JP2016046287A - Nonaqueous electrolyte power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte power storage device which has a high energy density, and meets the requirement of high-speed charge and discharge characteristics.SOLUTION: A nonaqueous electrolyte power storage device comprises: a positive electrode including a positive electrode active material which allows an anion to go thereinto and to go out thereof; a negative electrode including a negative electrode active material; and a nonaqueous electrolytic solution including a nonaqueous solvent, an electrolyte salt including a halogen atom and a compound including a halogen atom, and having a part to which an anion can be bonded. A carbon active material used for the positive electrode active material is porous carbon of a three-dimensional network structure which is totally or partially crystallized and has meso pores communicating to each other and having a pore diameter of 2 nm or larger.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nonaqueous electrolyte storage element in which an anion is inserted into or removed from a positive electrode and a cation is inserted into or removed from the negative electrode.

  In recent years, with the downsizing and higher performance of portable devices, the characteristics of non-aqueous electrolyte storage elements with high energy density have improved and become widespread. Non-aqueous electrolyte storage elements with higher capacity and superior safety Development is also underway, and installation in electric vehicles has begun.

  Such a non-aqueous electrolyte storage element includes a positive electrode such as a lithium cobalt composite oxide, a carbon negative electrode, and a non-aqueous electrolyte obtained by dissolving a lithium salt in a non-aqueous solvent. Lithium ion secondary batteries that are charged / discharged are often used because lithium inside is desorbed and inserted into carbon of the negative electrode, and lithium inserted into the negative electrode is desorbed and returns to the composite oxide of the positive electrode during discharge. .

  On the other hand, when a power storage element is used in a hybrid vehicle or the like, it is essential to be able to output a large current instantaneously, and it is desirable that it can be charged with regenerative energy. Therefore, electric double layer capacitors that can be charged and discharged at high speed without requiring a chemical reaction are used. However, compared with the lithium ion storage element, the energy density is a few tenths, and a heavy storage element is required to secure a sufficient capacity. When the battery is loaded on an automobile, improvement in fuel efficiency is hindered.

  As an energy storage device having a high energy density and suitable for high-speed charge / discharge, a conductive polymer, a carbon material or the like is used as a positive electrode, a negative electrode such as carbon, and a non-aqueous electrolyte obtained by dissolving a lithium salt in a non-aqueous solvent The anion in the non-aqueous electrolyte is inserted into the positive electrode and the cation into the negative electrode during charging, and the anion and cation inserted into the positive electrode and the negative electrode are desorbed into the electrolyte during discharging. It is expected that a so-called dual intercalation type nonaqueous electrolyte storage element that is charged and discharged by the above will be put to practical use.

When LiPF6 is used as the lithium salt, as shown in the following reaction formula, charging is performed by inserting PF ₆ ⁻ into the positive electrode from the nonaqueous electrolyte and inserting Li ⁺ into the negative electrode. PF ₆ ⁻ and Li ⁺ are desorbed from the negative electrode to the non-aqueous electrolyte, thereby discharging.

As an active material that occludes / releases anions, a case where a graphite material is used as in Patent Documents 1 to 3 is known.
When graphite is used as the positive electrode active material, a high capacity is obtained by setting the charge end voltage to 5.3 to 5.6 V with respect to the lithium reference electrode as described in Patent Document 1 (Patent No. 4392169). It is known that a secondary battery can be obtained. Patent Document 2 (Patent No. 4314087) describes that a secondary battery having excellent cycle characteristics can be obtained by using borated graphite, and Patent Document 3 (Patent No. 4569126) discloses high-speed discharge. particularly negative for obtaining the properties, metallic lithium, or BET specific surface area of at 0.5m ² /g~25.0m ² / g, it is disclosed that the use of carbonaceous material having a particle size 1μm~100μm .
However, according to the study by the present inventors, when graphite is used for the positive electrode, the capacity cannot be sufficiently increased under high voltage and rapid charge / discharge conditions (1C or more), and the capacity is reduced in several cycles. .

