JP2013030750A - Electrochemical cell and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable large current discharge in an electrochemical cell using a small exterior container.SOLUTION: An electrochemical cell is composed of: an exterior container comprising a base 1 and a lid 6; a cell 7 housed in the base 1; and an electrolyte. The electrochemical cell has pad films 2 formed on an inner side surface of the base 1 and composed of at least one valve metal; and connection terminals 4 provided on an outer side surface of the base 1 and electrically connecting with the pad films 2. Cell leads 8, which are extension parts of the cell, are respectively connected with the pad films 2 through welding.

Description

  The present invention relates to an electrochemical cell.

  Electrochemical cells have been used as backup power sources for clock functions, backup power sources for semiconductor memories, standby power sources for electronic devices such as microcomputers and IC memories, solar watch batteries, and power sources for driving motors. Is being studied as a power storage unit for electric vehicles and an auxiliary power storage unit for energy conversion and storage systems.

  In addition, since conventional electrochemical cells have a round shape like coins and buttons, it is necessary to weld terminals to the case in advance to perform reflow soldering, which increases the number of parts and the number of manufacturing steps. In this respect, the cost was increased. Further, it is necessary to provide a terminal space on the substrate, and there is a limit to downsizing.

  In order to solve such a problem, an electric double layer capacitor in which a power generation element (hereinafter referred to as a cell) and an electrolyte are housed in a container having a recess and the opening is sealed with a lid has been proposed. (For example, patent document 1).

JP 2001-216852 A

  The electrochemical cell having the above configuration is suitable for a memory backup application, and the discharge current of the electrochemical cell is in the range of several μA to several mA at most. However, as an electrochemical cell, a current of several hundred mA to several A is discharged with a pulse width of several hundred milliseconds to several seconds to blink a light source such as an LED provided in an electronic device, or a small motor. A new application such as intermittent driving has come out (hereinafter referred to as a large current discharge application). In the electrochemical cell having the above-described configuration, the connection resistance value may be several Ω, which causes a large voltage drop at the start of discharge, making it difficult to satisfy a predetermined function.

  An object of the present invention is to enable a large current discharge in an electrochemical cell using a small outer container.

In order to achieve the above object, the present invention adopts the following configuration.
The invention according to claim 1 is an electrochemical cell comprising an outer container made of a base and a lid, a plurality of cell leads that are extensions of the cell, a cell housed in the outer container, and an electrolyte. At least one cell lead having a pad film made of a valve metal formed on the inner side surface of the base and a connection terminal provided on the outer side surface of the base and electrically connected to the pad film. Is an electrochemical cell connected to the pad film by welding.
According to the first aspect of the invention, the cell lead and the pad film are connected by welding, thereby realizing an electrochemical cell that realizes a connection resistance value that is significantly lower than that of the conventional method using a conductive adhesive. it can. Therefore, large current discharge becomes possible.

The invention according to claim 2 is the electrochemical cell according to claim 1, wherein the thickness of the pad film is 5 μm or more and 100 μm or less.
The invention according to claim 3 is the electrochemical cell according to claim 1, wherein the thickness of the pad film is 10 μm or more and 30 μm or less.
According to the second and third aspects of the invention, it is possible to prevent the electrode located under the pad film from being melted, and at the same time, to join the cell lead without damaging the base member by welding. Therefore, large current discharge becomes possible.

The invention according to claim 4 is the electrochemical cell according to any one of claims 1 to 3, wherein the pad film contains aluminum.
According to the invention which concerns on Claim 4, by including aluminum in a pad film | membrane, a pad film | membrane is soft and it is easy to weld, Furthermore, the connection resistance by welding can be made small by the low electrical resistivity which aluminum itself has. Moreover, it is chemically stable by containing aluminum, and stable large current discharge is enabled over a long period of time.

The invention according to claim 5 is the electrochemical cell according to any one of claims 1 to 4, wherein the welding is ultrasonic welding or beam welding.
According to the invention of claim 5, by using ultrasonic welding or beam welding, the connection portion can be efficiently provided only in a local region without damaging the base member, and the connection portion is An electrochemical cell having a sufficiently low connection resistance value can be realized because it causes diffusion of atoms at the bonding interface of the member. Therefore, large current discharge becomes possible.

The invention according to claim 6 is the electrochemical cell according to any one of claims 1 to 5, wherein the base is made of ceramic or glass.
According to the invention concerning Claim 6, the electrochemical cell with low wiring resistance and connection resistance is realizable using glass. Since a long glass plate can be used as a raw material, it is possible to reduce the manufacturing cost by increasing the number of products.

The invention according to claim 7 is the electrochemical cell according to any one of claims 1 to 6, wherein the cell lead is made of aluminum, nickel, or copper.
According to the invention which concerns on Claim 7, it is possible to restrain connection resistance value low enough.

  The invention according to claim 8 is the electrochemical cell according to any one of claims 1 to 7, wherein, of the cell leads, both the positive and negative cell leads are welded to the pad film. is there.

The invention according to claim 9 is the electrochemical cell according to any one of claims 1 to 7, wherein the cell lead of the negative electrode is electrically connected to the lid.
According to the ninth aspect of the invention, the connection resistance value can be kept sufficiently low.

The invention according to claim 10 is characterized in that the pad film and the connection terminal are connected via an in-base terminal embedded in the base. This is an electrochemical cell.
According to the tenth aspect of the present invention, the wiring pattern can be shortened by having at least one conductive base terminal in the base, so that the wiring resistance value can be reduced. Therefore, large current discharge becomes possible.
According to the tenth aspect of the present invention, the length between the pad film and the connection terminal is achieved by connecting the pad film and the connection terminal through the inner surface of the base and the outer surface of the base. Can be made sufficiently short. Therefore, the wiring resistance can be kept sufficiently low. In addition, an increase in the wiring resistance value can be suppressed even when the dimensions of the outer container are increased. Therefore, large current discharge becomes possible.

According to an eleventh aspect of the present invention, in the outer container, the concave base and the plate-shaped lid are sealed directly or via a bonded metal member. It is an electrochemical cell as described in any one.
According to the invention which concerns on Claim 11, it is possible to restrain connection resistance value low enough.

According to a twelfth aspect of the present invention, the base includes a first base that is an outer layer of the exterior container and a second base that is an inner layer, and the terminal in the base penetrates the second base. 11. The electrochemical cell according to claim 10, wherein the connection terminal extends on a boundary surface between the first base and the second base, and is connected to the terminal in the base.
According to the invention which concerns on Claim 12, compared with the system which penetrates a through-hole to the bottom face of a base, the leak to the base outer surface which may generate | occur | produce when an electrolyte contains a liquid can be suppressed. Moreover, wiring resistance can be suppressed. Furthermore, since the cell lead and the pad film are connected by welding, the connection resistance value can be remarkably reduced as compared with the conductive adhesive.

The invention according to claim 13 is characterized in that the pad film is connected to the connection terminal via a wiring pattern extending on the inner side surface of the base. The electrochemical cell according to one item.
According to the thirteenth aspect of the present invention, leakage to the outer surface of the base that may occur when the electrolyte contains a liquid can be suppressed. Furthermore, since the cell lead and the pad film are electrochemical cells having a structure connected by welding, the connection resistance can be remarkably reduced.

The invention according to claim 14 is the electrochemical cell according to claim 13, wherein the wiring pattern is covered with a protective film so as not to be exposed to the electrolyte.
According to the invention of claim 14, the wiring pattern is not exposed to the electrolyte. Therefore, the electrochemical cell can maintain stable quality for a long time without dissolving the wiring pattern.

The invention according to claim 15 is the electrochemical cell according to any one of claims 1 to 11, wherein the base has a flat plate shape and the lid has a concave shape.
According to the invention which concerns on Claim 15, wiring resistance and connection resistance can fully be suppressed. Further, a deep concave container can be obtained by, for example, performing a deep drawing process on a metal lid. Therefore, a large-capacity electrochemical cell can be realized without significantly increasing the manufacturing cost.

The invention according to claim 16 is the electrochemical cell according to claim 15, wherein the base or the lid has a small hole, and the small hole is sealed with a sealing plug.
According to the invention which concerns on Claim 16, there exists an advantage which can be welded before inject | pouring electrolyte.

The invention according to claim 17 is characterized in that the base member has a step on a surface in contact with the joining member, and the metal joining member is fitted in the step. It is a chemical cell.
According to the invention of claim 17, even if the cell is placed in the lid after filling the electrolyte with the lid upside down, the electrolytic mass overflowing from the lid can be reduced. Therefore, the base and the lid can be easily welded even when the electrolyte is filled. Therefore, a small hole in the lid is unnecessary, and a sealing step using a sealing plug can be omitted.

The invention according to claim 18 is characterized in that the base member and the lid have a flat plate shape and are sealed through a metal side wall. Cell.
According to the eighteenth aspect of the present invention, the wiring resistance and the connection resistance can be sufficiently suppressed. In addition, a standard product such as a hollow pipe can be used as the cylindrical metal used as the side surface. Therefore, a large-capacity electrochemical cell can be realized without significantly increasing the manufacturing cost.

The invention according to claim 19 is the electrochemical cell according to claim 18, wherein the cell lead of the positive electrode is connected to the metal side wall.
According to the nineteenth aspect of the present invention, the connection resistance value can be kept sufficiently low.

The invention according to claim 20 includes a pad film forming step of forming a pad film on the inner side surface of the base constituting the exterior container, a cell lead / pad film welding step of connecting the cell lead and the pad film by welding, and a cell. A method for producing an electrochemical cell comprising a step of storing in a base, a step of filling an electrolyte, and a step of bonding a lid to the base.
According to the invention which concerns on Claim 20, the pad film formation process which forms a pad film in the inner surface of the base which comprises an exterior container, The cell lead / pad film welding process which connects the said cell lead and the said pad film by welding, Since the method includes the step of housing the cell in the base, the step of filling the electrolyte, and the step of bonding the lid to the base, an electrochemical cell having a sufficiently low connection resistance can be realized.

