JP6487841B2 - Power storage device - Google Patents

Description

  The present invention relates to a storage device having high energy density, high output, and durability.

In recent years, a storage device called a hybrid capacitor, in which storage principles of a lithium ion secondary battery and an electric double layer capacitor are combined, has attracted attention.
In such a hybrid capacitor, a carbon material capable of absorbing and desorbing lithium ions is made to occlude and support lithium ions in advance (hereinafter also referred to as doping) by a chemical method or an electrochemical method in advance to lower the negative electrode potential. Thus, a storage device capable of obtaining a high energy density has been proposed (see, for example, Patent Document 1). In addition, the cell capacity at the time of discharging to a half voltage from the fully charged state is a [mAh], and the capacity at the time of discharging the charged negative electrode to 1.5 V [Li / Li ⁺ ] is completely negative capacity b [ An organic electrolyte capacitor (for example, patent document) in which the ratio of the positive electrode active material to the negative electrode active material is defined so as to satisfy 0.05 ≦ a / b ≦ 0.3 when mAh] is satisfied. 2) etc. are also proposed.

However, when high output is achieved as in Patent Document 2, higher energy density is achieved than in the case of an electric double layer capacitor, but in a general lithium ion capacitor, the energy density is low. .
When the weight of the positive electrode active material is increased as in Patent Document 1, a lithium ion capacitor with high energy density can be obtained. As described above, when the weight of the positive electrode active material is increased, the resistance at the end of discharge increases, so that the rate characteristics deteriorate, and the cycle characteristics deteriorate as compared with the conventional capacitor. The cause is that the load on the negative electrode is high, and it is considered that when charge and discharge are repeated, the decrease in cell capacity is quickened by the consumption of lithium ions in the negative electrode active material. That is, high power and high energy density are in a trade-off relationship, and it has been difficult to maintain a good balance of the performance of the storage device.

Japanese Patent No. 4015 993 International Publication WO 2005/031773 Brochure

  The present invention has been made based on the circumstances as described above, and an object thereof is to provide an electricity storage device having high energy density, high output, and durability.

The inventors of the present invention have conducted researches to achieve the above object, and have arrived at the present invention having the following constitution as a summary.
(1) An electrode unit in which a positive electrode having a positive electrode active material layer formed on a positive electrode current collector and a negative electrode having a negative electrode active material layer formed on a negative electrode current collector are alternately stacked via a separator. And an electrolytic solution comprising an aprotic organic solvent solution of a lithium salt,
The capacity when discharged to half the voltage of full charge from the state of full charge of the storage device for 0.75 to 1.25 hours is the cell capacity a (mAh), and the state of full charge of the storage device The capacity of the negative electrode is discharged until the negative electrode potential reaches 1.5 V (Li / Li ⁺ ), and the capacity is the complete negative electrode capacity b (mAh). Assuming that the capacity at the time of (CCCV charging) is the total negative electrode charging capacity c (mAh), 0.35 ≦ a / b ≦ 0.95, 0.55 ≦ b / c ≦ 1.00, 0.35 ≦ It meets a / c ≦ 0.55, wherein the electrode density of the positive electrode active material layer is ^{0.54g / cm 3 ~0.7g / cm 3} , and the electrode weight per unit area of the positive electrode active material layer is 70 g ^{/ m} 2 ~ It is 110 g / m < ² >, The electrical storage device characterized by the above-mentioned.

(2) The electricity storage device according to (1), wherein the negative electrode active material layer contains graphite-based particles.
(3) The electricity storage device according to (1) or (2) above, wherein the positive electrode active material layer contains activated carbon.
(4) The electricity storage device according to (1) to (3), wherein the thickness of the separator is 5 μm to 20 μm.
(5) The electricity storage device according to any one of (1) to (4), wherein the positive electrode current collector and / or the negative electrode current collector has a through hole.
(6) The electricity storage device according to any one of (1) to (5), wherein the electrode unit is a stacked type or a wound type.
(7) The electricity storage device according to any one of (1) to (6), wherein the negative electrode is a negative electrode doped with lithium ions in advance.
(8) The electricity storage device according to any one of the above (1) to (7), which is a lithium ion capacitor.
(9) The electricity storage device according to (8), which has an energy density of 31.5 Wh / L or more.

  According to the storage device of the present invention, for example, a lithium ion capacitor or lithium ion secondary battery, high durability can be maintained without deterioration even when the load on the negative electrode is increased, and high energy density can be obtained and high output. Characteristics are obtained.

The electricity storage device of the present invention basically has an electrode unit in which an anode and an anode are alternately stacked or wound via a separator in an outer container. The outer container may be cylindrical, square, laminate, or the like as appropriate, and is not particularly limited.
In the electricity storage device of the present invention, “positive electrode” means an electrode to which current flows out during discharge and into which current flows during charge, and “negative electrode” means current flows during discharge. Mean the pole from which the current flows out during charging.

  In the present specification, “dope” means storage, adsorption or insertion, and refers to a phenomenon in which at least one of lithium ions and anions enters the positive electrode active material, or a phenomenon in which lithium ions enter the negative electrode active material. The term "de-doping" refers to desorption and release, and refers to a phenomenon in which lithium ions or anions are desorbed from the positive electrode active material or a phenomenon in which lithium ions are desorbed from the negative electrode active material.

In the electricity storage device of the present invention, at least one of the negative electrode and the positive electrode is preferably doped in advance with lithium ions. More preferably, the negative electrode is pre-doped with lithium ions.
As a method of pre-doping lithium ion to at least one of the negative electrode and the positive electrode, for example, metal lithium etc. is disposed as a lithium electrode in a storage device, and lithium is obtained by electrochemical contact between at least one of the negative electrode and the positive electrode A method of doping ions is used.

  In the electricity storage device of the present invention, at least one of the negative electrode and the positive electrode can be uniformly doped with lithium ions also by disposing the lithium electrode locally in the cell and making electrochemical contact.

  The electricity storage device of the present invention is, for example, a positive electrode in which a positive electrode current collector having a hole penetrating through the front and back surfaces, a positive electrode active material layer formed, a first separator, and a negative electrode current collector having holes penetrating through the front and back surfaces. The negative electrode on which the negative electrode active material layer is formed and the second separator are sequentially wound or stacked, and at least one lithium electrode is disposed in the surplus portion of the first separator so as not to contact the positive electrode. The lithium electrode is shorted to form an electrode unit. After the electrode unit is enclosed in a rectangular, cylindrical or laminate type outer container, by filling the electrolyte solution, doping of lithium ions from the lithium electrode is started, and lithium ions are doped in the negative electrode active material layer be able to. Thus, a power storage device is configured.

