JP2019033123A - Electrochemical device - Google Patents

Abstract

To provide an electrochemical device capable of suppressing fire caused by ignition of lithium as initial extinguishing while securing the size and weight reduction of the entire power storage device.SOLUTION: An electrochemical device 1 includes an electrode laminate 10 formed by laminating a negative electrode 12, a separator 13, and a positive electrode 11, a fire extinguishing agent 40 for generating aerosol by burning when the temperature reaches a predetermined temperature, an electrolytic solution that contains a lithium ion-containing electrolyte and in which the electrode laminate and the fire extinguishing agent are immersed, and an exterior body 20 for accommodating the electrode laminate, fire extinguishing agent, and electrolytic solution.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrochemical device, and more particularly to an electrochemical device having an initial fire extinguishing function in the device.

  For example, power storage devices having high energy density and high output characteristics have been developed for various uses such as power and power generation. Examples of such an electricity storage device include an electrochemical device containing lithium, such as a lithium ion capacitor and a lithium ion battery (see, for example, Patent Document 1).

JP 2007-67105 A

  In this type of electrochemical device, the higher the energy density and the output characteristics, the larger the current flows when an internal short circuit occurs, and the more sudden heat is generated. Such heat generation may ignite lithium and cause a fire.

  Although it is conceivable to provide a cooling system outside the electrochemical device in order to suppress the heat generation of such a device, such a cooling system leads to an increase in the size and weight of the entire apparatus.

  Therefore, an object of the present invention is to provide an electrochemical device capable of suppressing a fire due to lithium ignition by initial fire extinguishing while ensuring miniaturization and weight reduction of the entire power storage device.

  In order to solve the above-described problems, the present invention includes an electrode laminate formed by laminating a negative electrode, a separator, and a positive electrode, a fire extinguishing agent that burns to generate aerosol when a predetermined temperature is reached, and a lithium ion-containing electrolyte, There is provided an electrochemical device comprising: an electrolytic solution in which the electrode laminate and the fire extinguishing agent are immersed; and an exterior body that houses the electrode laminate, the fire extinguishing agent, and the electrolyte.

  As described above, the electrochemical device of the present invention has the greatest feature in that a fire extinguishing agent that burns to generate aerosol when reaching a predetermined temperature is incorporated in contact with the electrolytic solution.

  In the electrochemical device of the present invention having the above-described configuration, it is preferable that the negative electrode further includes a lithium source (for example, lithium foil) for doping lithium.

  In the electrochemical device of the present invention having the above-described configuration, it is preferable that the fire-extinguishing agent is provided between the separator and at least one of the positive electrode and the negative electrode.

  Further, in the electrochemical device of the present invention having the above-described configuration, the fire extinguishing agent is molded into a sheet shape, and is formed on at least one of the positive electrode side surface and the negative electrode side surface of the separator. It is preferable that it is provided.

  Moreover, in the electrochemical device of the present invention having the above-described configuration, the fire extinguishing agent contains potassium chlorate, and the DSC evaluation (100 to 400 ° C., 10 ° C./min) endothermic peak total amount is 100 J / g to It is preferably 900 J / g.

  ADVANTAGE OF THE INVENTION According to this invention, the electrochemical device which can suppress the fire by ignition of lithium by initial fire extinguishing can ensure the size reduction and weight reduction of the whole electrical storage apparatus.

It is the schematic which shows the external appearance of the lithium ion capacitor 1 which concerns on typical embodiment of this invention. It is the sectional view on the AA line of FIG. It is explanatory drawing of the process of producing the electrode unit 10 by laminating | stacking the positive electrode 11, the negative electrode 12, and a separator among the manufacturing processes of the lithium ion capacitor 1 of FIG. FIG. 2 is an explanatory diagram of a process of housing an electrode unit 10 and a lithium ion source 30 in an outer container 20 among the manufacturing processes of the lithium ion capacitor 1 of FIG. 1. FIG. 2 is an explanatory diagram of a step of injecting an electrolyte into the outer container 20 and sealing the outer container 20 among the manufacturing steps of the lithium ion capacitor 1 of FIG. 1.

