JP4845388B2 - Electrochemical cell - Google Patents

Description

  The present invention relates to an electrochemical cell.

  Electrochemical cells such as non-aqueous electrolyte secondary batteries and electric double layer capacitors are characterized by high energy density, light weight, and small size, and have been used as backup power sources for clock functions of portable devices and backup power sources for semiconductor memories. It was. These portable devices need to be reduced in size, weight, and functionality, and further high-density mounting of electrochemical cells is required.

  Further, a reflow soldering method is generally used when an electrochemical cell is mounted on a circuit board. In the reflow soldering method, a solder cream is applied to a part to be soldered on a circuit board, an electrochemical cell is placed thereon, and the whole circuit board is passed through a high-temperature furnace at 200 to 260 ° C. It is a method of attaching. Electrochemical cells are required to have high heat resistance so that they can withstand reflow soldering.

  In order to improve the sealing strength, an electrochemical cell has been developed that welds and seals a container and a lid (see, for example, Patent Document 1). This electrochemical cell has high sealing strength and excellent heat resistance because the container and the lid are joined by resistance welding or the like.

In addition, in an electronic component having a bipolar external electrode having a polarity such as a positive electrode and a negative electrode, there has been a technique for making the polarity constant even when the electronic component is mounted on a circuit in the reverse direction (for example, Patent Literature 2). In the invention disclosed in Patent Document 2, two positive electrode connection terminals and two negative electrode connection terminals are provided, and the positive electrode connection terminal and the negative electrode connection terminal are arranged at symmetrical positions, so that there are 180 electrochemical cells. On the other hand, a technique is disclosed in which the polarity is constant even when mounted on a circuit board.
JP-A-2001-216952 (2nd to 3rd terms, Fig. 1) Japanese Patent Laid-Open No. 2000-150304 (2nd to 3rd terms, FIGS. 1 to 4)

  The problem of the present invention is that the electrode has polarity, so that if the electrochemical cell is mounted 180 degrees opposite to the circuit, corrosion occurs inside the electrochemical cell and the soldering strength between the electrochemical cell and the circuit board is weak. .

  In the electrochemical cell sealed by welding the container and the lid, the welded portion is vulnerable to corrosion. For this reason, an electrochemical cell is made so that the weld is on the negative electrode side. The positive electrode side is easily corroded because electrons are taken and oxidized during charging of the electrochemical cell. On the other hand, the negative electrode side is unlikely to corrode because electrons are received and reduced during charging. When the electrochemical cell is mounted on the circuit board on the opposite side by 180 degrees and the connection terminals are connected in reverse, the positive and negative electrodes of the electrochemical cell are reversed. Originally, the weld that should be on the negative electrode side becomes the positive electrode side and is anodized to cause corrosion. For this reason, as disclosed in Patent Document 2, there is a demand for an electrochemical cell having a constant polarity even when mounted on a circuit in the reverse direction.

  However, the invention disclosed in Patent Document 2 has weak soldering strength between the electrochemical cell and the circuit board. The electrochemical cell is soldered to the circuit board by reflow soldering. However, since the connection terminal is provided at the center of one side of the electrochemical cell in the invention of Patent Document 2, there are only two surfaces to which the solder is joined. .

  An object of the present invention is to provide an electrochemical cell having a constant polarity and a high soldering strength even when mounted on a circuit board in the opposite direction of 180 degrees.

  The electrochemical cell of the present invention comprises a pair of positive terminals formed at the corners on the same diagonal line of the bottom surface and a pair of negative terminals formed at the corners on the diagonal line different from the positive electrode terminals.

  The electrochemical cell of the present invention includes a container, a lid, a positive electrode placed on the bottom side of the container, a separator placed on the positive electrode, a negative electrode placed on the separator, and an electrolysis The container and the lid are sealed via a welded portion, and a pair of positive terminals formed at corners on the same diagonal line on the bottom of the container are different from the positive terminals A pair of negative electrode terminals formed at corners on a diagonal line is formed.

  The electrochemical cell of the present invention includes a container, a lid, a positive electrode placed on the bottom surface side of the container, a separator placed on the positive electrode, and a negative electrode placed on the separator. A pair of positive electrode terminals formed at the corners on the same diagonal line on the bottom surface of the container, and the positive electrode terminals A pair of negative electrode terminals formed at corners on a diagonal line different from the above are formed, and the negative electrode terminal and the welded portion are electrically connected.

