JP6786334B2 - Positive electrode precursor - Google Patents

Description

The present invention relates to a positive electrode precursor.

In recent years, from the viewpoint of effective use of energy aiming at conservation of the global environment and resource saving, power smoothing system or midnight power storage system for wind power generation, distributed power storage system for home use based on solar power generation technology, power storage for electric vehicles Systems and the like are attracting attention.

The first requirement for batteries used in these power storage systems is high energy density. Lithium-ion batteries are being energetically developed as promising candidates for high-energy density batteries that can meet such demands.

The second requirement is that the output characteristics are high. For example, in a combination of a high-efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle), high output discharge characteristics in the power storage system are required during acceleration. There is.

Currently, electric double layer capacitors, nickel-metal hydride batteries, and the like are being developed as high-power power storage devices.

Among the electric double layer capacitors, those using activated carbon for the electrodes have an output characteristic of about 0.5 to 1 kW / L. This electric double layer capacitor has high durability (cycle characteristics and high temperature storage characteristics), and has been considered to be the most suitable device in the field where high output is required. However, its energy density is only about 1 to 5 Wh / L. Therefore, it is necessary to further improve the energy density.

On the other hand, the nickel-metal hydride battery currently used in hybrid electric vehicles has a high output equivalent to that of an electric double layer capacitor and an energy density of about 160 Wh / L. However, research is being vigorously pursued to further increase its energy density and output and to improve its durability.

In addition, research is underway to increase the output of lithium-ion batteries. For example, a lithium ion battery has been developed in which a high output exceeding 3 kW / L can be obtained at a discharge depth (a value indicating what percentage of the discharge capacity of the power storage element is discharged) of 50%. However, its energy density is 100 Wh / L or less, and it is designed to intentionally suppress the high energy density, which is the greatest feature of lithium-ion batteries. Its durability (cycle characteristics and high temperature storage characteristics) is inferior to that of electric double layer capacitors. Therefore, in order to have practical durability, it is used in a range where the discharge depth is narrower than the range of 0 to 100%. Since the capacity that can be actually used becomes smaller, research for further improving the durability of lithium-ion batteries is being vigorously pursued.

As described above, there is a strong demand for practical application of a power storage element having high energy density, high output characteristics, and durability. However, each of the existing power storage elements described above has advantages and disadvantages. Therefore, a new power storage element that satisfies these technical requirements is required. As a promising candidate, a power storage element called a lithium ion capacitor has attracted attention and is being actively developed.

The energy of the capacitor is represented by 1/2 · C · V ² (in the equation, C is the capacitance and V is the voltage).

A lithium ion capacitor is a type of power storage element (non-aqueous hybrid capacitor) that uses a non-aqueous electrolyte solution containing a lithium salt, and at a positive electrode of about 3 V or more, adsorption and desorption of anions similar to those of an electric double layer capacitor. It is a power storage element that charges and discharges at the negative electrode by a Faraday reaction by storing and releasing lithium ions, which is similar to that of a lithium ion battery.

To summarize the above-mentioned electrode materials and their characteristics, high output and high durability are achieved when a material such as activated carbon is used for the electrodes and charging / discharging is performed by adsorption and desorption (non-Faraday reaction) of ions on the surface of activated carbon. However, the energy density becomes low (for example, it is multiplied by 1). When an oxide or carbon material is used for the electrode and charging / discharging is performed by a Faraday reaction, the energy density becomes high (for example, 10 times that of a non-Faraday reaction using activated carbon), but there are problems in durability and output characteristics. There is.

As a combination of these electrode materials, the electric double layer capacitor is characterized by using activated carbon (energy density 1 times) for the positive electrode and the negative electrode and charging / discharging both the positive electrode and the negative electrode by a non-Faraday reaction, and has high output and high durability. However, it is characterized by low energy density (1x positive electrode x 1x negative electrode = 1).

The lithium ion secondary battery is characterized by using a lithium transition metal oxide (energy density 10 times) for the positive electrode and a carbon material (energy density 10 times) for the negative electrode, and charging and discharging both the positive electrode and the negative electrode by a Faraday reaction. Although the energy density (positive electrode 10 times x negative electrode 10 times = 100), there are problems in output characteristics and durability. In order to satisfy the high durability required for hybrid electric vehicles and the like, the discharge depth must be limited, and a lithium ion secondary battery can use only 10 to 50% of its energy.

Lithium-ion capacitors use activated carbon (1x energy density) for the positive electrode and carbon material (10x energy density) for the negative electrode, and are characterized by performing charging and discharging by a non-Faraday reaction at the positive electrode and a Faraday reaction at the negative electrode. It is a new asymmetric capacitor that combines the characteristics of a multi-layer capacitor and a lithium-ion secondary battery. Lithium-ion capacitors have high energy density (1x positive electrode x 10x negative electrode = 10) while having high output and high durability, and there is no need to limit the discharge depth as in lithium-ion secondary batteries. Is a feature.

Various studies have been conducted on the positive electrodes of the power storage elements (particularly lithium ion secondary batteries) described above.

For example, Patent Document 1 proposes a lithium ion secondary battery that uses a positive electrode containing lithium carbonate in the positive electrode and has a current cutoff mechanism that operates in response to an increase in battery internal pressure. Patent Document 2 proposes a lithium ion secondary battery in which a lithium composite oxide such as lithium manganic acid is used as a positive electrode and lithium carbonate is contained in the positive electrode to suppress elution of manganese. Patent Document 3 proposes a method of oxidizing various lithium compounds as oxides at a positive electrode to recover the capacity of a deteriorated power storage element. Patent Document 4 proposes a method in which a carbonate, a hydroxide, or a silicate is contained in an activated carbon positive electrode as an antacid.

Japanese Unexamined Patent Publication No. 7-328278 Japanese Unexamined Patent Publication No. 2001-167767 Japanese Unexamined Patent Publication No. 2012-174437 Japanese Unexamined Patent Publication No. 2006-261516

However, in the methods described in Patent Documents 1 to 4, the predoping of the negative electrode in the non-aqueous hybrid capacitor is not considered at all, and the efficiency of the predoping and the high energy density and low resistance of the non-aqueous hybrid capacitor are discussed. There was room for further improvement.

One of the problems to be solved by the present invention is to provide a positive electrode precursor for a non-aqueous hybrid capacitor that can predope the negative electrode in a short time and has high energy density and high input / output.

The present inventor has diligently studied and repeated experiments in order to solve the above problems.
As a result, in the positive electrode precursor containing an alkali metal compound other than the positive electrode active material, the positive electrode precursor is a non-aqueous hybrid by controlling the weight ratio of the alkali metal compound and the element mapping on the surface of the positive electrode precursor to a specific state. It has been found that it becomes possible to promote the decomposition of alkali metal compounds when incorporated for a capacitor, the negative electrode can be pre-doped in a short time, and high energy density and high input / output can be obtained.
That is, the present invention is as follows.
[1]
It has an alkali metal compound other than the positive electrode active material, a positive electrode current collector, and a positive electrode active material layer on one side or both sides of the positive electrode current collector, and the positive electrode active material layer contains a positive electrode active material containing a carbon material. Containing, positive electrode precursor,
When the weight ratio of the alkali metal compound is X mass% based on the mass of the positive electrode precursor excluding the positive electrode current collector, 5 ≦ X ≦ 50.
In the element mapping obtained by SEM-EDX on the surface of the positive electrode precursor, when the area overlap ratio of carbon mapping with respect to oxygen mapping binarized based on the average value of brightness is A ₁ %, 30 ≤ A ₁ ≤ 90, positive electrode precursor.
[2]
In the element mapping obtained by SEM-EDX on the surface of the positive electrode precursor, when the area overlap ratio of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness is A ₂ %, 1 ≦ A ₂ ≦ The positive electrode precursor according to item 1, which is 50.
[3]
In the oxygen mapping obtained by SEM-EDX of the cross section of the positive electrode precursor processed by BIB, when the area of the oxygen mapping binarized based on the average value of the brightness is A ₃ %, 5 ≤ A ₃ ≤ 60. The positive electrode precursor according to item 1 or 2, which is present and 0.5 ≦ A _{3 /} X ≦ 2.0.
[4]
The positive electrode precursor according to any one of items 1 to 3, wherein the alkali metal compound is at least one selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate.
[5]
The positive electrode precursor according to any one of Items 1 to 4, wherein the alkali metal compound contains 10% by mass or more of lithium carbonate based on the total mass of the alkali metal compound.
[6]
The positive electrode precursor according to any one of Items 1 to 5, wherein the alkali metal compound has an average particle size of 0.1 μm or more and 10 μm or less.
[7]
The positive electrode precursor according to any one of items 1 to 6, wherein the positive electrode active material contains activated carbon as the carbon material.
[8]
The activated carbon has a mesopore amount of V ₁ (cc / g) derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method, and a micropore amount derived from pores having a diameter of less than 20 Å calculated by the MP method. When V ₂ (cc / g), 0.3 <V ₁ ≤ 0.8 and 0.5 ≤ V ₂ ≤ 1.0 are satisfied, and the specific surface area measured by the BET method is 1,500 m ^2. The positive electrode precursor according to item 7, which exhibits 3,000 m ² / g or less.
[9]
The activated carbon has a mesopore amount V ₁ (cc / g) derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method satisfies 0.8 <V ₁ ≤ 2.5, and the diameter calculated by the MP method. The amount of micropores V ₂ (cc / g) derived from pores less than 20 Å satisfies 0.8 <V ₂ ≤ 3.0, and the specific surface area measured by the BET method is 2,300 m ² / g or more 4 The positive electrode precursor according to item 7, which shows 000 m ² / g or less.

According to the present invention, it is possible to provide a positive electrode precursor capable of predoping the negative electrode in a short time and producing a non-aqueous hybrid capacitor having high energy density and high input / output.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the present embodiment. The upper limit value and the lower limit value in each numerical range of the present embodiment can be arbitrarily combined to form an arbitrary numerical range.

《Non-aqueous hybrid capacitor》
A non-aqueous hybrid capacitor generally has a positive electrode, a negative electrode, a separator, and an electrolytic solution as main components. As the electrolytic solution, an organic solvent in which an electrolyte such as an alkali metal salt is dissolved (hereinafter referred to as "non-aqueous electrolytic solution") is used.

In the present specification, the positive electrode state before pre-doping is defined as “positive electrode precursor”, and the positive electrode state after pre-doping is defined as “positive electrode”.

<Positive electrode precursor>
The positive electrode precursor in the present invention has an alkali metal compound other than the positive electrode active material, a positive electrode current collector, and a positive electrode active material layer on one side or both sides of the positive electrode current collector. When the weight ratio of the alkali metal compound is X mass% based on the mass of the positive electrode precursor containing the positive electrode active material including the carbon material and excluding the positive electrode current collector, 5 ≦ X ≦ 50. In the element mapping obtained by SEM-EDX on the surface of the positive electrode precursor, when the area overlap ratio of the carbon mapping with respect to the oxygen mapping binarized based on the average value of the brightness is A ₁ %, 30 ≦ A ₁ ≦ 90. The positive electrode precursor according to the present embodiment may be simply referred to as an electrode before pre-doping, a one-sided electrode before pre-doping, a half cell, a coating electrode, a dry electrode, or the like, depending on the desired configuration of the non-aqueous hybrid capacitor.

The positive electrode precursor of the present embodiment contains an alkali metal compound other than the positive electrode active material. In the present embodiment, when assembling the power storage element, it is preferable to pre-dope the negative electrode with alkali metal ions. As a pre-doping method, a voltage is applied between the positive electrode precursor and the negative electrode after assembling the power storage element using the positive electrode precursor containing the alkali metal compound, the negative electrode, the separator, and the non-aqueous electrolyte solution. Is preferable. The alkali metal compound is preferably contained in the positive electrode active material layer formed on the positive electrode current collector of the positive electrode precursor.

[Positive electrode active material layer]
The positive electrode active material layer contained in the positive electrode precursor contains a positive electrode active material containing a carbon material. The positive electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, if necessary, in addition to the positive electrode active material.

The positive electrode active material layer of the positive electrode precursor preferably contains an alkali metal compound other than the positive electrode active material.

