JP2009164164A - Process for fabricating electrode element and electrochemical device for storage equipped with electrode element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for fabricating an electrode element of a type of double-sided electrode which can reduce the contact resistance of a tab terminal without requiring an expensive facility for exclusive use. <P>SOLUTION: In a process for fabricating an electrode element having an element body 11 formed by coating the opposite sides of a current collector 12 consisting of a metal foil with predetermined electrode materials 13a and 13b, and a tab terminal 21 fixed to a predetermined part of the element body 11, the element body 11 is formed by coating the opposite sides of the current collector 12 substantially entirely with predetermined electrode materials 13a and 13b, a part (12a for fixing a terminal) of the electrode material 13a applied to one side of the element body 11 is stripped wider than the width of the tab terminal 21 in order to expose the surface of the current collector 12, and then the tab terminal 21 is fixed to the exposed surface of the current collector. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an electrode element and an electrochemical device for electricity storage provided with the electrode element, and more particularly to a technique for reducing the resistance of the electrode element and simplifying the manufacture.

  Speaking of the electric double layer capacitor, the electric double layer capacitor includes, for example, an electrode element including an element body formed by applying a polarizable electrode mainly composed of activated carbon to a current collector made of an etched aluminum foil. Is used.

  This type of electrode element includes a single-sided electrode type in which a polarizable electrode is applied to one side of a current collector, and a double-sided electrode type in which a polarizable electrode is applied to both sides of a current collector (for example, Patent Documents). 1, 2, 3).

  In both the single-sided electrode type and the double-sided electrode type, a tab terminal for electrode extraction is attached to the element body. As a conventional example, FIG. 3 shows a single-sided electrode type electrode element, and FIGS. 4A and 4B show a double-sided electrode type electrode element.

  In the case of the single-sided electrode type electrode element of FIG. 3, the polarizable electrode 2 is formed only on one surface of the current collector 1, so that the tab terminal 3 is attached to the other surface side of the current collector 1. Usually, a “caulking method” in which a cone-shaped caulking needle is pierced is employed for this terminal attachment.

  In the case of the double-sided electrode type element shown in FIG. 4, since the polarizable electrodes 2 and 2 are formed on both sides of the current collector 1, the tab terminal 3 is placed on the polarizable electrode 2 as shown in FIG. If it is attached to the current collector 1, the contact resistance is increased.

  Therefore, in many cases, as shown in FIG. 4B, the polarizable electrode 2 is peeled off from both surfaces of the portion to be terminald to expose the current collector 1, and the tab terminal 3 is exposed on the exposed surface of the current collector 1. I am trying to install.

JP-A-5-74657 (FIGS. 2 and 3) JP-A-9-55344 (FIG. 3) JP-A-10-294102 (FIG. 10)

  In the case of the single-side electrode type electrode element of FIG. 3, the contact resistance of the tab terminal 3 is low, but since the polarizable electrode 2 is provided only on one side of the current collector 1, the capacitance per unit area compared to the double-sided type. When compared to a double-sided capacitor of the same size, the capacitance is only about 70%.

  According to the double-sided electrode element of FIG. 4B, the tab terminal 3 is directly applied to the current collector 1 as in the single-sided type, so that the contact resistance is low and the tab terminal 3 is distributed on both sides of the current collector 1. Since the polar electrodes 2 and 2 are formed, a large capacitance can be obtained, but there are the following problems.

  The method of peeling the polarizable electrode 2 from both sides of the current collector 1 includes a method of peeling one side at a time and a method of peeling simultaneously from both sides. In the method of peeling one side at a time, a jig used for this is a simple tool such as a brush. Although it may be a thing, the peeled position may be shifted between the front side and the back side.

  On the other hand, according to the method of peeling from both sides at the same time, the peeled position is not likely to be shifted between the front side and the back side, but a dedicated jig (equipment) is required, and the introduction cost becomes a burden. Absent.

  Accordingly, an object of the present invention is to provide a method for manufacturing an electrode element that is a double-sided electrode type, has a low contact resistance of a tab terminal, and does not require expensive dedicated equipment.

