JP4965809B2 - Electrochemical cell and method for producing electrochemical cell - Google Patents

Description

  The present invention relates to an electrochemical cell sealed by laser welding and a method for producing the electrochemical cell.

  In manufacturing an electrochemical cell, it is necessary to hermetically seal a container containing a separator, an electrode, and an electrolytic solution.

  In the conventional method of manufacturing an electrochemical cell, a metal lid is placed on the entire circumference of the upper surface of the container in order to hermetically seal the container containing the separator, electrode, and electrolyte. The sealing part was sealed by laser welding.

FIG. 7 shows a conventional method for producing an electrochemical cell. First, a base member 71 in which a metal frame member 72 is formed over the entire circumference of the upper surface accommodates a separator, an electrode, and an electrolyte solution ( not shown), and a metal cover member 73 is placed on the sealing portion 79. Next, the sealing part 79 was irradiated with the laser 301, and the cover member 73 or the frame member 72 was melted and joined (for example, refer patent document 1).
Japanese Unexamined Patent Publication No. 2004-153080 (page 3, FIG. 1)

  In the electrochemical cell and the manufacturing method thereof as described above, the electrolyte is mixed into the molten pool formed on the surface where the cover member and the frame member are in contact during welding, and the electrolyte is vaporized when the molten pool solidifies. There was a problem that a pinhole was opened and sealing could not be performed reliably.

  The present invention is intended to solve the problems of such a conventional method for producing an electrochemical cell, and prevents the electrolyte from entering the molten cover member and frame member, and seals the welded portion. The purpose is to stop.

The present invention includes a base member for accommodating the pair of electrodes facing each other via a separator and the separator is impregnated in the separator and the pair of electrodes, and an electrolyte solution filled into the base member over the upper surface entire periphery of the base member a frame member provided, a step of accommodating the cover and the member, a method for producing an electrochemical cell having a separator electrolytic solution is impregnated in the base member and a pair of electrodes to be joined to the frame member upper surface, the base a step of injecting an electrolyte solution in member, a step of placing the cover member on the upper surface of the frame member, a step of heating the frame member or cover member, a laser sealing section frame member and the cover member is in contact And a step of melting and joining the frame member and the cover member of the sealing portion.

In addition, the base member that houses the separator and the first electrode provided on one surface of the separator, the frame member provided over the entire upper surface of the base member, and the upper surface of the frame member are joined to each other and the first surface is joined to the first surface. a cover member having a second electrode, a separator and impregnated with a first electrode and a second electrode, and method for producing an electrochemical cell having an electrolyte solution is filled into the base member, the electrolyte on the base member liquid is accommodated a separator impregnated and the first electrode, placing a step of injecting an electrolyte solution, the upper surface of the frame member, the second electrode electrolytic solution is impregnated a cover member so as to be in contact with the separator A step of heating the frame member or the cover member, a step of irradiating the sealing portion where the frame member and the cover member are in contact with each other, a frame member and a cover of the sealing portion

A step of melting and melting the members.

  Further, in the step of heating the frame member or the cover member, a heating electrode connected to a power source is connected to the frame member or the cover member, and the frame member is heated by applying a current to the heating electrode.

Further, in the step of heating the frame member or the cover member, the temperature of the frame member or the cover member is monitored, and when the boiling point of the electrolytic solution is reached, the sealing portion is irradiated with a laser.

  Further, in the step of heating the frame member or the cover member, the step of applying a voltage to the frame member or the cover member and the step of measuring the rate of change of current caused by the application of the voltage are alternately performed a plurality of times.

  The frame member is selected from any of an alloy of iron and nickel, an alloy of iron, nickel and cobalt, stainless steel, and an aluminum alloy.

Further, a base member for accommodating a pair of electrodes opposing each other via a separator and the separator is impregnated in the separator and the pair of electrodes, and an electrolyte solution filled into the base member, a frame that is provided over the upper surface entire periphery of the base member A member, a cover member joined to the upper surface of the frame member, and a sealing portion in which the frame member and the cover member heated and melted by a heating electrode and a laser are welded to a surface where the cover member and the frame member are in contact with each other Have

  Moreover, a frame member has the electroconductive terminal heated with the electrode for a heating on the side surface of a frame member.