WO 2008-123606 of Patent Document 4 discloses a porous carbon material made from a plant-derived material which is treated with an acid or an alkali after carbonizing the plant-derived material at 800 ° C. to 1400 ° C. Although it is described that a porous carbon material for an electrode can be obtained by using a plant-derived material having a silicon content of 10% by weight or more as a raw material, this technique relates to a fuel cell. Further, the porous carbon material obtained is not related to the secondary battery, and the obtained porous carbon material is a poorly porous material having a specific surface area value of 10 m @ 2 / g and a pore volume of 0.1 cm @ 3 / g by the nitrogen BET method. is there.
In WO2011-0665484 of Patent Document 5, a battery having an electric double layer capacitor using a carbon porous material having a specific surface area of 200 to 3000 m ² / g as an electrode is described. The melamine monomer, which relates to a fuel cell based on the recognition that a nitrogen-containing carbon material is more suitable as an electrode material for an EDLC of a fuel cell, is not related to a secondary battery, Since it sublimates by heat treatment, it cannot be directly used as a raw material for the nitrogen-containing porous carbon material, and the main purpose is to overcome the difficulty in easily producing the nitrogen-containing porous carbon material. Also, a carbon porous material that is at least partially crystallized is not used.

  An object of the present invention is to provide a non-aqueous electrolyte storage element that has a high energy density and satisfies high-speed charge / discharge characteristics in view of the above-described prior art.

Means for solving the problems are as follows. That is,
The nonaqueous electrolyte storage element of the present invention is solved by the “nonaqueous electrolyte storage element” described in (1) below.
(1) “A site capable of binding a positive electrode containing a positive electrode active material capable of inserting or removing anions, a negative electrode containing a negative electrode active material, a nonaqueous solvent, an electrolyte salt containing a halogen atom, and an anion containing a halogen atom A non-aqueous electrolyte storage element having a non-aqueous electrolyte containing a compound having a carbon active material used for the positive electrode active material having a mesopore having a pore diameter of 2 nm or more in a three-dimensional network structure. Non-aqueous electrolyte storage element characterized by being porous carbon crystallized or partially crystallized. "

  As is clear from the following detailed and specific description, according to the present invention, (1) it is possible to provide a storage element having a capacity similar to graphite and capable of increasing the discharge rate, and (2) an anion to the positive electrode Insertion can be utilized, a high-capacity storage element can be provided, and (3) a high concentration electrolyte can be used, and the energy density of the cell can be increased.

Discharges when the discharge capacity, discharge current value, and charge current value at the reference current value (I) in Examples and Comparative Examples are increased ((II), (IV), (VI), (VIII)) It is the figure which showed what plotted the value of the capacity | capacitance.

  Hereinafter, the present invention will be described in detail. The present invention relates to a “nonaqueous electrolyte storage element” having the configuration described in (1) above. As will be understood from the following detailed description, it also includes the “nonaqueous electrolyte storage element” of the embodiments described in the following (2) to (3), and these are also described in detail. To do.

(2) The porous carbon has a BET specific surface area value of 500 to 2000 m ² / g, a mesopore diameter value of 2 to 200 nm, and a micropore volume of 1.00 mL / g or less. Water electrolyte storage element.
(3) The nonaqueous electrolyte storage element according to (1), wherein the porous carbon has a carbon crystal structure.

[Configuration of nonaqueous electrolyte storage element]
1. The positive electrode is not particularly limited as long as it contains a positive electrode storage material (positive electrode active material or the like), and can be appropriately selected according to the purpose. For example, a positive electrode material having a positive electrode active material on a positive electrode current collector And the like.
There is no restriction | limiting in particular as a shape of the said positive electrode, According to the objective, it can select suitably, For example, flat form etc. are mentioned.

1-1. Positive electrode material The positive electrode material is not particularly limited and may be appropriately selected depending on the purpose.For example, the positive electrode material includes at least a positive electrode active material, and further includes a conductive additive, a binder, a thickener, and the like as necessary. Comprising.