The invention according to claim 21 is the method for producing an electrochemical cell according to claim 20, wherein the welding process between the cell lead and the pad film uses ultrasonic welding or beam welding.
According to the invention of claim 21, since ultrasonic welding or beam welding is used, the connection portion can be efficiently provided only in a local region without damaging the ceramic member serving as a base, and the connection portion is An electrochemical cell having a sufficiently low connection resistance value can be realized because it causes diffusion of atoms at the bonding interface of the member.

  According to the present invention, the cell lead and the pad film are connected by welding, so that a connection resistance value that is remarkably lower than that of the conventional method using a conductive adhesive is realized, and a large current discharge is possible. A chemical cell can be realized.

It is a figure explaining the electrochemical cell of this invention. It is a figure which shows the relationship of the pad film | membrane of the electrochemical cell of this invention, a terminal in a base, and a connection terminal. It is a figure explaining welding of the cell lead and pad film of the electrochemical cell of the present invention. It is a figure which shows the modification of the electrochemical cell of this invention. It is a figure which shows the modification of the electrochemical cell of this invention. It is a figure which shows the modification of the electrochemical cell of this invention. It is a figure which shows the modification of the electrochemical cell of this invention. It is a figure which shows the modification of the electrochemical cell of this invention. It is a figure which shows the manufacture flow of the electrochemical cell of this invention. It is a schematic diagram explaining the breakdown of the resistance value of Example 1 of this invention. It is a figure which shows the conventional electrochemical cell.

  The electrochemical cell of this invention is demonstrated based on drawing. The electrochemical cell of the present invention is mainly used by being mounted on a substrate inside a personal computer or a small portable device. Fig.1 (a) is an external view of the electrochemical cell of this invention. As an example, a rectangular parallelepiped shape is shown, but a track shape or a cylindrical shape may be used. The electrochemical cell of the present invention includes a base 1 that functions as a container that houses a cell that is a power generation element, and a lid 6 that functions as a sealing plate for hermetically closing the opening. The outer packaging container of the electrochemical cell of the present invention is sealed with the base 1 and the lid 6.

  FIG.1 (b) is a figure which shows the AA cross section of (a). The cell 7 is accommodated in the concave base 1, further filled with an electrolyte, and hermetically sealed by a lid 6 pressed against a bonding metal member 5 provided around the upper surface of the concave base 1. Yes. The cell 7 includes an active material and a current collector made of a metal carrying the active material (hereinafter referred to as a metal current collector) with a pair of electrode sheets inserted with an insulating separator, and a winding method or a lamination method. It is composed of At the ends of the positive and negative electrode metal current collectors, the metal current collector itself was thinly extended, or another thin thin plate or a wire-like lead was mechanically connected to form an extension. In the present invention, this is represented by a cell lead 8. The cell leads 8 of the positive electrode and the negative electrode are connected by welding to a pad film 2 which is a pair of current collector metal films arranged in parallel with the base inner surface 1a of the concave base 1. The bottom surface of the pad film 2 is provided with a hole that penetrates and connects the base inner surface 1a and the base outer surface 1b substantially vertically. The hole is filled with a refractory metal such as tungsten to satisfy the hermeticity. In the present invention, the base inner terminal 3 refers to a terminal embedded in the base, and in addition to the conductive through hole filled with metal, a metal film is formed on the inner surface of the through hole to make it electrically conductive. The inside includes a material filled with an insulating material such as glass so as to satisfy airtightness. The base inner terminal 3 electrically connects the pad film 2 and the connection terminal 4 formed on the base outer surface 1b. The positive electrode and the negative electrode of the cell 7 are connected to the mounting pattern of the substrate mounted by the connection terminal 4.

Here, before describing the present invention in detail, the influence of the connection resistance value and the wiring resistance value on the discharge characteristics will be described by taking an electric double layer capacitor as an example.
It is assumed that the rated voltage of the electric double layer capacitor is 2.6V and the capacitance is 1F. The value of the equivalent series resistance is the sum of the ion diffusion resistance value and the electronic resistance value A of the cell, the wiring resistance value of the outer container containing the cell, and the connection resistance value between the cell lead and the pad film (this wiring resistance value and connection And the discharge characteristics of the electric double layer capacitor are evaluated.

  Table 1 shows the voltage drop of the electric double layer capacitor when pulsed discharge current flows by setting the value of A of the equivalent series resistance to 50 mΩ and setting B to 3 types (cases 1 to 3). It is calculated. The current was 1 A, and the discharge pulse width was 1000 msec (1 second).

  Here, the case 1 was designed to have a value of B, that is, a wiring resistance value of the outer container and a connection resistance value between the cell lead and the pad film, and was set to 20 mΩ. The total value of the equivalent series resistance is the sum of A and B and is 70 mΩ. Since the discharge current is 1A, the voltage drop generated by the equivalent series resistance is the product of the current and the equivalent series resistance, that is, 1A × 0.07Ω = 0.07V. On the other hand, since the capacity is 1F, the voltage drop involving the capacity is (1A × 1 sec) / 1F, that is, 1V. Therefore, in case 1, since a current of 1 A is discharged for 1000 msec, 0.07 + 1 = 1.07 V, which is the sum of the voltage drops of both.

  Since the electric double layer capacitor was initially charged at 2.6 V, the electric double layer capacitor was maintained at a voltage of 2.6-1.07 = 1.53 V when this discharge was completed. become. That is, in case 1, it can be said that a 1 m current discharge application of 1000 msec can be realized.

  Cases 2 and 3 in Table 1 are calculated in the same manner. Case 3 assumes an electric double layer capacitor in which the cell lead and the pad film are connected by a connecting means such as a conventional conductive adhesive, and the value of B is 2000 mΩ, which is the total equivalent series resistance. Reaches 2050 mΩ. Therefore, only a voltage drop due to the contribution of the equivalent series resistance is 2.05 V, and when a voltage drop of 1 V due to the capacitance is added to this, it becomes 3.05 V, which exceeds the initial rated voltage. That is, the electric double layer capacitor cannot be discharged in the middle of a pulse width of 1000 msec, and a large current discharge cannot be realized.

  Case 2 corresponds to an intermediate case 1 and case 3. That is, since the wiring resistance value of the outer container and the connection resistance value between the cell lead and the pad film remain at 500 mΩ, the total value of the equivalent series resistance is 550 mΩ, and the voltage drop contributed by the equivalent series resistance is It is 0.55V. Therefore, even if the voltage drop corresponding to the capacity contribution is included, the total value of the voltage drop stays at 1.55 V, and the rated voltage value is 2.6 V or less, so a large current discharge of 1000 msec can be realized at 1 A. is there.

  In the above three cases, it was shown whether a large current discharge is possible. In cases 1 and 2 where the value of B is low, large current discharge was possible, but it should be noted that the contribution of the voltage drop due to the value of B is proportional to the discharge current. If the discharge current is 2A, the voltage drop due to the equivalent series resistance of case 1 is 2A × 0.07Ω = 0.14V, and the sum of the voltage drop 2V due to the capacitance is 2.14V. Large current discharges are still possible. On the other hand, in the case 2, the voltage drop corresponding to the equivalent series resistance is 2A × 0.55Ω = 1.1V, and the sum of the voltage drop 2V corresponding to the capacitance is 3.1V, and the rated voltage 2. Exceeding 6V, large current discharge is no longer possible.

  As described above, since the magnitude of the B greatly affects whether or not a large current can be discharged, the wiring resistance value and the connection resistance value of the cell lead and the pad film are examined in units of mΩ when designing the electric double layer capacitor. There is a need to continue to.

  Although the value of B is the sum of the connection resistance value and the wiring resistance value, these two relationships will be further described with reference to Table 2. Tables 2 to 4 show the upper limit (in units of wiring resistance) from the range of desirable voltage drop at the beginning of discharge when the connection resistance value per pole on one side is 5 types of 1 mΩ, 5 mΩ, 10 mΩ, 30 mΩ, and 100 mΩ. mΩ) is obtained by calculation. Here, the wiring resistance value is the sum of the wiring resistance values of the positive electrode and the negative electrode.

  In practice, the voltage drop at the initial stage of discharge is preferably within 0.3V. More preferably within 0.2V. For example, if the charging voltage is 2.6 V and the initial voltage drop is 0.3 V, the initial voltage of the discharge contributing to the discharge energy is 2.3 V minus the voltage drop. The discharge energy in this case is maintained at about 78% when compared with the discharge energy when the initial voltage is 2.6 V, which is an acceptable value. The ratio is improved to about 85% when the initial voltage drop is 0.2V, and to about 92% when the voltage drop is 0.1V.

  In a small electrochemical cell, the value of A of the equivalent series resistance of a single electrochemical cell is in the range of several tens of mΩ to several hundreds of mΩ, but here, a case of 150 mΩ was calculated as a representative example. Table 2 shows the upper limit of the wiring resistance value of a single electrochemical cell, and Table 3 shows the upper limit of the wiring resistance value of one electrochemical cell when two single electrochemical cells are connected in series. Table 4 shows the upper limit of the wiring resistance value of one electrochemical cell when three single electrochemical cells are connected in series. Since it is an electrochemical cell, it is often used connected in series so as to have the required rated voltage. Therefore, it is desirable to be able to be used even when connected in series.

  Here, the upper limit of the wiring resistance value was calculated on the assumption that the initial voltage drop was 0.3 V described above. In Table 2, the horizontal lined column indicates that the upper limit of the wiring resistance value is 0 mΩ or less when the voltage drop is 0.3V. That is, it means that the initial voltage drop exceeds 0.3V.

  Table 2 shows that when the connection resistance value is 1 mΩ, the upper limit of the wiring resistance value is 148 mΩ when the discharge current is 1 A. When the discharge current is further increased to 1.75 A, the upper limit of the wiring resistance value is reduced to 19 mΩ. In this way, in order to allow a discharge current value in a wide range to flow to some extent, the upper limit of the wiring resistance value is set to, for example, 10 mΩ in consideration of the maximum current value. The upper limit value when the connection resistance value is 5 mΩ is only 8 mΩ lower than that when the connection resistance value is 1 mΩ. Also in this case, if the wiring resistance value is manufactured to be 10 mΩ or less, it is possible to discharge up to 1.75A. When the connection resistance value is 10 mΩ, the voltage drop exceeds 0.3 V at a discharge current of 1.75 A. However, if the wiring resistance value is on the order of 20 mΩ, the discharge current can flow up to 1.5 A.

