JP4432405B2 - Method for manufacturing electrochemical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical device that is high in heat resistance, and to provide a method of manufacturing the device. <P>SOLUTION: The electrochemical device 100 comprises a pair of electrode layers 10 and 20 disposed in face to face with each other, a separator layer 40 disposed between the electrode layers 10 and 20, and electrochemical elements 61, 62, and 63 existing between the electrode layers 10 and 20 and having electrolytes. The device 100 also comprises a container 50 which hermetically seals the electrochemical elements 61, 62, and 63. The container 50 contains a C-stage epoxy resin layer 51. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to an electrochemical device and a method for manufacturing the same, and more particularly to an electrochemical device including an electrochemical capacitor including an electric double layer capacitor and a battery including a lithium ion secondary battery.

  Electrochemical devices such as electric double layer capacitors and batteries such as lithium ion secondary batteries are electrochemical devices that can be easily reduced in size and weight. It is expected as a power source for devices (small electronic devices), a backup power source, and an auxiliary power source for electric vehicles or hybrid vehicles.

  These electrochemical devices enclose the electrochemical element body, the electrochemical element body including a pair of opposing electrode layers, a separator layer disposed between the pair of electrode layers, and an electrolyte present between the pair of electrode layers. A container (exterior body) to be stopped.

And in Unexamined-Japanese-Patent No. 2001-35455, the electrochemical element body is the bag shape formed by the sheet | seat of the multilayer structure of the structure of PE or PP layer / aluminum layer / PET layer in an order from the side close | similar to an electrochemical element body. It is sealed in the container. As a sealing method, for example, an electrochemical element is contained in this bag-shaped container, and then the inside of the container is depressurized. About, it is heat sealed and sealed.
JP 2001-35455 A

  However, the electrochemical devices as described above have low heat resistance and are difficult to be surface-mounted. That is, when this electrochemical device is heated to 230 ° C. or higher in a reflow furnace or the like to surface-mount the electrochemical device as described above, the layer containing PP or PE in the container is softened and melted, and the exterior body It may be difficult to maintain the shape of the aluminum layer, and a short circuit may occur between the aluminum layer and the electrochemical element.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a high heat resistance electrochemical device.

The electrochemical device manufacturing method according to the present invention includes a pair of electrode layers facing each other, a separator layer disposed between the pair of electrode layers, and an electrochemical element having an electrolyte present between the pair of electrode layers. A housing step of wrapping with a sheet including the epoxy resin layer in a state, and a curing step of converting the epoxy resin layer of the sheet wrapping the electrochemical element into a C stage.

  According to this, the above-mentioned electrochemical device can be suitably produced. In particular, the epoxy resin layer in the B stage state is soft and easy to handle, so that workability is improved.

  Here, it is preferable that the gel fraction of the epoxy resin layer in the B stage state in the housing step is 20 to 80%. Here, if the gel fraction is lower than 20%, the sheet is too soft, the shape is not stable, and the workability tends to deteriorate. On the other hand, if the gel fraction is higher than 80%, the curing tends to progress too much, the sheet becomes too stiff, and workability tends to deteriorate again. In addition, curing may proceed excessively, and adhesion with the element body may not be obtained.

  Moreover, it is preferable to include the process of decompressing the inside of the area | region wrapped with the sheet | seat before a hardening process.

  According to this, a sheet | seat can be closely_contact | adhered with an electrochemical element | base_body by pressure reduction, and it becomes thinner and size reduction is attained.

  Moreover, the sheet | seat has comprised the bag shape and it is preferable to accommodate an electrochemical element | base_body in this bag in an accommodation process.

  This facilitates sealing of the electrochemical element body.

  Moreover, it is preferable that a hardening process includes at least one of the process of heating an epoxy resin layer, and the process of irradiating an ultraviolet ray to an epoxy resin layer, and can carry out C-stage easily by this.

  Further, it may further include a step of performing a water repellent treatment on the outer surface of the C-stage epoxy resin layer.

  As a result, the moisture permeability in the epoxy resin layer is further lowered, and thus the life can be extended.

High electrochemical device manufacturing method of the heat resistance is provided. Therefore, such an electrochemical device can be surface-mounted on a substrate or the like.

  Hereinafter, a preferred embodiment of the case where the electrochemical device of the present invention is applied to an electric double layer capacitor will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a partially broken perspective view showing an electric double layer capacitor 100 as an electrochemical device according to a first embodiment of the present invention. 2 is a YZ sectional view of FIG. 1, and FIG. 3 is an XZ plane sectional view of FIG.

  As shown in FIGS. 1 to 3, the electric double layer capacitor 100 according to this embodiment mainly includes a multilayer structure 85, a case (container) 50 that accommodates the multilayer structure 85 in a sealed state, and a multilayer structure. The lead conductor 12 and the lead conductor 22 are used to connect the body 85 and the outside of the case 50. The stacked structural body 85 includes a stacked body 80, and a current collecting terminal layer 15 and a current collecting terminal layer 18 that sandwich the stacked body 80 from both sides in the stacking direction (vertical direction) of the stacked body 80.

