JP6513773B2 - Electrochemical cell - Google Patents

Description

  The present invention relates to an electrochemical cell.

  Electrochemical cells are conventionally used as backup power supplies for clock functions, backup power supplies for semiconductor memories, power supplies for electronic devices such as microcomputers and IC memories, power supplies for batteries and motors for solar clocks, etc. Is being considered as a power source for electric vehicles and as an auxiliary storage unit for energy conversion and storage systems.

  Further, since the conventional electrochemical cell has a round shape such as a coin or a button, it is necessary to previously weld a terminal or the like to the case in order to perform reflow soldering, which increases the number of parts and the number of manufacturing steps. In terms of that, the cost has been increased. In addition, it is necessary to provide a terminal space on the substrate, which limits the miniaturization.

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

JP 2001-216952 A

  The electrochemical cell according to the above configuration is suitable for memory backup applications, and the discharge current of the electrochemical cell is in the range of several μA to several mA at most. However, for electrochemical cell applications, it discharges a current of several hundred mA to several A 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 New applications such as intermittent drive have come out (hereinafter referred to as high current discharge applications). In the electrochemical cell according to the above configuration, the connection resistance value may reach a level of several ohms, causing 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 high 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 case comprising a base and a lid, a cell housed in the outer case, and an electrolyte, wherein an inner surface of the base is made of aluminum. And at least one pad film connected by welding to a cell lead which is an extension of the cell is formed , a connection terminal is provided on the outer surface of the base, and the connection terminal and the pad film are made of high melting point metal connects electrical manner through the base in the terminal comprising a further said pad film is an electrochemical cell, characterized by being covered with an insulating coating.

According to the invention as set forth in claim 1, by connecting the cell lead and the pad film by welding, an electrochemical cell is realized which realizes a significantly lower connection resistance value as compared with the conventional method using a conductive adhesive. it can.
Further, by providing at least one conductive in-base terminal in the base, the wiring pattern can be shortened, and therefore, the wiring resistance value can be reduced.
Further, by connecting the pad film and the connection terminal through the in-base terminal, the length between the pad film and the connection terminal can be sufficiently shortened. Therefore, the wiring resistance can be suppressed sufficiently low. Further, even if the size of the outer container is increased, the increase in the wiring resistance can be suppressed.
Furthermore, the pad film is made of aluminum. Thus, the pad film can be made soft and easy to weld. In addition, the low electrical resistivity of aluminum itself can reduce the connection resistance by welding. Moreover, it becomes a chemically stable pad film by being covered with an insulating paint so that it may be made of aluminum and not exposed to the electrolytic solution.
Therefore, stable large current discharge is possible over a long period of time.

The invention according to claim 2 is an electrochemical cell comprising an outer case comprising a base and a lid, a cell housed in the outer case, and an electrolyte, wherein an inner surface of the base is made of aluminum. And at least one pad film connected by welding to a cell lead which is an extension of the cell is formed, a connection terminal is provided on the outer surface of the base, and the connection terminal and the pad film are made of high melting point metal And an inner surface side of the base of the in-base terminal is covered with a protective film of a material different from that of the pad film. It is a cell.

According to the invention as set forth in claim 2, by connecting the cell lead and the pad film by welding, an electrochemical cell is realized which realizes a significantly lower connection resistance value as compared with the conventional method using a conductive adhesive. it can.
Further, by providing at least one conductive in-base terminal in the base, the wiring pattern can be shortened, and therefore, the wiring resistance value can be reduced.
Further, by connecting the pad film and the connection terminal through the in-base terminal, the length between the pad film and the connection terminal can be sufficiently shortened. Therefore, the wiring resistance can be suppressed sufficiently low. Further, even if the size of the outer container is increased, the increase in the wiring resistance can be suppressed.
Furthermore, the pad film is made of aluminum. Thus, the pad film can be made soft and easy to weld. In addition, the low electrical resistivity of aluminum itself can reduce the connection resistance by welding. Moreover, it becomes a chemically stable pad film by being made of aluminum.
Further, the wiring pattern can be prevented from being exposed to the electrolyte by covering with a protective film of a material different from the pad film.
Therefore, stable large current discharge is possible over a long period of time .

The invention according to claim 3, of the cell read, an electrochemical cell according to claim 1 or 2, characterized in that with the cell read the positive and negative electrodes are electrically connected to the pad layer.

The invention according to claim 4 is characterized in that, among the cell leads, the cell lead of the positive electrode is electrically connected to the pad film, and the cell lead of the negative electrode is electrically connected to the lid. It is an electrochemical cell as described in any one of 1 to 3 .

According to the invention of claim 4 , it is possible to suppress the connection resistance value sufficiently low.

The invention according to claim 5 is characterized in that the exterior container is one in which the base and the lid are sealed via a bonding metal member, according to any one of claims 1 to 4. Electrochemical cell.

According to the invention of claim 5 , it is possible to suppress the connection resistance value sufficiently low.

  According to the present invention, the cell lead and the pad film are connected by welding, thereby achieving a significantly lower connection resistance value as compared with the conventional method using a conductive adhesive, and enabling a large current discharge. 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 between the pad film | membrane of the electrochemical cell of this invention, an in-base terminal, and a connection terminal. It is a figure explaining welding of the cell lead and pad film | membrane 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 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 the present invention will be described based on the drawings. The electrochemical cell of the present invention is mainly mounted and used on a substrate inside a personal computer or a small portable device. FIG. 1 (a) is an external view of the electrochemical cell of the present invention. As an example, although it is shown by the shape of a rectangular parallelepiped, it may be a track shape or a cylindrical shape. The electrochemical cell of the present invention is provided with a base 1 which functions as a container by accommodating the cell which is the power generation element and a lid 6 which functions as a sealing plate for sealing the opening airtightly as exterior components. The outer container of the electrochemical cell of the present invention is sealed by the base 1 and the lid 6.

  FIG.1 (b) is a figure which shows AA cross section of (a). A cell 7 is housed in a concave base 1 and 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. There is. In the cell 7, a pair of electrode sheets made of an active material and a current collector (hereinafter referred to as a metal current collector) made of a metal that supports the active material insert an insulating separator, and winding method, lamination method, etc. It is composed of At the end of the metal current collectors of the positive and negative electrodes, an extension was made by mechanically connecting an extension of the metal current collector itself and another thin, thin plate or wire-like lead. In the present invention, this is represented by the cell lead 8. The cell leads 8 of the positive electrode and the negative electrode are connected by welding to the pad films 2 which are a pair of current collector metal films disposed in parallel to the base inner side surface 1 a of the concave base 1. The bottom surface of the pad film 2 is provided with a hole which penetrates and connects the inner surface 1a of the base and the outer surface 1b of the base substantially perpendicularly. The holes are filled with a refractory metal such as tungsten to fill the air-tightness. In the present invention, the in-base terminal 3 means a terminal embedded inside the base, in addition to a conductive through hole filled with metal inside, a metal film is formed on the inner surface of the through hole to make it conductive. The inside is filled with an insulator such as glass to ensure that it is airtight. The in-base terminal 3 electrically connects the pad film 2 and the connection terminal 4 formed on the base outer surface 1 b. Then, 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 the present invention is described 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 2.6 V and the capacitance is 1F. The value of the equivalent series resistance is the sum A of the ion diffusion resistance value of the cell and the electron resistance value, the wiring resistance value of the outer container containing the cell, and the connection resistance value of the cell lead and the pad film (this wiring resistance value and connection The discharge characteristics of the electric double layer capacitor are evaluated by separating the sum of resistance values into B).