  In the electrochemical cell of the present invention, a positive electrode terminal and a negative electrode terminal are formed at corners of the bottom surface, the positive electrode terminal includes a first positive electrode terminal and a second positive electrode terminal, and the negative electrode terminal is a first negative electrode. A terminal and a second negative electrode terminal, the first positive electrode terminal and the second positive electrode terminal are located symmetrically across the center point of the bottom surface of the electrochemical cell, and the center point of the bottom surface of the electrochemical cell is The first negative terminal and the second negative terminal are positioned symmetrically with respect to each other.

  In the electrochemical cell of the present invention, a pair of positive electrode terminals and a pair of negative electrode terminals are formed at the corners of the bottom surface on the bottom surface, and the positive electrode terminals and the negative electrode terminals are alternately arranged.

  When the present invention is used, since the positive electrode connection terminal and the negative electrode connection terminal are arranged in a symmetrical position, the polarity is constant even when the electrochemical cell is mounted on the circuit board by 180 degrees. For this reason, the welded portion is always on the negative electrode side, and corrosion does not occur inside the electrochemical cell.

  Furthermore, in the present invention, since the connection terminals are arranged at the corners, the circuit board is soldered at the bottom surface and the two side surfaces, so that the soldering strength is increased.

A bottom view of the electrochemical cell according to the present invention is shown in FIG. A pair of positive electrode terminal 2 and negative electrode terminal 3 is provided at each corner of the bottom surface of the electrochemical cell.
A first positive electrode terminal 2a, a second positive electrode terminal 2b, a first negative electrode terminal 3a, and a second negative electrode terminal 3b are respectively provided at the corners of the electrochemical cell. The first positive electrode terminal 2a and the second positive electrode terminal 2b are formed on the same diagonal line on the bottom surface of the electrochemical cell. The first negative electrode terminal 3a and the second negative electrode terminal 3b are formed on a diagonal line different from the positive electrode terminal. Even if the electrochemical cell is mounted on the circuit board in the opposite direction of 180 degrees, the polarity of the terminal is not connected in the opposite direction.

  FIG. 2 is a cross-sectional view of a nonaqueous electrolyte secondary battery or an electric double layer capacitor according to the present invention. It is sectional drawing in the AB surface of FIG.

  Hereinafter, an example in which ceramic is used for the container 1 will be described. Containers 1 were formed by laminating green sheets. At that time, the container 1 having tungsten wiring was formed by printing tungsten on a green sheet and performing a sintering process. The tungsten wiring was covered with nickel or gold plating for corrosion prevention or soldering to form a positive terminal and a negative terminal.

  The first positive electrode terminal 2 a and the second positive electrode terminal 2 b are formed on the inner bottom surface of the container 1, penetrate the wall surface of the container 1, and are disposed to the outer bottom surface via the outer side surface of the container 1. The positive electrode 4 of the chemical cell and an external circuit are connected. Moreover, the positive electrode terminal formed on the inner bottom surface of the container 1 is in contact with the positive electrode 4 and also functions as a positive electrode current collector.

  The first negative electrode terminal 3a and the second negative electrode terminal 3b are disposed from the welded portion to the outer bottom surface along the outer corner of the container 1, and connect the negative electrode 6 of the electrochemical cell and an external circuit.

  A positive electrode 4 and a glass fiber separator 5 were laminated on the inner bottom surface of the container 1. Next, the electrolytic solution 7 was poured into the container 1. The electrolytic solution 7 is composed of a supporting salt and an organic solvent. As the organic solvent, a mixed solvent of a low viscosity solvent and a high dielectric constant solvent was used.

  Next, the negative electrode 6 was attached to the lid 8 with a conductive adhesive and dried. The lid 8 may be made of a conductive material or an insulating material. When an insulating material is used for the lid 8, a conductive film is formed on the surface of the lid 8 to which the negative electrode 6 is attached. The negative electrode 6 and the negative electrode terminal 3 are electrically connected, and the negative electrode 6 is connected to an external circuit through the negative electrode terminal.

  A bonding material 10 is provided at the end of the side wall of the container 1, and the bonding material 10 is melted to become a welded portion 9 to join the lid 8 and the container 1. Either one of the container 1 and the lid 8 or both the container and the lid may be provided as the bonding material.

