JP2005045180A - Electrochemical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical element that can sufficiently prevent the electrolytes of elemental bodies from coming into contact with each other even when the elemental bodies are not hermetically sealed independently and, in addition, has an easily manufacturable constitution. <P>SOLUTION: The electrochemical element 1 is mainly constituted of two or more elemental bodies (61, 62, and 63) containing first and second electrodes 10 and 20 faced to each other and separators 40 adjacently disposed between the electrodes 10 and 20, an electrolytic solution contained in the elemental bodies (61, 62, and 63), and a case 50 which houses the elemental bodies (61, 62, and 62) in a hermetically sealing state. The elemental bodies (61, 62, and 63) are electrically connected in series; and the volume A of the electrolytic solution packed in the case 50 at 25°C in temperature and 1 atm in air pressure, the total volumes X and Y of vacant spaces in the first and second electrodes 10 and 20, and the total volume Z of vacant spaces in the separator 40, are adjusted to meet the condition expressed by the inequality of 0.95≤äA/(X+Y+Z)}≤1.0. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrochemical element, and more particularly to an electrochemical element including an electrochemical capacitor including an electric double layer capacitor and a battery including a lithium ion secondary battery.

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

  In the case where the above electrochemical element has a configuration in which two or more element bodies are electrically connected in series and stacked in one case, an electrolyte (for example, an electrolyte solution) contained in one element body is included. The structure which seals an element | base_element independently one by one is employ | adopted so that it may not contact the electrolyte (for example, electrolyte solution) contained in another adjacent element | base_body (for example, refer the following patent documents 1 and 2). ). However, each element body is electrically connected in series. In such a configuration, the withstand voltage of the electrochemical element is almost determined by the decomposition voltage of the electrolyte (for example, electrolyte solution). When the electrolyte contacts between the element bodies, the breakdown voltage of the electrolyte is higher than the decomposition voltage of the electrolyte. This is because the above-described voltage is applied to the electrolyte, and the decomposition reaction of the electrolyte proceeds.

  The “element body” as used herein refers to a first electrode and a second electrode facing each other, and a porous material formed from an insulating material disposed between the first electrode and the second electrode. The laminated body which consists of this separator is shown.

  More specifically, as shown in FIG. 10, an electrochemical element 800 having a configuration in which three element bodies (element body 601, element body 602, and element body 603) are electrically connected in series inside the case 500. For example, in the case of an electric double layer capacitor), a film 700 (for example, a film made of a synthetic resin) is disposed between each element body.

Note that the three element bodies 601 and 602 and the element body 603 are arranged so as to face each other, and the first electrode 100 and the second electrode 200, and the first electrode 100 and the second electrode. 200 and a separator 400 disposed between the two. Each of the first electrode 100, the second electrode 200, and the separator 400 includes a porous constituent material, and an electrolyte (for example, an electrolyte solution) is included inside.
JP 2000-58387 A JP 2001-35757 A

  However, since the conventional electrochemical elements including Patent Documents 1 and 2 have a configuration in which the element bodies are sealed individually one by one as described above, the manufacturing process is complicated and easy. Could not be manufactured.

  The present invention has been made in view of the above-described problems of the prior art, and can sufficiently prevent electrolyte contact between element bodies without using a structure in which element elements are sealed individually one by one, and An object of the present invention is to provide an electrochemical device having a structure that can be easily manufactured.

  As a result of intensive studies to achieve the above object, the present inventors have found that it is extremely effective to adopt an electrochemical element configuration that satisfies the following conditions, and have reached the present invention.

That is, the present invention includes a plate-like first electrode and a plate-like second electrode facing each other, and a plate-like separator disposed between the first electrode and the second electrode. Two or more elementary bodies having a configuration;
A plate-like current collector disposed between two or more element bodies;
An electrolyte solution;
A case containing two or more element bodies, a current collector and an electrolyte solution in a sealed state;
Have
The first electrode and the second electrode are composed of a porous layer composed of a porous body,
The separator is made of an insulating porous material,
At least part of the electrolyte solution is contained in the first electrode and the second electrode, and the separator,
Two or more element bodies are electrically connected in series,
The volume A of the electrolyte solution filled in the case at 25 ° C. and 1 atm, the total sum X of the void volumes in the first electrode of two or more element bodies, and the void in the second electrode of two or more element bodies The total volume Y and the total volume Z of the void volume in the separator of two or more element bodies satisfy the condition represented by the following formula (1),
An electrochemical device is provided.
0.95 ≦ {A / (X + Y + Z)} ≦ 1.05 (1)

  Here, in the present invention, the “element body” includes at least a first electrode and a second electrode facing each other, and an insulation is provided between the first electrode and the second electrode. The laminated body which has the structure by which the porous separator formed from the property material is arrange | positioned is shown. In addition, an electrolyte solution is contained inside the first electrode, the second electrode, and the separator. Further, the first electrode, the second electrode, and the separator may have a structure containing a solid electrolyte (a solid polymer electrolyte or an electrolyte made of an ion conductive inorganic material). Further, the first electrode and the second electrode are formed of a porous layer made of a porous body.