  Table 1 sets the value of A of the above equivalent series resistance to 50 mΩ and sets B to three ways (cases 1 to 3), and the voltage drop of the electric double layer capacitor when the pulse-like discharge current flows It is calculated. The current was 1 A, and the discharge pulse width was 1000 msec (1 second).

  Here, Case 1 was designed to have a value of B, that is, the wiring resistance value of the outer container and the connection resistance value between the cell lead and the pad film sufficiently small, and was 20 mΩ. The total value of the equivalent series resistance is the sum of A and B, which is 70 mΩ. Since the discharge current is 1 A, the voltage drop generated by the equivalent series resistance is the product of the current and the equivalent series resistance, that is, 1A × 0.07 Ω = 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, the current of 1 A is discharged for 1000 msec, which results in 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 to 2.6 V, at the end of this discharge, the electric double layer capacitor maintains a voltage of 2.6-1.07 = 1.53 V become. That is, in Case 1, it can be said that a high current discharge application of 1000 msec can be realized at 1A.

  Cases 2 and 3 in Table 1 are also calculated in the same manner. Case 3 assumes an electric double layer capacitor in which a cell lead and a pad film are connected by a connection means such as a conventional conductive adhesive, and the value of B is 2000 mΩ, and the total equivalent series resistance is Reaches 2050 mΩ. Therefore, the voltage drop due to the equivalent series resistance alone is 2.05 V, and adding the voltage drop of 1 V to which the capacity contributes contributes 3.05 V, exceeding the initial rated voltage. That is, the electric double layer capacitor can not discharge in the middle of the pulse width of 1000 msec, and a large current discharge can not be realized.

  Case 2 corresponds to the middle of 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 finished with 0.55V. Therefore, even if including the voltage drop of the contribution of capacity, the total value of voltage drop remains at 1.55V and the rated voltage is 2.6V or less, so a large current discharge of 1000msec can be realized at 1A. is there.

  As described above, in three cases, it was shown whether or not large current discharge was possible. Although large current discharges were possible in Case 1 and Case 2 where the value of B is low, it should be noted that the contribution of the voltage drop due to the value of B is proportional to the discharge current. Assuming that the discharge current is 2 A, the voltage drop of the contribution of the equivalent series resistance in case 1 is 2 A × 0.07 Ω = 0.14 V, and the total of the voltage contribution of the capacity contribution and 2 V is 2.14 V. High current discharges are still possible. On the other hand, in Case 2, the voltage drop of the equivalent series resistance contribution is 2A × 0.55Ω = 1.1 V, and the sum of the voltage contribution of the capacitance contribution and 2 V is 3.1 V, and the rated voltage is 1.2. It exceeds 6 V, and high current discharge is no longer possible.

  As described above, since the magnitude of the value of B largely 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 considered in the unit 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 relations will be further described based on Table 2. Tables 2 to 4 show the upper limit of the wiring resistance value (the unit is from the range of the desired voltage drop at the beginning of discharge when the connection resistance per pole on one side is 5 types: 1mΩ, 5mΩ, 10mΩ, 30mΩ and 100mΩ). 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.

  The voltage drop at the initial stage of discharge is preferably 0.3 V or less in practice. It is more preferable if it is within 0.2 V. For example, assuming that the charge voltage is 2.6 V and the voltage drop at the initial stage of discharge is 0.3 V, the initial voltage of the discharge contributing to the discharge energy is 2.3 V obtained by subtracting the voltage drop. The discharge energy in this case can be maintained at about 78% as compared to the discharge energy at the initial voltage of 2.6 V, which is an acceptable value. The ratio for an initial voltage drop of 0.2 V improves to about 85% and for a voltage drop of 0.1 V to about 92%.

  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 the case of 150 mΩ is calculated as a representative example. Table 2 shows the upper limit of the wiring resistance of a single electrochemical cell, and Table 3 shows the upper limit of the wiring resistance 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 in the case where three single electrochemical cells are connected in series. Because they are electrochemical cells, they are often used in series to achieve the required rated voltage. Therefore, it is desirable to be able to be used in series connection.

  Here, the upper limit of the wiring resistance value was calculated assuming that the initial voltage drop was 0.3 V described above. In Table 2, when the voltage drop is 0.3 V, the column drawn with the horizontal line indicates that the upper limit of the wire resistance value is 0 mΩ or less. This means that the initial voltage drop exceeds 0.3V.

  Table 2 shows that when the connection resistance value is 1 mΩ and the discharge current is 1 A, the upper limit of the wiring resistance value is 148 mΩ. When the discharge current is further increased to 1.75 A, the upper limit of the wiring resistance value decreases to 19 mΩ. As described above, in order to be able to flow the discharge current value in a somewhat wide range, for example, the upper limit of the wiring resistance value is made to be about 10 mΩ in consideration of the maximum current value. The upper limit in the case of the connection resistance value of 5 mΩ is only 8 mΩ lower than that in the case of the connection resistance value of 1 mΩ. Also in this case, if the wiring resistance value is manufactured to 10 mΩ or less, it is possible to discharge to 1.75 A. If the connection resistance value is 10 mΩ, the voltage drop exceeds 0.3 V at a discharge current of 1.75 A, but if the wiring resistance value is in 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 is 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 margin of the wiring resistance value is improved as compared to the case where the connection resistance value is 100 mΩ, but when a 1.5 A current flows, the initial voltage drop exceeds 0.3 V The connection resistance value is also large. Therefore, the connection resistance value is preferably 10 mΩ or less.

  In the case of two series connection, as shown in Table 3, A of the equivalent series resistance is twice 150 mΩ, so the upper limit of the wiring resistance value is greatly suppressed, and it is necessary to reduce the maximum discharge current is there. For example, when the discharge current is 1 A, the voltage drop due to A of the equivalent series resistance is 1 A × 0.3 Ω = 0.3 V. Therefore, even if the connection resistance value is 1 mΩ, the upper 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 conditions of use with a voltage drop of 0.3 V or less. For a discharge current of 0.9 A, the upper limit of the wiring resistance is 6.5 mΩ for a connection resistance of 5 mΩ, but for a discharge current of 0.90 A for a connection resistance of 10 mΩ, the voltage drop is 0.3 V The difference is more than in the case where the connection resistance value is 5 mΩ or less. Therefore, in consideration of series connection applications, the connection resistance value is preferably 5 mΩ or less.

  In the case of 3 series, since the value of A of the equivalent series resistance is 150 mΩ × 3 = 450 mΩ, in order to make the voltage drop 0.3 V or less, the maximum current is also 0.3 V / 0.45 Ω, ie about 0 It will be about .65A. As shown in Table 4, when the connection resistance value is 5 mΩ, discharge of 0.6 A is also 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. As described above, when the number of stages connected in series increases, the influence of the connection resistance value on the wiring resistance value appears to be large. Therefore, considering only the specification with only a single electrochemical cell, the external container and the practicality are poor It is necessary to consider the above.