  Hereinafter, a representative embodiment of the present invention will be described in detail using an example of a lithium ion capacitor with reference to the drawings. However, the present invention is not limited to the lithium ion capacitor. The present invention is not limited to these drawings. Note that the drawings are for conceptual description of the present invention, and in order to facilitate understanding, the dimensions, ratios, or numbers may be exaggerated or simplified as necessary.

  Generally, a lithium ion capacitor is an electrochemical device belonging to a hybrid capacitor. In a lithium ion capacitor, an activated carbon electrode used as an electrode of an electric double layer capacitor is used as a material constituting a positive electrode, and a carbon-based electrode used as a negative electrode of a lithium ion secondary battery is used as a material constituting a negative electrode. used. The lithium ion capacitor is used as an electricity storage device in a state where lithium is occluded (pre-doped) in advance (or before use) in the negative electrode.

  Lithium ion capacitors are roughly classified into a laminate type cell and a cylindrical type cell. Here, a laminate type lithium ion capacitor will be described as an example. However, the present invention can also be applied to a cylindrical lithium ion capacitor.

[Configuration of lithium ion capacitor]
With reference to FIG.1 and FIG.2, the structure of the lithium ion capacitor 1 which concerns on this embodiment is demonstrated. The lithium ion capacitor 1 of this embodiment is comprised including the exterior body (exterior container) 20, the electrode laminated body (electrode unit) 10, electrolyte solution, and the fire extinguishing agent 40, as shown in FIG. In the lithium ion capacitor 1, a lithium ion source 30 is used to occlude lithium ions in the negative electrode 12 included in the electrode unit 10. Hereinafter, each of these elements will be described in detail.

(Exterior container)
The exterior container 20 is an example of an exterior body, and accommodates the electrode unit 10, the fire extinguishing agent 40, and the electrolytic solution. The exterior container 20 is formed by airtightly bonding the exterior films 21 and 22 to each other at the outer peripheral edge portions 21A and 22A.

  Here, rectangular laminate films are used as the exterior films 21 and 22, but are not limited thereto. The central portions of the exterior films 21 and 22 are subjected to drawing processing, whereby an accommodation space for the electrode unit 10 is formed inside the exterior container 20. As the exterior container 20, for example, a metal exterior can can be used.

(Electrode unit)
The electrode unit 10 is an example of an electrode laminate, and is formed by laminating a negative electrode, a separator, and a positive electrode. Specifically, the electrode unit 10 is configured by alternately laminating a plurality of positive electrodes 11 and a plurality of negative electrodes 12 via separators.
Hereinafter, the individual negative electrode 12, the positive electrode 11, and the separator 13 will be described.

<Negative electrode>
The negative electrode 12 is a sheet-like electrode, and includes a negative electrode current collector 12A and a negative electrode active material 12B provided on the surface thereof. Each of the negative electrode current collectors 12 </ b> A is electrically connected to a negative electrode terminal 52 provided at one end of the outer container 20.

  The negative electrode current collector 12A is a sheet-like or thin-film-like porous material, for example, an expanded metal, a punching metal, a metal net, a foam, or a porous foil having through holes formed by etching. Specific examples of the material of the negative electrode current collector 12A include stainless steel, copper, nickel, and the like.

  The shape of the hole of the negative electrode current collector 12A can be set to, for example, a circle, a polygon such as a rectangle, or other shapes. The form and the number of the holes are appropriately set so that lithium ions in the electrolyte solution described later can move between the front and back of the electrode without being blocked by the current collector. Further, the thickness of the negative electrode current collector 12A is appropriately set from the viewpoint of, for example, output density, strength, and weight reduction.

  The negative electrode active material 12B contains an active material capable of reversibly supporting lithium ions, and retains lithium ions by doping described later. As the negative electrode active material 12B, for example, graphite (graphite) or the like can be used.

  In the present embodiment, the negative electrode active material 12B is provided on the surface of the negative electrode current collector 12A. The thickness of the negative electrode active material 12B is set in consideration of the balance with the thickness of the positive electrode 11 so that a sufficient energy density is ensured for the obtained lithium ion capacitor 1.