  Furthermore, in the present invention, an “electrochemical element” means an element having two or more element bodies and a structure in which the two or more element bodies are stacked in a state of being electrically connected in series. Indicates.

  More specifically, the “electrochemical element” preferably represents a secondary battery or an electrochemical capacitor. Preferably, the secondary battery includes a non-aqueous electrolyte secondary battery using a non-aqueous electrolyte such as a lithium ion secondary battery, a secondary battery using an aqueous electrolyte solution, and the like. Examples of the electrochemical capacitor include an electric double layer capacitor, a pseudo capacitance capacitor, and a redox capacitor.

  The inventors of the present invention have a configuration in which the element bodies are sealed individually one by one by adjusting the amount of the electrolyte solution contained in each element body so as to satisfy the condition represented by the formula (1). It has been found that the electrolyte contact between the element bodies can be sufficiently prevented even without this. Therefore, the electrochemical device of the present invention only needs to arrange a current collector between each element body, and can be easily manufactured.

  Here, in the present invention, if the electrolyte solution is filled in each element body in a range where the value of {A / (X + Y + Z)} exceeds 1.05, it becomes impossible to prevent the electrolyte contact between the element bodies. Further, when each element body is filled with an electrolyte solution in a range where the value of {A / (X + Y + Z)} is less than 0.95, the electrolyte solution does not sufficiently spread into the pores in the electrodes of each element body, A sufficiently large electric double layer interface cannot be formed, and the electric conductivity of the electrode is lowered. As a result, the internal resistance increases and sufficient charge / discharge characteristics cannot be obtained. From the viewpoint of obtaining the effect of the present invention more reliably, the value of {A / (X + Y + Z)} is preferably 0.98 to 1.0.

  Further, in the present invention, “the total sum X of void volumes in the first electrode of two or more element bodies” means the value of the total pore volume for each first electrode of each element body, This is the total sum of the first electrodes. However, when there are voids formed between the particles constituting the electrode constituent material or fine cracks in the electrode constituent material in the first electrode, the calculation is performed by adding the volume of the void and the volume of the crack. Is the value to be

  Furthermore, in the present invention, “the total sum Y of void volumes in the second electrode of two or more element bodies” means the value of the total pore volume for each second electrode of each element body, This is the total sum of the second electrodes. However, if there are voids formed between the particles constituting the electrode constituent material or fine cracks in the electrode constituent material in the second electrode, the volume of the void and the volume of the crack are also added to the calculation. Is the value to be

  Furthermore, in the present invention, “the total sum Z of void volumes in the separators of two or more element bodies” is a total sum of all the separators measured by measuring the value of the total pore volume for each separator of each element body. It is. However, when there are voids formed between the particles constituting the separator or fine cracks in the separator material in the separator, the value is calculated by adding the volume of the voids and cracks. .

  According to the present invention, there is provided an electrochemical element having a configuration that can sufficiently prevent electrolyte contact between element bodies and can be easily manufactured without having to separately seal the element bodies one by one. Can be provided.

  Hereinafter, a preferred embodiment of the case where the electrochemical element 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.

  FIG. 1 is a front view showing a preferred embodiment (electric double layer capacitor) of the electrochemical device of the present invention. FIG. 2 is a development view when the inside of the electrochemical device shown in FIG. 1 is viewed from the normal direction of the surface of the anode current collector 15. 3 is a schematic cross-sectional view of the electrochemical device shown in FIG. 1 cut along the line X1-X1 of FIG. FIG. 4 is a schematic cross-sectional view showing the main part when the electrochemical device shown in FIG. 1 is cut along the line X2-X2 in FIG. Further, FIG. 5 is a schematic cross-sectional view showing the main part when the electrochemical device shown in FIG. 1 is cut along the YY line of FIG. FIG. 6 is an enlarged view of a portion of the region R shown in FIG.

  As shown in FIGS. 1 to 5, the electric double layer capacitor 1 is mainly arranged between three element bodies (element body 61, element body 62 and element body 63), and between the element body 61 and the element body 62. Plate-shaped current collector 16, plate-shaped current collector 17 disposed between element body 62 and element body 63, and an electrolyte solution (not shown) contained in each element body , And a case 50 for housing them in a sealed state.

  A plate-like current collector 15 (hereinafter referred to as “anode current collector 15”) is disposed between the inner surface of the case 50 of the electric double layer capacitor 1 and the element body 61. Further, a plate-like current collector 18 (hereinafter referred to as “cathode current collector 18”) is disposed between the inner surface of the case 50 and the element body 63.

  Further, the anode current collector 15 of the electric double layer capacitor 1 is for an anode in which one end is electrically connected to the anode current collector 15 and the other end protrudes outside the case 50. The lead 12 and the cathode lead 22 having one end electrically connected to the cathode current collector 18 and the other end protruding outside the case 50 are provided.

  The three element bodies (element body 61, element body 62, and element body 63) include a plate-like anode 10 (first electrode) and a plate-like cathode 20 (second electrode) facing each other. , And a plate-like separator 40 disposed adjacently between the anode 10 and the cathode 20. The “anode” and “cathode” used in the description of the electric double layer capacitor 1 are determined based on the polarity of the electric double layer capacitor 1 during discharge for convenience of description.

