JP2001196273A - Electric double layer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric double layer capacitor having a low-cost constitution with an optimum quantity of impregnated electrolyte which minimizes the internal resistance and requires least electrolyte. SOLUTION: An appropriate quantity of electrolyte to the total pore volume, i.e., the sum of the pore volumes of carbon electrodes 2 and a separator 3 is impregnated to minimize the internal resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the storage of electric energy, and more particularly to an electric double layer capacitor used as an auxiliary power source for an electric vehicle, an electric double layer capacitor used to store surplus power at night, a fuel cell and a solar cell. The present invention relates to an electric double layer capacitor used for accumulating generated electric energy, and an electric double layer capacitor used for an emergency power supply or a backup power supply.

[0002]

2. Description of the Related Art In recent years, environmental destruction has been called a global scale for a long time, and the importance of countermeasures has been increasing day by day. For this reason, effective utilization of energy and review of energy saving technologies and development of new technologies are being promoted both in Japan and overseas and in the public and private sectors.

[0003] These are, for example, development of a hybrid electric vehicle or an electric vehicle itself combining a gasoline engine and an electric motor, development of an ice heat storage technology aiming at effective utilization of nighttime electric power in an urban area, or excellent environmental performance. The development of a fuel cell with high power generation efficiency, and the development of a solar cell using solar energy, and the like are also included.

A power storage element for a hybrid electric vehicle, an electric vehicle, or an electric business, an electric energy storage element used in combination with a fuel cell or a solar cell, and an electric energy used for an emergency power supply or a backup power supply As the storage element, a secondary battery (usually called a battery) has been used alone,
Recently, in combination with a secondary battery or alone,
A large-capacity electric double layer capacitor has been used.

[0005] It is clear that the electric double layer capacitor has a higher output density and a superior charge / discharge cycle than the secondary battery, while the secondary battery has a superior energy density as compared with the electric double layer capacitor. Has become.

Therefore, the electric double layer capacitor has an issue of increasing the energy density, and the secondary battery has an issue of improving the power density and the charge / discharge cycle. On the other hand, the secondary battery and the electric double layer capacitor are complementary. Uses in combination with capacitors are increasing in various fields.

[0007]

Conventionally, an electric double layer capacitor is a carbon electrode made of activated carbon having a large specific surface area, supporting a porous and electrically insulating separator, and applying an electrolytic solution to the electrode and the separator. The electric double layer capacitor is formed by impregnation.

At this time, since the amount of the electrolyte impregnated and the concentration of the electrolyte are closely related to the internal resistance of the electric double layer capacitor, it forms one of the fundamentals of the electric double layer capacitor technology. The relationship between the amount of electrolyte impregnation and electrolyte concentration and the internal resistance of an electric double layer capacitor is not disclosed as one of the most important know-hows of Japanese manufacturers, and its quantitative discussion is not public. is the current situation.

This is because the reduction of the internal resistance directly affects the output density and the energy density of the electric double layer capacitor.

On the other hand, two types of electric double layer capacitors have been developed so far. One of them is an aqueous electrolytic solution electric double layer capacitor using sulfuric acid as an electrolyte and water as a solvent. The other is a non-aqueous solvent-based organic electrolytic solution electric double layer capacitor using tetraethylammonium boron tetrafluoride as an electrolyte and propylene carbonate as a solvent.

Among these, the latter non-aqueous solvent-based organic electrolyte capacitor is relatively expensive in terms of the electrolyte and the solvent as compared with the aqueous electrolyte solution. From the viewpoint of, it is important to optimize the amount of electrolyte impregnation and the concentration of the electrolyte.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive electric double layer capacitor with an optimum electrolyte impregnation amount which minimizes internal resistance and does not require an excessive amount of electrolyte solution.

It is another object of the present invention to provide an inexpensive electric double layer capacitor having an optimum electrolyte concentration which minimizes internal resistance and does not unnecessarily increase the electrolyte concentration.