  The laminated body 80 includes a plate-like element body (electrochemical element body) 61, an element body (electrochemical element body) 62, and an element body (electrochemical element body) 63, and between the element body 61 and the element body 62. It has the plate-shaped collector layer 16 arrange | positioned, and the plate-shaped collector layer 17 arrange | positioned between the element body 62 and the element body 63.

  As shown in FIG. 2, the element body 61, the element body 62, and the element body 63 include a plate-like anode 10 (electrode layer) and a plate-like cathode 20 (electrode layer) facing each other, and the anode 10 and the cathode, respectively. 20 and a plate-like electrically insulating separator (separator layer) 40 disposed adjacent to the anode 20, and an electrolyte solution (not shown) including the anode 10, the cathode 20, and the electrolyte contained in the separator 40. ) And each.

  The anode 10 and the cathode 20 of each of the element body 61, the element body 62, and the element body 63 are electron-conductive porous bodies.

  The constituent materials of the anode 10 and the cathode 20 are not particularly limited, and are the same materials as those used as a porous layer constituting a polarizable electrode such as a carbon electrode used in a known electric double layer capacitor. Can be used. For example, it can be obtained by activation treatment of raw coal (for example, petroleum coke produced from a delayed coker that uses the bottom oil of a fluid catalytic cracking unit of petroleum heavy oil or the residual oil of a vacuum distillation unit as the raw material oil). A carbon material (for example, activated carbon) that is used as a main component of the constituent material can be used. Other conditions (types and contents of constituent materials other than carbon materials such as binder) are not particularly limited. For example, a conductive auxiliary agent (carbon black or the like) for imparting conductivity to the carbon powder and, for example, a binder (polytetrafluoroethylene, hereinafter referred to as PTFE) may be added.

  The separator 40 disposed between the anode 10 and the cathode 20 is not particularly limited as long as it is formed of an electrically insulating porous body, and a separator used in a known electric double layer capacitor may be used. it can. For example, as the electrically insulating porous body, at least one structure selected from the group consisting of a laminate of films made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of the above resins, or cellulose, polyester and polypropylene Examples thereof include a fiber nonwoven fabric made of a material.

  The electrolyte solution is contained in the anode 10, the cathode 20, and the pores of the separator 40. The electrolyte solution is not particularly limited, and an electrolyte solution (electrolyte aqueous solution, electrolyte solution using an organic solvent) used in a known electric double layer capacitor can be used. However, the electrolyte aqueous solution is preferably an electrolyte solution (non-aqueous electrolyte solution) that uses an organic solvent because the electrochemical breakdown voltage is low, which limits the capacitor withstand voltage.

  In the present embodiment, the electrolyte solution may be a gel electrolyte obtained by adding a gelling agent in addition to the liquid state. Further, instead of the electrolyte solution, a solid electrolyte (solid polymer electrolyte or an electrolyte made of an ion conductive inorganic material) may be contained.

  The current collector layer 16 and the current collector layer 17 and the current collector terminal layer 15 and the current collector terminal layer 18 are not particularly limited as long as they are good conductors that can sufficiently transfer charges. Known electric double layer capacitors The current collector used in the above can be used. For example, metal foils, such as aluminum, are mentioned.

  Here, the current collecting terminal layer 15 is formed between the inner surface of the sheet 51 </ b> C forming the case 50 of the electric double layer capacitor 100 and the element body 61, and the current collecting terminal layer 18 is formed between the inner surface of the sheet 51 </ b> C of the case 50. It is formed between the element body 63.

  As shown in FIGS. 1 to 3, in the electric double layer capacitor 100, the end face 85 a of the multilayer structure 85 including the multilayer body 80 is an electrically insulating sealing portion made of a resin cured by ultraviolet irradiation. 30 is sealed. The sealing portion 30 made of a resin cured by the irradiation of ultraviolet rays prevents leakage of the electrolyte solution from the element body 61, the element body 62, and the element body 63.

  Here, the resin cured by ultraviolet irradiation is an electrically insulating polymer resin formed by radical polymerization or cationic polymerization of a monomer or oligomer by ultraviolet irradiation.

  Here, specifically as resin hardened | cured by irradiation of an ultraviolet-ray, an epoxy resin, an epoxy (meth) acrylate resin, a (meth) acrylate resin, a urethane (meth) acrylate resin, a polyester (meth) acrylate resin, for example And the like. In particular, an epoxy resin, an epoxy (meth) acrylate resin, and a (meth) acrylate resin are preferable as the ultraviolet curable resin. Here, (meth) acrylate means an acrylate or a corresponding methacrylate.

