JP2017022172A - Electrode manufacturing method and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode manufacturing method and a power storage device that can suppress the amount of gas occurring when the power storage device is held under a charged state in spite of use of an active material having a small particle diameter.SOLUTION: A method of manufacturing an electrode constituting a power storage device contains a step of doping alkali metal into an active material having a 50% volume cumulative diameter D50 of 10 μm or less in electrolytic solution containing an alkali metal salt before the power storage device is assembled. For example, a carbon material may be listed up as the active material. It is preferable that the specific surface area of the active material is equal to 5 m/g or more. It is preferable that at least a part of the alkali metal salt is an alkali metal salt or lithium salt which contains a sulfonyl imide anion having a fluoro group.SELECTED DRAWING: None

Description

  The present invention relates to an electrode manufacturing method and an electricity storage device.

2. Description of the Related Art In recent years, electronic devices have been remarkably reduced in size and weight, and accordingly, there has been an increasing demand for downsizing and weight reduction of batteries used as power sources for driving the electronic devices.
In order to satisfy such demands for reduction in size and weight, non-aqueous electrolyte secondary batteries (an example of an electricity storage device) typified by lithium ion secondary batteries have been developed. Moreover, a lithium ion capacitor is known as an electricity storage device corresponding to an application that requires high energy density characteristics and high output characteristics. Further, a sodium ion type power storage device using sodium which is cheaper and more resource-efficient than lithium is also known.

  Such an electricity storage device is required to have a low internal resistance. In order to meet this demand, Patent Document 1 and Patent Document 2 propose using a negative electrode active material having a relatively small 50% volume cumulative diameter D50 for the negative electrode constituting the electricity storage device.

JP2013-258392A International Publication No. 2014/156892 Pamphlet

However, an electricity storage device using a negative electrode active material with a small particle size has a problem that the amount of gas generated when held in a charged state is large.
The present invention provides an electrode manufacturing method and an electricity storage device capable of suppressing the amount of gas generated when the electricity storage device is held in a charged state even when an active material having a small particle diameter is used. Objective.

  The method for producing an electrode of the present invention is a method for producing an electrode constituting an electricity storage device, and before assembling the electricity storage device, the 50% volume cumulative diameter D50 is 10 μm or less in an electrolyte containing an alkali metal salt. A step of doping the active material with an alkali metal.

  If the electrode manufactured by the electrode manufacturing method of the present invention is used, the amount of gas generated when the electric storage device is held in a charged state can be suppressed even if the 50% volume cumulative diameter D50 of the active material is 10 μm or less. .

An embodiment of the present invention will be described.
1. Electrode Manufacturing Method The electrode manufacturing method of the present invention includes a step of doping alkali metal into an active material having a 50% volume cumulative diameter D50 of 10 μm or less in an electrolytic solution containing an alkali metal salt.

  The electrode produced according to the present invention may be a positive electrode or a negative electrode. In the method for producing an electrode of the present invention, when producing a positive electrode, the positive electrode active material is doped with an alkali metal, and when producing a negative electrode, the negative electrode active material is doped with an alkali metal.

  The active material is not particularly limited as long as the 50% volume cumulative diameter D50 is 10 μm or less, and is an electrode active material applicable to an electricity storage device using insertion / extraction of alkali metal ions. An active material may be sufficient and a positive electrode active material may be sufficient.

  The negative electrode active material is not particularly limited. For example, carbon materials such as graphite, graphitizable carbon, non-graphitizable carbon, composite carbon material in which graphite particles are coated with a carbide of pitch or resin; lithium and alloys Examples thereof include metals or metalloids such as Si and Sn that can be formed, and materials containing these oxides. Specific examples of the carbon material include carbon materials described in JP2013-258392A. Specific examples of the metal or metalloid capable of being alloyed with lithium or a material containing these oxides include materials described in JP-A-2005-123175 and JP-A-2006-107795.

  Examples of the positive electrode active material include alkali metal transition metal composite oxides such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, sodium cobalt oxide, sodium nickel oxide, and sodium manganese oxide. .

  Both the positive electrode active material and the negative electrode active material may be composed of a single material, or may be a mixture of two or more materials. In the case of a mixture of two or more substances, the 50% volume cumulative diameter D50 of at least one of them may be 10 μm or less. In the method for producing an electrode of the present invention, the active material is preferably a negative electrode active material, particularly a carbon material, from the viewpoint that a desired effect is remarkably recognized. The desired effect means an effect capable of suppressing the amount of gas generated when the power storage device is held in a charged state.