  On the other hand, when the connection resistance value is 100 mΩ, the current value at which the initial voltage drop can be suppressed to 0.3 V or less is 0.75 A or less, which is substantially unsuitable for large current discharge applications. When the connection resistance value is 30 mΩ, the wiring resistance value margin is improved compared to when the connection resistance value is 100 mΩ. However, when a current of 1.5 A is passed, the initial voltage drop exceeds 0.3 V. Therefore, the connection resistance value is still large. Therefore, the connection resistance value is preferably 10 mΩ or less.

  When two series are connected, as shown in Table 3, since the equivalent series resistance A is twice 150 mΩ, the upper limit of the wiring resistance value is greatly suppressed, and the maximum discharge current needs to be reduced. is there. For example, when the discharge current is 1 A, the voltage drop due to the equivalent series resistance A is 1 A × 0.3Ω = 0.3 V, so even if the contact resistance value is 1 mΩ, the upper limit column of the wiring resistance value is It is a horizontal line. In the case of two series, the discharge current is 1 A or less under the condition that the voltage drop is 0.3 V or less. At a discharge current of 0.9 A, the upper limit of the wiring resistance value is 6.5 mΩ when the connection resistance value is 5 mΩ, but when the connection resistance value is 10 mΩ, the voltage drop is 0.3 V at the discharge current of 0.90 A. And a difference appears compared to the case where the connection resistance value is 5 mΩ or less. Therefore, considering the series connection application, the connection resistance value is preferably 5 mΩ or less.

  In the case of 3 series, the value of A of the equivalent series resistance is 150 mΩ × 3 = 450 mΩ, so that the maximum current is also 0.3 V / 0.45Ω, that is, about 0 in order to make the voltage drop 0.3 V or less. .65A. As shown in Table 4, when the connection resistance value is 5 mΩ, 0.6 A discharge is possible, but the upper limit of the wiring resistance value is 6 mΩ. When the connection resistance value is 1 mΩ, the upper limit of the wiring resistance value is 14 mΩ. In this way, as the number of stages connected in series increases, the influence of the connection resistance value on the wiring resistance value will appear greatly, so if you consider only the specifications with only a single electrochemical cell, Therefore, the above examination is necessary.

  The wiring resistance value depends on the resistivity and area of the pad film and the connection terminal, and the wiring and structure connecting them. Regarding the increase in the wiring resistance value caused by the longer wiring, the contribution of the terminal in the base of the present invention is large. In particular, when the capacity of the electric double layer capacitor is increased to increase or lengthen the discharge current and discharge time of the large current discharge, the dimensions of the container increase, and the wiring tends to become longer accordingly. By directly connecting the front and back of the base using the terminals in the base, it is possible to greatly reduce the wiring resistance value.

  On the other hand, the reduction of the connection resistance value between the cell lead and the pad film greatly contributes to welding. As a conductive adhesive for an electrochemical cell, a conductive filler is made of carbon or graphite, and a binder is preferably a finol resin. However, the connection resistance value varies greatly depending on the application conditions of the conductive adhesive, the surface condition of the metal to be connected, the thermosetting conditions, the mounting temperature conditions of the electrochemical cell on the substrate, and the production lot of the conductive adhesive. In some cases, it is difficult to design and manage the connection resistance value in units of mΩ required for large current discharge applications.

  2A and 2B are views showing the base inner surface 1a and the base outer surface 1b of the base 1, respectively. A pair of pad films 2 made of a conductive material are disposed on the base inner surface 1a shown in FIG. Four base inner terminals 3 indicated by broken lines are provided on the lower surface of the pad film 2, and are connected vertically to connection terminals 4 (also indicated by broken lines) arranged on the outer surface of the base 1.

  Here, the pad films 2 are juxtaposed in the longitudinal direction of the base as an example, but they can be juxtaposed in the short side direction or in the diagonal direction of the longitudinal direction. The pad film 2 is not necessarily formed on the base terminal 3.

  The pad film 2 is a film made of a chemically stable valve metal such as aluminum or titanium, and is made of a material that is difficult to dissolve. These films can be provided by a known film forming method such as vapor deposition, ion plating, or sputtering. In the case of these methods, first, a metal such as tungsten is filled and fired in the through holes by a printing method or the like, and the airtight base terminal 3 is finished. When forming a film in a vacuum, for example, a mask made of metal or the like patterned so as to have two openings spatially separated from each other is prepared to form the positive and negative pad films 2, respectively. The base 1 is evacuated to a predetermined degree of vacuum with a vacuum exhaust system and then evaporated with the valve metal material, or the target made of the valve metal material is physically hit with ions to blow the material. A film is formed on the inner surface of the film. In these film forming methods, since the film forming conditions are easily controlled, a high-density film having a low resistivity and a low liquid penetration property can be formed.

  The aluminum film can also be formed by screen printing. A technique has been developed that can form a wiring pattern at a temperature of 150 ° C. or lower even for aluminum that is easily oxidized at high temperatures. Since it is a printing method, it is thicker than a thin film formation technique such as vapor deposition, and a thick film of several tens of microns is easy.

  Furthermore, the aluminum film can be produced by electroplating. It is known that a film formed with a film thickness of about 40 μm using a plating solution composed of dimethyl sulfone and aluminum chloride has a smooth surface and a uniform film inside.

  A pair of connection terminals 4 are provided on the base outer surface 1 b shown in FIG. 2B so as to face the pad film 2. The connection terminal 4 is fixed to the substrate by cream solder or the like provided on the pattern of the mounting substrate by reflow processing or the like. For example, the connection terminal 4 is provided with a plating film made of nickel and gold on a tungsten pattern formed by a printing method. Tungsten and these plating materials are also patterned in the concave portion on the side of the base indicated by the reference numeral 1c and function as a part of the connection terminal.

  Subsequently, the thickness of the pad film 2 will be described. The film thickness is desirably 5 μm or more and 100 μm or less. The range of 10 μm or more and 30 μm is preferable. If the film thickness is thin, the fine porous existing inside the film is connected, and the electrolyte easily penetrates tungsten under the pad film to cause electrolytic corrosion of tungsten. When connected, the welding conditions are extremely limited, making it difficult to achieve reliable joining.

  An aluminum film with a thickness of 5 μm is formed on a soda-lime glass plate with a thickness of about 1.3 mm by ion plating, and then an aluminum thin plate with a thickness of 80 μm is welded by ultrasonic welding. did. In one sample out of five cell leads, generation of minute cracks was observed in the glass plate. Therefore, 5 μm is a practical lower limit for the film thickness. Practically, the film thickness is desirably 10 μm or more.

  On the other hand, the deposition rate of aluminum by an evaporation method or an ion plating method is 3 μm to 10 μm per hour. Considering the deposition time, a thickness of 30 μm or less is preferable. In this case, the film formation time is about 4 to 5 hours at the longest. When it is formed to a thickness of about 100 μm, the film formation time takes a long time, but the welding conditions when connecting to the cell lead 8 by welding can be widely taken, and there is a possibility that a crack is induced in the ceramic as a base. Can be very low.

  Next, a specific welding method between the cell lead 8 and the pad film 2 will be described with reference to FIG. FIG. 3A is a diagram showing the connection between the pair of cell leads 8 connected to the cell 7 and the pair of pad films 2. As shown in FIG. 3A, the tips of the pair of cell leads 8 are placed on the surface of the pad film 2 and then welded from the upper surface of the cell lead 8 to join the pad film 2 and the cell lead 8. By using welding, atomic diffusion of the material constituting each member occurs at the bonding interface between the cell lead 8 and the pad film 2, thereby enabling strong bonding. 3a in FIG. 3 (a) schematically shows a welded region. Since welding is used, even if there is a contamination such as a natural oxide film on the joint interface, it is possible to join with a sufficiently low connection resistance in the order of mΩ or less than mΩ. As a result, the connection resistance can be reduced from 1/10 to 1/100 as compared with a bonding method using a conductive adhesive or the like. In addition, it is possible to perform bonding with less variation in connection resistance value and less change with time.

  In addition, by setting a plurality of junction points, the connection resistance value can be further reduced and the tensile strength between the cell lead 8 and the pad film 2 can be improved. Therefore, the cell lead 8 is deformed and the cell is placed inside the container. In the manufacturing process in which the housing 7 is accommodated, it is possible to suppress the occurrence of defects such as welding peeling, and to improve mechanical reliability such as vibration resistance characteristics and drop impact characteristics of the completed electrochemical cell.

  Specifically, local welding methods such as ultrasonic welding, beam welding, and resistance welding are suitable for welding the cell lead 8 and the pad layer 2. That is, in these welding means, since the part to be welded is local, the thermal influence remains only in the vicinity of the welded portion, and the influence on the cell 7 itself can be avoided. Further, by changing the material and thickness of the cell lead 8, the material of the pad film 2 and the arrangement of the through holes, the influence on the components due to mechanical or thermal shock of welding can be reduced. With the above configuration, it is possible to avoid damage to the member due to the occurrence of cracks even in the base 1 made of a material such as ceramics.

  FIG. 3B is a diagram for explaining a specific method of ultrasonic welding. In ultrasonic welding, as shown in FIG. 3B, the cell lead 8 is first positioned and brought into close contact with the pad film 2, but at this time, the cell 7 hinders the movement of the ultrasonic welding tip 9. It is placed outside the base 1 so that it does not become. Next, the ultrasonic welding tip 9 is brought into contact with the upper surface of the cell lead 8 with an appropriate pressing force by a moving mechanism. The ultrasonic welding tip 9 is formed integrally with the tip of the horn or is attached separately to the tip of the horn. The tip end 9a of the tip 9 for ultrasonic welding is a portion to be a contact surface with the cell lead 8, and the surface thereof is provided with an uneven pattern so as to bite into the surface of the cell lead 8 properly ( (Nar processing) is preferred.

