negative electrode plate and wound together in a spiral shape is called a lithium secondary It is widely used in batteries. For example, a cylindrical battery includes a cylindrical can accommodated in a cylindrical can, and an electrolyte is injected and sealed. The prismatic type cell is formed by pressing a wound electrode assembly or a stacked electrode assembly to flatten and flatten it, . The pouch-type battery is formed by wrapping a wound electrode assembly or a stacked electrode assembly together with an electrolyte in a pouch-type sheathing material. In such an electrode assembly, the positive electrode tab and the negative electrode tab may be respectively drawn out from the positive electrode plate and the negative electrode plate to the outside of the electrode assembly and connected to the positive electrode and the negative electrode of the secondary battery.
한편, 상하 방향으로 적층된 다수의 양극판과 음극판 상의 전극 탭을 통해 전극 리드에 연결하게 되는데, 종래의 전극 탭과 전극 리드 간의 결합구조는 직접 용착을 하는 과정에서 결합력이 다소 떨어지게 됨으로써, 구부리는 것과 같은 전지의 변형 사용 동작을 통해서 상기 전극 탭과 전극 리드 간에 결합에 문제가 발생하게 된다.Meanwhile, the electrode tabs are connected to the electrode leads through the plurality of positive electrode plates stacked in the vertical direction and the electrode tabs on the negative electrode plate. In the conventional joint structure between the electrode tabs and the electrode leads, the bonding force is somewhat lowered in the process of direct welding, There is a problem in coupling between the electrode tab and the electrode lead through the deformation using operation of the same battery.
전극 조립체 및 상기 전극 조립체를 감싸는 외장재를 갖는 기존의 리튬 이차 전지는 굽힘(벤딩) 평가가 진행되는 경우에, 외장재의 손상과 동시에 전극 조립체 내의 구성요소인 양극, 음극, 전극 리드, 분리막들의 이탈 및 오정렬에 의한 단락 문제가 발생한다. 상기와 같이, 기존의 리튬이온 이차전지의 경우에는 외부의 충격이나 힘에 의해 단자 부분이 쉽게 절단되어 용량이 급격히 감소하면서 전지로서의 기능을 하지 못하는 경우가 많았다.In the conventional lithium secondary battery having the electrode assembly and the casing surrounding the electrode assembly, when the bending evaluation is performed, damage to the casing and detachment of the positive electrode, the negative electrode, the electrode lead, A short circuit problem due to misalignment occurs. As described above, in the case of a conventional lithium ion secondary battery, the terminal portion is easily cut off due to an external impact or force, and the capacity is rapidly decreased to often fail to function as a battery.
한국 공개특허공보 제10-2013-0063709호를 참조하여 파우치형 전지를 예를 들어 설명하면, 두 전극과 분리막, 전해질을 파우치에 넣고 실링하여 사용하는 파우치형 이차전지에 있어서, 파우치가 내부 수지 층, 금속박 층, 외부 수지 층으로 이루어지고, 내부 수지 층과 금속박 층이 맞닿는 면에 금속박 층 보다 반응성이 작은 버퍼 층이 형성되어 있다고 개시되어 있다. 이 경우, 금속박 층 보다 반응성이 작은 버퍼 층을 추가로 형성함으로써, 내부 수지 층에 마이크로 크랙(micro crack)이 발생하는 등 손상이 가는 경우에도 금속박 층의 산화 반응을 막음으로써, 전지의 외측 부식을 방지할 수 있는 장점이 있지만, 근본적으로 금속박은 벤딩시 구겨짐과 같은 변형에 취약하여 플렉서블 전지의 특성을 저하시키는 문제점이 있다.For example, in a pouch-type secondary battery according to Korean Patent Laid-Open Publication No. 10-2013-0063709, a pouch type secondary battery using two electrodes, a separator, and an electrolyte in a pouch and sealing them, , A metal foil layer, and an outer resin layer, and a buffer layer having less reactivity than the metal foil layer is formed on the surface where the inner resin layer and the metal foil layer are in contact with each other. In this case, by further forming a buffer layer having less reactivity than the metal foil layer, the oxidation reaction of the metal foil layer is prevented even when damage occurs such as micro cracks in the internal resin layer, However, the metal foil is vulnerable to deformation such as wrinkling at the time of bending, thereby deteriorating the characteristics of the flexible battery.
종래 기술에서 일반적인 전지 어셈블리의 굽힘 동작시에는 굽힘 안쪽은 압축응력이 인가되고, 그 반대쪽에는 인장응력이 전지에 인가됨에 따라, 전지의 전극 조립체를 감싸는 외장재도 늘어나거나 좁혀지면서 국부적인 기계적 파손이 발생한다. 따라서, 플렉서블 전지의 외장재뿐 아니라 내부의 전극 조립체를 구성하는 전극판 및 전극 탭, 전극 리드 간 구조의 개선으로 새로운 플렉서블 전지 어셈블리가 필요한 상황이다.In the prior art, when a bending operation of a general battery assembly is performed, compressive stress is applied to the inside of the bend, and tensile stress is applied to the opposite side of the bend, so that the external covering material surrounding the electrode assembly of the battery is expanded or narrowed. do. Therefore, a novel flexible battery assembly is required for improving the structure between the electrode plate, the electrode tab, and the electrode lead constituting the inner electrode assembly as well as the outer casing of the flexible battery.
(특허문헌 1) KR10-2013-0063709 A(Patent Document 1) KR10-2013-0063709 A
따라서, 본 발명이 해결하고자 하는 과제는, 분리막을 통해 상하로 적층되는 복수의 전극을 갖는 전극 조립체에서 최외곽 전극을 음극으로 배치함으로써, 플렉서블 전지의 굽힘 시에 전극 및 전극 단자의 파손을 방지하고, 작업성을 높임과 동시에 에너지밀도 손실을 최소화하며, 굽힘 내구성 및 안전성을 향상시키는 것을 목적으로 한다.SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an electrode assembly having a plurality of electrodes stacked up and down through a separator, wherein the outermost electrodes are disposed as cathodes to prevent breakage of the electrodes and electrode terminals when the flexible battery is bent , The workability is increased, the energy density loss is minimized, and the bending durability and safety are improved.
상기와 같은 목적을 달성하기 위한 본 발명의 일 관점에 따른 전극 조립체는 분리막을 사이에 두고 상이한 극성을 갖는 한 쌍의 전극판을 갖는 하나 이상의 단위셀; 상기 한 쌍의 전극판의 단면 또는 양면 상에 도포되는 전극 합제; 및 상기 전극판의 가장자리에 위치하는 동시에 상기 전극 합제가 미도포된 상태의 전극 탭;을 포함하고, 상기 전극 탭은 전극 병렬 연결용 탭과 전극 리드 연결용 탭을 포함하고, 상기 전극판은 상기 전극 병렬 연결용 탭과 전극 리드 연결용 탭 중 어느 하나 이상의 전극 탭이 형성되며, 전극조립체의 최외곽 전극판은 음극이 배치되어 적층된다.According to an aspect of the present invention, there is provided an electrode assembly comprising: at least one unit cell having a pair of electrode plates having different polarities with a separator interposed therebetween; An electrode material mixture applied on one or both surfaces of the pair of electrode plates; And an electrode tab positioned at an edge of the electrode plate and not yet coated with the electrode mixture, wherein the electrode tab includes an electrode parallel connection tab and an electrode lead connection tab, At least one of electrode tabs for electrode parallel connection and tabs for electrode lead connection is formed and the outermost electrode plate of the electrode assembly has a cathode arranged and stacked.
상기 최외곽 전극판은 상기 전극 병렬 연결용 탭과 상기 전극 리드 연결용 탭을 모두 포함한다.The outermost electrode plate includes both the electrode parallel connection tab and the electrode lead connection tab.
상기 전극 병렬 연결용 탭만을 포함한 상태에서 상이한 극성을 갖는 한 쌍의 전극판은, 상기 한 쌍의 전극판 중 음극판 상에 도포된 음극합제의 면적은 양극판 상에 도포된 양극합제의 면적보다 크게 설정되며, 이러한 이유로 상기 음극합제의 모서리는 상기 양극합제의 모서리를 기준으로 5mm 이내 범위에서 외측으로 벗어나도록 설정되며, 단위면적 당 양극 용량에 대한 단위면적 당 음극 용량은 1 내지 1.2 배 이다.A pair of electrode plates having different polarities in a state including only the electrode-parallel connection tab is formed such that the area of the negative electrode mixture applied on the negative electrode plate of the pair of electrode plates is set larger than the area of the positive electrode mixture applied on the positive electrode plate For this reason, the edge of the negative electrode mixture is set to deviate outward within 5 mm from the edge of the positive electrode mixture, and the negative electrode capacity per unit area per unit area is 1 to 1.2 times.
상기 전극 병렬 연결용 탭만을 포함한 음극판과 상기 전극 병렬 연결용 탭과 상기 리드 연결용 탭을 모두 포함하는 양극판이 분리막을 사이에 두고 대면한 상태에서, 상기 전극 병렬 연결용 탭만을 포함한 음극판 상에 도포된 음극합제 면적이 상기 전극 병렬 연결용 탭과 상기 리드 연결용 탭을 모두 포함하는 양극판의 면적보다 크게 설정되며, 이러한 이유로 상기 전극 병렬 연결용 탭만을 포함한 음극판의 모서리는 상기 양극합제의 모서리를 기준으로 외측으로 벗어나도록 설정되고, 상기 양극판에 형성된 탭-리드 결합부를 상기 전극 병렬 연결용 탭만을 포함한 음극판이 덮는 형태이다.The positive electrode plate including only the tab for electrode parallel connection and the positive electrode plate including both the electrode parallel connection tab and the lead connection tab face each other with the separator interposed therebetween, The edges of the negative electrode plate including only the tabs for connecting electrodes for parallel connection are set to be larger than the edges of the positive electrode plate including the electrode connecting tabs and the lead connecting tabs, And the negative electrode plate including only the tab for electrode parallel connection covers the tab-lead coupling portion formed on the positive electrode plate.
상기 전극 조립체의 전극들 중 최상단 및 최하단에 배치된 최외곽 음극판은 전극 합제가 단면 도포될 수 있다.The electrode assembly may be applied to the outermost negative electrode plate disposed at the uppermost and lowermost ends of the electrodes of the electrode assembly.
상기 전극 조립체는, 상기 전극 조립체를 구성하는 전극 탭 중 어느 하나의 전극 리드 연결용 탭 상에 용착 고정된 보강 탭;을 더 포함한다.The electrode assembly further includes a reinforcing tab welded and fixed on one of the electrode tabs of the electrode tabs constituting the electrode assembly.