(1) Positive electrode active material As the positive electrode active material, crystalline or partially porous crystallized carbon having pores (mesopores) having a pore diameter of 2 nm or more connected in a three-dimensional network structure is used. The “positive electrode active material having a mesopore having a pore size of 2 nm or more in communication with a three-dimensional network structure” has positive and negative electrolyte ions paired on both sides of the surface where the mesopore (cavity portion) and the carbon material portion are in contact with each other. Since it is a capacitor in which a charge double layer is formed by the presence, the movement of the electrolyte ions present in a pair sequentially undergoes a chemical reaction with the polar active material, and then the generated electrolyte ions move to the next. It is understood that the power supply capability depends on the surface area of the mesopores where positive and negative electrolyte ion pairs exist, as well as the volume of the cavity.
Looking at the crystallinity of the porous carbon, the time constant of the capacitor (slow response at the time of charging / discharging) depends not only on the capacitance of the non-aqueous electrolyte but also on the resistance value of the carbon material part that makes ohmic contact with it. It depends. Furthermore, since both electrolyte ions are accompanied by a chemical reaction that repeats bond separation with the polar active material for each, it is possible to consider that it is preferable that the electrolyte ions also have strength to withstand the deterioration.
Note that it is not necessary that all the carbonaceous portions have a crystal structure, and an amorphous portion may exist in part.

In porous carbon, mesopores are essential, but micropores are not essential. Therefore, although the micropores may or may not exist, the organic substance as the carbon material forming source usually carbonizes by releasing volatile substances during carbonization, and thus usually the micropores as emission traces. It is difficult to have no micropores. In contrast, mesopores are usually formed intentionally. For example, as known, an acid (alkali) -soluble metal, metal oxide, metal salt, metal-containing organic material and a carbon material or an organic material as a raw material are molded together, and then an acid ( In many cases, the traces of the muscle parts dissolved by alkali) become mesopores.
Here, in this specification, those having a pore diameter of less than 2 nm are referred to as micropores, and those having a pore diameter of 2 to 50 nm are referred to as mesopores. Since the size of the electrolyte ions is 0.5 nm to 2 nm, it is difficult to say that the micropores contribute much to the movement of ions. Therefore, mesopores are important for the smooth movement of ions. Incidentally, the pore size of activated carbon, which is the same carbonaceous material, is said to be about 1 nm on average, and in the case of activated carbon, it is regarded as one of all adsorption accompanied by exotherm (decrease in enthalpy) without exception.
The mesopores of the above size preferably have a three-dimensional network structure.
If the hole has a three-dimensional network structure, ions move smoothly.

The specific surface area is desirably 500 m ² / g or more.
When the specific surface area is less than 500 m ² / g, the amount of pores formed is insufficient, ions are not sufficiently inserted, and the capacity cannot be increased.
On the other hand, if the specific surface area is desirably 2000 m ² / g or less, if the specific surface area exceeds 2000 m ² / g, the formation of mesopores is not sufficient, and the insertion of ions is hindered, so that the capacity cannot be increased.
The mesopores are open pores, and it is necessary that the pore portions are continuous.
If it is the said structure, ion will move smoothly.
The volume of the micropores is desirably 1.00 ml / g or less.
If the micropore volume exceeds 1.00 ml / g, the insertion and desorption of ions may be inhibited, and the capacity may be reduced.

(2) Binder and thickener The binder and the thickener are not particularly limited as long as they are materials that are stable with respect to the solvent and electrolyte used during electrode production and the applied potential, depending on the purpose. For example, fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), isoprene rubber Acrylate latex, carboxymethyl cellulose (CMC), methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyacrylic acid, polyvinyl alcohol, alginic acid, oxidized starch, phosphate starch, casein, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), acrylate latex, and carboxymethyl cellulose (CMC) are preferable.

(3) Conductive aid Examples of the conductive aid include metal materials such as copper and aluminum, and carbonaceous materials such as carbon black, acetylene black, and carbon nanotube. These may be used individually by 1 type and may use 2 or more types together.

1-2. Positive electrode current collector The material, shape, size, and structure of the positive electrode current collector are not particularly limited and may be appropriately selected depending on the intended purpose.
The material of the positive electrode current collector is formed of a conductive material and is not particularly limited as long as it is stable with respect to the applied potential, and can be appropriately selected according to the purpose. For example, stainless steel Nickel, aluminum, titanium, tantalum, and the like. Among these, stainless steel and aluminum are particularly preferable.
There is no restriction | limiting in particular as a shape of the said positive electrode electrical power collector, According to the objective, it can select suitably.
The size of the positive electrode current collector is not particularly limited as long as it is a size that can be used for a non-aqueous electrolyte storage element, and can be appropriately selected according to the purpose.