  After the ultrasonic welding tip 9 is brought into contact with the cell lead 8 with an appropriate pressure, when the ultrasonic welding machine applies an ultrasonic wave consisting of several tens of KHz to the horn, the ultrasonic welding tip 9 has a frequency. Rub the joints together. As a result, the interface between the cell lead 8 and the pad film 2 becomes a close contact surface between clean surfaces of the metal material, and can be pressed in a short time of several tens of milliseconds to several hundreds of milliseconds. The concave / convex pattern on the surface of the cell lead 8 indicated by the weld area 8a of the cell lead / pad film in FIG. 3 (a) is that the concave / convex pattern of the ultrasonic welding tip 9 is transferred by this ultrasonic welding. It is shown schematically. The region 8a indicated by the uneven pattern is a welding region, but when viewed microscopically, the joined portion is only the portion recessed by the convex processed at the tip of the ultrasonic welding tip 9. In other regions, a slight gap is maintained between the cell lead and the pad film.

  When the ultrasonic welding tip 9 abuts on the surface of the cell lead 8, it is preferable to take care not to cause a large impact, and the moving mechanism may be provided with an impact absorbing mechanism such as a damper. Thereby, damage to the base material can be reduced.

  Appropriate selection of dimensions for cell leads 8 (lead width and thickness), pad film 2 dimensions (vertical and horizontal dimensions and thickness), and ultrasonic welding tip 9 allows for various dimensions of electrochemical cells. Is possible. The width d of the ultrasonic welding region shown in FIG. 3 (a) may be 0.5 mm, which is convenient for manufacturing a small electrochemical cell. Further, in order to further increase the mechanical strength, even when ultrasonic welding is performed using the ultrasonic welding tip 9 designed to cover substantially the entire area of the pad film 2, it is possible to set appropriate welding conditions. The base terminal and base material are not affected, and a sufficiently large mechanical strength can be obtained.

  In ultrasonic welding, not only vibration but also thermal energy and mechanical pressure can be used in combination. 3A shows a thin plate-like example as the cell lead 8, a wire may be used, and the shape of the ultrasonic welding tip 9 may be appropriately deformed and used.

  Next, the case of beam welding will be described. As the beam welding, laser welding and electron beam welding are typical. These welds not only allow local processing, but also are non-contact methods, so that there is no deterioration due to heat and wear of the welding terminals. Therefore, reproducibility is good. In addition, since it has an energy density sufficient to melt the metal, it can be processed in a short time. In electron beam welding, the energy density is extremely high, the electron beam is highly scannable, and the cell 7 having the base 1 to be welded and the cell lead 8 is placed in a vacuum, and the electron beam is irradiated in the vacuum. It is the same as laser welding except for welding.

In laser welding, spot welding or seam welding (pulse oscillation or continuous oscillation) can be used. The case of spot welding with a YAG laser will be described below.
A laser oscillator, a transmission fiber, a coaxial CCD monitor for positioning and observing the surface of the base 1 and the cell lead 8 are prepared, and the cell lead 8 and the pad film 2 are brought into close contact with an appropriate pressure, and then the surface of the lead 8 Irradiate laser from side. When irradiating a laser, in order to prevent oxidation of the joint between the pad film 2 and the cell lead 8, an inert gas such as argon or nitrogen is blown or an inert gas atmosphere is used using a glove box or the like. Is desirable.

  FIG. 3C shows the connection of the cell lead 8 and the pad film 2 by laser welding. 8a shown by the black circle of the figure has shown the welding area | region where the laser was irradiated and was welded. Aluminum has a low absorptivity of 1064 nm of the YAG laser (high reflectivity material), but the laser irradiation part is heated, and the dissolution part gradually expands from the central part of the heating. The heating reaches the surface of the lower pad film 2 to be bonded from the lower surface of the cell lead 8, dissolves the surface portion of the pad film 2, and the cell lead 8 and the pad film 2 are bonded.

  Also in the case of laser welding, it is desirable to further reduce the connection resistance value by increasing the welding area, and to increase the mechanical strength of the welding. In FIG. We are welding.

  In FIGS. 3A and 3C, one cell lead is welded to one pad film, but the number of cell leads may be plural. When the length of the metal current collector supporting the active material is long, a plurality of cell leads can be provided on the metal current collector. In this case, it is preferable that the plurality of cell leads can be connected to one pad film because the resistance can be reduced.

  The ultrasonic welding and beam welding have been described above as the welding methods, but the welding means is not limited to this, and other means may be used. For example, a welding method such as spot resistance welding or arc welding can be used.

  Ceramics is a commonly used material as the base material of the outer container, but is not limited to ceramics. Soda lime glass and heat-resistant glass can also be used. Since a long glass can be used as a material, in the case of a small package, a large number of pieces can be set for one glass, and cost reduction of the base member can be expected. Further, as means for forming the recesses and through holes in these glasses, the recesses and the through holes can be formed simultaneously by using a chemical etching method, a physical method such as sandblasting, or a mold in a high temperature atmosphere. .

  In addition, after forming an aluminum film on the inner surface of the through hole, a glass paste whose thermal expansion coefficient is matched is filled in the through hole, and the binder inner terminal 3 is hermetically sealed by conducting binder removal and firing. Can be formed. In such a case, there is no concern that the base terminal 3 is dissolved. Therefore, it is not necessary to form the pad film 2 so as to cover the terminal 3 in the base. Moreover, the film | membrane which forms the inner surface of the terminal 3 in a base is not limited to aluminum, You may be a film | membrane containing other valve metals, such as titanium.

Next, the cell 7 will be described. The cell 7 has a separator made of an insulating material as a pair of positive and negative electrode sheets having an aluminum foil or copper foil having a thickness of 5 μm to 50 μm as a metal current collector and carrying an active material on the surface thereof by coating or bonding. It is a power generation element that is integrated by winding, stacking, folding, etc. In the case of an electric double layer capacitor, activated carbon or carbon is given as a typical material of the active material. In the lithium ion secondary battery, examples of the positive electrode active material include lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), and lithium iron phosphate (LiFePO ₄ ). As the negative electrode active material, for example, graphite, coke, silicon oxide, and the like are used. The active material paste is prepared by mixing the above active material with a conductive auxiliary agent, a binder, a dispersing agent, etc. and adjusting the viscosity to an appropriate viscosity, and by a method such as roller coating, screen coating, doctor blade method, Apply to both or one side of the current collector. After coating, a drying and pressing process is obtained to form an electrode sheet.

  The separator regulates the direct contact between the positive electrode and the negative electrode, and an insulating film having a large ion permeability and a predetermined mechanical strength is used. For example, in an environment where heat resistance is required, resins such as polytetrafluoroethylene, polyphenylene sulfide, polyethylene terephthalate, polyamide, and polyimide can be used in addition to glass fibers. Moreover, although it does not specifically limit regarding the hole diameter and thickness of a separator, It determines based on the electric current value of an apparatus used, and the internal resistance of an electrochemical cell. It is also possible to use a porous ceramic body as a separator.

  The electrolyte includes a non-aqueous solvent and a supporting salt. The electrolyte may be a liquid or a solid. As the nonaqueous solvent for the electrolyte, propylene carbonate, ethylene carbonate, γ-butyrolactone, sulfolane, acetonitrile, dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate is used as one or a mixture of two or more. In particular, it is preferable to use a single compound or a composite selected from solvents having a high boiling point such as propylene carbonate, ethylene carbonate, γ-butyrolactone, and sulfolane. By using these solvents, the vaporization of the solvent can be prevented in a high temperature environment, and the internal pressure of the container can be suppressed.

The supporting salt includes an electrolyte cation and an electrolyte anion. As the electrolyte cation, one or more salts such as a quaternary ammonium salt, a quaternary phosphonium salt, an imidazolium salt, a pyrrolidinium salt, a phosphonium salt, a thiocyanate salt, or a lithium salt are used. BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , or N (CF ₃ SO ₂ ) ₂ ⁻ is used as the electrolyte anion.

  The electrolyte is a polyethylene oxide derivative, or a polymer containing a polyethylene oxide derivative, a polymer containing a polypropylene oxide derivative or a polypropylene oxide derivative, a phosphate ester polymer, PVDF, etc., in combination with a non-aqueous solvent or a supporting salt, It can also be used in solid form.

An inorganic solid electrolyte of LiS / SiS ₂ / Li ₄ SiO ₄ can also be used. Furthermore, a pyridine-based, alicyclic amine-based, aliphatic amine-based, imidazolium-based ionic liquid, or amidine-based room temperature molten salt may be used as the electrolyte.

  Subsequently, sealing of the base 1 and the lid 6 will be described. The lid 6 is selected so that the coefficient of thermal expansion matches the bonding metal member 5 used for the lid bonding of the base 1, and a material such as Kovar, which is an iron / cobalt / nickel alloy, is used. Specifically, Kovar is a thin plate having a thickness of about 0.1 mm to 0.2 mm, and the surface thereof is subjected to electrolytic nickel plating or electroless nickel plating with a thickness of about 2 μm to 4 μm.

  In resistance seam welding, which is used as a method of welding the two, after the lid 6 is brought into contact with the joining metal member 5, two opposing trapezoidal roller electrodes are arranged at approximately two points on the long side of the lid 6. Then, a low voltage and large current is allowed to flow for a short time, and temporary welding (spot welding) of the lid 6 is performed. In this way, the lid 6 is temporarily fixed, and the position does not shift due to vibration or the like during the welding operation.

  Subsequently, for example, the base 1 and the lid 6 are moved and welded so that the long side is traced by the roller electrode from the end of the long side. Next, the base 1 and the lid 6 are rotated 90 degrees, and the short sides are similarly welded. In this way, welding is performed over the entire circumference of the lid 6. In both the above-described temporary fixing and the resistance seam welding, diffusion of gold and nickel occurs at the interface between the lid 6 and the bonding metal member 5, and an airtight and strong diffusion bonding layer is formed. Thereby, the lid 6 is hermetically sealed to the base 1.