  The negative electrode active material 12B is formed, for example, by preparing a slurry in which a negative electrode active material powder and a binder are dispersed in an aqueous medium or an organic solvent, applying the slurry to the surface of the negative electrode current collector 12A, and drying the slurry. Is done. Alternatively, the slurry may be formed into a sheet shape in advance, and the resulting molded body may be attached to the surface of the negative electrode current collector 12A. In addition, an electroconductive auxiliary agent may be used as needed.

  Examples of the binder include rubber-based binders such as styrene butadiene rubber (SBR), fluorine-based resins such as acrylic binders, polytetrafluoroethylene and polyvinylidene fluoride, and thermoplastic resins such as polypropylene and polyethylene. The usage-amount of a binder may be suitably set with the kind of negative electrode active material 12B, an electrode shape, etc.

  As the conductive auxiliary agent, for example, acetylene black, metal powder, or the like may be used. The amount of the conductive powder used is appropriately set according to the electrical conductivity of the negative electrode active material 12B, the electrode shape, and the like.

<Positive electrode>
The positive electrode 11 is a sheet-like electrode, and includes a positive electrode current collector 11A and a positive electrode active material 11B provided on the surface thereof. Each of the positive electrode current collectors 11 </ b> A is electrically connected to a positive electrode terminal 51 provided at one end of the outer container 20.

  The positive electrode current collector 11A is a sheet-like or thin-film-like porous material, for example, an expanded metal, a punching metal, a metal net, a foam, or a porous foil in which through holes are formed by etching. Examples of the material of the positive electrode current collector 11A include aluminum and stainless steel.

  The shape of the hole of the positive electrode current collector 11A can be set to, for example, a circle, a polygon such as a rectangle, or other shapes. The form and the number of the holes are appropriately set so that lithium ions in the electrolyte solution described later can move between the front and back of the electrode without being blocked by the current collector. Further, the thickness of the positive electrode current collector 11A is appropriately set from the viewpoint of, for example, output density, strength, and weight reduction.

  The positive electrode active material 11B contains a positive electrode active material 11B that can reversibly carry anions. As the positive electrode active material 11B, for example, activated carbon, carbon nanotube, or the like can be used.

  The positive electrode active material 11B can be formed by a method similar to that of the negative electrode active material 12B. Moreover, the thickness of the positive electrode active material 11B is designed in balance with the thickness of the negative electrode active material 12B so that a sufficient energy density is ensured in the obtained lithium ion capacitor 1.

<Separator>
The separator 13 is a sheet material interposed between the positive electrode 11 and the negative electrode 12. As the separator 13, a porous body made of a woven fabric or a non-woven fabric that is durable with respect to the electrolytic solution, the positive electrode active material 11 </ b> B, and the negative electrode active material 12 </ b> B can be used. As a material of the separator 13, for example, a thermoplastic resin such as cellulose (paper), polyethylene, polypropylene, cellulose / rayon, engineer plastic / super engineer plastic, or glass fiber can be used.

  Here, a layer of the fire extinguishing agent 40 is formed on the surface of the separator 13 of the present embodiment. The fire extinguishing agent 40 burns and generates aerosol when it reaches a predetermined temperature. Here, the predetermined temperature may be set to 150 ° C. to 180 ° C. based on the ignition temperature of lithium metal, for example. Further, the layer of the fire extinguishing agent 40 is formed so as to substantially cover the surface of the separator 13 and has a substantially uniform thickness.

  In the present embodiment, the fire extinguishing agent 40 is formed on both surfaces of the separator 13, but the fire extinguishing agent 40 may be disposed on one surface of the separator 13. Moreover, the fire extinguishing agent 40 does not need to be provided in all the separators 13 and may be provided in a part of the separators 13. That is, when viewed from the normal direction of the surface of the separator 13, the layer of the fire extinguishing agent 40 is present discontinuously, for example, in the form of islands even if the layer of the fire extinguishing agent 40 exists continuously over the entire surface of the separator 13. Also good. From the viewpoint of obtaining the effects of the present invention more reliably, it is preferable that the separator 13 exists continuously over the entire surface.

  Moreover, the fire extinguishing agent 40 does not need to adhere to the separator 13 and may be interposed between the separator 13 and the electrode independently of the separator 13. That is, the fire extinguishing agent 40 may be disposed at a position in contact with the electrolytic solution in the outer container 20.