  The resin cured by irradiation with ultraviolet rays is applied to the end face 85a with a resin raw material composition containing a monomer or oligomer photopolymerizable by ultraviolet irradiation, and then irradiated with ultraviolet rays to the resin raw material composition. It can be formed by polymerization and curing.

  Examples of the resin raw material composition for forming such a resin cured by irradiation with ultraviolet rays include conventionally known monomers and oligomers such as epoxy compounds, epoxy (meth) acrylates, (meth) Examples include monomers and oligomers such as acrylate, urethane (meth) acrylate, and ester (meth) acrylate.

  Moreover, it is preferable that this resin raw material composition contains a photoinitiator from a viewpoint of raising the intensity | strength of resin hardened | cured by ultraviolet irradiation. Moreover, the resin raw material composition may contain a plasticizer and a sensitizer as needed. In these cases, the resin cured by irradiation with ultraviolet rays contains other components such as a plasticizer, a sensitizer, a photopolymerization initiator, and a component obtained by decomposing the photopolymerization initiator by light.

  The photopolymerization initiator is not particularly limited as long as it is a conventionally known photopolymerization initiator, but in radical polymerization, for example, arylalkyl ketone, oxime ketone, acylphosphine oxide, S-phenyl thiobenzoate, Examples of the compound include titanocene, aromatic ketone, and thioxanthone. Examples of the cationic polymerization include aryldiazonium salts, aryliodonium salts, sulfonium salts, and sulfonylacetophenones.

  And as a method of apply | coating the resin raw material composition to the end surface 85a of the laminated structure 85, direct application methods, such as a nozzle method, a dipping method, an injection method, a transfer method, a brush coating etc., are mentioned, for example. it can.

  As shown in FIG. 1, the case (container) 50 is formed by folding a rectangular flexible sheet 51 </ b> C in half at a substantially central portion in the longitudinal direction. Direction). Of the end portion of the folded sheet 51C, the seal portions 50b on the three sides excluding the folded portion 50a are adhered by heat sealing or an adhesive, and the laminated structure 85 is sealed inside.

  And in the electrochemical device 100 which concerns on this embodiment, the sheet | seat 51C which comprises this case 50 is formed of the epoxy resin layer of a C stage state.

  Here, the A stage, the B stage, and the C stage of the epoxy resin will be described.

  A stage refers to a liquid uncured state of a so-called epoxy resin in which there is almost no crosslinking in the resin formed by ring opening of an epoxy group. The A-stage epoxy resin softens and melts when heated, and is completely dissolved in the solvent.

  The B stage refers to a so-called semi-cured state of an epoxy resin in which crosslinking is present in the resin at a certain concentration. The B-stage epoxy resin softens and melts when heated, but does not completely dissolve in the solvent but only partially dissolves.

  The C stage refers to a so-called completely cured state of an epoxy resin in which an epoxy resin is formed with a great number of crosslinks. The epoxy resin in the C stage state does not soften or melt even when heated, and is not dissolved in the solvent.

  The C-stage epoxy resin layer like the sheet 51C of the present embodiment can be formed by sufficiently curing an A-stage epoxy resin liquid or a B-stage epoxy resin sheet by ultraviolet irradiation or heating.

  Such an epoxy resin is not particularly limited as long as it contains a molecule having two or more epoxy groups in the molecule. For example, bisphenol (for example, bisphenol A) type epoxy resin, novolac type epoxy resin And alicyclic epoxy resins.

  As these epoxy resins, it is preferable to use an epoxy resin that is cured by ultraviolet irradiation or an epoxy resin that is cured by heating.

  The epoxy resin cured by heating preferably contains one or more curing agents. Examples of the curing agent include isocyanates, amines, acid anhydrides, polyamide resins, phenol resins, butylated urea formaldehyde resins, and the like. Can be mentioned.

  Moreover, it is preferable that the epoxy resin hardened | cured with an ultraviolet-ray contains one or more hardening | curing agents, for example, it is preferable to contain photoinitiators, such as a cationic polymerization initiator and a radical polymerization initiator.

  Examples of the cationic polymerization initiator and the radical polymerization initiator include those described above.

  In addition, the epoxy resin layer of the sheet 51C may include a reinforcing material such as glass fiber and a powder filler such as silica and alumina.

  As shown in FIG. 1, the lead conductor 12 has one end connected to the current collecting terminal layer 15 and the other end protruding outward from the seal portion 50 b of the case 50. On the other hand, one end of the lead conductor 22 is connected to the current collecting terminal layer 18, and the other end protrudes from the seal portion 50 b of the case 50 to the outside.

  As the lead conductor 12 and the lead conductor 22, for example, a conductive material such as aluminum or nickel can be used.

  Further, as shown in FIG. 1, the lead conductor 12 and the lead conductor 22 are each covered with an insulator 14 in the seal portion 50 b of the case 50 in order to improve the sealing performance. The seal portion 50b of the case 50 seals the lead conductor 12 and the lead conductor 22 so as to sandwich the insulators 14 and 14 therebetween. In addition, since there is no possibility of short-circuiting with the case 50, the operation is possible even without the insulator 14.

