WO2009048303A2 - Electrochemical cell - Google Patents

Electrochemical cell Download PDF

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Publication number
WO2009048303A2
WO2009048303A2 PCT/KR2008/005986 KR2008005986W WO2009048303A2 WO 2009048303 A2 WO2009048303 A2 WO 2009048303A2 KR 2008005986 W KR2008005986 W KR 2008005986W WO 2009048303 A2 WO2009048303 A2 WO 2009048303A2
Authority
WO
WIPO (PCT)
Prior art keywords
current collector
electrode assembly
terminal
electrochemical cell
electrode
Prior art date
Application number
PCT/KR2008/005986
Other languages
French (fr)
Other versions
WO2009048303A3 (en
Inventor
Seong Min Kim
Original Assignee
Kim's Techknowledge Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kim's Techknowledge Inc. filed Critical Kim's Techknowledge Inc.
Publication of WO2009048303A2 publication Critical patent/WO2009048303A2/en
Publication of WO2009048303A3 publication Critical patent/WO2009048303A3/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • 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
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/10—Multiple hybrid or EDL capacitors, e.g. arrays or modules
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/10—Multiple hybrid or EDL capacitors, e.g. arrays or modules
    • H01G11/12—Stacked hybrid or EDL capacitors
    • 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
    • H01M10/0404—Machines for assembling batteries
    • H01M10/0409—Machines for assembling batteries for cells with wound electrodes
    • 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
    • H01M10/0413—Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes
    • H01M10/0418—Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes with bipolar electrodes
    • 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
    • H01M10/0436—Small-sized flat cells or batteries for portable equipment
    • H01M10/044—Small-sized flat cells or batteries for portable equipment with bipolar electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/54—Connection of several leads or tabs of plate-like electrode stacks, e.g. electrode pole straps or bridges
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/562—Terminals characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/564—Terminals characterised by their manufacturing process
    • H01M50/566—Terminals characterised by their manufacturing process by welding, soldering or brazing
    • 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
    • H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
    • H01M50/609—Arrangements or processes for filling with liquid, e.g. electrolytes
    • H01M50/627—Filling ports
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/147—Lids or covers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/552—Terminals characterised by their shape
    • H01M50/559—Terminals adapted for cells having curved cross-section, e.g. round, elliptic or button cells
    • 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
    • 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
    • Y02E60/13—Energy storage using capacitors
    • 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 disclosure relates to an electrochemical cell, and in particular to, an electrochemical cell having an improved structure for connecting a current collector connection part of an electrode to a terminal to provide high connection strength between the current collector and the terminal, a low resistance of the connection part, and improved uniformity and reliability of the connection part.
  • electrochemical cells have a mono polar structure.
  • a mono polar electrochemical cell includes a positive electrode composed of a positive active material formed on a current collector and a negative electrode composed of a negative active material formed on another current collector. These electrodes are disposed with opposite polarity sides facing each other, and a separator is inserted between the electrodes to form a unit-cell structure.
  • FIG. 1 illustrates a mono polar electrochemical cell of the related art.
  • the electrochemical cell 10 of the related art includes a positive electrode 11, a negative electrode 12, a separator 13, an electrolyte 14, terminals 15-1 and 15-2, and a case 16.
  • the illustrated electrochemical cell is the minimum basic operation unit which is called a unit cell.
  • the separator 13 inserted between the positive and negative electrodes 11 and 12 is electrically nonconductive.
  • the separator 13 is formed of a material capable of transmitting the electrolyte 14, such as porous polymer, fiber glass mat, and paper.
  • the resistance of an electrochemical cell using liquid electrolyte is affected by factors such as the conductivity of the liquid electrolyte, the shape of assembled electrodes, and the connection structure between a terminal and an electrode. As the capacity of the electrochemical cell increases, the resistance of the electrochemical cell is more affected by the terminal-electrode connection structure.
  • one or more leads are attached to an electrode or a portion of the electrode is formed into a lead, and then the lead is connected to a terminal by a method such as crimping and welding.
  • an active material is not formed on a current collector extension part of an electrode.
  • an electrode assembly is assembled in a manner such that current collector extension parts of positive and negative electrodes are arranged to face opposite sides, and sides of a terminal and the electrode assembly are weld together by a laser.
  • current collectors of electrodes of most electrochemical cells are very thin, it is difficult to connect a terminal to a cut edge of a current collector, and thus the terminal is connected to a side of the current collector after bending the current collector by a method such as swaging.
  • the thickness of current collectors is small, and low-strength materials such as aluminum and copper are used to form current collectors.
  • connection part between a current collector and a terminal can be easily damaged by vibration and impact, and it is difficult to reduce the resistance of the connection part.
  • terminals are connected to current collectors by welding, resistance deviations and errors are caused because it is difficult to align the current collectors properly. Disclosure of Invention
  • the present disclosure provides an electrochemical cell in which strips are inserted between current collector extension parts of electrodes connected to a terminal to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part.
  • the present disclosure also provides an electrochemical cell in which edge portions of current collector extension parts of electrodes connected to a terminal have a larger thickness to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part.
  • an electrochemical cell including: positive and negative electrodes including current collectors, active material layers disposed on the current collectors, and current collector extension parts configured to be connected to a terminal; an electrode assembly, in which a strip is inserted between the current collector extension parts of at least one of the positive and negative electrodes, and the current collector extension parts of the positive and negative electrodes are arranged to face opposite sides; an electrolyte injection hole formed in the current collector extension part of the electrode; and a terminal connected to a side surface of the electrode assembly, wherein the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering.
