KR101030406B1 - Electrochemical cell - Google Patents

Abstract

In view of the liquid electrolyte contained therein, in order to avoid the problem of conventional nonaqueous electrolyte cells or electric double layer capacitors in the form of rectangular parallel pipes, which cannot achieve high reliability sealing unless the junction has a certain degree of sufficient margin, the nonaqueous electrolyte A metal layer with a coefficient of thermal expansion similar to the convex container of a battery or electric double layer capacitor and a metal layer comprising a brazing material is placed on the edge of the container and is made of a metal having similar properties to the metal ring and having a brazing layer on the joint surface. The plate is also used as a sealing plate, and a positive electrode and a negative electrode, a separator and an electrolyte are included in the convex container, the sealing plate is placed in a container, and seam welding is performed using parallel seam resistance welding to ensure high reliability sealing. Can be achieved.

Description

Electrochemical Battery {ELECTROCHEMICAL CELL}

1 is a cross-sectional view of a nonaqueous electrolyte cell or electric double layer capacitor of the present invention.

2 is a cross-sectional view of a conventional nonaqueous electrolyte cell or electric double layer capacitor.

3 is a cross-sectional view when the thickness of the metal layer is larger than the total thickness of the negative electrode active material 107 and the separator 105.

4 is a cross-sectional view of a nonaqueous electrolyte cell or an electric double layer capacitor when a step is provided in the convex container 101 of the present invention.

5 is a cross-sectional view of a nonaqueous electrolyte battery or an electric double layer capacitor when a step is provided inside the convex container 101 of the present invention.

<Description of the symbols for the main parts of the drawings>

101: convex container 102: sealing plate

103: connection terminal A 104: connection terminal B

105: separator 106: positive electrode active material

107: negative electrode active material 109: metal ring

1101: step 1111, 1112: carbon-containing conductive adhesive

The present invention relates to an electrochemical cell such as a surface mountable nonaqueous electrolyte battery and an electric double layer capacitor using the principle of an electric double layer.

Electrochemical cells, such as nonaqueous electrolyte batteries and electric double layer capacitors, include a backup power supply for a clock function, a backup power supply for a semiconductor memory, a backup power supply for an electronic device such as a microcomputer or an IC memory, a solar clock battery and a motor driving power supply, and the like. It has been used until now, and recently, it is considered as an auxiliary power storage unit of an electric vehicle power supply or an energy conversion / storage system.

BACKGROUND OF THE INVENTION In electrochemical cells such as nonaqueous electrolyte batteries and electric double layer capacitors, the demand for large capacity and current is reduced due to the advancement of nonvolatile semiconductor memories and the reduction of power consumption of visual functional devices. Thinning or reflow soldering (soldering cream or the like is applied to the part where soldering is applied on the printed board in advance and the parts are applied to the parts, or after the parts are applied, small solder balls (soldering) Bump) is supplied to the soldered portion, and the soldered portion is melted by passing the printed circuit board mounted with the component in a furnace of a high-temperature atmosphere set such that the soldered portion is higher than the melting point of the solder, for example, 200 to 260 ° C. There is an increasing demand for a nonaqueous electrolyte cell and an electric double layer capacitor.

2 shows a conventional electrochemical cell. The positive electrode of the positive electrode active material 201 and the electrode current collector 202, and the negative electrode of the negative electrode active material 204 and the electrode current collector 202 are separated by the separator 208 and the positive electrode case 203. And the electrolyte 206 by the negative electrode case 205. The positive case 203 and the negative case 205 are caulked and sealed by the gasket 207. In the conventional electrochemical cell, since it has a circular cross section such as a coin or a button, it is necessary to weld a terminal or the like to the casing in advance in order to perform reflow soldering, and it is cost in that the number of parts and the number of manufacturing processes are increased. The rise was going. Moreover, it is necessary to provide the terminal space on the board | substrate, and there was a limit in miniaturization.

Square electrochemical cells have also been examined, but it is difficult to take the sealing space with miniaturization.

[Patent Document 1] Japanese Patent Laid-Open No. 2001-216952

It is not possible to seal a square electrochemical cell by crimping a case different from the prototype cell. Therefore, the sealing plate must be joined to the top of the convex container and sealed by some or other means. Bonding methods include methods such as adhesives, hot press bonding, laser welding, ultrasonic welding, and resistance welding.

However, since the nonaqueous electrolyte cell or the electric double layer capacitor includes an electrolyte (generally a solution) inside, high reliability sealing cannot be achieved unless a margin is provided to the junction.

For example, a brazing material, such as a brazing material or brazing material, of approximately the same shape as the edge of the convex container is placed at its edges and clamped equally using a sealing plate, and at a temperature higher than the melting point of the brazing material or brazing material to apply the sealing. In the case of heating and compressing the sealing plate, if there is not enough margin in the joint, sufficient sealing cannot be obtained because the liquid electrolyte solution existing inside is heated and leaks to the outside.