  In the present invention, the 50% volume cumulative diameter D50 of the active material is 10 μm or less, but in order to obtain an electricity storage device having a lower internal resistance, it is preferably 8 μm or less, and particularly preferably 5 μm or less.

  The 50% volume cumulative diameter D50 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and particularly preferably 1 μm or more from the viewpoint of ease of manufacturing the electrode. In general, when the particle size of the active material is reduced, the amount of gas generated when the electricity storage device is held in a charged state tends to increase. Can be suppressed. The 50% volume cumulative diameter D50 is a value measured by a laser diffraction / scattering method.

  In order to obtain an electricity storage device having a lower internal resistance, it is preferable to use an active material having a pore diameter of 50 to 400 nm and a large macropore volume. More specifically, the macropore volume is 0.05 cc / g or more. It is preferable to use the active material.

  The macropore volume of the active material is preferably 0.40 cc / g or less, more preferably 0.35 cc / g or less, and 0.30 cc / g or less from the viewpoint of electrode strength and cycle characteristics. It is particularly preferred.

  In the present invention, the macropore volume refers to a nitrogen adsorption isotherm obtained by a nitrogen adsorption method at a temperature of 77 K using an automatic specific surface area / pore distribution measuring device BELSORP-miniII manufactured by Nippon Bell Co., Ltd. DH (Dollimore Heal) It means the volume of pores having a pore diameter in the range of 50 to 400 nm, which is obtained by analyzing by the method.

  In order to obtain an electricity storage device having a lower internal resistance, it is preferable to use an active material having a large mesopore volume. More specifically, an active material having a mesopore volume of 0.005 cc / g or more is used. It is more preferable to use an active material having a mesopore volume of 0.010 cc / g or more.

  The mesopore volume of the active material is preferably 0.080 cc / g or less, and particularly preferably 0.050 cc / g or less, from the viewpoint of enhancing a desired effect. The desired effect means an effect capable of suppressing the amount of gas generated when the power storage device is held in a charged state.

  In the present invention, the mesopore volume is a DH method that analyzes a nitrogen adsorption isotherm obtained by a nitrogen adsorption method at a temperature of 77K using an automatic specific surface area / pore distribution measuring device BELSORP-miniII manufactured by Nippon Bell Co., Ltd. It means the volume of pores having a pore diameter in the range of 2 to 50 nm.

In order to obtain an electricity storage device having a lower internal resistance, it is preferable to use an active material having a large specific surface area. More specifically, it is preferable to use an active material having a specific surface area of 5 m ² / g or more. It is particularly preferable to use an active material having a specific surface area of 10 m ² / g or more.

The specific surface area of the active material, from the viewpoint of electrode strength is preferably ^{50 m} 2 / g or less, and particularly preferably ^{30 m} 2 / g. The specific surface area is a value measured by a nitrogen adsorption method.

  In general, when the macropore volume, mesopore volume, and specific surface area of the active material increase, the amount of gas generated when the power storage device is held in a charged state tends to increase. If the method is used, such a problem can be suppressed.

As an alkali metal doped into an active material having a 50% volume cumulative diameter D50 of 10 μm or less, lithium or sodium is preferable, and lithium is particularly preferable.
The electrolytic solution containing the alkali metal salt preferably contains an organic solvent and a lithium salt or sodium salt dissolved therein. Examples of the anion moiety constituting the alkali metal salt include phosphorus anions having a fluoro group such as PF ₆ ⁻ , PF ₃ (C ₂ F ₅ ) ₃ ⁻ , PF ₃ (CF ₃ ) ₃ ⁻ , and the like; BF ₄ ⁻ , Boron anions having a fluoro group or a cyano group such as BF ₂ (CF) ₂ ⁻ , BF ₃ (CF ₃ ) ⁻ and B (CN) ₄ ^— ; N (FSO ₂ ) ₂ ⁻ , N (CF ₃ SO ₂ ) _{2 ^{-, N (C 2 F 5}} SO 2) 2 - sulfonyl imide anion having a fluoro group such as; _{CF 3} SO 3 ^- is an organic sulfonate anion having a fluoro group and the like. Among these, a sulfonylimide anion having a fluoro group is preferable from the viewpoint of enhancing a desired effect. The desired effect means an effect capable of suppressing the amount of gas generated when the power storage device is held in a charged state. The electrolytic solution may contain a single alkali metal salt or two or more alkali metal salts.