  • an electrochemical cell including: an electrode including a current collector and an active material layer disposed on a part of the current collector, wherein an edge portion of an extension part of the current collector configured to be connected to a terminal is thicker than the part of the current collector on which the active material layer is disposed; an electrode assembly including at least the electrode as one polarity electrode and in which current collector extension parts of positive and negative electrodes are arranged to face opposite sides; and a terminal connected to a side surface of the electrode assembly, wherein the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering.
  • strips are inserted between current collector extension parts of electrodes connected to a terminal to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part.
  • edge portions of extension parts of current collectors connected to a terminal may be formed to have a larger thickness than the other portions of the current collectors to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part.
  • FIG. 1 illustrates a related- art electrochemical cell having a mono polar structure.
  • FIG. 2 is a perspective view illustrating an electrode of an electrochemical cell having a mono polar structure according to an exemplary embodiment.
  • FIG. 3 is a perspective view for illustrating a process of winding electrodes to form an electrode assembly.
  • FIG. 4 is a perspective view illustrating an electrode assembly formed by winding electrodes around a core.
  • FIG. 5 is an exploded perspective view for illustrating a process of accommodating an electrode assembly into a case.
  • FIG. 6 is a perspective view illustrating an electrochemical cell in which an electrode assembly is accommodated in a case.
  • FIG. 7 is a partial enlarged view of FIG. 6.
  • FIG. 8 is a sectional view for illustrating welding of an electrode assembly according to an exemplary embodiment.
  • FIGS. 9 and 10 are views for illustrating a contact method for an electrode assembly and a terminal according to an exemplary embodiment.
  • FIG. 11 is a perspective view illustrating an electrode including an integral strip current collector.
  • FIGS. 12 and 13 are views for illustrating a method of forming an electrolyte passage in the case of using a strip on a current collector of an electrode according to an exemplary embodiment.
  • FIGS. 14 and 15 are views for illustrating a method of forming an electrolyte passage in the case of using an integral strip current collector according to an exemplary embodiment.
  • FIG. 31 FIG.
  • FIG. 16 is a perspective view illustrating a stack type electrode assembly according to an exemplary embodiment.
  • FIG. 17 is a view illustrating arrangement of parts of an electrochemical cell having a four-series quasi-bipolar structure in which electrodes are wound around a core, according to an exemplary embodiment.
  • FIG. 18 is a view illustrating arrangement of parts of an electrochemical cell having a stack type two-series quasi-bipolar structure according to an exemplary embodiment.
  • FIG. 2 is a perspective view illustrating an electrode of an electrochemical cell having a mono polar structure according to an exemplary embodiment.
  • the electrode includes a current collector 210, active material layers 220 disposed on the current collector 210, and a current collector extension part on which no active material is disposed for being connected to a terminal.
  • the active material layers 220 store electric energy, and a current flows to the active material layers 220 through the current collector 210.
  • a positive electrode and a negative electrode are necessary, and although active materials used for forming active material layers of the positive and negative electrodes or materials for forming current collectors of the positive and negative electrodes may be different, the structures of the positive and negative electrodes are generally identical.
  • the current collector 210 has a sheet or foil shape.
  • a mesh type current collector can also be used.
  • the active material layer 220 is formed on at least one of the top and bottom surfaces of the current collector 210. In the case of the active material layers 220 are formed on both sides of the current collector 210, the active material layers 220 have the same polarity and overlap each other with the current collector 210 being disposed therebetween. That is, the widths and positions of the active material layers are qual.
  • FIG. 3 is a perspective view for illustrating a process of winding electrodes to form an electrode assembly.
  • a positive strip 230 is disposed on a current collector extension part of a positive electrode 230
  • a negative strip 250 is disposed on a current collector extension part of a negative electrode 260.
  • the current collector extension parts of the two electrodes 240 and 260 are arranged to face opposite sides, and the two electrodes 240 and 260 will be wound around a core 280 together with separators 270 disposed between the two electrodes 240 and 260.
  • the core shown in FIG. 3 may be omitted.
  • a strip may be formed of a metal. If a strip is formed of a metal, the strip may be formed of the same or the same kind of metal as that used for forming a current collector of an electrode on which the strip is to be disposed. Particularly, in the case where a terminal is connected to a current collector extension part of an electrode by welding, the terminal, a current collector of the electrode, and a strip disposed on the current collector extension part of the electrode may be formed of the same or the same kind of material. For example, if the current collector of the electrode is formed of aluminum, the terminal and the strip may be formed of aluminum or an aluminum alloy.
  • a side of the strip may be aligned with a side of the current collector extension part.
  • sides of strips and current collector extension parts of the electrodes can form a flat plane.
  • the thickness of strips may be set such that when electrodes are wound to form an electrode assembly, sides of the strips disposed on current collector extension parts of the electrodes make contact with current collector extension parts of neighboring electrodes as if the strips being inserted between the current collector extension parts. In this case, the current collector extension parts and the strips can be connected to terminals more stably.
  • grooves may be formed in the strips, and a strip aligning device such as a guide roller may be used.
  • a device such as a guide roller can also be used to align strips after attaching the strips to current collector extension parts of electrodes.
  • FIG. 4 is a perspective view illustrating an electrode assembly formed by winding electrodes around a core.