  Although the material of these insulators 14 is not specifically limited, For example, you may each be formed from the synthetic resin.

  According to the electric double layer capacitor 100 of this embodiment, the case 50 including the sheet 51C formed from the epoxy resin layer in the C stage state is provided. The C-stage epoxy resin layer sheet 51C hardly softens or melts even when heated to about 260 ° C. or higher. For this reason, an electric double layer capacitor will be excellent in heat resistance compared with the electric double layer capacitor containing conventional PE and PP. Therefore, such an electric double layer capacitor 100 can be surface-mounted on a substrate or the like in a reflow furnace or the like.

  Further, the sheet 51C including the epoxy resin layer in the C-stage state has higher adhesion to metal and superior heat resistance compared to other resin materials, so the thickness of the case 50 is smaller than that of the conventional case. And can be made thin. As a result, the electric double layer capacitor can be reduced in size and weight.

  In the present embodiment, the sealing portion 30 cured by ultraviolet rays seals the end face 85a of the laminated structure 85, that is, the end faces of the element bodies 61, 62, and 63. Since the sealing part 30 cured by the irradiation of the ultraviolet rays is cured without heating, the sealing part 30 itself is not heated when sealing each end face. Almost no heat is applied to the bodies 61, 62, and 63, and the electric double layer capacitor having a longer life and higher reliability is realized with little damage such as evaporation and alteration of the electrolyte solution.

  In addition, according to the electric double layer capacitor 100 of the present embodiment, the element bodies 61, 62, 63 have the laminated body 80 in which the conductive current collector layer 17 and the current collector layer 16 are laminated. The sealing portion 30 also seals the end face of the laminate 80.

  Therefore, even if the element body 61, the element body 62, and the element body 63 are not sealed individually one by one, the contact of the electrolyte between the element bodies 61, 62, between the element bodies 62, 63, that is, the short circuit can be sufficiently achieved. Can be prevented. Therefore, the electric double layer capacitor 100 having a series structure as in the present embodiment can be easily manufactured, and further reduction in thickness, size, and weight can be achieved.

  Moreover, according to the electric double layer capacitor 100 of the present embodiment, in addition to the multilayer body 80, the current collecting terminal layer 15 and the end face 85a of the current collecting terminal layer 18 sandwiching the laminated body 80 include a resin cured by irradiation with ultraviolet rays. Since it covers with the sealing part 30, the element bodies 61, 62 and 63 can be sealed with a high degree of sealing.

  Each element 61 to 63 of electric double layer capacitor 100 may have the configuration shown in FIG. That is, in each element body 61 to 63, the end face of each separator 40 may protrude outward from the end faces of the anode 10 and the cathode 20. In this case, it is possible to more reliably prevent a short circuit between the anode 10 and the cathode 20 in the same element body (for example, the element body 61). Here, it is preferable that the protruding length of the separator 40 is shorter than the combined length of the thickness of the anode 10 or the cathode 20 and half of the thickness of the separator 40, whereby the protruding portion of the separator 40 is bent. Moreover, it can prevent reliably that separator 40 contacts between adjacent element bodies. For example, it is possible to reliably prevent the separator 40 of the element body 61 and the separator 40 of the element body 62 from contacting each other at the tip portions. Even in this case, the sealing part 30 seals the end surfaces of the respective element bodies 61, 62, 63, the current collector layers 16, 17, and the current collector terminal layers 15, 18.

  The “anode” and “cathode” used in the description of the electric double layer capacitor 100 are determined based on the polarity of the electric double layer capacitor 100 at the time of discharge for convenience of description.

  Next, an example of a method for manufacturing the case 50 and the electric double layer capacitor 100 described above will be described.

  The manufacturing method of the element body 61 (a laminated body in which the anode 10, the separator 40, and the cathode 20 are sequentially laminated in this order) is not particularly limited, and a known thin film that is employed in the production of the known electric double layer capacitor 100. Manufacturing techniques can be used.

  When the electrode (porous body layer) to be the anode 10 and the cathode 20 is a carbon electrode (polarizable electrode), for example, a sheet-like electrode is produced using a carbon material such as activated carbon that has been activated by a known method. Can do. In this case, for example, after pulverizing the carbon material to about 5 to 100 μm and adjusting the particle size, for example, a conductive auxiliary agent (carbon black or the like) for imparting conductivity to the carbon powder, for example, a binder (polytetra Fluoroethylene (hereinafter referred to as PTFE) can be added and kneaded, and the kneaded product can be stretched and formed into a sheet shape.

  Here, as the conductive auxiliary agent, in addition to carbon black, powdered graphite or the like can be used, and as the binder, in addition to PTFE, PVDF, PE, PP, fluorine rubber, or the like is used. be able to.