  And the electric double layer capacitor 1 has the structure demonstrated below, in order to achieve the objective of this invention described previously.

  Details of each component of the present embodiment will be described below with reference to FIGS.

  First, the case 50 will be described. The case 50 has a first film 51 and a second film 52 that face each other. Here, as shown in FIG. 2, the first film 51 and the second film 52 in this embodiment are connected. That is, the case 50 in the present embodiment is formed by folding a rectangular film made of a single composite packaging film along a fold line X3-X3 shown in FIG. 2 and a pair of edges of the rectangular film facing each other ( The edge 51B of the first film 51 and the edge 52B of the second film 52 in the figure are overlapped to form an adhesive or heat seal.

  And the 1st film 51 and the 2nd film 52 show the part of this film which has the mutually opposing surface (F51 and F52) which is formed when one rectangular film is bent as mentioned above, respectively. . Here, in this specification, the surfaces of the two first films 51 and the second film 52 that are the materials of the case 50 are bonded to each other using heat seal (thermal fusion) or an adhesive. (Hereinafter, referred to as the “inner surface” of each film) or each of the first film 51 and the second film 52 after the first film 51 and the second film 52 are joined together The edge is referred to as a “seal”.

  Thereby, since it becomes unnecessary to provide the seal part for joining the 1st film 51 and the 2nd film 52 in the part of bending line X3-X3, the seal part in case 50 can be reduced more. As a result, the volume energy density based on the volume of the space in which the electric double layer capacitor 1 is to be installed can be further improved.

  Here, the “volume energy density” is originally defined by the ratio of the total output energy to the total volume including the container of the electric double layer capacitor (electrochemical element). On the other hand, “volume energy density based on the volume of the space to be installed” is an apparent requirement calculated based on the maximum vertical, maximum horizontal, and maximum thickness of an electric double layer capacitor (electrochemical element). The ratio of the total output energy of the electric double layer capacitor (electrochemical element) to the volume of. When an electric double layer capacitor (electrochemical element) is actually mounted on a small electronic device, the volume energy density based on the volume of the space to be installed should be improved in addition to the improvement of the original volume energy density described above. However, it is important from the viewpoint of effectively using a limited space in a small electronic device in a state where the dead space is sufficiently reduced.

  Here, the first film 51 and the second film 52 have flexibility.

  In the case of this embodiment, as shown in FIGS. 1 and 2, one end of each of the anode lead 12 connected to the anode current collector 15 and the cathode lead 22 connected to the cathode current collector 18. Is arranged so as to protrude outward from the seal portion where the edge portion 51B of the first film 51 and the edge portion 52B seal portion of the second film 52 are joined.

  Moreover, the film which comprises the 1st film 51 and the 2nd film 52 is a film which has flexibility as stated above. Since the film is lightweight and can be easily thinned, the electric double layer capacitor 1 itself can be formed into a thin film. Therefore, the original volume energy density can be easily improved, and the volume energy density based on the volume of the space in which the electric double layer capacitor 1 is to be installed can be easily improved.

This film is not particularly limited as long as it is a flexible film. However, while ensuring sufficient mechanical strength and light weight of the case, moisture and air can enter from the outside of the case to the inside of the case and from the inside of the case to the outside of the case. From the standpoint of effectively preventing the electrolyte component from escaping, the “composite packaging” has at least an innermost layer made of synthetic resin in contact with the electrolyte solution and a metal layer disposed above the innermost layer. A “film” is preferred.
Examples of the composite packaging film that can be used as the first film 51 and the second film 52 include a composite packaging film having a configuration shown in FIGS. 7 and 8.
The composite packaging film 53 shown in FIG. 7 has a metal innermost layer 50a that contacts the electrolyte solution on its inner surface F50a and a metal disposed on the other surface (outer surface) of the innermost layer 50a. With layer 50c. Further, the composite packaging film 54 shown in FIG. 8 has a configuration in which an outermost layer 50b made of synthetic resin is further arranged on the outer surface of the metal layer 50c of the composite packaging film 53 shown in FIG.

  The composite packaging film that can be used as the first film 51 and the second film 52 includes two or more layers including one or more synthetic resin layers including the innermost layer described above and a metal layer such as a metal foil. Although it will not specifically limit if it is the composite packaging material which has a layer, From the viewpoint of acquiring the same effect as the above more reliably, like the composite packaging film 54 shown in FIG. 7, the innermost layer and the innermost layer 3 layers having an outermost layer made of synthetic resin disposed on the outer surface side of the case 50 farthest from the surface and at least one metal layer disposed between the innermost layer and the outermost layer More preferably, it is composed of the above layers.

  The innermost layer is a layer having flexibility, and the constituent material can express the above-mentioned flexibility, and chemical stability (chemical reaction, dissolution, It is not particularly limited as long as it is a synthetic resin having a characteristic that does not cause swelling) and chemical stability to oxygen and water (water in the air), but oxygen, water (water in the air) and electrolyte Materials having low permeability to the components of the solution are preferred. Examples thereof include thermoplastic resins such as polyethylene, polypropylene, polyethylene acid modified product, polypropylene acid modified product, polyethylene ionomer, and polypropylene ionomer.

