JP2010267984A - Electrochemical cell and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem; while the covering of the surface of a positive electrode collector with a valve metal has been examined in order to prevent dissolution of the positive electrode collector even at a high potential in a conventional electrochemical cell using a heat-resistant container, the covering method which is optimum in terms of performances and costs is not found. <P>SOLUTION: By covering the positive electrode collector with the valve metal by a shot coating method so as to prevent the dissolution of the positive electrode collector even at the high potential, the electrochemical cell superior in terms of performances and costs is manufactured. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a surface-mountable electrochemical cell, that is, a non-aqueous electrolyte battery and an electric double layer capacitor utilizing the electric double layer principle.

  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.

  A small electrochemical cell is required to have a large capacity and current due to the non-volatile semiconductor memory and the low power consumption of the timepiece functional element. Rather, the needs of electrochemical cells include thinness and reflow soldering (coating solder cream on the part to be soldered on the printed circuit board in advance and placing the part on that part, or mounting the part A printed circuit board in which solder spheres (solder bumps) are supplied to the soldered part after placement, and the parts are mounted in a furnace in a high-temperature atmosphere set so that the soldered part has a melting point higher than the solder, for example, 200 to 260 ° C. Therefore, there is a strong demand for a method of melting the solder and soldering.

  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.

  From the above, an electrochemical cell using a heat-resistant container as an exterior body for housing an electrode and an electrolyte and having a terminal has been studied (for example, see Patent Document 1).

JP 2001-216852 A (2nd to 3rd terms, FIG. 1)

  In an electrochemical cell using a heat-resistant container, a positive electrode active material is disposed on the bottom side of the container, and the positive electrode current collector and the positive electrode active material are in contact via a valve metal layer and a conductive adhesive. Is configured. The container is sealed with a lid. In addition, a connection terminal A and a connection terminal B are provided for connection to an external circuit.

  When the electrochemical cell is used at a relatively high voltage, for example, around 3 V, the positive electrode current collector in contact with the positive electrode active material is dissolved, and thus a valve metal layer having excellent corrosion resistance is provided. The valve metal layer prevents dissolution of the positive electrode current collector. As a method for forming the valve metal layer, there are CVD, vapor deposition, sputtering, thermal spraying, plating, and the like.

  However, CVD, vapor deposition, and sputtering have problems such as requiring a large-scale apparatus and a small amount that can be processed at one time.

  An object of the present invention is to provide an electrochemical cell that solves the above problems and does not cause corrosion inside.

  In the present invention, a valve metal layer is formed on the positive electrode current collector by a shot coating method so that the positive electrode current collector does not dissolve even at a high potential, and the positive electrode current collector is covered to prevent dissolution of the positive electrode current collector. It is possible to provide an electrochemical cell superior in performance and cost. Aluminum, tantalum, niobium, titanium, hafnium, and zirconium can be used for the valve metal layer formed by the shot coating method.

  The electrochemical cell of the present invention comprises a positive electrode current collector coated with a valve metal layer formed by a shot coating method, a positive electrode comprising a positive electrode active material and the positive electrode current collector, a negative electrode containing a negative electrode active material, An ion-conductive electrolyte; a container made of a heat-resistant material that houses the positive electrode, the negative electrode, and the electrolyte; and a lid for sealing the container.

  In addition, the method for producing an electrochemical cell according to the present invention includes a first step of forming a valve metal layer by a shot coating method on a positive electrode current collector provided at the bottom of a container, and the above-described via the valve metal layer. A second step of bonding the positive electrode current collector and the positive electrode, a third step of disposing a separator on the electrode, a fourth step of injecting an electrolyte into the container, and a fifth step of bonding the negative electrode to the lid, It consists of a sixth step of welding and sealing the container and the lid.

  The shot coating method can form a dense and uniform film without requiring a large-scale apparatus, and can effectively prevent dissolution of the positive electrode current collector.

  Aluminum, tantalum, niobium, titanium, hafnium, and zirconium can be used for the valve metal layer to be coated by the shot coating method. Use of these metals can withstand the high potential of the positive electrode, and has the effect of improving the performance and storage characteristics of the electrochemical cell.