  Next, the separator 40 is disposed in a state of contact between the anode 10 and the cathode 20 (non-adhered state), and the element bodies 61 to 63 are completed.

  Next, the element body 61, the element body 62 and the element body 63, the current collector layer 16, and the current collector layer 17 are arranged under the arrangement condition shown in FIG. Furthermore, the current collecting terminal layer 15 and the current collecting terminal layer 18 are arranged as shown in FIG. 5A to form a laminated structure 85, and the current collecting terminal layer 15 and the current collecting terminal layer 18 are respectively As shown in FIG. 1, the lead conductor 12 and the lead conductor 22 are electrically connected to each other.

  Note that a coating liquid (slurry) containing a constituent material for forming the electrodes to be the anode 10 and the cathode 20 may be prepared, and the laminated structure 85 described above may be formed using the coating liquid. For example, a coating solution is applied on the current collecting terminal layer 18 and dried to form the cathode 20. Next, the separator 40 is disposed on the cathode 20, and a coating solution is applied on the separator 40 and dried to form the anode 10, thereby forming the element body 63. In the same manner, the element body 62 and the element body 61 can be sequentially formed to form the laminated structure 85.

  Next, an electrolyte solution as described above is injected or impregnated into the laminated structure 85.

  Subsequently, the end surface 85a of the laminated structure 85 is sealed with a sealing portion 30 made of a resin cured by irradiation with ultraviolet rays. For example, as shown in FIG. 5B, a resin raw material composition 30a mainly composed of a monomer or an oligomer that can be polymerized by ultraviolet irradiation as described above is applied to the end face 85a, and then, FIG. As shown in FIG. 3, the applied resin raw material composition 30 a is irradiated with ultraviolet rays and cured to form the sealing portion 30.

  Next, an example of a method for manufacturing the case 50 will be described. First, as shown in FIG. 6A, a rectangular sheet 51B formed of an epoxy resin in a B stage state is prepared. Such a B-stage epoxy resin sheet 51B is formed by, for example, applying an A-stage epoxy resin on a plate-shaped substrate, and then heating or irradiating the epoxy resin to some extent. The sheet 51B of the epoxy resin in the B stage state is obtained as a flexible sheet having a predetermined softness.

  Here, the gel fraction G of the epoxy resin in the B-stage state is preferably 20 to 80%. According to this, the sheet 51B exhibits suitable flexibility to improve the accommodation workability of the laminated structure 85 and the sealing workability of the case, and the sheet 51B is sufficiently attached to the laminated structure 85 by the vacuum processing described later. In close contact.

  Here, if the gel fraction G is lower than 20%, the sheet 51B is too soft, the shape is not stable, and the workability tends to deteriorate. On the other hand, when the gel fraction G is higher than 80%, the curing progresses too much, the sheet 51B becomes too stiff, the workability is deteriorated again, and the adhesion to the laminated structure 85 also tends to be deteriorated.

  Here, the gel fraction G is the ratio of the weight W1 of the portion that has become insoluble in a solvent such as methyl ethyl ketone or ethanol due to crosslinking to the weight W0 of the entire epoxy resin, and G = W1 / W0.

  Alternatively, a composite sheet may be manufactured by bonding a metal foil on the B-stage epoxy resin sheet 51B via an adhesive or the like.

  Next, the sheet 51B is folded at the center dotted line and overlapped, and as shown in FIG. 6B, only the seal portions 50b and 50b on two sides are desired under a predetermined heating condition using, for example, a sealing machine. Heat seal only for the seal width. Thereby, a bag-like case 50f in which an opening 50c for introducing the laminated structure 85 is formed is obtained.

  Then, the laminated structure 85 in which the lead conductor 12 and the lead conductor 22 are electrically connected is inserted into the case 50f having the opening 50c. Subsequently, as shown in FIG. 6C, the air in the case 50f is exhausted from the opening 50c in the vacuum vessel 180 to make the inside of the case 50f in a vacuum state, and the lead conductor 12 and part of the lead conductor 22 are placed. In the state where each protrudes outward from the case 50f, the opening 50c of the case 50f is sealed using the sealing machine 82.

  Finally, the B-stage epoxy resin layer sheet 51B of the case 50f is C-staged to obtain a C-stage epoxy resin layer sheet 51C. Specifically, as shown in FIG. 6D, the sheet 51B of the case 50f may be heated or irradiated with light such as ultraviolet rays by a heater 84a or an ultraviolet lamp 84b. As a result, the sheet 51B is cured by further cross-linking to form a C stage, and the case 50 including the sheet 51C in the C stage state is formed, and the production of the electric double layer capacitor 100 is completed.

  Here, the heat treatment by the heater 84 is preferably performed at 50 to 200 ° C., more preferably 80 to 150 ° C.