  As the organic solvent, an aprotic organic solvent is preferable. Examples of the aprotic organic solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, acetonitrile, dimethoxyethane, tetrahydrofuran, dioxolane, methylene chloride, sulfolane and the like. It is done.

  As the organic solvent, ionic liquids such as quaternary imidazolium salts, quaternary pyridinium salts, quaternary pyrrolidinium salts, and quaternary piperidinium salts can also be used. The organic solvent may be composed of a single component or a mixed solvent of two or more components.

  The concentration of alkali metal ions (alkali metal salt) in the electrolytic solution is preferably 0.1 mol / L or more, more preferably in the range of 0.5 to 1.5 mol / L. When it is within this range, the alkali metal doping proceeds efficiently.

  The electrolytic solution containing the alkali metal salt further includes vinylene carbonate, vinyl ethylene carbonate, 1-fluoroethylene carbonate, 1- (trifluoromethyl) ethylene carbonate, succinic anhydride, maleic anhydride, propane sultone, diethyl sulfone, and the like. The additive may be contained.

The step of doping the active material with the alkali metal in the electrolytic solution containing the alkali metal salt is not particularly limited, and examples thereof include the following doping step A and doping step B. The doping amount is preferably 70 to 95% of the theoretical capacity when doping the negative electrode active material of the lithium ion capacitor, and when doping the lithium negative electrode active material of the lithium ion secondary battery, Preferably it is 10 to 30% with respect to the theoretical capacity.
(Doping process A)
First, a layer containing an active material before doping with an alkali metal (hereinafter referred to as a precursor layer) is formed on a current collector. The precursor layer and the current collector are combined into an electrode precursor. This electrode precursor is brought into electrochemical contact with an alkali metal source in an electrolyte containing an alkali metal salt. At this time, the active material contained in the precursor layer is doped with an alkali metal, and the electrode precursor becomes an electrode.

  If the doping step A is used, after the doping step A, the manufactured electrode can be used as it is (without passing through a step of forming a layer containing an active material on the current collector, etc.) as an electrode of an electricity storage device. it can.

  The precursor layer can be produced, for example, by preparing a slurry containing an active material before doping with an alkali metal, a binder, and the like, applying the slurry on a current collector, and drying the slurry.

  Examples of the binder include rubber-based binders such as styrene-butadiene rubber (SBR) and NBR; fluorine-based resins such as polytetrafluoroethylene and polyvinylidene fluoride; polypropylene, polyethylene, disclosed in JP2009-246137A Fluorine-modified (meth) acrylic binder as described above.

  The slurry may contain other components in addition to the active material and the binder. Other components include, for example, conductive agents such as carbon black, graphite, vapor-grown carbon fiber, and metal powder; carboxyl methyl cellulose, its Na salt or ammonium salt, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, Examples include thickeners such as oxidized starch, phosphorylated starch, and casein.

Although the thickness of the said precursor layer is not specifically limited, For example, 5-500 micrometers, Preferably it is 10-200 micrometers, Most preferably, it is 10-100 micrometers.
As the current collector, for example, a metal foil such as copper, nickel, and stainless steel is preferable. Further, the current collector may be one in which a conductive layer mainly composed of a carbon material is formed on the metal foil. The thickness of the current collector can be, for example, 5 to 50 μm.

  The form of the alkali metal supply source is not particularly limited. For example, an alkali metal plate, an alkali metal alloy plate, or the like can be used as the alkali metal supply source. These thicknesses can be set to 0.03 to 3 mm, for example. The alkali metal supply source is preferably disposed on the conductive substrate. The conductive substrate may be porous. Examples of the material of the conductive substrate include copper, stainless steel, nickel, and the like.

  Examples of a method of bringing the electrode precursor and the alkali metal supply source into electrochemical contact include, for example, a method of short-circuiting the electrode precursor and the alkali metal supply source in an electrolyte solution containing an alkali metal salt, The method of supplying a direct current between an electrode precursor and an alkali metal supply source in the electrolyte solution containing salt is mentioned.

  As a method for short-circuiting the electrode precursor and the alkali metal supply source in the electrolyte containing the alkali metal salt, for example, the current collector is used as one terminal, and the conductive substrate on which the alkali metal supply source is arranged is the other. As a terminal, there is a method in which both terminals are electrically connected by a conductor such as a metal wire to cause a short circuit. The time for short-circuiting can be appropriately set according to the area, thickness, etc. of the precursor layer, and can be, for example, 1 to 1000 hours, preferably 5 to 500 hours.