  Among the valve metals, aluminum is particularly excellent. It is easy to form a film having a uniform thickness. In the shot coating method, a uniform film could be stably formed by hitting aluminum particles having an average particle diameter of 4 to 20 μm at a speed of 100 to 400 m / s.

  When the valve metal of the valve metal layer formed by the shot coating method is aluminum, dissolution of the positive electrode current collector can be effectively prevented by setting the film thickness of aluminum to 5 to 30 μm. An aluminum film thickness of less than 5 μm is not preferable because the positive electrode current collector is dissolved because the film thickness is small. Further, when the aluminum film thickness is greater than 30 μm, peeling occurs.

  By using air as the carrier gas for carrying shot coating aluminum particles, an aluminum film can be formed safely and inexpensively.

  A portion of the positive electrode current collector is embedded in the concave container, and at least a portion of the positive electrode current collector that is not embedded is covered with a valve metal by a shot coating method, thereby affecting the influence of film defects such as pinholes. Less receiving and improved reliability.

It is sectional drawing of the electrochemical cell of this invention. It is sectional drawing of the electrochemical cell of this invention. It is a top view of the container of the present invention. It is sectional drawing at the time of putting a metal mask on the container of this invention. It is a perspective view at the time of forming a valve metal layer in the container of the present invention.

  An electrochemical cell according to the present invention will be described with reference to FIG. A positive electrode active material 106 is arranged on the bottom surface side of the concave container 101, and a positive electrode is formed by the positive electrode current collector 103 and the positive electrode active material 106. A valve metal layer 112 is formed on the surface of the positive electrode current collector 103 by a shot coating method, and the positive electrode current collector 103 and the positive electrode active material 106 are electrically connected via the valve metal layer 112.

  Valve metal particles are sprayed onto the surface of the positive electrode current collector by the blast device, and a valve metal layer is formed on the surface of the positive electrode current collector. The injection of the valve metal by the blast device is preferably performed at an injection speed of 80 m / sec or more, or an injection pressure of 0.3 MPa or more.

  When the valve metal particles are jetted at a high speed by the shot coating method, thermal energy is generated when colliding with the surface of the positive electrode current collector. At this time, since the valve metal particles are heated on the surface of the positive electrode current collector, the valve metal particles are softened and deformed and fused to the surface of the positive electrode current collector. As a result, a film having high strength and firmly attached to the surface is formed.

  Since this energy conversion is performed only at the deformed portion where the shot material collides, the temperature rises locally near the surface of the shot material and the processed product.

A metal ring 109 is provided on the upper part of the outer wall of the concave container, and a bonding material is disposed on the upper surface of the metal ring 109. A bonding material is also disposed on the surface of the lid 102. The container 101 is sealed with a lid 102, and the concave container 101 and the lid 102 are joined by welding. The negative electrode active material 107 is attached to the lid 102 with a conductive adhesive 1112. When a conductive material is used for the lid 102, the lid 102 and the conductive adhesive 1112 function as a negative electrode current collector. When a non-conductive material is used for the lid 102, the conductive adhesive 1112 that electrically connects the conductive adhesive 1112 and the connection terminal B 1042 acts as a negative electrode current collector. A negative electrode is formed by the negative electrode active material 107 and the negative electrode current collector. In addition, the positive electrode active material 106 and the negative electrode active material 107 are separated by the separator 105.

  The valve metal layer 103 may be provided directly on the positive electrode current collector 103 by a shot coating method, or another metal may exist between the positive electrode current collector 103 and the valve metal layer 112. After the electric body is plated with gold or nickel, it may be further covered with the valve metal layer 112.

  Next, FIG. 2 shows a cross-sectional view of another electrochemical cell according to the present invention. When the container 101 is made of alumina, a square alumina green sheet serving as a bottom surface is provided, a tungsten print is applied to the surface, and wiring of the positive electrode current collector 103, the connection terminal A1041, and the connection terminal B1042 is provided. Next, a second square alumina green sheet having a circular hole in the center is disposed. Thereby, the area which the positive electrode electrical power collector has exposed can be made small. A part of the positive electrode current collector 103 is embedded in the container 101, and the remaining part of the positive electrode current collector is exposed. Further, an alumina green sheet serving as the outer wall of the container 101 is disposed. When this state is viewed from the top, it becomes as shown in FIG. 3, and the exposed area of the positive electrode current collector 103 is smaller than the area of the container bottom surface 1011. At this time, the positive electrode current collector 103 does not need to have the same shape as the hole of the second square alumina green sheet. The shape of the positive electrode current collector 103 may be any shape that allows electrical contact with the valve metal layer 112. For example, it may be a line or a band. Further, the shape of the hole of the second square alumina green sheet does not need to be circular. What is necessary is just to be smaller than the area of the container bottom face 1011.