  Although the welding method is not particularly limited for welding the container 1 and the lid 8, it is preferable to use resistance seam welding or laser seam welding because the sealing strength is increased and the heat resistance is improved.

  FIG. 3 shows a perspective view of the container and lid of the electrochemical cell according to the present invention.

  An electric double layer capacitor was produced using a storage container having the same shape as in FIG. The container 1 is made of alumina and has a size of 4 × 5 × 1 mm. A nickel plating layer is formed as a bonding material on the side wall end of the container 1, and the lid 8 and the container 1 are welded through the nickel plating layer. The concave dent was 0.6 mm in depth and 3 × 4 mm in size. The wiring of the positive electrode terminal and the negative electrode terminal was obtained by performing gold plating on tungsten. The positive electrode terminal is formed on the inner bottom surface of the container, passes through the wall surface of the container 1, and is disposed to the outer bottom surface through the outer side surface of the container 1. Also, tungsten and gold plating are arranged on the side surface of 1 to form a part of the positive electrode terminal. The 1st positive electrode terminal 2a and the 2nd positive electrode terminal 2b are provided in the two corner | angular parts located on the diagonal of a container bottom face.

  The first negative electrode terminal 3a and the second negative electrode terminal 3b are disposed from the welded portion to the outer bottom surface along the outer corner of the container 1, and connect the negative electrode of the electrochemical cell and an external circuit. Similar to the positive electrode terminal, in order to increase the contact area, the negative electrode terminal is made part of the negative electrode terminal by placing tungsten and gold plating on the side surface of the container where the solder rises. The positive terminal is provided at the remaining two corners on the bottom of the container.

The lid was an iron-cobalt alloy plate having a thickness of 0.15 mm. An iron-cobalt alloy is preferable because it has the same thermal expansion coefficient of alumina used in the container, and thus does not cause distortion or cracking even when heated and cooled. The positive electrode and the negative electrode had a size of 2 × 3 mm and a thickness of 0.15 mm, and activated carbon was compression molded using a fluororesin as a binder to obtain an electrode. The positive electrode was bonded to the bottom of the concave container 1 with a conductive adhesive. The negative electrode was bonded to the lid 8 with a conductive adhesive. Next, the separator was placed on the positive electrode, and an electrolytic solution in which 1 mol / L of (C ₂ H ₅ ) ₄ NBF ₄ was added to propylene carbonate (PC) was added. The lid 8 with the negative electrode adhered is placed on the container 1, and the lid 8 and the container 1 are spot welded and temporarily fixed, and then a roller-type electrode facing the opposite two sides of the lid 8 is pressed and an electric current is applied. The seam was welded by the principle of resistance welding.

  A non-aqueous electrolyte secondary battery was produced using the same container as in Example 1.

Commercially available MoO ₃ was pulverized, graphite as a conductive agent and polyacrylic acid as a binder were added and mixed to obtain a positive electrode active material. The mixing weight ratio of the positive electrode active material is MoO ₃ : graphite: polyacrylic acid = 53: 45: 2. Next, 5 mg of this positive electrode active material was pressure-molded at ² ton / cm ² to obtain a positive electrode. The positive electrode obtained with the conductive resin adhesive containing carbon was bonded to the container and integrated, and dried under reduced pressure at 250 ° C. for 8 hours.

A commercially available SiO crushed material was used as the negative electrode active material. To this active material, graphite as a conductive agent and polyacrylic acid as a binder were added and mixed to obtain a negative electrode active material. The mixing weight ratio of the negative electrode active material is SiO: graphite: polyacrylic acid = 45: 40: 15. A negative electrode was obtained by pressure-forming 1.1 mg of the negative electrode active material at ² ton / cm ² . The obtained negative electrode was bonded to the lid with a conductive resin adhesive and integrated, and then dried by heating under reduced pressure at 250 ° C. for 8 hours. The negative electrode and the lid are electrically connected, and the lid acts as a negative electrode current collector. Further, a lithium foil was pressure-bonded on the negative electrode. For the separator, a nonwoven fabric made of glass fiber having a thickness of 0.2 mm was used.

As the electrolytic solution, one obtained by dissolving 1 mol / L of lithium borofluoride (LiBF ₄ ) in a 1: 1 mixed solvent of ethylene carbonate (EC): γ-butyrolactone (γBL) was used.