  The base 1 and the lid 6 can be welded using laser scanning irradiation. After carrying out temporary welding in the same manner as described above, a laser beam is scanned and irradiated so as to make a round of the lid. Thereby, a diffusion bonding layer is formed at the interface between the lid 6 and the bonding metal member 5. In this case, it is possible to lower the melting temperature to the temperature of the brazing material by sticking a brazing material sheet made of silver and copper on the surface of the lid 6 on the joining side.

  When the electrolyte is made of a liquid solvent or a supporting salt at room temperature and the electrolyte is filled before sealing the lid 6, the place where the liquid exists at the interface between the lid 6 and the bonding metal member 5. There can be. Even in such a case, joining using seam welding is possible. Seam welding may be performed using a roller electrode or using laser scanning irradiation. The reason why airtight welding is possible even if liquid exists at the interface is considered to be that the liquid present at the interface evaporates and scatters because the temperature in the vicinity of the liquid increases rapidly during welding.

Then, the modification of invention is demonstrated. First, the modification regarding the structure of the terminal in a base is described.
FIG. 4 is a diagram showing a modification of the present invention. FIG. 4A is a diagram showing a cross section of this modification. FIG. 4B is a diagram showing a wiring pattern of this modification, and is a diagram showing an example of a solid wiring pattern. FIG. 4C shows another example of the wiring pattern of this modification. In the electrochemical cell shown in FIG. 4A, the base inner terminal 3 is not directly penetrated from the inner surface side to the outer surface side of the base, but the base inner terminal 3 is composed of two plates constituting the bottom surface portion of the base. It has a structure that is stopped at an interface between a certain base bottom surface configuration plate 1d (second base) and a base bottom surface configuration plate 1e (first base). A wiring pattern 10 is provided at this interface. The wiring pattern 10 is connected to the base inner terminal 3, extends horizontally and exposed to the outer surface, and is further connected to the connection terminal 4.

  The pad film 2 is formed by forming an aluminum film with a thickness of 5 μm to 100 μm in the same manner as described above. A pair of cell leads 8 connected to the cell 7 is connected to the pad film 2 by welding. In addition, after the electrolyte is filled, the base 1 and the lid 6 are hermetically sealed to form an exterior container.

  4B, at the interface of the lower ceramic plate 1e, the wiring pattern 10 made of a metal film such as tungsten connected to the terminal 3 in the base has a wide area as shown by hatching. Is provided. And it is pulled out horizontally by the edge part of the long side of the base bottom face structure board 1e of a ceramic board, and is extended to the side surface. The extension portion is connected to the connection electrode 4. Since such a solid wiring pattern is used, the resistance value of the wiring pattern can be kept low.

  On the other hand, in FIG. 4C, a straight wiring pattern 10a having a width d is extended outward from each point corresponding to the terminal 3 in the base. Thus, the wiring pattern is not limited to a solid shape. However, in this case, the resistance value of the wiring pattern 10a is higher than that in FIG. Therefore, it is necessary to determine the wiring pattern in consideration of the number of terminals in the base, the width d, the length (L1 and L2), and the sheet resistance value of the wiring pattern.

  An example of the wiring resistance value will be described below. For example, d, L1, and L2 are 0.2 mm, 3 mm, and 2 mm, respectively, and the sheet resistance value of the wiring pattern 10a is 10 mΩ. This value is a typical value of the sheet resistance value of a tungsten film having a thickness of about 10 μm. The resistance value of the wiring pattern in the length L1 portion is 10 mΩ × (3 mm / 0.2 mm) = 150 mΩ. The resistance value of the wiring pattern having a length of 2 mm is calculated as 100 mΩ by the same calculation. In the figure, since four wiring patterns are provided, the parallel resistance value of these four wiring patterns is calculated to be 30 mΩ. Since the same wiring pattern is used for both the positive electrode and the negative electrode, the approximate resistance value of this wiring pattern is estimated to be 60 mΩ.

  When the width d of the wiring pattern is further increased to 0.4 mm, the parallel resistance value of the four wiring patterns is calculated to be 15 mΩ by the same calculation. Therefore, when 0.2 mm is used as the value of d, Compared to half, it can be reduced. Similarly, if the value of d is 0.6 mm, the parallel resistance value of the wiring pattern is 10 mΩ, and if the value of d is increased to 0.8 mm, the parallel resistance value of the wiring pattern is 7.5 mΩ. Thus, it can be seen that a sufficiently low value can be realized by adjusting the value of d. However, the wiring resistance value of the exterior container is a total value of the wiring resistance value of the side region and the wiring resistance value of the connection terminal in addition to the resistance value of the wiring pattern.

  As shown in the present modification, the filling through electrode 3 does not have to have a structure that directly penetrates the upper side surface and the outer side surface of the base, and is combined with the wiring patterns 10 and 10a having appropriate resistance values. The present invention can be used for high current discharge purposes.

  Next, an example in which through regions are provided on the bottom and side walls of the base will be described with reference to FIG. FIG. 5A is a cross-sectional view of the electrochemical cell of this modification. FIG. 5B is a schematic diagram for explaining the base of this modification, and the lid connecting metal layer 5 is omitted. Further, the protective film 11 shown in FIG. The protective film 11 will be described later.

  A solid wiring pattern 10 functioning as a current collector is provided on the base inner surface 1a of the base 1, and a pad film 2 is provided thereon. The wiring pattern 10 is made of a refractory metal such as tungsten. Further, the wiring pattern 10 extends horizontally on the inner side surface of the base 1, penetrates between the bottom surface and the side wall of the base 1, is exposed to the side surface, and is further connected to the connection terminal 4 from the side surface of the base 1. ing. In FIG. 5A, the pad film 2 is provided on both the positive and negative electrodes, but may be formed on at least the wiring pattern 10 corresponding to the positive electrode.

  The cell lead 8 connected to the cell 7 is connected to the connection terminal via the pattern of the total length of the wiring pattern 10 of length L3 and L4 and the side surface portion (indicated by reference numeral 10b) of the wiring pattern of length L5. 4 is connected. Therefore, in the wiring resistance value, the total length of the wiring patterns 10 and 10b becomes a problem. Here, L4 is a length corresponding to the thickness of the side wall of the base. Below, the rough example of the wiring resistance value which the wiring patterns 10 and 10b have is shown.

  As numerical examples, the values of L3, L4, and L5 are 3.4 mm, 0.8 mm, and 0.5 mm, respectively. This dimension is a numerical value assuming a ceramic package made of a rectangular parallelepiped having a long side of 10 mm, a short side of 5 mm, and a height of 3 mm shown in Example 1 later. That is, the value of L4 is the thickness of the side wall, and the value of L5 is the thickness of the base bottom. In addition, the value of L3 is a value that is considered so that the two can be sufficiently separated in the vapor deposition method even if the two pad films of the positive electrode and the negative electrode are arranged side by side, and the added value with L4 is half of the long side A value that is smaller than the length but as close as possible is selected. The pattern portions (L3 and L5) of the tungsten film plated with nickel and gold as the two sheet resistance values are 5 mΩ, and 10 mΩ for L4 which is a tungsten-only film. Further, the width d2 of the wiring pattern is set to 3.0 mm. Here, the numerical value of d2 adopts a numerical value close to 3.4 mm (the short side of the inner bottom surface of the base), which is a value obtained by subtracting 1.6 mm of the thickness of the two side walls from the short side length of 5 mm, As shown, the wiring resistance value of the wiring pattern is suppressed.

  In the portion L3, if the wiring resistance value is calculated by the distance from the center, the length is 1.7 mm, which is half of the length, so the wiring resistance value is 5 mΩ × (1.7 mm / 3 mm) = 2. 83 mΩ, or 2.9 mΩ. From the same calculation, the L4 portion is 2.7 mΩ, the L5 portion corresponding to the side surface 10b is 0.9 mΩ, and the total value is about 6.5 mΩ. In the positive electrode, since a pad film made of aluminum is formed, the wiring resistance value of the L3 portion is further reduced from 2.9 mΩ.

  If the wiring resistance value is about 13 mΩ in total for the positive electrode and the negative electrode and the connection resistance value on one side of the electrode is 1 mΩ or less, as described in Table 2, a single electrochemical cell has a discharge current of 1.75 A. However, the initial voltage drop is 0.3V or less. Similarly, as shown in Table 3, since the wiring resistance value is smaller than 14 mΩ, the initial voltage drop is 0.3 V or less even at a discharge current of 0.90 A when two are connected in series. Further, according to Table 4, since the wiring resistance value is smaller than 14 mΩ, the initial voltage drop is 0.3 V or less at a discharge current of 0.60 A even when three series are connected. That is, this modification can be used for large current discharge applications.

  Next, the protective film 11 will be described. In the present modification, a protective film is provided as shown in FIG. 5C or FIG. 5D so that the inner surface side of the wiring pattern 10 functioning as a current collector does not contact the electrolyte. In FIG. 5C, the pad film 2 is formed to extend to the inner side surface 1f of the base side wall (indicated by reference numeral 2a). By forming the film up to the inner side surface of the base side wall, it is possible to prevent the pad film 2 near the boundary between the base inner side surface 1a and the side wall inner side surface 1f of the base from becoming thin. Therefore, in FIG. 5C, the portion 2a and the vicinity region of 2a are used as the protective film 11. As a result, the entire surface of the wiring pattern 10 can be covered with the pad film 2 having the appropriate thickness described above, and therefore, the electrolytic corrosion of the wiring pattern 10 can be prevented.

  In FIG. 5D, a film made of a material different from that of the pad film 2 is used as the protective film 11, and the inner surface side of the wiring pattern 10 is covered to prevent the wiring pattern 10 from coming into contact with the electrolyte. Here, the protective film 11 includes adhesion to the surface of the wiring pattern 10 and the base material, electrolyte resistance, electrolyte non-permeability, temperature characteristics when mounted on a substrate, ease of film formation and application, curing temperature, and the like. It is decided in consideration of Further, the protective film 11 is not limited to a single layer, and may be a multilayer film coated with a plurality of films. As the protective film 11, an inorganic coating material, butyl rubber, polyimide, polyamideimide-based heat-resistant resin, epoxy ultraviolet curable resin, or the like can be used. The curing temperature is about 100 ° C. for epoxy ultraviolet curable resins, about 120 to 150 ° C. for inorganic coating materials, and about 230 to 270 ° C. for polyamideimide and polyimide. Thus, the curing temperature of the protective film 11 is lower than the melting point of aluminum. Therefore, even if the protective film 11 is applied after the pad film 2 made of aluminum is formed, the pad film 2 is not affected.