상기 전극 조립체를 구성하는 전극 탭 중 어느 하나의 전극 리드 연결용 탭 상에 결합된 전극 리드는 상기 전극 조립체를 향하도록 접합된 상태에서 180˚ 반대 방향으로 굽혀져 상기 전극 조립체의 외측 방향으로 향한 굽힘 구조를 더 포함한다.The electrode leads connected to the electrode lead connecting tabs of the electrode tabs constituting the electrode assembly are bent in the direction opposite to that of the electrode assembly in the direction opposite to the electrode assembly to be bent toward the outward direction of the electrode assembly, Structure.
상기 전극 리드 연결용 탭과 전극 리드를 상기 보강 탭을 이용하여 덧대어진 구조의 탭 리드 결합부는 상기 분리막의 내측으로 삽입 정렬하여 배치된 상태이다.And the tab lead connecting portions of the electrode lead connecting tabs and the electrode leads are padded by using the reinforcing tabs are arranged and arranged inside the separating film.
상기 전극 리드 연결용 탭과 굽힘 구조의 전극 리드가 결합된 탭-리드 결합부는 상기 분리막의 내측으로 삽입 정렬하여 배치된 상태이다.The tab-and-lid coupling portion, in which the electrode lead connecting tab and the electrode lead of the bending structure are coupled, is inserted and aligned inwardly of the separating membrane.
상기와 같은 목적을 달성하기 위한 본 발명의 다른 관점에 따른 리튬이온 이차전지는 전극 조립체; 및 상기 전극 조립체를 감싸는 외장재;를 포함하고, 상기 외장재부는 상기 전극 조립체의 외부를 둘러싸도록 상부 압인부와 하부 압인부가 반복 압인 가공된 구조이다.According to another aspect of the present invention, there is provided a lithium ion secondary battery comprising: an electrode assembly; And an outer casing surrounding the electrode assembly. The outer casing is a structure in which the upper and lower depressions are repeatedly pressed to surround the outer surface of the electrode assembly.
상기 복수의 상부 압인부와 하부 압인부는 상기 전극조립체 및 외장재부의 폭과 평행한 방향으로 연속적으로 형성된다.The plurality of upper crimping portions and the lower crimping portion are continuously formed in a direction parallel to the widths of the electrode assembly and the covering member.
본 발명에 따르면, 분리막을 통해 상하로 적층되는 복수의 전극을 갖는 전극 조립체에서 적어도 하나 이상의 전극은 전극 병렬 연결용 탭과 전극 리드 연결용 탭을 포함하도록 전극 조립체를 구성하며, 최외곽 전극을 음극으로 배치하는 구조 개선을 통해 플렉서블한 환경에서 외부의 반복적인 굽힘과 비틀림 등에 의해 발생할 수 있는 전지의 기계적 문제인 전극 및 전극 단자의 파손을 방지한다. 또한, 최상단과 최하단의 최외곽 전극을 음극으로 하여 작업성을 높임과 동시에 에너지 밀도 손실을 최소화하고, 굽힘 내구성 및 안전성을 향상시킨다.According to the present invention, in an electrode assembly having a plurality of electrodes stacked up and down through a separator, at least one electrode constitutes an electrode assembly including a tab for electrode parallel connection and a tab for electrode lead connection, To prevent breakage of the electrode and the electrode terminal, which are mechanical problems of the battery, which may occur due to external bending and torsion in the external environment in a flexible environment. In addition, the uppermost and lowermost outermost electrodes serve as cathodes to increase workability, minimize energy density loss, and improve bend durability and safety.
도 1은 본 발명에 따른 플렉서블 전지를 구성하는 전극 조립체의 예시적인 구성을 보인다.1 shows an exemplary structure of an electrode assembly constituting a flexible battery according to the present invention.
도 2는 본 발명의 실시예에 따라 전극조립체의 최외곽 전극을 음극으로 배치한 상태의 전극 조립체의 분해도를 보인다.FIG. 2 is an exploded view of an electrode assembly in which an outermost electrode of an electrode assembly is disposed as a cathode according to an embodiment of the present invention.
도 3 및 도 4는 전극 조립체를 구성하는 복수의 전극 및 상기 복수의 전극 사이에 배치되는 분리막의 배치 구조를 보인다.FIGS. 3 and 4 show the arrangement structure of a plurality of electrodes constituting the electrode assembly and a separation membrane disposed between the plurality of electrodes.
도 5a 내지 도 5f는 전극조립체의 최외곽 전극을 양극으로 배치한 상태와 음극으로 배치한 상태의 다양한 전극 조립체의 분해도를 보인다.5A to 5F show exploded views of various electrode assemblies in a state where the outermost electrodes of the electrode assembly are arranged as an anode and as a cathode.
도 6은 전극조립체의 최외곽 전극을 양극으로 배치한 상태에서 내부의 음극과 양극의 합제의 면적에 의해 충방전 과정 중에서 음극 상에 리튬 금속이 석출되는 상태를 보인다.FIG. 6 shows a state in which lithium metal is precipitated on the cathode during charging and discharging by the area of the mixture of the cathode and the anode in the state where the outermost electrode of the electrode assembly is disposed as an anode.
도 7은 본 발명에 따라 전극 병렬 연결용 탭만을 포함한 상태에서 상이한 극성을 갖는 한 쌍의 전극판 상에 도포된 음극합제 및 양극합제의 면적을 보인다.FIG. 7 shows areas of a negative electrode mixture and a positive electrode mixture applied on a pair of electrode plates having different polarities in a state including only a tab for electrode parallel connection according to the present invention.
도 8은 상기 전극 병렬 연결용 탭만을 포함하는 음극판과 전극 병렬 연결용 탭과 리드 연결용 탭을 모두 포함하는 양극판 상의 음극합제 및 양극합제의 면적을 보인다.FIG. 8 shows the areas of the negative electrode mixture and the positive electrode mixture on the positive electrode plate including both the negative electrode plate including only the tab for electrode parallel connection and the tab for connecting in parallel with the electrode and the lead connecting tab.
도 9는 전극 조립체 및 상기 전극 조립체를 감싸는 외장재부를 갖는 플렉서블 전지를 보인다.Fig. 9 shows a flexible battery having an electrode assembly and a covering member surrounding the electrode assembly.
도 10은 플렉서블 전지를 이루는 외장재부에 있어서, 상기 외장재부의 폭과 평행한 방향으로 상부 압인부 및 하부 압인부 등의 패턴이 형성된 모습을 보인다.10 shows a state in which a pattern such as an upper pressing portion and a lower pressing portion is formed in a direction parallel to the width of the exterior material portion in the exterior material portion constituting the flexible battery.
도 11은 외장재부에 형성된 상부 압인부 및 하부 압인부의 구체적인 형태를 설명한다.FIG. 11 illustrates a specific shape of the upper and lower pressing portions formed on the casing member.
도 12는 본 발명의 실시예에 따라 전극조립체의 최외곽 전극을 음극으로 배치한 경우, 최외곽 전극을 양극으로 배치한 경우 및 일반적인 전지 조합의 경우에, 충방전에 따른 벤딩 사이클을 보이는 그래프이다.12 is a graph showing a bending cycle according to charging and discharging when the outermost electrode of the electrode assembly is arranged as a cathode, the outermost electrode is arranged as an anode, and a general battery is combined according to an embodiment of the present invention .
도 13a 내지 도 13c는 본 발명의 전극 폭과 리드 연결용 탭의 폭에 따른 실시예를 설명하기 위한 도면이다.13A to 13C are views for explaining an embodiment according to the electrode width and the width of the tab for lead connection according to the present invention.
도 14는 본 발명의 일 실시예에 따라 전극을 적층함으로써 전지의 유연성을 향상시키기 위한 방법을 설명하기 위한 도면이다.14 is a view for explaining a method for improving the flexibility of a battery by stacking electrodes according to an embodiment of the present invention.
도 15는 본 발명의 일 실시예에 따라 전극조립체의 최외곽 전극이 양극인 경우와 음극인 경우로 구분하고, 여기에 전극리드 연결용 탭의 폭을 서로 상이하게 구성하여 조합한 전극 조립체들을 제작하였고, 제작한 각각의 전극 조립체로 구성된 전지의 벤딩 평가 결과를 나타낸 그래프이다.FIG. 15 is a sectional view of an electrode assembly according to an embodiment of the present invention. Referring to FIG. 15, the electrode assemblies are assembled by forming the outermost electrodes of the electrode assembly into an anode and a cathode, And a bending evaluation result of a battery composed of the electrode assemblies produced.
이하, 첨부된 도면을 참조하여 본 발명에 따른 플렉서블 전지에 대하여 설명하기로 한다. Hereinafter, a flexible battery according to the present invention will be described with reference to the accompanying drawings.
이하의 실시예는 본 발명의 이해를 돕기 위한 상세한 설명이며, 본 발명의 권리 범위를 제한하는 것이 아님은 당연할 것이다. 따라서, 본 발명과 동일한 기능을 수행하는 균등한 발명 역시 본 발명의 권리 범위에 속할 것이다. The following examples are intended to illustrate the present invention and should not be construed as limiting the scope of the present invention. Accordingly, equivalent inventions performing the same functions as the present invention are also within the scope of the present invention.
또한, 각 도면의 구성요소들에 참조부호를 부가함에 있어서, 동일한 구성요소들에 대해서는 비록 다른 도면상에 표시되더라도 가능한 한 동일한 부호를 가지도록 하고 있음에 유의해야 한다. 또한, 본 발명을 설명함에 있어, 관련된 공지 구성 또는 기능에 대한 구체적인 설명이 본 발명의 요지를 흐릴 수 있다고 판단되는 경우에는 그 상세한 설명은 생략한다.In addition, in adding reference numerals to the constituent elements of the respective drawings, it should be noted that the same constituent elements are denoted by the same reference numerals even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.
도 1 및 도 2를 참조하여, 본 발명에 따른 전극조립체의 최외곽 전극을 음극으로 배치한 상태의 전극 조립체의 일 실시예를 설명한다.1 and 2, an embodiment of an electrode assembly in which an outermost electrode of an electrode assembly according to the present invention is disposed as a cathode will be described.