  It is desirable that the fire extinguishing agent 40 does not dissolve even when it comes into contact with the electrolytic solution and does not change the chemical properties. For example, it is preferable that the fire extinguishing agent 40 contains potassium chlorate and has a DSC evaluation (100 to 400 ° C., 10 ° C./min) endothermic peak total amount of 100 J / g to 900 J / g. The specific composition of the fire extinguishing agent 40 will be described later.

<Lithium ion source>
A film-like lithium ion source 30 may be housed in the outer container 20 together with the electrode unit 10. The lithium ion source 30 is used to dope lithium into the negative electrode, and includes, for example, a foil or sheet-like lithium metal 31 and a lithium electrode current collector 32. The lithium metal 31 is attached to the lithium electrode current collector 32, and the lithium electrode current collector 32 is electrically connected to the negative electrode terminal 52.

  The dimension (volume) of the lithium metal 31 is appropriately determined in consideration of the amount of lithium ions doped into the negative electrode active material 12B. For example, the doping amount of lithium ions is set so that the potential of the positive electrode 11 becomes a predetermined value (for example, 2.0 V or less) when both electrodes are short-circuited.

  As the lithium electrode current collector 32, it is preferable to use a material having a porous structure similar to the electrode current collector described above so that the lithium metal 31 is easily attached and lithium ions pass as necessary. However, the lithium electrode current collector 32 is made of a material that does not react with the lithium metal 31, such as stainless steel.

<Electrode terminal>
A plate-like positive electrode terminal 51 is provided at one end of the outer container 20 so as to protrude from the inside of the outer container 20 to the outside. In addition, a plate-like negative electrode terminal 52 is provided at the other end of the outer container 20 so as to protrude from the inside of the outer container 20 to the outside of the outer container 20. However, the positive electrode terminal 51 and the negative electrode terminal 52 may be provided on the same side of the outer container 20.

  As the negative electrode terminal 52, a metal material such as copper or nickel, or a metal material having a surface such as nickel plating applied on the surface thereof can be used.

<Electrolyte>
The exterior container 20 is filled with an electrolytic solution. The electrolytic solution includes a lithium ion-containing electrolyte and an organic solvent, and the electrode unit 10 is immersed therein. The electrolytic solution is preferably non-aqueous.

  The lithium salt constituting the electrolyte is not particularly limited as long as it can transfer lithium ions, does not cause electrolysis even under a high voltage, and can stably exist. For example, a lithium salt having an imide structure can be employed. For example, lithium bis (fluorosulfonyl) imide [LiFSI], lithium bis (trifluoromethanesulfonyl) imide [LiTFSI], lithium bis (pentafluoroethanesulfonyl) ) Imido [LiBETI] and the like. In addition, these lithium salts may use only 1 type, or may use 2 or more types. Of these, lithium salts having an imide structure are preferable.

  Specific examples of the organic solvent include ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), acetonitrile, Acrylonitrile, adiponitrile, valeronitrile, isobutyronitrile, γ-butyrolactone, γ-valerolactone, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, dimethyl ether, triglyme, ethyl alcohol, ethylene glycol, methyl acetate, propyl acetate, trimethyl phosphate , Dimethyl sulfate, dimethyl sulfite, N-methyl-2-pyrrolidone, ethylenediamine, dimethylsulfone, 3-sulfolene, methylethyl Examples include ketones. These organic solvents can be used individually or in mixture of 2 or more types.

  The electrolytic solution is prepared by mixing the above electrolyte and organic solvent in a sufficiently dehydrated state, but the concentration of the electrolyte in the electrolytic solution is appropriately set so that the internal resistance due to the electrolytic solution is reduced. Good. Moreover, you may add an additive suitably to electrolyte solution.

<Fire extinguishing agent>
Here, the composition which comprises the fire extinguishing agent used by this embodiment is demonstrated. As such a fire extinguishing agent composition, various types can be used as described below.

  The fire extinguishing agent 40 in this embodiment contains, for example, 20 to 50% by mass of fuel (component A) and 80 to 50% by mass of chlorate (component B), and further the total amount of the fuel and chlorate is 100. 6-1000 mass parts potassium salt (C component) is contained with respect to a mass part, and thermal decomposition start temperature is the range of more than 90 degreeC-450 degreeC.