Further, as a method of passing a direct current between an electrode precursor and an alkali metal supply source in an electrolyte containing an alkali metal salt, for example, a positive terminal of a direct current stabilized power source is connected to an alkali metal supply source. There is a method of connecting a conductive base material arranged and connecting a negative terminal of a direct current stabilized power source to a current collector to energize. The current at the time of energization can be appropriately set according to the area, thickness, etc. of the precursor layer.
(Doping process B)
In an electrolytic solution containing an alkali metal salt, the active material itself is brought into contact with an alkali metal supply source to dope the active material with an alkali metal. A specific method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2012-209195.

  The method described in the publication includes a mixture containing at least one solvent selected from the group consisting of ethylene carbonate, propylene carbonate, diethyl carbonate, and dimethyl carbonate, a lithium salt, metallic lithium, and an active material. In this method, the active material is doped with lithium by bringing the material into contact with the metallic lithium.

In the method described in the publication, the lithium salt is composed of LiBF ₄ , LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiC ₄ BO ₈ , (C ₂ F ₅ SO ₂ ) ₂ NLi, and (FSO ₂ ) ₂ NLi. At least one selected from the group can be mentioned. Moreover, as the metal lithium, lithium metal powder coated with Li ₂ CO ₃ or lithium metal foil can be used.

In the method described in the publication, when dopeing, the electrode active material and the metallic lithium can be brought into electrical contact by applying ultrasonic vibration to the mixture.
An electrode can be manufactured by preparing a slurry containing an active material doped with an alkali metal in the doping step B, a binder, and the like, applying the slurry on a current collector, and drying the slurry. The electrode includes an active material layer containing the active material, the binder, and the like, and a current collector.

The thickness of the active material layer is not particularly limited, but is, for example, 5 to 500 μm, preferably 10 to 200 μm, and particularly preferably 10 to 100 μm.
Examples of the binder include the same binders as those contained in the slurry used in the dope step A. The slurry may contain other components in addition to the active material and the binder. Examples of other components include the same components as those contained in the slurry used in the dope step A. The material, thickness, etc. of the current collector can also be the same as the current collector used in the doping step A.

  The electrode manufacturing method of the present invention is suitable for manufacturing a negative electrode included in an alkali ion type electricity storage device, and more suitable for manufacturing a negative electrode included in an alkali ion type capacitor or a secondary battery. It is particularly suitable for manufacturing a negative electrode included in a secondary battery.

  When the electrode obtained by the method for producing an electrode of the present invention is used for a lithium ion secondary battery, the density of the active material layer is preferably 1.50 to 2.00 g / cc, particularly preferably 1.60. ˜1.90 g / cc.

  Moreover, when using the electrode obtained by the manufacturing method of the electrode of this invention for a lithium ion capacitor, the density of the active material layer becomes like this. Preferably it is 0.50-1.50 g / cc, Most preferably, it is 0.70. ~ 1.20 g / cc.

2. Electric storage device The electric storage device of the present invention includes a positive electrode, a negative electrode, and an electrolyte, and the negative electrode is manufactured by the electrode manufacturing method of the present invention. The electricity storage device is not particularly limited as long as it is an electricity storage device that utilizes insertion / extraction of alkali metal ions. For example, a lithium ion secondary battery, a sodium ion secondary battery, an air battery, a lithium ion capacitor Etc. Among these, a lithium ion secondary battery or a lithium ion capacitor is preferable.

  The basic configuration of the positive electrode constituting the electricity storage device of the present invention is the same as the configuration of the electrode described in the above-mentioned “electrode manufacturing method”, but as the positive electrode active material, in addition to those already exemplified, a nitroxy radical compound It is also possible to use organic active materials such as activated carbon, oxygen and the like.

  The form of the electrolyte constituting the electricity storage device of the present invention is usually a liquid electrolyte. The basic configuration of the electrolytic solution is the same as the configuration of the electrolytic solution described in the above “electrode manufacturing method”. The electrolyte may have a gel or solid form for the purpose of preventing leakage.

  The electricity storage device of the present invention can include a separator for suppressing physical contact between the positive electrode and the negative electrode. As a separator, the nonwoven fabric or porous film which uses a cellulose rayon, polyethylene, a polypropylene, polyamide, polyester, a polyimide etc. as a raw material can be mentioned, for example.