  Further, when a synthetic resin layer such as the outermost layer 50b is further provided in addition to the innermost layer 50a as in the composite packaging film 54 shown in FIG. 7 described above, this synthetic resin layer Alternatively, the same constituent material as the innermost layer may be used. Further, as the synthetic resin layer, for example, a layer made of engineering plastic such as polyethylene terephthalate (PET) or polyamide (nylon) may be used.

  Moreover, the sealing method of all the sealing parts in the case 50 is not particularly limited, but the heat sealing method is preferable from the viewpoint of productivity.

  The metal layer is preferably a layer formed of a metal material having corrosion resistance against oxygen, water (water in the air) and an electrolyte solution. For example, a metal foil made of aluminum, aluminum alloy, titanium, chromium, or the like may be used.

  Next, the element body 61, the element body 62, and the element body 63 will be described with reference to FIGS.

  The anodes 10 of the element body 61, the element body 62, and the element body 63 are each composed of a porous layer made of an electron conductive porous body. The cathode 20 includes a porous layer 28 made of an electron conductive porous body.

  The constituent materials of the anode 10 and the cathode 20 are not particularly limited, and are the same materials as those used for the 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.

  However, from the viewpoint of sufficiently ensuring the contact interface with the electrolyte solution, the total sum X of the void volumes in each anode 10 is preferably 60 to 80 μL when the porous body layer volume is 100 mL, and is 65 to 75 μL. More preferably. Further, the total sum Y of the void volumes in each cathode 20 is preferably 60 to 80 μL, and more preferably 65 to 75 μL when the porous body layer volume is 100 mL. The total void volume X and the total void volume Y can be determined by the ethanol impregnation method.

  The separator 40 disposed between the anode 10 and the cathode 20 is not particularly limited as long as it is formed of an insulating porous body, and a separator used in a known electric double layer capacitor can be used. . For example, as the insulating porous body, at least one constituent material 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 The fiber nonwoven fabric which consists of is mentioned.

  However, from the viewpoint of sufficiently ensuring the contact interface with the electrolyte solution, the total sum Z of the void volumes of each separator 40 is preferably 50 to 75 μL, and preferably 60 to 70 μL when the porous body layer volume is 100 μL. More preferred. The method for obtaining the total void volume Z is not particularly limited, and can be obtained by a known method.

  Next, the current collector 16 and the current collector 17, the anode current collector 15 and the cathode current collector 18 are good conductors that can sufficiently transfer charges to the porous body layer 18 and the porous body layer 28. The current collector is not particularly limited, and a current collector used in a known electric double layer capacitor can be used. For example, metal foils, such as aluminum, are mentioned.

  The cathode current collector 18 is electrically connected to one end of a cathode lead 22 made of aluminum, for example, and the other end of the cathode lead 22 extends to the outside of the case 50. On the other hand, the anode current collector 15 is also electrically connected to one end of an anode lead conductor 12 made of, for example, copper or nickel, and the other end of the anode lead conductor 12 extends to the outside of the enclosing bag 14.

  The electrolyte solution is contained inside the anode 10 and the cathode 20 and the separator 40. The amount of the electrolyte solution filled in the internal space of the case 50 is adjusted so as to satisfy the following conditions in order to obtain the effects of the present invention described above.

That is, the volume A [μL] at 25 ° C. and 1 atm of the electrolyte solution filled in the case 50, the total X [μL] of the void volume in each anode 10 of each element 61 to 63, and each element 61 The total sum Y [μL] of the void volume in each cathode 20 to 63 and the total Z [μL] of the void volume in each separator 40 of each element 61 to 63 are represented by the following formula (1). The condition is met.
0.95 ≦ {A / (X + Y + Z)} ≦ 1.05 (1)
Thereby, even if it is not set as the structure which seals each element | base_body 61-63 independently one by one, the contact of the electrolyte between element | base_elements can fully be prevented. And the electric double layer capacitor 1 which has the structure which can be manufactured easily can be comprised.

  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.

  Furthermore, the type of the electrolyte solution is not particularly limited, but is generally selected in consideration of the solubility of solute, the degree of dissociation, and the viscosity of the solution. A solution is desirable. For example, as a typical example, a quaternary ammonium salt such as tetraethylammonium tetrafluoroborate dissolved in an organic solvent such as propylene carbonate, diethylene carbonate, or acetonitrile is used. In this case, it is necessary to strictly manage the moisture content.

  Here, in the present invention, the “electrolyte solution” may be a gel electrolyte obtained by adding a gelling agent in addition to the liquid state.

  Moreover, from the viewpoint of obtaining the effect of the present invention more reliably, each element body 61 to 63 of the electric double layer capacitor 1 has a configuration shown in FIG. FIG. 6 is an enlarged view of a region R shown in FIG.