  • the electrode assembly shown in FIG. 4 is formed using metal strips. Sides of the strips are aligned with sides of current collector extension parts of electrodes, and the thickness of the strips are set such that sides of the strips make contact with current collector extension parts of neighboring electrodes. Therefore, sides of the electrode assembly are flat. In addition, the electrode assembly is assembled in a manner such that current collector extension parts of two electrodes having opposing polarities are disposed to face opposite sides.
  • FIG. 5 is an exploded perspective view for illustrating a process of accommodating an electrode assembly into a case.
  • Covers 310 used as terminals are coupled to both sides of a core of an electrode assembly 290, and the electrode assembly 290 is accommodated in the case 320.
  • Each of the covers 310 includes grooves 330.
  • the groove 330 makes contact with the current collector extension part and receives a laser beam so that a connection part between the terminal and the current collector extension part can be formed at the groove 330.
  • the cover 310 includes a core accommodation part 340 to receive the core.
  • FIG. 6 is a perspective view illustrating an electrochemical cell in which an electrode assembly is accommodated in a case.
  • FIG. 7 is a partial enlarged view of FIG. 6.
  • strips 153 are disposed on current collector extension parts of current collectors 112 of electrodes 110 located at both sides of the electrode assembly in a manner such that the strips 153 are wound overlapping each other between the current collector extension parts of the current collectors 112.
  • FIG. 7 shows a terminal welded on a side of the electrode assembly.
  • the strips 153, the current collector extension parts of the current collectors 112, and a groove 161 of a terminal are shown.
  • the terminal having the groove 161 is placed on the electrode assembly assembled as shown in FIG. 7, and a laser beam is cast through the groove 161 to weld the side of the electrode assembly and an inner surface of the groove 161. Then, as shown in FIG. 8, the groove 161 of the terminal, the current collector extension parts of the current collectors 112, and the strips 153 are weld together, and thus a strongly welded surface 170 is formed.
  • the welded surface 170 formed in this way may have a low electric resistance.
  • a flexible metal foil 181 etched like an etched aluminum foil can be inserted between grooves 161 of a terminal 160 and a side surface 182 of an electrode assembly 180.
  • the side surface 182 of the electrode assembly 180 formed by sides of the current collectors 112 and the strips 153 wound in the electrode assembly 180 is slightly uneven, a contact between the inner surfaces of the grooves 161 and the side surface 182 of the electrode assembly 180 can be uniformly maintained.
  • a metal film may be formed on the side surface 182 of the electrode assembly 180 by arc spraying or plasma spraying.
  • the terminal 160 may be electrically connected to the side surface 182 of the electrode assembly 180 by using a conductive adhesive.
  • a conductive adhesive For example, as shown in FIG. 10, after applying a conductive adhesive 183 to the side surface 182 of the electrode assembly 180 assembled as shown in FIG. 4, the terminal 160 can be attached to the electrode assembly 180. That is, the terminal 160 can be connected to the electrode assembly 180 using the conductive adhesive 183 without using a welding process.
  • the terminal 160 can be connected to the side surface of the electrode assembly 180 by soldering.
  • a soldering material may be applied to the side surface of the electrode assembly 180 instead of applying the conductive adhesive 183 shown in FIG. 10 to the side surface of the electrode assembly 180.
  • FIG. 11 is a perspective view illustrating an electrode including an integral strip current collector.
  • the electrode includes a current collector 360 on which active material layers 350 are formed.
  • An edge portion of a current collector extension part of the current collector 360 that will be connected to a terminal is thicker than the other portion of the current collector 360. In this way, a strip and an electrode can be formed in one piece for easy assembling of an electrode assembly.
  • longitudinal grooves may be formed in thicker edge portions of extension parts of the integral current collectors, and a strip aligning device such as a guide roller may be used.
  • FIG. 12 is a view for illustrating a method of forming an electrolyte passage in the case of using a strip on a current collector of an electrode according to an exemplary embodiment.
  • a strip 153 is disposed on an extension part 112-1 of the current collector 122 at a position apart from active material layers 111, and a plurality of electrolyte injection holes 113 are formed between the strip 153 disposed on the extension part 112-1 and the active material layers 111.
  • FIGS. 14 and 15 are views for illustrating a method of forming an electrolyte passage in the case of using an integral strip current collector according to an exemplary embodiment.
  • FIG. 6 An exemplary method of using an integral strip current collector is illustrated in FIG.
  • a plurality of electrolyte injection holes 113 are formed between active material layers 111 and an edge portion 114 of an extension part of a current collector 112.
  • Another method can be used to form an electrolyte injection passage.
  • electrolyte injection grooves 114-1 are formed at an edge portion 114 of an extension part of a current collector 112 to provide a passage between the inside and outside of an electrode assembly.
  • electrolyte injection holes are formed at a current collector extension part of an electrode as shown in FIGS. 12 and 14
  • additional electrolyte injection holes may be formed in a core of an electrode assembly at positions corresponding to the positions of the electrolyte injection holes formed at the current collector extension part of the electrode
  • an electrolyte injection port may be formed in a core accommodation part of a cover so as to inject electrolyte into the electrode assembly through the core.
  • a safety vent may be disposed at the electrolyte injection port of the cover.
  • electrolyte injection grooves are formed in an electrode instead of forming electrolyte injection holes in the electrode as shown in FIG. 15, electrolyte can be injected into an electrode assembly through a core as described above.
  • FIG. 16 is a perspective view illustrating a stack type electrode assembly according to an exemplary embodiment.
  • a strip 380 is disposed on a current collector extension part of an electrode 370 in which active material layers are disposed on both sides of a current collector; a separator is inserted between the electrode 370 and an electrode having a polarity opposite to that of the electrode 370; and the electrodes having opposite polarities are arranged in a manner such that the current collector extension parts of the electrodes face opposite directions. In this way, a plurality of electrodes each having the same polarity are arranged in the electrode assembly.