  As described above, also in this modification, the wiring resistance value can be suppressed to a sufficiently low value. Further, since the wiring pattern 10 functioning as a current collector is not exposed to the electrolyte by the protective film 11, it can be stably used for the purpose of the large current discharge intended by the present invention.

  Subsequently, a further modification will be described with reference to FIG. The electrochemical cell shown in FIG. 6A includes a base 1 made of a ceramic flat plate and a metal lid 6a having a concave shape as an outer container, and shows a cross-sectional view. As in the above-described invention, the cell 7, the pair of cell leads 8, the pair of pad films 2, the base terminal 3 and the electrolyte are accommodated inside the container, and the cell leads 8 and the pad film 2 are welded. It is connected by.

  As shown in FIG. 6A, the lid 6 a is welded so that the opening is brought into contact with the bonding metal member 5 provided around the base 1 so as to cover the cell 7 and the like. For this welding, laser seam welding is preferred. Further, when performing seam welding, scanning irradiation is performed from the direction of the arrow in FIG. In resistance seam welding using a roller electrode, the roller electrode tends to come into contact with the step of the lid 6a, and it becomes difficult to make the roller electrode properly contact the joint.

  In the lid 6a, a small hole is provided in the bottom surface of the lid 6a. This is intended so that after the base 1 and the lid 6a are welded, the electrolyte can be filled from the small holes, and then hermetically sealed using the sealing plug 6b. Thereby, the efficiency fall of the sealing operation | work by the electrolyte existing between the metal layer 5 for base joining and the joint surface of the lid 6a can be prevented. The material and the range of the thickness of the pad film 2 formed on the inner surface of the base 1, the structure and number of the terminals in the base 3, and the means for joining the cell leads 8 and the pad film 2 are the same as described above, so that description is made. Omitted.

  The electrochemical cell shown in FIG. 6 (b) has the same configuration as that of FIG. 6 (a), but the joining metal member 5 arranged around the flat base 1 is fitted into the step provided on the base. Therefore, the difference in height between the bonding metal member 5 and the inner side surface of the base is sufficiently small. Thereby, even if the cell 7 is arranged in the lid 6a after filling the electrolyte with the lid 6a turned upside down, the electrolytic mass overflowing from the lid 6a can be reduced. Therefore, with the configuration shown in FIG. 6B, the base 1 and the lid 6a can be easily welded even when the electrolyte is filled. Therefore, the small hole of the lid 6a as shown in FIG. 6A is unnecessary, and the sealing step by the sealing plug 6b can be omitted.

  Next, another modification will be described with reference to FIG. FIG. 7A shows a base used in this modification. In this modification, the base 1 is composed of a ceramic flat plate and a metal cylindrical side surface 12 joined to the flat plate, thereby forming a concave container. The base inner side surface 1a is provided with base inner terminals 3 that directly penetrate the outer side surface of the base, and a pair of pad films 2 are disposed thereon. The metal metal side wall 12 is selected so that the thermal expansion coefficient matches the flat plate of the base, and is bonded to the flat plate with a brazing material. On the other hand, the opening on the opposite side forms a joint surface of the lid 6. In this modification, the joining metal member 5 for sealing the lid 6 is not necessary, and the metal side wall 12 itself also plays the role of the joining metal member 5. Therefore, at least the surface to be joined to the lid 6 is provided with a nickel and gold plating film, and the lid 6 is brought into contact with the plated surface and can be joined by resistance seam welding or laser seam welding. It is configured as follows.

  FIG.7 (b) shows sectional drawing of the electrochemical cell using a base. A pair of cell leads 8 connected to the cell 7 are connected to the pad film 2 by welding means, and connected to the connection terminal 4 by the terminal 3 in the base. The container is filled with an electrolyte (not shown) and hermetically sealed with a lid 6. The material and thickness of the pad film are the same as described above. Since the metal side wall 12 is made of metal, it can be processed into various shapes. As the shape, a corner, a track shape, an ellipse, a circle, or the like can be selected. Particularly, when a standard hollow pipe is cut and used with an arbitrary length, the height of the electrochemical cell can be determined freely, and the manufacturing cost can be reduced.

  In the electrochemical cell shown in FIG. 7C, the metal side wall 12 made of metal is used as in FIG. 7B, but the pad film 2 is an example limited to only the positive electrode side. The positive lead 8b is connected to the pad film 2, while the negative cell lead 8c is connected to the inside of the metal side wall 12 by welding. Further, the connection terminal 4 corresponding to the negative electrode is configured to be electrically connected to the metal side wall. Thereby, since the metal side wall 12 is made of metal and a path through which a current flows is large, the wiring resistance value on the negative electrode side can be kept low. Therefore, the electrochemical cell of the present invention can also discharge a large current.

  Next, still another modification will be described with reference to FIG. FIG. 8 shows a cross section of the electrochemical cell. On the inner bottom surface 1a of the concave container 1 made of ceramic, a pad film 2 made of an aluminum film is provided in the same manner as described above. 4 is connected. In this modification, only one pad film is provided, and the positive electrode side 8b of the pair of cell leads 8 connected to the cell 7 configured by a winding method or a lamination method is connected to the pad film by ultrasonic welding. Thus, a sufficiently low connection resistance value is realized.

  On the other hand, the cell lead 8 c on the negative electrode side has a structure connected to the inner surface side of the lid 6. Even if the material of the cell lead 8c on the negative electrode side is made of a thin plate or foil of aluminum, copper, or nickel, the metal lid 6 is well-known such as ultrasonic welding, laser spot welding, resistance spot welding, arc welding, etc. It is possible to connect by the welding method. Therefore, the connection resistance value can be kept sufficiently low also on the negative electrode side.

  The connection terminal on the negative electrode side extends from the container bottom surface 1 b along the side surface to the bonding metal member 5 and is electrically connected to the lid 6. The extended part was made into the extended part 4b. By adjusting the length, width, and thickness of the conductor of the extended portion 4b, the DC resistance value of the extended portion can be kept low, so that the wiring resistance value on the negative electrode side can be configured without greatly increasing.

  The container 1 is filled with an electrolyte (not shown), and the lid 6 is welded to the joining metal member 5 to form an airtight container. In a lithium ion secondary battery, a copper foil is commonly used as a negative electrode current collector material, and a nickel thin plate is commonly used as a cell lead. However, this modification can be applied. Therefore, a highly reliable small and thin lithium ion secondary battery having high airtightness can be manufactured.

  In this modification, the extending portion is provided outside the container. The connection between the lid 6 and the connection terminal 4 is not limited to this, and a structure in which a hole is provided in the lower portion of the bonding metal member 5 and a conductor material is formed on the inner surface to connect to the connection terminal 4 is easy.

Example 1
Next, Example 1 will be described with reference to the manufacturing flow of the electric double layer capacitor shown in FIG. First, a base 1 having a concave shape shown in FIGS. 1A and 1B and a lid 6 were prepared as exterior containers. The base 1 has a long side of 10 mm, a short side of 5 mm, and a height of 2.85 mm, and the base 1 has a bottom thickness of 0.5 mm. As a material, a standard material used for manufacturing an electronic component package with ceramics was used. The bending strength of the material is 400 MPa and the Young's modulus is 310 GPa. The region where the pad film 2 is formed is filled with tungsten and the surface thereof is plated with nickel and gold, and the base inner terminal 3 having an inner diameter of 0.2 mm is directly penetrated through the inner side surface and the outer side surface of the base. Four each were provided. A pair of connection terminals 4 are arranged on the base outer surface 1 b and are connected to the base inner terminals 3. The connection terminal is gold-plated with nickel as a base (S10).

Next, a pair of pad films 2 made of an aluminum vapor deposition film was formed on the base inner surface 1a. The dimensions of the pad film 2 are a long side of 2.4 mm, a short side of 2 mm, and a thickness of about 25 μm (S11).
On the other hand, for the lid 6, a Kovar plate having a thickness of 0.15 mm was prepared, and the surface was subjected to electrolytic nickel plating (S20).

  Subsequently, the cell 7 is prepared. A metal current collector made of aluminum having a thickness of 20 μm was coated with an active material made of activated carbon, a conductive auxiliary material, a binder and a thickener by a coating method to obtain a sheet electrode (S30). After cutting to an appropriate length, an aluminum thin plate having a thickness of 80 μm, a width of 2 mm, and a length of 8 mm was attached to one end of the metal current collector by ultrasonic welding to form a cell lead 8 (S31). A separator made of polytetrafluoroethylene was sandwiched between a pair of positive and negative sheet-like electrodes to which the cell leads 8 were welded, and then a core was inserted and wound into a track shape. Thereafter, the winding core was taken out and the gap was lightly crushed to obtain a wound electrode (S32).

  Subsequently, ultrasonic welding is performed. The cell lead 8 was brought into close contact with the surface of the pad film 2 of the base 1 prepared previously and positioned. The ultrasonic welding was performed for each cell lead (S33). The oscillation frequency of the ultrasonic melter was 40 KHz. The welding horn is made of iron, and an ultrasonic welding tip 9 made of the same material is integrally provided at the tip of the horn. On the surface of the ultrasonic welding tip 9, a 0.2 mm pitch staggered concavo-convex pattern (Nar) was provided in a 2 × 1.5 mm region. The difference between the height of the mountain and the bottom of the valley is 0.2 mm. The welding mode was a mode for controlling the energy supplied to the cell lead 8 during welding, the welding energy set value was 15 J, and the maximum welding time was 60 msec. After the ultrasonic welding tip 9 is lowered onto the surface of the cell lead 8 made of aluminum by the air mechanism, the ultrasonic welding tip 9 bites into the surface of the cell lead 8 and vibrates between the interface between the cell lead 8 and the pad film 2 to perform welding. .