That is, the anode 10 (first electrode) and the cathode 20 (second electrode) have the same shape and size, and the area S1 of the main surface F1 of the anode 10 and the main surface F2 of the cathode 20 are the same. The area S2 and the area S3 of the main surface F3 of the separator 40 satisfy the condition represented by the following formula (2), and in each element body 61 to 63, from the edge of the main surface F1 or the main surface F2 The maximum width Ws of the edge portion of the main surface F3 projecting to the outside, the thickness T1 of the anode 10 and the cathode 20, and the thickness T2 of the current collector 16 (or current collector 17) are expressed by the following formula (3). The condition represented by is satisfied.
S3> S1 = S2 (2)
Ws ≧ (T1 + T2 / 2) (3)
Note that “the main surface F1 of the anode 10 (the main surface F1 of the first electrode)” indicates a surface of the surface of the anode 10 that contacts the separator 40. Further, “the main surface F2 of the cathode 20 (the main surface F2 of the second electrode)” indicates a surface of the surface of the cathode 20 that contacts the separator 40. Furthermore, “the main surface F3 of the separator 40” refers to the surface of the separator 40 that contacts the main surface F1 of the anode 10 and the surface that contacts the main surface F2 of the cathode 20.

  By making the separator 40 larger than the anode 10 and the cathode 20 within a range that satisfies the conditions of the expressions (2) and (3) at the same time, the anode 10 and the cathode 20 in the same element body (for example, the element body 61). A short circuit can be prevented more reliably. Moreover, even if the protrusion part of the separator 40 bends in this case, it can prevent reliably that separators 40 contact 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.

  In addition, as shown in FIGS. 4 and 5, when a gap is formed between the laminated body including the element bodies 61 to 63 and the inner surface of the case 50, a shape suitable for the shape and size of the gap and A spacer 30 having a size (for example, a spacer made of a synthetic resin such as an adhesive) is disposed.

  Further, as shown in FIGS. 1 and 2, the anode lead 12 is in contact with the sealing portion of the encapsulating bag composed of the edge 51 </ b> B of the first film 51 and the edge 52 </ b> B of the second film 52. Is coated with an insulator 14 for preventing contact between the anode lead 12 and the metal layer in the composite packaging film constituting each film. Furthermore, the cathode lead 22 and each film are formed in the portion of the cathode lead 22 that comes into contact with the sealing portion of the encapsulating bag composed of the edge 51B of the first film 51 and the edge 52B of the second film 52. An insulator 24 for preventing contact with the metal layer in the composite packaging film is coated.

  The configurations of the insulator 14 and the insulator 24 are not particularly limited. For example, the insulator 14 and the insulator 24 may be made of a synthetic resin. It should be noted that the insulator 14 and the insulator 24 may not be disposed as long as the metal layer in the composite packaging film can be sufficiently prevented from contacting the anode lead 12 and the cathode lead 22 respectively.

  Further, from the viewpoint of enabling installation in a limited installation space within a portable small electronic device, the electric double layer capacitor 1 has a thickness (total thickness of the electric double layer capacitor 1) of 0.2. It is preferable that it is -2.0mm, and it is more preferable that it is 0.2-1.0mm.

  Furthermore, from the viewpoint of enabling installation in a limited installation space within a portable small electronic device, it is preferable that each thickness of the element bodies 61 to 63 is 0.1 to 0.4 mm. More preferably, it is 0.1 to 0.3 mm.

  Next, an example of a method for manufacturing the case 50 and the electric double layer capacitor 1 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 is a known thin film that is employed in the production of the known electric double layer capacitor 1. 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 anode lead conductor 12 and the cathode lead 22 are electrically connected to the anode 10 and the cathode 20, respectively. The separator 40 is disposed in a contacted state (non-adhered state) between the anode 10 and the cathode 20 to complete the element bodies 61 to 63.

  Next, the element body 61, the element body 62 and the element body 63, the anode current collector 15, the current collector 16, the current collector 17, and the cathode current collector 18 are arranged under the arrangement conditions shown in FIG. And these laminated bodies (henceforth "the laminated body A") are formed.

  Moreover, the above-mentioned laminated body A may be formed using a coating liquid (slurry) containing a constituent material for forming electrodes to be the anode 10 and the cathode 20. For example, a coating solution is applied on the cathode current collector 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. Thereafter, the element body 62 and the element body 61 are sequentially formed in the same manner to form the laminate A.

  Next, an example of a method for manufacturing the case 50 will be described. First, when the first film and the second film are composed of the composite packaging film described above, a dry lamination method, a wet lamination method, a hot melt lamination method, and an extrusion lamination method are used. It is produced using a known production method such as

  For example, a film that is a synthetic resin layer that constitutes the composite packaging film, and a metal foil made of aluminum or the like are prepared. The metal foil can be prepared, for example, by rolling a metal material.

  Next, a composite packaging film (multilayer film) is preferably obtained by laminating a metal foil via an adhesive on a film that becomes a layer made of a synthetic resin so as to have a configuration of a plurality of layers described above. Is made. Then, the composite packaging film is cut into a predetermined size to prepare one rectangular film.

  Next, as described above with reference to FIG. 2, one film is folded, and the seal portion 51B (edge portion 51B) of the first film 51 and the seal portion 52B (edge portion) of the second film. 52B) is heat-sealed by a desired seal width under a predetermined heating condition using, for example, a sealing machine. At this time, in order to secure an opening for introducing the laminated body A into the case 50, a part where heat sealing is not performed is provided. As a result, the case 50 having an opening is obtained.