-Positive electrode active material-
The positive electrode active material contains a carbon material. Examples of the carbon material include activated carbon, carbon nanotubes, a conductive polymer, a porous carbon material, and the like, and more preferably activated carbon. As the positive electrode active material, one type of carbon material may be used alone, or two or more types of carbon materials may be mixed and used, and materials other than the carbon material (for example, an alkali metal and a transition metal) may be used. (Composite oxide, etc.) may be included.

The content of the carbon material with respect to the total mass of the positive electrode active material is preferably 50% by mass or more, more preferably 70% by mass or more, or may be 100% by mass. From the viewpoint of obtaining a good effect when used in combination with other materials, for example, the content of the carbon material is preferably 90% by mass or less, or 80% by mass or less, based on the total mass of the positive electrode active material. You may.

When activated carbon is used as the positive electrode active material, the type of activated carbon and its raw material are not particularly limited. However, it is preferable to optimally control the pores of the activated carbon in order to achieve both high input / output characteristics and high energy density. Specifically, the amount of mesopores derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V ₁ (cc / g), and the amount of micropores derived from pores having a diameter of less than 20 Å calculated by the MP method. When is V ₂ (cc / g),
(1) In order to obtain high input / output characteristics, 0.3 <V ₁ ≤ 0.8 and 0.5 ≤ V ₂ ≤ 1.0 are satisfied, and the specific surface area measured by the BET method is 1. , 500 m ² / g or more and 3,000 m ² / g or less of activated carbon (hereinafter, also referred to as “activated carbon 1”) is preferable.
(2) In order to obtain a high energy density, 0.8 <V ₁ ≤ 2.5 and 0.8 <V ₂ ≤ 3.0 are satisfied, and the specific surface area measured by the BET method is 2, Activated carbon having a thickness of 300 m ² / g or more and 4,000 m ² / g or less (hereinafter, also referred to as “activated carbon 2”) is preferable.

Hereinafter, the above-mentioned (1) activated carbon 1 and the above-mentioned (2) activated carbon 2 will be described individually in sequence.

(Activated carbon 1)
Meso Anaryou V ₁ of the activated carbon 1, in terms of increasing the output characteristics when incorporated in the electric storage element is preferably 0.3 cc / g greater than. On the other hand, it is preferably 0.8 cc / g or less from the viewpoint of suppressing a decrease in the bulk density of the positive electrode. The above V ₁ is more preferably 0.35 cc / g or more and 0.7 cc / g or less, and further preferably 0.4 cc / g or more and 0.6 cc / g or less.

The micropore amount V ₂ of the activated carbon 1 is preferably 0.5 cc / g or more in order to increase the specific surface area and the capacity of the activated carbon. On the other hand, it is preferably 1.0 cc / g or less from the viewpoint of suppressing the bulk of the activated carbon, increasing the density as an electrode, and increasing the capacity per unit volume. The above V ₂ is more preferably 0.6 cc / g or more and 1.0 cc / g or less, and further preferably 0.8 cc / g or more and 1.0 cc / g or less.

The ratio of meso Anaryou _{V 1} relative to the micropore volume _{V 2} of activated carbon 1 _(V 1 / V ₂₎ is preferably in the range of _{0.3 ≦ V 1 / V 2 ≦} 0.9. That is, V ₁ / V ₂ is 0.3 or more from the viewpoint of increasing the ratio of the mesopore amount to the micropore amount to the extent that the deterioration of the input / output characteristics can be suppressed while maintaining the high capacity. Is preferable. On the other hand, V ₁ / V ₂ is preferably 0.9 from the viewpoint of increasing the ratio of the amount of micropores to the amount of mesopores to the extent that the decrease in capacitance can be suppressed while maintaining high input / output characteristics. Hereinafter, it is more preferably 0.4 ≦ V ₁ / V ₂ ≦ 0.7, and even more preferably 0.55 ≦ V ₁ / V ₂ ≦ 0.7.

For V ₁ , V ₂ and V ₁ / V ₂ of the activated carbon 1, the upper and lower limits of the suitable ranges described above can be arbitrarily combined.

The average pore diameter of the activated carbon 1 is preferably 17 Å or more, more preferably 18 Å or more, and even more preferably 20 Å or more, from the viewpoint of increasing the input / output of the obtained power storage element. From the viewpoint of increasing the capacity, the average pore diameter of the activated carbon 1 is preferably 25 Å or less.

BET specific surface area of the activated carbon 1 is preferably from 1,500 m ² / g or more 3,000 m ² / g, more preferably not more than 1,500 m ² / g or more 2,500 m ² / g. When the BET specific surface area is 1,500 m ² / g or more, a good energy density can be easily obtained, while when the BET specific surface area is 3,000 m ² / g or less, in order to maintain the strength of the electrode. Since it is not necessary to add a large amount of binder, the performance per electrode volume is improved. The upper and lower limits of the BET specific surface area range can be arbitrarily combined.

Activated carbon 1 having the above characteristics can be obtained, for example, by using the raw materials and treatment methods described below.

In the present embodiment, the carbon source used as the raw material of the activated carbon 1 is not particularly limited. For example, plant-based raw materials such as wood, wood flour, coconut shells, by-products during pulp production, bagas, waste sugar honey; peat, sub-charcoal, brown charcoal, bituminous charcoal, smokeless charcoal, petroleum distillation residue components, petroleum pitch, coke, coal tar, etc. Fossil raw materials; various synthetic resins such as phenol resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin, celluloid, epoxy resin, polyurethane resin, polyester resin, polyamide resin; polybutylene, polybutadiene, polychloroprene, etc. Synthetic rubber; other synthetic wood, synthetic pulp, etc., and carbonized products thereof. Among these raw materials, plant-based raw materials such as coconut shell and wood flour and their carbides are preferable, and coconut shell carbide is particularly preferable, from the viewpoint of mass production and cost.

As a carbonization and activation method for obtaining the activated carbon 1 from these raw materials, for example, known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method can be adopted.

Examples of the carbonization method for these raw materials include inert gases such as nitrogen, carbon dioxide, helium, argon, xenone, neon, carbon monoxide, and combustion exhaust gas, or other gases containing these inert gases as main components. Examples thereof include a method of firing at 400 to 700 ° C., preferably 450 to 600 ° C. for about 30 minutes to 10 hours using a mixed gas.

As a method for activating the carbide obtained by the above carbonization method, a gas activation method of firing using an activation gas such as steam, carbon dioxide, or oxygen is preferably used. Of these, a method using steam or carbon dioxide as the activating gas is preferable.

In this activation method, the above-mentioned carbide is preferably supplied for 3 to 12 hours while supplying the activation gas at a ratio of preferably 0.5 to 3.0 kg / h, more preferably 0.7 to 2.0 kg / h. It is more preferable to activate by raising the temperature to 800 to 1,000 ° C. over 5 to 11 hours, more preferably 6 to 10 hours.

Prior to the activation treatment of the carbide, the carbide may be first activated in advance. In this primary activation, a method in which a carbon material is usually fired at a temperature of less than 900 ° C. using an activation gas such as steam, carbon dioxide, or oxygen to activate the gas is preferable.

Activated carbon 1 having the above characteristics can be produced by appropriately combining the firing temperature and firing time in the carbonization method with the amount of activated gas supplied, the rate of temperature rise, and the maximum activation temperature in the activation method.

The average particle size of the activated carbon 1 is preferably 2 to 20 μm. When the average particle size is 2 μm or more, the capacity per electrode volume tends to be high because the density of the active material layer is high. If the average particle size is 2 μm or more, the durability is unlikely to decrease. On the other hand, when the average particle size is 20 μm or less, it tends to be easily adapted to high-speed charging / discharging of a non-aqueous hybrid capacitor. The average particle size is more preferably 2 to 15 μm, still more preferably 3 to 10 μm. The upper and lower limits of the average particle size range can be arbitrarily combined.

(Activated carbon 2)
Meso Anaryou V ₁ of the activated carbon 2, from the viewpoint of increasing the output characteristics when incorporated in the electric storage element is preferably 0.8 cc / g greater than. V ₁ is preferably 2.5 cc / g or less from the viewpoint of suppressing a decrease in the capacity of the power storage element. The above V ₁ is more preferably 1.0 cc / g or more and 2.0 cc / g or less, and further preferably 1.2 cc / g or more and 1.8 cc / g or less.

On the other hand, the micropore amount V ₂ of the activated carbon ₂ is preferably a value larger than 0.8 cc / g in order to increase the specific surface area and the capacity of the activated carbon. V ₂ is preferably 3.0 cc / g or less from the viewpoint of increasing the density of the activated carbon as an electrode and increasing the capacity per unit volume. The above V ₂ is more preferably larger than 1.0 cc / g and 2.5 cc / g or less, and further preferably 1.5 cc / g or more and 2.5 cc / g or less.

The activated carbon 2 having the above-mentioned meso-pore amount and micro-pore amount has a higher BET specific surface area than the activated carbon used for conventional electric double layer capacitors or lithium ion capacitors. The specific value of the BET specific surface area of the activated carbon 2 is preferably 2,300 m ² / g or more and 4,000 m ² / g or less. The lower limit of the BET specific surface area is more preferably 3,000 m ² / g or more, and further preferably 3,200 m ² / g or more. The upper limit of the BET specific surface area is more preferably 3,800 m ² / g or less. When the BET specific surface area is 2,300 m ² / g or more, good energy density can be easily obtained, while when the BET specific surface area is 4,000 m ² / g or less, in order to maintain the strength of the electrode. Since it is not necessary to add a large amount of binder, the performance per electrode volume is improved.

For the V ₁ , V ₂ and BET specific surface areas of the activated carbon 2, the upper and lower limits of the suitable ranges described above can be arbitrarily combined.

Activated carbon 2 having the above characteristics can be obtained by using, for example, the raw materials and treatment methods described below.

The carbon source used as a raw material for activated carbon 2 is not particularly limited as long as it is a carbon source normally used as a raw material for activated carbon. For example, plant-based raw materials such as wood, wood flour, and coconut shells; petroleum pitch, coke. Fossil-based raw materials such as, and various synthetic resins such as phenol resin, furan resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, and resorcinol resin can be mentioned. Among these raw materials, phenol resin and furan resin are particularly preferable because they are suitable for producing activated carbon having a high specific surface area.

Examples of the method of carbonizing these raw materials or the heating method at the time of activation treatment include known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method. As the atmosphere at the time of heating, an inert gas such as nitrogen, carbon dioxide, helium, or argon, or a gas containing these inert gases as a main component and mixed with other gases is used. The carbonization temperature is preferably 400 to 700 ° C., the lower limit is preferably 450 ° C. or higher, further preferably 500 ° C. or higher, the upper limit is preferably 650 ° C. or lower, and the firing time is preferably about 0.5 to 10 hours. is there.

Examples of the method for activating the carbide after the carbonization treatment include a gas activation method in which the carbide is fired using an activation gas such as steam, carbon dioxide, and oxygen, and an alkali metal activation method in which heat treatment is performed after mixing with an alkali metal compound. An alkali metal activation method is preferable for producing activated carbon having a high specific surface area.

In this activation method, the mass ratio of the carbide to the alkali metal compound such as potassium hydroxide (KOH) and sodium hydroxide (NaOH) is 1: 1 or more (the amount of the alkali metal compound is equal to or less than the amount of the carbide). After mixing to a large amount), heating is carried out in an inert gas atmosphere, preferably in the range of 600 to 900 ° C., more preferably 650 ° C. to 850 ° C. for 0.5 to 5 hours, and then the alkali metal. The compound is washed and removed with acid and water, and further dried.

The mass ratio of carbide to alkali metal compound (= carbide: alkali metal compound) is preferably 1: 1 or more, and the amount of mesopores increases as the amount of alkali metal compound increases, and the mass ratio is around 1: 3.5. Since the amount of pores tends to increase rapidly at the boundary, the mass ratio of the carbide and the alkali metal compound is preferably 1: 3 or more. The mass ratio of the carbide to the alkali metal compound increases as the amount of the alkali metal compound increases, but it is preferably 1: 5.5 or less in consideration of the treatment efficiency such as subsequent cleaning.

In order to increase the amount of micropores and not to increase the amount of mesopores, it is advisable to increase the amount of carbides at the time of activation and mix with KOH. In order to increase both the amount of micropores and the amount of mesopores, it is advisable to use a large amount of KOH. In order to increase the amount of mesopores, it is preferable to perform steam activation after performing alkali activation treatment.

The average particle size of the activated carbon 2 is preferably 2 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less.