[0014]

The present invention relates to an electric double layer capacitor constituted by impregnating a carbon electrode and a separator sandwiched between the carbon electrodes with an electrolyte, wherein the energy involved in the charging and discharging is provided. The electric double layer capacitor is configured by setting the internal resistance relating to the charge / discharge to a predetermined value so that the density or the output density maintains a constant value.

Here, the predetermined value of the internal resistance relating to the charging and discharging may be set to a minimum value.

[0016] The amount of the electrolytic solution impregnated into the carbon electrode and the separator may be quantitatively changed so that the internal resistance relating to the charge and discharge becomes a predetermined value.

A sulfuric acid electrolytic solution is used as the electrolytic solution impregnated in the carbon electrode and the separator, and the amount of impregnation of the electrolytic solution with respect to the total pore volume obtained by adding the pore volumes of the carbon electrode and the separator to each other Is the total pore volume ratio, the total pore volume ratio may be 0.7 or more.

As a non-aqueous solvent organic electrolyte obtained by dissolving a tetraethylammonium boron tetrafluoride electrolyte in a propylene carbonate solvent as an electrolytic solution impregnated in the carbon electrode and the separator, each of the carbon electrode and the separator is used. When the impregnation amount of the electrolytic solution is defined as the total pore volume ratio, based on the total pore volume obtained by summing the pore volumes,
The total pore volume ratio may be 0.8 or more.

The total pore volume ratio may be 0.8 or more and 1.0 or less.

[0020] The electrolyte concentration of the electrolytic solution impregnated in the carbon electrode and the separator may be quantitatively changed so that the internal resistance relating to the charge and discharge becomes a predetermined value.

A sulfuric acid electrolyte is used as the electrolyte impregnated in the carbon electrode and the separator, and the electrolyte concentration of the electrolyte is 20% by weight or more, and
It may be set at 35% by weight or less.

As an electrolyte solution impregnated in the carbon electrode and the separator, a non-aqueous solvent organic electrolyte solution in which a boron tetrafluoride tetraethylammonium electrolyte is dissolved in a propylene carbonate solvent is used.
It may be set to 0.9 mol or more.

The electrolyte concentration of the electrolyte may be set to 0.9 mol or more and 1.0 mol or less.

As a binder for the carbon electrode, polyethylene tetrafluoride may be used. A porous and electronically insulating substance may be used as the separator.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. [First Example] FIGS. 1 to 2 show a first embodiment of the present invention.
It will be described based on.

FIG. 1 shows a sectional shape of the electric double layer capacitor.

The electric double layer capacitor 1 includes a carbon electrode 2, a separator 3 for separating the electrode 2 at a central portion,
It comprises a current collecting plate 4 provided at both ends of the electrode 2, an electrode lead wire 5 connected to the current collecting plate 4, and an insulating cell frame 6.

Here, a specific configuration example of the electric double layer capacitor 1 will be described.

As the carbon material of the carbon electrode 2, for example, Black Pearl 2000 (manufactured by Cabot) is used, and as the binder, for example, polyethylene tetrafluoride is used. Then, a carbon sheet containing a predetermined amount of polytetrafluoroethylene having a thickness of 0.5 mm is prepared by a normal calender roll method.

Next, the carbon sheet was set to an outer diameter of 16 m.
The carbon electrode 2 is manufactured by punching two sheets each having a size of m and an area of 2 cm ² and impregnating each with a predetermined electrolytic solution.

Then, as shown in FIG. 1, the carbon electrode 2 is separated at the center using a separator 3 made of an electronically insulating porous pulp paper having a thickness of 0.3 mm and previously punched into an outer diameter of 17 mm. By doing so, the electric double layer capacitor 1 of the sulfuric acid electrolytic solution is formed. (Experimental Example) Next, the relationship between the internal resistance R and the amount of electrolyte impregnation in the electric double layer capacitor 1 is measured.

A 30 wt% sulfuric acid solution is used as an electrolyte for impregnation, and gold is used as a current collector 4.