  Then, the laminate A in which the anode lead conductor 12 and the cathode lead 22 are electrically connected is inserted into the case 50 having an opening. Then, an electrolyte solution is injected. Subsequently, with the anode lead 12 and the cathode lead 22 partially inserted into the case 50, the opening of the case 50 is sealed using a sealing machine. In this way, the manufacture of the case 50 and the electric double layer capacitor 1 is completed.

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

  Further, in the description of the above embodiment, the three stacked element bodies have been described. However, the number of element bodies in the electrochemical element of the present invention is not limited to the above embodiment. The number may be two or more.

  Furthermore, in the description of the above-described embodiment, a configuration suitable for the case where the present invention is applied to an electrochemical capacitor (especially an electric double layer capacitor) has been described. However, the electrochemical device of the present invention is 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.

  In the present invention, the case may be a can-shaped exterior body (metal case) formed from a metal member in addition to the above-described composite packaging film. Thereby, it can apply to uses, such as a case where mechanical strength higher than a composite packaging film is requested | required with respect to a case.

  As an embodiment of an electrochemical element having a can-shaped exterior body formed from such a metal member, there is an electrochemical element 1A shown in FIG. FIG. 9 is a schematic cross-sectional view showing another embodiment of the electrochemical device of the present invention.

  FIG. 9 shows a coin-type electrochemical element 1A (electric double layer capacitor) as an electrochemical device according to an embodiment of the present invention.

  The electrochemical device 1A mainly includes three element bodies (element body 61, element body 62, and element body 63), and a plate-like current collector 16 disposed between the element body 61 and the element body 62. The plate-like current collector 17 disposed between the element body 62 and the element body 63, an electrolyte solution (not shown) contained in each element body, and a case for containing these in a sealed state 50A (metal can-like exterior body). A plate-like anode current collector 15 is disposed between the inner surface of the case 50 </ b> A of the electric double layer capacitor 1 and the element body 61. Further, a plate-like cathode current collector 18 is disposed between the inner surface of the case 50 </ b> A and the element body 63.

  The electrochemical element 1A shown in FIG. 9 has the same configuration as that of the electric double layer capacitor 1 described with reference to FIGS. 1 to 8 except for the case 50A (metal can-like exterior body). .

  The case 50A (metal can-like exterior body) is a container that seals three element bodies (element body 61, element body 62, and element body 63) from above and below, and an upper lid (one of metal members). 53 and a lower lid (the other metal member) 54, and a gasket 70 that electrically insulates the upper lid 53 and the lower lid 54.

  The upper lid 53 and the lower lid 54 are a laminated body (hereinafter referred to as “laminated body A1”) including three element bodies (element body 61, element body 62, and element body 63), the anode current collector 15 and the cathode current collector 18. ) Is sandwiched from above and below to surround the laminate A1.

  The lower lid 54 is formed from a metal foil such as aluminum. The lower lid 54 has a cylindrical cylindrical portion 54a whose lower end is closed and whose upper end is opened, and a flange portion 54b (end portion) formed in an annular shape so as to protrude outward from the upper end portion of the cylindrical portion 54a. And have. The bottom of the cylindrical portion 54 a of the lower lid 54 is in contact with the cathode current collector 18.

  The upper lid 53 is made of a metal foil such as aluminum, and is provided along a plate-like central portion 53a that covers the opening of the lower lid 54 and is in contact with the anode current collector 15, and a peripheral edge of the central portion 53a. It has a caulking portion (end portion) 53b that clamps the flange portion 54b of the lower lid from above and below.

  Specifically, the caulking portion 53b of the upper lid 53 extends outward along the upper surface of the flange portion 54b of the lower lid 54 while interposing an insulating gasket 70 between the flange portion 54b of the lower lid 54 and the flange portion 54b of the lower lid 54. It is bent downward at the outer end of the portion 54b, and further extends inward along the lower surface of the flange portion 54b. The caulking portion 53b is caulked to the flange portion 54b so as to sandwich the flange portion 54b from above and below, with the gasket 70 interposed between the crimp portion 53b and the flange portion 54b. In this way, the laminate A1 is sealed inside the exterior body formed by the upper lid 53 and the lower lid 54.

  The central portion 53a of the upper lid 53 is electrically connected to the anode 10 of the multilayer body A1 via the anode current collector 15, so that the upper lid 53 functions as the anode of the electrochemical element 1A. Further, the bottom portion of the cylindrical portion 54a of the lower lid 54 is electrically connected to the cathode 20 of the multilayer body A1 via the cathode current collector 18, so that the lower lid 54 functions as a cathode of the electrochemical element 1A. To do. The gasket 70 electrically insulates between the upper lid 53 and the lower lid 54.

  In particular, in this embodiment, the caulking portion 53 b of the upper lid 53 and the flange portion 54 b of the lower lid 54 are bonded by the gasket 70.