전극 조립체는 음극판(10)과 양극판(20), 음극판과 양극판 사이에서 이온 전달 매개체 역할을 하는 전해액, 전극판의 가장자리에 위치하며 용도에 따라 분리되는 전극 병렬 연결용과 전극 리드 연결용으로 나뉘는 전극 탭을 포함한다. 상기 음극판(10)과 양극판(20)을 포함하는 전극판들 중 어느 하나 이상의 전극판은 전극 병렬 연결용 탭과 전극 리드 연결용 탭을 양측에 이격 배치할 수 있다. 예를 들어, 전극 조립체(100)의 최상단 또는 최하단에 배치되는 임의의 음극판(10)은 음극 병렬 연결용 탭(12)과 음극 리드 연결용 탭(14)을 구비하고, 상기 임의의 음극판(10)과 대면하며 분리막을 경계로 배치된 임의의 양극판(20)은 양극 병렬 연결용 탭(22)과 양극 리드 연결용 탭(24)을 구비한다.The electrode assembly includes an anode plate 10 and an anode plate 20, an electrolyte solution serving as an ion transfer medium between the anode plate and the anode plate, an electrode tab located at the edge of the electrode plate, . Any one or more of the electrode plates including the negative electrode plate 10 and the positive electrode plate 20 may be disposed on both sides of the tab for electrode parallel connection and the tab for electrode lead connection. For example, an optional cathode plate 10 disposed at the uppermost or lowermost end of the electrode assembly 100 has a cathode-parallel connection tab 12 and a cathode lead connection tab 14, and the optional cathode plate 10 And the optional positive electrode plate 20 disposed at the boundary of the separator has the positive electrode parallel connection tab 22 and the positive electrode lead connection tab 24.
여기에서, 전극판들은 전극 집전체의 단면 또는 양면에 전극 합제가 도포되어진 형태이며, 상기 전극 병렬 연결용 탭 및 전극 리드 연결용 탭은 전극 합제가 미도포된 상태로 전극 집전체가 노출된 형태이다.Here, the electrode plates are in the form of an electrode mixture applied on one or both surfaces of the electrode current collector, and the tabs for electrode parallel connection and the tabs for electrode lead connection are formed in such a manner that the electrode current collector is exposed to be.
상기 복수의 전극판들은 전극 병렬 연결용 전극 탭을 통해 동일한 극끼리 연결된다. 즉, 복수의 음극판(10)들 및 복수의 양극판(20)들은 각각 전극 탭들 간을 연결하는 탭-탭 결합부에 의해서 전기적으로 병렬 연결된다. The plurality of electrode plates are connected to each other through the electrode tabs for electrode parallel connection. That is, the plurality of negative electrode plates 10 and the plurality of positive electrode plates 20 are electrically connected in parallel by the tab-to-tab joints connecting the electrode tabs.
한편, 전극 조립체의 전극 리드 연결용 탭과 전극 리드간 전기적 연결을 통해 전극 조립체에서 외장재 외부로 전자를 이동시키는 경로를 제공할 수 있게 된다. 분리막은 극성이 서로 다른 전극판 사이에 위치시킬 수 있으며, 전자의 흐름을 차단하지만 전해액에 포함된 이온은 통과시키는 기능을 한다.Meanwhile, it is possible to provide a path for moving electrons from the electrode assembly to the outside of the casing through electrical connection between the electrode lead connecting tab and the electrode lead. The separator can be positioned between the electrode plates having different polarities and functions to block the flow of electrons but to pass ions contained in the electrolyte.
음극판(10) 또는 양극판(20) 상의 가장자리에 형성되는 전극 병렬 연결용 탭(12, 22)은 동일한 극성의 전극판들은 서로 전기적으로 병렬 연결하게 한다. 병렬 연결된 탭-탭 결합부는 전극 조립체의 최상단 또는 최하단을 이루는 최외각 전극판의 외면을 감싸고 있는 분리막 상에 위치하여 마감 테이핑처리된다. The tabs 12 and 22 for parallel connection of the electrodes formed on the edge of the anode plate 10 or the anode plate 20 allow the electrode plates of the same polarity to be electrically connected in parallel with each other. The tab-to-tab joints connected in parallel are positioned on the separation membrane that surrounds the outer surface of the outermost electrode plate forming the uppermost or lowermost end of the electrode assembly, and subjected to finish taping.
본 발명에서 전극판에 형성된 전극 병렬 연결용 탭(12, 22)이 서로 결합된 탭-탭 결합부 및 전극 리드 연결용 탭(14, 24)과 전극 리드가 서로 결합된 탭-리드 결합부는 스팟 전기 용접, 초음파 용접, 레이저 용접 및 도전성 접착제에 의한 결합을 포함하는 접합 방식 중 어느 하나를 통해 전기적으로 연결된다.In the present invention, the tab-to-tab connecting portion and the electrode lead connecting tabs (14, 24), which are formed on the electrode plate with the tabs (12, 22) for electrode parallel connection, And is electrically connected through any of the bonding methods including bonding by electric welding, ultrasonic welding, laser welding, and conductive adhesive.
도 3을 참조하면, 분리막(30)을 사이에 두고 음극판(10)과 양극판(20)이 연속적으로 적층된 상태에서, 상기 분리막은 전극 조립체의 외곽을 전체적으로 감싸는 지그재그 적층 형태일 수 있다. 기존의 음극판과 양극판이 단순히 적층되는 방식은 외부의 굽힘 및 비틀림 등에 의해 전극 조립체 내의 전극과 분리막들의 이탈과 오정렬에 의해 리튬 석출 및 내부 단락 문제가 발생하여 안전성이 떨어진다. 하지만 본 발명에서는 지그재그 적층 방식과 병렬 연결용 탭들이 전기적으로 연결된 탭-탭 결합부가 전극조립체 내 전극들을 잡아주기 때문에 플렉서블한 환경에서도 이탈과 오정렬을 최소화하는 효과가 있다.Referring to FIG. 3, the separator may be a zigzag laminate in which the cathode plate 10 and the anode plate 20 are continuously stacked with the separator 30 interposed therebetween. The conventional method of simply laminating the negative electrode plate and the positive electrode plate causes safety problems due to lithium precipitation and internal short circuit due to deviation and misalignment of electrodes and separators in the electrode assembly due to external bending and twisting. However, according to the present invention, since the tab-to-tab joint electrically connecting the zigzag lamination method and the parallel connection tabs catches the electrodes in the electrode assembly, it is possible to minimize separation and misalignment even in a flexible environment.
도 4를 참조하면, 이는 지그재그 적층한 전극들의 면적 비교와 구조 이해를 돕기 위해 펼친 상태를 보인다. 전극 조립체의 일측에 배치된 전극 리드 연결용 탭(14,24) 상에는 별도의 보강 탭(70)을 보강할 수 있다. 상기 보강 탭(70)에 전극 리드(60)를 결합함으로써 전극 리드 연결용 탭(14,24)과 전극 리드(60)를 보강 탭(70)을 이용하여 덧댐 구조의 탭-리드 결합부(50)를 형성한다. 보강 탭(70)을 이용하여 전극 리드 연결용 탭(14,24)과 전극 리드(60)를 결합하는 보강 접합 방식은 양극 탭 및 음극 탭 중 적어도 어느 하나에 해당한다.Referring to FIG. 4, this shows an expanded state in order to compare the area of the zigzag stacked electrodes and to understand the structure. A separate reinforcing tab 70 can be reinforced on the electrode lead connecting tabs 14 and 24 disposed on one side of the electrode assembly. The electrode lead connecting tabs 14 and 24 and the electrode lead 60 are connected to the tab-and-lid connecting portion 50 of the overtight structure by using the reinforcing tabs 70 by coupling the electrode leads 60 to the reinforcing tabs 70 ). The reinforcing bonding method for bonding the electrode lead connecting tabs 14 and 24 to the electrode lead 60 using the reinforcing tab 70 corresponds to at least one of the positive electrode tab and the negative electrode tab.
상기 보강 탭(70)은 전극 리드 연결용 탭(14,24)과 전극 리드(60)의 연결 부분의 강도를 보강함으로써 물리적으로 강화한다. 예시적으로, 전극 조립체의 전극판에서 연장되는 전극 리드 연결용 탭 상단에 상기 전극 리드 연결용 탭보다 1배 내지 5배 두꺼운 동종 또는 이종의 금속 보강 탭(70)을 덧댐으로 보강시켜 용착한다. 덧댐으로 보강된 보강 탭(70) 및 전극 리드 연결용 탭은 동일 또는 상이한 폭을 갖는다. 보강되는 보강 탭(70)의 폭은 3 ㎜ 내지 5 ㎜, 길이는 2 ㎜ 내지 4 ㎜일 수 있지만, 이는 일 실시예 일 뿐 이에 한정하는 것은 아니다.The reinforcing tab 70 is physically reinforced by reinforcing the strength of the connection portion between the electrode lead connecting tabs 14 and 24 and the electrode lead 60. For example, the same or different metal reinforcing tabs 70, which are 1 to 5 times thicker than the electrode lead connecting tabs, are welded to the upper ends of the tabs for electrode lead connection extending from the electrode plates of the electrode assembly. The reinforcing tabs 70 reinforced by the overhangs and the tabs for connecting the electrode leads have the same or different widths. The reinforcing tab 70 may have a width of 3 mm to 5 mm and a length of 2 mm to 4 mm, but this is not limitative.
덧댐으로 보강된 보강 탭(70) 상에 접합함으로써 전극 리드 연결용 탭과 결합하는 전극 리드는 구체적으로 2 ㎜ 내지 3 ㎜의 폭 및 0.5 ㎜ 내지 1 ㎜의 길이를 가질 수 있지만, 이는 일 실시예 일 뿐 이에 한정하는 것은 아니다. 본 발명에서 전극판의 집전체는 알루미늄, 스테인레스 스틸 및 구리를 포함하는 그룹 중 어느 하나일 수 있고, 전극 리드는 알루미늄, 니켈 및 니켈이 코팅된 구리를 포함하는 그룹 중 어느 하나의 재질을 가질 수 있다. 전극 리드 연결용 탭과 전극 리드의 탭-리드 결합부 상에 덧댐으로 보강시키는 보강 탭은 원, 타원 및 다각형을 포함하는 그룹 중 1개의 모양으로 형성된다.The electrode leads, which are joined to the electrode lead connecting tabs by bonding on the reinforcing tabs 70 reinforced by the overhang, may have a width of 2 mm to 3 mm and a length of 0.5 mm to 1 mm, But is not limited thereto. In the present invention, the current collector of the electrode plate may be any one of a group including aluminum, stainless steel, and copper, and the electrode lead may have any one material selected from the group consisting of aluminum, nickel, and nickel coated with nickel have. The tabs for electrode lead connection and the reinforcing tabs to be reinforced by the overhang on the tab-lead connection portion of the electrode lead are formed in one of the group including circle, ellipse and polygon.
