JP2007305306A - Coin type electrochemical element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coin type electrochemical element which is downsized and highly hermetic, which is capable of responding to a reflow process of a lead-free solder, and which is high in heat resistance, and its manufacturing method. <P>SOLUTION: Disc-like electrodes containing electrode active materials are oppositely arranged with a separator pinched, a frame-like gasket by nonconductive rubber is formed at the side face part of that electrode, an outer packaging material of directions of the upper and the lower faces of that electrode is formed by conductive rubber, and after injection of an electrolytic solution, the inner cell in which that conductive rubber and the nonconductive rubber are vulcanized and bonded and sealed is fabricated, and a contact part between the nonconductive rubber of the outer packaging side face of the laminated inner cell 12 and metallic coin cases (cap 11, case 14) and an insulating packing 13 is vulcanized and bonded by using a vulcanizing adhesive. Moreover, after caulking and sealing the metallic coin cases, rubber for outer packaging of the inner cell 12 is completely vulcanized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coin-type electrochemical element such as a coin-type battery and a coin-type electric double layer capacitor, and a method for manufacturing the same, and more particularly to a coin-type electrochemical element that is small in size and excellent in sealing properties and heat resistance and a method for manufacturing the same. .

  In recent years, in the power storage device, as a large product, a battery and an electric double layer capacitor are used as a battery for an automobile, and the market is expected to expand rapidly.

  On the other hand, as compact products, with the advent of the ubiquitous era, power consumption is expected to increase because new mobile electronic devices and cordless devices used indoors will increase, and the functionality of devices will increase due to technological advances. Along with this, the demand for batteries and electric double layer capacitors has increased, and the demand for improved energy density and miniaturization has become very strong. In particular, as backup devices are downsized, coin-type batteries, coin-type electric double-layer capacitors, coin-type proton polymer batteries, etc. are important as a common development issue, and the performance and utilization of electrode materials are important. Improvements in energy density, sealing technology, exterior efficiency, etc. are required by improving the rate. In addition, lead-free reflow is indispensable, and countermeasures against heat are an important issue.

  Conventionally, the exterior of a coin-type battery, a coin-type electric double layer capacitor, a coin-type proton polymer battery, etc., when the electrolytic solution is an alkaline solution or an organic solvent, A metal material that is extremely excellent in terms of conductivity and liquid barrier properties is used. However, when the electrolytic solution is an acid solution, the metal material corrodes except for some noble metals, and thus cannot be used as an exterior material. Therefore, when an acid solution is used as the electrolyte, an internal cell is produced using a conductive rubber in which carbon powder (carbon filler, etc.) is dispersed in a carbon material or rubber material, and it is caulked on a metal coin. The method is used.

  Incidentally, in order to increase the volume energy density, it is necessary to improve the exterior efficiency. To that end, it is required to make the members such as the current collector and the gasket as thin as possible. However, thinning the exterior leads to a decrease in sealing performance due to gas permeation, requires high dimensional accuracy in the manufacturing process, and there is a concern about a decrease in yield due to poor liquid leakage.

  As a technology for improving the sealing performance of coin-type batteries and coin-type electric double layer capacitors using non-aqueous electrolyte, a sealant is applied between the metal coin case and the resin packing. There are techniques such as Patent Document 1 and Patent Document 2 that improve sealing performance. FIG. 3 is a cross-sectional view of a coin-type battery according to the prior art, 11 is a metal coin case cap, 13 is a resin insulating packing, 14 is a metal bottomed cylindrical case, and 22 is a positive electrode. , 24 is a separator, 25 is a negative electrode, and 31 is a sealant.

  This technology can also be applied to a coin-type battery and a coin-type electric double layer capacitor using an aqueous electrolyte. In the case of water-based systems, it is also possible to improve the airtightness by adhering the contact area between the inner cell, the metallic coin case, and the resin packing with an adhesive, and using rubber, which is the exterior material of the inner cell, as a substitute for the sealing agent. It is done. However, when the rubber is bonded to the metal or resin with an adhesive, the physical properties are different, so that it is very difficult to bond and it is difficult to maintain good bonding over the long term. Furthermore, since it is necessary to use a heat-resistant adhesive to cope with lead-free reflow, there is a restriction that the selection range is narrowed.