  And the electric double layer capacitor produced by such a manufacturing method has the above-mentioned effects. In addition, since the pressure in the case 50f (in the region) wrapped with the sheet 51B is reduced before the C-stage curing process, the sheet 51B can be brought into close contact with the laminated structure 85, and the cured sheet 51C comes into close contact with the laminated structure 85. Therefore, the electric double layer capacitor 100 can be further reduced in thickness and size.

  Further, since the bag-like case 50f is used, the electrochemical element 61 and the laminated structure 85 can be easily sealed.

(Second embodiment)
Next, the electric double layer capacitor 200 according to the second embodiment will be described with reference to FIG. The electric double layer capacitor 200 according to the present embodiment is different from the electric double layer capacitor 100 of the first embodiment in that a metal layer 52 is further formed on the sheet 51C of the epoxy resin layer in the C stage state. That is, the case 50 includes a C-stage epoxy resin layer sheet 51 </ b> C and a metal layer 52. The metal layer 52 is disposed outside the sheet 51C. Examples of the material for the metal layer include aluminum, an aluminum alloy, titanium, and chromium.

  According to this, intrusion of moisture and air from the outside of the case 50 into the case 50 and leakage of the electrolyte component from the inside of the case 50 to the outside of the case 50 can be more effectively suppressed. Thereby, the lifetime of the electric double layer capacitor can be extended.

  In the present embodiment, the insulator 14 also exhibits an effect of preventing the lead conductor 12 and the lead conductor 22 from coming into contact with the metal layer 52 and short-circuiting.

(Third embodiment)
Next, an electric double layer capacitor 300 according to the third embodiment will be described with reference to FIG. The electric double layer capacitor 300 according to this embodiment is different from the electric double layer capacitor 100 of the first embodiment in that a water repellent film 53 is formed on a sheet 51C of an epoxy resin layer in a C stage state. is there.

  Such a water-repellent film 53 can be easily formed on the sheet 51C by using a fine particle of fluorine-based resin such as PTFE and a surface treatment agent such as fluorine-based varnish.

  According to this, since the moisture permeability in the case 50 is further lowered, the life of the electric double layer capacitor 300 can be extended.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, a mode in which three element bodies are stacked has been described, but the number of element bodies may be one, two, or three or more.

  Further, in the description of the above embodiment, the configuration suitable for the case where the present invention is applied to an electric double layer capacitor has been mainly described. However, the electrochemical device of the present invention is not limited to an electric double layer capacitor. For example, the present invention can be applied to electrochemical devices such as pseudo capacitors and redox capacitors.

  Furthermore, in the description of the above embodiment, a configuration suitable for the case where the present invention is applied to an electrochemical capacitor (particularly an electric double layer capacitor) has been described. However, the electrochemical device of the present invention is not limited to this. However, the present invention can also be applied to a secondary battery such as a lithium ion secondary battery. In this case, the porous layer serving as the first electrode (anode) contains an electrode active material that can be used for the anode of a secondary battery such as a lithium ion secondary battery. In addition, the porous layer serving as the second electrode (cathode) contains an electrode active material that can be used for the cathode of a secondary battery such as a lithium ion secondary battery.

  Hereinafter, the contents of the electrochemical device of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1
The electric double layer capacitor having the same configuration as the electric double layer capacitor 100 shown in FIGS.

(1) Production of electrode An anode (polarizable electrode) and a cathode (polarizable electrode) were produced by the following procedure. First, an activated carbon material subjected to activation treatment (specific surface area: 2000 m ² / g, manufactured by Kuraray Chemical Co., Ltd., trade name: “BP-20”) and a binder (fluoro rubber, manufactured by DuPont, trade name: “Viton- GF ”) and a conductive additive (acetylene black, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name:“ DENKABLACK ”), the mass ratio of which is carbon material: binder: conductive additive = 80: 10: 10 Was added to a solvent MIBK (methyl isobutyl ketone) and kneaded to prepare a coating liquid for electrode formation (hereinafter referred to as “coating liquid L1”).

  Next, four current collector layers (thickness: 50 μm) made of aluminum foil (corresponding to the current collector terminal layer 15, the current collector layer 16, the current collector layer 17, and the current collector terminal layer 18 in FIG. 2). Thing) Prepared. Next, with respect to two of them (corresponding to the current collecting terminal layer 15 and the current collecting terminal layer 18), the coating liquid L1 was uniformly applied on each one surface. For the remaining two (corresponding to the current collector layer 16 and the current collector layer 17), the coating liquid L1 was uniformly applied to both surfaces.

  Further, MIBK is then removed from the coating film by a drying treatment, and a laminate comprising the current collector layer and the dried coating film is pressed using a rolling roll, and is applied to one side of the current collector layer. An electron conductive porous layer (thickness: thickness: 37 μm) is formed on both sides of the current collector layer / electrode layer structure of the current collector layer / electrode layer formed with the electron conductive porous layer (thickness: 37 μm). Two three-layer laminates each having a structure of electrode layer / current collector layer / electrode layer formed with 37 μm) were prepared.