Then, the internal resistance R is measured by a constant current method at a current density of 50 mA / cm ² at a charging voltage of 1 V. At this time, the constant current charge / discharge was performed up to 10,000 times.

The pore volume is determined by previously measuring the pore volume per unit weight of the carbon sheet and the pulp paper by the Archimedes method, and multiplying them by the weights of the carbon electrode 2 and the separator 3. The total pore volume was determined by calculating and summing the pore volumes. Note that the total pore volume may be measured by a porro shutter.

FIG. 2 shows the relationship between the ratio of the amount of electrolyte impregnation to the total pore volume (hereinafter referred to as the total pore volume ratio) and the internal resistance R.

First, the internal resistance R at the fifth charge / discharge initial stage
Increased gradually when the total pore volume ratio was 0.6 or less, became ² Ωcm ² when the ratio was 0.3, and sharply increased when the ratio was 0.2 or less.

The internal resistance R is such that the total pore volume ratio is equal to 0.
At 7 or more, it converges to 1 Ωcm ² , and even at 1.1 or 1.2 with a total pore volume ratio of 1.0 or more, it does not decrease as in the case of 1.0.

This indicates that the excess electrolyte having a total pore volume ratio of 1.0 or more does not help reduce the internal resistance R at all.

Next, the internal resistance R at the 10,000th constant current charge / discharge is larger than the value at the fifth charge / discharge.

When the total pore volume ratio is 0.3, several hundreds
Charging / discharging became impossible in the first order. The reason for this is that as the amount of the electrolyte decreases, the conduction of the electrolyte between the anode and the cathode decreases, and it is assumed that the electrolyte is cut off at 0.3 or less. In addition, the total pore volume ratio is 0.7
Above, the internal resistance R increases slightly but almost 5
It is not different from the second internal resistance.

Even at 1.1 or 1.2, the same tendency as in the fifth time was obtained.
It does not contribute to the reduction of the internal resistance R.

From the above experimental results, it was found that 30 wt%
It can be seen that in the electric double layer capacitor 1 using sulfuric acid, the impregnation amount of the electrolytic solution is desirably 0.7 or more in total pore volume ratio.

As described above, the electric double layer capacitor 1
In the above, the relationship between the internal resistance R and the electrolyte impregnation amount was carefully and carefully examined, and as a result, the electrolyte impregnation amount was calculated as the total pore volume obtained by summing the respective pore volumes of the carbon electrode 2 and the separator 3. By determining the relationship between the ratio and the internal resistance, it was found that there was a clear correlation.

That is, the carbon electrode 2 and the separator 3
By impregnating an appropriate amount of electrolyte with respect to the total pore volume obtained by summing the respective pore volumes, the internal resistance R can be minimized and the cost can be minimized. [Second Example] Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. The description of the same parts as those in the first example is omitted, and the same reference numerals are given.

This example is a modification of the above-described first example. Then, similarly to FIG. 1 described above, this is an example of the case where the electric resistance R is evaluated by configuring the electric double layer capacitor 1 of the non-aqueous solvent liquid organic electrolyte using the carbon electrode 2 and the separator 3. .

What differs from the first example is the values of the electrolyte and the charging voltage. That is, an organic electrolyte obtained by dissolving 1 mol of boron tetrafluoride tetraethylammonium electrolyte in 1 liter of propylene carbonate solvent is used as the electrolyte. The charging voltage is 3.5V.

FIG. 3 shows the relationship between the ratio of the electrolyte impregnation amount to the total pore volume (hereinafter referred to as the total pore volume ratio) and the internal resistance R.

First, the fifth internal resistance R at the beginning of charging and discharging
When the total pore volume ratio was 0.7 or less, the ratio rapidly increased, and when the ratio was 0.4 or less, charging and discharging became impossible. This reason is presumed to be due to the same factors as in the first example.

The internal resistance R is such that the total pore volume ratio is equal to 0.
At 8 or more, it gradually decreases and is not as convergent as the first example, but converges to 13 to 14 Ωcm ² .