  In order to solve the above-mentioned problem, the invention described in claim 1 has an element body formed by applying a predetermined electrode material on both surfaces of a current collector made of a metal foil, and a tab is provided at a predetermined portion of the element body. In the method of manufacturing an electrode element to which a terminal is attached, a predetermined electrode material is applied to almost the entire surface of both sides of the current collector to prepare the element body, and then applied to one side of the element body. A part of the electrode material is peeled off with a width larger than the width of the tab terminal to expose the surface of the current collector, and the tab terminal is attached to the exposed surface of the current collector.

  According to a second aspect of the present invention, in the first aspect, the electrode material is peeled off with a brush.

  The invention described in claim 3 is characterized in that, in claim 1, the electrode material is peeled off by laser irradiation.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, any one of the caulking method, the cold weld method, the ultrasonic welding method, the laser welding method, and the resistance welding method is used. Or a plurality of methods.

  According to the present invention, as a fifth aspect of the present invention, there is provided a power storage electricity provided with a power storage unit in which at least a pair of electrode elements manufactured according to the first to fourth aspects are wound or stacked in a spiral shape with a separator interposed therebetween. Chemical devices are also included.

  Peel off a part of the electrode material on one side of the electrode material formed on almost the entire surface of the current collector with a width larger than the width of the tab terminal to expose the surface of the current collector, and expose the current collector According to the first aspect of the present invention in which the tab terminal is attached to the surface, since the tab terminal is directly applied to the current collector, the contact resistance can be lowered.

  In addition, only a part of the electrode material on one side only needs to be peeled off, which can be reduced by one step compared to the method of peeling the electrode material from the current collector one by one, and when the electrode material is simultaneously peeled from both surfaces of the current collector. So expensive expensive equipment is not required.

  According to the invention described in claim 2 in which the electrode material is peeled off with a brush, the stripping jig is inexpensive, and accordingly, the manufacturing cost of the electrode element can be reduced.

  According to the invention of claim 3 in which the electrode material is peeled off by laser irradiation, the electrode material can be removed neatly by clarifying the outline of the peeled surface.

  According to the invention of claim 4, the tab terminal is attached by caulking method, cold weld method, ultrasonic welding method, laser welding method, resistance welding method or a plurality of methods. The reliability and quality of the connection of the tab terminal can be selected according to the specifications required for the electrochemical device for electricity storage to which the electrode element is applied.

  The electrochemical device for electricity storage according to claim 5 includes an electric double layer capacitor, a lithium secondary battery, an electrochemical capacitor, and the like.

  Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view showing an electrode element manufactured according to the present invention, and FIG. 2 is an enlarged sectional view showing a main part of the electrode element. The electrode element according to this embodiment is an electrode element for an electric double layer capacitor.

  Referring to FIGS. 1 and 2, an electrode element 10 according to this embodiment basically includes an element body 11 and a tab terminal 21 attached to the element body 11 as an arrangement, and an electric double layer (not shown). Used for capacitor anode foil and cathode foil.

  The element body 11 is a double-sided electrode type, and includes a current collector 12 made of, for example, an aluminum etching foil. Polarized electrodes 13a and 13b as electrode materials are formed on both sides of the current collector 12 by coating.

  The polarizable electrodes 13a and 13b are made of, for example, an electrode material obtained by kneading activated carbon, carbon and PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PVA (polyvinyl alcohol), CMC (carboxymethyl cellulose), or the like as a binder. May be formed.

  The tab terminal 21 includes a terminal body 22 and a CP wire (solder-plated copper-clad steel wire) 25 attached to the terminal body 22. In recent years, solder plating of CP wire has been changed from lead to lead-free.

  The terminal main body 22 is formed by using a round bar wire of aluminum as a base material, leaving a round bar portion 24 of a predetermined length, and forming one end side of the round bar wire as, for example, a flat portion 23 like a battledore by pressing. The CP wire 25 is attached to the other end portion of the round bar portion 24 by welding.

  In the electrode element 10, the polarizable electrodes 13 a and 13 b are applied to almost the entire surface of the current collector 12 to produce the element body 11, and then the polarizability applied to one surface of the element body 11. A part of the electrode 13 a (terminal attachment portion 12 a) is peeled off to expose the surface of the current collector 12, and the tab terminal 21 is attached to the exposed surface of the current collector 12. The polarizable electrode 13b formed on the other surface is left as it is.

  The flat portion 23 of the tab terminal 21 is attached to the current collector 12. Therefore, when the width of the flat portion 23 is W1, the width of the terminal attachment portion 12a of the current collector 12 is set to a width W2 (> W1) larger than that.

  The simplest method for peeling off the polarizable electrode 13a from the terminal attachment portion 12a is a method using a brush. The brush may be either a rotating brush or a sliding (sliding contact) brush. When the outline of the terminal attachment portion 12a is clarified and the polarizable electrode 13a is removed cleanly, a laser irradiation method may be employed.

  As a terminal attaching method for attaching the tab terminal 21 to the current collector 12, any of a caulking method, a cold weld method, an ultrasonic welding method, a laser welding method, and a resistance welding method can be adopted. In that case, for example, a caulking method and a laser welding method may be used in combination.

  Specifically, after piercing a conical caulking needle from above the flat part 23 so as to penetrate the current collector 12, the petal-like nail piece formed on the back side thereof is crushed by pressing, and the nail piece The part is laser welded.

  According to the present invention, since the tab terminal 21 is directly applied to the current collector 12, the contact resistance can be lowered. In addition, only a part of the electrode material on one side (polarizable electrode 13a) has to be peeled off, and the number of steps can be reduced compared to the method of peeling off the electrode material described in the above-described conventional example one by one from the current collector. There is no need for expensive dedicated equipment as in the case of peeling the material from both sides of the current collector at the same time.

  Example 1 and Comparative Examples 1 to 3 were carried out using the same current collector, electrode material (polarizable electrode), tab terminal and caulking method.

Example 1
As shown in FIGS. 1 and 2, only a part of the electrode material on one side of the double-sided electrode type element body is peeled off with a brush to form a terminal attachment portion, and a flat portion of the tab terminal is caulked on the terminal attachment portion. Attached.

Example 2
As shown in FIGS. 1 and 2, only a part of the electrode material on one side of the double-sided electrode type element body is peeled off by laser irradiation (regardless of the type of laser (YAG, CO ₂ etc.)) to form a terminal attachment portion. The flat portion of the tab terminal was attached to the terminal attachment portion by caulking.

<Comparative example 1>
As shown in FIG. 3, the flat part of the tab terminal was attached to the back side (current collector exposed surface side) of the single-sided electrode type element body by a caulking method.

<Comparative example 2>
As shown in FIG. 4A, the flat portion of the tab terminal was attached by caulking from above the electrode material without peeling off the electrode material of the double-sided electrode type element body.

<Comparative Example 3>
As shown in FIG. 4B, the electrode material was peeled off from both surfaces of the terminal attachment portion of the double-sided electrode type element body by a brush, and the flat portion of the tab terminal was attached by caulking.

<Comparative example 4>
As shown in FIG. 4B, the tab material is flattened by peeling the electrode material by laser irradiation (regardless of the type of laser (YAG, CO _2, etc.)) from both sides of the terminal attachment portion of the double-sided electrode type element body. The parts were attached by caulking.

  First, the contact resistance (mΩ) of the tab terminals in Examples 1 and 2 and Comparative Examples 1 to 4 was measured using an AC ohmmeter (1 kHz) by a four-terminal method.

  Next, each electrode element (electrode material is a polarizable electrode) terminald in Examples 1 and 2 and Comparative Examples 1 to 4 is cut into 13 mm × 205 mm, and each pair is swirled together with a cellulose separator having a thickness of 50 μm. It was wound into a shape and housed in a φ12.5 aluminum case, TEMABF4 / PC was injected as an electrolyte, vacuum impregnated, and sealed with a sealing rubber to produce an electric double layer capacitor. The initial capacity (F) and initial internal resistance (mΩ) of each example were measured. The measurement results are shown in Table 1 below.

  As can be seen, Examples 1 and 2 and Comparative Examples 1, 3 and 4 satisfy both the contact resistance and the initial capacity. In Comparative Example 2, since the polarizable electrode remains between the tab terminal and the current collector, the contact resistance is high and the initial internal resistance is also high.

  Regarding the capacity, since Comparative Example 1 is a single-sided electrode type, the capacity is small. In Examples 1 and 2 and Comparative Examples 1, 3, and 4, the capacity decreases in the order of the amount of the polarizable electrode peeled off for terminal attachment.

  Next, the possibility of pressure bonding of the tab terminal was observed according to Examples 3 to 5 and Comparative Examples 5 to 9 below.

Example 3
As shown in FIG. 1 and FIG. 2, a part of the electrode material on one side of the double-sided electrode type element body is peeled off with a brush to form a terminal attachment portion, and the flat portion of the tab terminal is applied to the terminal attachment portion by the cold weld method. Attached.

Example 4
As shown in FIGS. 1 and 2, only a part of the electrode material on one side of the double-sided electrode type element body is peeled off by laser irradiation (regardless of the type of laser (YAG, CO ₂ etc.)) to form a terminal attachment portion. The flat portion of the tab terminal was attached to the terminal attachment portion by the cold weld method.

Example 5
As shown in FIGS. 1 and 2, only a part of the electrode material on one side of the double-sided electrode type element body is visually removed with a cloth (or tissue paper) to make a terminal attachment portion. The flat part of the tab terminal was attached by the cold weld method.

<Comparative Example 5>
As shown in FIG. 3, the flat portion of the tab terminal was attached to the back side (current collector exposed surface side) of the single-sided electrode type device body by the cold weld method.

<Comparative Example 6>
As shown in FIG. 4 (a), the flat portion of the tab terminal was attached from above the electrode material by the cold weld method without removing the electrode material of the double-sided electrode type element body.

<Comparative Example 7>
As shown in FIG. 4B, the electrode material was peeled off from both surfaces of the terminal attachment portion of the double-sided electrode type element body by a brush, and the flat portion of the tab terminal was attached by the cold weld method.

<Comparative Example 8>
As shown in FIG. 4B, the tab material is flattened by peeling the electrode material by laser irradiation (regardless of the type of laser (YAG, CO _2, etc.)) from both sides of the terminal attachment portion of the double-sided electrode type element body. The parts were attached by the cold weld method.

<Comparative Example 9>
As shown in FIG. 4B, the electrode material is visually peeled off from both sides of the terminal attachment portion of the double-sided electrode type element body with a cloth (or tissue paper) to make a terminal attachment portion. The flat part of the tab terminal was attached by the cold weld method.

Table 2 shows whether or not the tab terminals of Examples 3 to 5 and Comparative Examples 5 to 9 can be crimped.

  In the case of Example 3 and Comparative Example 7, the terminal was not pressure-bonded unless the electrode was peeled off strongly with a brush until the surface of the current collector (aluminum foil) was scraped. Example 4 and Comparative Examples 5 and 8 were bonded without problems. In Example 5 and Comparative Examples 6 and 9, no pressure bonding was performed.

  The reason why the parts peeled off by the cloth and those that were weakly peeled off by the brush were not crimped was that the surface of the part to be crimped to the terminal by the cold weld method was visually clean, but carbon still remained in the pits created by etching Therefore, there are few contact surfaces with aluminum.

The disassembled perspective view which shows the electrode element manufactured by this invention. The expanded sectional view which shows the principal part of the said electrode element. A typical sectional view showing the 1st conventional example. (A) Schematic sectional view showing a second conventional example, (b) Schematic sectional view showing a third conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrode element 11 Element main body 12 Current collector 12a Terminal attachment part 13a, 13b Polarized electrode (electrode material)
21 Tab terminal 22 Terminal body 25 CP wire

Claims (5)

In the method of manufacturing an electrode element having an element body formed by applying a predetermined electrode material on both sides of a current collector made of metal foil, and having a tab terminal attached to a predetermined portion of the element body,
After a predetermined electrode material is applied to almost the entire surface of both sides of the current collector to produce the element body, a part of the electrode material applied on one side of the element body is set to the width of the tab terminal. A method for producing an electrode element, comprising: peeling off with a larger width to expose the surface of the current collector, and attaching the tab terminal to the exposed surface of the current collector.   The method for manufacturing an electrode element according to claim 1, wherein the electrode material is peeled off with a brush.   The electrode element manufacturing method according to claim 1, wherein the electrode material is peeled off by laser irradiation.   The tab terminal is attached by any one method or a plurality of methods of a caulking method, a cold weld method, an ultrasonic welding method, a laser welding method, and a resistance welding method. 2. A method for producing an electrode element according to item 1.   An electrochemical device for electrical storage comprising an electrical storage body comprising at least a pair of electrode elements produced according to claims 1 to 4 spirally wound or laminated with a separator interposed therebetween.

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