  Next, the two-layer laminate and the three-layer laminate were cut so as to have a rectangular shape (size: 8 mm × 8 mm). Furthermore, the water | moisture content adsorb | sucked to the surface of the electrode was removed by performing vacuum drying at the temperature of 150 to 175 degreeC with respect to these 2 layer laminated body and 3 layer laminated body for 12 hours or more.

(2) Production of Electric Double Layer Capacitor 100 Subsequently, 3 separators (8.1 mm × 8.1 mm, thickness: 0.05 mm, manufactured by Nippon Kogyo Paper Industries Co., Ltd., trade name: “TF4050”) made of a regenerated cellulose nonwoven fabric are used. Prepare one. Then, using these three separators and the two two-layer laminates and two three-layer laminates prepared in (1), these are divided into two-layer laminate / separator / 3-layer laminate / separator / 3-layer. The laminated structure 85 shown in FIG. 2 was produced by laminating in the order of laminate / separator / 2-layer laminate. Here, each two-layer laminate is disposed so that the electrodes in the two-layer laminate are in contact with the separator.

  Next, the surface of the current collector terminal layer (corresponding to the current collector terminal layer 15 and the current collector terminal layer 18 in FIG. 2) that is aluminum foil disposed on the upper and lower surfaces of the laminated structure 85 (formation of the porous body layer) Lead portions (width: 2 mm, length: 10 mm) made of aluminum foil were disposed on the outer edge portion of the surface that was not provided.

  Next, an electrolyte solution (1.8 mol / L propylene carbonate solution of triethylmethylammonium tetrafluoride) was injected into the laminated structure 85 under reduced pressure (2 to 10 mmHg). Next, an epoxy ultraviolet curable resin (trade name: “3113B”, manufactured by ThreeBond Co., Ltd.) was applied to the end face of the laminated structure 85 as a raw material resin composition that can be cured by ultraviolet rays. Thereafter, the end surface 85a of the laminated structure 85 coated with the ultraviolet curable resin was irradiated with ultraviolet rays to form a cured resin by irradiation of the ultraviolet rays, and the end surface 85a was sealed.

  Next, an epoxy resin sheet 51B in a B-stage state was formed in a bag shape having an opening 50c to produce a case 50f. The B-stage sheet 51B has a thickness of 50 μm and a gel fraction of 25%, and the epoxy resin is bisphenol A type and contains an acid anhydride-based curing agent.

  And the laminated structure 85 with a lead | read | reed was accommodated in such a case 50f, and the opening part 50c was heat-sealed, decompressing the inside of the case 50f.

  Finally, the case 50f formed from the B-stage sheet 51B is heat-treated in a furnace at 80 ° C. for 1 hour to cure the B-stage sheet 51B to form a C-stage sheet 51C, which has the case 50. An electric double layer capacitor was completed. Here, five similar electric double layer capacitors were prepared.

  And charging / discharging between 0-8.0V was performed with the constant current of 2 mA, and the internal resistance and the discharge capacity were measured.

  Specifically, a charge / discharge test apparatus (Hokuto Denko Co., Ltd., HJ-101SM6) was used for charge / discharge measurement. First, a current charge of 2 mA is performed, and the voltage rise is monitored as the electric charge is accumulated in the electric double layer capacitor. After the potential reaches 8 V, the voltage shifts to a constant voltage charge (relaxation charge). Was terminated when 1/10 of the charging current. Note that the total charging time (that is, charging time + relaxation charging time) at this time depends on the discharge capacity of the cell. The discharge was also a constant current discharge of 2 mA, and the final voltage was set to 0V. After this test, charging was performed at a current of 2 mA. After the potential reached 8 V, the charging was switched to constant voltage charging, and the charging was terminated when the current became 1/10 of the charging current. The discharge was also a constant current discharge of 2 mA, and the final voltage was set to 0V. Charging was started again and this was repeated 10 times.

The discharge capacity (electrostatic capacity of the electric double layer capacitor cell) was determined as follows. That is, the total discharge energy [W · s] is obtained from the discharge curve (discharge voltage vs. discharge time) as a time integral of discharge power (discharge voltage × current (= 2 mA), and discharge capacity [F] = total discharge energy [W The discharge capacity [F] of the evaluation cell was determined using the relational expression of s] / (discharge start voltage [V]) ² .

  Next, the internal resistance (impedance) of each electric double layer capacitor was determined by the following method. That is, a value at a frequency of 1 KHz measured using Solartron (trade name, manufactured by Toyo Technica Co., Ltd.) at a measurement environment temperature of 25 ° C. and a relative humidity of 60% is shown.

  Subsequently, these electric double layer capacitors were mounted on a predetermined substrate in a reflow furnace at 230 ° C., and the internal resistance and the discharge capacity were again measured in the same manner.