  The wiring resistance value depends on the resistivity and area of each of the pad film and the connection terminal, and the wiring and structure connecting them. The contribution of the in-base terminal of the present invention is large with respect to the increase in wire resistance value caused by the long wire. In particular, when the capacity of the electric double layer capacitor is increased to increase or prolong the discharge current or discharge time of the large current discharge, the size of the container increases, and the wiring tends to be elongated accordingly. By directly connecting the front and back of the base using the in-base terminal, it is possible to significantly reduce the wiring resistance.

  On the other hand, the reduction of the connection resistance value between the cell lead and the pad film largely contributes to welding. As a conductive adhesive for an electrochemical cell, a conductive filler is made of carbon or graphite, and a binder such as phenol resin has been suitably used. However, the connection resistance value differs greatly depending on the application conditions of the conductive adhesive, the surface condition of the metal to be connected, the heat curing conditions, the mounting temperature conditions to the substrate of the electrochemical cell, etc. It is difficult to design and manage the connection resistance in mΩ, which is required for high current discharge applications.

  FIGS. 2 (a) and 2 (b) are views showing the base inner side 1a and the base outer side 1b of the base 1, respectively. A pair of pad films 2 made of a conductive material is disposed on the base inner side surface 1a shown in FIG. 2 (a). Four in-base terminals 3 indicated by broken lines are provided on the lower surface of the pad film 2 and are vertically connected to connection terminals 4 (also indicated by broken lines) disposed 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 may be juxtaposed in the short side direction or arranged in the diagonal direction of the longitudinal direction. The pad film 2 does not necessarily have to be formed on the in-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, for example, by known film forming methods such as vapor deposition, ion plating, sputtering and the like. 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 to form an airtight inner base terminal 3 after finishing. In the case of film formation in vacuum, for example, a mask made of a metal or the like patterned so as to have two openings spatially separated from each other so as to respectively constitute the positive and negative pad films 2 is prepared. After being evacuated to a predetermined degree of vacuum with a vacuum evacuation system, the valve metal material is evaporated and the target consisting of the valve metal material is physically hit with ions to remove the material, and the base 1 Form a film on the inner side of the In these film formation methods, since the conditions for film formation are easy to control, it is possible to form a high-density film in which the resistivity of the formed film is low and in which liquid does not easily permeate.

  Also, an aluminum film can be formed by screen printing. For aluminum which is easily oxidized at high temperatures, a technology capable of forming a wiring pattern at a temperature of 150 ° C. or less has been developed. Since the printing method is used, a thick film of several tens of microns is easy as compared with thin film forming techniques such as vapor deposition.

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

  A pair of connection terminals 4 is provided on the base outer side 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 in the pattern of the mounting substrate by a reflow process or the like. In the connection terminal 4, for example, a plated film made of nickel and gold is applied to a tungsten pattern formed by a printing method. Tungsten and these plating materials are also patterned in the base side surface recessed part shown with the code number 1c, and function as a part of connecting terminal.

  Subsequently, the thickness of the pad film 2 will be described. The film thickness is preferably 5 μm or more and 100 μm or less. Preferably, the range of 10 μm or more and 30 μm is good. When the film thickness is small, the fine pores existing inside the film are connected, and the electrolyte is likely to penetrate the tungsten under the pad film to cause electrolytic corrosion of the tungsten, and as will be described later, When connected, the conditions of welding are extremely limited, which makes it difficult to achieve reliable joining.

  An experiment was conducted in which an aluminum thin film with a thickness of 80 μm was welded by ultrasonic welding after an aluminum film with a thickness of 5 μm was formed by ion plating on a soda lime glass plate with a thickness of approximately 1.3 mm. did. In one sample out of five cell leads, occurrence of micro cracks was observed in the glass plate. Therefore, 5 μm is a practical lower limit value for the film thickness. Practically, the film thickness is preferably 10 μm or more.

  On the other hand, the vapor deposition rate of aluminum by vapor deposition or ion plating is 3 μm to 10 μm per hour. In consideration of the deposition time, a thickness of 30 μm or less is preferable. In this case, the film formation time is at most about 4 to 5 hours. If the film is formed to a thickness of about 100 μm, the film forming time will be long, but welding conditions when connecting to the cell lead 8 by welding can be broadened, and a crack may be induced in the underlying ceramic. It can be very low.

  Next, a specific welding method of the cell lead 8 and the pad film 2 will be described with reference to FIG. FIG. 3A is a view showing the connection between a pair of cell leads 8 connected to the cell 7 and a pair of pad films 2. The tips of the pair of cell leads 8 are placed on the surface of the pad film 2 as shown in FIG. 3A, and then welded from the top surface of the cell leads 8 to bond the pad film 2 and the cell leads 8. By using welding, atomic diffusion of the materials constituting the respective members occurs at the bonding interface between the cell lead 8 and the pad film 2, which enables strong bonding. 8a of FIG. 3 (a) has shown typically the welded area | region. Since welding is performed, even when contamination such as a natural oxide film is present at the bonding interface, bonding with a sufficiently low connection resistance of mΩ or less can be achieved. Thus, the connection resistance can be reduced to 1/10 to 1/100 compared to the bonding method using a conductive adhesive or the like. In addition, it is possible to suppress the variation of the connection resistance value and to make the bonding less change with time.

  Further, by setting a plurality of bonding 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 formed inside the container. In the manufacturing process in which 7 is accommodated, generation of defects such as peeling of welding can be suppressed, and mechanical reliability such as vibration resistance characteristics and drop impact characteristics of the completed electrochemical cell can be improved.

  As welding of the cell lead 8 and the pad layer 2, specifically, a local welding method such as ultrasonic welding, beam welding, resistance welding or the like is suitable. That is, since these welding means have local portions to be welded, thermal effects remain only in the vicinity of the welds, and the influence on the cells 7 themselves 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 of mechanical or thermal impact on welding on the component can be reduced. With the above-described configuration, it is possible to prevent damage to the member due to the occurrence of a crack even with respect to the base 1 made of a material such as ceramics.

  FIG.3 (b) is a figure for demonstrating the concrete method of ultrasonic welding. In ultrasonic welding, as shown in FIG. 3 (b), first, the cell lead 8 is positioned on and in close contact with the pad film 2, but at this time, the cell 7 prevents movement of the ultrasonic welding tip 9. It is put out of the base 1 so as not to. Next, the ultrasonic welding tip 9 is brought into contact with the upper surface of the cell lead 8 by a moving mechanism with an appropriate pressure. The ultrasonic welding tip 9 is integrally formed at the horn tip or separately attached to the horn tip. The tip end 9 a of the ultrasonic welding tip 9 is a portion to be a contact surface with the cell lead 8, and an uneven pattern is provided on the surface so as to appropriately bite into the surface of the cell lead 8 ( It is preferable to use knurling.