(Usage mode of activated carbon)
When activated carbon is used as the positive electrode active material, activated carbons 1 and 2 may be one type of activated carbon, respectively, or a mixture of two or more types of activated carbon, and each of the above-mentioned characteristic values is shown as the whole mixture. It may be a thing.

As the activated carbons 1 and 2 described above, either one of them may be selected and used, or both may be mixed and used.

The positive electrode active material is a material other than activated carbon 1 and 2 (for example, activated carbon that does not have the specific V ₁ and / or V ₂ described above, or a material other than activated carbon (for example, a composite oxide of an alkali metal and a transition metal). )) May be included. The content of activated carbon 1, the content of activated carbon 2, or the total content of activated carbons 1 and 2, is preferably more than 50% by mass, more preferably 70% by mass or more, and 90% by mass, respectively, of the total positive electrode active material. % Or more is more preferable, and 100% by mass is even more preferable.

The content ratio of the positive electrode active material in the positive electrode active material layer is preferably 35% by mass or more and 95% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode precursor. The upper limit of the content ratio of the positive electrode active material is more preferably 45% by mass or more, and further preferably 55% by mass or more. The lower limit of the content ratio of the positive electrode active material is more preferably 90% by mass or less, and further preferably 80% by mass or less. By setting the content ratio in this range, suitable charge / discharge characteristics are exhibited.

-Alkali metal compound-
As the alkali metal compound in the present embodiment, a compound capable of decomposing in the positive electrode precursor to release alkali metal ions is used. Carbonates, oxides, hydroxides, fluorides, chlorides, oxalates, iodides, nitrides, sulfides, phosphides, glass oxides, sulfates, phosphates, oxalates that use alkali metal ions as cations. At least one selected from the group consisting of oxides, gear oxides and acetates is preferably used. Among them, carbonates, oxides, and hydroxides are more preferable, and alkali metal carbonates are more preferably used from the viewpoint that they can be handled in the air and have low hygroscopicity. As the alkali metal carbonate, at least one selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate is preferably used, and among them, from the viewpoint of high capacity per unit weight. Lithium carbonate is more preferably used. The alkali metal compound preferably contains 10% by mass or more of lithium carbonate based on the total mass of the alkali metal compounds contained in the positive electrode precursor. The alkali metal compound contained in the positive electrode precursor may be one kind or two or more kinds.

The positive electrode precursor of the present embodiment is at least one selected from the group consisting of alkaline earth metal carbonates such as BeCO ₃ , MgCO ₃ , CaCO ₃ , SrCO ₃ , and BaCO ₃ , in addition to the alkali metal compound. It may contain one or more alkaline earth metal oxides, alkaline earth metal hydroxides, alkaline earth metal halides, alkaline earth metal oxalates, and alkaline earth metal carboxylates.

In the present embodiment, when the weight ratio of the alkali metal compound in the positive electrode precursor is X% by mass based on the mass of the positive electrode precursor excluding the positive electrode current collector, 5 ≦ X ≦ 50, preferably 10 ≦. X ≦ 45, more preferably 15 ≦ X ≦ 40.

When X is 5 or more, the alkali metal ions pre-doped into the negative electrode can be sufficiently secured, and the positive electrode can be provided with an appropriate degree of porosity, so that the input / output characteristics of the non-aqueous hybrid capacitor are enhanced. When X is 50 or less, the electron conductivity in the positive electrode precursor is enhanced, so that the decomposition of the alkali metal compound is promoted, so that predoping is completed in a short time and a high energy density non-aqueous hybrid capacitor is obtained. Be done.

When the positive electrode precursor contains the above alkaline earth metal compound in addition to the alkali metal compound, the total mass of the alkali metal compound and the alkaline earth metal compound is based on the mass of the positive electrode precursor excluding the positive electrode current collector. It is preferable to prepare the positive electrode precursor so that it is contained in a proportion of 5% by mass or more and 50% by mass or less.

The quantification of the alkali metal element and the alkaline earth metal can be calculated by ICP-AES, atomic absorption spectrometry, fluorescent X-ray analysis, neutron activation analysis, ICP-MS and the like.

(Elemental mapping of positive electrode precursor)
The alkali metal compound contained in the positive electrode precursor is oxidatively decomposed by applying a high voltage when a non-aqueous hybrid capacitor is formed to release alkali metal ions, and is reduced at the negative electrode to proceed with predoping. Therefore, pre-doping can be performed in a short time by promoting the oxidation reaction. In order to promote the oxidation reaction, an alkali metal compound, which is an insulator, is brought into contact with a conductive member such as a positive electrode active material and / or a conductive filler to ensure electron conductivity, and the cations released in response to the reaction. It is important to diffuse the ions into the electrolyte.

In the present embodiment, in the element mapping obtained by the scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) on the surface of the positive electrode precursor, carbon for oxygen mapping binarized based on the average value of brightness. When the area overlap rate of the mapping is A ₁ %, it is 30 ≦ A ₁ ≦ 90, preferably 35 ≦ A ₁ ≦ 85, and more preferably 40 ≦ A ₁ ≦ 80.

It is presumed that oxygen in the element mapping in SEM-EDX is mainly derived from the alkali metal compound, and carbon is mainly derived from the carbon material which is the positive electrode active material and / or the conductive filler.

When A ₁ is 30% or more, pre-doping is promoted because the electron conductivity between the alkali metal compound and the conductive member such as the positive electrode active material and / or the conductive filler is ensured, and the positive electrode becomes porous. When added, a non-aqueous hybrid capacitor with high input / output can be obtained. When A ₁ is 90% or less, diffusion of alkali metal ions in the electrolytic solution is promoted, so that predoping is promoted.

In the element mapping obtained by SEM-EDX on the surface of the positive electrode precursor, when the area overlap rate of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness is A ₂ %, preferably 1 ≦ A ₂ ≦ 50, more preferably 1.5 ≦ A ₂ ≦ 40, still more preferably 2 ≦ A ₂ ≦ 30.

Fluorine in elemental mapping in SEM-EDX is considered to be mainly derived from the binder.

When A ₂ is 1% or more, the alkali metal compound is sufficiently fixed in the positive electrode precursor. When A ₂ is 50% or less, the alkali metal compound is not hindered by the binder which is an insulator, and pre-doping is promoted because electron conductivity is ensured.

In broad ion beam (BIB) processing oxygen mapping obtained by SEM-EDX of the positive electrode precursor sectional, when the area of the oxygen mapping binarized on the basis of the average value of the brightness and A _3%, preferably, 5 ≦ A ₃ ≦ 60 and 0.5 ≦ A _{3 /} X ≦ 2.0.

When A ₃ is 5% or more, pre-doping is promoted because the electron conductivity between the alkali metal compound and the conductive member such as the positive electrode active material and / or the conductive filler is ensured. When A ₃ is 60% or less, diffusion of alkali metal ions in the electrolytic solution is promoted, so that predoping is promoted. When A ₃ / X is 0.5 or more, diffusion of the electrolytic solution in the positive electrode precursor is promoted, so that predoping is promoted. When A ₃ / X is 2.0 or less, pre-doping is promoted because the electron conductivity between the alkali metal compound and the conductive member such as the positive electrode active material and / or the conductive filler is ensured.

As a method for measuring A ₁ , A ₂ , and A ₃ , oxygen mapping obtained by binarizing the average value of brightness in the element mapping obtained by SEM-EDX on the surface of the positive electrode precursor and the cross section of the positive electrode precursor, It is calculated by finding the area of carbon mapping and fluorine mapping. As a method for forming the cross section of the positive electrode precursor, BIB processing can be used in which an Ar beam is irradiated from the upper part of the positive electrode precursor to prepare a smooth cross section along the end portion of the shielding plate installed directly above the sample.

The measurement conditions for element mapping of SEM-EDX are not particularly limited, but the number of pixels is preferably in the range of 128 × 128 pixels to 512 × 512 pixels, and the brightness is such that there are no pixels that reach the maximum brightness. It is preferable to adjust the brightness and contrast so that the average value falls within the range of 40% to 60% brightness.

(Aspect of alkali metal compound)
The alkali metal compound and the alkaline earth metal compound are preferably in the form of particles. The average particle size of the alkali metal compound contained in the positive electrode precursor is preferably 0.1 μm or more and 10 μm or less. The lower limit of the average particle size of the alkali metal compound is more preferably 0.3 μm or more, and further preferably 0.5 μm or more.

When the average particle size of the alkali metal compound is 0.1 μm or more, the dispersibility in the positive electrode precursor is excellent. When the average particle size of the alkali metal compound is 10 μm or less, the surface area of the alkali metal compound increases, so that the decomposition reaction proceeds efficiently.

The method for measuring the average particle size of the alkali metal compound in the positive electrode precursor is not particularly limited, but it can be calculated from the SEM image of the cross section of the positive electrode precursor and the SEM-EDX image.

Various methods can be used for micronizing the alkali metal compound and the alkaline earth metal compound. For example, a crusher such as a ball mill, a bead mill, a ring mill, a jet mill, or a rod mill can be used.

(Method of distinguishing between alkali metal compound and positive electrode active material)
The alkali metal compound and the positive electrode active material can be identified by oxygen mapping using an SEM-EDX image of a cross section of the positive electrode precursor measured at an observation magnification of 1000 to 4000 times. With respect to the oxygen mapping obtained by the SEM-EDX, particles containing 50% or more of bright areas binarized based on the average value of brightness can be discriminated as an alkali metal compound.

(Method of calculating the average particle size of alkali metal compounds)
The average particle size of the alkali metal compound can be obtained by image analysis of an image obtained from the cross-section SEM-EDX measured in the same field as the positive electrode precursor cross-section SEM. For all the particles of the alkali metal compound identified by the SEM image of the cross section of the positive electrode precursor, the cross-sectional area S is obtained, and the particle diameter d calculated by the following formula (1) is obtained. (The circumference ratio is π.)
d = 2 × (S / π) ^1/2 equation (1)

Using the obtained particle diameter d, the volume average particle diameter X ₀ is obtained by the following formula (2).
X ₀ = Σ [4 / 3π × (d / 2)] ³ × d] / Σ [4 / 3π × (d / 2)] ³ ] Equation (2)
By changing the field of view of the positive electrode precursor sectional measured over five locations, it is possible to calculate the average particle size of the alkali metal compound with an average value of the respective X _0.

-Arbitrary component of positive electrode active material layer-
The positive electrode active material layer of the positive electrode precursor in the present embodiment may contain optional components such as a conductive filler, a binder, and a dispersion stabilizer in addition to the positive electrode active material and the alkali metal compound, if necessary. Good.

The conductive filler is not particularly limited, and for example, acetylene black, ketjen black, vapor-grown carbon fibers, graphite, carbon nanotubes, a mixture thereof, and the like can be used. The amount of the conductive filler used in the positive electrode active material layer of the positive electrode precursor is preferably more than 0 parts by mass and 30 parts by mass or less, more preferably 0.01 parts by mass or more and 20 parts by mass with respect to 100 parts by mass of the positive electrode active material. Hereinafter, it is more preferably 1 part by mass or more and 15 parts by mass or less. As described above, the conductive filler promotes oxidative decomposition during pre-doping by contacting with the alkali metal compound, and from the viewpoint of high input / output characteristics, the positive electrode active material layer preferably contains the conductive filler. .. When the amount of the conductive filler used is 30 parts by mass or less, the content ratio of the positive electrode active material in the positive electrode active material layer increases, so that the energy density per volume of the positive electrode active material layer can be secured.

The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like. Can be used. When used in the positive electrode active material layer, it is preferable to use PVdF or PTFE from the viewpoint of oxidation resistance and electrode strength, and it is more preferable to use PVdF from the viewpoint of high input / output.

The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 27 parts by mass or less, and further preferably 5 parts by mass or more and 25 parts by mass with respect to 100 parts by mass of the positive electrode active material. It is less than a part. When the amount of the binder used is 1 part by mass or more, sufficient electrode strength is exhibited. On the other hand, when the amount of the binder used is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting the ingress and egress and diffusion of ions into the positive electrode active material.

The dispersion stabilizer is not particularly limited, and for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used. The amount of the dispersion stabilizer used is preferably 0 parts by mass or 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. When the amount of the dispersion stabilizer used is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry / exit and diffusion of ions into the positive electrode active material.