  As such a gasket 70, a resin that adheres to a metal can be used. For example, resins such as acid-modified polypropylene and acid-modified polyethylene are preferable. When such a resin that adheres to a metal by heating is used as the gasket 70, the caulking portion 53b of the upper lid 53 is caulked against the flange portion 54b of the lower lid 54 with the gasket 70 interposed therebetween. By heating the gasket 70 from the outside, the upper lid 53 and the lower lid 54 can be easily bonded to each other by the gasket 70. Further, as the gasket 70, an adhesive such as an epoxy resin may be used, and caulking and bonding may be performed simultaneously.

  In the above-described embodiment, the gasket 70 that exhibits adhesiveness to the metal by heating is used, and heat treatment is performed after crimping. For example, electrical insulation that exhibits adhesiveness on the upper and lower surfaces of the flange portion 54b is used. After applying a functional resin as a gasket, the upper lid may be placed and caulked.

  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)
An electric double layer capacitor having the same configuration as that of the electric double layer capacitor 1 shown in FIGS. 1 to 8 was produced by the following procedure.

(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 {fluororubber, 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 auxiliary agent = 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 collectors (thickness: 50 μm) made of aluminum foil (corresponding to the anode current collector 15, the current collector 16, the current collector 17, and the cathode current collector 18 in FIG. 4) are prepared. did. Next, for two of them (corresponding to the anode current collector 15 and the cathode current collector 18), the coating liquid L1 was uniformly applied on one surface of each. For the remaining two (corresponding to the current collector 16 and the current collector 17), the coating liquid L1 was uniformly applied to both surfaces.

  Then, MIBK is removed from the coating film by a drying treatment, and a laminate comprising the current collector and the dried coating film is pressed using a rolling roll, and electron conduction is performed on one surface of the current collector. Electrode having a porous layer (thickness: 37 μm) formed thereon and an electrode having an electron conductive porous layer (thickness: 37 μm) formed on both sides of the current collector (Hereinafter, referred to as “electrode E2”), two each were prepared.

Next, the electrode E1 and the electrode E2 were cut so as to have a rectangular shape (size: 8 mm × 8 mm). Furthermore, by performing vacuum drying at a temperature of 150 ° C. to 175 ° C. for 12 hours or more, moisture adsorbed on the surface of the electron conductive porous body layer is removed, and the electrode and the current collector are integrated (electrode E1 The two manufactured from the above are referred to as “electrode E10”, and the two manufactured from the electrode E2 are referred to as “electrode E20”).
Then, as shown in FIG. 4, three element bodies and anodes and cathodes were produced.

(2) Production of Electric Double Layer Capacitor 1 Separators (8.1 mm × 8.1 mm, thickness: 0.05 mm, Nippon Advanced Co., Ltd.) comprising two produced electrodes E10, two electrodes E20, and three regenerated cellulose nonwoven fabrics The product “Laminate A” shown in FIG. 4 was produced by laminating them using a paper industry, product name: “TF4050”).

  Next, the surfaces of the current collectors (corresponding to the anode current collector 15 and the cathode current collector 18 in FIG. 4) disposed on both ends of the laminate A (on the side where the porous body layer is not formed). Lead portions (width 2 mm, length 10 mm) made of aluminum foil were disposed on the outer edge of the surface.

  Next, a sealant material was thermocompression bonded to the tab portion. Next, the laminated body (element body) was put into a case formed of a composite packaging film having flexibility, and the tab portions were heat sealed. As a flexible composite packaging film, the innermost layer made of synthetic resin (a layer made of modified polypropylene) in contact with the electrolyte solution, a metal layer made of aluminum foil, and a layer made of polyamide are sequentially laminated in this order. A laminate was used. And two sheets of this composite packaging film were piled up, and the edge part was heat-sealed and produced.

  After the electrolyte solution (1.8 mol / L propylene carbonate solution of triethylmethylammonium tetrafluoride) was injected into the case, vacuum sealing was completed to complete the production of the electric double layer capacitor. At this time, the volume A [μL] of the electrolyte solution injected into the case was adjusted so that {A / (X + Y + Z)} = 1.00.

In each body was ^{S1 = 64.0mm 2, S2 = 64.0mm} 2, S3 = 65.61mm 2. Ws = 50 μm, T1 = 37 μm, and T2 = 50 μm.

(Example 2) and (Example 3)
The electric double layer capacitor of Example 1 except that the volume A [μL] of the electrolyte solution injected into the case is adjusted so that the value of {A / (X + Y + Z)} becomes the value shown in Table 1. An electric double layer capacitor was produced by the same procedure and conditions as in Example 1.

(Comparative Example 1) and (Comparative Example 2)
The electric double layer capacitor of Example 1 except that the volume A [μL] of the electrolyte solution injected into the case is adjusted so that the value of {A / (X + Y + Z)} becomes the value shown in Table 1. An electric double layer capacitor was produced by the same procedure and conditions as in Example 1.

[Characteristic evaluation test of electric double layer capacitor]
The following various characteristics were measured for each of the electric double layer capacitors of Examples 1 to 3 and Comparative Examples 1 and 2.