  After the ultrasonic welding tip 9 is brought into contact with the cell lead 8 with an appropriate pressure, when the ultrasonic welding machine's oscillation mechanism applies an ultrasonic wave 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 an adhesion surface between clean surfaces of the metal material, and can be pressure-welded in a short time of several tens of milliseconds to several hundreds of milliseconds. The concavo-convex pattern on the surface of the cell lead 8 indicated by the weld area 8a of the cell lead and the pad film in FIG. 3A previously indicates that the concavo-convex pattern of the chip 9 for ultrasonic welding is transferred by this ultrasonic welding. It is shown schematically. Although the region 8a indicated by the concavo-convex pattern is a welding region, when viewed microscopically, the joined portion is only a portion that is recessed by a protrusion processed at the tip of the ultrasonic welding tip 9 In the other region, 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, care should be taken not to cause a large impact, and the moving mechanism should be provided with an impact absorbing mechanism such as a damper. This can reduce damage to the base material.

  Corresponds to various dimensions of the electrochemical cell by appropriately selecting the dimensions of the cell lead 8 (lead width and thickness), the dimensions of the pad film 2 (vertical dimension and thickness), and the dimensions of the ultrasonic welding tip 9 It is possible. The width dimension d of the ultrasonic welding area shown in FIG. 3 (a) is sufficient even if it is 0.5 mm, which is convenient for the fabrication of a small-sized electrochemical cell. Furthermore, in order to further increase the mechanical strength, by setting ultrasonic welding using ultrasonic welding tips 9 designed to cover substantially the entire area of the pad film 2, appropriate welding conditions are set. There is no influence on the inner base terminal and the base material, and sufficiently large mechanical strength can be obtained.

  In ultrasonic welding, it is possible to use not only vibration but also thermal energy and mechanical pressure. Further, although a thin plate-like example is shown as the cell lead 8 in FIG. 3A, it may be a wire, and the shape of the ultrasonic welding tip 9 may be appropriately deformed and used.

  Next, the case of beam welding will be described. Laser beam welding and electron beam welding are typical as beam welding. Not only are these welds capable of local processing, they are also non-contact methods, so there is no heat and wear degradation of the weld terminals. Therefore, the reproducibility is good. In addition, since the energy density is sufficient to melt the metal, short processing is possible. Electron beam welding has an extremely high energy density, high electron beam scanability, and places the cell 1 having the base 1 to be welded and the cell lead 8 in a vacuum to irradiate the electron beam in a vacuum. 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 YAG laser will be described below.

  A laser oscillator, a transmission fiber, a coaxial CCD monitor for positioning and surface observation 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 appropriate pressure. Irradiate the laser from the side. At the time of laser irradiation, in order to prevent oxidation of the bonding portion between the pad film 2 and the cell lead 8, an inert gas such as argon or nitrogen is sprayed, or an atmosphere of inert gas 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. A black circle 8a in the figure indicates a welding area irradiated with a laser and welded. Although aluminum has a low absorptivity of 1064 nm of a YAG laser (high reflectance material), the laser irradiation portion is heated, and the melting portion gradually spreads from the central portion of the heating. The heating reaches the surface of the lower pad film 2 to be joined from the lower surface of the cell lead 8 to melt the surface portion of the pad film 2 and the cell lead 8 and the pad film 2 are joined.

  Also in the case of laser welding, it is desirable to increase the welding area to further reduce the connection resistance value, and to achieve mechanical strength of the welding, and in FIG. I'm welding.

  Further, in FIG. 3A and FIG. 3C, one cell lead is welded to one pad film, but the number of cell leads may be plural. In the case where the length of the metal current collector supporting the active material is long, the metal current collector can be provided with a plurality of cell leads. In this case, it is preferable to connect the plurality of cell leads to one pad film because the resistance can be reduced.

  Although the above has described ultrasonic welding and beam welding as the welding method, the welding means is not limited to this and may be other means. For example, welding methods such as spot resistance welding and arc welding can also be used.

  As a base material of the outer container, ceramics is a commonly used material, but is not limited to ceramics. Soda lime glass, heat resistant glass and the like can also be used. Since 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. In addition, as a means for forming recesses and through holes in these glasses, it is possible to simultaneously form the recesses and the through holes using a chemical etching method, a physical method such as sand blast, or using a mold in a high temperature atmosphere. .

  In addition, after forming an aluminum film on the inner surface of the through hole, the through hole is filled with a glass paste whose thermal expansion coefficient is matched, and binder removal and firing are performed, whereby the airtight inner conductive base terminal 3 is provided. Can be formed. In such a case, there is no concern that the inner base terminal 3 dissolves. Therefore, it is not necessary to form the pad film 2 so as to cover the in-base terminal 3. Further, the film forming the inner surface of the in-base terminal 3 is not limited to aluminum, and may be a film containing another valve metal such as titanium.

Subsequently, the cell 7 will be described. The cell 7 is a separator made of an insulator and a pair of positive and negative electrode sheets supporting an active material on the surface thereof by coating or adhesion using an aluminum foil or copper foil having a thickness of 5 μm to 50 μm as a metal current collector. It is a power generation element integrated by methods such as winding, stacking and folding. In the case of the electric double layer capacitor, as a typical material of the active material, activated carbon or carbon can be mentioned. In lithium ion. Secondary batteries, as a positive electrode active material, for example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ) And the like, and as the negative electrode active material, for example, graphite, coke, and silicon oxide are used. The active material paste is prepared by mixing the above-mentioned active material with a conductive auxiliary agent, a binder, a dispersant and the like to adjust the viscosity to an appropriate viscosity, which is obtained by a method such as roller coating, screen coating, or doctor blade method. Apply to both sides or one side of the current collector. After coating, the electrode sheet is formed by drying and pressing.

  The separator regulates direct contact between the positive electrode and the negative electrode, and an insulating film having a high 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. The pore size and thickness of the separator are not particularly limited, but are determined based on the current value of the used device and the internal resistance of the electrochemical cell. It is also possible to use a porous ceramic body as a separator.

  The electrolyte comprises a non-aqueous solvent and a support salt. Also, the electrolyte may be liquid or solid. As a non-aqueous solvent for 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 or complex selected from high boiling point solvents such as propylene carbonate, ethylene carbonate, γ-butyrolactone and sulfolane. By using these solvents, the evaporation of the solvent can be prevented in a high temperature environment, and the internal pressure of the container can be suppressed.

The support salt comprises an electrolyte cation and an electrolyte anion. As the electrolyte cation, at least one salt of quaternary ammonium salt, quaternary phosphonium salt, imidazolium salt, pyrrolidinium salt, phosphonium salt, or thiocyanate salt, lithium salt and the like is used. BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , or N (CF ₃ SO ₂ ) ₂ ⁻ is used as the electrolyte anion.

  In addition, the electrolyte may be 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 polymer, PVDF or the like in combination with a non-aqueous solvent and a support salt to form a gel or It can also be used in solid form.

It is also possible to use an inorganic solid electrolyte _{LiS / SiS 2 / Li 4 SiO} 4. Furthermore, as the electrolyte, ionic liquid such as pyridine type, alicyclic amine type, aliphatic amine type or imidazolium type, or a normal temperature molten salt such as amidine type may be used.

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

  In resistance seam welding, which is used as a method of welding the two, after bringing the lid 6 into contact with the bonding metal member 5, the trapezoidal shaped roller electrodes opposed to each other at approximately two points on the long side of the lid 6 are disposed. Then, a low voltage and a large current flow for a short time, and temporary welding (spot welding) of the lid 6 is performed. In this manner, 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 can be 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 manner, welding is performed over the circumference of the lid 6. Also in the above-described temporary fixation, also in the present resistance seam welding, diffusion of gold and nickel occurs at the interface between the lid 6 and the bonding metal member 5 to form an airtight and strong diffusion bonding layer. Thus, the lid 6 is airtightly sealed to the base 1.