Moreover, it is the sealing part heated and welded until the sealing part reached the boiling point of electrolyte solution .

  In the method for producing an electrochemical cell of the present invention, the sealing member is heated to a temperature equal to or higher than the boiling point of the electrolytic solution to keep the electrolytic solution in a gas state near the sealing portion. The electrolytic solution is prevented from entering the molten pool formed on the contacting surface, and no pinhole is generated in the sealing portion.

  Furthermore, the temperature of the sealing portion is kept below the heat resistance temperature of the joint portion between the base member and the frame member and the heat resistance temperature of the base member. As a result, the joint portion between the base member and the frame member and the base member are prevented from exceeding the respective heat resistance temperatures, and the joint between the base member and the frame member is impaired, or the frame member and the cover member are not damaged. Join.

  By maintaining the above-described temperature, the frame member and the cover member are reliably bonded without impairing the bonding strength between the base member and the frame member, so that the effect of improving the sealing degree of the electrochemical cell is exhibited. is there.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a plan view of an electrochemical cell in Example 1 of the present invention.

  A container that contains a separator 7, electrodes 8 a and 8 b, and an electrolytic solution 6, and a cover member via a frame member 4 that is provided over the entire circumference of the upper surface of the base member on the base member 1 in which the conductive terminals 5 are integrally formed. 3 is joined.

  The base member 1 is made of insulating resin or ceramic. When using resins, thermosetting resins with heat resistance such as epoxy and polyimide, and thermoplastics such as polystyrene, polyphenylene sulfide, polyester, polyamide, and polyether are suitable from the viewpoint of rigidity and heat resistance. ing. Here, syndiotactic polystyrene is used as the polystyrene system, linear and cross-linked polyphenylene sulfide is used as the polyphenylene sulfide system, wholly aromatic polyester is called liquid crystal polymer as the polyester system, nylon is used as the polyamide system, and polyether is used as the polyether system Polyether ether ketone, polyether sulfone, polyether imide, etc. are used. Further, those obtained by adding glass fiber, mica, ceramic fine powder, etc. to these resins are also used. Also, when using ceramics, alumina, zirconia, etc. are suitable.

  The material of the frame member 2 and the cover member 3 is selected from metal materials having high thermal conductivity or high resistance, and preferably FeNi alloy, FeNiCo alloy, stainless steel, or aluminum alloy is used.

  As a bonding material between the base member 1 and the frame member 2, a metal brazing material such as silver or tin, an organic compound adhesive such as epoxy, or an inorganic brazing material is used according to the material of the base member or the frame member.

  As a power generation element of the electrochemical cell accommodated in the container, if it is a nonaqueous electrolyte battery, lithium-containing manganese oxide, lithium-containing cobalt oxide, lithium-containing titanium oxide as the positive electrode active material, carbon, lithium as the negative electrode active material Conventionally known materials such as alloys, transition metal oxides and silicon oxides can be used. In the electric double layer capacitor, activated carbon can be used for the positive electrode and the negative electrode active material.

  As the separator, an insulating film having a large ion permeability and a predetermined mechanical strength is used. Considering mounting in a reflow furnace, glass fibers can be used stably, but resins such as polyphenylene sulfide, polyethylene terephthalate, polyamide, and polyimide can also be used. The pore diameter and thickness of the separator are not particularly limited, but are design matters determined based on the current value of the equipment used and the internal resistance of the electrochemical cell. A ceramic porous body can also be used.

  As the solvent for the electrolytic solution, when an electric double layer capacitor or a non-aqueous secondary battery is taken as an example, a conventional non-aqueous solvent is used. This non-aqueous solvent includes cyclic esters, chain esters, cyclic ethers, chain ethers, and the like. Considering reflow mounting, it can be used alone or in combination selected from γ-butyrolactone (γBL), propylene carbonate (PC), ethylene carbonate (EC), and the like.