  The fuel as the A component is a component for generating aerosol (potassium radical) derived from the potassium salt of the C component by generating thermal energy by combustion together with the chlorate as the B component.

  Examples of such component A fuels include dicyandiamide, nitroguanidine, guanidine nitrate, urea, melamine, melamine cyanurate, Avicel, guar gum, sodium carboxymethylcellulose, carboxymethylcellulose potassium, carboxymethylcellulose ammonium, nitrocellulose, aluminum, boron, magnesium. , Magnalium, zirconium, titanium, titanium hydride, tungsten and silicon are preferred.

  The B component chlorate is a powerful oxidant, and is a component for generating thermal energy by combustion together with the A component fuel to generate aerosol (potassium radical) derived from the C component potassium salt.

  The B component chlorate is preferably selected from at least one of potassium chlorate, sodium chlorate, strontium chlorate, ammonium chlorate and magnesium chlorate.

Here, the content ratio in 100 mass% of the fuel of component A and the chlorate of component B is as follows.
A component: 20-50 mass%
Preferably 25-40 mass%
More preferably 25 to 35% by mass
B component: 80-50 mass%
Preferably 75-60 mass%
More preferably 75 to 65% by mass

  Next, the potassium salt of the C component is a component for generating an aerosol (potassium radical) by heat energy generated by the combustion of the A component and the B component.

  Examples of the potassium salt of component C include potassium acetate, potassium propionate, monopotassium citrate, dipotassium citrate, tripotassium citrate, ethylenediaminetetraacetic acid monohydrogentripotassium, ethylenediaminetetraacetic acid dipotassium dihydrogen, ethylenediaminetetraacetate. Preference is given to at least one selected from tripotassium acetate hydrogen acetate, tetrapotassium ethylenediaminetetraacetate, potassium hydrogen phthalate, dipotassium phthalate, potassium hydrogen oxalate, dipotassium oxalate and potassium bicarbonate.

  It is preferable that the content rate of C component is 6-1000 mass parts with respect to 100 mass parts of total amounts of A component and B component, More preferably, it is 10-900 mass parts.

  Furthermore, the fire-extinguishing agent composition of the present embodiment has a thermal decomposition start temperature in the range of more than 90 ° C. to 450 ° C., preferably 150 ° C. to 260 ° C. The thermal decomposition starting temperature is particularly preferably 150 ° C. to 180 ° C. in relation to the initial extinguishing of a fire caused by lithium metal. Such a range of the thermal decomposition start temperature can be prepared by combining the A component, the B component, and the C component in the above ratio.

  In addition, what is necessary is just to produce molded bodies, such as a sheet | seat of a fire extinguishing agent, mixing each component of said fire extinguishing agent composition, shape | molding in a sheet form, controlling temperature, and drying suitably.

  The fire extinguishing agent composition of the present embodiment is derived from the C component by satisfying the above thermal decomposition start temperature range so that the A component and the B component are automatically ignited and burned in response to the heat at the time of the fire. It can extinguish fire by generating aerosol (potassium radical).

[Lithium ion capacitor manufacturing process]
With reference to FIGS. 3 to 5, a manufacturing process of the lithium ion capacitor 1 having the above-described configuration will be described.

  As shown in FIG. 3, the electrode unit 10 is prepared. Specifically, first, the positive electrode 11, the negative electrode 12, and the separator 13 are prepared. At that time, a layer of the fire extinguishing agent 40 may be formed on the surface (one side or both sides) of the separator 13.

  And the positive electrode 11 and the negative electrode 12 are laminated | stacked through the separator 13, and the electrode unit 10 is produced. At this time, when the layer of the fire extinguishing agent 40 is not formed on the surface of the separator 13, for example, when the sheet-like extinguishing agent 40 is interposed between the separator 13 and each of the positive electrode 11 and the negative electrode 12, for example. Good.

  Next, as shown in FIG. 4, the electrode unit 10 and the lithium ion source 30 are accommodated in the outer container 20. At that time, the positive electrode current collector 11A constituting the electrode unit 10 is connected to the positive electrode terminal 51, and the negative electrode current collector 12A is connected to the negative electrode terminal 52.