In order to solve the above object, a metal layer is placed on the edge of the convex container of the electrochemical cell and the convex container and the sealing plate are joined by the metal layer to improve the sealing property. A positive electrode and a negative electrode, a separator and an electrolyte are included in the convex container, a sealing plate is placed thereon, and seam welding, in particular parallel seam resistance welding, is applied using a welding method. Since the sealing plate has a coefficient of thermal expansion similar to that of the convex container, high reliability sealing can be achieved.

The metal layer includes a metal ring and a brazing material, the metal ring has a coefficient of thermal expansion similar to that of the convex container, and the convex container and the sealing plate are joined by welding. In another embodiment, the metal layer is formed of a brazing material by plating, printing or cladding.

The convex container is preferably made of an insulator. More preferably, the convex container is made of ceramic or ceramic glass. In addition, the metal ring preferably comprises an alloy containing cobalt, nickel and iron, and the brazing material is preferably nickel and / or gold foil formed on the metal ring by plating, printing, or cladding.

The sealing plate includes a metal on which a brazing material is formed on the surface of the side joined with the convex container. The sealing plate has a coefficient of thermal expansion similar to that of the convex container. More preferably, the metal of the sealing plate contains an alloy containing cobalt, nickel and iron, and the brazing material formed on the surface of the side joined with the convex container is nickel and / or gold foil. The brazing material is formed by plating, printing, or cladding. The thickness of the metal ring located at the edge of the convex container is preferably smaller than the total thickness of the electrode and separator located at the side of the sealing plate.

A single step or multiple steps are formed inside the vessel, with the separator positioned at the step.

The electrode current collector is placed on the bottom inside the convex container. The electrode current collector comprises a metal mainly composed of a material selected from tungsten, aluminum, titanium, carbon, palladium, silver, platinum and gold. More preferably, a conductive layer composed mainly of carbon is placed in the electrode current collector.

In addition, the separator is made of polyphenylene sulfide, polyetheretherketone or glass fiber as a main component.

A representative structure of the present invention will be described with reference to FIG. 1. In the nonaqueous electrolyte cell or the electric double layer capacitor of the present invention, it is effective to manufacture a rectangular parallel pipe shape for reducing the mounting rate of the surface mounting space.

1 is a cross-sectional view of a nonaqueous electrolyte cell or electric double layer capacitor of the present invention in a rectangular parallel pipe shape. The convex container 101 is made of alumina, tungsten printed on a green sheet, and fired with a metal ring 109 made of cobalt (Co: 17, Ni: 29, Fe: alloy consisting of the rest). . Nickel / gold plating is applied to the connection terminal A 103 and the connection terminal B 104, and nickel and gold plating are applied to the metal ring 109 as a brazing material 1081 (soldering material). The convex container 101 and the metal ring 109 are preferably Ag-soldered, Ni-soldered, or Al-soldered. In addition, the thickness of the metal layer (metal ring 109 and brazing material 108) placed on the edge of the convex container 101 is smaller than the total thickness of the negative electrode active material 107 and the separator 105. When the thickness of the metal layer is larger than the total thickness of the negative electrode active material 107 and the separator 105, the metal layer and the positive electrode active material 106 may contact each other, thereby degrading the function as a nonaqueous electrolyte battery or an electric double layer capacitor. 3 is a cross-sectional view when the thickness of the metal layer is larger than the total thickness of the negative electrode active material 107 and the separator 105. When the position of the positive electrode active material 106 is moved by scattering in the manufacturing stage, it may come into contact with the metal ring 109 and cause an internal short circuit.

The metal ring 109 is electrically connected to the connection terminal B 104 by a tungsten layer passing through the left side of FIG. 1.

Even when the connecting terminals A and B reach the outer bottom of the convex container and are held on the side of the container, they can be soldered to the substrate by soldering by wetting.

A metal layer of tungsten used for wiring as an electrode current collector is placed on the entire surface of the inner bottom of the convex container and penetrates the wall of the convex container and is electrically connected to the connection terminal A 103. The electrode current collector and the positive electrode active material 106 are bonded by the carbon-containing conductive adhesive 1111. There is no special requirement for bonding the electrode current collector and the positive electrode active material 106 and may just be placed thereon. The anode includes an electrode current collector and a cathode active material 106.

Nickel plating to form the brazing material 1082 is applied to a portion of the sealing plate 102 on the side of the container. The sealing plate 102 and the negative electrode active material 107 are previously joined by the carbon-containing conductive adhesive 1112. The negative electrode includes a sealing plate 102 and a negative electrode active material 107. A pair of positive and negative electrodes form a pair electrode.