JP 2000-11972 A JP 2000-348777 A

  As already explained in part, in coin-type batteries and coin-type electric double-layer capacitors that use an acid solution as the electrolyte, a conductive rubber in which carbon powder (carbon filler, etc.) is dispersed in a rubber material, An internal cell using conductive rubber as a current collector and a gasket, respectively, is produced, and it is caulked in a metal coin case. At this time, one of the methods for improving the energy density is to increase the exterior efficiency of the internal cell, and to make the exterior members such as the current collector and the gasket as thin as possible. However, reducing the thickness of the exterior reduces the gas permeation shielding and exterior strength, and reduces the sealing performance and yield.

  As a solution, a method of bonding the inner cell, the metal coin case, and the portion where the resin packing is in contact can be considered. Generally, when bonding rubber to metal or resin with an adhesive, each physical property is different. Very difficult to bond. Further, in order to cope with lead-free reflow, it is necessary to use a heat-resistant adhesive, so that the range of selection is narrowed, and it is difficult to perform sufficient adhesion to keep the coin tightness.

  Therefore, an object of the present invention is to provide a coin-type electrochemical device that is small in size, has high hermeticity, and has high heat resistance that can be used in a lead-free solder reflow process, and a method for manufacturing the same.

  In order to solve the above problems, in the present invention, conductive and non-conductive rubber is used for the exterior of the internal cell, and the non-conductive rubber on the exterior side of the internal cell contacts with the metal coin case and the resin packing. The parts are vulcanized and bonded using a vulcanizing adhesive. Further, after caulking and sealing the metal coin case, a process of vulcanizing the rubber that covers the inner cell is used.

  In the present invention, the contact portion between the rubber on the exterior side of the internal cell and the metal coin case and the resin packing is vulcanized and bonded using a vulcanized adhesive. , Long-term reliability, heat-resistant adhesion, and coin-type electrochemical with improved internal cell exterior reinforcement, yield, coin sealability, and lead-free reflow heat resistance despite its small size An element and a method for manufacturing the element can be provided.

  An embodiment of the present invention will be described with reference to the drawings, along with a method for manufacturing a coin-type proton polymer battery.

  As shown in the cross-sectional view of FIG. 1, the coin-type proton polymer battery is arranged in a state in which a plurality of internal cells 12 having a power storage function are singly or stacked in series (two in series are connected in series in FIG. 1). It is obtained by caulking and sealing with a metal-made bottomed cylindrical case 14 serving as a lower lid and a cap 11 serving as an upper lid through the insulating packing 13. At this time, the contact portion between the rubber on the exterior side surface of the internal cell 12, the metal coin case (cap 11 and case 14), and the resin packing (insulating packing 13) is vulcanized and bonded using the vulcanizing adhesive 15. As the vulcanized adhesive, a phenol resin or halogenated rubber is used, and a primer such as phenol resin or halogenated rubber is used to assist the adhesive force. The vulcanized adhesive may be applied to the rubber on the exterior side surface of the internal cell 12 or may be applied to a resin packing (insulating packing 13).

  As an example of the structure of the internal cell 12, as shown in a cross-sectional view in FIG. 2, a positive electrode 22 and a negative electrode 25 are arranged to face each other with a separator 24 therebetween, and an electrolyte solution that is an aqueous solution containing a proton source or a non-aqueous solution is provided for each. It exists in the electrode and in the separator 24. As the electrode active material contained in each electrode, a proton-conducting polymer that is appropriately selected in combination with a difference in redox potential capable of expressing the target electromotive force is used. And the circumference | surroundings are sealed with the electrical power collector 21 and the gasket 23, and the electrical power collector 21 has the function to take an electrical contact with each electrode and the exterior.

  The electrolytic solution is roughly classified into an organic solvent system and an aqueous solution system. In the proton polymer battery, since an aqueous solution containing a proton source has a particularly high capacity, an acidic aqueous solution is exclusively used. Therefore, a material having acid resistance is used for the current collector 21, the gasket 23, and the separator 24. For example, the current collector 21 is made of butyl rubber, elastomer or the like imparted with conductivity by adding carbon, and the gasket 23 is generally made of soft plastic such as butyl rubber or thermoplastic elastomer. .

  The electric double layer capacitor according to another embodiment of the present invention basically has the same structure as the proton polymer battery described above, and is included in the polarizable electrodes corresponding to the positive electrode 22 and the negative electrode 25 in FIG. Activated carbon is used as the electrode active material.

  By the way, in the above-described embodiment of the present invention, the upper lid (cap) and the lower lid (case) forming a metal coin case are caulked and sealed through an insulating packing, and then heated to obtain a vulcanized adhesive. When performing vulcanization, a step of completely vulcanizing the rubber covering the inner cell may be included. That is, the caulking and sealing is performed with the conductive rubber and non-conductive rubber covering the inner cell semi-cured or unvulcanized, and then the vulcanized adhesive is vulcanized and at the same time the outer cell is sheathed. Rubber vulcanization may be completed.