  Cover the lid 8 with the negative electrode attached, spot weld the lid 8 and the container 1 in a nitrogen atmosphere, temporarily press the roller-type electrodes facing the two opposite sides of the lid 8 and pass an electric current. The seam was welded by the principle of resistance welding.

  When the lid 8 has conductivity, a metal such as iron-cobalt alloy, iron-nickel alloy, nickel, copper, stainless steel, or aluminum can be used. If the lid itself has conductivity, the lid can be used as a current collector for the negative electrode. Even if the lid itself is non-conductive, it can be used as a current collector if a conductive film is formed on the contact surface with the negative electrode.

  Although the material of the container 1 is not limited, it is preferable to use a heat-resistant material such as ceramic, glass, heat-resistant resin, or epoxy resin because the heat resistance of the electrochemical cell is improved. When resin is used for the container, insert molding of a metal terminal or the like is performed. As the resin used for the container, polyphenylene sulfide, polyethylene terephthalate, polyamide, polyimide, polyether ether ketone, liquid crystal polymer, and epoxy resin are suitable. By using a resin for the container, the container can be made at low cost. In the case of using a resin for the container, it is preferable that the same kind of resin used for the container is used for the lid, and the lid and the container are bonded or welded together to provide high sealing performance.

  In addition, when using resin for a container, a positive electrode terminal, a negative electrode terminal, a metal ring, and an epoxy resin are insert-molded, and the container 1 is formed. Metal plates are used as the positive terminal and the negative terminal. The negative electrode terminal and the metal ring are electrically connected. A metal ring is located at the end of the side wall of the container and is welded to the lid to seal the container.

  As the separator, an insulating film having a large ion permeability and a predetermined mechanical strength is used. In reflow soldering, glass fibers can be used most stably, but resins such as polyphenylene sulfide, polyethylene terephthalate, polyamide, polyimide having a heat distortion temperature of 230 ° C. or higher can also be used. The pore diameter and thickness of the separator are not particularly limited, and are design matters determined based on the current value of the device used and the internal resistance of the capacitor. A ceramic porous body can also be used.

As the supporting salt used in the electrolyte, (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 ), lithium hexafluorophosphate ( LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ], Thiocyanate, aluminum fluoride, lithium salt and the like can be used.

  As an organic solvent, acetonitrile, diethyl ether, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, propylene carbonate (PC), ethylene carbonate (EC), γ-butyrolactone (γBL), or the like may be used. it can.

It is a bottom view of the electrochemical cell of this invention. It is sectional drawing of the electrochemical cell of this invention. It is a perspective view of the container and lid | cover used for the electrochemical cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container 2 Positive electrode terminal 2a 1st positive electrode terminal 2b 2nd positive electrode terminal 3 Negative electrode terminal 3a 1st negative electrode terminal 3b 2nd negative electrode terminal 4 Positive electrode 5 Separator 6 Negative electrode 7 Electrolytic solution 8 Lid 9 Welding part 10 Joining material

Claims (7)

An electrochemical cell comprising a box-shaped container in which a power generation element is housed and a lid is sealed by welding via a welded portion,
At the four corners of the outer bottom surface of the box-shaped container, two positive terminals formed at diagonal corners and two negative terminals formed at other diagonal corners are disposed. It is,
The positive electrode terminal extends to the outer side corner of the box-shaped container, penetrates the wall surface of the box-shaped container, is formed on the bottom surface of the box-shaped container, and is electrically connected to the power generation element,
The negative terminal is extended along the outer side surface corner of the box-shaped container, the welded portion and electrically connected to have an electrochemical cell, wherein Rukoto. The electrochemical cell according to claim 1, wherein the lid has conductivity . The weld electrochemical cell according to claim 1, wherein the negative electrode der Rukoto. Said box-like container is made of a heat resistant material, electrochemical cell according to claim 1 wherein the positive electrode terminal and the negative terminal, wherein Rukoto such a metal. Wherein said negative terminal and positive terminal, electrochemical cell according to claim 4, wherein the tungsten Tona Rukoto. It said box-like container, the electrochemical cell according to claim 4, characterized in Rukoto a ceramic. The positive terminal and the negative terminal, an electrochemical cell according to claim 5, characterized that you have been coated with nickel plating or gold plating.

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