As 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 hexafluoroarsenide (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ], thiocyanate One or more salts such as lithium salt such as aluminum fluoride and the like can be used. Polyethylene oxide derivatives or polymers containing polyethylene oxide derivatives, polymers containing polypropylene oxide derivatives and polypropylene oxide derivatives, phosphate ester polymers, PVDF, etc., used in combination with nonaqueous solvents and supporting salts, including gel or solid use . Also it includes the use of an inorganic solid electrolyte _{LiS / SiS 2 / Li 4 SiO} 4. Also, pyridine-based, alicyclic amine-based, aliphatic amine-based ionic liquids and amidine-based room temperature molten salts may be used.
If these are used, it is effective in suppressing generation | occurrence | production of the vapor | steam at the time of welding with a cover member and a frame member.

  2 to 4 are cross-sectional views taken along the line A-A 'of FIG.

First, as shown to (a), the frame member 2 which has the conductive terminal 2a on the side surface is installed over the perimeter of the base member 1 upper surface. The base member 1 is filled with the separator 7 impregnated with the electrolytic solution 6, and the electrode 8 a installed on one surface of the separator 7 is accommodated, and further filled with the electrolytic solution 6. Next, as shown in (b), the cover member 3 having the electrode 8b on one surface is placed on the upper surface of the frame member 4 so that the electrode 8b is in contact with the separator 7.

Next, as shown in (c), heating electrodes 201a and 201b connected to a power source 200 having a voltage applying means (not shown) and a current measuring means (not shown) are connected to the conductive terminal 5 . Connect to the tip 5a . First, a pulse voltage is applied from the heating electrodes 201a and 201b to the conductive terminal 5 for a certain period of time. In this embodiment, application was performed for 30 msec. Thus, the frame member 2 is heated via the conductive terminal 2 by applying a current to the heating electrodes 201a and 201b. Next, the rate of change in resistance value caused by the application of a pulse voltage is measured with the heating electrodes 201a and 201b. By measuring the resistance value in this way, the temperature of the frame member 2 is monitored. Until the measured temperature reaches the boiling point of the electrolytic solution 6, the step of applying this voltage and the step of measuring the current are alternately repeated, and the temperature of the sealing portion 9 where the frame member 2 and the base member 1 are in contact is monitored. While heating.

FIG. 4 is a graph showing a temperature monitoring method by voltage application and current measurement. At t1, a pulse voltage P1 is applied from the heating electrodes 201a and 201b. When the voltage is applied for a certain time d, the resistance value is measured by the heating electrodes 201a and 201b at t2, and the temperature of the frame member 2 is monitored. Since the measured temperature of the frame member 2 has not reached the boiling point T of the electrolytic solution 6, the pulse voltage P3 is applied again at t3. Until it reaches the boiling point T of the electrolyte 6, repeated measurements of the applied current voltage, to end the application of the voltage reaches the boiling point T of the electrolyte 6 t8 by a pulse voltage P4 at t7. Welding is performed within a time A in which the frame member 2 is equal to or higher than the boiling point T.

When the temperature of the sealing portion 9 reaches the boiling point T of the electrolytic solution 6 by heating the frame member 2, the entire periphery of the frame member 2 is irradiated with the laser beam 301 on the sealing portion 9 as shown in (d), The frame member 2 and the cover member 3 are melted and welded.

On the surface where the frame member 2 and the cover member 3 are in contact with each other, the electrolyte solution 6 is in a dry state. Therefore, the electrolytic solution 6 does not enter the molten pool generated in the frame member 2 and the cover member 3 by laser irradiation. Therefore, no pinhole is generated in the sealing portion 9. The electrolytic solution 6 is prevented from leaking to the outside of the container, and also the entrance of humidity from the outside of the container is prevented, thereby improving the reliability of the electrochemical cell.

  5 and 6 are cross-sectional views of an electrochemical cell showing a method for producing an electrochemical cell in Example 2 of the present invention.