[Positive current collector]
The material constituting the positive electrode current collector in the present embodiment is not particularly limited as long as it is a material having high electron conductivity and less likely to deteriorate due to elution into an electrolytic solution and reaction with an electrolyte or ions, and is not particularly limited. Is preferable. As the metal foil as the positive electrode current collector, an aluminum foil is particularly preferable.

The positive electrode current collector may be a metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. A metal foil having through holes such as an etching foil may be used.
Among them, the positive electrode current collector is preferably a metal foil having no through hole. If there is no through hole, the manufacturing cost is low, the thin film can be easily formed, which contributes to high energy density, and the current collecting resistance can be lowered, so that high input / output characteristics can be obtained.

The thickness of the positive electrode current collector is not particularly limited as long as the shape and strength of the positive electrode can be sufficiently maintained, and is preferably 1 to 100 μm, for example.

[Manufacturing of positive electrode precursor]
In the present embodiment, the positive electrode precursor serving as the positive electrode of the non-aqueous hybrid capacitor can be manufactured by a known electrode manufacturing technique in a lithium ion battery, an electric double layer capacitor, or the like. For example, a positive electrode active material, an alkali metal compound, and other optional components used as necessary are dispersed or dissolved in water or an organic solvent to prepare a slurry coating solution, and this coating solution is used. A positive electrode precursor can be obtained by coating one side or both sides of the positive electrode current collector to form a coating film and drying the coating. The obtained positive electrode precursor may be pressed to adjust the thickness or bulk density of the positive electrode active material layer. Alternatively, without the use of a solvent, the positive electrode active material and the alkali metal compound, as well as other optional components used as needed, are mixed dry and the resulting mixture is press molded to form a positive electrode sheet. After the production, it is also possible to attach it to the positive electrode current collector using a conductive adhesive (also referred to as "conductive paste").

The coating liquid of the positive electrode precursor may be a dry blend of some or all of various material powders containing the positive electrode active material, and then water or an organic solvent may be added and / or a binder or dispersion thereof. A liquid or slurry-like substance in which a stabilizer is dissolved or dispersed may be added and prepared. A coating liquid may be prepared by adding various material powders containing a positive electrode active material to a liquid or slurry substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent. As a method of dry blending, for example, a positive electrode active material and an alkali metal compound are premixed using a ball mill or the like, and if necessary, a conductive filler is premixed to coat a low conductive alkali metal compound with the conductive filler. You may mix. Premixing facilitates decomposition of the alkali metal compound in the positive electrode precursor in the predoping described below. When water is used as the solvent of the coating liquid, the coating liquid may become alkaline by adding an alkali metal compound, and therefore a pH adjuster may be added if necessary.

The method for dispersing the coating liquid of the positive electrode precursor is not particularly limited, and a homodisper, a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirl type high-speed mixer, or the like can be preferably used. In order to obtain a coating liquid in a good dispersed state, it is preferable to disperse at a peripheral speed of 1 m / s or more and 50 m / s or less. When the peripheral speed is 1 m / s or more, various materials are preferably dissolved or dispersed. When the peripheral speed is 50 m / s or less, various materials are less likely to be destroyed by heat or shearing force due to dispersion, and reaggregation is less likely to occur, which is preferable.

The dispersity of the coating liquid is preferably such that the particle size measured by the grain gauge is 0.1 μm or more and 100 μm or less. The upper limit of the dispersity is more preferably a particle size of 80 μm or less, and further preferably a particle size of 50 μm or less. If the particle size is less than 0.1 μm, the size is smaller than the particle size of various material powders containing the positive electrode active material, and the material is crushed during the preparation of the coating liquid, which is not preferable. When the particle size is 100 μm or less, clogging at the time of discharging the coating liquid and streaks of the coating film are less likely to occur, and stable coating can be performed.

The viscosity (ηb) of the coating liquid of the positive electrode precursor is preferably 1,000 mPa · s or more and 20,000 mPa · s or less, more preferably 1,500 mPa · s or more and 10,000 mPa · s or less, and further preferably 1. , 700 mPa · s or more and 5,000 mPa · s or less. When the viscosity (ηb) is 1,000 mPa · s or more, liquid dripping during coating film formation is suppressed, and the coating film width and thickness can be satisfactorily controlled. When the viscosity (ηb) is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using the coating machine is small and stable coating can be performed, and the coating film thickness can be controlled to be less than the desired coating film thickness. ..

The TI value (thixotropy index value) of the coating liquid is preferably 1.1 or more, more preferably 1.2 or more, and further preferably 1.5 or more. When the TI value is 1.1 or more, the coating film width and thickness can be satisfactorily controlled.

The method for forming the coating film of the positive electrode precursor is not particularly limited, and a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by a single-layer coating or a multi-layer coating. In the case of multi-layer coating, the coating liquid composition may be adjusted so that the content of the alkali metal compound in each layer of the coating film is different. The coating speed is preferably 0.1 m / min or more and 100 m / min or less, more preferably 0.5 m / min or more and 70 m / min or less, and further preferably 1 m / min or more and 50 m / min or less. If the coating speed is 0.1 m / min or more, stable coating can be performed. If the coating speed is 100 m / min or less, sufficient coating accuracy can be ensured.

The method for drying the coating film of the positive electrode precursor is not particularly limited, and a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. The coating film may be dried by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower, more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. When the drying temperature is 200 ° C. or lower, cracks in the coating film due to rapid volatilization of the solvent, uneven distribution of the binder due to migration, and oxidation of the positive electrode current collector and the positive electrode active material layer can be suppressed.

The method for pressing the positive electrode precursor is not particularly limited, and a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The thickness, bulk density, and electrode strength of the positive electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later.

The press pressure is preferably 0.5 kN / cm or more and 20 kN / cm or less, more preferably 1 kN / cm or more and 10 kN / cm or less, and further preferably 2 kN / cm or more and 7 kN / cm or less. When the press pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. When the press pressure is 20 kN / cm or less, the positive electrode precursor does not bend or wrinkle, and the desired positive electrode active material layer thickness and bulk density can be adjusted.

A person skilled in the art can set an arbitrary value for the gap between the press rolls according to the thickness of the positive electrode precursor after drying so as to have a desired thickness and bulk density of the positive electrode active material layer. Those skilled in the art can set the press speed to any speed at which the positive electrode precursor is less likely to bend or wrinkle.

The surface temperature of the pressed portion may be room temperature, or the pressed portion may be heated if necessary. The lower limit of the surface temperature of the pressed portion at the time of heating is preferably a melting point of minus 60 ° C. or higher, more preferably minus 45 ° C. or higher, and even more preferably minus 30 ° C. or higher of the melting point of the binder to be used. The upper limit of the surface temperature of the pressed portion at the time of heating is preferably the melting point of the binder used plus 50 ° C. or lower, more preferably the melting point plus 30 ° C. or lower, and further preferably the melting point plus 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, the surface temperature of the pressed portion is preferably 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. It is ℃ or more and 170 ℃ or less. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, the surface temperature of the pressed portion is preferably 40 ° C. or higher and 150 ° C. or lower, more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. It is ℃ or more and 120 ℃ or less.

The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry, differential scanning calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a heating rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature is raised, and the endothermic peak temperature in the temperature raising process becomes the melting point.

The press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The thickness of the positive electrode active material layer is preferably 20 μm or more and 200 μm or less, more preferably 25 μm or more and 100 μm or less, and further preferably 30 μm or more and 80 μm or less per one side of the positive electrode current collector. When the thickness of the positive electrode active material layer is 20 μm or more, sufficient charge / discharge capacity can be exhibited. When the thickness of the positive electrode active material layer is 200 μm or less, the ion diffusion resistance in the electrode can be kept low. Therefore, sufficient input / output characteristics can be obtained, the cell volume can be reduced, and therefore the energy density can be increased. The upper and lower limits of the thickness range of the positive electrode active material layer can be arbitrarily combined. In the present specification, the thickness of the positive electrode active material layer when the current collector has through holes or irregularities means the average value of the thickness per side of the portion of the current collector that does not have through holes or irregularities. ..

<Negative electrode>
The negative electrode generally has a negative electrode current collector and a negative electrode active material layer existing on one side or both sides of the negative electrode current collector.

[Negative electrode active material layer]
The negative electrode active material layer preferably contains a negative electrode active material capable of occluding and releasing alkali metal ions. The negative electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, if necessary, in addition to the negative electrode active material.

-Negative electrode active material-
As the negative electrode active material, a substance capable of occluding and releasing alkali metal ions can be used. Specific examples of the negative electrode active material include carbon materials, titanium oxides, silicon, silicon oxides, silicon alloys, silicon compounds, tin and tin compounds. The content of the carbon material with respect to the total mass of the negative electrode active material may be preferably 50% by mass or more, more preferably 70% by mass or more, or 100% by mass. From the viewpoint of obtaining a good effect by using other materials in combination, the content of the carbon material is preferably, for example, 90% by mass or less, and may be 80% by mass or less. The upper and lower limits of the carbon material content range can be arbitrarily combined.

Examples of the carbon material include non-graphitizable carbon materials; easily graphitizable carbon materials; carbon black; carbon nanoparticles; activated carbon; artificial graphite; natural graphite; graphitized mesophase carbon globules; graphite whiskers; polyacene-based substances. Amorphous carbonaceous materials such as; carbonaceous materials obtained by heat-treating a carbonaceous material precursor; thermal decomposition products of furfuryl alcohol resin or novolak resin; fullerene; carbon nanophones; and composite carbon materials thereof. it can. The carbonaceous material precursor is not particularly limited as long as it becomes a carbonic material by heat treatment, for example, petroleum-based pitch, coal-based pitch, mesocarbon microbeads, coke, and synthetic resin (for example, phenol). Resin, etc.).

-Arbitrary component of negative electrode active material layer-
If necessary, the negative electrode active material layer may contain optional components such as a conductive filler, a binder, and a dispersion stabilizer in addition to the negative electrode active material.

The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor-grown carbon fiber. The amount of the conductive filler used is preferably more than 0 parts by mass and 30 parts by mass or less, more preferably 0.01 parts by mass or more and 20 parts by mass or less, and further preferably 0.1 parts by mass with respect to 100 parts by mass of the negative electrode active material. More than 15 parts by mass or less.

The binder is not particularly limited, and for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like can be used. it can. The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 2 parts by mass or more and 27 parts by mass or less, and further preferably 3 parts by mass or more and 25 parts by mass with respect to 100 parts by mass of the negative electrode active material. It is less than a part. When the amount of the binder used is 1 part by mass or more, sufficient electrode strength is exhibited. On the other hand, when the amount of the binder used is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry and exit of alkali metal ions into the negative electrode active material.

The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used. The amount of the dispersion stabilizer used is preferably more than 0 parts by mass or 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the negative electrode active material. When the amount of the dispersion stabilizer used is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry and exit of alkali metal ions into the negative electrode active material.

[Negative electrode current collector]
The material constituting the negative electrode current collector is preferably a metal foil having high electron conductivity and less likely to deteriorate due to elution into an electrolytic solution and reaction with an electrolyte or ions. Such metal foil is not particularly limited, and examples thereof include aluminum foil, copper foil, nickel foil, and stainless steel foil. Copper foil is preferable as the negative electrode current collector in the non-aqueous hybrid capacitor.

The metal foil may be a metal foil having no irregularities or through holes, or a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etching, etc. A metal foil having through holes such as a foil may be used.
Among them, the negative electrode current collector is preferably a metal foil having no through hole. If there is no through hole, the manufacturing cost is low, the thin film can be easily formed, which contributes to high energy density, and the current collecting resistance can be lowered, so that high input / output characteristics can be obtained.

The thickness of the negative electrode current collector is not particularly limited as long as the shape and strength of the negative electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example.

[Manufacturing of negative electrode]
The negative electrode has a negative electrode active material layer on one side or both sides of the negative electrode current collector. In a typical embodiment, the negative electrode active material layer is fixed to the negative electrode current collector.

The negative electrode can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors and the like. For example, various materials including a negative electrode active material are dispersed or dissolved in water or an organic solvent to prepare a slurry coating liquid, and this coating liquid is applied to one or both sides of a negative electrode current collector. A negative electrode can be obtained by forming a coating film and drying it. Further, the obtained negative electrode may be pressed to adjust the film thickness and bulk density of the negative electrode active material layer.