  The welding of the base 1 and the lid 6 is also possible using scanning irradiation of a laser. After temporary welding is performed as described above, a laser is scanned and irradiated around the lid. Thus, a diffusion bonding layer is formed at the interface between the lid 6 and the bonding metal member 5. In this case, it is also possible to lower the melting temperature to the temperature of the brazing material by sticking a sheet of the brazing material made of silver and copper on the surface of the lid 6 on the bonding side.

  When the electrolyte is a liquid solvent or support salt at room temperature and the electrolyte is filled before the lid 6 is sealed, the liquid is present at the interface between the lid 6 and the bonding metal member 5. You can get it. Even in such a case, joining using seam welding is possible. The seam welding may use a roller electrode or may use laser scanning irradiation. Even if liquid is present at the interface, airtight welding is possible because the liquid present at the interface is considered to be due to evaporation and scattering since the temperature in the vicinity of welding rapidly rises.

  Subsequently, modified examples of the invention will be described. First, a modification of the structure of the in-base terminal will be described.

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

  The pad film 2 is formed of an aluminum film with a thickness of 5 μm to 100 μm, as described above. A pair of cell leads 8 connected to the cells 7 are connected to the pad film 2 by welding. Further, after the electrolyte is filled, the base 1 and the lid 6 are airtightly sealed to constitute an outer container.

  As shown in FIG. 4 (b), at the interface of the lower ceramic plate 1e, the wiring pattern 10 made of a metal film such as tungsten connected to the in-base terminal 3 has a solid wide area as shown by oblique lines. Provided in And it is pulled out horizontally to the end by the side of the long side of base bottom composition board 1e of a ceramic board, and is extended to the side. The extension is connected to the connection electrode 4. Since such a solid wiring pattern is used, the resistance value of the wiring pattern can be suppressed low.

  On the other hand, in FIG. 4C, a straight wiring pattern 10a of width d extends outward from each point corresponding to the in-base terminal 3. 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 of FIG. 4B. Therefore, the wiring pattern needs to be determined in consideration of the number of in-base terminals, the width d, the lengths (L1 and L2), and the sheet resistance value of the wiring pattern.

  An example of the above wiring resistance value will be described below. For example, it is assumed that 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 of a tungsten film having a thickness of about 10 μm. The resistance value of the wiring pattern in the portion of the length L1 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 to be 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 the positive electrode and the negative electrode, the approximate resistance value of this wiring pattern is estimated to be 60 mΩ.

  Assuming that 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 in the same calculation. It can be reduced by half in comparison. 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 expanded 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 outer container is a value obtained by adding the wiring resistance value of the side area and the wiring resistance value of the connection terminal in addition to the resistance value of the above wiring pattern.

  As shown in the present modification, the filled 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 can be combined with the wiring patterns 10 and 10a having appropriate resistance values. It can be used for the high current discharge application which is the object of the invention.

  Then, the example which provided the penetration area | region in the bottom face and side wall of a base is demonstrated based on FIG. FIG. 5A is a cross-sectional view of the electrochemical cell of this modification. FIG. 5B is a schematic view for explaining the base of the present modification, in which the lid connecting metal layer 5 is omitted. The protective film 11 shown in FIG. 5A is also omitted. The protective film 11 will be described later.

  A solid wiring pattern 10 functioning as a current collector is provided on the base inner side surface 1a of the base 1, and a pad film 2 is provided thereon. The wiring pattern 10 is made of a high melting point 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 on the side surface, and further connects to the connection terminal 4 from the side surface of the base 1 ing. In FIG. 5A, the pad films 2 are provided on the positive and negative electrodes, but may be formed on the wiring pattern 10 corresponding to at least the positive electrode.

  The cell lead 8 connected to the cell 7 is a connection terminal via a pattern of the total length of the wiring patterns 10 of lengths L3 and L4 and the side portion (indicated by reference numeral 10b) of the wiring pattern of length L5. Connected to four. Therefore, in the wiring resistance value, the total value of the lengths 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 general example of the wiring resistance value which the wiring patterns 10 and 10b have is shown.

  As numerical examples, values of L3, L4, and L5 are respectively 3.4 mm, 0.8 mm, and 0.5 mm. This dimension is a numerical value supposing the ceramic package which consists of a rectangular solid with a long side of 10 mm, a short side of 5 mm, and a height of 3 mm shown in Example 1 to be described 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 surface. Also, the value of L3 is a value that allows sufficient separation of the two pad films of the positive electrode and the negative electrode in the vapor deposition method even when arranged side by side, and the addition value with L4 is half of the long side A number smaller than the length but as close as possible is selected. As the two sheet resistance values, the pattern portion (L3 and L5) of the tungsten film plated with nickel and gold is set to 5 mΩ, and to 10 mΩ in L4 to be a film of only tungsten. Further, the width d2 of the wiring pattern is 3.0 mm. Here, the numerical value of d2 adopts the numerical value close to 3.4 mm (the short side of the inner bottom surface of the base) which is the value obtained by subtracting the thickness 1.6 mm of the two side walls from the length 5 mm of the short side. The wiring resistance value of the wiring pattern is suppressed as shown in FIG.

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

  If the wiring resistance value is about 13 mΩ in combination of the positive electrode and the negative electrode, and the connection resistance value of one side of the electrode is 1 mΩ or less, as described in Table 2, a single electrochemical cell produces 1.75 A of discharge current Also, the initial voltage drop is 0.3 V 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 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 if three series are used. That is, this modification can be used for a large current discharge application.

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

  In FIG. 5D, a film different from 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 contacting the electrolyte. Here, the protective film 11 has adhesion to the surface of the wiring pattern 10 and the base material, electrolytic resistance characteristics, electrolyte impermeability, temperature characteristics at the time of mounting on a substrate, easiness of film formation, coating, etc., curing temperature It is determined in consideration of The protective film 11 is not limited to one layer, and may be a multilayer film coated with a plurality of films. As the protective film 11, an inorganic coating material, a butyl-based rubber, a polyimide, a heat resistant resin based on polyamideimide, an epoxy-based ultraviolet curable resin, or the like can be used. The curing temperature is about 100.degree. C. for epoxy-based UV curable resins and the like, about 120.degree. C. to 150.degree. C. for inorganic coating materials, and about 230.degree. C. to 270.degree. 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 the present modification, the wiring resistance value can be suppressed to a sufficiently low value. Moreover, since the wiring pattern 10 which functions as a collector by the protective film 11 is not exposed to the electrolyte, it can be used stably for the large current discharge application intended by the present invention.

  Subsequently, a further modified example will be described based on FIG. The electrochemical cell shown in FIG. 6A is a cross-sectional view in which a base 1 made of a flat ceramic plate and a metal lid 6a having a concave shape are used as an outer container. The cell 7, the pair of cell leads 8, the pair of pad films 2, the in-base terminal 3 and the electrolyte are housed inside the container as in the above-mentioned invention, and the cell leads 8 and the pad films 2 are welded Connected by

  As shown in FIG. 6A, the lid 6a is welded with its opening portion in contact with a bonding metal member 5 provided around the base 1 so as to cover the cell 7 and the like. Laser welding is preferred for this welding. Moreover, when performing seam welding, it is scanningly irradiated from the arrow direction of Fig.6 (a). In resistance seam welding using a roller electrode, the roller electrode easily contacts the step of the lid 6a, and it becomes difficult to cause the roller electrode to abut on the joint properly.