  When a portion of the positive electrode current collector is embedded in the container, the portion covered with the positive electrode current collector becomes small, and it is less likely that film defects such as pinholes in the valve metal layer 112 will be directly affected. Reliability was also improved. When the positive electrode current collector is on the entire bottom surface of the container, it is difficult to cover the positive electrode current collector near the outer wall of the container, and if the position of the valve metal layer is slightly shifted, a part of the positive electrode current collector is exposed or a metal ring or Although it may come into contact with the bonding material and may cause an internal short-circuit, it may not function. However, in the present invention, even if the formation position of the valve metal layer is slightly shifted, part of the positive electrode current collector is exposed or metal It can be easily covered without contact with the ring or the bonding material.

By using ceramics for the container, the heat resistance of the electrochemical cell is improved, and even if reflow soldering is performed, the characteristics of the electrochemical cell are not deteriorated and the reliability is improved. Zirconia and alumina can be used. Alumina is advantageous in terms of cost and has almost no humidity ingress through the container, so that the reliability under humidity storage is remarkably improved.

  Next, as shown in FIG. 4, a metal mask 113 having protrusions with square holes in the metal plate was placed on the upper surface of the container 101 so that the protrusions faced downward. When shot coating is performed from above in FIG. 4, the valve metal layer 112 made of the valve metal can be formed only on the bottom surface. Since the valve metal layer is not connected to the metal ring 109 or the bonding material, a short circuit in the electrochemical cell can be prevented. The positive electrode current collector 103 and the positive electrode active material 106 are electrically connected through the valve metal layer 112.

  Next, the remaining wiring of the connection terminal A1041 and the connection terminal B1042 was disposed on the outer wall of the container 101, and then fired to obtain the container 101. A metal ring 109 was further joined to the container 101.

  The valve metal layer 112 was disposed on the surface of the positive electrode current collector 103. FIG. 5 shows a state in which this state is viewed obliquely from above.

  On the positive electrode side, the valve metal layer 112 may be smaller than the positive electrode active material 106. If the conductive adhesive 1111 is applied to approximately the same size as the positive electrode active material 106, the flow of electrons between the electrode active material and the current collector is not hindered, and the internal resistance of the electrochemical cell is increased. There is no deterioration of the characteristics.

  Further, the positive electrode current collector and the positive electrode active material 106 do not need to be particularly bonded, and the conductive adhesive 1111 may be simply applied on the bottom of the concave container 101 and then placed on the top. The lid 102 and the negative electrode active material 107 were bonded in advance with a conductive adhesive 1112 containing carbon.

  The metal ring 109 is electrically connected to the connection terminal B1042.

  The portion of the lid 102 on the container side was subjected to nickel plating as a bonding material.

  The positive and negative electrodes, the separator 105, and the electrolyte 108 were housed inside the container, covered with the lid 102, and then welded on two opposite sides of the lid 102 by a parallel seam welding machine using the principle of resistance welding. By this method, highly reliable sealing was obtained.

  The valve metal layer 112 is preferably smaller than the concave container bottom surface 1011. If the valve metal layer 112 is too large, the conductor adheres to the inside of the outer wall of the concave container 101, causing contact with the metal ring 109, the bonding material on the metal ring, or contact between the electrode active materials. Cause short circuit.

  The container 101 is made of ceramics, and high strength, insulating ceramics such as alumina and zirconia can be used. As a processing method, a method in which green sheets punched into a predetermined shape are stacked and fired is also effective in forming the positive electrode current collector 103, the connection terminal A1041, and the connection terminal B1042.