1-3. Method for Producing Positive Electrode The positive electrode comprises a positive electrode material formed into a slurry by adding the binder, the thickener, the conductive agent, a solvent, and the like to the positive electrode active material as necessary on the positive electrode current collector. It can be manufactured by applying and drying. There is no restriction | limiting in particular as said solvent, According to the objective, it can select suitably, For example, an aqueous solvent, an organic solvent, etc. are mentioned. Examples of the aqueous solvent include water, alcohol, and the like. Examples of the organic solvent include N-methyl-2-pyrrolidone (NMP), toluene, and the like.
In addition, the positive electrode active material can be roll-formed as it is to form a sheet electrode, or a pellet electrode by compression molding.

2. The negative electrode is not particularly limited as long as it contains a negative electrode active material, and can be appropriately selected according to the purpose. For example, a negative electrode including a negative electrode material having a negative electrode active material on a negative electrode current collector, etc. Is mentioned.
There is no restriction | limiting in particular as a shape of the said negative electrode, According to the objective, it can select suitably, For example, flat form etc. are mentioned.

2-1. Negative electrode material The negative electrode material includes at least a negative electrode storage material (negative electrode active material and the like), and further includes a conductive additive, a binder, a thickener, and the like as necessary.

(1) Negative electrode active material The negative electrode active material is not particularly limited as long as it is a substance that occludes and desorbs lithium ions in at least a non-aqueous solvent system. Specifically, carbonaceous material, antimony tin oxide, monoxide Metal oxides that can occlude and release lithium such as silicon, metals or metal alloys that can be alloyed with lithium such as aluminum, tin, silicon, and zinc, metals that can be alloyed with lithium, alloys containing the metal, and lithium And composite metal compounds of lithium metal nitride such as cobalt lithium nitride. These may be used individually by 1 type and may use 2 or more types together. Among these, carbonaceous materials are particularly preferable from the viewpoint of safety and cost.
Examples of the carbonaceous material include graphite (graphite) such as coke, artificial graphite and natural graphite, and organic pyrolysis products under various pyrolysis conditions. Among these, artificial graphite and natural graphite are particularly preferable.

(2) Binder and thickener The binder and thickener are not particularly limited as long as they are materials that are stable with respect to the solvent and electrolyte used during electrode production and the applied potential. For example, fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), isoprene rubber, acrylate Examples thereof include system latex, carboxymethylcellulose (CMC), methylcellulose, hydroxymethylcellulose, ethylcellulose, polyacrylic acid, polyvinyl alcohol, alginic acid, oxidized starch, phosphate starch, and casein. These may be used individually by 1 type and may use 2 or more types together. Among these, fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) are preferable.

(3) Conductive aid Examples of the conductive aid include metal materials such as copper and aluminum, and carbonaceous materials such as carbon black, acetylene black, and carbon nanotube. These may be used individually by 1 type and may use 2 or more types together.

2-2. Negative electrode current collector The material, shape, size, and structure of the negative electrode current collector are not particularly limited and may be appropriately selected depending on the intended purpose.
The material of the negative electrode current collector is formed of a conductive material and is not particularly limited as long as it is stable with respect to the applied potential, and can be appropriately selected according to the purpose. Steel, nickel, aluminum, copper, etc. are mentioned. Among these, stainless steel, copper, and aluminum are particularly preferable.
There is no restriction | limiting in particular as a shape of the said electrical power collector, According to the objective, it can select suitably.
The size of the current collector is not particularly limited as long as it is a size that can be used for a nonaqueous electrolyte storage element, and can be appropriately selected according to the purpose.

2-3. Method for Producing Negative Electrode The negative electrode is coated on the negative electrode current collector with a negative electrode material made into a slurry by adding the binder and thickener, the conductive agent, a solvent, etc. to the negative electrode active material as necessary. And can be produced by drying. As the solvent, the same solvent as that for the positive electrode can be used.
In addition, the negative electrode active material added with the binder, the thickener, the conductive agent and the like is roll-formed as it is to form a sheet electrode, or a pellet electrode by compression molding, or a method such as vapor deposition, sputtering, plating, etc. A thin film of the negative electrode active material may be formed on the negative electrode current collector.

3. Nonaqueous Electrolytic Solution The nonaqueous electrolytic solution is an electrolytic solution obtained by dissolving an electrolyte salt in a nonaqueous solvent.