  In the lid 6a, small holes are provided in the bottom of the lid 6a. This is intended to fill the electrolyte from the small holes after welding the base 1 and the lid 6a, and then to seal the container airtightly using the sealing plug 6b. As a result, it is possible to prevent the efficiency of the sealing operation from being lowered due to the presence of the electrolyte between the base bonding metal layer 5 and the bonding surface of the lid 6a. The material and thickness range of the pad film 2 formed on the inner side of the base 1, the structure and number of the in-base terminals 3, and the means for bonding the cell lead 8 and the pad film 2 are the same as described above. I omit it.

  The electrochemical cell shown in FIG. 6 (b) has the same configuration as that of FIG. 6 (a), but the joining metal member 5 disposed around the flat base 1 is inserted into the step provided on the base The difference in height between the bonding metal member 5 and the inner surface of the base is sufficiently reduced. As a result, even if the cell 7 is disposed in the lid 6a after the electrolyte is charged in a state where the lid 6a is upside down, the electrolytic mass overflowing from the lid 6a can be reduced. Therefore, with the configuration shown in FIG. 6 (b), welding between the base 1 and the lid 6a can be easily performed even in a state where the electrolyte is filled. Therefore, the small hole of the lid 6a as shown in FIG. 6A is not necessary, and the sealing process by the sealing plug 6b can be omitted.

  Subsequently, another modified example will be described with reference to FIG. FIG. 7A shows the 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, and thereby a concave container is formed. An in-base terminal 3 penetrating directly to the outer surface of the base is provided on the inner base surface 1a of the base, and a pair of pad films 2 is disposed thereon. The metal side wall 12 made of metal is selected so that the coefficient of thermal expansion matches the flat plate of the base, and is joined to the flat plate with a brazing material. On the other hand, the opening on the opposite side forms a bonding surface of the lid 6. In the present modification, the bonding metal member 5 for sealing the lid 6 is unnecessary, and the metal side wall 12 itself also plays the role of the bonding metal member 5. Therefore, a plated film of nickel and gold is applied to at least the surface to be bonded to the lid 6, and the lid 6 is abutted to the plated surface and can be bonded using resistance seam welding or laser seam welding. Is configured as.

  FIG. 7 (b) shows a cross-sectional view of an electrochemical cell using a base. A pair of cell leads 8 connected to the cell 7 is connected to the pad film 2 by welding means and connected to the connection terminal 4 by the in-base terminal 3. An electrolyte (not shown) is filled in the container and hermetically sealed by the 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. Moreover, the shape can select a corner, a track shape, an ellipse, a circle, etc. In particular, when a standard hollow pipe is cut at an arbitrary length and used, the height of the electrochemical cell can be freely determined, and the manufacturing cost can be reduced.

  In the electrochemical cell shown in FIG. 7 (c), the metal side wall 12 made of metal is used as in FIG. 7 (b), but the pad film 2 is an example limited to only the positive electrode side. The lead 8 b on the positive electrode side is connected to the pad film 2, while the cell lead 8 c on the negative electrode side is connected to the inside of the metal side wall 12 made of metal by welding. Furthermore, the connection terminal 4 corresponding to the negative electrode is configured to be electrically connected to the metal side wall. As a result, since the metal side wall 12 is made of metal and the current flow path is large, the wiring resistance value on the negative electrode side can be suppressed low. Therefore, the electrochemical cell of the present invention can also perform high current discharge.

  Subsequently, still another modification will be described with reference to FIG. FIG. 8 shows a cross section of the electrochemical cell. A pad film 2 made of an aluminum film is provided on the inner bottom surface 1a of the concave container 1 made of ceramic in the same manner as described above. It is connected to 4. In the present 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 the winding method or the 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 when 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, it is well known to ultrasonic welding, laser spot welding, resistance spot welding, arc welding etc. It is possible to connect by the welding method of Therefore, it is possible to keep the connection resistance value sufficiently low also on the negative electrode side.

  The connection terminal on the negative electrode side is extended from the bottom surface 1 b of the container along the side surface to the bonding metal member 5 and is electrically connected to the lid 6. The extended portion is referred to as the extended portion 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 reduced to a low level, so that the wiring resistance value on the negative electrode side can be configured without a large increase.

  The container 1 is filled with an electrolyte (not shown), and the lid 6 is welded to the bonding metal member 5 to form an airtight container. In the lithium ion secondary battery, a copper foil is commonly used as a current collector material of the negative electrode, and a thin plate of nickel is commonly used as a cell lead, but it is possible to apply this modification. Therefore, it is possible to manufacture a highly reliable small and thin lithium ion secondary battery having high airtightness characteristics.

In addition, the extended part was provided in the outer side of the container in this modification. The connection between the lid 6 and the connection terminal 4 is not limited to this, and it is easy to form a hole in the lower part of the bonding metal member 5 and form a conductive material on the inner surface to connect to the connection terminal 4.
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. 1 (a) and 1 (b) and a lid 6 were prepared as outer containers. The base 1 has a long side of 10 mm, a short side of 5 mm, and a height of 2.85 mm. The thickness of the base of the base 1 is 0.5 mm. As a material, a standard material was used when producing a package of electronic parts with ceramics. The material has a tensile strength of 400 MPa and a Young's modulus of 310 GPa. The region in which the pad film 2 is to be formed is filled with tungsten and plated on its surface with nickel and gold so that the inner base terminal 3 with an inner diameter of 0.2 mm directly penetrates the inner surface and outer surface of the base, Four each were provided. A pair of connection terminals 4 is disposed on the base outer surface 1 b and connected to the in-base terminal 3. The connection terminals are plated with gold on nickel (S10).

  Next, on the base inner side surface 1a, a pair of pad films 2 made of a vapor deposited film of aluminum was formed. The dimensions of the pad film 2 are 2.4 mm for the long side and 2 mm for the short side, and the thickness is 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 electrolytically nickel plated (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 consisting of activated carbon, a conductive auxiliary material, a binder and a thickener according to a coating method to obtain a sheet electrode (S30). After cutting into 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 positive and negative sheet-like electrode to which the cell lead 8 was welded, and then a winding core was inserted and wound into a track shape. Thereafter, the core is taken out and the gap is squeezed lightly to form a wound electrode (S32).

  Then, ultrasonic welding is performed. The cell lead 8 was positioned in close contact with the surface of the pad film 2 of the base 1 prepared above. The ultrasonic welding performed cell leads one by one (S33). The oscillation frequency of the ultrasonic bath 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 tip 9 for ultrasonic welding, a 0.2 mm pitch staggered grid-like uneven pattern (narl) was provided in a region of 2 × 1.5 mm. The difference between the height of the mountain and the bottom of the valley is 0.2 mm. The welding mode is a mode for controlling the energy supplied to the cell lead 8 during welding, the setting value of the welding energy is 15 J, and the maximum value of the welding time is 60 msec. The ultrasonic welding tip 9 descends to the surface of the cell lead 8 made of aluminum by an air mechanism, then bites into the surface of the cell lead 8 and vibrates between the interface of the cell lead 8 and the pad film 2 to perform welding. .