In the case of 1.1 and 1.2 having a total pore volume ratio of 1.0 or more, the internal resistance R is 4.2 compared to 1.0.
It is reduced to 1% and 8.11%.

This indicates that, unlike the first example, the extra electrolyte having a total pore volume ratio of 1.0 or more helps to reduce the internal resistance R.

Now, the total pore volume ratios 1.1 and 1.
The reduction of the internal resistance R in the case of 2 will be further studied.

These internal resistances R are calculated based on the total pore volume ratio of 1.
It is a decrease of 0.9579 and 0.9189 with respect to 0, and it is important how much the decrease has an effect on the increase of “power density” and “energy density”.

Although it is case-by-case related to the parts, weight, and configuration of the electric double layer capacitor 1, it generally falls short of the reciprocals of the internal resistance reduction ratio, 1.044 and 1.088. In particular, it is extremely small with respect to an increase in energy density.

Incidentally, the price of the electric double layer capacitor 1 is defined with respect to the energy density.

As described above, the material cost of the organic electrolyte is relatively high, and is generally considered to be higher than other members constituting the electric double layer capacitor 1.

Accordingly, for a total pore volume ratio of 1.0,
Increases of 0.1 and 0.2 are more expensive in terms of price. Of course, the price for the increase is also reduced by the mass production effect.

However, the very small increase in the energy density does not compensate for the increase in the cost of the extra electrolyte solution, thereby increasing the price defined by the energy density. Thus, when the amount of the electrolyte is discussed from the viewpoint of price, it is understood that the total pore volume ratio is desirably 1.0 or less.

Next, as in the first example, the internal resistance R at the 10,000th constant current charging / discharging is larger than each value at the fifth time. Charging and discharging became impossible.

However, when the total pore volume ratio of the electrolyte impregnation amount is 0.8 or more, the internal resistance R slightly increases,
It is almost the same as the fifth internal resistance R. Further, even when the total pore volume ratio is 1.1 or 1.2, the tendency is not different from the tendency at the fifth time.

From the above results, in the electric double layer capacitor 1 using an organic electrolyte obtained by dissolving 1 mol of boron tetrafluoride tetraethylammonium electrolyte in 1 liter of propylene carbonate solvent, the impregnation amount of the electrolyte is It can be seen that it is desirable that the total pore volume ratio be 0.8 or more and 1.0 or less. Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG.
It will be described based on. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached.

In this example, similarly to FIG. 1 of the first example, an electric double layer capacitor 1 is formed using a carbon electrode 2 and a separator 3, and the internal resistance R is evaluated.

The electrolytic solution is impregnated with a predetermined amount of a sulfuric acid solution having a predetermined weight percent concentration prepared separately.

Here, the latter predetermined amount means the following amount. That is, the above-mentioned total pore volume ratio is 1.0.
Is the amount corresponding to The total pore volume ratio is a ratio of the amount of the electrolyte to the total pore volume obtained by summing the respective pore volumes of the carbon electrode 2 and the separator 3. The total pore volume ratio of 1.0 physically means that the pores of the carbon electrode 2 and the separator 3 are just filled with the electrolyte, and the internal resistance R is minimized.

The internal resistance R is measured by a constant current method with a current density of 50 mA / cm ^{2 at} a charging voltage of 1 V. At this time, the constant current charge / discharge was performed up to 10,000 times.

FIG. 4 shows the weight percent concentration of sulfuric acid (FIG. 4).
In the graph, the relationship between the electrolyte concentration and the internal resistance R is shown. Here, the electrolyte impregnation amount is 1.0 as the total pore volume ratio as described above. First, the internal resistance R at the fifth charge / discharge initial stage gradually increases when the weight percent concentration of sulfuric acid is 20 wt% or less, and reaches 1.34 Ωcm ^{2 at} 5 wt%.
At 2.5 wt%, it rapidly increases to 1.84 Ωcm ² .

The internal resistance R converges to 1.0 Ωcm ² when the weight percent concentration of sulfuric acid is 20% by weight or more, and becomes almost constant especially when the concentration is 25 to 35% by weight.