3-1. Nonaqueous solvent The nonaqueous solvent is not particularly limited and may be appropriately selected depending on the intended purpose, but an aprotic organic solvent is preferred.
As the aprotic organic solvent, carbonate-based organic solvents such as chain carbonates and cyclic carbonates are used, and low viscosity solvents are preferred. Among these, a chain carbonate is preferable from the viewpoint that the electrolyte salt has a high dissolving power.
Examples of the chain carbonate include dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC). Among these, dimethyl carbonate (DMC) is preferable.
The content of the DMC is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 70% by mass or more and more preferably 83% by mass or more with respect to the non-aqueous solvent. If the content of the DMC is less than 70% by mass, the amount of the cyclic substance having a high dielectric constant increases when the remaining solvent is a cyclic substance (cyclic carbonate, cyclic ester, etc.) having a high dielectric constant. When a non-aqueous electrolyte solution having a high concentration of 3M or more is produced, the viscosity becomes too high, which may cause problems in terms of penetration of the non-aqueous electrolyte solution into the electrode and ion diffusion.

Examples of the cyclic carbonate include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), vinylene carbonate (VC), and the like.
When a mixed solvent combining ethylene carbonate (EC) as the cyclic carbonate and dimethyl carbonate (DMC) as the chain carbonate is used, the mixing ratio of ethylene carbonate (EC) and dimethyl carbonate (DMC) is particularly Although there is no restriction | limiting and it can select suitably according to the objective, Mass ratio (EC: DMC) is preferably 3:10 to 1:99, and more preferably 3:10 to 1:20.

In addition, as said non-aqueous solvent, ester type organic solvents, such as cyclic ester and chain ester, ether type organic solvents, such as cyclic ether and chain ether, etc. can be used as needed.
Examples of the cyclic ester include γ-butyrolactone (γBL), 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone.
Examples of the chain ester include propionic acid alkyl ester, malonic acid dialkyl ester, acetic acid alkyl ester (methyl acetate (MA), ethyl acetate, etc.), formic acid alkyl ester (methyl formate (MF), ethyl formate, etc.), etc. Is mentioned.
Examples of the cyclic ether include tetrahydrofuran, alkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, 1,4-dioxolane, and the like.
Examples of the chain ether include 1,2-dimethoxyethane (DME), diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, and tetraethylene glycol dialkyl ether.

3-2. Electrolyte salt A lithium salt is used as the electrolyte salt. There is no particular limitation as long as it dissolves in a non-aqueous solvent and exhibits high ionic conductivity. For example, lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium chloride (LiCl), borofluorination Lithium (LiBF4), lithium arsenic hexafluoride (LiAsF6), lithium trifluorometasulfonate (LiCF3SO3), lithium bistrifluoromethylsulfonylimide (LiN (C2F5SO2) 2), lithium bisferfluoroethylsulfonylimide (LiN (CF2F5SO2) 2), and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, LiPF6 is particularly preferable from the viewpoint of the amount of occlusion of anions in the carbon electrode.
There is no restriction | limiting in particular as a density | concentration of the said electrolyte salt, Although it can select suitably according to the objective, 0.5 mol / L-6 mol / L are preferable in the said nonaqueous solvent, and battery capacity and output are compatible. From this point, 2 mol / L to 4 mol / L is more preferable.

4). Separator The separator is provided between the positive electrode and the negative electrode in order to prevent a short circuit between the positive electrode and the negative electrode.
There is no restriction | limiting in particular as a material of the said separator, a shape, a magnitude | size, and a structure, According to the objective, it can select suitably.
Examples of the material of the separator include paper such as kraft paper, vinylon mixed paper, synthetic pulp mixed paper, cellophane, polyethylene graft membrane, polyolefin nonwoven fabric such as polypropylene melt blown nonwoven fabric, polyamide nonwoven fabric, glass fiber nonwoven fabric, and micropore membrane. Can be mentioned.
Among these, those having a porosity of 50% or more are preferable from the viewpoint of holding the electrolytic solution. As the shape, a non-woven fabric system is preferable because it has a higher porosity than a thin film type having micropores. As thickness, 20 micrometers or more are preferable from a viewpoint of short circuit prevention and electrolyte solution holding | maintenance.
There is no restriction | limiting in particular as long as the magnitude | size of the said separator is a magnitude | size which can be used for a non-aqueous electrolyte electrical storage element, It can select suitably according to the objective.
The separator may have a single layer structure or a laminated structure.