  As the structure of the electricity storage device, for example, three or more plate-like structural units composed of a positive electrode and a negative electrode and a separator interposed therebetween are laminated to form a laminate, and the laminate is enclosed in an exterior film. And a stacked cell.

  In addition, as a structure of the electricity storage device, for example, a strip-shaped structural unit composed of a positive electrode and a negative electrode, and a separator interposed therebetween is wound to form a laminated body, and the laminated body is formed into a rectangular or cylindrical container. Examples include a wound type cell that is stored.

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples. In the following examples and comparative examples, various physical properties of the active material were measured by the following methods. The negative electrode was produced in an air environment controlled at a temperature of 23 ° C. and a dew point of −40 ° C.
<Measurement of 50% volume cumulative diameter D50>
The 50% volume cumulative diameter D50 was measured using a laser diffraction / scattering particle size distribution measuring apparatus LA-950V2 manufactured by Horiba, Ltd. Hereinafter, the 50% volume cumulative diameter D50 may be simply referred to as D50.
<Measurement of macropore volume and mesopore volume>
A nitrogen adsorption isotherm was obtained by a nitrogen adsorption method at 77K using an automatic specific surface area / pore distribution measuring device BELSORP-miniII manufactured by Nippon Bell Co., Ltd. The nitrogen adsorption isotherm was analyzed by the DH method to determine the macropore volume and the mesopore volume.

At this time, the measurement mode of the automatic specific surface area / pore distribution measuring apparatus was set to “high accuracy mode”, and a standard cell of about 1.8 cm ³ was used as a sample cell. Moreover, the sample amount was weighed to an order of 10 ⁻⁴ g using an electronic balance so as to be in the range of 0.1500 to 0.2500 g. In addition, these measurements were performed about the sample (active material) vacuum-dried at 200 degreeC for 2 hours.
<Measurement of specific surface area>
A nitrogen adsorption isotherm was obtained by a nitrogen adsorption method at 77K using an automatic specific surface area / pore distribution measuring device BELSORP-miniII manufactured by Nippon Bell Co., Ltd. The nitrogen adsorption isotherm was analyzed by the BET method to determine the specific surface area. During the analysis, measurement points having a relative pressure P / P ₀ in the range of 0.05 to 0.25 were used. Moreover, the sample amount was weighed to an order of 10 ⁻⁴ g using an electronic balance so as to be in the range of 0.1500 to 0.2500 g.

Example 1
(i) Production of negative electrode active material 100 parts by mass of commercially available artificial graphite (D50: 1.5 μm, d002 plane interval by X-ray diffraction: 0.3356 nm, specific surface area: 35 m ² / g), and containing acrylonitrile An artificial graphite / resin composite was obtained by kneading 30 parts by mass of a styrene-acrylonitrile copolymer (manufactured by Technopolymer Co., Ltd.) of about 30% by mass with a kneader while heating at 250 ° C. for 1 hour. The artificial graphite is an example of a carbon material and forms a core of artificial graphite / resin composite.

  The obtained artificial graphite / resin composite was crushed with a stamp mill, then calcined at 1000 ° C. for 2 hours in a nitrogen atmosphere, carbonized, then pulverized with a ball mill, and passed through a sieve with an opening of 1 mm. . Finally, the passing material of the sieve was pulverized with a jet mill to obtain a negative electrode active material having a D50 of 1.9 μm. Table 1 shows other physical properties of the obtained negative electrode active material.

(ii) Production of Negative Electrode Precursor A precursor layer having a length of 50 mm × width of 50 mm and a thickness of 40 μm was formed on a current collector made of a copper foil having a surface roughness Ra = 0.1 μm. The precursor layer is a layer containing the negative electrode active material obtained in (i) above, carboxymethyl cellulose, acetylene black (conductive agent) and a dispersant in a mass ratio of 88: 4: 5: 3.

  The precursor layer was formed by preparing a slurry containing the above components, applying the slurry onto a current collector, and drying the slurry. The negative electrode active material contained in the precursor layer is in a state before being doped with an alkali metal. The current collector and the precursor layer formed thereon are collectively referred to as a negative electrode precursor below.

(iii) Manufacture of Negative Electrode The negative electrode precursor obtained in (ii) above was used as one electrode, and lithium metal was used as a counter electrode, and electrolytic treatment was performed in a dope electrolyte. The electrolytic solution for dope contains 1.0 M LiPF ₆ and contains a mixed solvent of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate as an organic solvent. The volume ratio of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is 30:40:30. The electric current value in the electric field treatment was 10 C, and current was supplied until the occlusion rate of lithium reached 80% with respect to the capacity of the negative electrode active material.