  Although a lithium ion capacitor and a lithium ion secondary battery can be mentioned as a specific example of the electrical storage device of this invention, Especially, a lithium ion capacitor is preferable.

In the present invention, the lithium ion capacitor means an electricity storage device containing lithium ions in which the positive electrode is a polarizable electrode and the negative electrode is a nonpolarizable electrode.
As a positive electrode material of a lithium ion capacitor, a material having a large specific surface area such as activated carbon or polyacene is preferably used, and as a material of the negative electrode, core particles made of graphite, non-graphitizable carbon, natural graphite are derived from tar or pitch And a heat-treated material of an aromatic condensation polymer coated with the graphitized substance of the present invention and having an atomic ratio of hydrogen atoms to carbon atoms (hydrogen atom / carbon atom) of 0.50 to 0.2. Carbonaceous materials such as polyacene-based organic semiconductor (PAS) having a polyacene-based framework structure of 05, metal oxides such as lithium titanate, and metal alloys such as silicon and tin are preferably used. As a lithium ion capacitor, it is preferable that a negative electrode is a negative electrode which doped lithium ion previously. The lithium ion capacitor in which the negative electrode is a negative electrode doped with lithium ions in advance is preferable because the use of the storage device can be started from the charging operation. The energy density of the lithium ion capacitor of the present invention is preferably 31.5 Wh / L or more, more preferably 33 Wh / L or more.

  In the present invention, the lithium ion secondary battery means an electricity storage device containing lithium ions in which the positive electrode and the negative electrode are nonpolarizable electrodes. As a positive electrode material of a lithium ion secondary battery, transition metal complex oxides such as lithium cobaltate and lithium iron phosphate are preferably used. As the negative electrode material, carbonaceous materials such as graphite and non-graphitizable carbon, metal oxides such as lithium titanate, and metal alloys such as silicon and tin are preferably used.

According to the storage device of the present invention, the cell capacity a (mAh) is a capacity when discharging from the fully charged state of the storage device to a voltage half the full charge over 0.75 hours to 1.25 hours, The capacity of the fully charged negative electrode of the electricity storage device was discharged to a negative electrode potential of 1.5 V (Li / Li ⁺ ), and the capacity was taken as a complete negative electrode capacity b (mAh). When the capacity when performing constant current-constant voltage charging (CCCV charging) is defined as a total negative electrode charging capacity c (mAh), 0.35 ≦ a / b ≦ 0.95, 0.55 ≦ b / c ≦ 1. It met 00,0.35 ≦ a / c ≦ 0.55, wherein the electrode density of the positive electrode active material layer is ^{0.54g / cm 3 ~0.7g / cm 3} , and the positive active electrode mass per unit area of the material layer having a characteristic that but a ^70g / ^{m 2 ~110g} / m 2 .

In the present invention, the fully charged state of the power storage device means a charged state which is arbitrarily set within the range of the maximum voltage which can be used over a long period without problems such as gas generation and rise in resistance. The fully charged voltage of the storage device depends on the type of storage device, the material configuration of the positive and negative electrodes, and the electrolyte composition. In the lithium ion capacitor, the full charge voltage is about 3.6 V to 4.0 V, and in the lithium ion secondary battery, the full charge voltage is about 4.1 V to 4.5 V. In the lithium ion capacitor and lithium ion secondary battery, the potential of the negative electrode is preferably 0.2 V (Li / Li ⁺ ) or less at full charge, and is 0.1 V (Li / Li ⁺ ) or less. Is more preferred. Application of a voltage higher than the voltage for full charge is not preferable because it causes deterioration of the storage device.

  The cell capacity a changes depending on the cell size, but when using a positive electrode active material and a negative electrode active material of a predetermined capacity, it can be controlled by adjusting the mass of the positive electrode active material with respect to the mass of the negative electrode active material. Specifically, for example, when the basis weight of the negative electrode active material layer constituting the negative electrode is constant, the cell capacity a can be increased as the basis weight of the positive electrode active material layer is increased.

[Method of measuring cell capacity a]
The cell capacity a is referred to as a current value (hereinafter referred to as “current value α”) in which the discharge time when discharging from the fully charged state to a half voltage of the fully charged voltage is 0.75 to 1.25 hours. It is measured by discharging with. Specifically, first, the storage device is charged with a constant current of current value α until the cell voltage reaches a set voltage related to full charge, and then a constant current-constant voltage charge is applied to apply a fixed voltage of the set voltage Perform (CCCV charge) for 30 minutes to fully charge the battery. Then, from this state, discharge is performed at a constant current of the current value α until the voltage reaches half of the set voltage. By repeating this charge and discharge five times, the storage device is brought into a steady state, and the capacity measured when the battery is discharged for the fifth time is taken as the cell capacity a.

For example, in the case of an electricity storage device having a cell capacity of about 200 mAh, after charging until the cell voltage reaches 3.8 V with a constant current of 200 mA (current value α), the constant voltage of 3.8 V Apply a constant current-constant voltage charge (CCCV charge) for 30 minutes to fully charge the battery, and then discharge from this state until the cell voltage reaches 1.9 V at a constant current of 200 mA (current value α). By doing this, the cell capacity a can be measured. The time required for the discharge at this time is about one hour. If it is discharged at a constant current of 2000 mA, the discharge time will be 6 minutes or less and it will be far below 0.75 hours, though it depends on the internal resistance of the cell, so the exact cell capacity a possessed by the storage device is It can not be measured.
It should be noted that the 0.75 to 1.25 hours specified in the present invention do not mean that any value can be taken, and a current value capable of discharging to a half voltage in about one hour is derived to discharge It specifies the standard time to do. Specifically, it is preferable to set a current value that can discharge in the range of 0.9 hours to 1.1 hours.

  The complete negative electrode capacity b can be controlled by adjusting the amount of lithium ions to be doped into the negative electrode active material constituting the negative electrode during full charge. Specifically, for example, as the thickness of the lithium electrode is increased, the complete negative electrode capacity b can be increased. In addition, when the capacity of the positive electrode is increased, the complete negative electrode capacity b can be increased.