또한, 전극 조립체를 구성하는 전극 탭 중 어느 하나의 전극 리드 연결용 탭 상에 결합된 전극 리드는 상기 전극 조립체를 향하도록 접합된 상태에서 180˚ 반대 방향으로 굽혀져 상기 전극 조립체의 외측 방향으로 향한 굽힘 탭(80) 구조를 형성할 수 있다. 이는 플렉서블한 환경에서 국부적인 기계적 부하를 최소화하여 전극 탭과 전극 리드 간의 결합 보강 구조의 특징을 갖는다. 전극 리드 연결용 탭과 전극 리드(60)의 굽힘을 통한 접합 방식은 양극 탭 및 음극 탭 중 적어도 어느 하나에 해당할 수 있고, 전극 리드 연결용 탭 상에 결합되는 전극 리드(60)의 폭은 2 ㎜ 내지 3 ㎜, 길이는 1 ㎜ 내지 3 ㎜일 수 있지만, 이는 일 실시예일뿐 이에 한정하는 것은 아니다.Also, the electrode leads connected to the electrode lead connecting tabs of the electrode tabs constituting the electrode assembly are bent in the direction opposite to the direction of 180 ° in the state of being joined to the electrode assembly, The bending tab 80 structure can be formed. This is characterized by a joint reinforcing structure between the electrode tabs and the electrode leads by minimizing the local mechanical load in a flexible environment. The electrode lead connecting tabs and the electrode leads 60 may be bonded to each other by bending. The width of the electrode leads 60 connected to the electrode lead connecting tabs may be at least one of 2 mm to 3 mm, and a length of 1 mm to 3 mm, but this is not limitative.
한편, 전극 리드 연결용 탭(14, 24)과 전극 리드(60)를 보강 탭(70)을 이용하여 결합한 탭-리드 결합부(50) 및 전극 리드 연결용 탭과 굽힘 탭(80) 구조의 전극 리드(60)가 결합된 탭-리드 결합부(50)는 분리막의 내측으로 삽입/정렬된, 즉 내측으로 배치된 상태를 갖는다. 이를 통해 플렉서블 전지의 최대 약점인 단자 부분의 외부노출을 방지함으로써 보호시킨다.A tab-and-lid connection portion 50 is formed by combining the electrode lead connecting tabs 14 and 24 and the electrode lead 60 by using the reinforcing tabs 70 and the electrode lead connecting tabs and bend tabs 80 The tab-and-lid engagement portion 50 to which the electrode lead 60 is joined has a state in which it is inserted / aligned inwardly of the separator, that is, inwardly disposed. This protects the flexible battery by preventing external exposure of the terminal part, which is the weakest point of the flexible battery.
도 4 상에서, 전극리드 연결용 탭과 병렬 연결용 탭이 동시에 구비된 전극(B, B')은 전극 병렬 연결용 탭만을 구비한 전극(C)에 비해 도포되는 합제층의 면적이 작다.In FIG. 4, the electrodes B and B 'provided with the electrode lead connecting tab and the parallel connecting tab are smaller in area than the electrode C having only the electrode connecting tab.
더불어, 전극(B, B') 중 외측에 배치된 전극(B)의 합제층 면적이 내측에 배치된 전극(B')의 합제층 면적보다 크게 된다. 이를 통해, 음극의 모서리 부근에 석출되는 금속 리튬 발생을 줄일 수 있다.In addition, the mixed layer area of the electrode (B) disposed on the outer side of the electrodes (B, B ') is larger than the mixed layer area of the electrode (B') disposed on the inner side. As a result, generation of metal lithium precipitated in the vicinity of the edge of the negative electrode can be reduced.
본 발명에서 상기 전극(B)은 음극인 최외곽 전극에 해당하고, 전극(B')은 상기 최외곽 전극과 분리막을 경계로 하여 대면하는 양극 전극판이다. 즉, 전극 조립체 상에서 최하층에는 음극인 전극(B)가 배치되고, 상기 전극(B)의 바로 상단에 양극인 전극(B')가 배치된다. 상기 전극(B')의 상단으로는 음극인 전극 병렬 연결용 탭만을 구비한 전극(C)이 배치된다. 한편, 상기 전극(B')와 전극(C) 사이에는 병렬 연결용 탭만 형성된 상태의 일반 전극들이 추가로 배치될 수 있다.In the present invention, the electrode (B) corresponds to the outermost electrode which is the cathode, and the electrode (B ') is the anode electrode plate which faces the outermost electrode and the separator. That is, an electrode B as a cathode is disposed on the lowest layer on the electrode assembly, and an electrode B 'as an anode is disposed immediately above the electrode B. At the upper end of the electrode (B '), an electrode (C) having only a tab for electrode parallel connection which is a cathode is disposed. Meanwhile, general electrodes in a state in which only a parallel connection tab is formed may be additionally disposed between the electrode (B ') and the electrode (C).
도 5a 내지 도 5f는 전극조립체의 최외곽 전극을 양극으로 배치한 상태와 음극으로 배치한 상태의 다양한 전극 조립체의 분해도를 보인다. 5A to 5F show exploded views of various electrode assemblies in a state where the outermost electrodes of the electrode assembly are arranged as an anode and as a cathode.
도 6은 전극조립체의 최외곽 전극을 양극으로 배치한 상태에서 내부의 음극과 양극의 합제의 면적에 의해 충방전 과정 중에서 음극 상에 리튬 금속이 석출되는 상태를 보인다.FIG. 6 shows a state in which lithium metal is precipitated on the cathode during charging and discharging by the area of the mixture of the cathode and the anode in the state where the outermost electrode of the electrode assembly is disposed as an anode.
플렉서블 전지의 벤딩과정에서 가장 파단되기 쉬운 전극 탭/리드 결합부의 손상을 방지하기 위한 방법으로, 상기 전극 탭/리드 결합부를 전극 외부로 노출시키지 않고 전극 내부에 위치시킨다. 이를 위한 가장 효과적인 방법은, 전극 병렬 연결용 탭만을 구비한 전극에 비해 전극 병렬 연결용 탭과 전극 리드 연결용 탭을 동시에 구비한 전극에 도포되는 합제층의 면적을 작게 하는 것일 수 있다.A method for preventing damage to an electrode tab / lead coupling portion that is most likely to break during the bending process of the flexible battery, the electrode tab / lead coupling portion is positioned inside the electrode without being exposed to the outside of the electrode. The most effective way to accomplish this is to reduce the area of the mixed layer applied to the electrode having the electrode-parallel connection tab and the electrode lead connection tab at the same time as compared with the electrode having only the electrode-parallel connection tab.
도 5a 내지 도 5b 및 도 6과 같이, 최외곽 전극을 양극으로 배치하는 경우에는 전극리드 연결용 탭이 형성된 음극에 대면하는 양극의 합제층 면적도 따라서 작아져야 한다. 상기와 같은 이유는 그렇지 않을 경우에 충전 시에 양극에서 빠져나온 리튬이 음극 모서리 부근에 석출되어 용량과 효율이 감소하고 저항이 커지는 동시에, 석출된 리튬이 침상으로 성장하여 분리막 손상을 유발, 전지 내부에 단락(internal short)이 발생하기 때문이다.As shown in FIGS. 5A to 5B and 6, when the outermost electrode is disposed as an anode, the area of the mixed layer of the anode facing the cathode having the electrode lead connecting tab should be reduced accordingly. The reason for this is that if not, the lithium extracted from the anode at the time of charging precipitates in the vicinity of the edge of the cathode to decrease the capacity and efficiency and increase the resistance, and the precipitated lithium grows into a needle- (Internal short) occurs.
도 5a를 참조하면, 전극조립체의 최외곽 전극이 양극인 경우, 최외곽 양극은 단면으로 코팅되어 있어야 하며, 중간층에 위치한 양극의 경우, 양극활물질이 포함된 양극합제 도포층이 음극활물질이 포함된 음극합제 도포층과 전체면적에서 대면하도록 합제 미도포 영역을 구비해야 한다.Referring to FIG. 5A, when the outermost electrode of the electrode assembly is a cathode, the outermost anode should be coated in a cross section, and in the case of the anode located in the middle layer, the cathode mixture coating layer containing the cathode active material includes the anode active material It is necessary to provide an uncombusted area so as to face the negative electrode mixture layer at the entire area.
또한, 도 5b를 참조하면, 다른 해결방법으로, 최외곽 양극은 단면으로 코팅되어 있어야 하며, 전극 병렬 연결용 탭과 전극 리드 연결용 탭을 동시에 구비한 음극과, 전극 병렬 연결용 탭만을 구비한 음극 사이에 위치하며 전극 리드 연결용 탭을 구비하지 않은 양극의 경우, 전극 병렬 연결용 탭만을 구비한 다른 양극보다 크기가 작아져야 한다. 즉, 양극 합제층이 배치되어야 할 일부(501)의 영역을 활용하지 못함으로 인해 에너지밀도가 낮아지게 된다. 또한, 전극들이 적층된 전극 조립체의 두께방향 기준으로, 음극 리드/탭 결합부 주변에서 두께 단차가 커지게 되어, 상기 결합부의 파손으로 인한 플렉서블 전지의 벤딩시 품질을 저하시킬 수 있다.5B, in another solution, the outermost anode has to be coated in a cross-section, and a cathode having both a tab for electrode-parallel connection and a tab for electrode lead connection and a tab for electrode- In the case of an anode which is located between the cathodes and does not have a tab for electrode lead connection, it should be smaller in size than the other anode having only the tab for connecting the electrodes in parallel. That is, the energy density is lowered due to the inability to utilize the region of the portion 501 where the anode mixture layer is to be disposed. Also, the thickness step is increased in the vicinity of the negative electrode lead / tab joint portion on the basis of the thickness direction of the electrode assembly in which the electrodes are stacked, thereby lowering the bending quality of the flexible battery due to breakage of the joint portion.
아울러, 도 5c를 참조하면, 음극과 양극이 비대면되어 있는 부분(502)에 전해액과 반응하지 않는 비활성 재료이면서, 이온의 흐름을 차단하는 아크릴계, 또는 우레탄계 등으로 구성되는 접착 테이프, 점착제, 수지 등의 플렉서블 부재(502)를 추가하여야 한다.5C, an adhesive tape composed of an inactive material that does not react with the electrolyte solution and an acrylic or urethane-based adhesive that blocks the flow of ions is attached to the portion 502 where the negative electrode and the positive electrode are not confronted with each other, A flexible member 502 such as a flexible printed circuit board or the like must be added.
그러나, 상술된 해결방법들은, 양극과 음극에 병렬 연결용 탭만 구비한 전극, 리드 연결용 탭까지 모두 구비한 전극 등 여러 크기와 종류로 전극을 제조해야 하고, 양극과 음극이 닿는 면을 모두 고려해 설계, 관리해야 하며, 추가 소재를 사용해야 하므로 공정성이 매우 낮아 제조 단가가 높아지게 되고, 에너지 밀도가 낮아지게 된다.However, the above-described solutions require that electrodes be manufactured in various sizes and types, such as electrodes with only tabs for parallel connection to the positive and negative electrodes, and electrodes with leads to the lead connection tabs, Design, and management, and the use of additional materials requires very low fairness, resulting in higher manufacturing costs and lower energy density.