  Examples of the present invention will be described below. However, the present invention is not limited to this embodiment.

Example 1
The indole trimer (100% by weight), which is a positive electrode active material, is mixed with 20% by weight of vapor-grown carbon as a conductive material in a powder blender, and 10% by weight of PTFE (polytetrafluoroethylene) particles is used as a binder in the mixture. 60% by weight of PTFE dispersion was added so as to be% (weight ratio of PTFE particles with respect to the total weight after addition), mixed with a stirring deaerator, and then dried. 100% by weight of water was added to the obtained mixture and kneaded in a mortar. Thereafter, the kneaded product was rolled with a roll molding machine to obtain a sheet-like electrode having a thickness of 0.2 mm. The sheet-like positive electrode was punched out at φ2.0 mm to obtain a thin disc-like positive electrode.

  25% by weight of ketjen black EC600JD (manufactured by Lion Corporation) as a conductive material was added to polyphenylquinoxaline as a negative electrode active material with respect to the negative electrode active material and mixed with a powder blender. 100% by weight of m-cresol was added to the obtained mixed powder with respect to the total weight of the negative electrode active material and the conductive material, and kneaded with a kneader for 1 hour. M-Cresol was further added to the obtained kneaded material and mixed for 30 minutes with a homogenizer so that the viscosity of the mixed slurry became 1000 mPa · s to obtain a slurry.

  The obtained electrode slurry was applied onto polyethylene terephthalate (hereinafter referred to as PET), dried, and then the PET was peeled off to obtain a negative electrode sheet. The sheet-like negative electrode was punched out at φ2.0 mm to obtain a thin disc-shaped negative electrode.

  The separator is made of PTFE, the thickness is 50 μm (manufactured by Gore-Tex), the conductive rubber is carbon-added conductive unvulcanized butyl rubber, the thickness is 75 μm (manufactured by Fujikura Rubber Industrial Co., Ltd.), and the non-conductive rubber is unvulcanized butyl rubber. The thickness was 240 μm (manufactured by Fujikura Rubber Industrial Co., Ltd.), and the electrolyte used was 20% sulfuric acid added with 50% by weight of imidazole.

  A non-vulcanized butyl rubber of 90 mm × 90 mm was provided with 25 holes for electrode arrangement, each having a positive electrode φ of 2.3 mm and a negative electrode φ of 2.5 mm. This was arrange | positioned on the electroconductive unvulcanized butyl rubber of 90 mm x 90 mm which is a collector, and it crimped | bonded using the adhesiveness of rubber. A positive electrode and a negative electrode were inserted into the electrode placement holes, respectively, to form a positive electrode sheet and a negative electrode sheet, and a 2.5 mm separator was pressure-bonded to the positive electrode sheet. An electrolyte solution was poured into each electrode sheet and bonded in a vacuum.

The obtained positive and negative electrode integrated sheets were vulcanized in a range of an outer diameter of φ5.0 mm and an inner diameter of φ2.5 mm on the concentric circles of the holes into which the electrodes were inserted. The vulcanizing jig is configured to process the pressure surface into irregularities so that only the above-mentioned range can be vulcanized. The vulcanization method is such that only the jig on one side of the positive electrode and negative electrode integrated sheet is heated to 170 ° C. and pressurized for 30 seconds at a pressure of 10 kgf / cm ² , and then the sheet is cooled once. Inverted and heated in the same way from the side opposite to the first vulcanized surface. This vulcanization, cooling, and reversal of the heating surface were performed so that vulcanization was performed three times for each side of the positive electrode and negative electrode integrated sheet. In this state, the vulcanization is not complete, and is in a temporarily fixed state, and the peel strength of the vulcanized bonded portion is not sufficient.

  This sheet was punched out with a diameter of 3.2 mm on the concentric circle of the hole into which the electrode was inserted to form an inner cell. 25 internal cells are obtained from one sheet. PPS (polyphenylene sulfide) in which two internal cells are arranged in series, and a vulcanized adhesive (manufactured by Toyo Chemical Laboratory Co., Ltd.) is coated in a coin outer container composed of a stainless steel cap and a stainless steel case. ) Integrated through an insulating packing, and then sealed by caulking to obtain a coin-type proton polymer battery.

  The coating of the vulcanized adhesive (made by Toyo Chemical Laboratory Co., Ltd.) on the insulating packing made of PPS was made by dipping the primer (made by Toyo Chemical Laboratory Co., Ltd.) on the packing, and then dipping the vulcanized adhesive after drying. .