(Example 2)
The same as in Example 2 except that when the sheet 51B of the case 50f was cured, a pressure of 4.9 × 10 ⁵ Pa was applied from above the sheet 51B to the upper and lower surfaces of the laminated structure 85. .

(Comparative Example 1)
The case 50 was the same as the example 1 except that a case made of a composite sheet having a laminated structure of PP / aluminum / PET was used in this order from the laminated structure 85 side.

(Comparative Example 2)
Example 1 except that the case 50 was previously heat treated at 80 ° C. for 1 hour in a furnace and the C-staged case was housed and sealed in the case of the B stage. And so on.

  FIG. 9 shows the internal resistance and discharge capacity before reflow and the internal resistance and discharge capacity after reflow in these electric double layer capacitors, respectively.

  As apparent from the results shown in FIG. 8, the electric double layer capacitors of Examples 1 and 2 had an internal resistance of 11.0 to 11.5Ω and a discharge capacity of about 22 mF both before and after reflow. Thereby, it was understood that the electric double layer capacitor of Example 1 has high heat resistance and is suitable for reflow (surface mounting). Example 2 had almost the same result.

  On the other hand, the electric double layer capacitor of Comparative Example 1 was good with an internal resistance of 11.0 to 11.5Ω and a discharge capacity of about 22 mF before reflow. On the other hand, after reflow, none of them could be charged, and the result of internal resistance could not be obtained. This is probably because the PP layer was softened and melted in a 230 ° C. reflow furnace, and the aluminum layer and each element were short-circuited.

  In Comparative Example 2, since the case is C-staged, it is too hard to accommodate the laminated structure therein, and the case is cracked or the laminated structure 85 is sealed even by heating. The discharge capacity and internal resistance were not measured.

  From these, it was confirmed that according to the present invention, an electrochemical device having high heat resistance is provided.

FIG. 1 is a partially broken perspective view of the electric double layer capacitor according to the first embodiment. FIG. 2 is a cross-sectional view along the YZ plane of the electric double layer capacitor of FIG. FIG. 3 is a cross-sectional view along the XZ plane of the electric double layer capacitor of FIG. FIG. 4 is a schematic cross-sectional view showing a modification of the multilayer body 80 of the electric double layer capacitor of FIG. 5 (a), 5 (b) and 5 (c) are cross-sectional views sequentially showing a method for manufacturing the multilayer structure of the electric double layer capacitor of FIG. 6 (a) and 6 (b) are perspective views sequentially illustrating a method of manufacturing the case of the electric double layer capacitor of FIG. 1 following FIG. 5 (c), and FIGS. 6 (c) and 6 (d) are diagrams. FIG. 7 is a schematic diagram subsequent to FIG. FIG. 7 is a schematic cross-sectional view of the electric double layer capacitor according to the second embodiment. FIG. 8 is a schematic cross-sectional view of the electric double layer capacitor according to the third embodiment. FIG. 9 is a table showing characteristics of the electric double layer capacitors according to Examples 1 and 2 and Comparative Examples 1 and 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Anode (electrode layer), 20 ... Cathode (electrode layer), 15 ... Current collection terminal layer, 16, 17 ... Current collector layer, 18 ... Current collection terminal layer, 30 ... Sealing part, 40 ... Separator layer, 50 ... Case (container), 51C ... Sheet (C-stage epoxy resin layer), 51B ... Sheet (B-stage epoxy resin layer), 52 ... Metal layer, 61, 62, 63 ... Element (electrochemical element) Body), 80 ... laminate, 100, 200, 300 ... electric double layer capacitor (electrochemical device).

Claims (6)

An electrochemical element body having a pair of opposing electrode layers, a separator layer disposed between the pair of electrode layers, and an electrolyte present between the pair of electrode layers is wrapped with a sheet including an epoxy resin layer in a B-stage state. A containment process;
A curing step of C-stage the epoxy resin layer of the sheet enclosing the electrochemical element;
A method for producing an electrochemical device comprising: In the accommodating step, the gel fraction of the epoxy resin layer of the B-stage state, method for producing an electrochemical device according to claim 1 which is 20 to 80%. Wherein prior to the curing step includes the step of decompressing the wrapped area in the sheet, a manufacturing method of an electrochemical device according to claim 1 or 2. The method for manufacturing an electrochemical device according to any one of claims 1 to 3 , wherein the sheet has a bag shape, and the electrochemical element is stored in the bag in the storing step. The method for producing an electrochemical device according to any one of claims 1 to 4 , wherein the curing step includes at least one of a step of heating the epoxy resin layer and a step of irradiating the epoxy resin layer with ultraviolet rays. The method for producing an electrochemical device according to any one of claims 1 to 5 , further comprising a step of performing a water repellent treatment on an outer surface of the epoxy resin layer in the C-stage state.

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