또한, 도 5d 및 도 5e를 참조하면, 탭-리드 결합부, 즉 리드 연결용 탭과 병렬 연결용 탭이 동시에 구비된 전극들이 전극조립체의 전극들 중 최외곽 어느 한쪽으로 치우치지 않는 경우, 최외곽을 음극으로 배치하더라도 전극조립체의 내부에 배치되는 탭-리드 결합부로 인해, 도 5d에 나타낸 것과 같이 병렬 연결용 탭만을 구비한 양극들의 크기를 서로 상이하게 하여 단차부(503)를 갖도록 구성되거나, 도 5e에 나타낸 것과 같이 양극활물질이 반응하지 않도록 합제층이 미도포된 부분(504)이 형성되어야 한다.5D and 5E, when the electrodes provided with the tab-lead coupling portion, that is, the lead connecting tab and the parallel connecting tab, are not shifted to one of the outermost electrodes of the electrode assembly, 5d, due to the tab-to-lead engaging portion disposed inside the electrode assembly even when the outer periphery is disposed as the cathode, the anodes having only the parallel connection tabs are made to have different sizes so as to have the stepped portions 503 , The untreated portion 504 should be formed so that the cathode active material does not react as shown in FIG. 5E.
그러나, 이는 양극과 음극에 병렬 연결용 탭만 구비한 전극, 전극리드 연결용 탭까지 모두 구비한 전극 등 여러 크기와 종류로 전극을 제조해야 하고, 양극과 음극이 닿는 면을 모두 고려해 설계, 관리해야 하므로 매우 공정성이 낮아져 제조 단가가 높아진다.However, it is necessary to manufacture electrodes of various sizes and types such as electrodes having only a tab for parallel connection to the anode and the cathode, and electrodes having both of the electrodes for connection to the lead electrode, and it is necessary to design and manage both the anode- So that the fairness is very low and the manufacturing cost is increased.
또한, 도 5f를 참조하면, 전극리드 연결용 탭이 전극조립체의 전극들 중 두께방향 최외곽 어느 한쪽이 아닌, 전극 조립체의 전극들 사이에 배치되는 경우, 전지 충전시 덴드라이트(Dendrite)가 발생하지 않도록 다양한 크기의 전극으로 나뉘어 제조, 관리해야 하는 문제가 있다.Referring to FIG. 5F, when the electrode lead connecting tab is disposed between the electrodes of the electrode assembly, not the outermost one of the electrodes in the thickness direction of the electrode assembly, a dendrite There is a problem in that it is necessary to manufacture and manage the electrodes by dividing them into electrodes of various sizes.
아울러, 전극 리드가 전극 조립체의 중간 부분에 배치되어 있을 경우, 내부 전극들의 두께 단차들(예를 들어, 505)로 인해 벤딩 및 트위스트와 같은 전지 사용 환경에서 내구성이 더욱 취약해진다. 따라서, 단차 발생부(505)에 가요성의 불활성 재료를 채워넣는 방법 등으로 단차 발생부(505)를 보완해 주지 않으면, 기계적 강성 및 연성이 취약한 부분에서 크랙 및 절단이 발생하여 성능이 저하되거나 구동이 불가능한 문제를 유발한다.In addition, when the electrode leads are disposed in the middle portion of the electrode assembly, the thicknesses of the internal electrodes (for example, 505) make the durability more vulnerable to battery usage such as bending and twisting. Therefore, unless the step difference generating portion 505 is supplemented by a method of filling the step difference generating portion 505 with a flexible inert material or the like, cracks and cuts may occur at portions where the mechanical rigidity and ductility are weak, This causes an impossible problem.
즉, 상술된 문제를 종합하여 보았을 때, 리드 연결용 탭이 구비된 전극과 전극리드는 전극조립체의 전극들 중 최외곽으로 치우쳐져서 설계되는 것이 바람직하다.In other words, it is preferable that the electrode having the lead connecting tab and the electrode lead are biased to the outermost one of the electrodes of the electrode assembly when the above-mentioned problems are considered.
또한, 도 6을 참고하면, 전극조립체의 최외곽 전극이 양극일 경우, 내부의 양극과 음극이 비대면하는 즉 양극합제층이 음극합제층을 넘어서는 경우(601) 특정 부위에 리튬 석출로 인한 성능저하 및 덴드라이트(Dendrite)로 인한 안전성 문제가 발생할 수 있다. 또한, 전극조립체의 최외곽 전극이 양면의 양극이 되면 외측의 양극합제층에서 리튬 이온이 음극 쪽으로 이동하여 반응하면서 안전성 문제를 유발하게 된다.6, when the outermost electrode of the electrode assembly is the anode, the anode and the cathode are not facing each other, that is, when the cathode mixture layer exceeds the anode mixture layer (601), the performance due to lithium precipitation Degradation and safety problems due to dendrite may occur. Also, when the outermost electrode of the electrode assembly becomes the positive electrode on both sides, lithium ions move toward the negative electrode in the positive electrode mixture layer on the outer side and react to cause a safety problem.
도 7 및 도 8에서 상기한 문제를 해소하기 위한 적절한 전극 합제층들의 면적 설계 방법을 도시하였다.In FIGS. 7 and 8, a method of designing an area of an electrode mixture layer suitable for solving the above-mentioned problem is shown.
또한, 상기한 현상을 막기 위해 용량 발현에 기여하는 양극의 합제층 면적을 작아지게 하면 그에 상응하여 에너지 밀도도 낮아지게 되므로 바람직하지 않다.Further, if the area of the positive electrode mixture layer contributing to capacity development is reduced to prevent the above-described phenomenon, the energy density becomes lower accordingly, which is not preferable.
한편으로, 양극의 합제층이 양면으로 도포되는 경우에는, 그 도포되는 면적을 달리해야 하는바, 제조 공정 상으로 공정능력이 떨어지는 문제가 발생하게 되므로, 본 발명에 따라 전극조립체의 최외곽 전극은 음극으로 구성하는 것이 바람직하다고 할 수 있다.On the other hand, when the positive electrode mixture layer is applied on both sides, the area to be coated must be different from that of the positive electrode, It can be said that it is preferable to constitute a cathode.
도 7은 전극 병렬 연결용 탭만을 포함한 상태에서 상이한 극성을 갖는 한 쌍의 전극판 중 음극판 상에 도포된 음극합제의 면적은 양극판 상에 도포된 양극합제의 면적보다 크게 설정되는 것을 보여준다. 양극합제의 모서리를 기준으로 음극합제와의 모서리의 차이(d)는 5 ㎜ 이내 범위에서 외측으로 벗어나도록 설계된다. 이때 단위 면적 당 양극 용량에 대한 단위 면적 당 음극 용량은 1 내지 1.2 배 이다.FIG. 7 shows that the area of the negative electrode mixture applied on the negative electrode plate among the pair of electrode plates having different polarities in the state including only the electrode parallel connection tab is set larger than the area of the positive electrode mixture applied on the positive electrode plate. The difference (d) between the edges of the anode mixture and the edge of the anode mixture is designed to deviate outward within a range of 5 mm. Here, the anode capacity per unit area with respect to the anode capacity per unit area is 1 to 1.2 times.
도 8은 전극 병렬 연결용 탭만을 포함한 음극판과 전극 병렬 연결용 탭과 리드 연결용 탭을 모두 포함하는 양극판이 분리막을 사이에 두고 대면한 상태에서, 전극 병렬 연결용 탭만을 포함한 음극판 상에 도포된 음극합제 면적이 전극 병렬 연결용 탭과 상기 리드 연결용 탭을 모두 포함하는 양극판의 면적보다 크게 설정되는 것을 보여준다. 양극합제의 모서리를 기준으로 음극합제와의 모서리의 차이(d)는 5 ㎜ 이내 범위에서 외측으로 벗어나도록 설계된다. 더 나아가, 플렉서블 전지에서 물리적으로 가장 취약한 부위인 전극 탭과 전극 단자 간의 연결부, 즉 양극판에 형성된 탭-리드 결합부(50)를 전극조립체의 분리막 내에 배치함으로써 취약부에서의 크랙이나 절단을 방지할 수 있게 된다. 이를 위해, 탭-리드 결합부(50)를 포함하는 양극판의 가장자리에 형성되는 동시에 양극합제가 미도포된 전극 탭의 길이(D)만큼 전극 병렬 연결용 탭만을 포함한 음극판이 크게 설계될 수 있다. 쉽게 설명하면, 전극 병렬 연결용 탭만을 포함하는 음극판이 전극 병렬 연결용 탭과 리드 연결용 탭을 모두 포함하는 양극판을 덮은 형상이 바람직하다. 이러한 구조를 통해 플렉서블 전지의 전극 탭-단자 결합부의 굽힘 내구성을 향상시킬 수 있다.FIG. 8 is a cross-sectional view of a positive electrode plate including only a tab for electrode parallel connection and a positive electrode plate including both a tab for electrode parallel connection and a tab for lead connection, The area of the negative electrode mixture is set larger than the area of the positive electrode plate including both the electrode-parallel connection tab and the lead connection tab. The difference (d) between the edges of the anode mixture and the edge of the anode mixture is designed to deviate outward within a range of 5 mm. Furthermore, by disposing the connection portion between the electrode tab and the electrode terminal, that is, the tab-lead coupling portion 50 formed on the positive electrode plate, in the separator of the electrode assembly, it is possible to prevent cracking or cutting in the weak portion . For this purpose, the negative electrode plate including only the tab for electrode parallel connection can be designed to be large by the length (D) of the electrode tab formed on the edge of the positive electrode plate including the tab-lead coupling portion 50 and uncoated with the positive electrode mixture. In other words, it is preferable that the negative electrode plate including only the tab for electrode parallel connection be covered with the positive electrode plate including both the electrode connection tab and the lead connection tab. With this structure, the bending durability of the electrode tab-terminal joint portion of the flexible battery can be improved.
도 9를 참조하면, 본 발명에 따른 전극 조립체는 상기 전극 조립체의 외부를 둘러싸도록 상부 압인부와 하부 압인부가 반복 압인 가공된 구조의 외장재부(200)를 배치한다.Referring to FIG. 9, the electrode assembly according to the present invention disposes the outer casing part 200 of the processed structure of the upper and lower pressing parts of the electrode assembly so as to surround the outer periphery of the electrode assembly.
도 10을 참조하면, 외장재부 상에 반복적으로 압인 가공된 복수의 상부 압인부와 하부 압인부는 굽힘, 비틀림 또는 구겨짐 동작에서 전극 조립체를 갖는 플렉서블 전지의 압축 및 인장이 가능하도록 패턴 및 형태가 반복된다.Referring to FIG. 10, the pattern and shape are repeated so as to enable compression and tensioning of a flexible battery having an electrode assembly in a bending, twisting or wrinkling operation, in which a plurality of upper depressing portions and lower depressing portions repeatedly stamped on the casing member are repeated .
상기 복수의 상부 압인부와 하부 압인부는 상기 전극 조립체 및 외장재부의 폭과 평행한 방향으로 연속적으로 형성될 수 있다.The plurality of upper depressions and lower depressions may be formed continuously in a direction parallel to the widths of the electrode assembly and the casing.