5). Manufacturing method of non-aqueous electrolyte storage element The non-aqueous electrolyte storage element of the present invention assembles the positive electrode, the negative electrode, and the non-aqueous electrolyte and a separator used as necessary into an appropriate shape. Manufactured by. Furthermore, other constituent members such as a battery outer can can be used as necessary. There is no restriction | limiting in particular as a method of assembling the said non-aqueous electrolyte electrical storage element, It can select suitably from the methods employ | adopted normally.
There is no restriction | limiting in particular about the shape of the non-aqueous-electrolyte electrical storage element of this invention, According to the use, it can select suitably from the various shapes generally employ | adopted. Examples of the shape include a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, and a coin type in which a pellet electrode and a separator are stacked.

6). Uses The use of the nonaqueous electrolyte storage element of the present invention is not particularly limited and can be used for various uses. For example, notebook computers, pen input personal computers, mobile personal computers, electronic book players, mobile phones, mobile faxes, Portable copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, motor, lighting equipment, toy, Game devices, watches, strobes, cameras, etc.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Example 1]
Porous carbon A (Knobel: Toyo Tanso) as the positive electrode active material, acetylene black (Denka black powder: Electrochemical Industry) as the conductive aid, acrylate latex (TRD202A: JSR) as the binder, and carboxymethyl cellulose (Thickener) Daicel 2200: Daicel Chemical Industries) were mixed so that the weight ratio of the solids was 100: 7.5: 3.0: 3.8, and water was added to adjust the slurry to an appropriate viscosity. The aluminum foil having a thickness of 20 μm was coated on one side using a doctor blade. The average basis weight after drying was 5.8 mg / cm ² . This was punched out to φ16 mm to obtain a positive electrode.
As the separator, two pieces of glass filter paper (GA100: ADVANTEC) punched to φ16 mm were used, and a φ16 mm lithium metal foil was used for the negative electrode.
As the electrolytic solution, a DMC solution of 2 mol / L LiPF6 was used.

<Production and measurement of battery>
The positive electrode and the separator were vacuum dried at 150 ° C. for 4 hours, and then a 2032 type coin cell was assembled in a dry argon glove box.
The produced electrical storage element was hold | maintained in a 25 degreeC thermostat, and the charging / discharging test was implemented on conditions like the following (I)-(VIII). Reference current value is 0.5mA (1C), (II) and (VI) are 5 times (5C) and 10 times (10C) the reference current value for discharging only, and (IV) and (VIII) are charging Only 5 times (5C) and 10 times (10C) of the reference current value were used. In all cases, charging was a constant current with a cut-off voltage of 5.2 V, discharge was a cut-off voltage of 3.0 V, and a 5-minute pause was inserted between charging and discharging and discharging and charging.
(I) Charging 0.5mA Discharging 0.5mA 10 times
(II) Charging 0.5mA Discharging 2.5mA 5 times
(III) Charging 0.5mA Discharging 0.5mA 2 times
(IV) Charging 2.5mA Discharging 0.5mA 5 times
(V) Charging 0.5mA Discharging 0.5mA 2 times
(VI) Charging 0.5mA Discharging 5.0mA 5 times
(VII) Charging 0.5mA Discharging 0.5mA 2 times
(VIII) Charging 5.0mA Discharging 0.5mA 5 times

[Example 2]
Porous carbon B (Knobel: Toyo Tanso) having lower crystallinity than Example 1 as a positive electrode active material, acetylene black (Denka black powder: Electrochemical Industry) as a conductive additive, and acrylate latex (TRD202A: JSR) as a binder ), Carboxymethylcellulose (Daicel 2200: Daicel Chemical Industries) as a thickener is mixed so that the weight ratio of solids is 100: 7.5: 2.9: 14.3, respectively, and water is added. The slurry adjusted to an appropriate viscosity was applied to one side of a 20 μm thick aluminum foil using a doctor blade. The average basis weight after drying was 1.2 mg / cm ² . This was punched out to φ16 mm to obtain a positive electrode.
As the separator, two pieces of glass filter paper (GA100: ADVANTEC) punched to φ16 mm were used, and a φ16 mm lithium metal foil was used for the negative electrode.
As the electrolytic solution, a DMC solution of 2 mol / L LiPF6 was used.