  • a terminal can be connected to a side surface of the electrode assembly assembled as shown in FIG. 16 in the same connection method as described above so as to increase the strength of the connection part between the terminal and the electrode assembly and decrease the electric resistance of the connection part.
  • the present invention can be applied to electrochemical cells having a quasi-bipolar structure as well as electrochemical cells having a mono polar structure.
  • FIG. 17 is a view illustrating arrangement of parts of an electrochemical cell having a four-series quasi-bipolar structure in which electrodes are wound around a core, according to an exemplary embodiment.
  • an electrode assembly is assembled by winding quasi-bipolar electrodes 390 and mono polar electrodes 420 around a core 430.
  • active material layers having a polarity are disposed on current collectors and are connected to terminals; the active material layers face an opposite polarity of the quasi-bipolar electrode 390; and strips 410 are disposed on extension parts of the current collectors.
  • the quasi-bipolar electrode 390 includes positive and negative active material layers disposed on a current collector and spaced apart from each other, and a polarity of the quasi-bipolar electrode 390 is used as an opposite polarity in a neighboring unit cell.
  • a terminal can be connected to a side surface of the electrode assembly in the same manner as described above to increase the strength of the connection part between the terminal and the electrode assembly and decrease the electric resistance of the connection part.
  • FIG. 18 is a view illustrating arrangement of parts of an electrochemical cell having a stack type two-series quasi-bipolar structure according to an exemplary embodiment.
  • an electrode assembly is assembled by stacking quasi-bipolar electrodes 510 and mono polar electrodes 530.
  • active material layers having a polarity are disposed on current collectors for being connected to a terminal; the active material layers face an opposite polarity of the quasi-bipolar electrode 510; and strips 520 are disposed on extension parts of the current collectors.
  • the quasi-bipolar electrode 510 includes positive and negative active material layers disposed on a current collector and spaced apart from each other, and a polarity of the quasi-bipolar electrode 510 is used as an opposite polarity in a neighboring unit cell.
  • a terminal can be connected to a side surface of the electrode assembly in the same manner as described above to increase the strength of the connection part between the terminal and the electrode assembly and decrease the electric resistance of the connection part.
  • electrochemical cells have been described according to exemplary embodiments.
  • the electrochemical cells can be applied to an ultracapacitor such as an electric double layer capacitor, and to other electric energy storage devices such as a lead acid battery, a NiMH battery, a NiCd battery, a lithium ion battery, and an aluminum electrolytic capacitor.
  • an ultracapacitor such as an electric double layer capacitor
  • other electric energy storage devices such as a lead acid battery, a NiMH battery, a NiCd battery, a lithium ion battery, and an aluminum electrolytic capacitor.

Abstract

Provided is an electrochemical cell having an improved structure to increase the connection strength between a terminal and current collectors, decrease the electric resistance of a connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part. The electrochemical cell includes: an electrode including a current collector and an active material layer disposed on a part of the current collector, wherein an edge portion of an extension part of the current collector configured to be connected to a terminal is thicker than the part of the current collector on which the active material layer is disposed; an electrode assembly including at least the electrode as one polarity electrode and in which current collector extension parts of positive and negative electrodes are arranged to face opposite sides; and a terminal connected to a side surface of the electrode assembly, wherein the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering.

Description

Description ELECTROCHEMICAL CELL
Technical Field
[1] The present disclosure relates to an electrochemical cell, and in particular to, an electrochemical cell having an improved structure for connecting a current collector connection part of an electrode to a terminal to provide high connection strength between the current collector and the terminal, a low resistance of the connection part, and improved uniformity and reliability of the connection part. Background Art
[2] Recently, the use of transportation means such as electric cars, hybrid electric cars, and trains, and high-power electric devices such as industrial power devices has been increased, and accordingly, electrochemical cells widely used as electric energy storage devices in such electric devices are increasingly required to be low in resistance. Therefore, many methods have been developed for reducing the resistance of electrochemical cells.
[3] In general, electrochemical cells have a mono polar structure. Such a mono polar electrochemical cell includes a positive electrode composed of a positive active material formed on a current collector and a negative electrode composed of a negative active material formed on another current collector. These electrodes are disposed with opposite polarity sides facing each other, and a separator is inserted between the electrodes to form a unit-cell structure.
[4] FIG. 1 illustrates a mono polar electrochemical cell of the related art.
[5] Referring to FIG. 1, the electrochemical cell 10 of the related art includes a positive electrode 11, a negative electrode 12, a separator 13, an electrolyte 14, terminals 15-1 and 15-2, and a case 16. The illustrated electrochemical cell is the minimum basic operation unit which is called a unit cell.
[6] Electric energy is stored in the positive electrode 11 and the negative electrode 12.
[7] The separator 13 inserted between the positive and negative electrodes 11 and 12 is electrically nonconductive.
[8] The separator 13 is formed of a material capable of transmitting the electrolyte 14, such as porous polymer, fiber glass mat, and paper.
[9] Particularly, the resistance of an electrochemical cell using liquid electrolyte is affected by factors such as the conductivity of the liquid electrolyte, the shape of assembled electrodes, and the connection structure between a terminal and an electrode. As the capacity of the electrochemical cell increases, the resistance of the electrochemical cell is more affected by the terminal-electrode connection structure. [10] In a common related- art method of connecting an electrode to a terminal, one or more leads are attached to an electrode or a portion of the electrode is formed into a lead, and then the lead is connected to a terminal by a method such as crimping and welding.