The thickness of the negative electrode active material layer is preferably 5 μm or more and 100 μm or less per side. When this thickness is 5 μm or more, no streaks or the like are generated when the negative electrode active material layer is applied, and the coatability is excellent. When this thickness is 100 μm or less, high energy density can be developed by reducing the cell volume. The upper and lower limits of the thickness range of the negative electrode active material layer can be arbitrarily combined. The thickness of the negative electrode active material layer when the current collector has through holes or irregularities means the average value of the thickness per side of the portion of the current collector that does not have through holes or irregularities.

The bulk density of the negative electrode active material layer is preferably 0.30 g / cm ³ or more and 1.8 g / cm ³ or less. When the bulk density is 0.30 g / cm ³ or more, sufficient strength can be maintained and sufficient conductivity between the negative electrode active materials can be exhibited. When the bulk density is 1.8 g / cm ³ or less, pores capable of sufficiently diffusing ions can be secured in the negative electrode active material layer.

<Separator>
The positive electrode precursor and the negative electrode can be laminated, laminated and wound through a separator to form an electrode laminate or an electrode wound body having a positive electrode precursor, a separator, and a negative electrode.

As the separator, a polyethylene microporous membrane or polypropylene microporous membrane used in a lithium ion secondary battery, a cellulose non-woven paper used in an electric double layer capacitor, or the like can be used. A film composed of organic or inorganic fine particles may be laminated on one side or both sides of these separators. Organic or inorganic fine particles may be contained inside the separator.

The thickness of the separator is preferably 5 μm or more and 35 μm or less. A thickness of 5 μm or more is preferable because self-discharge due to internal microshorts tends to be small. A thickness of 35 μm or less is preferable because the input / output characteristics of the power storage element tend to be improved.

The thickness of the film composed of organic or inorganic fine particles is preferably 1 μm or more and 10 μm or less. A thickness of 1 μm or more is preferable because self-discharge due to internal microshorts tends to be small. A thickness of 10 μm or less is preferable because the input / output characteristics of the power storage element tend to be improved.

<Exterior body>
As the exterior body, a metal can, a laminated film, or the like can be used. The metal can is preferably made of aluminum. As the laminated film, a film in which a metal foil and a resin film are laminated is preferable, and a three-layer structure composed of an outer layer resin film / metal foil / inner layer resin film is exemplified. The outer layer resin film is for preventing the metal foil from being damaged by contact or the like, and a resin such as nylon or polyester can be preferably used. The metal foil is for preventing the permeation of moisture and gas, and foils such as copper, aluminum, and stainless steel can be preferably used. The inner layer resin film protects the metal foil from the electrolytic solution stored inside and melts and seals the outer body at the time of heat sealing, and polyolefins, acid-modified polyolefins and the like can be preferably used.

<Non-aqueous electrolyte>
The electrolytic solution used for the non-aqueous hybrid capacitor is preferably a non-aqueous electrolytic solution. That is, the electrolytic solution contains a non-aqueous solvent. The non-aqueous electrolyte solution contains an alkali metal salt of 0.5 mol / L or more based on the total amount of the non-aqueous electrolyte solution. That is, the non-aqueous electrolyte solution contains an alkali metal salt as an electrolyte. Examples of the non-aqueous solvent contained in the non-aqueous electrolyte solution include cyclic carbonates typified by ethylene carbonate and propylene carbonate, and chain carbonates typified by dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and the like.

<< Manufacturing method of non-aqueous hybrid capacitor >>
<Assembly>
Typically, the positive electrode precursor and the negative electrode cut into a single-wafer shape are laminated via a separator to obtain an electrode laminate, and the positive electrode terminal and the negative electrode terminal are connected to the electrode laminate. Alternatively, the positive electrode precursor and the negative electrode are laminated and wound via a separator to obtain an electrode wound body, and the positive electrode terminal and the negative electrode terminal are connected to the electrode wound body. The shape of the electrode winding body may be cylindrical or flat.

The method of connecting the positive electrode terminal and the negative electrode terminal is not particularly limited, and a method such as resistance welding or ultrasonic welding can be used.

It is preferable that the electrode laminate or the electrode wound body to which the terminals are connected is dried to remove the residual solvent. It is not limited to the drying method, and is dried by vacuum drying or the like. The residual solvent is preferably 1.5% by mass or less per weight of the positive electrode active material layer or the negative electrode active material layer. If the residual solvent is more than 1.5% by mass, the solvent remains in the system and the self-discharge characteristics are deteriorated, which is not preferable.

The dried electrode laminate or electrode wound body is preferably stored in an exterior body typified by a metal can or a laminate film in a dry environment with a dew point of -40 ° C or less, leaving only one opening. It is preferable to seal it in a fresh state. If the dew point is higher than −40 ° C., water may adhere to the electrode laminate or the electrode winding body, and water may remain in the system, deteriorating the self-discharge characteristics. The sealing method of the outer body is not particularly limited, and a method such as heat sealing or impulse sealing can be used.

<Liquid injection, impregnation, sealing>
After assembly, the non-aqueous electrolyte solution is injected into the electrode laminate or electrode winding body housed in the exterior body. After pouring, it is desirable to sufficiently impregnate the positive electrode precursor, negative electrode, and separator with a non-aqueous electrolytic solution. When the electrolytic solution is not immersed in at least a part of the positive electrode precursor, the negative electrode, and the separator, the doping proceeds non-uniformly in the pre-doping described later, so that the resistance of the obtained non-aqueous hybrid capacitor increases or the resistance of the obtained non-aqueous hybrid capacitor increases. Durability is reduced. The impregnation method is not particularly limited. For example, a non-aqueous hybrid capacitor after injection is installed in a decompression chamber with the exterior body open, and the inside of the chamber is decompressed using a vacuum pump. A method of returning to atmospheric pressure or the like can be used. After impregnation, the non-aqueous hybrid capacitor with the outer body open is sealed while reducing the pressure.

<Pre-dope>
As a preferable predoping method, a voltage is applied between the positive electrode precursor and the negative electrode to decompose the alkali metal compound in the positive electrode precursor to release alkali metal ions, and the alkali metal ions are reduced at the negative electrode. A method of pre-doping the negative electrode active material layer with alkali metal ions can be mentioned.

In pre-doping, gas such as CO ₂ is generated due to oxidative decomposition of the alkali metal compound in the positive electrode precursor. Therefore, when applying a voltage, it is preferable to take measures to release the generated gas to the outside of the exterior body. As this means, for example, a method of applying a voltage with a part of the exterior body opened; a state in which an appropriate gas release means such as a gas vent valve or a gas permeable film is installed in advance on a part of the exterior body. A method of applying a voltage; etc. can be mentioned.

<Aging>
After completion of pre-doping, it is preferable to age the non-aqueous hybrid capacitor. During aging, the solvent in the electrolytic solution is decomposed at the negative electrode, and an alkali gold ion permeable solid polymer film is formed on the surface of the negative electrode.

The aging method is not particularly limited, but for example, a method of reacting the solvent in the electrolytic solution in a high temperature environment can be used.

<Degassing>
After the aging is completed, it is preferable to further degas to surely remove the gas remaining in the electrolytic solution, the positive electrode, and the negative electrode. In a state where gas remains in at least a part of the electrolytic solution, the positive electrode, and the negative electrode, ionic conduction is inhibited, so that the resistance of the obtained non-aqueous hybrid capacitor increases.

The degassing method is not particularly limited, and for example, a method of installing a non-aqueous hybrid capacitor in a decompression chamber with the exterior body open and depressurizing the inside of the chamber using a vacuum pump is used. be able to.

<Characteristic evaluation of power storage element>
(Capacitance)
In the present specification, the capacitance F (F) is a value obtained by the following method.
First, in a constant temperature bath in which the cell corresponding to the non-aqueous hybrid capacitor is set to 25 ° C., constant current charging is performed until the current value of 2C reaches 3.8V, and then a constant voltage of 3.8V is applied. Constant voltage charging is performed for a total of 30 minutes. After that, let Q be the capacitance when constant current discharge is performed with a current value of 2C up to 2.2V. It means a value calculated by F = Q / (3.8-2.2) using the Q obtained here.

Here, the C rate of the current is the current value at which the discharge is completed in one hour when the constant current discharge is performed from the upper limit voltage to the lower limit voltage, and is referred to as 1C. In the present specification, 1C is the current value at which the discharge is completed in 1 hour when the constant current discharge is performed from the upper limit voltage of 3.8 V to the lower limit voltage of 2.2 V.

(Internal resistance)
In the present specification, the internal resistance Ra (Ω) is a value obtained by the following method.
First, a non-aqueous hybrid capacitor is charged with a constant current in a constant temperature bath set at 25 ° C. until it reaches 3.8 V with a current value of 20 C, and then a constant voltage charge with a constant voltage of 3.8 V is applied. For 30 minutes. Subsequently, a constant current discharge is performed up to 2.2 V with a current value of 20 C to obtain a discharge curve (time-voltage). In this discharge curve, when the voltage at the discharge time = 0 seconds obtained by extrapolating from the voltage values at the discharge times of 2 seconds and 4 seconds is set to Vo, the drop voltage ΔV = 3.8- It is a value calculated by Vo and Ra = ΔV / (current value of 20C).

(Electric energy)
In the present specification, the electric energy E (Wh) is a value obtained by the following method.
Using the capacitance F (F) calculated by the method described above,
It refers to the value calculated by F × (3.8 ² -2.2 ² ) / 2/3600.

(volume)
The volume V (L) of the power storage element refers to the volume of the portion of the electrode laminate or the electrode wound body in which the positive electrode active material layer and the negative electrode active material layer are stacked and is housed by the exterior body.

For example, in the case of an electrode laminate or an electrode wound body housed by a laminate film, a region of the electrode laminate or the electrode wound body in which the positive electrode active material layer and the negative electrode active material layer are present is cup-molded. Although it is housed in the laminated film, the volume (V _x ) of this power storage element is the outer dimension length (l _x ) and outer dimension width (w _x ) of the cup molded portion, and the storage including the laminated film. It is calculated by V _x = l _x x w _x x t _{x according} to the thickness of the element (t _x ).

In the case of an electrode laminate or an electrode winding body housed in a square metal can, the volume of the power storage element is simply the volume of the outer dimension of the metal can. That is, the volume of the storage element _{(V y),} the outer dimensions length of the square of the metal can _{(l y)} to the outer dimension width _(w y), the outer dimensions thickness _{(t y), V y =} l y It is calculated by × w _y × t _y .

Even in the case of an electrode winding body housed in a cylindrical metal can, the volume of the power storage element in the outer dimensions of the metal can is used. That is, the volume (V _z ) of this power storage element depends on the outer radius (r) and the outer dimension length (l _z ) of the bottom surface or the upper surface of the cylindrical metal can, and V _z = 3.14 × r × r. It is calculated by × l _z .

"Measuring method"
<BET specific surface area, mesopore amount, micropore amount, average pore diameter>
The BET specific surface area, the amount of mesopores, the amount of micropores, and the average pore diameter in the present embodiment are values obtained by the following methods, respectively. The sample is vacuum-dried at 200 ° C. for 24 hours, and the isotherms of adsorption and desorption are measured using nitrogen as an adsorbent. Using the adsorption-side isotherms obtained here, the BET specific surface area is calculated by the BET multipoint method or the BET1 point method, the mesopore amount is calculated by the BJH method, and the micropore amount is calculated by the MP method.

The BJH method is a calculation method generally used for the analysis of mesopores, and was proposed by Barrett, Joiner, Hallenda et al. (E.P. Barrett, L.G. Joiner and P. Hallenda, J. Am. Chem. Soc., 73, 373 (1951)).

The MP method is a micropore volume, a micropore area, and a micropore using the "t-plot method" (BC Lippens, JH de Boer, J. Catalysis, 4319 (1965)). It means a method for obtaining the distribution of R. S. It is a method devised by Mikhair, Brunauer, and Bodor (RS Mikhair, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)).

The average pore diameter is obtained by dividing the total pore volume per mass of the sample obtained by measuring each equilibrium adsorption amount of nitrogen gas under each relative pressure under the liquid nitrogen temperature by the BET specific surface area. Refers to the thing.