<Production and measurement of battery>
The positive electrode and the separator were vacuum dried at 150 ° C. for 4 hours, and then a 2032 type coin cell was assembled in a dry argon glove box.
The produced electrical storage element was hold | maintained in a 25 degreeC thermostat, and the charging / discharging test was implemented on conditions like the following (I)-(VIII). The reference current value is 0.3 mA, (II) and (VI) are 5 times (5C) and 10 times (10C) the reference current value for discharge only, and (IV) and (VIII) are the reference current for charge only The value was 5 times (5C) or 10 times (10C). In all cases, charging was a constant current with a cut-off voltage of 5.2 V, discharge was a cut-off voltage of 3.0 V, and a 5-minute pause was inserted between charging and discharging and discharging and charging.
(I) Charge 0.3mA Discharge 0.3mA 10 times
(II) Charge 0.3mA Discharge 1.5mA 5 times
(III) Charge 0.3mA Discharge 0.3mA 2 times
(IV) Charging 1.5mA Discharging 0.3mA 5 times
(V) Charge 0.3mA Discharge 0.3mA 2 times
(VI) Charge 0.3mA Discharge 3.0mA 5 times
(VII) Charge 0.3mA Discharge 0.3mA 2 times
(VIII) Charging 3.0mA Discharging 0.3mA 5 times

[Comparative Example 1]
As the positive electrode active material, natural graphite (special CP: manufactured by Nippon Graphite Industry) was used. Otherwise, electrodes and batteries were prepared in the same manner as in Example 1. The average basis weight after drying was 10.5 mg / cm ² .
The reference current value was set to 2.0 mA, and otherwise, evaluation was performed in the same manner as in Examples 1 and 2.

[Comparative Example 2]
As the positive electrode active material, activated carbon (Bellfine AP: manufactured by AT Electrode) was used. Otherwise, electrodes and batteries were prepared in the same manner as in Example 1. The average weight per unit area after drying was 8.9 mg / cm ² .
The reference current value was set to 2.0 mA, and otherwise, evaluation was performed in the same manner as in Examples 1 and 2.

[Comparative Example 3]
As the positive electrode active material, mesoporous carbon (carbon mesoporous: manufactured by Sigma Aldrich) is used, acetylene black (Denka black powder: Denki Kagaku Kogyo) as a conductive assistant, acrylate latex (TRD202A: JSR) as a binder, thickener Carboxymethyl cellulose (Daicel 2200: Daicel Chemical Industries) is mixed so that the weight ratio of solids is 100: 7.5: 5.8: 17.8, respectively, and adjusted to an appropriate viscosity by adding water. The slurry was applied to one side of a 20 μm thick aluminum foil using a doctor blade. The average basis weight after drying was 1.3 mg / cm ² .
Otherwise, electrodes and batteries were produced in the same manner as in Examples 1 and 2.
The evaluation was performed in the same manner as in Examples 1 and 2 except that the reference current value was 0.075 mA.

[Example 3]
As the positive electrode active material, porous carbon C (Knobel: Toyo Tanso) having the same degree of crystallinity as in Example 2 and a pore diameter of 2 nm was used. Otherwise, an electrode and a battery were prepared and evaluated in the same manner as in Example 1. Went.

[Example 4]
As the positive electrode active material, porous carbon D (Cnobel: Toyo Tanso) having the same degree of crystallinity as in Example 2 and a pore diameter of 10 nm was used. Went.

  Table 1 shows the tenth discharge capacity at each reference current value (I) and the maintenance ratio of the fifth discharge capacity (II), (IV), (VI), and (VIII). The physical property values of the positive electrode active material are also shown. D50 is the laser diffraction method, the pore diameter is calculated by the BJH method of the gas adsorption curve, and the specific surface area is a value measured by the gas adsorption method. The discharge capacity is described as a specific capacity per weight of the positive electrode active material.