  For the measurement of charge / discharge, a charge / discharge test apparatus (HJ-101SM6, manufactured by Hokuto Denko Co., Ltd.) was used. First, charge at a low current of 0.5C and monitor the voltage rise as the electric charge accumulates in the electric double layer capacitor. After the potential reaches 2.5V, constant voltage charge (relaxation charge) The charging was terminated when the current became 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 capacitance of the cell. The discharge was also a constant current discharge of 0.5 C, and the final voltage was set to 0V. After this test, the battery was charged with a current of 1 C. After the potential reached 2.5 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 1 C, and the final voltage was set to 0V. Charging was started again and this was repeated 10 times.

The capacitor capacity (electrostatic capacity of the electric double layer capacitor cell) was determined as follows. That is, the total discharge energy [W · s] is obtained as a time integral of discharge energy (discharge voltage × current (= 10 mA)) from the discharge curve (discharge voltage−discharge time), and capacitor capacity [F] = 2 × total discharge energy [ The capacitor capacity [F] of the evaluation cell was determined using the relational expression of W · 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.

  Table 1 shows the capacitance of each electric double layer capacitor of Examples 1 to 3 and Comparative Examples 1 and 2 (the capacitance of the electric double layer capacitor cell) and the internal resistance (impedance). Show.

  The electrochemical element can be used for an electrochemical capacitor including an electric double layer capacitor and a battery including a lithium ion secondary battery. For example, a backup of a power source of a portable device (small electronic device) or the like. It can be used as a power source for vehicles and an auxiliary power source for hybrid vehicles.

It is a front view which shows suitable one Embodiment of the electrochemical element of this invention. FIG. 2 is a development view when the inside of the electrochemical device shown in FIG. 1 is viewed from the normal direction of the surface of an anode current collector 15. It is a schematic cross section at the time of cut | disconnecting the electrochemical element shown in FIG. 1 along the X1-X1 line | wire of FIG. It is a schematic cross section which shows the principal part at the time of cut | disconnecting the electrochemical element shown in FIG. 1 along the X2-X2 line | wire of FIG. It is a schematic cross section which shows the principal part at the time of cut | disconnecting the electrochemical element shown in FIG. 1 along the YY line of FIG. FIG. 5 is an enlarged view of a region R shown in FIG. 4. It is a schematic cross section which shows an example of the basic composition of the film used as the constituent material of the case of the electrochemical element shown in FIG. It is a schematic cross section which shows another example of the basic composition of the film used as the constituent material of the case of the electrochemical element shown in FIG. It is a schematic cross section which shows another one Embodiment of the electrochemical element of this invention. It is a schematic cross section which shows the internal structure of the conventional electrochemical element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A ... Electrochemical element (electric double layer capacitor), 10 ... Anode, 12 ... Anode lead wire, 14 ... Insulator, 20 ... Cathode, 22 ... Cathode lead wire, 15 ... Anode collector 16, 17 ... current collector, 18 ... cathode current collector, 24 ... insulator, 30 ... spacer, 40 ... separator, 50, 50A ... case, 61, 62, 63 ... element body, 70 ... ·gasket.

Claims (6)

2 having a configuration including a plate-like first electrode and a plate-like second electrode facing each other, and a plate-like separator disposed between the first electrode and the second electrode. With the above body,
A plate-like current collector disposed between each of the two or more element bodies;
An electrolyte solution;
A case containing the two or more element bodies, the current collector, and the electrolyte solution in a sealed state;
Have
The first electrode and the second electrode are composed of a porous layer made of a porous body,
The separator is made of an insulating porous body,
The electrolyte solution is at least partially contained in the first electrode, the second electrode, and the separator,
The two or more element bodies are electrically connected in series;
The volume A at 25 ° C. and 1 atm of the electrolyte solution filled in the case, the total X of the void volumes in the first electrode of the two or more element bodies, and the first of the two or more element bodies. The sum Y of the void volume in the electrode of 2 and the sum Z of the void volume in the separator of the two or more element bodies satisfy the condition represented by the following formula (1):
An electrochemical element characterized by the above.
0.95 ≦ {A / (X + Y + Z)} ≦ 1.05 (1) The electrochemical device according to claim 1, wherein the case is formed of a flexible film. The electrochemical device according to claim 1, wherein the case is a can-shaped exterior body formed of a metal member. The electrochemical device according to any one of claims 1 to 3, wherein the porous layer is made of a porous carbon material. The porous layer of the first electrode contains an electrode active material used for an anode of a secondary battery, and
The porous layer of the second electrode contains an electrode active material used for a cathode of a secondary battery;
The electrochemical element according to any one of claims 1 to 4, wherein The first electrode and the second electrode have the same shape and size;
The area S1 of the main surface F1 of the first electrode, the area S2 of the main surface F2 of the second electrode, and the area S3 of the main surface F3 of the separator are expressed by the following formula (2). Meets and
In each element body, the maximum width Ws of the edge of the main surface F3 projecting outside from the edge of the main surface F1 or the main surface F2, and the thicknesses of the first electrode and the second electrode The thickness T1 and the thickness T2 of the current collector satisfy the condition represented by the following formula (2);
The electrochemical element according to any one of claims 1 to 5, wherein:
S3> S1 = S2 (2)
Ws ≧ (T1 + T2 / 2) (3)

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