<Average particle size>
The average particle size of the active material in the present embodiment is a particle at a point where the cumulative curve is 50% when the cumulative curve is obtained with the total product as 100% when the particle size distribution is measured using a particle size distribution measuring device. Refers to the diameter (ie, 50% diameter (Median diameter)). This average particle size can be measured using a commercially available laser diffraction type particle size distribution measuring device.

<Dispersity>
The degree of dispersion in this embodiment is a value obtained by a degree of dispersion evaluation test using a grain gauge specified in JIS K5600. That is, a sufficient amount of sample is poured into the tip of the deeper groove of the grain gauge having a groove having a desired depth according to the size of the grain, and the sample is slightly overflowed from the groove. Place the scraper so that the long side of the scraper is parallel to the width direction of the gauge and the cutting edge is in contact with the deep tip of the groove of the grain gauge, and hold the scraper so that it is on the surface of the gauge, with respect to the long side direction of the groove. At right angles, pull the surface of the gauge at a uniform speed to a groove depth of 0 for 1 to 2 seconds, and within 3 seconds after the end of pulling, shine light at an angle of 20 ° to 30 ° to observe. , Read the depth at which the grain appears in the groove of the grain gauge.

<Viscosity and TI value>
The viscosity (ηb) and TI value in the present embodiment are values obtained by the following methods, respectively. First, a stable viscosity (ηa) is obtained after measuring for 2 minutes or more under the conditions of a temperature of 25 ° C. and a shear rate of 2s- ¹ using an E-type viscometer. The viscosity (ηb) measured under the same conditions as above is obtained except that the shear rate is changed to 20s ^-1 . Using the viscosity value obtained above, the TI value is calculated by the formula TI value = ηa / ηb. When increasing the shear rate from 2s ^-1 to 20s ^-1 , the shear rate may be increased in one step, or the shear rate may be increased in multiple steps within the above range, and the viscosity at the shear rate may be appropriately obtained. You may let me.

<Method of identifying alkali metal compounds in electrodes>
The method for identifying the alkali metal compound contained in the positive electrode precursor is not particularly limited, and can be identified by, for example, SEM-EDX, Raman, and X-ray photoelectron spectroscopy (XPS) described below. For the identification of the alkali metal compound, it is preferable to identify by combining a plurality of analysis methods described below.

In ion chromatography, anions can be identified by analyzing the water after washing the positive electrode precursor with distilled water.

If the alkali metal compound cannot be identified by the above analysis method, ⁷ Li-solid NMR, XRD (X-ray diffraction), TOF-SIMS (time-of-flight secondary ion mass spectrometry), AES ( Alkali metal compounds can also be identified by using Auger electron spectroscopy), TPD / MS (heat generation gas mass spectrometry), DSC (differential scanning calorific value analysis) and the like.

(SEM-EDX)
The alkali metal compound and the positive electrode active material can be identified by oxygen mapping using an SEM-EDX image on the surface of the positive electrode precursor measured at an observation magnification of 1000 to 4000 times. As a measurement example of the SEM-EDX image, the acceleration voltage is 10 kV, the emission current is 1 μA, the number of measurement pixels is 256 × 256 pixels, and the number of integrations is 50. In order to prevent the sample from being charged, gold, platinum, osmium or the like can be surface-treated by a method such as vacuum deposition or sputtering. As the measurement conditions for the SEM-EDX image, it is preferable to adjust the brightness and contrast so that the brightness does not reach the maximum brightness and the average value of the brightness falls within the range of 40% to 60%. Particles containing 50% or more of bright areas that are binarized based on the average value of brightness with respect to the obtained oxygen mapping are designated as alkali metal compounds.

(Raman)
The alkali metal compound composed of carbonate ions and the positive electrode active material can be discriminated by Raman imaging of carbonate ions on the surface of the positive electrode precursor measured at an observation magnification of 1000 to 4000 times. As an example of measurement conditions, the excitation light is 532 nm, the excitation light intensity is 1%, the long operation of the objective lens is 50 times, the diffraction grating is 1800 gr / mm, the mapping method is point scanning (slit 65 mm, binning 5 pix), 1 mm step, The exposure time per point can be measured for 3 seconds, the number of integrations can be measured once, and the measurement can be performed under the condition of having a noise filter. For the measured Raman spectrum, a straight baseline is set in the range of 1071-1104 cm ^-1 , the area is calculated with a positive value from the baseline as the peak of carbonate ion, and the frequency is integrated. At this time, the noise component is added. The frequency for the bicarbonate peak area approximated by the Gaussian function is subtracted from the above frequency distribution of bicarbonate.

(XPS)
By analyzing the electronic state of the positive electrode precursor by XPS, the binding state of the compound contained in the positive electrode precursor can be determined.

As an example of measurement conditions, the X-ray source is monochromatic AlKα, the X-ray beam diameter is 100 μmφ (25 W, 15 kV), the path energy is narrow scan: 58.70 eV, there is charge neutralization, and the number of sweeps is narrow scan: 10 times. (Carbon, oxygen) 20 times (fluorine) 30 times (phosphorus) 40 times (alkali metal) 50 times (silicon), energy steps can be measured under the conditions of narrow scan: 0.25 eV.

It is preferable to clean the surface of the positive electrode precursor by sputtering before measuring XPS. As the sputtering conditions, for example, the surface of the positive electrode precursor can be cleaned under the condition of an accelerating voltage of 1.0 kV, 2 mm × 2 mm for 1 minute (1.25 nm / min in terms of SiO ₂ ).

About the obtained XPS spectrum
The peak of the binding energy of Li1s of 50 to 54 eV is LiO ₂ or Li-C bond,
Peaks of 55-60 eV are LiF, Li ₂ CO ₃ ,
Li _x PO _y F _z (in the formula, x, y, z are integers 1 to 6),
The peak of the binding energy of 285 eV of C1s is CC-bonded,
286eV peak is C—O bonded,
COO at the peak of 288eV,
The peak of 290 to 292 eV is CO ₃ ^2- , CF bond,
The peak of the binding energy of O1s of 527 to 530 eV is O ^2- (Li ₂ O),
Peaks of 531 to 532 eV are CO, CO ₃ , OH, PO _x (in the formula, x is an integer of 1 to 4), SiO _x (in the formula, x is an integer of 1 to 4),
The peak of 533 eV is CO, SiO _x (in the formula, x is an integer of 1 to 4),
The peak of the binding energy of F1s of 685 eV is LiF.
The peak of 687 eV C-F _bond, Li x _PO y _{F z} (wherein, x, y, z are an integer of 1 to 6), PF ₆ ^-,
Furthermore, regarding the binding energy of P2p,
The peak of 133 eV is PO _x (in the formula, x is an integer of 1 to 4),
Peaks of 134 to 136 eV are PF _x (in the formula, x is an integer of 1 to 6),
The peak of the binding energy 99eV of Si2p is Si, Silicide,
Peaks of 101-107 eV are Si _x O _y (in the formula, x and y are arbitrary integers)
Can be attributed as.

When the peaks of the obtained spectrum overlap, it is preferable to separate the peaks assuming a Gaussian function or a Lorentz function and assign the spectra. The existing alkali metal compound can be identified from the measurement result of the electronic state and the result of the existing element ratio obtained above.

(Ion chromatography)
By analyzing the distilled water washing solution of the positive electrode precursor by ion chromatography, the anion species eluted in water can be identified. As the column to be used, an ion exchange type, an ion exclusion type, and a reverse phase ion pair type can be used. As the detector, an electric conductivity detector, an ultraviolet visible absorptiometry detector, an electrochemical detector, etc. can be used, and a suppressor method in which a suppressor is installed in front of the detector, or electricity without a suppressor. A non-suppressor method using a solution having low conductivity as an eluent can be used. Mass spectrometers and charged particle detection can also be measured in combination with detectors.

The retention time of the sample is constant for each ion species component if conditions such as the column to be used and the eluent are determined, and the magnitude of the peak response differs for each ion species but is proportional to the concentration. By measuring in advance a standard solution having a known concentration that ensures traceability, it is possible to qualitatively and quantify the ionic species components.

<Calculation method of alkali metal compound X>
The method for quantifying the alkali metal compound contained in the positive electrode precursor is described below. The positive electrode precursor is washed with distilled water, and the alkali metal compound can be quantified from the change in the weight of the positive electrode before and after washing with distilled water. Although area measurement is the cathode precursor is not particularly limited, it is preferably, more preferably 25 cm ² or more 150 cm ² or less from the viewpoint of reducing the variation in measurement is 5 cm ² or more 200 cm ² or less. If the area is 5 cm ² or more, the reproducibility of measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent. The upper and lower limits of the area range of the positive electrode precursor to be measured can be arbitrarily combined.

Hereinafter, a method for quantifying an alkali metal compound in the positive electrode active material layer of the positive electrode precursor will be described. The weight of the cut positive electrode precursor is measured and set to M ₀ [g]. Subsequently, in an environment of 25 ° C., the positive electrode is sufficiently immersed in distilled water 100 times the weight of the positive electrode precursor (100 M ₀ [g]) for 3 days or more, and the alkali metal compound is eluted in the water. At this time, it is preferable to take measures such as covering the container so that the distilled water does not volatilize. After soaking for 3 days or more, the positive electrode precursor is taken out from the distilled water (when the above ion chromatography is measured, the amount of the liquid is adjusted so that the amount of the distilled water becomes 100M ₀ [g]), and vacuum is vacuumed. dry. As the conditions for vacuum drying, for example, it is preferable that the residual water content in the positive electrode precursor is 1% by mass or less in the range of temperature: 100 to 200 ° C., pressure: 0 to 10 kPa, and time: 5 to 20 hours. The residual amount of water can be quantified by the Karl Fischer method. The weight of the positive electrode precursor after vacuum drying is set to M ₁ [g], and then, in order to measure the weight of the current collector of the obtained positive electrode precursor, a spatula, a brush, a brush, or the like is used on the current collector. Remove the positive electrode active material layer of. Assuming that the weight of the obtained positive electrode current collector is M ₂ [g], the weight ratio X [mass%] of the alkali metal compound contained in the active material layer of the positive electrode precursor can be calculated by the formula (3). ..
X = 100 × (M _0- M ₁ ) / (M _0- M ₂ ) Equation (3)

<Method for quantifying alkali metal elements ICP-MS>
The positive electrode precursor is acid-decomposed with a strong acid such as concentrated nitric acid, concentrated hydrochloric acid, and aqua regia, and the obtained solution is diluted with pure water to an acid concentration of 2% to 3%. As for acid decomposition, it can be decomposed by heating and pressurizing as appropriate. The obtained diluent is analyzed by ICP-MS, and it is preferable to add a known amount of elements as an internal standard at this time. When the alkali metal element to be measured exceeds the upper limit concentration for measurement, it is preferable to further dilute the diluted solution while maintaining the acid concentration. With respect to the obtained measurement results, each element can be quantified based on a calibration curve prepared in advance using a standard solution for chemical analysis.

Hereinafter, embodiments of the present invention will be specifically described with reference to Examples and Comparative Examples, however, the present invention is not limited to the following Examples and Comparative Examples.

<Preparation of positive electrode active material>
[Preparation of activated carbon 1]
The crushed coconut shell carbide was carbonized in nitrogen at 500 ° C. for 3 hours in a small carbonization furnace to obtain carbonized material. The obtained carbide was put into an activation furnace, and 1 kg / h of steam was introduced into the above-mentioned activation furnace in a state of being heated in the preheating furnace, and the temperature was raised to 900 ° C. over 8 hours for activation. The activated carbon was taken out and cooled in a nitrogen atmosphere to obtain activated activated carbon. The obtained activated carbon was washed with water for 10 hours and then drained. Activated carbon 1 was obtained by drying in an electric dryer maintained at 115 ° C. for 10 hours and then pulverizing with a ball mill for 1 hour.

As a result of measuring the average particle size of this activated carbon 1 using a laser diffraction type particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation, it was 4.2 μm. The pore distribution was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 2360 m ² / g, the mesopore amount (V ₁ ) was 0.52 cc / g, the micro hole amount (V ₂ ) was 0.88 cc / g, and V ₁ / V ₂ = 0.59. there were.