First, as shown to (a), the frame member which has the conductive terminal 2 in the side surface is installed over the perimeter of the base member 1 upper surface. The base member 1 is filled with the separator 7 impregnated with the electrolytic solution 6 and the pair of electrodes 8 a and 8 b disposed to face each other with the separator 7 interposed therebetween, and further filled with the electrolytic solution 6.

  Next, the cover member 3 is placed on the upper surface of the frame member 2 as shown in FIG.

Next, as shown in (c), the heating electrodes 201a and 201b connected to the power source 200 having the voltage applying means and the current measuring means are connected to the cover member 3 . First, a pulse voltage is applied to the cover member 3 from the heating electrodes 201a and 201b for a predetermined time. Thus, a current is applied to the heating electrodes 201a and 201b to heat the cover member 3 . Next, the rate of change of current generated by applying the pulse voltage is measured with the heating electrodes 201a and 201b. By measuring the current in this way, the temperature of the cover member 3 is measured. Until the measured temperature reaches the boiling point of the electrolytic solution 6 , the step of applying this voltage and the step of measuring the current are alternately repeated, and the temperature of the sealing portion 9 where the frame member 2 and the base member 1 are in contact is monitored. While heating.

When the temperature of the sealing part 9 reaches the boiling point of the electrolytic solution 6 by heating the frame member 2, the sealing part 9 is irradiated with laser light 301 as shown in (d), and the frame member 2 and the cover member 3 are moved. Melt and weld.

  In heating the cover member, it is also useful to keep the temperature below the heat resistance temperature of the bonding material for bonding the base member and the frame member. By repeating heating of the cover member and temperature monitoring, there is an effect of preventing excessive heating until the bonding between the base member and the frame member is impaired.

  The method for producing an electrochemical cell described above can be carried out using other materials or conditions, and is not limited to the example shown in Example 1 or 2.

The figure which shows the electrochemical cell in Example 1 The figure in which the electrification in Example 1 shows the manufacturing method of a cell The figure in which the electrification in Example 1 shows the manufacturing method of a cell The figure which showed the value of the voltage and electric current which electrification in Example 1 applies to a cell The figure in which the electrification in Example 2 shows the manufacturing method of a cell The figure in which the electrification in Example 2 shows the manufacturing method of a cell The figure which shows the manufacturing method of the cell by the conventional electrification

DESCRIPTION OF SYMBOLS 1 Base member 2 Frame member 5 Conductive terminal 3 Cover member 6 Electrolyte solution 7 Separator 8 Electrode 9 Sealing part 200 Power supply 201 Heating electrode 301 Laser beam

Claims (4)

An electrochemical cell comprising: a base member that houses a power generation element; an electrolyte that fills the base member; a frame member that is provided over the entire upper surface of the base member; and a cover member that is joined to the upper surface of the frame member. A manufacturing method of
Storing the power generation element in the base member, injecting the electrolyte into the base member, and placing the cover member on the upper surface of the frame member;
The temperature of the sealing portion where the frame member and the cover member are in contact is equal to or higher than the boiling point of the electrolyte solution and equal to or lower than the heat resistant temperature of the joint between the base member and the frame member and the heat resistant temperature of the base member. Heating the frame member or the cover member by applying an electric current;
Monitoring the temperature of the sealing part, and irradiating the sealing part with a laser when the sealing part is heated to a boiling point of the electrolyte or higher, melting the sealing part, and performing bonding; and ,
The manufacturing method of the electrochemical cell which has this.   The method for manufacturing an electrochemical cell according to claim 1, wherein a heating electrode connected to a power source is connected to the frame member, and the sealing portion is heated by applying a current to the heating electrode.   The method for producing an electrochemical cell according to claim 1 or 2, wherein a heating electrode connected to a power source is connected to the cover member, and the sealing portion is heated by applying a current to the heating electrode.   The method for producing an electrochemical cell according to any one of claims 1 to 3, wherein the frame member is selected from an alloy of iron and nickel, an alloy of iron, nickel and cobalt, stainless steel, and an aluminum alloy.

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