As a result of the electric field treatment, a negative electrode including a current collector and a layer (negative electrode active material layer) containing a negative electrode active material doped with lithium formed thereon was obtained.
(iv) Production of Lithium Ion Capacitor The negative electrode obtained in (iii) above and a positive electrode using activated carbon as a positive electrode active material are opposed to each other through a separator, and a lithium ion capacitor laminate cell (hereinafter simply referred to as a laminate cell). Assembled).

Next, an electrolytic solution was injected into the laminate cell. The electrolytic solution contains 1.0 M LiPF ₆ and contains a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate as an organic solvent. The volume ratio of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is 30:40:30.

After injecting the electrolytic solution, it was sealed under reduced pressure to obtain a lithium ion capacitor.
(v) Evaluation of Lithium Ion Capacitor The amount of gas generated when the lithium ion capacitor obtained in (iv) above was kept charged in a constant temperature room at 70 ° C. was measured. The measurement results are shown in Table 1 above. The amount of gas was measured by measuring the volume change of the laminate cell before and after charging. The volume of the laminate cell was measured by the Archimedes method using water as an immersion liquid. Further, the DC internal resistance at −30 ° C. of the lithium ion capacitor obtained in (iv) was measured. The evaluation results are shown in Table 1 above. In addition, the evaluation result about the amount of gas and direct-current internal resistance was made into the relative value when the value in the comparative example 1 mentioned later is set to 100.

(Example 2)
In Example 1, a negative electrode was produced in the same manner as in Example 1 except that LiN (FSO ₂ ) ₂ was used instead of LiPF ₆ as the lithium salt contained in the doping electrolyte. Using the obtained negative electrode, a lithium ion capacitor was produced and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1 above.

(Example 3)
According to Example 4 described in JP 2013-258392 A, a negative electrode active material having a D50 of 5.2 μm was produced. Specifically, “carbon material A” was obtained by pulverizing commercially available artificial graphite with a ball mill. The macropore volume of “carbon material A” was 0.095 cc / g.

  After mixing 50 parts by mass of this “carbon material A” and 50 parts by mass of “pitch D” having a softening point of 90 ° C., the mixture was sufficiently kneaded with a kneader, and the kneaded product was calcined and carbonized at 1000 ° C. for 3 hours in a nitrogen atmosphere. Then, it was pulverized and classified with a ball mill to obtain a negative electrode active material made of a composite carbon material. In this negative electrode active material, “carbon material A” forms the core.

  A negative electrode was produced in the same manner as Example 1 using the obtained negative electrode active material. Using the obtained negative electrode, a lithium ion capacitor was produced and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1 above.

Example 4
In Example 3, a negative electrode was produced in the same manner as in Example 3 except that LiN (FSO ₂ ) ₂ was used instead of LiPF ₆ as the lithium salt contained in the doping electrolyte. Using the obtained negative electrode, a lithium ion capacitor was produced and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1 above.

(Comparative Example 1)
In Example 1, a lithium ion capacitor was manufactured and evaluated in the same manner as in Example 1 except that the step of doping lithium was not performed. The evaluation results are shown in Table 1 above.

(Comparative Example 2)
In Example 3, a lithium ion capacitor was manufactured and evaluated in the same manner as in Example 3 except that the step of doping lithium was not performed. The evaluation results are shown in Table 1.

Claims (7)

  A method of manufacturing an electrode constituting an electricity storage device, wherein an active material having a 50% volume cumulative diameter D50 of 10 μm or less is doped with an alkali metal in an electrolyte containing an alkali metal salt before assembling the electricity storage device. The manufacturing method of the electrode including the process to do.   The method for producing an electrode according to claim 1, wherein the active material is a carbon material. The manufacturing method of the electrode of Claim 1 or 2 whose specific surface area of the said active material is 5 m < ² > / g or more.   The manufacturing method of the electrode of any one of Claims 1-3 whose at least one part of the said alkali metal salt is an alkali metal salt containing the sulfonylimide anion which has a fluoro group.   The manufacturing method of the electrode of any one of Claims 1-4 whose at least one part of the said alkali metal salt is lithium salt.   The manufacturing method of the electrode of any one of Claims 1-5 whose said electrode is a negative electrode of an electrical storage device.   An electrical storage device provided with the negative electrode manufactured by the manufacturing method of the electrode of any one of Claims 1-5, a positive electrode, and electrolyte.