[Preparation of activated carbon 2]
The phenol resin was carbonized in a firing furnace at 580 ° C. for 2 hours in a nitrogen atmosphere, then pulverized with a ball mill and classified to obtain a carbide having an average particle size of 6.8 μm. This carbide and KOH were mixed at a mass ratio of 1: 5 and activated by heating in a firing furnace at 800 ° C. for 1 hour in a nitrogen atmosphere to obtain activated activated carbon. The obtained activated carbon was washed with stirring in dilute hydrochloric acid adjusted to a concentration of 2 mol / L for 1 hour, then boiled and washed with distilled water until it became stable between pH 5 and 6, and dried to obtain activated carbon 2. ..

The average particle size of this activated carbon 2 was 6.7 μm as a result of measuring the average particle size using a laser diffraction type particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation. The pore distribution was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 3328 m ² / g, the mesopore amount (V ₁ ) was 1.55 cc / g, the micro hole amount (V ₂ ) was 2.01 cc / g, and V ₁ / V ₂ = 0.77. there were.

<Manufacturing of positive electrode precursor>

[Manufacturing of positive electrode precursor (composition a)]
Using any one of the activated carbons 1 and 2 obtained above as the positive electrode active material, a positive electrode precursor (composition a) was produced by the following method.

Any one of activated carbons 1 and 2 is 55.5 parts by mass, lithium carbonate or the like having an average particle size shown in Table 1 is 32.0 parts by mass, and Ketjen Black is 3.0 parts by mass as an alkali metal compound. In addition, NMP (N-methylpyrrolidone) was premixed with a planetary ball mill manufactured by Frisch. To the mixture, 1.5 parts by mass of PVP (polyvinylidene fluoride), 8.0 parts by mass of PVdF (vinylidene fluoride), and NMP (N-methylpyrrolidone) were added, and a thin film swirling high-speed mixer manufactured by PRIMIX Corporation was added. A coating liquid was obtained by dispersing using a fill mix under the condition of a peripheral speed of 17.0 m / s. The above coating liquid is applied to one or both sides of an aluminum foil having a thickness of 15 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, dried at a drying temperature of 100 ° C., and a positive electrode precursor. A body (composition a) was obtained. The obtained positive electrode precursor was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the pressed portion of 25 ° C. to obtain a positive electrode precursor (composition a).

[Manufacturing of positive electrode precursor (composition b)]
Any one of activated carbons 1 and 2 is 64.4 parts by mass, lithium carbonate is 21.1 parts by mass, Ketjen Black is 3.5 parts by mass, PVP is 1.7 parts by mass, and PVdF is 9.3 parts by mass. A positive electrode precursor (composition b) was obtained in the same manner as the positive electrode precursor (composition a) except for the portion.

[Manufacturing of positive electrode precursor (composition c)]
Any one of activated carbons 1 and 2 is 71.7 parts by mass, lithium carbonate is 12.2 parts by mass, Ketjen Black is 3.9 parts by mass, PVP is 1.9 parts by mass, and PVdF is 10.3 parts by mass. A positive electrode precursor (composition c) was obtained in the same manner as the positive electrode precursor (composition a) except for the portion.

[Manufacturing of positive electrode precursor (composition d)]
Any one of activated carbons 1 and 2 is 74.4 parts by mass, lithium carbonate is 8.9 parts by mass, Ketjen Black is 4.0 parts by mass, PVP is 2.0 parts by mass, and PVdF is 10.7 parts by mass. A positive electrode precursor (composition d) was obtained in the same manner as the positive electrode precursor (composition a) except for the portion.

[Manufacturing of positive electrode precursor (composition e)]
Any one of activated carbons 1 and 2 is 76.5 parts by mass, lithium carbonate is 6.3 parts by mass, Ketjen Black is 4.1 parts by mass, PVP is 2.1 parts by mass, and PVdF is 11.0 parts by mass. A positive electrode precursor (composition e) was obtained in the same manner as the positive electrode precursor (composition a) except for the portion.

[Manufacturing of positive electrode precursor (composition f)]
Any one of activated carbons 1 and 2 is 43.1 parts by mass, lithium carbonate is 47.2 parts by mass, Ketjen Black is 2.3 parts by mass, PVP is 1.2 parts by mass, and PVdF is 6.2 parts by mass. A positive electrode precursor (composition f) was obtained in the same manner as the positive electrode precursor (composition a) except for the portion.

[Manufacturing of positive electrode precursor (composition g)]
Any one of activated carbons 1 and 2 is 78.5 parts by mass, lithium carbonate is 3.9 parts by mass, Ketjen Black is 4.2 parts by mass, PVP is 2.1 parts by mass, and PVdF is 11.3 parts by mass. A positive electrode precursor (composition g) was obtained in the same manner as the positive electrode precursor (composition a) except that the portion was used.

[Manufacturing of positive electrode precursor (composition h)]
Any one of activated carbons 1 and 2 is 30.8 parts by mass, lithium carbonate is 62.3 parts by mass, Ketjen Black is 1.7 parts by mass, PVP is 0.8 parts by mass, and PVdF is 4.4 parts by mass. A positive electrode precursor (composition h) was obtained in the same manner as the positive electrode precursor (composition a) except for the portion.
<< Example 1 >>
<Manufacturing of positive electrode precursor>
Using activated carbon 2, a double-sided positive electrode precursor 1 and a single-sided positive electrode precursor 1 were obtained with the above composition a. The thickness of the positive electrode active material layer of the obtained double-sided and single-sided positive electrode precursor 1 was measured at any 10 locations of the double-sided and single-sided positive electrode precursor 1 using a film thickness meter Liner Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. It was obtained by subtracting the thickness of the aluminum foil from the average value of the thickness. As a result, the thickness of the positive electrode active material layer of the double-sided and single-sided positive electrode precursor 1 was 60 μm per one side.

<Calculation of X>
The double-sided positive electrode precursor 1 was cut into a size of 10 cm × 5 cm to obtain a sample 1, and the weight M ₀ was measured. The lithium carbonate in the sample 1 was eluted into the distilled water by impregnating the sample 1 with 31.0 g of distilled water and maintaining the sample 1 in an environment of 25 ° C. for 3 days. Sample 1 was taken out and vacuum dried at 150 ° C. and 3 kPa for 12 hours. The weight M ₁ at this time was measured. The active material layer on the positive electrode current collector was removed using a spatula, a brush, and a brush, and the weight M ₂ of the positive electrode current collector was measured. X was calculated from the above M ₀ , M ₁ and M _{2 according} to the above equation (3). The results obtained are shown in Table 1.

<A ₁ ,A ₂ OyobiA ₃ Nosanshutsu_>
[Sample preparation]
A small piece of 1 cm × 1 cm was cut out from the double-sided positive electrode precursor 1, and the surface was coated with gold by sputtering in a vacuum of 10 Pa.

[Surface SEM and EDX measurement]
For the prepared sample, SEM and EDX on the surface of the positive electrode precursor were measured under atmospheric exposure. The measurement conditions are described below.
(SEM-EDX measurement conditions)
-Measuring device: Electron emission scanning electron microscope FE-SEM S-4700 manufactured by Hitachi High-Technology
・ Acceleration voltage: 10kV
・ Emission current: 1 μA
・ Measurement magnification: 2000 times ・ Electron beam incident angle: 90 °
・ X-ray extraction angle: 30 °
・ Dead time: 15%
-Mapping elements: C, O, F
-Number of measurement pixels: 256 x 256 pixels-Measurement time: 60 sec.
-Number of integrations: 50 times-The brightness and contrast were adjusted so that there were no pixels that reached the maximum brightness and the average value of the brightness was within the range of 40% to 60%.
(Analysis of SEM-EDX)
Images obtained from the measured surface SEM and EDX were image-analyzed by the method described above using image analysis software (ImageJ) to calculate A ₁ and A ₂ . The results are shown in Table 1.

[Cross-section SEM and EDX measurement]
A small piece of 1 cm × 1 cm was cut out from the double-sided positive electrode precursor 1, and using SM-09020CP manufactured by JEOL Ltd., using argon gas, the acceleration voltage was 4 kV, and the beam diameter was 500 μm in the plane direction of the double-sided positive electrode precursor 1. A vertical cross section was made. Cross sections SEM and EDX were measured by the method described above.

The images obtained from the measured cross-sectional SEM and EDX, were calculated _{A 3} and _A 3 / X by image analysis in the manner described above using an image analysis software (ImageJ). The results are shown in Table 1.

<Preparation of negative electrode active material>
Made of stainless steel containing 150 g of commercially available artificial graphite with a BET specific surface area of 3.1 m ² / g and an average particle size of 4.8 μm in a stainless steel mesh cage and 15 g of coal-based pitch (softening point: 50 ° C.). They were placed on a bat and both were installed in an electric furnace (effective size in the furnace 300 mm × 300 mm × 300 mm). The temperature was raised to 1000 ° C. over 8 hours under a nitrogen atmosphere, and the temperature was maintained at the same temperature for 4 hours to cause a thermal reaction between the two to obtain a composite carbon material 1. Subsequently, after cooling to 60 ° C. by natural cooling, the composite carbon material 1 was taken out from the furnace.

For the obtained composite carbon material 1, the average particle size and the BET specific surface area were measured by the same method as described above. As a result, the average particle size was 4.9 μm and the BET specific surface area was 6.1 m ² / g. The mass ratio of the carbonaceous material derived from the carbonaceous pitch to artificial graphite was 2%.

<Manufacturing of negative electrode>

Using the composite carbon material 1 as the negative electrode active material, the negative electrode 1 was manufactured as follows.
80 parts by mass of composite carbon material 1, 8 parts by mass of acetylene black, 12 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed, and the mixture is a thin film swirl type manufactured by PRIMIX Corporation. A coating liquid was obtained by dispersing under the condition of a peripheral speed of 15 m / s using a high-speed mixer fill mix. The viscosity (ηb) and TI value of the obtained coating liquid were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,798 mPa · s, and the TI value was 2.7. The above coating liquid was applied to both sides of an electrolytic copper foil having a thickness of 10 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, and dried at a drying temperature of 85 ° C. to obtain a negative electrode 1. .. The obtained negative electrode 1 was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the pressed portion of 25 ° C. The thickness of the negative electrode active material layer of the negative electrode 1 obtained above was measured from the average value of the thickness measured at any 10 points of the negative electrode 1 using a film thickness meter Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. It was calculated by subtracting the thickness of the foil. As a result, the thickness of the negative electrode active material layer of the negative electrode 1 was 30 μm per one side.

<Preparation of non-aqueous electrolyte solution>
As the organic solvent, a mixed solvent of ethylene carbonate (EC): methyl ethyl carbonate (EMC) = 33: 67 (volume ratio) was used, and LiN (SO ₂ F) ₂ and LiPF ₆ were added to the obtained non-aqueous electrolyte solution. Each electrolyte salt is dissolved in a mixed solvent so that the concentration ratio is 75:25 (molar ratio) and the sum of the concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ is 1.2 mol / L. A non-aqueous electrolyte solution was obtained.

The concentrations of LiN (SO ₂ F) ₂ and LiPF _{6 in} the obtained non-aqueous electrolyte solution were 0.9 mol / L and 0.3 mol / L, respectively.

<Manufacturing of non-aqueous hybrid capacitors>
[Assembly and drying of power storage element]
The obtained double-sided positive electrode precursor 1, double-sided negative electrode 1, and single-sided positive electrode precursor 1 were cut into 10 cm × 10 cm (100 cm ² ). A single-sided positive electrode precursor 1 is used for the uppermost surface and the lowermost surface, 21 double-sided negative electrode 1s and 20 double-sided positive electrode precursors 1 are used, and a microporous film having a thickness of 15 μm is used between the negative electrode and the positive electrode precursor. Laminated with a separator in between. The negative electrode terminal and the positive electrode terminal were connected to the negative electrode and the positive electrode precursor by ultrasonic welding, respectively, to form an electrode laminate. This electrode laminate was vacuum dried at a temperature of 80 ° C. and a pressure of 50 Pa under the conditions of a drying time of 60 hr. The dried electrode laminate is housed in an exterior body made of aluminum laminate packaging material under a dry environment with a dew point of −45 ° C., and the electrode terminal portion and the bottom exterior body are placed at a temperature of 180 ° C. and a sealing time. Heat sealing was performed under the conditions of 20 sec and a sealing pressure of 1.0 MPa.