상기 복수의 상부 압인부와 하부 압인부는 각각 상부와 하부 금형으로 압인될 수 있다.The plurality of upper depressions and lower depressions may be depressed into upper and lower dies, respectively.
전극 조립체의 외부를 둘러싸는 외장재부는 실링부(230)의 붉은 점선을 기준으로 하여 상기 전극 조립체 상에서 상부 외장재부(210) 및 하부 외장재부(220)를 갖는 형태일 수 있다. 즉, 외장재부 상에 반복되는 복수의 상부 압인부(212, 222)와 하부 압인부(214, 224)는 실링부를 기준으로 대칭되는 구조로 형성되고, 상부 외장재부(210)와 하부 외장재부(220) 상에 대칭적으로 압인된다. 상기 상태에서, 상기 실링부를 상하 대칭적으로 절곡 후에 상기 외장재부 내부에 상기 전극 조립체를 수용하게 된다.The outer covering member surrounding the outer surface of the electrode assembly may have an upper casing member 210 and a lower casing member 220 on the electrode assembly with reference to a red dotted line of the sealing member 230. That is, the plurality of upper depression portions 212 and 222 and the lower depression portions 214 and 224 repeated on the casing member are formed symmetrically with respect to the ceiling portion, and the upper and lower casing members 210 and 210 220). ≪ / RTI > In this state, the electrode assembly is housed in the exterior member after the sealing portion is bent symmetrically upward and downward.
상기 상부 외장재부(210)와 하부 외장재부(220)를 구분하는 기준인 실링부의 폭은 3 ㎜ 내지 5 ㎜이고, 실제 실링 폭은 1 ㎜ 내지 2 ㎜ 일 수 있지만, 이는 일 실시예 일 뿐 이에 한정되는 것은 아니다. The width of the sealing portion, which is a reference for separating the upper and lower casing members 210 and 220, may be 3 mm to 5 mm and the actual sealing width may be 1 mm to 2 mm, But is not limited thereto.
도 11을 참조하면, 상기 외장재부 상에 반복되는 복수의 상부 압인부 높이(h)와 하부 압인부 높이(h')는 동일(h=h') 할 수 있다.Referring to FIG. 11, a plurality of repeated upper and lower heights h and h 'may be the same (h = h') on the outer casing.
상기 외장재부 상에 반복되는 복수의 상부 압인부 높이(h)와 하부 압인부 높이(h')는 0.5 ㎜ 내지 1 ㎜이며 최적값은 0.75 ㎜ 이지만, 이는 일 실시예일뿐 이에 한정하는 것은 아니다.A plurality of upper and lower repetition portions h and h 'are 0.5 mm to 1 mm and an optimum value is 0.75 mm. However, the present invention is not limited thereto.
한편, 상기 외장재부 상에 인접한 복수의 상부 압인부 최고점 간의 폭(a)과 복수의 하부 압인부 최저점 간의 폭(b)은 동일(a=b)하여 물결무늬 패턴을 형성한다.On the other hand, the width (a) between the plurality of upper peak portions of the upper shell and the width (b) between the lower peak portions of the lower peak portions adjacent to each other on the casing member are the same (a = b) to form a wave pattern.
본 발명은 분리막을 통해 상하로 적층되는 복수의 전극을 갖는 전극 조립체 중 최외곽 전극을 음극을 배치하여 플렉서블 전지의 굽힘 시에 전극 단자의 파손을 방지한다.The present invention is characterized in that a cathode is disposed on an outermost electrode of an electrode assembly having a plurality of electrodes stacked vertically through a separation membrane to prevent breakage of the electrode terminal when the flexible battery is bent.
도 12는 본 발명의 실시예에 따라 최외곽 전극을 음극으로 배치한 경우, 최외곽 전극을 양극으로 배치한 경우 및 전극 병렬 연결용 탭부와 전극 리드 연결용 탭부가 별도로 구성되지 않는 일반적인 전지 각각에 대한, 충방전과 동시에 수행하는 벤딩 횟수에 따른 전지 전압변화를 나타낸 그래프이다. 시험 조건은 곡률반경 25mm, 굽힘속도 분당 20회로 하여 반복 벤딩을 진행하면서 실시간으로 충전과 방전을 진행하며 전압을 모니터링한 결과이다 FIG. 12 is a graph showing the relationship between the outermost electrode as a cathode, the outermost electrode as an anode, the electrode parallel connection taps and the electrode lead connecting taps as separate cells according to an embodiment of the present invention. FIG. 3 is a graph showing changes in battery voltage according to the number of bending operations performed simultaneously with charging / discharging. The test conditions were charging and discharging in real time while repeating bending with a curvature radius of 25 mm and a bending rate of 20 cycles per minute and monitoring the voltage
도 12를 참조하면, 최외곽 전극 상에 음극을 적용하였을 때와 양극을 적용한 전지의 굽힘 평가 결과를 보인다. 상기한 일반전지의 경우에는 30회의 굽힘을 넘기지 못하고 전극 리드-탭 결합부가 파손되었다. 최외곽 전극이 양극으로 배치된 경우에는 3,800회 부근에서 전압 노이즈가 발생하였고, 이후 충전 중 급격한 전압 강하가 발생하였다. 반면에, 본 발명에 따라 최외곽 전극을 음극으로 적용한 경우에는 6,000회 이상의 굽힘에도 전극의 단자부분과 전극에 손상이 없었으며, 정상적인 전기화학구동을 보여주었다.Referring to FIG. 12, the results of bending evaluation of the negative electrode and the positive electrode are shown on the outermost electrode. In the case of the above-mentioned conventional battery, the electrode lead-tab joint portion was broken without exceeding 30 times of bending. When the outermost electrode was arranged as an anode, voltage noise occurred around 3,800 times, and then a sudden voltage drop occurred during charging. On the other hand, according to the present invention, when the outermost electrode was applied to the cathode, there was no damage to the terminal portion of the electrode and the electrode even when bending was performed over 6,000 times, and normal electrochemical actuation was shown.
즉, 본 발명에 따른 전극 조립체는 분리막을 포함하여 서로 상이한 극성을 갖는 양극과 음극이 차례로 적층되며, 이때 최상단과 최하단의 최외곽 전극을 음극으로 하여 공정성을 높임과 동시에 에너지 밀도 손실을 최소화하고, 굽힘 내구성 및 안전성을 향상시키는 효과가 있다.That is, the electrode assembly according to the present invention includes an anode and a cathode having different polarities in sequence, including a separator, in which the outermost electrode at the uppermost stage and the outermost electrode at the lowermost stage are used as cathodes to improve the processability, minimize the energy density loss, Bending durability and safety.
도 13a 내지 도 13c는 본 발명의 전극 폭과 리드 연결용 탭의 폭에 따른 실시예를 설명하기 위한 도면이다.13A to 13C are views for explaining an embodiment according to the electrode width and the width of the tab for lead connection according to the present invention.
도 13a를 참조하면, 제 1 전극(Electrode 1)의 전극 폭 및 리드 연결용 탭의 폭은 각각 Wn1, Wn2 이고, 제 2 전극(Electrode 2)의 전극 폭 및 리드 연결용 탭의 폭은 각각 Wp1, Wp2일 수 있다. 13A, the electrode width of the first electrode (Electrode 1) and the width of the lead connection tab are Wn1 and Wn2, the electrode width of the second electrode (Electrode 2) and the width of the lead connection tab are Wp1 , Wp2.
도 13a는 Wn2가 Wn1의 절반이상이고, Wp2가 Wp1의 절반이상인 경우를 설명하기 위한 도면이다. 본 실시예에 따르면, 이웃하는 각 전극의 전극 폭(Wn1, Wp1)이 동일한 경우, 이웃하는 각 전극의 리드 연결용 탭의 폭(Wn2, Wp2)은 전극 폭(Wn1, Wp1)의 절반이상으로 설계되어 각 전극 간에 일정 영역이 겹치도록 형성되어 배치될 수 있다. 13A is a diagram for explaining a case where Wn2 is at least half of Wn1 and Wp2 is at least half of Wp1. According to the present embodiment, when the electrode widths Wn1 and Wp1 of the neighboring electrodes are the same, the widths Wn2 and Wp2 of the lead connecting taps of the neighboring electrodes are equal to or more than half of the electrode widths Wn1 and Wp1 And may be formed so that predetermined regions overlap each other between the electrodes.
종래의 플렉서블 전지들은 전극 탭 및 전극 리드가 결합되는 탭-리드 결합부가 전극 조립체의 분리막 외부로 형성 및 외부로 노출되어 있어, 벤딩과 같은 플렉서블한 환경에서 내구성이 떨어져 전극리드가 분리되거나, 합제가 코팅되지 않은 전극 탭이 손상, 절단되는 현상이 잦았다.In the conventional flexible batteries, since the tab-and-lid coupling portion, to which the electrode tab and the electrode lead are coupled, is formed outside the separation membrane of the electrode assembly and exposed to the outside, durability is poor in a flexible environment such as bending and the electrode lead is separated, Uncoated electrode tabs were frequently damaged and severed.
이를 해결하기 위해, 본원 발명은 전극 탭과 전극 리드가 결합되는 탭-리드 결합부를 전극 조립체의 분리막 내부로 배치하여 그 현상을 보완하였다. 하지만, 여기서도 더 많은 횟수의 외부 힘이 반복적으로 작용되면 분리막 내부에서도 전극 탭이 손상 및 절단되는 문제가 발생한다. 이는 분리막 내부에 배치되는 전극 탭과 탭-리드 결합부, 서로 다른 크기로 적층되는 전극들 간의 두께 단차로 인하여, 굽힘 시 단차부를 따라 형성되는 재료의 변형에 의해 나타난 현상이었다. 따라서, 본원 발명은 전극 조립체 내에서 두께단차를 최소화함으로써, 상기의 문제를 해결하고자 다음과 같은 플렉서블 전지 제조 방법을 제안한다.In order to solve this problem, the present invention compensates the phenomenon by disposing the tab-lead coupling portion, in which the electrode tab and the electrode lead are coupled, into the separation membrane of the electrode assembly. However, if the external force is repeatedly applied a larger number of times, the electrode tab is damaged and broken even in the membrane. This was due to deformation of the material formed along the step at the time of bending due to the step difference in thickness between the electrode tabs and the tab-to-lead joints disposed inside the separator and the electrodes stacked at different sizes. Accordingly, the present invention proposes a flexible battery manufacturing method as described below in order to solve the above problems by minimizing the thickness step in the electrode assembly.
만약, 서로 다른 극성을 가지고, (+) 전극리드, (-) 전극리드와 각각 연결되는 각 전극의 전극 탭이 동일한 방향으로 같은 선상에 위치하도록 분리막 외부에 배치되어 있는 경우, 서로 다른 극성을 가지는 각 전극의 전극 탭이 전기적으로 연결되면 내부쇼트가 일어나 안전성에 문제가 생길 수 있다. 즉, 이러한 문제가 발생되지 않기 위하여, 서로 다른 극성을 가지는 각 전극의 전극 탭은 겹쳐지지 않도록 서로 반대방향으로 분리되거나 이격 배치로 형성되고, 이러한 각 전극의 전극 탭 간의 위치 관계에 따라 각 전극의 전극 탭의 폭이 형성된다.If the electrode tabs having different polarities, and the electrode tabs of the respective electrodes connected to the (+) electrode lead and the (-) electrode lead are disposed outside the separation membrane so as to be positioned on the same line in the same direction, When the electrode tabs of the respective electrodes are electrically connected to each other, internal short-circuiting may occur, which may cause a safety problem. That is, in order not to cause such a problem, the electrode taps of the respective electrodes having different polarities are separated in the opposite directions or spaced apart from each other so as not to overlap each other. According to the positional relationship between the electrode taps of the respective electrodes, The width of the electrode tab is formed.
하지만, 본원 발명은 전극 탭이 전극조립체의 분리막 내부에 위치하고 분리막 내부에서 전극 탭과 전극 리드가 결합된 탭-리드 결합부가 형성될 수 있으므로, 분리막에 의해 서로 다른 극성의 각 전극의 전극 탭이 절연될 수 있다. 즉, 본원 발명의 각 전극은 각 전극에 구성된 전극 탭의 폭에 대한 설계 자유도가 향상될 수 있다. 예를 들어, 도 13a와 같이 서로 다른 극성의 각 전극의 전극 폭이 각각 Wn1, Wp1라고 할 때 리드 연결용 탭의 폭 Wn2, Wp2는 각각 전극 폭(Wn1, Wp1)의 절반(빨간색선) 이상이 되도록 제작할 수 있다. 즉, 각 전극의 리드 연결용 탭의 폭 Wn2, Wp2은 시각적/물리적으로 일정 영역이 겹쳐있는 것처럼 보이더라도 각 전극의 리드 연결용 탭 및 탭-리드결합부가 분리막에 의해 분리되어 전자 절연될 수 있다. 따라서, 본원 발명은 각 전극의 리드 연결용 탭의 폭 Wn2, Wp2을 각 전극의 전극 폭(Wn1, Wp1)의 절반이상으로 형성함으로써 전극조립체 내에서의 두께단차에 의한 전극탭-리드 결합부에서의 크랙 및 단선을 예방할 수 있게 된다.However, according to the present invention, since the electrode tab is located inside the separator of the electrode assembly, and the tab-lead coupling portion in which the electrode tab and the electrode lead are combined is formed inside the separator, . That is, each electrode of the present invention can improve the degree of design freedom with respect to the width of the electrode tab formed in each electrode. For example, assuming that the electrode widths of the electrodes of different polarities are Wn1 and Wp1, respectively, as shown in Fig. 13A, the widths Wn2 and Wp2 of the lead connecting tabs are equal to or larger than half of the electrode widths Wn1 and Wp1 . That is, even if the widths Wn2 and Wp2 of the lead connecting tabs of each electrode appear visually / physically overlapped with each other, the lead connecting tabs and the tab-lid connecting portions of the respective electrodes can be separated and separated by the separating film . Therefore, in the present invention, the widths Wn2 and Wp2 of the lead connecting tabs of the respective electrodes are formed to be equal to or more than half of the electrode widths Wn1 and Wp1 of the respective electrodes, It is possible to prevent cracking and disconnection.
다른 예를 들어, 도 13b는 리드 연결용 탭의 폭(예를 들어, Wn2)과 전극 폭(예를 들어, Wn1)이 동일한 경우를 설명하기 위한 도면이다. 도 13b를 참조하면, 제 1 전극의 리드 연결용 탭의 폭(1301) 및 제 2 전극의 리드 연결용 탭의 폭(1302)이 각 전극의 전극 폭과 동일하게 형성시킬 수 있다. 이 경우, 도 13a의 실시예와 같이 탭-리드결합부와 전극 탭이 전극조립체의 분리막 내부에 배치될 수 있어서, 각 전극 간의 쇼트 우려를 해소할 수 있다.13B is a view for explaining a case where the width (for example, Wn2) of the lead connecting tab and the electrode width (for example, Wn1) are the same. Referring to FIG. 13B, the width 1301 of the lead connecting tab of the first electrode and the width 1302 of the lead connecting tab of the second electrode may be the same as the electrode width of each electrode. In this case, as in the embodiment of Fig. 13A, the tab-and-lid coupling portion and the electrode tab can be disposed inside the separation membrane of the electrode assembly, thereby preventing a short-circuit between the electrodes.
도 13c는 본 발명의 일 실시예에 따른 전극 탭-리드 결합부에서의 합제 미코팅으로 인한 두께 단차를 줄이는 방법을 설명하기 위한 도면이다.FIG. 13C is a view for explaining a method of reducing a thickness step due to uncoated coating in an electrode tab-and-lead joint according to an embodiment of the present invention.
도 13c를 참조하면, 전극 탭-리드 결합부에서 합제 미코팅으로 인한 두께 단차를 최대한 줄여 주기 위해 전극리드와 연결되는 전극 탭 영역(1303)에, 양극, 양극 및 전해액과 반응하지 않는 가요성의 물질(예를 들어 아크릴계, 우레탄계 등의 수지 및 이들을 혼합하여 구성한 필름, 테이프 또는 점착제 등을 삽입 또는 부착할 수 있다. 상기의 가요성의 물질은 전극조립체를 구성하는 전극 합제층 각각의 유연성과 유사하거나 더 좋은 것을 채택할 수 있다.Referring to FIG. 13C, in an electrode tab region 1303 connected to an electrode lead in order to minimize a thickness step due to uncoated coating in an electrode tab-lead coupling portion, a flexible material which does not react with the positive electrode, (For example, a resin such as acrylic or urethane, and a film, a tape, or a pressure-sensitive adhesive that is made by mixing these materials can be inserted or adhered). The flexible material described above has flexibility similar to or better than that of each of the electrode mixture layers constituting the electrode assembly Good things can be adopted.
도 14는 본 발명의 일 실시예에 따른 다수의 전극들을 적층함으로써 전지의 유연성을 향상시키기 위한 방법을 설명하기 위한 도면이다. 도 14를 참조하면, 본원 발명을 이용하여 다양한 전극 적층구조 및 적층수의 플렉서블 전지를 제조하여 전지의 유연성을 향상시킬 수 있다. 이 때, 전극 리드와 전극 탭을 연결함으로써 형성된 탭-리드 결합부는 전극 조립체의 분리막 내에 위치하도록 한다. 또한, 본원 발명은 각 전극의 전극 탭-리드 결합부 영역에서 형성되는 두께 단차를 효과적으로 줄임으로써 전지의 굽힘 특성이 요구되는 사용 환경에서 기존보다 더 향상된 유연성과 안정적인 구동이 가능함과 동시에, 내부 쇼트와 같은 위험으로부터 안전해질 수 있다. 또한, 본원 발명에서 상술한 바와 같이, 전극리드와 결합되는 전극 리드 연결용 탭의 폭을 종래의 플렉서블 전지와 비교하여 더 크게 설계할 수 있어 안정적인 전류흐름 경로를 확보함으로써 전지의 내부저항 상승을 최소화할 수 있고, 저항으로 인한 발열을 최소화함으로써 안전성을 확보할 수 있다.14 is a view for explaining a method for improving the flexibility of a battery by stacking a plurality of electrodes according to an embodiment of the present invention. Referring to FIG. 14, flexibility of a battery can be improved by manufacturing a flexible battery having various electrode stacking structures and stacked numbers by using the present invention. At this time, the tab-lead coupling portion formed by connecting the electrode lead and the electrode tab is located in the separation membrane of the electrode assembly. In addition, the present invention effectively reduces the thickness step formed in the region of the electrode tab-and-lead connection portion of each electrode, thereby enabling more flexible flexibility and stable driving in a use environment requiring bending characteristics of the battery, You can be safe from the same risks. In addition, as described in the present invention, the width of the tab for connecting the electrode leads to be connected to the electrode leads can be designed to be larger than that of the conventional flexible battery, thereby ensuring a stable current flow path, And safety can be ensured by minimizing the heat generated by the resistance.
도 15는 본 발명의 일 실시예에 따라 최외곽 전극이 양극인 경우와 음극인 경우로 구분하고, 여기에 전극리드 연결용 탭의 폭을 서로 상이하게 구성하여 조합한 전극 조립체들을 제작하였고, 제작한 각각의 전극 조립체로 구성된 전지의 벤딩 평가 결과를 나타낸 그래프이다.15 is a sectional view of an electrode assembly according to an embodiment of the present invention. The electrode assemblies are manufactured by dividing the outermost electrode into an anode and a cathode, FIG. 3 is a graph showing a result of bending evaluation of a battery composed of one electrode assembly. FIG.
여기서, 평가 시료는 총 4종류(최외곽 전극을 음극으로 배치+기존 전극 탭, 최외곽 전극을 음극으로 배치+개발 전극 탭, 최외곽 전극을 양극으로 배치+기존 전극 탭, 최외곽 전극을 양극으로 배치+개발 전극 탭)로 구성하였다. 개발 전극 탭이란, 상술한 바와 같이 전극조립체의 분리막 내부에 위치하며 분리막을 경계로 서로 대면하는 상이한 극성의 전극 사이에 각각 구성된 전극 리드연결용 탭부의 위치 관계에 있어서, 리드연결용 탭 영역이 투영영역 기준으로 서로 겹치도록 구성된 전극 탭을 의미한다.Here, the evaluation samples were classified into four types (the outermost electrodes were arranged as cathodes + the conventional electrode tabs and the outermost electrodes were arranged as cathodes + the developed electrode tabs, the outermost electrodes were arranged as anodes + the conventional electrode tabs, + Development electrode tab). As described above, in the positional relationship of the electrode lead connecting tabs, which are located inside the separating film of the electrode assembly and are formed between electrodes of different polarities facing each other with the separating film facing each other, as described above, Quot; means an electrode tab configured to overlap with each other on the basis of a region.
도 15를 참조하면, 충전상태 50%인 각 시료를 이용하여 반복굽힘 평가를 진행하면서 전압을 모니터링 하였다.Referring to FIG. 15, the voltage was monitored while repeated bending evaluation was performed using each sample having a 50% charged state.
시험 조건은 곡률반경 20mm, 굽힘속도 분당 25회로 하여 반복 벤딩을 진행하면서 실시간으로 전압을 확인한 결과이다. 이 결과로부터, 전극조립체의 최외곽 전극이 양극인 전지는 2,000회 반복굽힘 이전에 전압 노이즈가 발생하였고 전극리드연결용 탭 부분이 절단되면서 전압이 급격히 떨어졌다. 하지만, 전극조립체의 최외곽전극이 음극인 전지는 최외곽 전극이 양극인 전지보다 더 나은 내구성을 보였으며, 개발 전극 탭으로 구성된 전지의 경우, 기존 전극 탭보다 더 우수한 내구성을 나타냈다. 따라서, 본원 발명에 따라 전극조립체의 최외곽전극이 음극이고 개발 전극 탭 구조로 구성된 플렉서블 전지는, 종래의 플렉서블 전지보다 반복굽힘 등의 외력에 의한 내구성 면에서 우수하다고 볼 수 있다. The test conditions are the result of checking the voltage in real time while repeating bending with a curvature radius of 20 mm and a bending rate of 25 times per minute. As a result, the battery having the outermost electrode of the electrode assembly as an anode generated voltage noise before bending 2,000 times repeatedly, and the voltage dropped sharply as the tab portion for connecting the electrode lead was cut off. However, the cell with the outermost electrode of the electrode assembly has a better durability than the cell with the outermost electrode as the anode, and the battery composed of the developed electrode tab has better durability than the existing electrode tab. Therefore, according to the present invention, a flexible battery having a negative electrode and an outermost electrode of an electrode assembly and having a developed electrode tab structure is considered to be superior in durability due to external force such as repetitive bending, compared with a conventional flexible battery.

Claims (13)

  1. 분리막을 사이에 두고 상이한 극성을 갖는 한 쌍의 전극판을 갖는 하나 이상의 단위셀; 및At least one unit cell having a pair of electrode plates having different polarities with a separator interposed therebetween; And
    상기 전극판에 형성된 전극 탭;을 포함하고,And an electrode tab formed on the electrode plate,
    상기 전극 탭은 전극 병렬 연결용 탭과 전극 리드 연결용 탭을 포함하고,Wherein the electrode tab includes an electrode-parallel connection tab and an electrode lead connection tab,
    상기 전극판에는 상기 전극 병렬 연결용 탭과 전극 리드 연결용 탭 중 어느 하나 이상이 형성되며,Wherein at least one of the electrode-parallel connection tab and the electrode lead connection tab is formed on the electrode plate,
    최외곽 전극판은 음극이 배치되어 적층되는, 전극 조립체.Wherein the outermost electrode plate is stacked with a cathode disposed thereon.
  2. 제 1항에 있어서,The method according to claim 1,
    상기 최외곽 전극판에는 상기 전극 병렬 연결용 탭과 상기 전극 리드 연결용 탭이 형성되는, 전극 조립체.Wherein the outermost electrode plate is provided with the electrode-parallel connection tab and the electrode lead connection tab.
  3. 제 1항 또는 제 2항에 있어서,3. The method according to claim 1 or 2,
    전극 병렬 연결용 탭만을 포함한 상태에서 상이한 극성을 갖는 한 쌍의 전극판은,A pair of electrode plates having different polarities, including only the tabs for parallel connection of the electrodes,
    상기 한 쌍의 전극판 중 음극판 상에 도포된 음극합제의 면적은 양극판 상에 도포된 양극합제의 면적보다 크게 설정되며,The area of the negative electrode mixture applied on the negative electrode plate of the pair of electrode plates is set larger than the area of the positive electrode mixture applied on the positive electrode plate,
    상기 음극합제의 모서리는 상기 양극합제의 모서리를 기준으로 5㎜ 이내 범위에서 외측으로 벗어나도록 설정되고,The edge of the negative electrode mixture is set to deviate outward within a range of 5 mm or less based on the edge of the positive electrode mixture,
    단위면적 당 양극 용량에 대한, 단위면적 당 음극 용량은 1 내지 1.2 배의 범위인, 전극 조립체.Wherein the anode capacity per unit area with respect to the anode capacity per unit area is in the range of 1 to 1.2 times.
  4. 제 1항 또는 제 2항에 있어서,3. The method according to claim 1 or 2,
    상기 전극 병렬 연결용 탭만을 포함한 음극판과 상기 전극 병렬 연결용 탭과 상기 리드 연결용 탭을 모두 포함하는 양극판이 분리막을 사이에 두고 대면한 상태에서,Wherein the positive electrode plate including only the tab for electrode parallel connection and the positive electrode plate including both the electrode parallel connection tab and the lead connection tab face each other with the separator interposed therebetween,
    상기 전극 병렬 연결용 탭만을 포함한 음극판 상에 도포된 음극합제 면적이 상기 전극 병렬 연결용 탭과 상기 리드 연결용 탭을 모두 포함하는 양극판 상에 도포된 양극합제의 면적보다 크게 설정되며,The area of the negative electrode mixture applied on the negative electrode plate including only the electrode parallel connection tab is set larger than the area of the positive electrode mixture applied on the positive electrode plate including both the electrode parallel connection tab and the lead connection tab,
    상기 전극 병렬 연결용 탭만을 포함한 음극판의 모서리는 상기 양극합제의 모서리를 기준으로 5㎜ 이내 범위에서 외측으로 벗어나도록 설정되고,The edge of the negative electrode plate including only the tab for electrode parallel connection is set to deviate outward within a range of 5 mm or less with respect to the edge of the positive electrode mixture,
    상기 양극판에 형성된 탭-리드 결합부를 상기 전극 병렬 연결용 탭만을 포함한 음극판이 덮는 형태인, 전극 조립체.Wherein the tab-and-lid coupling portion formed on the positive electrode plate covers the negative electrode plate including only the electrode-parallel connection tab.
  5. 제 1항에 있어서,The method according to claim 1,
    상기 전극 조립체의 전극들 중 최상단 및 최하단에 배치된 최외곽 음극판은 전극 합제가 단면 도포된, 전극 조립체.And an outermost negative electrode plate disposed at the uppermost and lowermost ends of the electrodes of the electrode assembly is coated with an electrode mixture.
  6. 제 1항에 있어서,The method according to claim 1,
    상기 전극 조립체는,The electrode assembly includes:
    상기 전극 조립체를 구성하는 전극 탭 중 어느 하나의 전극 리드 연결용 탭 상에 형성된 보강 탭;을 더 포함하는, 전극 조립체.And a reinforcing tab formed on one of the electrode lead connecting tabs of the electrode tabs constituting the electrode assembly.
  7. 제 1항에 있어서,The method according to claim 1,
    상기 전극 조립체는,The electrode assembly includes:
    상기 전극 조립체를 구성하는 전극 탭 중 어느 하나의 전극 리드 연결용 탭 상에 결합된 전극 리드는 굽힘 구조를 더 포함하는, 전극 조립체.Wherein the electrode lead coupled to one of the electrode lead connecting tabs of the electrode tabs constituting the electrode assembly further comprises a bending structure.
  8. 제 6항에 있어서,The method according to claim 6,
    상기 전극 리드 연결용 탭과 전극 리드를 상기 보강 탭을 이용하여 덧대어진 구조의 탭-리드 결합부는 상기 분리막의 내측에 위치하는 상태인, 전극 조립체.Wherein the tab-lead coupling portion of the electrode lead connecting tab and the electrode lead padded with the reinforcing tab is located inside the separating film.
  9. 제 7항에 있어서,8. The method of claim 7,
    상기 전극 리드 연결용 탭과 굽힘 구조의 전극 리드가 결합된 탭-리드 결합부는 상기 분리막의 내측에 위치하는 상태인, 전극 조립체.Wherein the tab-lead coupling portion, in which the electrode lead connecting tab and the electrode lead of the bending structure are coupled, is located inside the separating membrane.
  10. 제 1항에 있어서,The method according to claim 1,
    상기 전극 조립체; 및The electrode assembly; And
    상기 전극 조립체를 감싸는 외장재;를 포함하고,And a casing covering the electrode assembly,
    상기 외장재부는 상기 전극 조립체의 외부를 둘러싸도록 상부 압인부와 하부 압인부가 반복 압인 가공된 구조인, 리튬이온 이차전지.Wherein the outer sheath portion has a structure in which the upper electrode portion and the lower electrode portion are formed in a repetitive manner so as to surround the outer surface of the electrode assembly.
  11. 제 10 항에 있어서,11. The method of claim 10,
    상기 복수의 상부 압인부와 하부 압인부는 상기 전극조립체 및 외장재부의 폭과 평행한 방향으로 형성되는, 리튬이온 이차전지.Wherein the plurality of upper depressions and lower depressions are formed in a direction parallel to a width of the electrode assembly and the outer casing.
  12. 제 1항에 있어서,The method according to claim 1,
    상기 전극 조립체는 서로 다른 면적의 전극을 3개 이상 적층하여 구성하는 것을 특징으로 하여 형성되는, 리튬이온 이차전지Wherein the electrode assembly is formed by stacking three or more electrodes having different areas. The lithium ion secondary battery
  13. 제 12항에 있어서,13. The method of claim 12,
    상기 전극 조립체를 구성하는 전극들 중, 상기 전극 병렬 연결용 탭과 상기 리드 연결용 탭을 포함하는 양극판의 면적이, 상기 전극 조립체를 구성하는 전극들 중 가장 작은 것인, 리튬이온 이차전지Wherein an area of the positive electrode plate including the electrode parallel connection tab and the lead connection tab among the electrodes constituting the electrode assembly is the smallest among the electrodes constituting the electrode assembly,
PCT/KR2018/014386 2017-11-21 2018-11-21 Electrode assembly having negative electrode disposed as outermost electrode, and lithium-ion secondary battery having same WO2019103467A1 (en)

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JP2020546260A JP2021503707A (en) 2017-11-21 2018-11-21 An electrode assembly in which the outermost electrode is arranged at a cathode and a lithium ion secondary battery having the electrode assembly.
CN201880075524.3A CN111386625A (en) 2017-11-21 2018-11-21 Electrode assembly having negative electrode disposed as outermost electrode and lithium ion secondary battery including the same
CN202410745961.9A CN118554136A (en) 2017-11-21 2018-11-21 Electrode assembly having negative electrode provided as outermost electrode and lithium ion secondary battery including the same
EP18880693.9A EP3716390A4 (en) 2017-11-21 2018-11-21 Electrode assembly having negative electrode disposed as outermost electrode, and lithium-ion secondary battery having same
US16/878,941 US11870103B2 (en) 2017-11-21 2020-05-20 Electrode assembly having negative electrode disposed as outermost electrode, and lithium-ion secondary battery having same
JP2023140736A JP2023158040A (en) 2017-11-21 2023-08-31 electrode assembly
US18/523,282 US20240106091A1 (en) 2017-11-21 2023-11-29 Electrode assembly having negative electrode disposed as outermost electrode, and lithium-ion secondary battery having same

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