  After welding, the cell lead 8 was folded and the cell 7 was stored in the base 1. At this time, care was taken that the cell lead 8 was not mixed with the bonding metal member 5 (S34). This is to avoid cell shorts.

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

The electrical characteristics of the manufactured electric double layer capacitor of Example 1 were examined (S37). The items were measured equivalent series resistance and capacitance. The equivalent series resistance used the alternating current resistance method in AC1 KHz. In addition, as the capacity, a discharge method (a measurement current of 10 mA was set between 2 V and 1 V) was used.
(Comparative example 1)
A cell 7 was manufactured using a sheet electrode having the same dimensions as in Example 1. Here, the cell lead had the same material, width and thickness as in Example 1, but had a length of 40 mm. Next, it filled up with the same electrolyte, and stored in the exterior container which consists of an aluminum laminate film. Thus, an electric double layer capacitor using the aluminum laminate package of the comparative example was produced. Since the comparative example 1 does not have a pad film, the connection resistance has a value which is a practical value.

  The electrical characteristics of the manufactured electric double layer capacitor of Comparative Example 1 were examined in the same manner as in Example 1.

  The equivalent series resistance of Example 1 was 310 mΩ. In addition, the capacity was 170 mF. The measured value of the equivalent series resistance of Comparative Example 1 was 320 mΩ. Moreover, the capacity | capacitance was 180 mF substantially the same as Example 1. That is, it is understood that the wiring resistance value can be suppressed to a practical level even by welding the pad film and the cell lead. Among the values of the equivalent series resistances of Example 1 and Comparative Example 1, Table 5 shows a comparison of the resistance of the outer container including the resistance value of the cell lead 8.

  In Table 5, the value of 2.4 mΩ in the column of the connection resistance value and the like 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 in-R3 base 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 and the like is a value obtained by separately preparing and measuring a measurement sample. As described above, since six charge through holes 3 are arranged for one pad film 2, resistance value R3 of charge through hole 3 is a resistance value to which these six through holes contribute. ing. In the aluminum laminate package of the comparative example, the value of the connection resistance and the like is 0 mΩ because the cell lead is exposed outside the package and connected to the measurement terminal of the measuring instrument. The numerical values are all the sum of the positive electrode and the negative electrode.

  The numerical values of the connection resistance values and so on in Table 5 are 1.2 mΩ for the electrode on one side only and 2.4 mΩ for both electrodes, so it is understood that in the present example, the respective numerical values from R1 to R4 are sufficiently low first . The connection resistance value of the cell lead and the pad film is calculated to be 1 mΩ or less based on a number of separate experiments performed assuming that the resistivity of the aluminum vapor deposition film forming the pad film is 6.6 μΩcm. Since the deposition film of aluminum is usually about 2.2 to 2.7 times the value of the bulk (2.75 μΩcm), 6.6 μΩcm is a value corresponding to 2.4 times, which seems appropriate Be

Further, by the structure in which six in-base terminals 3 are directly connected to the connection terminals 4, the wiring resistance value consisting of the sum of R1, R2 and R3 is also suppressed sufficiently low. Therefore, in the column of the total value in Table 5, the total of Example 1 is 5.2 mΩ, which is equivalent to 13.6 mΩ which is the total value of the aluminum laminate package.
(Comparative example 2)
In order to compare the above connection resistance value with the connection resistance value in the case of the connection means using the conductive adhesive, the same base 1 and aluminum thin plate as in Example 1 are connected using the conductive adhesive. The connection resistance value was obtained. The main conductive fillers of the conductive adhesive are graphite and carbon. The results are shown in Table 6.

The conductive adhesives D1 and D2 are commonly used in the case of bonding a sheet-like electrode obtained by kneading activated carbon, carbon and polytetrafluoroethylene powder to aluminum or stainless steel. Further, D3 is a conductive paint, which can be applied to aluminum and 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 was a value exceeding 10Ω between D1 and D2. Since such a value causes a significant voltage drop due to charge and discharge, it is unsuitable for the high current discharge intended by the present invention. Since the connection resistance value of Example 1 was 1 mΩ or less as described above, the numerical value achieved was also lower by three digits than that of Comparative Example 2. Although the connection resistance value converted into (1 cm ² ) per unit area is described in Table 6, even if the connection area is expanded to 1 cm ² , it is 300 mΩ or more, which is an excessively large value as the connection resistance value. . Connections using conductive adhesives are unsuitable for electrochemical cells using the small outer container intended by the present invention. That is, the connection resistance value of the electrochemical cell according to the present invention in which the cell lead and the pad film are connected by welding is extremely low compared to the electrochemical cell in which the cell lead and the pad film are connected using the conductive adhesive which is the conventional method. It becomes clear that

  Then, the influence of the heat in the reflow process of the sample created in Example 1 was examined. After subjecting the sample to reflow processing with a reflow apparatus applied for several seconds at a maximum temperature of 270 ° C., the exterior container appearance was closely observed with an optical microscope. No cracks were observed on the base 1. Further, the electrolyte did not leak in the vicinity of the through electrode opening of the lower surface of the base as well as the resistance seam weld between the base 1 and the lid 6.

  Furthermore, the same members were separately welded under the condition that the cell lead 8 and the pad film 2 were ultrasonically welded, and the cross section of the bonding interface was observed with an optical microscope. A sample obtained by ultrasonic welding of the cell lead 8 and the pad film 2 was embedded in a resin and solidified, and then polished gradually 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 bite was joined to the aluminum film forming the pad film. Further, in the vicinity where the chip was in contact with the recess, a gap of several μm was observed with the pad of the aluminum film. That is, the cell lead 8 and the pad film 2 were bonded at a bonding point corresponding to the unevenness of the ultrasonic welding tip. Then, in the cross section of the ceramic corresponding to the lower surface of the pad film 2, generation of cracks was not recognized including the vicinity where the in-base terminal 3 was formed.

As mentioned above, since the structure which suppresses wiring resistance value low by arrangement | positioning of the in-base terminal directly connected to the outer surface from the inner surface of a base was adopted and it was set as the structure which connects cell lead 8 and the pad film 2 by ultrasonic welding, The resistance value is also low enough to realize an electrochemical device for high current discharge applications. And, by setting appropriate welding conditions, welding can be performed without damaging the base, so that an electrochemical cell with high reliability can be manufactured.
(Example 2)
The step of bonding the cell lead 8 and the pad film 2 was performed by spot welding using a YAG laser. In addition, the oxidation of the joint at the time of welding was prevented by blowing nitrogen.

  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 concave container has the same structure as the structure shown in FIG. 4C described in the second modification, and six in-base terminals penetrating halfway through the base are provided. . The thickness of the bottom of the base is 0.3 mm thinner than that of Example 1, and aluminum is formed on the inner side of the base to a thickness of about 25 μm by vapor deposition. The dimensions of the pad film are rectangular 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 end portion of the lead 8 were mechanically pressed so as to maintain close contact, and then spot welding was performed at two places using a YAG laser. The welding conditions here are 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 on the bottom of the base and then measuring the space between the cell lead and the copper lead using the above-described resistance meter. The resistance value (sum of the connection resistance value and the wiring resistance value of the base) obtained by subtracting the wiring resistance value of the cell lead and the copper lead from the total value was in the range of about 38 to 40 mΩ. 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 the area of 2.0 × 0.5 mm). The above-described resistance value (sum of connection resistance value and wiring resistance value of the base) was also in substantially the same range. Thus, it is assumed that the connection resistance value in the case of laser welding is approximately the same as that in the case of ultrasonic welding.