After the cathode and anode, the separator 105 and the electrolyte solution inside the container and covered with a sealing plate 102, the sealing plate on all opposing sides by a parallel seam welder using resistance welding principle Welding of 102 is performed. High reliability sealing was obtained by the method described above.

The convex container 101 is preferably an insulator and a heat resistant material such as heat resistant resin, glass, ceramic or ceramic glass. As a manufacturing method, wiring and lamination | stacking are carried out by low temperature melting glass or glass ceramic by conductor printing, and it can bake at low temperature. Optionally, lamination can be carried out by laminating with alumina green sheets by conductor printing.

The material of the sealing plate and the metal ring 109 preferably has a coefficient of thermal expansion similar to that of the convex container 101.

For example, when using alumina having a thermal expansion coefficient of 6.8 × 10 ⁻⁶ ° C. for the convex container 101, cobalt having a thermal expansion coefficient of 5.2 × 10 ⁻⁶ ° C. is used as the metal ring and the sealing plate.

In addition, in order to improve the reliability after welding, the same cobalt as the metal ring is preferably used for the sealing plate 102. This is because the sealing plate can be heated after welding on the surface of the equipment (circuit board), ie during reflow soldering.

In addition, a part of the wiring forming the electrode current collector is preferably made of tungsten, palladium, silver, platinum or gold having good corrosion resistance, and can be formed by a thick film method. In addition, aluminum, titanium or carbon may also be used. When wiring is used for the bottom surface of the convex container 101 as an electrode current collector on the anode side, gold, aluminum or tungsten is particularly preferable. This can avoid melting the material when a positive potential is applied using a high resistance voltage material. In addition, in order to improve conduction between the electrode and the wiring, the use of a carbon-containing conductive adhesive is effective. In addition, in the case of using a low withstanding voltage material, it is effective to apply only the conductive adhesive-containing carbon to the metal of the electrode current collector over the entire surface and then sinter so as to cure the same to form the conductive layer. When aluminum is used to apply the electrode current collector, thermal spraying or plating from room temperature molten salts (butyl pyridinium chloride plating bath, imidazolium chloride bath or deposition) is performed. Can be used.

At portions of the contact terminal A 103 and the contact terminal B 104, a layer of nickel, gold, tin or solder is preferably placed for soldering with a substrate (circuit board). It is also preferable that a layer of nickel or gold having a good affinity with the bonding material is placed on the edge of the convex container 101. The metal layer forming method may include, for example, a gas phase method such as plating or vapor deposition.

It is effective to install nickel and / or gold foil as a brazing material on the surface joined by the metal ring 109 and the sealing plate 102. Although the melting point of gold is 1063 ° C and the melting point of nickel is 1453 ° C, the melting point is lowered below 1000 ° C by forming an alloy of gold and nickel. The metal layer forming method may include, for example, a gas phase method such as plating or vapor deposition, a cladding or a thick film method using printing. The thick film method using plating or printing is particularly preferable in view of cost.

However, it is necessary to reduce impurity elements such as P, B, S, N, and C to 10% or less in the layer of the brazing material. In particular, care should be taken when using plating. For example, in electroless plating, B tends to invade P and dimethylamine borane in sodium hypophosphite as reducing agent. In electrolytic plating, care should be taken because it may invade with additives such as brightening agents or anions. By adjusting the amounts of reducing agents, additives and the like, it is necessary to limit the amount of impurity to penetrate to 10% or less. If more than 10% is bonded, an intermetallic compound is formed on the bonding surface causing cracks.

When nickel is used as the brazing material 1082 on the side of the sealing plate 102, gold is preferably used as the brazing material 1082 on the side of the convex container 101. Gold and nickel ratios are preferably between 1: 2 and 1: 1, and the melting point of the alloy is lowered, thereby lowering the welding temperature and further improving the bonding property.

For welding the joints, parallel seam welding using resistance welding can be used. After temporarily securing the sealing plate 102 and the convex container 101 by spot welding, the roller-type electrode is pressed against two opposite sides of the sealing plate 102 and the current is supplied to weld according to the resistance welding principle. Is done. Sealing can be obtained by welding the four sides of the sealing plate 102. Since the current is supplied pulsating as the roller electrode rotates, a seam state after welding is obtained. A complete seal cannot be achieved unless the pulse width is controlled so that separate welds follow pulse overlap with each other.

In welding to a cell or a capacitor containing an electrolyte (liquid), parallel seam welding using resistance welding is particularly preferred, which has a low thermal resistance to vaporization and less leakage of electrolyte solution in the cell than other methods.