実施例１では、基準電流値における容量も比較的高く、放電電流値、充電電流値を高くしたときの放電容量維持率も比較的高い。実施例２では、基準電流値における容量も実施例１よりも高く、放電電流値、充電電流値を高くしたときの放電容量維持率も高い。これに対し、比較例１は基準電流値における容量は実施例２よりも低く（実施例１と同等）、放電電流値を高くしたときの放電容量維持率は比較的高いものの、充電電流値を高くした場合の放電容量維持率低下が大きい。比較例２は基準電流値における容量も低く、放電電流値、充電電流値を高くした場合の放電容量維持率低下が非常に大きい。比較例３は放電電流値、充電電流値を上げた場合の放電容量維持率は良好であるが、基準電流値での容量が小さく、高エネルギー密度の蓄電素子が実現できない。

また、図1に各実施例、比較例に於ける（I）の基準電流値での放電容量と放電電流値、充電電流値を高くした場合（(II)、(IV)、(VI)、(VIII)）の放電容量の値をプロットしたものを示した。実施例１に於いては放電電流値、充電電流値を高くした場合（(II)、(IV)、(VI)、(VIII)）の容量は比較例１（天然黒鉛）と同等の容量が得られるこことが分かった。実施例２に於いて放電電流値、充電電流値を高くした場合（(II)、(IV)、(VI)、(VIII)）の容量維持率はやや低いものの、実施例１の結晶性の高いものよりも高い容量が得られることが分かった。

また、結晶性が同程度である実施例２〜４のように、細孔径を変化させても高い容量が得られることが分かった。実施例４に於いては他のどの実施例、比較例よりも高い容量が得られることが分かった。この結果から、正極へのアニオン挿入を利用した、充放電レートの速い高容量の蓄電素子を提供できる。

In Example 1, the capacity at the reference current value is also relatively high, and the discharge capacity maintenance rate when the discharge current value and the charge current value are increased is also relatively high. In Example 2, the capacity at the reference current value is also higher than that in Example 1, and the discharge capacity maintenance rate when the discharge current value and the charge current value are increased is also high. On the other hand, in Comparative Example 1, the capacity at the reference current value is lower than that in Example 2 (equivalent to Example 1), and the discharge capacity retention rate when the discharge current value is increased is relatively high. The decrease in the discharge capacity maintenance rate when it is increased is large. In Comparative Example 2, the capacity at the reference current value is also low, and the decrease in the discharge capacity maintenance rate when the discharge current value and the charge current value are increased is very large. In Comparative Example 3, the discharge capacity retention rate is good when the discharge current value and the charge current value are increased, but the capacity at the reference current value is small, and a high energy density storage element cannot be realized.

In addition, when the discharge capacity and the discharge current value at the reference current value (I) in each example and comparative example in FIG. 1 are increased ((II), (IV), (VI), A plot of the discharge capacity value of (VIII)) is shown. In Example 1, when the discharge current value and the charge current value are increased ((II), (IV), (VI), (VIII)), the capacity is equivalent to that of Comparative Example 1 (natural graphite). I found out that I could get it. When the discharge current value and the charge current value are increased in Example 2 ((II), (IV), (VI), (VIII)), although the capacity retention rate is slightly low, the crystallinity of Example 1 It has been found that higher capacities can be obtained than higher ones.

Moreover, it turned out that a high capacity | capacitance is obtained even if it changes a pore diameter like Examples 2-4 whose crystallinity is comparable. In Example 4, it turned out that a capacity | capacitance higher than any other Examples and a comparative example is obtained. From this result, it is possible to provide a high-capacity energy storage device that uses anion insertion into the positive electrode and has a fast charge / discharge rate.

Japanese Patent No. 4392169 Japanese Patent No. 4314087 Japanese Patent No. 4569126 WO2008-123606 WO2011-066544

Claims (3)

A positive electrode containing a positive electrode active material capable of inserting or removing anions, a negative electrode containing a negative electrode active material, a non-aqueous solvent, an electrolyte salt containing a halogen atom, and a compound having a site capable of binding an anion containing a halogen atom A non-aqueous electrolyte storage element having a non-aqueous electrolyte solution, wherein the carbon active material used for the positive electrode active material has a mesopore having a pore diameter of 2 nm or more in a three-dimensional network structure and is crystalline or A nonaqueous electrolyte storage element, characterized in that a part thereof is crystallized porous carbon.
^2. The non-aqueous electrolyte according to claim 1, wherein the porous carbon has a BET specific surface area value of 500 to 2000 m ² / g, a mesopore diameter value of 2 to 200 nm, and a micropore volume of 1.00 mL / g or less. Power storage element.
  The nonaqueous electrolyte storage element according to claim 1, wherein the porous carbon has a carbon crystal structure.

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