  The coin-type proton polymer battery was heated in a thermostatic bath at 160 ° C. for 15 minutes, and the gasket, current collector, and vulcanized adhesive of the internal cell were vulcanized. Between the gasket, between the gasket and the side of the inner cell, and the inside of the coin were completely vulcanized.

  Next, the defect occurrence rate when conducting a reflow test corresponding to lead-free reflow and a peak temperature of 260 ° C. was examined, and a 60 ° C. voltage energization reliability test in which sealing performance was greatly affected was conducted.

(Example 2)
In the process of Example 1, a coin-type proton polymer battery of Example 2 was obtained by using an internal cell produced without vulcanizing the positive and negative electrode integrated sheets temporarily.

(Example 3)
In the process of Example 2, a primer and a flow-adhesive adhesive were applied to the side surface of the internal cell instead of the PPS insulating packing to obtain a coin-type proton polymer battery of Example 3.

Example 4
The positive electrode, the negative electrode integrated sheet, and the vulcanization method were the same coin type electric double layer capacitor as in Example 3, and the electrode produced in the following manner was used.

Activated carbon having a specific surface area of 1500 m ² / g is used as an electrode active material, carbon black is mixed with activated carbon by 20% by weight in a powder blender as a conductive material, and PTFE particles are added to this mixture by 10% by weight (total amount after addition). 60 wt% PTFE dispersion was added so that the weight ratio of the PTFE particles to the weight) was mixed with a stirring deaerator, and then dried. 180% by weight of water was added to the obtained mixture and kneaded in a mortar. Thereafter, the kneaded product was rolled with a roll molding machine to obtain a sheet-like electrode having a thickness of 0.2 mm. The obtained sheet-like activated carbon electrode was punched out with a diameter of 2.3 mm to obtain a thin disk-like activated carbon electrode.

(Comparative Example 1)
Example 3 is the same as Example 3 except that no vulcanized adhesive is used.

(Comparative Example 2)
As a heat-resistant adhesive, a one-component heat-curable epoxy adhesive low-viscosity type was used. Other than that is the same as Example 3.

(Comparative Example 3)
Example 4 is the same as Example 4 except that no vulcanized adhesive is used.

  Table 1 shows the defect occurrence rate after performing the peak temperature 260 ° C. lead-free reflow test of Examples 1 to 4 and Comparative Examples 1 to 3 three times.

  As can be seen from Table 1, Examples 1 to 4 using the vulcanized adhesive of the present invention are compared with Comparative Examples 1 and 3 that do not use the conventional vulcanized adhesive and Comparative Example 2 that uses the epoxy adhesive. As a result, the failure rate decreased. This is because the internal pressure of the internal cell increased during reflow, and the vulcanized adhesive surface between the gasket and the current collector, which was the exterior of the internal cell, and the gasket-gasket adhesive layer peeled off, reducing the leakage of electrolyte inside. . The gasket and current collector made of butyl rubber on the side of the inner cell adhere to a stainless steel coin case and PPS insulating packing that are less deformed, making it difficult to deform and the force applied to the adhesive interface is reduced, making it difficult to peel off. Conceivable.

  In the case of Examples 1 to 4 using a vulcanized adhesive, the difference due to the adhesive is that the metal coin case, the PPS insulating packing and the primer are bonded by hydrogen bonding or anchor effect (physical adsorption), The primer and vulcanized adhesive are vulcanized and bonded. Between the vulcanized adhesive and the butyl rubber, the surface of the butyl rubber is polarized by hydrogen halide released from the vulcanized adhesive during vulcanization, and the cross-linking agent in the vulcanized adhesive is subjected to interfacial cross-linking and bonded. Good adhesion is obtained when the vulcanized adhesive fills a large difference in elastic modulus between metal, PPS insulating packing and butyl rubber, and makes the bonding interface compositionally continuous.

  On the other hand, the reason why the defect occurrence rate is not greatly improved in Comparative Example 2 using an epoxy adhesive is that the epoxy adhesive is firmly bonded to metal by hydrogen bonding. The butyl rubber and PPS insulating packing used for the inner cell are not chemically bonded to each other, resulting in weak adhesion with only an anchor effect. Therefore, during reflow, the inner cell and the coin case or packing are peeled off. This is thought to have occurred.

  There was no clear difference about Examples 1-4.