The separator used is preferably a heat resistant nonwoven fabric. For example, in the separator which consists of a roll porous film, although heat-resistant, it shrink | contracts in a rolling direction by heat at the time of seam welding which uses the resistance welding method. As a result, internal short circuits are likely to occur. The separator which uses heat-resistant resin or glass fiber with small shrinkage property is satisfactory. As the resin, polyphenylene sulfide (PPS) and polyetheretherketone (PEEK) are advantageous. Glass fibers are particularly effective. In addition, porous ceramics and polyfluoro-resin bodies may also be used.

In order to prevent an internal short circuit, it is effective to install a step inside the convex container 101 and to place a separator at the step. As shown in FIG. 4, the thickness of the metal ring 109 is reduced to be smaller than the wall on the side of the convex container 101 to form the step 110, and the separator is placed in this step. This can significantly reduce internal short circuits. In addition, as shown in FIG. 5, it is effective to provide a step 1101 on the side wall of the convex container 101.

The shape of the nonaqueous electrolyte cell or electric double layer capacitor of the present invention is basically optional. The shape of the conventional electric double layer capacitor obtained by the crimping and sealing shown in Fig. 2 is substantially limited to the circle. Therefore, when arranged on a substrate (circuit board) together with most other rectangular electronic components, wasteful void space is inevitably formed. Since the electric double layer capacitor of the present invention can also be designed in a rectangular shape and does not have protrusions such as terminals, it can be effectively placed on the substrate.

According to the nonaqueous electrolyte battery or the electric double layer capacitor of the present invention, since the connection terminal is integrated with the convex container and placed on the outer bottom of the container, the space of the substrate (circuit board) can be saved. Moreover, it can be processed by reflow soldering by consisting of a heat resistant material.

Claims (20)

A pair of positive and negative electrode pairs, a separator separating the positive and negative electrodes, an electrolyte, a convex container comprising the separator and the electrolyte, and a sealing plate for sealing the convex container In a chemical cell, a metal layer lies at the edge of the convex container, the sealing plate has a coefficient of thermal expansion similar to that of the convex container, and the convex container and the sealing plate are joined by welding. An electrochemical cell, wherein the thickness of the metal layer is thinner than the sum of the electrode and the separator located on the sealing plate side. The electrochemical cell of claim 1, wherein the metal layer comprises a metal ring and a brazing material, the metal ring has a coefficient of thermal expansion similar to that of the convex container, and the convex container and the sealing plate are joined by seam welding. . The electrochemical cell of claim 2, wherein the convex container and the sealing plate are joined by parallel seam resistance welding. The electrochemical cell of claim 2, wherein the convex container comprises an insulator. The electrochemical cell of claim 1, wherein the convex container comprises ceramic or ceramic glass. 3. The electrochemical cell of claim 2, wherein the metal ring comprises an alloy containing cobalt, nickel and iron, and the brazing material is nickel and / or gold foil formed on the metal ring. The electrochemical cell of claim 1, wherein the sealing plate comprises a metal on which a solder material is formed on a surface of a side surface joined together with a convex container. The electrochemical cell of claim 1, wherein the metal of the sealing plate comprises an alloy containing cobalt, nickel, and iron, and the brazing material formed on the surface of the side joined with the convex container is nickel and / or gold foil. The electrochemical cell of claim 2, wherein the solder material is formed by plating, printing, or cladding. The electrochemical cell of claim 7, wherein the solder material is formed by plating, printing, or cladding. delete The electrochemical cell according to claim 1, wherein a step is provided inside the convex container and a separator is placed on the step. The electrochemical cell of claim 1, wherein an electrode current collector is placed on a bottom surface of the convex container. The electrochemical cell of claim 13, wherein the electrode current collector comprises a material composed of any one material selected from tungsten, aluminum, titanium, carbon, palladium, silver, platinum, and gold. An electrochemical cell according to claim 13, wherein a conductive layer comprising carbon is further provided in the electrode current collector on the bottom surface of the convex container. The electrochemical cell of claim 1, wherein the separator comprises a nonwoven fabric. The electrochemical cell of claim 1, wherein a main component of the separator comprises polyphenylene sulfide, polyetheretherketone, polyfluororesin, or glass fiber. The electrochemical cell of claim 1, wherein the metal layer is formed by plating, printing, or cladding. An electrochemical cell comprising a positive electrode and a negative electrode, a separator separating the positive electrode and the negative electrode, an electrolyte, a convex container including the double electrode, the separator and the electrolyte, and a sealing plate for sealing the convex container. Placed on the edge of the convex container, the sealing plate has a coefficient of thermal expansion similar to that of the convex container, the convex container and the sealing plate are joined by resistance welding, An electrochemical cell, wherein the thickness of the metal layer is thinner than the sum of the electrode and the separator located on the sealing plate side. The electrochemical cell of claim 19, wherein the convex container and the sealing plate are joined by parallel seam welding.

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