Apart from this sample, cross-sectional observation of the laser-welded portion was performed under the same welding conditions. According to the cross-sectional observation with an optical microscope, the connection point 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. In addition, no damage such as a crack was found in the ceramic around this connection region. Thereby, a method using a laser as a welding means is also possible.
(Example 3)
The material of the base in each of Examples 1 and 2 was a ceramic. In this embodiment, the case where the base material is glass will be described. An aluminum film was formed by ion plating on the surface (one side) of soda lime glass (about 1.3 mm in thickness). The thickness was 5 μm. On this aluminum surface, a thin plate of aluminum having a thickness of 80 μm and a width of 2 mm (the same as that used for the cell lead 8 in Example 1) was welded using ultrasonic welding. The ultrasonic welding was performed at an oscillation frequency of 62.5 KHz. The area of the tip of the ultrasonic welding tip is 2 mm on the long side and 0.5 mm on the short side, and the surface of the tip is processed with a zigzag grid of irregularities.

  Under the present welding conditions, 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 between two thin aluminum plates by ultrasonic welding and the connection resistance value, 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, but may be a brittle material such as soda lime glass. Since the technology for forming the base inner terminal on soda lime glass or heat resistant glass is known as described above, it can be used as a base material of an electrochemical cell for high 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 package for electronic parts. A sample was prepared in which a large number of in-base terminals with an inner diameter of 0.3 mm were provided at a pitch of 0.5 mm in the XY direction on a plate made of ceramics with a thickness of 0.3 mm. On the open face of the in-base terminal, a solid tungsten pattern was provided on both the front and back surfaces so as to connect the in-base terminals to each other. The thickness of tungsten is 10 μm, and the surface is plated with nickel and gold. As a cell lead, an aluminum thin 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 in Example 3.

  The observation of the welded cross section of the sample welded under the above-described welding conditions was performed in the same manner as in Example 1. The vicinity of the opening of the large number of arranged through holes was carefully observed with an optical microscope, but no crack was observed in the ceramic. That is, on the side of the current collector for the negative electrode, the same welding means for the positive electrode can be applied 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 convenient in manufacturing.

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 a coat of a valve metal such as aluminum, but it is not always necessary for the negative electrode. Not required for current collectors. The aluminum pad film described above may be provided only at least on the current collector for the positive electrode. At this time, the current collector for the negative electrode is a tungsten film used when forming the in-base terminal, and a film in which the surface is plated with nickel and gold is formed.
If the above-mentioned welding for connecting the cell lead 8 and the pad film 2 can also be applied to the connection of the other cell lead 8 and the tungsten film, it is convenient in manufacture.
(Example 5)
The cell leads 8 shown in Examples 1 to 4 described above were all aluminum. In the fifth embodiment, the material of the cell lead 8 is nickel. A nickel lead is commonly used as a lead for a lithium ion secondary battery negative electrode. 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 outer container.

  On a 0.5 mm thick ceramic plate made of the same material as that of Example 1, aluminum having a thickness of 5 μm was vapor-deposited to form a pad film. Ultrasonic welding was performed by arranging a nickel lead having a width of 6 mm and a thickness of 100 μm. On the surface of the tip for ultrasonic welding, an uneven pattern of a 0.7 mm pitch staggered grid was provided in an area of 4 mm × 3 mm. The difference between the mountain and the valley is 0.30 mm. The 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. The pressure of air was 0.1 MPa, welding energy was 22.1 joules, and welding amplitude was about 13 μm, and welding with sufficient welding strength was possible.

  After the bonded members were embedded in a resin as described above, polishing was performed and cross-sectional observation of the bonded portion was performed. Detailed observation was made, but there was no crack in the ceramic part. Therefore, even when a nickel lead is used for the cell lead, it is possible to construct an electrochemical cell having the structure of the present invention.

The pad film made of aluminum to which a nickel lead is connected for the negative electrode of a lithium ion secondary battery is preferably coated with an insulating paint so as not to be exposed to the electrolytic solution.
(Example 6)
In the present 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 placed on the aluminum pad film formed to a thickness of 5 μm. The same ultrasonic welding tip as in Example 5 was used. The ultrasonic welding tip was pressed against the surface of the copper foil for welding. The conditions for welding were the same as in Example 5. That is, the welding mode is a method of specifying a welding time, a constant welding time of 0.15 seconds, an air pressure of 0.1 MPa, a welding energy of 22.1 joules, and a welding amplitude of about 13 μm. Under these conditions, welding with sufficient welding strength was possible, and the copper foil did not peel off.

  After the bonded members were embedded in a resin as described above, they were polished and cross-sectional observation of the bonded portion was performed. Detailed observation was made, but there was no crack in the ceramic part. Therefore, even when a copper lead is used for the cell lead, it is possible to construct an electrochemical cell having the structure of the present invention.

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

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

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

Reference Signs List 1 base 1a base inner side surface 1b base outer side surface 1c base side surface 1d base bottom surface configuration plate 1e base bottom surface configuration plate 1f base side wall inner side surface 2 pad film 3 base internal terminal 4 connection terminal 4b extension portion 5 bonding metal member 6 lid 6a cavity Mold lid 6b Sealing plug 7 Cell 8 Cell lead 8a Welding area 8b of cell lead and pad film Positive electrode cell lead 8c Negative electrode cell lead 9 Ultrasonic welding chip 9a Tip tip 10, 10a, 10b Wiring pattern 11 Protective film 12 Metal side wall

Claims (5)

An electrochemical cell comprising an outer case comprising a base and a lid, a cell housed in the outer case, and an electrolyte,
At least one pad film made of aluminum and connected by welding to a cell lead which is an extension of the cell is formed on an inner side surface of the base.
A connection terminal is provided on the outer surface of the base,
The connection terminal and the pad film are electrically connected via an in-base terminal made of a high melting point metal,
Furthermore, the pad film is coated with an insulating paint. An electrochemical cell comprising an outer case comprising a base and a lid, a cell housed in the outer case, and an electrolyte,
At least one pad film made of aluminum and connected by welding to a cell lead which is an extension of the cell is formed on an inner side surface of the base.
A connection terminal is provided on the outer surface of the base,
The connection terminal and the pad film are electrically connected via an in-base terminal made of a high melting point metal,
Furthermore, an inner surface side of the base of the in-base terminal is covered with a protective film of a material different from that of the pad film. The electrochemical cell according to claim 1 or 2, wherein the cell leads of the positive electrode and the negative electrode among the cell leads are electrically connected to the pad film. The cell lead of the positive electrode of the cell leads is electrically connected to the pad film, and the cell lead of the negative electrode is electrically connected to the lid. The electrochemical cell described in. The electrochemical cell according to any one of claims 1 to 4, wherein the outer container is a container in which the base and the lid are sealed via a bonding metal member.

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