  After welding, the cell 7 was stored in the base 1 so that the cell lead 8 was folded. At this time, attention was paid so that the cell lead 8 would not come into contact with the bonding metal member 5 (S34). This is to avoid a short circuit of the cell.

  Next, the base 1 in which the cells 7 were stored was immersed in a liquid electrolyte and vacuum degassed for 1 hour. Here, the supporting salt of the electrolyte was spirobipyrrolidinium tetrafluoroborate, and a mixed solution of polycarbonate and ethylene carbonate was used as a non-aqueous solvent (S35). Subsequently, after returning to atmospheric pressure and taking out the base 1 containing the cells 7 from the electrolyte, the lid 6 is brought into contact with the joining metal member 5 in a nitrogen atmosphere, and temporary welding at two points on the long side is performed. Subsequently, resistance seam welding was continuously performed on the long side and the short side in this order, and hermetically sealed (S36). Thus, the electric double layer capacitor of Example 1 was produced.

  The electrical characteristic inspection of the produced electric double layer capacitor of Example 1 was performed (S37). Items were measured for equivalent series resistance and capacitance. For the equivalent series resistance, an AC resistance method at AC 1 KHz was used. Moreover, the capacity | capacitance used the discharge method (The measurement current was 10 mA between 2V-1V).

(Comparative Example 1)
A cell 7 was produced using a sheet electrode having the same dimensions as in Example 1. Here, the material, width, and thickness of the cell lead were the same as in Example 1, but the length was 40 mm. Next, the same electrolyte was filled and stored in an outer container made of an aluminum laminate film. In this way, an electric double layer capacitor using the aluminum laminate package of the comparative example was produced. Since this comparative example 1 does not have a pad film, the connection resistance shows a practical value.

About the produced electrical double layer capacitor of Comparative Example 1, the electrical property inspection was performed in the same manner as in Example 1.
The equivalent series resistance of Example 1 was 310 mΩ. The capacity was 170 mF. The measured value of equivalent series resistance of Comparative Example 1 was 320 mΩ. Further, the capacity was 180 mF which is substantially the same as that of Example 1. That is, it can be seen that the wiring resistance value can be suppressed to a practical level by welding the pad film and the cell lead. Table 5 shows a comparison of the resistance of the outer container including the resistance value of the cell lead 8 among the equivalent series resistance values of Example 1 and Comparative Example 1.

  In Table 5, the numerical value of 2.4 mΩ in the connection resistance value column is the sum of the connection resistance value between the R1 cell lead 8 and the pad film 2 and the following three wiring resistance values. The three wiring resistance values are the resistance value of the R2 pad film 2 itself, the resistance value of the R3 base inner terminal 3, and the resistance value of the R4 connection terminal 4. R1, R2, R3, and R4 are shown in FIG. The 2.4 mΩ shown in the connection resistance value or the like is a value obtained by actually preparing a measurement sample separately. Since six charging through holes 3 are arranged for one pad film 2 as described above, the resistance value R3 of the charging through hole 3 is a resistance value contributed by these six through holes. ing. The values of this connection resistance and the like are set to 0 mΩ because the cell lead is exposed outside the package as it is and connected to the measuring terminal of the measuring instrument in the aluminum laminate package of the comparative example. All numerical values are the sum of the positive electrode and the negative electrode.

  Since the numerical values such as the connection resistance values in Table 5 are 1.2 mΩ for the electrode on only one side and 2.4 mΩ for both electrodes, it can be seen that the numerical values from R1 to R4 are sufficiently low in this embodiment. . The connection resistance value between the cell lead and the pad film is calculated to be 1 mΩ or less when the resistivity of the deposited aluminum film constituting the pad film is 6.6 μΩcm from a number of separate experiments. Since the deposited film of aluminum is usually about 2.2 to 2.7 times the bulk value (2.75 μΩcm), 6.6 μΩcm is equivalent to 2.4 times and seems to be reasonable. It is.

  Further, the structure in which the six base terminals 3 are directly connected to the connection terminals 4 also suppresses the wiring resistance value composed of the sum of R1, R2 and R3 sufficiently low. Therefore, in the column of the total value in Table 5, the total of Example 1 is 5.2 mΩ, which is a value equivalent to 13.6 mΩ, which is the total value of the aluminum laminate package.

(Comparative Example 2)
For the purpose of comparing the above connection resistance value with the connection resistance value in the case of connecting means using a conductive adhesive, the same base 1 and aluminum thin plate as in Example 1 were connected using a conductive adhesive. The connection resistance value was obtained. The main conductive fillers of the conductive adhesive are graphite and carbon. Table 6 shows the results.

The conductive adhesives D1 and D2 are commonly used when an electrode made by kneading activated carbon, carbon, and polytetrafluoroethylene powder to form a sheet is bonded to aluminum or stainless steel. D3 is a conductive paint, which can be applied to aluminum stainless steel with excellent wettability. The connection area was about 4 mm ² and the curing temperature was 150 ° C. for 30 minutes.

The connection resistance value was 9.4Ω even when D3 was used, and the value of D1 and D2 exceeded 10Ω. Such a value causes a significant voltage drop due to charging / discharging, and thus is not suitable for the large current discharge intended by the present invention. Since the connection resistance value of Example 1 was 1 mΩ or less as described above, a numerical value as low as 3 digits compared to the case of Comparative Example 2 was achieved. Table 6 shows the connection resistance value converted per unit area (1 cm ² ), but it is 300 mΩ or more even when the connection area is expanded to 1 cm ² , which is too large for the connection resistance value. . Connection using a conductive adhesive is unsuitable for an electrochemical cell using a small outer container which is the object of the present invention. That is, the electrochemical cell according to the present invention in which the cell lead and the pad film are connected by welding is extremely low in comparison with the electrochemical cell in which the cell lead and the pad film are connected by using the conventional conductive adhesive. It turns out that it becomes.

  Then, the influence of the heat | fever in the reflow process of the sample created in Example 1 was examined. This sample was subjected to a reflow treatment with a reflow apparatus to which a maximum temperature of 270 ° C. was applied for several seconds, and then the outer appearance of the outer container was closely observed with an optical microscope. No cracks were observed in the base 1. In addition to the resistance seam weld between the base 1 and the lid 6, there was no electrolyte leakage near the through-electrode opening on the lower side of the base.

  Furthermore, the same member was welded separately under the condition of ultrasonic welding of the cell lead 8 and the pad film 2, and the cross section of the joint interface was observed with an optical microscope. A sample in which the cell lead 8 and the pad film 2 were ultrasonically welded was embedded in a resin and solidified, and then gradually polished from one direction and closely observed. As a result, it was observed that the unevenness of the ultrasonic welding tip was transferred to the cross section of the cell lead 8, and the vicinity where the convex portion of the tip was cut in was joined to the aluminum film forming the pad film. Further, in the vicinity of the contact with the concave portion of the chip, a gap of several μm was observed from the aluminum film pad. That is, the cell lead 8 and the pad film 2 were joined at a joining point corresponding to the unevenness of the ultrasonic welding tip. In the cross section of the ceramic corresponding to the lower surface of the pad film 2, no cracks were observed including the vicinity where the base terminal 3 was formed.

  As described above, a structure in which the wiring resistance value is kept low by arranging the terminal in the base that is directly connected from the inner surface to the outer surface of the base, and the cell lead 8 and the pad film 2 are connected by ultrasonic welding. The resistance value is sufficiently low, and it has become possible to realize an electrochemical device for large current discharge. Then, by setting appropriate welding conditions, welding can be performed without damaging the base, so that an electrochemical cell having excellent reliability can be manufactured.

(Example 2)
The step of joining the cell lead 8 and the pad film 2 was performed by spot welding with a YAG laser. Nitrogen was blown to prevent oxidation at the joint during welding.
The aluminum thin plate has a thickness of 80 μm and a width of 2 mm (the same as that used for the cell lead 8 in Example 1). Unlike the first embodiment, the ceramic-made concave container has the same structure as the structure shown in FIG. 4C described in the second modification, and has six base inner terminals penetrating partway through the base. . The thickness of the bottom surface of the base is 0.3 mm, which is thinner than that of Example 1, and aluminum is formed on the inner side surface of the base with a thickness of about 25 μm by vapor deposition. The dimension of the pad film is a rectangular shape of 3 mm × 1.3 mm.

  Welding was performed as follows. First, the cell lead 8 was sufficiently adhered to the aluminum film. Subsequently, the positions of the four corners of the tip of the lead 8 were mechanically pressed so as to maintain close contact, and then two spots were spot welded with a YAG laser. Here, the welding conditions are such that the peak output is 300 W and the pulse width is 1 msec, that is, the energy of one pulse is 0.3 J.

  Thus, the total value of the wiring resistance value and the connection resistance value of the sample to which the cell lead was connected was measured. The measurement was performed by soldering a thin copper lead to the bottom of the base and then measuring the distance between the cell lead and the copper lead using the resistance meter described above. The resistance value obtained by subtracting the wiring resistance value of the cell lead and the copper lead from the total value (the sum of the connection resistance value and the base wiring resistance value) was in the range of about 38 to 40 mΩ. When the same sample was welded using the same ultrasonic welding apparatus as in Example 1 (however, the ultrasonic welding tip 9 was replaced and the welding area was welded in an area of 2.0 × 0.5 mm). The resistance value (the sum of the connection resistance value and the base wiring resistance value) was also in the same range. Thereby, it is estimated that the connection resistance value at the time of laser welding is substantially the same as that at the time of ultrasonic welding.

  Separately from this sample, a cross-sectional observation of a laser welded portion under the same welding conditions was performed. According to the cross-sectional observation by the optical microscope, the connection part of the aluminum cell lead 8 and the pad film 2 made of the lower aluminum vapor deposition film was connected in a region having a diameter of about 120 μm. Moreover, no damage such as cracks was observed in the ceramic around the connection area. Thereby, a method using a laser as a welding means is also possible.