[11] However, this method makes it difficult to reduce electric resistance, complicates the manufacturing process, and results in a current collector loss. Thus, the method is used for a limited range of electrochemical cells that do not required to have a low resistance.
[12] In a recently proposed method, an active material is not formed on a current collector extension part of an electrode. In detail, an electrode assembly is assembled in a manner such that current collector extension parts of positive and negative electrodes are arranged to face opposite sides, and sides of a terminal and the electrode assembly are weld together by a laser. However, since current collectors of electrodes of most electrochemical cells are very thin, it is difficult to connect a terminal to a cut edge of a current collector, and thus the terminal is connected to a side of the current collector after bending the current collector by a method such as swaging. However, generally, the thickness of current collectors is small, and low-strength materials such as aluminum and copper are used to form current collectors. Thus, a connection part between a current collector and a terminal can be easily damaged by vibration and impact, and it is difficult to reduce the resistance of the connection part. Moreover, when terminals are connected to current collectors by welding, resistance deviations and errors are caused because it is difficult to align the current collectors properly. Disclosure of Invention
Technical Problem
[13] Accordingly, the present disclosure provides an electrochemical cell in which strips are inserted between current collector extension parts of electrodes connected to a terminal to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part.
[14] The present disclosure also provides an electrochemical cell in which edge portions of current collector extension parts of electrodes connected to a terminal have a larger thickness to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part. Technical Solution [15] According to an aspect, there is provided an electrochemical cell including: positive and negative electrodes including current collectors, active material layers disposed on the current collectors, and current collector extension parts configured to be connected to a terminal; an electrode assembly, in which a strip is inserted between the current collector extension parts of at least one of the positive and negative electrodes, and the current collector extension parts of the positive and negative electrodes are arranged to face opposite sides; an electrolyte injection hole formed in the current collector extension part of the electrode; and a terminal connected to a side surface of the electrode assembly, wherein the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering.
[16] According to another aspect, there is provided an electrochemical cell including: an electrode including a current collector and an active material layer disposed on a part of the current collector, wherein an edge portion of an extension part of the current collector configured to be connected to a terminal is thicker than the part of the current collector on which the active material layer is disposed; an electrode assembly including at least the electrode as one polarity electrode and in which current collector extension parts of positive and negative electrodes are arranged to face opposite sides; and a terminal connected to a side surface of the electrode assembly, wherein the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering.
Advantageous Effects
[17] In the electrochemical cell of the present disclosure, strips are inserted between current collector extension parts of electrodes connected to a terminal to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part.
[18] Alternatively, in the electrochemical cell, edge portions of extension parts of current collectors connected to a terminal may be formed to have a larger thickness than the other portions of the current collectors to increase the connection strength between the terminal and current collectors, decrease the electric resistance of the connection part between the terminal and the current collectors, and improve the uniformity and reliability of the connection part. Brief Description of the Drawings
[19] FIG. 1 illustrates a related- art electrochemical cell having a mono polar structure.
[20] FIG. 2 is a perspective view illustrating an electrode of an electrochemical cell having a mono polar structure according to an exemplary embodiment. [21] FIG. 3 is a perspective view for illustrating a process of winding electrodes to form an electrode assembly. [22] FIG. 4 is a perspective view illustrating an electrode assembly formed by winding electrodes around a core. [23] FIG. 5 is an exploded perspective view for illustrating a process of accommodating an electrode assembly into a case. [24] FIG. 6 is a perspective view illustrating an electrochemical cell in which an electrode assembly is accommodated in a case. [25] FIG. 7 is a partial enlarged view of FIG. 6.
[26] FIG. 8 is a sectional view for illustrating welding of an electrode assembly according to an exemplary embodiment. [27] FIGS. 9 and 10 are views for illustrating a contact method for an electrode assembly and a terminal according to an exemplary embodiment. [28] FIG. 11 is a perspective view illustrating an electrode including an integral strip current collector. [29] FIGS. 12 and 13 are views for illustrating a method of forming an electrolyte passage in the case of using a strip on a current collector of an electrode according to an exemplary embodiment. [30] FIGS. 14 and 15 are views for illustrating a method of forming an electrolyte passage in the case of using an integral strip current collector according to an exemplary embodiment. [31] FIG. 16 is a perspective view illustrating a stack type electrode assembly according to an exemplary embodiment. [32] FIG. 17 is a view illustrating arrangement of parts of an electrochemical cell having a four-series quasi-bipolar structure in which electrodes are wound around a core, according to an exemplary embodiment. [33] FIG. 18 is a view illustrating arrangement of parts of an electrochemical cell having a stack type two-series quasi-bipolar structure according to an exemplary embodiment.
Mode for the Invention [34] Hereinafter, specific embodiments will be described in detail with reference to the accompanying drawings. [35] FIG. 2 is a perspective view illustrating an electrode of an electrochemical cell having a mono polar structure according to an exemplary embodiment. [36] The electrode includes a current collector 210, active material layers 220 disposed on the current collector 210, and a current collector extension part on which no active material is disposed for being connected to a terminal. The active material layers 220 store electric energy, and a current flows to the active material layers 220 through the current collector 210. To constitute an electrochemical cell, a positive electrode and a negative electrode are necessary, and although active materials used for forming active material layers of the positive and negative electrodes or materials for forming current collectors of the positive and negative electrodes may be different, the structures of the positive and negative electrodes are generally identical.