  The positive electrode current collector 103, the connection terminal A1041, and the connection terminal B1042 can be manufactured by wiring and wiring with a tungsten print containing tungsten powder. Since it has a structure that penetrates a part of the concave container 101 like the positive electrode current collector 103, it is necessary to wire before firing the green sheet. The material is also limited to refractory metals such as tungsten and molybdenum.

  The shot coating method is a method disclosed in the literature “Ceramics 37, 2002, No. 1, P46-P48” and the like. It was found that various advantages can be exhibited when used in the electrochemical cell of the present invention as compared with other film forming methods. For example, vapor deposition, sputtering, and CVD can provide a dense film, but the apparatus is large and the film formation rate is slow. In the thermal spraying, there is a problem that the film forming speed is high but the film becomes porous and cheap, so that it is not suitable for electrochemical cells unless it is thick to some extent. The shot coating method means impact film formation. When a soft metal powder such as aluminum is sprayed at a high speed onto the surface of ceramics or the like, the kinetic energy of the spray is instantaneously converted into heat to form a film.

  Aluminum, tantalum, niobium, titanium, hafnium, or zirconium can be used as the valve metal of the valve metal layer to be coated by the shot coating method. Use of these metals can withstand the high potential of the positive electrode, and has the effect of improving the performance and storage characteristics of the electrochemical cell.

  Among valve metals, aluminum is particularly excellent in performance and cost. It is easy to obtain and the film itself is easy to make. In the shot coating method, a film could be stably formed by hitting aluminum particles having an average particle diameter of 4 to 20 μm at a speed of 100 to 400 m / s.

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

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

  For the positive electrode current collector 103 and the connection terminal A 1041 and the connection terminal B 1042, nickel, gold, tin, and solder layers are preferably provided for soldering to the base. It is preferable to provide a layer of nickel, gold, or the like that is compatible with the bonding material at the edge of the concave container 101. Examples of the layer forming method include vapor phase methods such as plating and vapor deposition.

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

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

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

  The joint can be welded by seam welding using resistance welding. After the lid 102 and the container 101 are spot welded and temporarily fixed, welding is performed according to the principle of resistance welding by pressing a roller-type electrode facing two opposite sides of the lid 102 and passing an electric current. Sealing can be performed by welding the four sides of the lid 102. Since the current flows in a pulsed manner while rotating the roller electrode, it becomes a seam shape after welding. If the pulse width is not controlled so that individual weld marks by the pulses overlap, complete sealing cannot be achieved.

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

  As the electrolyte according to the present invention, a liquid, a solid, or a gel can be used.

  Organic solvents used for liquid and gel electrolytes are acetonitrile, diethyl ether, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, propylene carbonate (PC), ethylene carbonate (EC), γ- Butyrolactone (γBL) or the like can be used.

The supporting salts contained in the liquid and gel electrolytes are (C ₂ H ₅ ) ₄ PBF ₄ , (C ₃ H ₇ ) ₄ PBF ₄ , (CH ₃ ) (C ₂ H ₅ ) ₃ NBF ₄ , (C ₂ H ₅ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ PPF ₆ , (C ₂ H ₅ ) ₄ PCF ₃ SO ₄ , (C ₂ H ₅ ) ₄ NPF ₆ , lithium perchlorate (LiClO ₄ ), 6 Lithium phosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO _{2) 2],} thiocyanate, aluminum fluoride salt, and the like can be used lithium salts, not limited thereto.

  The gel electrolyte is obtained by impregnating a polymer gel with a liquid electrolyte. Polyethylene oxide, polymethyl methacrylate, and polyvinylidene fluoride are suitable as the polymer gel, but are not limited thereto.

  The shape of the electrochemical cell of the present invention is basically free. The shape of a conventional electrochemical cell by caulking is limited to a substantially circular shape. For this reason, when trying to arrange them on the same substrate as other electronic components that are almost square, dead space is inevitably wasted. The electrochemical cell of the present invention can be designed in a square shape and can be efficiently arranged on a substrate because there is no protrusion of a terminal or the like.

  Electric double layer capacitors to be Examples 1 to 4 were produced. The dimensions of the container 101 were 3 × 5 mm and the height was 0.5 mm. The thickness of the part which becomes the outer wall of the container 101 was 0.3 mm. The positive electrode current collector 103, the connection terminal A1041, and the connection terminal B1042 were wired by tungsten printing. The positive electrode current collector 103 was a circle having a diameter of 1.0 mm, and the area thereof was sufficiently smaller than the area of the concave container bottom surface 1011. At the upper part of the container 101, a metal ring 109 made of Kovar and having a thickness of 0.15 mm was previously joined with a metal brazing material. As a result, the height of the outer wall of the container 101 was 0.4 mm.

  The exposed metal portion of the container 101 was subjected to nickel plating and then gold plating.

  In forming the valve metal layer 112, as shown in the cross-sectional view of FIG. 4, a simple metal mask 113 (a shape opened squarely to match the concave container) is placed on the concave container 101 to change the conditions. Film formation was performed by shot coating. Aluminum was used for the valve metal. Comparative Example 1 and Examples 1 to 4 were produced by changing the particle size of aluminum used for shot coating.

  The lid 102 was a 2 × 4 mm, 0.15 mm thick Kovar plate plated with nickel.

As the positive electrode active material 106 and the negative electrode active material 107, an activated carbon sheet having a size of 2 × 4 mm and a thickness of 0.15 mm was used. The positive electrode active material 106 was bonded to the bottom of the container 101 with a conductive adhesive 1111. The negative electrode active material 107 was bonded to the lid 102 with a conductive adhesive 1112. Next, the separator 105 was placed on the positive electrode active material 106, and 5 μL of an electrolyte obtained by adding 1 mol / L of (C ₂ H ₅ ) ₄ NBF ₄ to propylene carbonate (PC) was added. The lid 102 to which the negative electrode active material 107 is bonded is covered, the lid 102 and the container 101 are spot-welded and temporarily fixed, and then a roller-type electrode facing two opposite sides of the lid 102 is pressed and a current is passed, thereby causing resistance. Seam welding was performed according to the welding principle.

  Shot coating was performed by spraying aluminum particles having an average particle diameter of 4 to 30 μm at a speed of 300 m / s using air as a carrier gas. An aluminum layer could be formed on the positive electrode current collector. The thickness of the aluminum layer that is the valve metal layer was 10 μm. Table 1 shows the internal resistance of the produced electric double layer capacitor.

アルミニウムの粒径においては小さいと内部抵抗が上がる傾向があった。これは、粒径が小さいとアルミニウム皮膜の表面に酸化皮膜ができやすいためと考えられる。内部抵抗の上限は使用する機器の特性にもよるが１５０Ω以下であれば実用上問題がない。このことより粒径は４μｍ以上の大きさが好ましい。

When the particle size of aluminum is small, the internal resistance tends to increase. This is considered because an oxide film is easily formed on the surface of the aluminum film when the particle size is small. Although the upper limit of the internal resistance depends on the characteristics of the equipment used, there is no practical problem if it is 150Ω or less. Accordingly, the particle size is preferably 4 μm or more.

In Comparative Example 2 and Examples 5 to 10, an experiment for examining an appropriate film thickness was performed. In Examples 5 to 10 and Comparative Example 2, aluminum particles having an average particle diameter of 10 μm were sprayed at a speed of 300 m / s using air as a carrier gas by a shot coating method, and the thickness of the aluminum layer as the valve metal layer was changed. Made. With respect to the completed electric double layer capacitor, a voltage of 2.5 V was applied at room temperature, and the leakage current after 24 hours was measured. In the case of an electric double layer capacitor of the size of the present embodiment, the leakage current is usually 2 μA or less, but if any reaction occurs in the cell, the leakage current increases and storage degradation also increases. Further, as a test for examining the accelerated storage deterioration of the electric double layer capacitor, the capacity retention rate after storage at 70 ° C., 2.5 V for 20 days was measured. This storage period is roughly equivalent to after storage for 2 years at room temperature, and it is said that there is no problem in practical use if the capacity is maintained at 70% or more.
The test results are shown in Table 2.

膜厚は５μｍ以上あれば実用上問題のない７０℃、２．５Ｖ、２０日保存後の容量維持
率が７０％以上となる。リーク電流も膜が厚いほど小さくなり、アルミニウムの欠陥により下地の集電体が溶解しにくくなっているものと考えられる。しかし、膜厚が厚くなるとセル内部の空間を狭くし活物質が入るスペースを圧迫するため、３０μｍ以下が好ましい。

If the film thickness is 5 μm or more, the capacity maintenance rate after storage at 70 ° C., 2.5 V, 20 days, which has no practical problem, is 70% or more. It is considered that the leak current also decreases as the film becomes thicker, and the underlying current collector is less likely to dissolve due to aluminum defects. However, when the film thickness is increased, the space inside the cell is narrowed and the space into which the active material enters is pressed.

Further, the particle spraying speed was preferably 100 to 400 m / s in order to accurately produce a film thickness of 5 to 30 μm. When the speed is 100 m / s or less, a dense film cannot be formed, and when a capacitor is formed, there is a tendency that leakage current increases and storage stability is deteriorated. In the case of 400 m / s or more, the source pressure of the carrier gas to be sprayed must be considerably increased, and the control of the film thickness becomes difficult, which is not practical for the electrochemical cell application of the present invention.
In this example, air was used as the carrier gas. As the carrier gas, an inability gas such as nitrogen or argon or carbon dioxide can be used. When an inert gas was used, oxidation of the aluminum film could be prevented, which was good. The carrier gas is preferably air from the viewpoint of cost and work safety.

  The electrochemical cell of the present invention has been able to obtain high reliability in storage by examining the shape and material of the current collector on the positive electrode side. It is particularly suitable for memory backup and other uses because it is highly resistant to storage when voltage is applied.

101 Container 1011 Container Bottom 102 Lid 103 Positive Current Collector 1041 Connection Terminal A
1042 Connection terminal B
105 Separator 106 Cathode Active Material 107 Anode Active Material 108 Electrolyte 109 Metal Ring 1111 Conductive Adhesive 1112 Conductive Adhesive 112 Valve Metal Layer 113 Metal Mask

Claims (11)

A positive electrode active material, a negative electrode active material, a separator that separates the positive electrode active material and the negative electrode active material, an ion conductive electrolyte, the positive electrode active material, the negative electrode active material, the separator, and the electrolyte are accommodated. An electrochemical cell comprising a concave container and a lid for sealing the container,
The bottom surface of the container is between a positive electrode current collector connected to a connection terminal and the positive electrode active material,
The electrochemical cell, wherein the positive electrode active material and the positive electrode current collector are electrically connected through a hole in the bottom surface.   The electrochemical cell according to claim 1, wherein the hole is covered with a valve metal layer. The electrolyte is liquid or gel,
The electrochemical cell according to claim 2, wherein the valve metal layer has few film defects to such an extent that the positive electrode current collector is not dissolved.   The electrochemical cell according to any one of claims 1 to 3, wherein the valve metal layer is formed by a shot coating method.   The electrochemical cell according to any one of claims 1 to 4, wherein the valve metal layer includes any one of aluminum, tantalum, niobium, titanium, hafnium, and zirconium.   The electrochemical cell according to claim 1, wherein the container is made of ceramics.   The electrochemical cell according to any one of claims 1 to 6, wherein the hole is located at the center of the bottom surface of the container.   The electrochemical cell according to any one of claims 1 to 7, wherein the positive electrode current collector has a linear shape or a strip shape. A first step of disposing a first alumina green sheet to be a bottom surface;
A second step of wiring a current collector and a connection terminal to the first alumina green sheet;
A third step of arranging a second alumina green sheet with a hole, and further forming an outer wall to produce a container;
Storing a positive electrode active material, a separator, a negative electrode active material, and a liquid or gel electrolyte in the container, and welding and sealing the lid and the container;
A method for producing an electrochemical cell comprising:   A step of forming a valve metal layer by a shot coating method using any of aluminum, tantalum, niobium, titanium, hafnium, and zirconium on the current collector provided at the bottom of the container after the third step. The method for producing an electrochemical cell according to claim 9, comprising:   11. The electricity according to claim 10, wherein the step of forming the valve metal layer is a step of forming the valve metal layer by a shot coating method in which aluminum particles having an average particle diameter of 4 to 20 [mu] m collide at a speed of 100 to 400 m / s. Chemical cell manufacturing method.

Images