[Method of measuring the complete negative electrode capacity b]
The complete negative electrode capacity b of the storage device is the sum of the negative electrode capacities obtained by the following measurement of each negative electrode in the fully charged storage device.
The complete negative electrode capacity b first charges the storage device with a constant current of current value α until the cell voltage reaches the set voltage, then applies a constant voltage of the set voltage constant current-constant voltage charge (CCCV charge) For 30 minutes to fully charge the battery. Next, this fully charged storage device is decomposed, for example, so that the positive electrode and the negative electrode do not short circuit in the argon box, the negative electrode is taken out, this negative electrode is used as a working electrode, and a lithium metal plate is used as a counter electrode and a reference electrode. A 3-pole cell for measuring the negative electrode capacity is assembled using each of the electrode plates, and this is discharged until the negative electrode potential reaches 1.5 V with a constant current of current value β, and the negative electrode capacity is measured. The total negative electrode capacity b is obtained by multiplying the measured negative electrode capacity by the total number of negative electrodes.
Here, the current value β is the same value as the current value α when there is only one negative electrode constituting the electricity storage device, a plurality of anodes constituting the electricity storage device are plural, and each negative electrode has the same configuration. When it has, it becomes the value which divided electric current value alpha by the number of negative electrodes.
When three or more negative electrodes are contained in the electricity storage device, the negative electrode other than the negative electrode positioned at the outermost position may be selected and taken out as a negative electrode for producing a three-electrode cell for measuring negative electrode capacity. Needed.

For example, in the case of a storage device having a cell capacity of 200 mAh and having 11 negative electrodes of the same configuration, the cell voltage becomes 3.8 V at a constant current of 200 mA (current value α). After charging, constant current-constant voltage charging (CCCV charging) for applying a constant voltage of 3.8 V is performed for 30 minutes to achieve a fully charged state. Next, the fully charged storage device is disassembled so that the positive electrode and the negative electrode do not short circuit in the argon box, and the negative electrode positioned inside is taken out, and this negative electrode is used as a working electrode. 3) and a reference electrode using an electrode plate made of a lithium metal plate to assemble a 3-pole cell for negative electrode capacitance measurement, which is used as a negative electrode at a constant current of 18.2 mA (current value β: 200 mA × 11 pieces) A complete negative electrode capacity b can be obtained by discharging until the potential reaches 1.5 V, measuring the negative electrode capacity, and multiplying this value by 11 times.
The ratio (a / b) of the cell capacity a to the complete negative electrode capacity b in the present invention is 0.35 ≦ a / b ≦ 0.95. When a / b is less than 0.35, the energy density decreases. On the other hand, when a / b is larger than 0.95, lithium deposition easily occurs during the cycle test, the durability is deteriorated, and the capacity reduction due to lithium consumption is accelerated, and the characteristics are deteriorated. a / b is preferably 0.36 ≦ a / b ≦ 0.93, and particularly preferably 0.45 ≦ a / b ≦ 0.7.

In addition, the negative electrode in the electricity storage device of the present invention has a total negative electrode charge capacity c (mAh) when the negative electrode is charged at constant current-constant voltage (CCCV) for 12 hours at 0 V, 0.55 ≦ b It is necessary to satisfy /c≦1.00 and 0.35 ≦ a / c ≦ 0.55.
When the ratio b / c of the complete negative electrode capacity b to the total negative electrode charge capacity c is in the above range, a high capacity retention rate can be obtained in the power storage device, and high durability can be obtained. On the other hand, when b / c is less than 0.55, lithium runs short and cycle durability deteriorates. In addition, when it exceeds 1.00, lithium easily precipitates and the cycle characteristics deteriorate. It is preferable that 0.55 ≦ b / c ≦ 1.00, and particularly preferably 0.70 ≦ b / c ≦ 0.90.

  In addition, when the ratio a / c of the cell capacity a to the total negative electrode charge capacity c is less than 0.35, the energy density decreases. On the other hand, when a / c is larger than 0.55, the capacity reduction at the time of a cycle test becomes large, and durability becomes worse. 0.36 ≦ a / c ≦ 0.54 is preferable, and in particular, 0.4 ≦ a / c ≦ 0.5 is preferably satisfied.

  The total negative electrode charge capacity c can be controlled by adjusting the type and mass of the negative electrode active material contained in the negative electrode. Specifically, for example, as the mass ratio of the negative electrode active material in the negative electrode active material layer is increased, the total negative electrode charge capacity c can be increased. For example, when graphite, the graphite-based composite particles, and the polyacene-based organic semiconductor (PAS) are compared at the same weight as the negative electrode active material, the total negative electrode charge capacity c is larger when PAS is used.

[Method of measuring total negative charge capacity c]
The total negative electrode charge capacity c of the storage device is the sum of the respective negative electrode capacities obtained by the following measurement related to each negative electrode constituting the storage device.
Specifically, first, the total negative electrode charge capacity c charges a 3-pole cell for measuring negative electrode capacity for measuring the complete negative electrode capacity b until the negative electrode potential becomes 0 V with a constant current of current value β The total negative electrode charge capacity c is obtained by performing constant current-constant voltage charge (CCCV charge) applying a constant voltage of 0 V for 12 hours and measuring the negative electrode capacity at this time.
When a plurality of negative electrodes are contained in the storage device, and each negative electrode has the same configuration, the total negative electrode charge capacity c is equal to the negative electrode capacity measured in the 3-electrode cell for measuring the negative electrode capacity. It is obtained by multiplying the number of negative electrodes contained in.

Next, each component which comprises the electrical storage device of this invention is demonstrated.
[Current collector]
The positive electrode and the negative electrode are respectively provided with a positive electrode current collector and a negative electrode current collector for receiving and distributing electricity. As such a positive electrode current collector and a negative electrode current collector, it is preferable to use a current collector having through holes. The form, number, etc. of through holes in the positive electrode current collector and the negative electrode current collector are not particularly limited, and lithium ions and electrolysis are supplied electrochemically from the lithium electrode disposed opposite to at least one of the positive electrode and the negative electrode. It can be set so that lithium ions in the liquid can move between the front and back of the electrode without being blocked by each electrode current collector.

[Positive current collector]
As the positive electrode current collector, a porous current collector having through holes can be used.
The positive electrode current collector having the through holes may be formed, for example, by an expanded metal or punching metal in which a through hole is formed by mechanical implantation to form a through hole penetrating the back surface, or by laser processing using a CO ₂ laser, YAG laser, UV laser or the like. It is possible to use a current collector having a through hole penetrating the surface and a current collector having a through hole formed on the front and back surfaces by etching or electrolytic etching.

  As a material of the positive electrode current collector, aluminum, stainless steel or the like can be used, and aluminum is particularly preferable. Further, the thickness of the positive electrode current collector is not particularly limited, but generally, it may be 1 μm to 50 μm, preferably 5 μm to 40 μm, and particularly preferably 10 μm to 40 μm.

20%-50% are preferable, and, as for the porosity (%) of the through-hole of a positive electrode collector, 20%-40% are more preferable. Here, the porosity (%) of the positive electrode current collector can be determined by the following formula (1).
Porosity (%) = [1- (mass of positive electrode current collector / true specific gravity of positive electrode current collector) / (apparent volume of positive electrode current collector)] × 100 (1)

[Positive electrode active material]
As the positive electrode active material, a material capable of reversibly doping and dedoping at least one anion such as lithium ion and tetrafluoroborate is used, and examples thereof include activated carbon powder. The specific surface area of the activated carbon is preferably 1900m ² / g~3000m ² / g, further preferably a 1950m ² / g~2800m ² / g. The 50% volume cumulative diameter (D50) of the activated carbon is preferably 2 μm to 8 μm, particularly preferably 2 μm to 5 μm, from the viewpoint of the packing density of the activated carbon. When the specific surface area and 50% volume cumulative diameter (D50) of the activated carbon are in the above ranges, the energy density of the storage device can be further improved. Here, the value of the 50% volume cumulative diameter (D50) is determined, for example, by the microtrack method.

[Positive electrode active material layer]
The positive electrode active material layer is formed by applying, printing, injecting, spraying, vapor deposition, pressure bonding or the like the positive electrode active material to the positive electrode current collector. The thickness of the positive electrode active material layer is preferably 55 μm to 95 μm, more preferably 60 μm to 90 μm, and particularly preferably 65 to 80 μm. By setting the layer thickness of the positive electrode active material layer in the above range, the diffusion resistance of ions moving in the positive electrode active material layer can be reduced, whereby the internal resistance can be reduced. And since the positive electrode capacity can be increased, the cell capacity can be increased, and as a result, the capacity of the power storage device can be increased.

[Positive Electrode Active Material Layer: Electrode Density]
Electrode density of the positive electrode active material layer ^{is 0.54g / cm 3 ~0.7g / cm 3} . When the electrode density of the positive electrode active material layer is less than 0.54 g / cm ³ , the energy density is lowered. On the other hand, when the electrode density of the positive electrode active material layer is larger than 0.7 g / cm ³ , the pre-doping property is deteriorated and the cycle characteristics are deteriorated. Electrode density of the positive electrode active material layer ^is preferably from ^{0.54g / cm 3 ~0.68g / cm 3} , and even more preferably ^{0.6g / cm 3 ~0.68g / cm 3} .
The electrode density of the positive electrode active material layer is usually as follows: after the positive electrode obtained by disassembling the storage device is washed with diethyl carbonate and vacuum dried at 100 ° C., the mass of the positive electrode active material layer and the outer shape of the positive electrode active material It is determined by measuring the volume (apparent volume) and dividing the mass of the positive electrode active material layer by the external volume of the positive electrode active material layer. Here, “the external volume of the positive electrode active material layer” is a volume calculated based on the measurement values of the vertical dimension, the horizontal dimension, and the thickness dimension of the positive electrode active material layer.
In addition, as a method of setting an electrode density to the said range, the method of forming by roll press etc. is mentioned.

[Positive electrode active material layer: Weight per unit area]
Electrode area density of the positive-electrode active material layer ^is a ^{70g / m 2 ~110g / m 2} .
When the weight per unit area of the positive electrode active material layer is less than 70 g / cm ² , the energy density of the positive electrode active material layer decreases. On the other hand, when the electrode basis weight of the positive electrode active material layer is larger than 110 g / cm ² , the resistance increases and the cycle characteristics deteriorate. Electrode area density of the positive-electrode active material layer ^is preferably a ^{75g / m 2 ~110g / m 2} .
The basis weight of the positive electrode active material layer is obtained by washing the positive electrode obtained by disassembling the storage device with diethyl carbonate and drying it at 100 ° C., then punching out the active material layer portion to a predetermined area and measuring the mass, The active material layer is peeled off, the mass of the current collector is measured, and the mass of the active material layer is divided by the area.

[Anode current collector]
As the negative electrode current collector, stainless steel, copper, nickel or the like can be used.
The thickness of the negative electrode current collector is not particularly limited, but is usually 1 μm to 50 μm, preferably 5 μm to 40 μm, and particularly preferably 10 μm to 30 μm.

The negative electrode current collector preferably has holes penetrating through the front and back surfaces, and the hole diameter of the through holes is, for example, 0.5 μm to 400 μm, preferably 0.5 μm to 350 μm, and 1 μm. It is particularly preferred that it is ̃330 μm.
Moreover, 20%-70% are preferable, and, as for the porosity (%) of the through-hole of a negative electrode collector, 20%-60% are more preferable. Here, the porosity (%) of the negative electrode current collector can be determined by the following formula (2).
Porosity (%) = [1- (mass of negative electrode current collector / true specific gravity of negative electrode current collector) / (apparent volume of negative electrode current collector)] × 100 (2)
The negative electrode current collector having the through holes is formed, for example, by laser processing using expanded metal or punching metal in which through holes are formed through the back surface by mechanical driving, CO ₂ laser, YAG laser, UV laser or the like. It is possible to use a current collector having a through hole penetrating the back surface, or a current collector having a through hole formed on the front and back by etching.

[Anode active material]
Among the substances capable of reversibly doping and dedoping lithium ions, it is preferable to use graphite-based particles as the negative electrode active material. Specifically, graphite-based composite particles in which the surface of core particles consisting of graphite, non-graphitizable carbon, and natural graphite is coated with a graphitizable substance derived from tar or pitch, and heat-treated aromatic condensation polymers At least one selected from the group consisting of polyacene-based organic semiconductors (PAS) having a polyacene-based framework structure having a hydrogen atom to carbon atom atomic ratio (hydrogen atom / carbon atom) of 0.50 to 0.05 It is preferable to use In the case of PAS, if the atomic ratio of hydrogen atoms to carbon atoms exceeds 0.50, the electron conductivity will be low, and the internal resistance of the cell may be low. On the other hand, when the atomic ratio is less than 0.05, the capacity per unit weight is reduced, and the energy density of the cell may be reduced.
The aromatic condensation polymer refers to a condensation product of an aromatic hydrocarbon compound and an aldehyde. Examples of the aromatic hydrocarbon compound include phenol, cresol, xylenol and the like, and examples of the aldehyde include formaldehyde, acetaldehyde, furfural and the like.

The particle size of the negative electrode active material is preferably graphitic particles having a 50% volume cumulative diameter (D50) in the range of 1.0 μm to 10 μm from the viewpoint of output improvement, and graphite particles in the range of 2 μm to 5 μm More preferable. Graphite-based particles having a 50% volume cumulative diameter (D50) of less than 1.0 μm are difficult to produce, and there is a possibility that the durability may be reduced due to the generation of a gas at the time of charge, for example. On the other hand, with graphite-based particles having a 50% volume cumulative diameter (D50) exceeding 10 μm, it becomes difficult to obtain an electricity storage device with sufficiently low internal resistance.
Moreover, the negative electrode active material preferably has a specific surface area of 0.1m ² / g~200m ² / g, more preferably 0.5m ² / g~50m ² / g. When the specific surface area of the negative electrode active material is less than 0.1 m ² / g, the resistance of the obtained electricity storage device is high, while when the specific surface area of the negative electrode active material exceeds 200 m ² / g, the resistance is obtained. The irreversible capacity at the time of charging of the storage device becomes high, and there is a possibility that the durability may be reduced due to the generation of gas at the time of charging, or the like.
The 50% volume cumulative diameter (D50) of the graphite-based particles is, for example, a value obtained by the microtrack method.

[Anode active material layer]
The negative electrode active material layer is formed by applying, printing, injection, spraying, vapor deposition, pressure bonding, or the like the negative electrode active material to the negative electrode current collector. The preferred range of the thickness of the negative electrode active material layer varies depending on the balance with the mass of the positive electrode active material layer, but the thickness on one side may be 10 μm to 80 μm, preferably 10 μm to 65 μm, and more preferably 10 μm to 50 μm. By setting the layer thickness of the negative electrode active material layer in the above range, the required negative electrode capacity can be secured, and the diffusion resistance of ions moving in the negative electrode active material layer can be reduced. Internal resistance can be reduced.

[Binder]
The preparation of the positive electrode having the positive electrode active material layer as described above and the negative electrode having the negative electrode active material layer can be carried out by a commonly used known method.
For example, each electrode (positive electrode or negative electrode) includes each active material powder (positive electrode active material or negative electrode active material), a binder, and, as necessary, a conductive material, a thickener such as carboxymethyl cellulose (CMC), It can be produced by a method of adding to water or an organic solvent and mixing, applying the obtained slurry to a current collector, or forming the slurry into a sheet and attaching it to a current collector.

In the preparation of each of the above-mentioned electrodes, as the binder, for example, a rubber-based binder such as SBR, a fluorine-containing resin obtained by seed polymerization of polytetrafluoroethylene, polyvinylidene fluoride or the like with an acrylic resin, or an acrylic resin Can be used.
Further, as the conductive material, for example, acetylene black, ketjen black, graphite, metal powder and the like can be mentioned.
Although the addition amount of each of the binder and the conductive material varies depending on the electrical conductivity of the active material to be used, the shape of the electrode to be produced, etc., usually, 2% by mass to 20% by mass with respect to the active material is preferable. In particular, 2% by mass to 10% by mass is more preferable.

[Separator]
As the separator in the electricity storage device of the present invention, a material having an air permeability measured by a method in accordance with JIS P 8117 in the range of 1 sec to 200 sec can be used. Specifically, for example, polyethylene, polypropylene, polyester, cellulose, polyolefin, cellulose / rayon, etc. can be appropriately selected from non-woven fabrics, microporous films, etc. It is preferable to use a rayon non-woven fabric.
The thickness of the separator is, for example, 5 μm to 20 μm, and preferably 5 μm to 15 μm. If the thickness of the separator is less than 5 μm, a short circuit is likely to occur. On the other hand, when it is larger than 20 μm, the resistance becomes high.

[Electrolyte solution]
In the electricity storage device of the present invention, an aprotic organic solvent electrolyte solution of lithium salt is used as the electrolytic solution.

[Aprotic Organic Solvent of Electrolyte]
Examples of the aprotic organic solvent constituting the electrolytic solution include ethylene carbonate (hereinafter also referred to as "EC"), propylene carbonate (hereinafter also referred to as "PC"), cyclic carbonates such as butylene carbonate, and dimethyl carbonate. (Hereinafter, it is also called "DMC".), Ethyl methyl carbonate (hereinafter, also called "EMC"), diethyl carbonate (hereinafter, also called "DEC"), linear carbonates such as methyl propyl carbonate and the like. You may use the mixed solvent which mixed 2 or more types in these.
In the present invention, the aprotic organic solvent constituting the electrolytic solution is an organic solvent other than cyclic carbonate and chain carbonate, for example, cyclic ester such as γ-butyrolactone, cyclic sulfone such as sulfolane, cyclic ether such as dioxolane, propionic acid It may contain a chain carboxylic acid ester such as ethyl, a chain ether such as dimethoxyethane, and the like.

〔Electrolytes〕
Examples of lithium salts of the electrolyte in the electrolytic solution include LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiPF ₆ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) _{2 and the} like, and in particular, LiPF ₆ is preferably used because of high ion conductivity and low resistance. The concentration of the lithium salt in the electrolytic solution is preferably 0.1 mol / L or more, and more preferably 0.5 to 1.5 mol / L, since a low internal resistance can be obtained.

The power storage device of the present invention has a capacity retention rate of 95% or more after performing 10,000 cycles of constant current charge / discharge at a time rate of 10 C in a voltage range of 3.8 V to 2.2 V. Furthermore, the storage device of the present invention has an internal resistance increase rate of 3% or less after performing 10000 cycles of constant current charge / discharge at a time rate of 10 C in a voltage range of 3.8 V to 2.2 V. This is because the storage device of the present invention satisfies 0.35 ≦ a / b ≦ 0.95, 0.55 ≦ b / c ≦ 1.00, 0.35 ≦ a / c ≦ 0.55, and the positive electrode in the electrode density of the active material layer is ^{0.54g / cm 3 ~0.7g / cm 3} , and the electrode weight per unit area of the positive active material layer by filling ^{70g / m 2 ~110g / m 2} , higher capacity This indicates that the maintenance rate can be maintained and the increase in internal resistance can be suppressed. With the configuration of the storage device of the present invention, it is possible to maintain a good balance between the tradeoff between high output and high energy density.

[Structure of electricity storage device]
As the structure of the electricity storage device of the present invention, in particular, three or more layers of wound-type, plate-like or sheet-like positive and negative electrodes are wound via a separator to form a strip-like positive electrode and negative electrode. The laminated type, and the laminated type in which the unit of the structure laminated in this way is enclosed in an exterior film or a square-shaped exterior can etc. are mentioned.
The structures of these power storage devices are known, for example, from Japanese Patent Application Laid-Open No. 2004-266091 and the like, and can have the same configuration as those power storage devices.

As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to said example, A various change can be added.
For example, the electricity storage device of the present invention is not limited to a wound or stacked lithium ion capacitor, and can be suitably applied to lithium ion secondary batteries and other electricity storage devices.

  EXAMPLES Hereinafter, specific examples of the present invention will be described, but the present invention is not construed as being limited to these examples.

Example 1 (S1) Production Example 1 of Cell
(1) Production of Positive Electrode A conductive paint (Bunny Height T-602DEFK made by Nippon Graphite Co., Ltd.) is applied to both sides of a current collector material made of aluminum electrolytic etching foil having a pore diameter of 1 μm and a thickness of 30 μm. The coating width was set to 100 mm, and the coating thickness on both sides was set to 125 μm using a machine, and then the both sides were coated, and then dried under reduced pressure to form conductive layers on the front and back surfaces of the positive electrode current collector.
Next, activated carbon particles having a 50% volume cumulative diameter (D50) value of 3 μm and a specific surface area of 2000 m ² / g on the conductive layers formed on the front and back surfaces of the positive electrode current collector (Catalar: -CEP21K) 43% by weight (positive electrode active material), 1.5% by weight of binder (manufactured by JSR: TRD 201B), 2% by weight of carboxyl methylcellulose sodium salt (manufactured by Daicel, 1120), acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd .: A slurry containing 2.5 wt% of HS100) and 51 wt% of water is coated on both sides using a vertical die type double-sided coater, and then dried under reduced pressure and roll pressed to form an electrode on the conductive layer. The positive electrode active material layer which is a layer was formed.
In this way, the layer (hereinafter also referred to as “coated part” for the positive electrode) of the positive electrode current collector on which the conductive layer and the electrode layer are stacked is 60 mm × 80 mm, and no layer is formed. The electrode layer is formed on both sides of the positive electrode current collector by cutting it to a size of 60 mm × 95 mm so that a portion (hereinafter, also referred to as “uncoated portion” for the positive electrode) is 60 mm × 15 mm. A positive electrode was produced.

(2) Preparation of Negative Electrode Graphite particles having a 50% volume cumulative diameter (D50) of 6 μm on both sides of a negative electrode current collector made of copper chemical etching foil having a through hole diameter of 300 μm, a porosity of 55% and a thickness of 25 μm. Graphite-based composite particles (1) (Nippon Carbon Co., Ltd .: AGP30) (negative electrode active material) with a pitch coated on the surface, 40 wt% SBR binder (JSR Co .: TRD 2001), and 1 wt% of carboxymethylcellulose sodium salt (Daicel Corporation: 1120) A slurry containing 1.5 wt%, 2 wt% of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd .: HS 100), and 55.5 wt% of water was coated on both sides using a vertical die type double-sided coater. Thereafter, the resultant was dried and roll pressed to form a negative electrode active material layer as an electrode layer on the front and back surfaces of the negative electrode current collector.
A portion (hereinafter, also referred to as a "coated portion" for the negative electrode) on which the electrode layer of the negative electrode current collector obtained in this manner is 65 mm x 85 mm, and a portion where the electrode layer is not formed (hereinafter, The negative electrode was formed on both sides of the negative electrode current collector by cutting the negative electrode into a size of 65 mm × 100 mm so that “uncoated portion” is 65 mm × 15 mm. .

(3) Preparation of Separator A film made of a cellulose / rayon composite material with a thickness of 15 μm and an air permeability of 100 sec was cut into 70 mm × 91 mm to prepare a separator.

(4) Preparation of lithium ion capacitor element First, 10 positive electrodes, 11 negative electrodes and 22 separators are prepared, and the coated portions of the positive electrode and the negative electrode overlap, but the uncoated portions thereof are on the opposite side The electrode laminate unit was manufactured by stacking the separator, the negative electrode, the separator, and the positive electrode in this order and fixing the four sides of the laminate with a tape so as not to overlap.
Next, a lithium ion supply member is manufactured by cutting a foil-like lithium metal having a thickness of 46 μm so that the size is 65 mm × 85 mm, and pressing it on a 25 μm thick copper foil (made by Japan Foil Co., Ltd.) The lithium ion supply member is disposed to face the negative electrode through the separator of the electrode stack unit.
Then, for the positive electrode made of aluminum having a width of 50 mm, a length of 50 mm, and a thickness of 0.15 mm, the sealant film was heat-sealed in advance to the seal portion in the uncoated portions of each of the 10 positive electrodes of the electrode lamination unit produced. The power tabs were stacked and welded. On the other hand, a sealant film was heat-sealed in advance to the seal portion in each of the uncoated portion of each of the 11 negative electrodes of the electrode lamination unit and the lithium ion supply member 50 mm wide, 50 mm long, 0.2 mm thick Copper negative electrode power tabs were overlapped and welded. Thus, a lithium ion capacitor element was obtained.

(5) Preparation of lithium ion capacitor A polypropylene layer, an aluminum layer and a nylon layer are laminated, and the dimensions are 90 mm (vertical width) x 127 mm (horizontal width) x 0.15 mm (thickness), and 72 mm (vertical width) at the central portion One exterior film subjected to drawing processing of 105 mm (horizontal width) and a polypropylene layer, an aluminum layer and a nylon layer are laminated, and the other is 90 mm (vertical width) × 127 mm (horizontal width) × 0.15 mm (thickness) The exterior film of was produced.

Next, the lithium ion capacitor element described above is projected to a position where it will be the housing portion on the other exterior film, with each of the positive electrode terminal and the negative electrode terminal of the electrode laminate unit projecting outward from the end of the other exterior film I arranged it. One exterior film was laminated on this electrode laminate unit, and three sides (including two sides from which the positive electrode terminal and the negative electrode terminal project) in the outer peripheral edge portion of one exterior film and the other exterior film were heat-sealed.
On the other hand, a mixed solvent of ethylene carbonate, propylene carbonate and diethyl carbonate (3: 1: 4, respectively, in volume ratio) is used as the aprotic organic solvent, and an electrolyte containing 1.2 mol / L of LiPF ₆ is used. Prepared.
Subsequently, after pouring the said electrolyte solution between one exterior film and the other exterior film, the other side in the outer-periphery part of one exterior film and the other exterior film was heat-seal | fused. Then, in this state, lithium ions were doped from the lithium foil (lithium ion supply member) to the negative electrode by standing for 10 days.
As described above, a laminate exterior lithium ion capacitor for test (hereinafter, referred to as cell 1) was produced. In addition, four similar cells 1 were produced in total.
The average cell capacity of the obtained cell 1 was 190 mAh.

[Positive electrode active material layer: Density]
The positive electrode obtained by disassembling one cell 1 is immersed in a container containing diethyl carbonate for 30 minutes, washed, vacuum dried at 100 ° C., and then the active material layer is present anywhere Two pieces were cut into a size of 2 cm ² , the weight of one cut-out positive electrode was measured by an electronic balance, and the thickness was measured by a micrometer. Subsequently, only the current collector of the uncoated region where the active material layer was not present was cut out to the same size, the weight was measured by an electronic balance, and the thickness was measured by a micrometer. The weight of the positive electrode active material layer was calculated by subtracting the weight of only the obtained current collector from the weight of the positive electrode. Subsequently, the thickness of only the obtained current collector was subtracted from the thickness of the positive electrode, the thickness of the positive electrode active material layer was calculated, and the external volume (apparent volume) of the positive electrode active material was calculated. Then, the mass of the positive electrode active material layer was divided by the external volume of the positive electrode active material layer to determine the density of the positive electrode active material layer.

[Positive electrode active material layer: Weight per unit area]
The weight of the remaining 2 cm × 2 cm positive electrode made when measuring the density of the positive electrode active material layer is measured with an electronic balance, the active material layer is peeled off, and the mass of the current collector is measured. The coating weight of the positive electrode active material layer was calculated by dividing the mass of the above by the area.

[Evaluation of cell performance]
For the remaining three cells 1 obtained, the cell capacity a, the complete negative electrode capacity b, the total negative electrode charge capacity c, the energy density and the DC-IR are measured and the durability test is performed as follows. The evaluation of

(I) Measurement of Cell Capacity a and Calculation of Energy Density For one cell 1, after charging to a cell voltage of 3.8 V with a constant current of 0.19 A (current value α), 3.8 V After performing constant-voltage charging for 30 minutes, the charge and discharge operation of discharging the cell voltage to 1.9 V at a constant current of 0.19 A was repeated five times. The capacity at the time of discharge in the fifth charge and discharge operation was taken as the cell capacity a. The results based on the cell capacity a are shown in Table 1. The time required for the discharge in the fifth charge and discharge operation was 1.04 hours.
The product of the obtained cell capacity a and the average cell voltage divided by the volume of the cell 1 is shown in Table 1 as the energy density (Wh / L).

(Ii) Measurement of Complete Negative Electrode Capacitance b After measuring the cell capacity a, charge the cell 1 with a constant current of 0.19 A until the cell voltage is 3.8 V, and then charge 3.8 V at a constant voltage. It went for 30 minutes and was fully charged. The fully charged cell 1 is disassembled, and the negative electrode is taken out, and a negative electrode capacity measuring cell using a lithium metal plate as a counter electrode is assembled, and the negative electrode potential is 1.5 V (Li / A value obtained by multiplying the negative electrode capacity when discharged to Li ⁺ ) by 11 (the number of negative electrodes) is taken as a complete negative electrode capacity b, and the result based on the complete negative electrode capacity b is shown in Table 1.

(Iii) Measurement of total negative electrode charge capacity c For the negative electrode capacity measurement cell, after measurement of the above-mentioned complete negative electrode capacity b, in the same manner as measurement of the above-mentioned cell capacity a, the voltage of the cell at a constant current of 0.0173A. After charging to 0V, constant voltage charging at 0V was performed for 12 hours. A value obtained by multiplying the negative electrode capacity at this time by 11 (the number of negative electrodes) is taken as a total negative electrode charge capacity c, and the result based on the total negative electrode charge capacity c is shown in Table 1.

(Iv) Measurement of DC-IR With respect to the cell before measurement of capacity retention rate, charge the cell voltage to 3.8 V at a constant current of 1.9 A (time rate 10 C) before starting the cycle test, and then 3. The constant current-constant voltage charge which applies a constant voltage of 8 V was performed for 0.5 hour, and then it was discharged until the cell voltage became 2.2 V at a constant current of 19 A (time rate 100 C). At that time, take an approximate straight line of the voltage after 1 second and 3 seconds, extrapolate to 0 second, and divide the difference (ΔV) between the extrapolated voltage and 3.8 V by the current value 19A to obtain a DC value. Internal resistance (DC-IR).

(V) Cycle characteristics test:
[Capacity maintenance rate]
After charging the above cell 1 to a cell voltage of 3.8 V with a constant current of 1.9 A (time rate 10 C), the cell voltage becomes 2.2 V at a constant current of 1.9 A A cycle test was performed in which the charge and discharge cycle of discharging up to 10,000 times was repeated. The ratio of the capacity at the 10,000th cycle to the capacity at the first cycle in this cycle test is shown in Table 1 as a capacity retention ratio. The case where the capacity retention rate is 95% or more is shown as “○”, the case where it is 90% or more and less than 95% as “Δ”, and the case where it is less than 90% as “x”.
[Rise rate of resistance]
Charge the cell for measuring capacity retention rate until the cell voltage reaches 3.8 V with constant current of 1.9 A (time rate 10 C) before and after the start of cycle test, and then apply constant voltage of 3.8 V The current-constant voltage charging was performed for 0.5 hours, and then the cell voltage was discharged at a constant current of 19 A (time rate 100 C) until the cell voltage became 2.2 V. This 3.8 V-2.2 V cycle was repeated, and the 10th direct current internal resistance was measured. The case where the rate of increase in resistance before and after the cycle test is 3% or less is shown as “○”, the case where it is more than 3% and 5% or less is “Δ”, and the case where it is more than 5% is shown as “x”.

〔Comprehensive judgment〕
It operates without any problems such as short-circuiting of the manufactured cell, and when the initial DC-IR is 10.35 mΩ or less and the energy density is more than 31.5 Wh / L, it is ○. Furthermore, when the capacity retention rate is 95% or more and the resistance increase rate is 3% or less, it is assumed that the value is 〇. If it is out of the above range, it will be x.

[Production Example of Cells of Example 2 (S2) to Example 13 (S13) and Comparative Examples 1 (C1) to 10 (S10)]
In Production Example 1 of the cell of Example 1, the electrode density and basis weight of the positive electrode active material layer, a / b, b / c, and a / c are as shown in Table 1, and the separator thickness is changed according to Table 1 S2 to S13 and C1 to C10 were respectively produced four each in the same manner as described above.
The cell capacity a, the complete negative electrode capacity b, the total negative electrode charge capacity c, the energy density and the DC-IR are measured for these S2 to S13 in the same manner as in Example 1, and the cycle characteristics test is performed to evaluate the characteristics. Did. In the DC-IR measurement and the cycle characteristic test, the current value was changed in accordance with the capacity of each cell so that the time rate matches the case of Example 1.
The results based on these results are shown in Table 1.

As shown in Table 1, 0.35 ≦ a / b ≦ 0.95, 0.55 ≦ b / c ≦ 1.00, 0.35 ≦ a / c ≦ 0.55, and the positive electrode active material in the electrode density of the layer is ^{0.54g / cm 3 ~0.7g / cm 3} , if the and the positive electrode active cell electrodes basis weight of the material layer satisfies the ^{70g / m 2 ~110g / m 2} , DC-IR In other words, it was possible to obtain an electricity storage device having a good balance of performances that can suppress the low power, that is, the output is large, the energy density is high, and the capacity decrease after cycle test and the resistance increase can be suppressed.

Since a / c was larger than 0.54, the cell C1 had a large capacity reduction at the time of the cycle test and the characteristics deteriorated.
The C2 cell has a reduced energy density because a / c is less than 0.35.
Since b / c of the C3 cell exceeded 1.00, the capacity reduction at the time of the cycle test became large and the characteristics of the cell deteriorated.
Since the b / c of the C4 cell was less than 0.55, the capacity decreased and the resistance increased during the cycle test, and the characteristics deteriorated.
Since the cell weight of the positive electrode active material layer of the C5 cell is greater than 110 g / cm ² , the initial DC-IR is high, and resistance increase and capacity decrease occur in the cycle test, resulting in deterioration of the cell characteristics.
The energy density of the C6 cell was reduced because the electrode weight per unit area of the positive electrode active material layer was less than 70 g / cm ² .
Since the cell density of the positive electrode active material layer of the C7 cell is higher than 0.7 g / cm ³ , the initial DC-IR is high, the capacity decreases and the resistance increase occurs in the cycle test, and the cell characteristics deteriorate.
On the other hand, the energy density of the C8 cell was lowered because the electrode density of the positive electrode active material layer was less than 0.54 g / cm ³ .
Since a / b of the C9 cell is greater than 0.95, the capacity decreases and the resistance increases in the cycle test, and the characteristics of the cell deteriorate.
Since a / b of the cell of C10 is less than 0.35, capacity decrease and resistance increase occur in the cycle test, and the characteristics of the cell deteriorate.
From the above results, since each of Comparative Examples C1 to C10 is a storage device that does not satisfy any of the configurations of the present invention, the target output of the present application is large, the energy density is high, and the capacity decreases after the cycle test. It was not possible to obtain a power storage device with a good balance of performance that can suppress an increase in resistance.

The storage device of the present invention can obtain high energy density and high output characteristics without deterioration even if the capacity of the negative electrode is increased, and is widely used as a lithium ion capacitor, lithium ion secondary battery, etc. Ru.
The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2013-146835 filed on July 12, 2013 are incorporated herein by reference and incorporated as disclosure of the specification of the present invention. It is a thing.

Claims (12)

An electrode unit in which a positive electrode having a positive electrode active material layer formed on a positive electrode current collector and a negative electrode having a negative electrode active material layer formed on a negative electrode current collector are alternately stacked via a separator; What is claimed is: 1. An electricity storage device comprising: an electrolyte comprising an aprotic organic solvent solution of a salt;
The capacity when discharged from the fully charged state of the storage device to a half voltage of the fully charged voltage over 0.75 to 1.25 hours is defined as a cell capacity a (mAh), and the fully charged state of the storage device The capacity when the negative electrode is discharged to a negative electrode potential of 1.5 V (Li / Li ⁺ ) is a complete negative electrode capacity b (mAh), and the negative electrode is charged at constant current-constant voltage for 12 hours at 0 V Assuming that the capacity when CCCV charging is performed is the total negative electrode charging capacity c (mAh), 0.35 ≦ a / b ≦ 0.95, 0.55 ≦ b / c ≦ 1.00, 0.35 ≦ a / met c ≦ 0.55, the positive electrode active at the electrode density of the material layer is ^{0.54g / cm 3 ~0.7g / cm 3} , and the positive electrode active material layer electrode weight per unit area 70g / m ² ~110g / An electric storage device characterized by having m ² . Storage device according to claim 1 electrode unit weight of the positive active material layer is ^{75g / m 2 ~110g / m 2} . The power storage device according to claim 1, wherein the negative electrode active material layer contains graphite-based particles . The power storage device according to any one of claims 1 to 3, wherein the positive electrode active material layer contains activated carbon . The thickness of the said separator is 5 micrometers-20 micrometers, The electrical storage device of any one of Claims 1-4. The electricity storage device according to any one of claims 1 to 5, wherein the positive electrode current collector and / or the negative electrode current collector has a through hole . The power storage device according to any one of claims 1 to 6, wherein the electrode unit is a stacked type or a wound type . The electricity storage device according to any one of claims 1 to 7, wherein the negative electrode is a negative electrode in which lithium ions are doped in advance . The electricity storage device according to any one of claims 1 to 8, which is a lithium ion capacitor . The energy storage device according to claim 9 , having an energy density of 31.5 Wh / L or more . The capacity retention ratio after performing 10000 cycles of constant current charge / discharge with a time rate of 10 C in a voltage range of 3.8 V to 2.2 V is 95% or more, any one of claims 1 to 10 Storage device of description. 12. The internal resistance increase rate after performing 10000 cycles of constant current charge / discharge at a time rate of 10 C in a voltage range of 3.8 V to 2.2 V is 3% or less. Power storage device according to.