This indicates that even if the concentration of sulfuric acid is as high as 25 wt% or more, the extra concentration of the electrolyte does not contribute to the reduction of the internal resistance R at all.

Next, the internal resistance R at the 10,000th constant current charge / discharge is higher than that at the fifth time. In particular,
The increase in the low weight percent concentration region is evident,
% At 1.56 Ωcm ² , and 2.5 wt% at 2.30 Ωcm ²
Ωcm ² .

However, at 20 wt% or more, the amount of increase is very small, but at 25 to 35 wt%, the internal resistance R is almost constant. It does not contribute to the reduction of the resistance R.

From the above results, in the electric double layer capacitor 1 using the sulfuric acid solution as the electrolyte, the electrolyte concentration was 20 to 3
It can be seen that 5 wt% is desirable, and most preferably 25 wt%.

As described above, the electric double layer capacitor 1
, The relationship between the internal resistance R of the electric double layer capacitor 1 and the electrolyte concentration was carefully and carefully examined, and it was found that there was a clear correlation between the relationship between the electrolyte concentration and the internal resistance R.

That is, the carbon electrode 2 and the separator 3
By impregnating the electrolyte with an appropriate electrolyte concentration, the internal resistance R can be minimized and the cost can be minimized. [Fourth Example] Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached.

This example is a modification of the third example described above. Then, similarly to FIG. 1 of the first example described above, the electric double layer capacitor 1 of the non-aqueous solvent liquid organic electrolyte is formed using the carbon electrode 2 and the separator 3, and the internal resistance R
To evaluate.

What differs from the third example is the electrolyte and the charging voltage. That is, an organic electrolyte having a predetermined electrolyte concentration obtained by dissolving a tetraethylammonium boron tetrafluoride electrolyte in a propylene carbonate solvent is used as the electrolyte.

The electrolyte ion concentration here is a molar concentration (symbol M). The charging voltage is 3.5V.

FIG. 5 shows the relationship between the electrolyte concentration and the internal resistance R.

First, the fifth internal resistance R at the beginning of charging and discharging
The increase is remarkable when the electrolyte concentration is 0.9 M or less,
23.0Ωcm ² at 0.6M, 33.1 at 0.5M
It rapidly increases to Ωcm ² .

The internal resistance R gradually decreases when the internal resistance is 0.9 M or more, and is not as convergent as the third example.
Converges to １４14 Ωcm ² .

Here, focusing on the electrolyte concentration of 1.0 M, the internal resistance R is 1.1 M or more, which is 1.0 M or more.
And 1.2M, 4.04% and 6.0M compared to 1.0M.
62% reduction.

This indicates that, unlike the third example, an extra electrolyte having an electrolyte concentration of 1.0 M or more helps to reduce the internal resistance R.

Now, the electrolyte concentrations of 1.1M and 1.M
Further study will be made on the decrease of the internal resistance R at 2M.

These internal resistances R have an electrolyte concentration of 1.0
M is a decrease of 0.9596 and 0.9338, and it is important how much the decrease has an effect on the increase of “power density” and “energy density”.

Although it is case-by-case related to the parts, weight, and configuration of the electric double layer capacitor, it generally falls short of the reciprocals of the internal resistance reduction ratio of 1,042 and 1,071. In particular, it is extremely small with respect to an increase in energy density.

Incidentally, the price of the electric double layer capacitor 1 is defined with respect to the energy density.

In the organic electrolyte, as described above,
In particular, the material cost of the electrolyte is relatively expensive, and is generally considered to be more expensive than other members constituting the electric double layer capacitor 1.

Therefore, for an electrolyte concentration of 1.0 M, a concentration of 0.1 M is required.
The 1M and 0.2M electrolyte gains are costly higher. Of course, the price for the increase will also drop due to the mass production effect.

However, the very small increase in the energy density does not compensate for the extra cost of the electrolyte, and therefore the price defined by the energy density increases. When discussing the electrolyte concentration in terms of price,
It is understood that the electrolyte concentration is desirably 1.0 M or less.