  Thereafter, as shown in FIG. 5, the exterior container 20 is filled with an electrolytic solution, and the exterior container 20 is sealed. Thereby, the lithium ion capacitor 1 is obtained.

  In the lithium ion capacitor 1 manufactured in this manner, the outer container 20 is filled with an electrolyte solution that can supply lithium ions, and therefore, when left for an appropriate period, the lithium ion capacitor 1 was released from the lithium ion source 30. Lithium ions are doped into the negative electrode 12.

[Effect of this embodiment]
In the present embodiment, the extinguishing agent 40 is enclosed with the electrode unit 10 in the exterior container 20. When the fire extinguishing agent 40 reaches a predetermined temperature (for example, 150 ° C. to 180 ° C.), it burns and generates aerosol. Therefore, even if the lithium metal used for the electrode ignites due to, for example, a short circuit between the positive electrode 11 and the negative electrode 12, it is extinguished by the aerosol from the extinguishing agent 40. Thereby, the further temperature rise in a container is suppressed and initial fire extinguishing becomes possible.

  Further, when the fire extinguishing agent 40 is provided between the separator 13 and the positive electrode 11 and the negative electrode 12, the fire extinguishing agent 40 is adjacent to the positive electrode 11 and the negative electrode 12. Therefore, the fire extinguishing agent 40 adjacent to the specific electrode whose temperature has risen due to the short circuit supplies the aerosol around the electrode, so that rapid initial fire fighting can be realized.

  Moreover, the manufacturing process of the lithium ion capacitor 1 is simplified by the fire-extinguishing agent 40 being molded into a sheet and provided on both sides or one side of the separator 13. Further, forgetting to put in the fire extinguishing agent 40 can be prevented, so that the quality of the lithium ion capacitor 1 can be ensured.

  As mentioned above, although typical embodiment of this invention was described, this invention is not limited to these, A various design change is possible and they are also contained in this invention.

For example, the electrode unit 10 may be of a configuration other than the stacked unit, for example, a wound type unit in which the positive electrode 11 and the negative electrode 12 are wound in a state of being stacked via the separator 13.
Moreover, the electrochemical device of the present invention is not limited to a lithium ion capacitor, and can be configured as, for example, a lithium ion secondary battery.

  The lithium ion source 30 does not need to be stored in the outer container 20. For example, when lithium ions are injected into the outer container 20 in the manufacturing process, the lithium ion source does not need to be a component of the electrochemical device.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In these examples and comparative examples, lithium ion capacitors having the structures of FIGS. 1 to 4 were produced as follows.

<< Example >>
(1) Production of sheet-like negative electrode 95 parts by mass of graphite as a negative electrode active material, 1 part by mass of SBR as a binder, 1 part by mass of carboxymethyl cellulose (CMC) as a thickener, and 100 parts by mass of water as a solvent are mixed. A negative electrode slurry was prepared.
Next, a 10 μm-thick copper foil (porous foil) was used as the negative electrode current collector, and the negative electrode slurry was applied to the negative electrode current collector and dried to prepare a sheet-like negative electrode. The coating amount of the negative electrode slurry was adjusted so that the mass of graphite after drying was 4 mg / cm ² .

(2) Preparation of sheet-like positive electrode 90 parts by mass of powdered activated carbon as a positive electrode active material, 6 parts by mass of polyacrylic acid (polyacrylic acid sodium neutralized salt), 15 parts by mass of acetylene black as a conductive additive, solvent As a mixture, 345 parts by mass of water was mixed to prepare a positive electrode slurry.
Next, an aluminum foil (porous foil) having a thickness of 15 μm was used as the positive electrode current collector, and the positive electrode slurry was applied to the positive electrode current collector and dried to prepare a sheet-like positive electrode. The coating amount of the positive electrode slurry was adjusted so that the mass of the activated carbon after drying was 4 mg / cm ² .