[37] Generally, the current collector 210 has a sheet or foil shape. A mesh type current collector can also be used. The active material layer 220 is formed on at least one of the top and bottom surfaces of the current collector 210. In the case of the active material layers 220 are formed on both sides of the current collector 210, the active material layers 220 have the same polarity and overlap each other with the current collector 210 being disposed therebetween. That is, the widths and positions of the active material layers are qual.
[38] FIG. 3 is a perspective view for illustrating a process of winding electrodes to form an electrode assembly.
[39] As shown in FIG. 3, a positive strip 230 is disposed on a current collector extension part of a positive electrode 230, and a negative strip 250 is disposed on a current collector extension part of a negative electrode 260. The current collector extension parts of the two electrodes 240 and 260 are arranged to face opposite sides, and the two electrodes 240 and 260 will be wound around a core 280 together with separators 270 disposed between the two electrodes 240 and 260. Alternatively, the core shown in FIG. 3 may be omitted.
[40] Various materials can be used for forming a strip. For example, a strip may be formed of a metal. If a strip is formed of a metal, the strip may be formed of the same or the same kind of metal as that used for forming a current collector of an electrode on which the strip is to be disposed. Particularly, in the case where a terminal is connected to a current collector extension part of an electrode by welding, the terminal, a current collector of the electrode, and a strip disposed on the current collector extension part of the electrode may be formed of the same or the same kind of material. For example, if the current collector of the electrode is formed of aluminum, the terminal and the strip may be formed of aluminum or an aluminum alloy.
[41] When a strip is disposed on a current collector extension part of an electrode, a side of the strip may be aligned with a side of the current collector extension part. In this case, when an electrode assembly is formed by winding electrodes, sides of strips and current collector extension parts of the electrodes can form a flat plane. In addition, the thickness of strips may be set such that when electrodes are wound to form an electrode assembly, sides of the strips disposed on current collector extension parts of the electrodes make contact with current collector extension parts of neighboring electrodes as if the strips being inserted between the current collector extension parts. In this case, the current collector extension parts and the strips can be connected to terminals more stably.
[42] Furthermore, to precisely align strips with current collector extension parts of electrodes when an electrode assembly is fabricated, grooves may be formed in the strips, and a strip aligning device such as a guide roller may be used. Moreover, to easily fabricate an electrode assembly, a device such as a guide roller can also be used to align strips after attaching the strips to current collector extension parts of electrodes.
[43] FIG. 4 is a perspective view illustrating an electrode assembly formed by winding electrodes around a core.
[44] The electrode assembly shown in FIG. 4 is formed using metal strips. Sides of the strips are aligned with sides of current collector extension parts of electrodes, and the thickness of the strips are set such that sides of the strips make contact with current collector extension parts of neighboring electrodes. Therefore, sides of the electrode assembly are flat. In addition, the electrode assembly is assembled in a manner such that current collector extension parts of two electrodes having opposing polarities are disposed to face opposite sides.
[45] FIG. 5 is an exploded perspective view for illustrating a process of accommodating an electrode assembly into a case.
[46] Covers 310 used as terminals are coupled to both sides of a core of an electrode assembly 290, and the electrode assembly 290 is accommodated in the case 320. Each of the covers 310 includes grooves 330. When a terminal is connected to a current collector extension part of an electrode by laser welding, the groove 330 makes contact with the current collector extension part and receives a laser beam so that a connection part between the terminal and the current collector extension part can be formed at the groove 330. If the electrode assembly 290 is fabricated using a core, the cover 310 includes a core accommodation part 340 to receive the core.
[47] FIG. 6 is a perspective view illustrating an electrochemical cell in which an electrode assembly is accommodated in a case.
[48] FIG. 7 is a partial enlarged view of FIG. 6. Referring to FIG. 7, strips 153 are disposed on current collector extension parts of current collectors 112 of electrodes 110 located at both sides of the electrode assembly in a manner such that the strips 153 are wound overlapping each other between the current collector extension parts of the current collectors 112.
[49] In addition, FIG. 7 shows a terminal welded on a side of the electrode assembly. In detail, the strips 153, the current collector extension parts of the current collectors 112, and a groove 161 of a terminal are shown.
[50] The terminal having the groove 161 is placed on the electrode assembly assembled as shown in FIG. 7, and a laser beam is cast through the groove 161 to weld the side of the electrode assembly and an inner surface of the groove 161. Then, as shown in FIG. 8, the groove 161 of the terminal, the current collector extension parts of the current collectors 112, and the strips 153 are weld together, and thus a strongly welded surface 170 is formed. The welded surface 170 formed in this way may have a low electric resistance.
[51] In the case of using a laser welding method, a flexible metal foil 181 etched like an etched aluminum foil can be inserted between grooves 161 of a terminal 160 and a side surface 182 of an electrode assembly 180. In this case, although the side surface 182 of the electrode assembly 180 formed by sides of the current collectors 112 and the strips 153 wound in the electrode assembly 180 is slightly uneven, a contact between the inner surfaces of the grooves 161 and the side surface 182 of the electrode assembly 180 can be uniformly maintained. Alternatively, a metal film may be formed on the side surface 182 of the electrode assembly 180 by arc spraying or plasma spraying.
[52] Alternatively, the terminal 160 may be electrically connected to the side surface 182 of the electrode assembly 180 by using a conductive adhesive. For example, as shown in FIG. 10, after applying a conductive adhesive 183 to the side surface 182 of the electrode assembly 180 assembled as shown in FIG. 4, the terminal 160 can be attached to the electrode assembly 180. That is, the terminal 160 can be connected to the electrode assembly 180 using the conductive adhesive 183 without using a welding process.
[53] Alternatively, the terminal 160 can be connected to the side surface of the electrode assembly 180 by soldering. In this case, a soldering material may be applied to the side surface of the electrode assembly 180 instead of applying the conductive adhesive 183 shown in FIG. 10 to the side surface of the electrode assembly 180.
[54] Furthermore, other methods can be used instead of disposing strips on current collector extension parts of electrodes.
[55] FIG. 11 is a perspective view illustrating an electrode including an integral strip current collector. The electrode includes a current collector 360 on which active material layers 350 are formed. An edge portion of a current collector extension part of the current collector 360 that will be connected to a terminal is thicker than the other portion of the current collector 360. In this way, a strip and an electrode can be formed in one piece for easy assembling of an electrode assembly.
[56] To precisely align electrodes including integral strip current collectors when fabricating an electrode assembly using electrodes, longitudinal grooves may be formed in thicker edge portions of extension parts of the integral current collectors, and a strip aligning device such as a guide roller may be used.
[57] When an electrode assembly fabricated by disposing strips on current collector extension parts of electrodes or an electrode assembly fabricated using electrodes including integral strip current collectors as shown in FIG. 11 is used, it is necessary to inject electrolyte into the electrode assembly. Thus, a connection passage is necessary for connecting the inside of the electrode assembly in which active material layers and separators are disposed to the outside of the electrode assembly.
[58] FIG. 12 is a view for illustrating a method of forming an electrolyte passage in the case of using a strip on a current collector of an electrode according to an exemplary embodiment.
[59] As shown in FIG. 12, when a foil type current collector 112 is used in an electrode
110, a strip 153 is disposed on an extension part 112-1 of the current collector 122 at a position apart from active material layers 111, and a plurality of electrolyte injection holes 113 are formed between the strip 153 disposed on the extension part 112-1 and the active material layers 111.
[60] FIGS. 14 and 15 are views for illustrating a method of forming an electrolyte passage in the case of using an integral strip current collector according to an exemplary embodiment.
[61] An exemplary method of using an integral strip current collector is illustrated in FIG.
11.
[62] Referring to FIG. 14, in an electrode 110 including active material layers 111, a plurality of electrolyte injection holes 113 are formed between active material layers 111 and an edge portion 114 of an extension part of a current collector 112.
[63] Another method can be used to form an electrolyte injection passage.
[64] Referring to FIG. 15, in an electrode 110 including active material layers 111, electrolyte injection grooves 114-1 are formed at an edge portion 114 of an extension part of a current collector 112 to provide a passage between the inside and outside of an electrode assembly.
[65] Particularly, in the case where electrolyte injection holes are formed at a current collector extension part of an electrode as shown in FIGS. 12 and 14, additional electrolyte injection holes may be formed in a core of an electrode assembly at positions corresponding to the positions of the electrolyte injection holes formed at the current collector extension part of the electrode, and an electrolyte injection port may be formed in a core accommodation part of a cover so as to inject electrolyte into the electrode assembly through the core. Furthermore, a safety vent may be disposed at the electrolyte injection port of the cover.
[66] In the case where electrolyte injection grooves are formed in an electrode instead of forming electrolyte injection holes in the electrode as shown in FIG. 15, electrolyte can be injected into an electrode assembly through a core as described above.
[67] In the above descriptions, explanations are given on electrochemical cells including an electrode assembly composed of wound electrodes. However, the present invention can be applied to electrochemical cells including a stack type electrode assembly composed of stacked electrodes.
[68] FIG. 16 is a perspective view illustrating a stack type electrode assembly according to an exemplary embodiment.
[69] Referring to FIG. 16, in the electrode assembly, a strip 380 is disposed on a current collector extension part of an electrode 370 in which active material layers are disposed on both sides of a current collector; a separator is inserted between the electrode 370 and an electrode having a polarity opposite to that of the electrode 370; and the electrodes having opposite polarities are arranged in a manner such that the current collector extension parts of the electrodes face opposite directions. In this way, a plurality of electrodes each having the same polarity are arranged in the electrode assembly.
[70] A terminal can be connected to a side surface of the electrode assembly assembled as shown in FIG. 16 in the same connection method as described above so as to increase the strength of the connection part between the terminal and the electrode assembly and decrease the electric resistance of the connection part.
[71] The present invention can be applied to electrochemical cells having a quasi-bipolar structure as well as electrochemical cells having a mono polar structure.
[72] FIG. 17 is a view illustrating arrangement of parts of an electrochemical cell having a four-series quasi-bipolar structure in which electrodes are wound around a core, according to an exemplary embodiment.
[73] Referring to FIG. 17, an electrode assembly is assembled by winding quasi-bipolar electrodes 390 and mono polar electrodes 420 around a core 430. In two mono polar electrodes 420, active material layers having a polarity are disposed on current collectors and are connected to terminals; the active material layers face an opposite polarity of the quasi-bipolar electrode 390; and strips 410 are disposed on extension parts of the current collectors. The quasi-bipolar electrode 390 includes positive and negative active material layers disposed on a current collector and spaced apart from each other, and a polarity of the quasi-bipolar electrode 390 is used as an opposite polarity in a neighboring unit cell. A terminal can be connected to a side surface of the electrode assembly in the same manner as described above to increase the strength of the connection part between the terminal and the electrode assembly and decrease the electric resistance of the connection part.
[74] FIG. 18 is a view illustrating arrangement of parts of an electrochemical cell having a stack type two-series quasi-bipolar structure according to an exemplary embodiment.
[75] Referring to FIG. 18, an electrode assembly is assembled by stacking quasi-bipolar electrodes 510 and mono polar electrodes 530. In two mono polar electrodes 530, active material layers having a polarity are disposed on current collectors for being connected to a terminal; the active material layers face an opposite polarity of the quasi-bipolar electrode 510; and strips 520 are disposed on extension parts of the current collectors. The quasi-bipolar electrode 510 includes positive and negative active material layers disposed on a current collector and spaced apart from each other, and a polarity of the quasi-bipolar electrode 510 is used as an opposite polarity in a neighboring unit cell. A terminal can be connected to a side surface of the electrode assembly in the same manner as described above to increase the strength of the connection part between the terminal and the electrode assembly and decrease the electric resistance of the connection part.
[76] In the above, electrochemical cells have been described according to exemplary embodiments. The electrochemical cells can be applied to an ultracapacitor such as an electric double layer capacitor, and to other electric energy storage devices such as a lead acid battery, a NiMH battery, a NiCd battery, a lithium ion battery, and an aluminum electrolytic capacitor.
[77] While structures, operations, manufacturing methods have been particularly shown and described with reference to exemplary embodiments, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.
[78]

Claims

Claims
[1] An electrochemical cell comprising: positive and negative electrodes comprising current collectors, active material layers disposed on the current collectors, and current collector extension parts configured to be connected to a terminal; an electrode assembly, in which a strip is inserted between the current collector extension parts of at least one of the positive and negative electrodes, and the current collector extension parts of the positive and negative electrodes are arranged to face opposite sides; an electrolyte injection hole formed in the current collector extension part of the electrode; and a terminal connected to a side surface of the electrode assembly, wherein the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering.
[2] An electrochemical cell comprising: an electrode comprising a current collector and an active material layer disposed on a part of the current collector, wherein an edge portion of an extension part of the current collector configured to be connected to a terminal is thicker than the part of the current collector on which the active material layer is disposed; an electrode assembly comprising at least the electrode as one polarity electrode and in which current collector extension parts of positive and negative electrodes are arranged to face opposite sides; and a terminal connected to a side surface of the electrode assembly, wherein the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering.
[3] The electrochemical cell of claim 1 or 2, wherein the electrode assembly comprises an electrode comprising positive and negative active material layers disposed on a current collector and spaced apart from each other, and a polarity of the electrode is used as an opposite polarity in a neighboring cell.
[4] The electrochemical cell of claim 1 or 2, wherein the electrode assembly is formed by winding the electrodes.
[5] The electrochemical cell of claim 1 or 2, wherein the electrode assembly is formed by stacking the electrodes.
[6] The electrochemical cell of claim 1, wherein the strip is formed of the same kind of material as that used for forming the current collectors of the electrodes.
[7] The electrochemical cell of claim 2, wherein an electrolyte injection hole is formed in the extension part of the current collector of the electrode. [8] The electrochemical cell of claim 2, wherein a groove is formed in the edge portion of the extension part of the current collector and is connected to an outside of the electrode assembly. [9] The electrochemical cell of claim 1 or 7, wherein the electrode assembly is wound around a hollow core comprising an electrolyte injection hole formed at a position corresponding to the electrolyte injection hole formed in the current collector extension part, and an electrolyte injection port is disposed at a side of a case accommodating the electrode assembly and connected to an inside area of the core. [10] The electrochemical cell of claim 9, wherein a safety vent is disposed at the electrolyte injection port disposed at the side of the case. [11] The electrochemical cell of claim 1, wherein the electrode assembly is assembled such that ends of the current collector extension parts of the electrodes are flush with a side of the strip. [12] The electrochemical cell of claim 1, wherein if the terminal is connected to the side surface of the electrode assembly by welding, the terminal is connected to the current collector extension parts and the strip. [13] The electrochemical cell of claim 1 or 2, wherein if the terminal is connected to the side surface of the electrode assembly by welding, a thin flexible sheet formed of the same kind of material as that used for forming the current collector is inserted between the terminal and the side surface of the electrode assembly before the welding. [14] The electrochemical cell of claim 13, wherein the sheet is an etched aluminum foil. [15] The electrochemical cell of claim 1 or 2, wherein the terminal is connected to the side surface of the electrode assembly by laser welding. [16] The electrochemical cell of claim 1, wherein the electrode assembly is assembled such that both sides of the strip make contact with current collector extension parts of neighboring electrodes. [17] The electrochemical cell of claim 2, wherein the electrode assembly is assembled such that both sides of the edge portion of the extension part of the current collector make contact with current collector extension parts of neighboring electrodes. [18] An electrochemical cell comprising: positive and negative electrodes comprising current collectors, active material layers disposed on the current collectors, and current collector extension parts configured to be connected to a terminal; an electrode assembly, in which a strip is inserted between the current collector extension parts of at least one of the positive and negative electrodes, and the current collector extension parts of the positive and negative electrodes are arranged to face opposite sides; and a terminal connected to a side surface of the electrode assembly, wherein the strip comprises a groove in a length direction of the strip, and the terminal is connected to the side surface of the electrode assembly by using at least one of welding, a conductive adhesive, and soldering. [19] The electrochemical cell of claim 2, wherein a groove is formed in the edge portion of the extension part of the current collector in a length direction of the edge portion.
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