  In Table 2, after conducting the 260 ° C peak lead-free reflow test of Examples 1 to 4 and Comparative Examples 1 to 3 three times, the internal resistance when 2.5 [V] energization reliability test was conducted at 60 ° C ( 1 [kHz]) (the initial value is 100% and the value after the change is expressed in%).

  From the results in Table 2, it can be seen that the increase in internal resistance is suppressed in all of Examples 1 to 4 as compared with Comparative Examples 1 to 3. One possible cause of the increase in internal resistance is a decrease in the electrolyte due to the permeation of the electrolyte and water in the electrolyte to the outside of the cell, and an increase in the concentration of the electrolyte and additives. That is, it is considered that the higher the cell sealing property, the smaller the increase in internal resistance. From the results of Table 2, compared to Comparative Examples 1 to 3, the sealing properties of the cells are improved in all of Examples 1 to 4, and the coin case and packing in which the electrolyte solution permeated from the internal cell is vulcanized and bonded It is thought that the effect to suppress has come out.

  Although the difference between Example 1 and Examples 2 and 3 is not so large, the adhesive strength of the vulcanized adhesive becomes higher when the rubber to be bonded is unvulcanized. Resistance rise is small. Although there is no clear difference between Example 2 and Example 3, Example 3 is considered to have higher sealing performance than Example 2 because it is also vulcanized and bonded to the metal coin case part.

  Although the comparative example 2 using the epoxy adhesive showed improvement in characteristics as compared with the comparative example 1 not using the adhesive, the results were inferior to those of the example 3 using the vulcanized adhesive. This is considered to be because the difference in adhesive strength affected the sealing property as described above in Table 1.

1 is a cross-sectional view of a coin-type proton polymer battery according to the present invention. Sectional drawing of the internal cell which concerns on this invention. Sectional drawing of the coin-type battery of a prior art.

Explanation of symbols

11 Cap 12 Internal cell 13 Insulating packing 14 Case 15 Vulcanized adhesive 21 Current collector 22 Positive electrode 23 Gasket 24 Separator 25 Negative electrode 31 Sealant

Claims (6)

A pair of disk-shaped electrodes containing an electrode active material are opposed to each other with a separator interposed therebetween, a frame-shaped gasket made of non-conductive rubber is formed on a side surface of the electrode, and an exterior material in the direction of the upper and lower surfaces of the electrode The inner cell formed by sealing the conductive rubber and the non-conductive rubber by vulcanization adhesion after the injection of the electrolytic solution in a single layer or a laminated state, with a cap shape and a bottom In a coin-type electrochemical element in which the metal case is caulked and sealed via an annular resin packing so as to be accommodated in a metal case made of a cylindrical portion,
A coin-type electrochemical element, wherein a vulcanizing adhesive is applied to the resin packing, and the internal cell and the resin packing are vulcanized and bonded. A pair of disk-shaped electrodes containing an electrode active material are opposed to each other with a separator interposed therebetween, a frame-shaped gasket made of non-conductive rubber is formed on a side surface of the electrode, and an exterior material in the direction of the upper and lower surfaces of the electrode The inner cell formed by sealing the conductive rubber and the non-conductive rubber by vulcanization adhesion after the injection of the electrolytic solution in a single layer or a laminated state, with a cap shape and a bottom In a coin-type electrochemical device in which the metal case is caulked and sealed via an annular resin packing so as to be accommodated in a metal case made of a cylindrical portion,
A coin-type electrochemical element, wherein a vulcanizing adhesive is applied to a side surface of the internal cell, and the resin packing, the metal case, and the internal cell are vulcanized and bonded.   The coin-type electrochemical element according to claim 1, wherein the electrode includes a positive electrode or negative electrode active material, a conductive material, and a binder, and operates as a battery.   3. The coin-type electrochemical device according to claim 1, wherein activated carbon is used as the electrode active material and operates as an electric double layer capacitor. 5. The method for producing a coin-type electrochemical device according to claim 1, wherein the conductive rubber and the non-conductive rubber for covering the inner cell are in a semi-vulcanized state, and the vulcanization is performed. A step of caulking and sealing the metal case via the resin packing after application of the adhesive;
And a step of completely vulcanizing the conductive rubber and the non-conductive rubber by heating after caulking and sealing. It is a manufacturing method of the coin type electrochemical device according to any one of claims 1 to 4,
The step of caulking and sealing the metal case through the resin packing after application of the vulcanized adhesive, with the conductive rubber and non-conductive rubber covering the inner cell being unvulcanized,
And a step of vulcanizing the conductive rubber and the non-conductive rubber by heating after caulking and sealing, and a method for producing a coin-type electrochemical element.

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