[Liquid injection, impregnation, sealing of power storage elements]
Approximately 80 g of the non-aqueous electrolyte solution is injected under atmospheric pressure into the electrode laminate housed in the aluminum laminate packaging material in a dry air environment with a temperature of 25 ° C and a dew point of -40 ° C or less, and pre-doped treatment is performed. The previous non-aqueous hybrid capacitor was formed. Subsequently, the non-aqueous hybrid capacitor was placed in the decompression chamber, the pressure was reduced from normal pressure to −87 kPa, the pressure was returned to atmospheric pressure, and the mixture was allowed to stand for 5 minutes. After reducing the pressure from normal pressure to −87 kPa, the operation of returning to atmospheric pressure was repeated four times, and then the power storage element was allowed to stand for 15 minutes. After reducing the pressure from normal pressure to -91 kPa, the pressure was returned to atmospheric pressure. Similarly, the operation of reducing the pressure and returning to the atmospheric pressure was repeated 7 times in total. (The pressure was reduced from normal pressure to -95, -96, -97, -81, -97, -97, and -97 kPa, respectively). By the above procedure, the electrode laminate was impregnated with the non-aqueous electrolyte solution.

The exterior body containing the electrode laminate impregnated with the non-aqueous electrolyte solution is placed in a decompression sealing machine, and the pressure is reduced to -95 kPa, and the aluminum laminate is sealed at 180 ° C. for 10 seconds at a pressure of 0.1 MPa. The packaging material was sealed to obtain a non-aqueous hybrid capacitor.

[Pre-dope]
The obtained non-aqueous hybrid capacitor is constantly charged using a charging / discharging device (TOSCAT-3100U) manufactured by Toyo Systems Co., Ltd. in a 25 ° C environment at a current value of 0.5 A until a voltage of 4.5 V is reached. After that, the initial charge was continuously performed by a method of continuing 4.5 V constant voltage charging for 2 hours, and the negative electrode was pre-doped.

[aging]
After pre-doping the non-aqueous hybrid capacitor in a 25 ° C environment, constant current discharge is performed at 0.5 A until the voltage reaches 3.0 V, and then 3.0 V constant current discharge is performed for 1 hour to increase the voltage to 3.0 V. Adjusted to. Subsequently, the non-aqueous hybrid capacitor was stored in a constant temperature bath at 60 ° C. for 12 hours.

[gas releasing]
A part of the aluminum laminate packaging material of the non-aqueous hybrid capacitor after aging was opened in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. Subsequently, the non-aqueous hybrid capacitor was placed in the decompression chamber, and the pressure was reduced from atmospheric pressure to -80 kPa for 3 minutes using a diaphragm pump (N816.3KT.45.18) manufactured by KNF. The operation of returning to atmospheric pressure was repeated three times in total. A non-aqueous hybrid capacitor was placed in a vacuum sealing machine, the pressure was reduced to −90 kPa, and then the aluminum laminate packaging material was sealed by sealing at 200 ° C. for 10 seconds at a pressure of 0.1 MPa.

Through the above procedure, a non-aqueous hybrid capacitor was completed.

<Evaluation of non-aqueous hybrid capacitors>
[Measurement of capacitance and Ra / F]
With respect to the obtained non-aqueous hybrid capacitor, the capacitance F and 25 were obtained by the above-mentioned method using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited in a constant temperature bath set at 25 ° C. The internal resistance Ra at ° C. was calculated, and Ra · F and energy density E / V were obtained. The results obtained are shown in Table 1.

<< Examples 2 to 21 and 24 to 27, Reference Examples 22 and 23, and Comparative Examples 1 to 8 >>
Example 2 is the same as in Example 1 except that the positive electrode active material of the positive electrode precursor, the type of alkali metal compound, the compounding ratio and the average particle size thereof, the composition, and the presence or absence of premixing are as shown in Table 1, respectively. ~ 21 and 24 to 27, Reference Examples 22 and 23, and positive electrode precursors and non-aqueous hybrid capacitors of Comparative Examples 1 to 8, respectively, were prepared and evaluated in various ways. The obtained evaluation results are shown in Table 1.

<< Comparative Example 9 >>
<Manufacturing of positive electrode precursor (composition i)>
Activated carbon 2 is 87.5 parts by mass, Ketchen Black is 3.0 parts by mass, PVP (polyvinylpyrrolidone) is 1.5 parts by mass, PVdF (polyvinylidene fluoride) is 8.0 parts by mass, and NMP (N-). Methylpyrrolidone) was mixed, and the mixture was dispersed under the condition of a peripheral speed of 17 m / s using a thin film swirl type high-speed mixer fill mix manufactured by PRIMIX to obtain a coating liquid. The above coating liquid is applied to one or both sides of an aluminum foil having a thickness of 15 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, dried at a drying temperature of 100 ° C., and a positive electrode precursor (positive electrode precursor). Composition i) was obtained. The obtained positive electrode precursor was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the pressed portion of 25 ° C. The obtained positive electrode precursor (composition i) was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Manufacturing and evaluation of non-aqueous hybrid capacitors>
Same as in Example 1 except that the obtained positive electrode precursor (composition i) and a negative electrode in which a metallic lithium foil corresponding to 211 mAh / g per unit mass of the negative electrode active material is attached to the surface of the negative electrode active material layer of the negative electrode 1 are used. Then, the non-aqueous hybrid capacitor was assembled, injected, impregnated, and sealed.

Next, as a pre-dope, the non-aqueous hybrid capacitor obtained above was stored in a constant temperature bath at an environmental temperature of 45 ° C. for 72 hours, and metallic lithium was ionized to dope the negative electrode 1. The obtained non-aqueous hybrid capacitor was aged and degassed in the same manner as in Example 1 to produce a non-aqueous hybrid capacitor, which was evaluated. The results are shown in Table 1.
<< Comparative Example 10 >>
The positive electrode precursor and the non-aqueous hybrid capacitor of Comparative Example 10 were prepared in the same manner as in Comparative Example 9 except that the positive electrode active material was activated carbon 1, and various evaluations were performed. The results are shown in Table 1.

As described above, the alkali metal compound contained in the positive electrode precursor is decomposed, and the alkali metal ion that can participate in charging and discharging is pre-doped into the negative electrode or released into the electrolytic solution, thereby causing a non-aqueous hybrid capacitor. Charging and discharging will proceed.

As can be seen from the comparison of Examples 1 to 21 and 24 to 27, Reference Examples 22 and 23, and Comparative Examples 1 to 10, the weight ratio X [mass%] of the alkali metal compound of the positive electrode precursor is 5 ≦ X ≦ 50. If the area overlap ratio A ₁ [%] of the carbon mapping with respect to the oxygen mapping obtained by SEM-EDX on the surface of the positive electrode precursor is 30 ≦ A ₁ ≦ 90, the positive electrode precursor is incorporated into the non-aqueous hybrid capacitor. At that time, it can be seen that a non-aqueous hybrid capacitor having characteristics of low Ra / F (low internal resistance, that is, high input / output characteristics) and high energy density E / V can be obtained.

Although not limited to the theory, when X is 5 or more, the capacitance F is increased because sufficient alkali metal ions that can participate in charging / discharging are secured when the positive electrode precursor is incorporated into the non-aqueous hybrid capacitor. It is considered that a non-aqueous hybrid capacitor showing high energy density and high energy density can be obtained. Further, it is considered that a non-aqueous hybrid capacitor exhibiting high input / output characteristics can be obtained by forming appropriate pores remaining in the positive electrode after the alkali metal compound is oxidatively decomposed. When X is 50 or less, the electron conductivity in the positive electrode precursor is enhanced, so that the decomposition of the alkali metal compound is promoted, so that predoping proceeds sufficiently and the ratio of the positive electrode active material in the positive electrode is sufficiently secured. Therefore, it is considered that a non-aqueous hybrid capacitor with high energy density can be obtained.

When A ₁ is 30 or more, pre-doping is promoted in order to secure electron conductivity between the alkali metal compound and the conductive member such as the positive electrode active material and / or the conductive filler, and the positive electrode is imparted with porosity. It is considered that a non-aqueous hybrid capacitor with high input / output can be obtained. If A ₁ is 90 or less, it is presumed that pre-doping is promoted because the diffusion of alkali metal ions in the electrolytic solution is promoted.

The positive electrode precursor of the present invention can be suitably used as a positive electrode precursor of a non-aqueous hybrid capacitor in, for example, in the field of hybrid drive systems for automobiles, assist applications for instantaneous power peaks, and the like. The non-aqueous hybrid capacitor of the present invention is preferable because the effect of the present invention is maximized when applied as a lithium ion capacitor.

Claims (9)

It has an alkali metal compound other than the positive electrode active material, a positive electrode current collector, and a positive electrode active material layer on one side or both sides of the positive electrode current collector, and the positive electrode active material layer contains a positive electrode active material containing a carbon material. Containing, positive electrode precursor,
The alkali metal compound is at least one selected from the group consisting of lithium carbonate, sodium carbonate, and potassium carbonate.
When the weight ratio of the alkali metal compound is X mass% based on the mass of the positive electrode precursor excluding the positive electrode current collector, 5 ≦ X ≦ 50.
In the element mapping obtained by SEM-EDX on the surface of the positive electrode precursor, when the area overlap ratio of the carbon mapping with respect to the oxygen mapping binarized based on the average value of the brightness is A ₁ %, 30 ≤ A ₁ ≤ 90, positive electrode precursor for non-aqueous hybrid capacitors . In the element mapping obtained by SEM-EDX on the surface of the positive electrode precursor, when the area overlap ratio of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness is A ₂ %, 1 ≦ A ₂ ≦ The positive electrode precursor for a non-aqueous hybrid capacitor according to claim 1, which is 50. In the oxygen mapping obtained by SEM-EDX of the BIB-processed positive electrode precursor cross section, when the area of the oxygen mapping binarized based on the average value of brightness is A ₃ %, 5 ≤ A ₃ ≤ 60. The positive electrode precursor for a non-aqueous hybrid capacitor according to claim 1 or 2, which is present and has 0.5 ≦ A _{3 /} X ≦ 2.0. The positive electrode precursor for a non-aqueous hybrid capacitor according to any one of claims 1 to 3, wherein the carbon material of the positive electrode active material is activated carbon. The activated carbon has a mesopore amount derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method. ₁ (Cc / g), V is the amount of micropores derived from pores with a diameter of less than 20 Å calculated by the MP method. ₂ When (cc / g), 0.3 <V ₁ ≤0.8 and 0.5≤V ₂ Satisfying ≤1.0 and measuring the specific surface area by the BET method is 1,500 m. ² / G or more 3,000m ² The positive electrode precursor for a non-aqueous hybrid capacitor according to claim 4, which is / g or less. The activated carbon is derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method.
Meso hole amount V ₁ (Cc / g), V is the amount of micropores derived from pores with a diameter of less than 20 Å calculated by the MP method. ₂ When (cc / g), 0.8 <V ₁ ≤2.5 and 0.8 <V ₂ Satisfying ≤3.0 and measuring the specific surface area by the BET method is 2,300 m. ² / G or more 4,000m ² The positive electrode precursor for a non-aqueous hybrid capacitor according to claim 4, which is / g or less. The positive electrode precursor for a non-aqueous hybrid capacitor according to any one of claims 4 to 6, wherein the activated carbon has an average particle size of 2 to 20 μm. The positive electrode precursor and the negative electrode according to any one of claims 1 to 7 are an electrode laminate for a non-aqueous hybrid capacitor having a structure in which the positive electrode precursor and the negative electrode are laminated via a separator, and the negative electrode is a negative electrode collection. The negative electrode active material has a negative electrode active material layer on one side or both sides of the negative electrode current collector, and the negative electrode active material layer contains a negative electrode active material capable of storing and releasing alkali metal ions. , An electrode laminate for a non-aqueous hybrid capacitor, which contains a composite carbon material of artificial graphite or natural graphite and a carbonaceous material obtained by heat-treating a carbonaceous material precursor. The electrode wound body for a non-aqueous hybrid capacitor having a structure in which the positive electrode precursor and the negative electrode according to any one of claims 1 to 7 are laminated and wound via a separator, and the negative electrode Has a negative electrode current collector and a negative electrode active material layer on one side or both sides of the negative electrode current collector, and the negative electrode active material layer contains a negative electrode active material capable of storing and releasing alkali metal ions. The negative electrode active material is an electrode wound body for a non-aqueous hybrid capacitor containing a composite carbon material of artificial graphite or natural graphite and a carbonaceous material obtained by heat-treating a carbonaceous material precursor.