(Example 3)
In both Examples 1 and 2, the base material was ceramic. In this embodiment, the case where the base material is glass will be described. An aluminum film was formed on the surface (one side) of soda lime glass (thickness: about 1.3 mm) by ion plating. The thickness was 5 μm. An aluminum thin plate having the thickness of 80 μm and the width of 2 mm (the same as that used for the cell lead 8 in Example 1) was welded to the aluminum surface by ultrasonic welding. In the ultrasonic welding, the oscillation frequency was 62.5 KHz. The area of the tip of the ultrasonic welding tip has a long side of 2 mm and a short side of 0.5 mm, and staggered irregularities are processed on the surface of the tip.

  Under this welding condition, the aluminum thin plate was reliably welded to the aluminum film, and no crack was induced in the soda lime glass. After measuring the total value of the wiring resistance value and the connection resistance value between the two aluminum thin plates by ultrasonic welding, the wiring resistance value was subtracted to calculate the connection resistance value. At this time, when the resistivity of the aluminum film formed by ion plating was 3.8 μΩcm, the connection resistance value was calculated to be 1 mΩ or less.

  Therefore, the base material is not limited to ceramics, and may be a brittle material such as soda lime glass. Since the technology for forming the terminal in the base on soda-lime glass or heat-resistant glass is known as described above, it can be used as a base material for electrochemical cells for large current applications by combining with the pad film of the present invention. is there.

Example 4
The ceramic material used in this example has a bending strength of 350 MPa and a Young's modulus of 280 GPa, and is a standard electronic component package. A sample was prepared in which a large number of terminals in the base having an inner diameter of 0.3 mm were provided in a XY direction at a pitch of 0.5 mm on a plate made of ceramics having a thickness of 0.3 mm. A solid tungsten pattern was provided on the opening surface of the base inner terminal on both the front and back surfaces so as to connect the base inner terminals to each other. The thickness of tungsten is 10 μm, and the surface is plated with nickel and gold. As a cell lead, a thin aluminum plate having a thickness of 80 μm and a width of 2 mm was positioned on the surface of the plated tungsten and welded by ultrasonic welding. The ultrasonic welder and the ultrasonic welding tip are the same as those in Example 3.

  The weld cross section of the sample welded under the above welding conditions was observed in the same manner as in Example 1. Although the vicinity of the openings of a large number of through holes arranged was carefully observed with an optical microscope, no cracks were observed in the ceramic. That is, the same welding means for the positive electrode can be applied to the negative electrode current collector side even if the aluminum pad film is not provided. Thereby, it is not necessary to prepare separate welding means for the positive electrode and the negative electrode, which is advantageous in production.

In order to function stably as an electrochemical cell, as described above, the current collector for the positive electrode formed on the inner surface of the base needs to be coated with a valve metal such as aluminum. Not required for current collectors. The above-described aluminum pad film may be provided at least on the positive electrode current collector. At this time, the current collector for the negative electrode is formed of a tungsten film used for forming the terminal in the base and having a surface plated with nickel and gold.
If the above-described welding for connecting the cell lead 8 and the pad film 2 can be applied to the connection of the other cell lead 8 and the tungsten film, it is advantageous in manufacturing.

(Example 5)
The cell leads 8 shown in Examples 1 to 4 described above were all aluminum. In Example 5, the cell lead 8 is made of nickel. Nickel leads are commonly used as negative electrode leads for lithium ion secondary batteries. For example, after the nickel lead is connected to the negative electrode current collector made of copper foil, the other end is connected to the pad film inside the exterior container.

  A pad film was formed by vapor-depositing 5 μm thick aluminum on a 0.5 mm thick ceramic plate made of the same material as in Example 1. Nickel leads having a width of 6 mm and a thickness of 100 μm were placed and ultrasonic welding was performed. On the surface of the ultrasonic welding tip, an irregular pattern of a staggered lattice having a pitch of 0.7 mm was provided in an area of 4 mm × 3 mm. The difference between the mountain and the valley bottom is 0.30 mm. This chip was pressed against the surface of the nickel lead. The welding mode was a method of specifying the welding time, and the constant welding time was 0.15 seconds. Welding with sufficient welding strength was possible under the conditions of air pressure of 0.1 MPa, welding energy of 22.1 joules, and welding amplitude of about 13 μm.

The bonded member was embedded in the resin as described above and then polished, and the cross section of the bonded portion was observed. Although detailed observation was performed, there was no crack in the ceramic part. Therefore, even when a nickel lead is used as the cell lead, an electrochemical cell having the structure of the present invention can be configured.
In addition, it is desirable to coat the pad film made of aluminum to which the nickel lead is connected for the negative electrode of the lithium ion secondary battery with an insulating paint so as not to be exposed to the electrolytic solution.

(Example 6)
In this embodiment, the cell lead 8 is a copper foil. The same ceramic plate as in Example 5 was prepared. Five copper foils each having a width of 6 mm and a thickness of 20 μm were stacked on an aluminum pad film formed to a thickness of 5 μm. The same ultrasonic welding tip as in Example 5 was used. An ultrasonic welding tip was pressed against the surface of the copper foil for welding. The welding conditions were the same as in Example 5. That is, the welding mode is a method of specifying the welding time, the constant welding time is 0.15 seconds, the air pressure is 0.1 MPa, the welding energy is 22.1 joules, and the welding amplitude is about 13 μm. Under these conditions, welding with sufficient welding strength was possible, and the copper foil was not peeled off.

  The bonded member was embedded in the resin as described above and then polished, and the cross section of the bonded portion was observed. Although detailed observation was performed, there was no crack in the ceramic part. Therefore, even when a copper foil lead is used as the cell lead, an electrochemical cell having the structure of the present invention can be configured.

  When the copper foil is a current collector for a negative electrode of a lithium ion secondary battery, the pad film made of aluminum to which the copper foil is connected is covered with an insulating paint so as not to be exposed to the electrolytic solution. Is desirable.

  The present invention is not limited to the modifications and examples described in the present specification, and various other configurations can be taken without departing from the gist of the invention. For example, unless limited in the claims, the lid is not limited to metal, and ceramic, glass, resin, or the like can be used, and various sealing means are possible depending on the material.

  The electrochemical cell shown in FIGS. 6 and 7 is not limited to the bottom surface of the base being attached to the substrate horizontally, and the mounting direction may be determined according to the dimensions of the electrochemical cell. For example, when the height dimension of the lid 6a is large, the electrochemical cell can be mounted horizontally on the substrate. For this purpose, the connection terminal pattern provided on the base can be slightly changed.

DESCRIPTION OF SYMBOLS 1 Base 1a Base inner surface 1b Base outer surface 1c Base side surface 1d Base bottom surface configuration plate 1e Base bottom surface configuration plate 1f Base side wall inner surface 2 Pad film 3 Base inner terminal 4 Connection terminal 4b Extension part 5 Bonding metal member 6 Lid 6a Cavity Mold lid 6b Seal plug 7 Cell 8 Cell lead 8a Cell lead and pad membrane welding area 8b Positive cell lead 8c Negative cell lead 9 Ultrasonic welding tip 9a Tip tip 10, 10a, 10b Wiring pattern 11 Protective film 12 Metal side wall

Claims (21)

An electrochemical cell composed of an outer container made of a base and a lid, a cell housed in the outer container, and an electrolyte,
A plurality of cell leads that are extensions of the cell;
A pad film made of a valve metal formed on the inner surface of the base;
A connection terminal provided on an outer surface of the base and electrically connected to the pad film;
An electrochemical cell, wherein at least one of the cell leads is connected to the pad film by welding.   The electrochemical cell according to claim 1, wherein the pad film has a thickness of 5 μm to 100 μm.   The electrochemical cell according to claim 1, wherein the pad film has a thickness of 10 μm to 30 μm.   The electrochemical cell according to any one of claims 1 to 3, wherein the pad film contains aluminum.   The electrochemical cell according to any one of claims 1 to 4, wherein the welding is ultrasonic welding or beam welding.   The electrochemical cell according to any one of claims 1 to 5, wherein the base is made of ceramic or glass.   The electrochemical cell according to any one of claims 1 to 6, wherein the cell lead is made of aluminum, nickel, or copper.   8. The electrochemical cell according to claim 1, wherein, of the cell leads, both of the positive and negative cell leads are welded to the pad film. 9.   The electrochemical cell according to any one of claims 1 to 7, wherein the cell lead of the negative electrode is electrically connected to the lid.   The electrochemical cell according to any one of claims 1 to 9, wherein the pad film and the connection terminal are connected via an in-base terminal embedded in the base.   11. The electricity according to claim 1, wherein the outer container is formed by sealing the concave base and the plate-shaped lid directly or via a bonding metal member. Chemical cell. The base is composed of a first base that is an outer layer of the outer container and a second base that is an inner layer,
The base inner terminal penetrates the second base,
The electrochemical cell according to claim 10, wherein the connection terminal extends from an outer surface of the base to a boundary surface between the first base and the second base, and is connected to the terminal in the base.   The electrochemical cell according to any one of claims 1 to 9, wherein the pad film is connected to the connection terminal via a wiring pattern extending on an inner surface of the base. .   The electrochemical cell according to claim 13, wherein the wiring pattern is covered with a protective film so as not to be exposed to the electrolyte.   The electrochemical cell according to any one of claims 1 to 11, wherein the base has a flat plate shape, and the lid has a concave shape.   16. The electrochemical cell according to claim 15, wherein the base or the lid has a small hole, and the small hole is sealed with a sealing plug.   The electrochemical cell according to claim 15 or 16, wherein the base member has a step on a surface in contact with the bonding member, and the bonding member is fitted in the step.   The electrochemical cell according to any one of claims 1 to 8, wherein the base member and the lid have a flat plate shape and are sealed through a metal side wall.   The electrochemical cell according to claim 18, wherein the cell lead of the positive electrode is connected to the metal side wall. A pad film forming step of forming a pad film on the inner surface of the base constituting the exterior container;
A cell lead / pad film welding process for connecting the cell lead and the pad film by welding;
Storing the cell in the base;
Filling the electrolyte; and
And a step of bonding the lid to the base.   21. The method of manufacturing an electrochemical cell according to claim 20, wherein the welding process between the cell lead and the pad film uses ultrasonic welding or beam welding.

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