(3) Preparation of sheet fire extinguishing agent

30 parts by mass of sodium carboxymethyl cellulose, 370 parts by mass of KClO and 10 parts by mass of tripotassium citrate were mixed to prepare a fire extinguishing agent composition. This fire-extinguishing agent composition was molded into a sheet shape while controlling the ambient temperature, and air-dried to prepare a sheet-like fire extinguishing agent. The obtained sheet-shaped fire extinguishing agent has a thickness of 0.5 mm, a total endothermic peak of potassium salt (J / g) @ DSC of 10 ° C./min when heated (100 to 440 ° C. range), and an apparent density of 2. It was 0 g / cm ³ .

(4) Preparation of electrolyte solution As a solvent, a mixed solvent of 35% by volume of ethylene carbonate (EC), 35% by volume of dimethyl carbonate (DMC) and 30% by volume of ethyl methyl carbonate (EMC) was used. An electrolyte solution was prepared by adding 1 mol / l of sulfonylimide) (LiFSI).

(5) Production of Lithium Ion Capacitor The positive electrode and the negative electrode produced as described above were each punched out into a rectangle of 60 mm × 40 mm, leaving a 40 mm × 40 mm coating film and 20 mm × 40 mm on one end side of the long side. The coating film in the area was peeled off and a current collecting tab was attached. And the electrode laminated body was produced by making the coating-film part of a positive electrode and a negative electrode face each other in the state which interposed the separator made from a cellulose of 20 micrometers in thickness. However, at this time, in the electrode laminate, a sheet-shaped fire extinguishing agent cut to a size of 40 mm × 40 mm was disposed on both sides of each separator.
The electrode laminate and the lithium metal foil for lithium pre-doping were encapsulated in an aluminum laminate foil, and the electrolyte prepared as described above was injected and sealed to produce the lithium ion capacitor of the present invention.

≪Comparative example≫
A comparative lithium ion capacitor was produced in the same manner as in the above example except that no sheet-like fire extinguishing agent was disposed in the electrode laminate.

[Evaluation test]
In the lithium ion capacitor of the present invention and the comparative lithium ion capacitor produced as described above, after lithium pre-doping, charge / discharge, and aging, at room temperature (25 ° C.), a cut-off voltage: 2.5 to When the internal resistance and discharge capacity were measured at 3.5 V and a measurement current of 10 C, all exhibited equivalent initial performance.
Then, when an iron rod was pierced and the positive electrode and the negative electrode were short-circuited to evaluate whether or not to ignite, the lithium ion capacitor of the present invention did not ignite, whereas the comparative lithium ion capacitor ignited. It was. This is because when a positive electrode and a negative electrode are short-circuited in a lithium ion capacitor and ignited, the A component and B component in the fire extinguishing agent are automatically ignited and burned, and an aerosol derived from the C component ( It is considered that (potassium radical) was generated and the subsequent ignition was effectively suppressed (fire extinguishing).

  From the above Examples and Comparative Examples, in the lithium ion capacitor that is the electrochemical device of the present invention, the fire extinguishing agent is built in a state of being in contact with the electrolytic solution. It turns out that the function is fully demonstrated.

1 Lithium ion capacitor (electrochemical device),
10 ... Electrode unit,
11 ... positive electrode,
12 ... negative electrode,
13 ... Separator,
20 ... exterior container,
30 ... lithium ion source,
40 ... extinguishing agent.

Claims (5)

An electrode laminate formed by laminating a negative electrode, a separator and a positive electrode;
A fire extinguishing agent that burns and generates aerosol when it reaches a certain temperature;
An electrolyte containing a lithium ion-containing electrolyte and immersing the electrode laminate and the fire extinguishing agent;
An exterior body that houses the electrode laminate, the fire extinguishing agent, and the electrolyte;
An electrochemical device comprising: Further comprising a lithium source for doping the negative electrode with lithium;
The electrochemical device according to claim 1. The fire extinguishing agent is provided between the separator and at least one of the positive electrode and the negative electrode;
The electrochemical device according to claim 1 or 2. The fire extinguishing agent is molded into a sheet and is provided on at least one of the positive electrode side surface and the negative electrode side surface of the separator;
The electrochemical device according to any one of claims 1 to 3. The fire extinguishing agent comprises potassium chlorate,
DSC evaluation (100 to 400 ° C., 10 ° C./minute heating) endothermic peak total amount is 100 J / g to 900 J / g,
The electrochemical device according to claim 1, wherein: