JP5466065B2 - Method for producing electrochemical element - Google Patents

Description

  The present invention relates to a method for producing an electrochemical element such as a nonaqueous electrolyte battery or an electric double layer capacitor.

  Electrochemical elements such as non-aqueous electrolyte batteries and electric double layer capacitors are used for clock function backup power supplies, semiconductor memory backup power supplies, standby power supplies for electronic devices such as microcomputers and IC memories, solar watch batteries, and motor drives. It is used as a power source. In recent years, the demand for increasing the size and capacity of electrochemical devices tends to be low due to the non-volatility of semiconductor memories and the reduction in power consumption of timepiece functional devices. Rather, there is a strong demand for mounting on a substrate by downsizing, thinning, and reflow soldering. For this reason, a small and thin approximately square-shaped electrochemical element has been proposed, but an approximately rectangular-shaped electrochemical element can be crimped and crimped unlike a round-shaped electrochemical element. There wasn't. Therefore, a counter electrode made of a positive electrode and a negative electrode, a separator, and an electrolyte are housed in a substantially rectangular container, and a sealing plate is placed thereon, and seam welding is performed using a resistance welding method. (For example, patent document 1).

JP 2004-356209 A

  When seam welding using the resistance welding method is performed for sealing a substantially rectangular electrochemical element, compared to other welding methods, the welding speed cannot be increased and maintenance of the welding roller of the resistance welding machine is troublesome. There was a problem that it took.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing an electrochemical device capable of simplifying equipment maintenance in the manufacturing process of the electrochemical device. It is in.

The invention according to claim 1 is a storage step of storing a first electrode, a second electrode, a separator separating the first electrode and the second electrode, and an electrolytic solution in a container; A metal ring formed on the edge of the container and a sealing plate for sealing the container are arranged via a bonding material formed on the metal ring, and one or more peripheral portions of the sealing plate A first welding step of welding the metal ring and the sealing plate by a laser welding method , and after the first welding step , by the metal ring and the laser welding method at the periphery of the sealing plate a portion that is not welded and a second welding step of welding, the possess by resistance welding method, the first welding process, the container and the sealing plate fixed by a fixing jig, the said sealing plate the electrochemical device and performing under pressure to the container It is a production method.
According to this manufacturing method, the maintenance of equipment can be greatly simplified. Further, there is no positional deviation between the sealing plate and the container, and stable production can be achieved. Further, since the welding can be performed in a short time by fixing the position by pressurization, the welding can be effectively performed.

According to a second aspect of the present invention, in the method for manufacturing an electrochemical element according to the first or second aspect, the sealing plate is substantially square, and the first welding step includes two opposite sides of the sealing plate. In the second welding step, two sides of the sealing plate that have not been welded are welded.
According to this manufacturing method, two opposing sides can be welded simultaneously.

According to a third aspect of the present invention, in the method for manufacturing an electrochemical element according to the third aspect, the resistance welding in the second welding step is parallel seam welding.
According to this manufacturing method, parallel seam welding can be performed effectively, and even if there is an electrolytic solution inside the container, it can be sealed stably.

  The method of manufacturing an electrochemical element proposed by the present invention is such that only a small part necessary for the final sealing of the electrolyte is performed on the resistance welder by performing most of the welding with a laser welding machine with low maintenance frequency. This can effectively reduce the maintenance time for resistance welding.

It is sectional drawing of an electric double layer capacitor. It is a top view explaining an electric double layer capacitor welding method. It is a top view explaining an electric double layer capacitor welding method.

(First embodiment)
Hereinafter, a first embodiment in which an electrochemical element of the present invention is embodied in an electric double layer capacitor will be described with reference to FIGS. 1 and 2.

  FIG. 1 shows a cross-sectional view of an electric double layer capacitor as a rectangular parallelepiped electrochemical element. In FIG. 1, the electric double layer capacitor has a concave container 101 opened upward, and a sealing plate 102 welded to the container 101 and sealing the opening. In the container 101 sealed by the sealing plate 102, elements including a positive electrode active material 106 as a first electrode active material, a separator 105, a negative electrode active material 107 as a second electrode active material, and the like are disposed. It has become so. The square-shaped electrochemical element is effective in reducing the space occupancy in surface mounting.

  The concave container 101 was made of alumina, tungsten-printed on a green sheet, and a metal ring 109 made of Kovar (Co: 17, Ni: 29, Fe: remaining ratio alloy) was fired. Further, the connection terminal A 103 and the connection terminal B 104 were subjected to nickel and gold plating, and the upper portion of the metal ring 109 was subjected to nickel and gold plating serving as a bonding material 1081 (brazing material). The metal ring 109 was electrically connected to the connection terminal B104 by a tungsten layer passing through the left side of FIG.

  The connection terminals A and B reach the lower surface of the concave container. However, even if the connection terminals A and B are stopped at the side surface of the container, the connection terminals A and B can be soldered to the substrate by being wet with the solder.

  Tungsten used for wiring as a current collector and a metal layer were provided on the entire inner bottom surface of the concave container, and penetrated through the concave container wall surface and electrically connected to the connection terminal A103. The current collector and the positive electrode active material 106 were bonded with a conductive adhesive 1111 containing carbon.

The portion of the sealing plate 102 on the container side was subjected to nickel plating to be a bonding material 1082 (brazing material).
The electrolytic solution was put in the concave container 101 and covered. A cross-sectional view at that time is as shown in FIG.

  Next, the sealing plate 102 was pressed by a metal-made square pole-shaped fixing jig 301. FIG. 2A shows the state of the electrochemical cell viewed from above. With the sealing plate 102 pressed, the vicinity of the end portion of the sealing plate 102 visible from above was welded by a laser welding machine. FIG. 2B shows a state seen from the upper part after the fixing jig 301 is removed. In the vicinity of the end portion of the sealing plate 102, there is a continuous laser welded portion 302 and a portion 303 that is not welded.

  Furthermore, the sealing of the electrochemical cell was completed by welding the unwelded portion 303 in a seam shape with a resistance welder.

If the sealing plate 102 is temporarily fixed to the concave container 101 by spot welding or the like without using the fixing jig 301, then the entire periphery is welded by laser welding to complete the sealing. since you ejection gasified, welding failure occurs.

(Second Embodiment)
As for the configuration of the electrochemical cell, as in the first embodiment, the fixing jig 301 was changed to produce an electrochemical cell.
The sealing plate 102 was pressed with a fixing jig 304 made of a metal, a square pole and having both sides narrower than the center. The state of the electrochemical cell at this time as seen from above is shown in FIG. With the sealing plate 102 pressed, the vicinity of the end portion of the sealing plate 102 visible from above was welded by a laser welding machine. FIG. 3D shows a state seen from the top after the fixing jig 304 is removed. There are two continuous laser welds 302 and two unwelded locations 303 around the end of the sealing plate 102.

  Next, the non-welded portion 303 was welded in a seam shape by a parallel seam welding machine using the principle of resistance welding, thereby completing the sealing of the electrochemical cell. Thereby, even if there existed electrolyte solution inside, it was able to seal stably.

  In general, a roller-shaped head facing each other is often used as a welded portion of a parallel seam welding machine using the principle of resistance welding. The head is heated each time during resistance welding, and molten metal adheres to it, or wear is likely to occur due to pressurization during welding. Therefore, regular maintenance such as replacement and polishing is required. Also, compared to laser welding, the welding time is longer and it is difficult to increase production efficiency. According to the present invention, most of the welding can be performed by a laser welding machine having a low maintenance frequency. Only a small part necessary for the final sealing of the electrolyte can be performed on the resistance welder. Therefore, production efficiency can be greatly improved.

  The concave container 101 is preferably a heat resistant material such as a heat resistant resin, glass, ceramics or ceramic glass. As a manufacturing method, it is also possible to wire by low-melting glass or glass ceramics by conductor printing, and to laminate and fire at a low temperature. It is also possible to laminate by alumina printing and conductor printing and to fire.

The metal ring 109 is preferably made of a material having a thermal expansion coefficient close to that of the concave container 101.
For example, when the concave container 101 uses alumina having a thermal expansion coefficient of 6.8 × 10 −6 / ° C., it is desirable to use Kovar having a thermal expansion coefficient of 5.2 × 10 −6 / ° C. as the metal ring.

  Further, it is desirable to use the same Kovar as the metal ring in order to increase the reliability after welding for the sealing plate 102. This is because after the welding, when it is surface-mounted on the substrate of the equipment, that is, when reflow soldering, it is heated again.

  Further, the portion of the wiring that becomes the current collector is preferably tungsten, palladium, silver, platinum, or gold, which has good corrosion resistance and can be formed by a thick film method. Aluminum and carbon can also be used. In the case where the wiring on the bottom surface of the concave container 101 is used as the current collector on the positive electrode side, gold or tungsten is particularly preferable. This is because a material having a high withstand voltage is used so that it does not dissolve when a positive potential is applied.

  Furthermore, in order to improve the electrical connection between the electrode and the wiring, it is effective to use a conductive adhesive containing carbon. When a material having a low withstand voltage is used, it is effective to apply a conductive adhesive containing carbon to the metal of the current collector on the entire surface and bake and cure it. When aluminum is used, dry film formation such as vapor deposition or sputtering can be used.

  The connection terminals A103 and B104 are preferably provided with nickel, gold, tin, and solder layers for soldering to the base. It is preferable to provide a layer of nickel, gold, or the like that is compatible with the bonding material at the edge of the concave container 101. Examples of the layer forming method include vapor phase methods such as plating and vapor deposition.

  It is effective to provide a layer of nickel and / or gold as a brazing material on the surfaces where the metal ring 109 and the sealing plate 102 are joined. This is because the melting point of gold is 1063 ° C. and the melting point of nickel is 1453 ° C., but the melting point can be lowered to 1000 ° C. or less by using an alloy of gold and nickel. Examples of the layer forming method include a vapor phase method such as plating and vapor deposition, and a thick film method using printing. In particular, a thick film method using plating and printing is advantageous in terms of cost.

  However, impurity elements such as P, B, S, N, and C in the brazing material layer need to be 10% or less. Care must be taken especially when plating is used. For example, in electroless plating, P (phosphorus) tends to enter from the reducing agent sodium hypophosphite, and B (boron) easily enters from dimethylamine borane. Also, in electroplating, care must be taken because it may enter from brightener additives and anions. It is necessary to adjust the amount of reducing agent, additive, etc. to 10% or less. If it enters 10% or more, an intermetallic compound is formed on the joint surface and cracks are generated.

  When nickel is used for the bonding material 1082 on the sealing plate 102 side, gold is preferably used for the bonding material 1082 on the concave container 101 side. The ratio of gold to nickel is preferably between 1: 2 and 1: 1, and the melting point of the alloy is lowered, so that the welding temperature is lowered and the bondability is improved.

  Laser welding may be pulsed seam welding or continuous irradiation. In the seam welding by pulse, the laser is irradiated in a pulse shape, so that it becomes a seam shape after welding. If the pulse width is not controlled so that individual weld marks by the pulses overlap, complete sealing cannot be achieved.

  In the seam welding using the resistance welding method, welding is performed according to the principle of resistance welding by pressing a roller-type electrode facing two opposite sides of the sealing plate 102 and passing an electric current. Since the current flows in a pulsed manner while rotating the roller electrode, it becomes a seam shape after welding. If the pulse width is not controlled so that individual weld marks by the pulses overlap, complete sealing cannot be achieved.

  The separator to be used is preferably a heat-resistant nonwoven fabric. For example, a roll-rolled separator such as a porous film has heat resistance but shrinks in the rolling direction due to heat during seam welding using a resistance welding method. As a result, internal short circuit is likely to occur. In the case of a separator using a heat-resistant resin or glass fiber, shrinkage was good with little shrinkage. As the resin, PPS (polyphenylene sulfide) and PEEK (polyether ether ketone) were good. In particular, glass fiber was effective. A ceramic porous body can also be used.

The shape of the electrochemical element of the present invention is basically free, but the square shape is advantageous in efficiently arranging on the substrate because there is no protrusion such as a terminal.
Moreover, although the electrochemical element of the present invention has been described by taking an electric double layer capacitor as an example, it can also be applied to a non-aqueous electrolyte secondary battery or the like.

101 Concave Container 102 Sealing Plate 103 Connection Terminal A
104 Connection terminal B
105 Separator 106 Positive Electrode Active Material 107 Negative Electrode Active Material 1081 Bonding Material 1082 Bonding Material 109 Metal Ring 1111 Conductive Adhesive 1112 Conductive Adhesive 301 Fixing Jig 302 Laser Welding Portion 303 Unwelded Location 304 Fixing Jig

Claims (3)

A storage step of storing a first electrode, a second electrode, a separator separating the first electrode and the second electrode, and an electrolytic solution in a container;
A metal ring formed on the edge of the container and a sealing plate for sealing the container are arranged via a bonding material formed on the metal ring, and one or more peripheral portions of the sealing plate A first welding step of welding the metal ring and the sealing plate by a laser welding method,
After the first welding step, a second welding step of welding a portion not welded by the laser welding method with the metal ring at the peripheral portion of the sealing plate,
I have a,
The first welding step is performed by fixing the sealing plate and the container with a fixing jig and pressurizing the sealing plate against the container . The sealing plate is substantially rectangular,
In the first welding step, two opposing sides of the sealing plate are welded,
2. The method of manufacturing an electrochemical element according to claim 1 , wherein the second welding step welds two sides of the sealing plate that are not yet welded. The method for producing an electrochemical element according to claim 2 , wherein the resistance welding in the second welding step is parallel seam welding.

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