Next, as in the third example, the internal resistance R at the 10,000th constant current charge / discharge increases from the value at the fifth time, and becomes more remarkable when the electrolyte concentration is 0.9 M or less.
27.8Ωcm ² at 0.6M, 43.0 at 0.5M
It rapidly increases to Ωcm ² .

However, when the electrolyte concentration is 0.9 M or more, 5
Similarly to the first time, the internal resistance R converges to 13 to 14 Ωcm ² , and does not change from the tendency at the fifth time at 1.1M or 1.2M.

From the above results, in the electric double layer capacitor 1 using an organic electrolytic solution obtained by dissolving a tetraethylammonium boron tetrafluoride electrolyte in a propylene carbonate solvent, the electrolyte concentration may be 0.9 M or more and 1.0 M or less. It turns out that it is most desirable. (Output Density / Energy Density) The relationship between the internal resistance and the output density and energy density will be described.

The output is the power per unit time.
The unit is W (watt).

Energy is the product of output and time, and its unit is J (joule).

Assuming that the unit of time is s (seconds), 1J = 1W × s = 1Ws.

When the unit of time is h (hour), 1J = 1Ws = 1W × (1 ÷ 3600) h = 0.00027777Wh.

The power density is the power per unit weight. If the unit of weight is kg, the unit of power density is W /
kg.

The energy density is energy per unit weight. When the unit of weight is kg, the unit of energy density is J / kg, Ws / kg, or Wh / kg.
Becomes

Assuming that a capacitor having an output density of P (W / kg) discharges for t (s), the energy density of the discharged electricity is Ps (Ws / kg).

Now, when the capacitor is charged to E '(V: volt) and is discharged at a constant current of I (A: ampere), assuming that the internal resistance of the capacitor is R (Ω: ohm), IR (V: ohm) ) Is caused by the internal resistance.

Therefore, the voltage E (V) of the capacitor taken out is E = E'-IR.

Here, the maximum output Pmax (W) is Becomes That is, reducing the internal resistance R increases the output density.

Now, when the capacitor is charged to E '(V: volt), its energy U' (J) is given by the following equation, assuming that the capacitance of the capacitor is C (F: Farad). ) × C × E ′ × E ′.

Now, when discharging at a constant current of I (A: ampere), the internal resistance R (Ω: ohm) of the capacitor causes
The maximum energy Umax (J) taken out is
At the discharge time t (s), Umax = U′−I × I × R × t. In other words, reducing the internal resistance R increases the energy density.

As described above, reducing the internal resistance R is as follows.
It increases both power density and energy density.

[0105]

As described above, according to the present invention,
Since the appropriate volume of electrolyte was impregnated with respect to the total pore volume of the carbon electrode and the separator, the internal resistance can be minimized, and more than necessary so as not to be expensive. By not impregnating the amount of the electrolytic solution, an electric double layer capacitor with a minimum internal resistance and cost can be manufactured.

Further, according to the present invention, since the electrolyte concentration of the electrolytic solution impregnated in each of the carbon electrode and the separator is appropriately adjusted, the internal resistance can be minimized, and furthermore, it is not necessary to avoid a high price. By not impregnating the electrolyte, an electric double layer capacitor with a minimum internal resistance and cost can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a cell structure of an electric double layer capacitor according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an internal resistance with respect to a total pore volume ratio of a sulfuric acid electrolyte electric double layer capacitor.

FIG. 3 is a characteristic diagram showing an internal resistance with respect to a total pore volume ratio of an organic electrolytic solution electric double layer capacitor according to a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing internal resistance with respect to electrolyte concentration of a sulfuric acid electrolyte electric double layer capacitor according to a third embodiment of the present invention.

FIG. 5 is a characteristic diagram showing internal resistance with respect to electrolyte concentration of an organic electrolytic solution electric double layer capacitor according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric double layer capacitor 2 Carbon electrode 3 Separator 4 Current collector 5 Electrode lead 6 Insulated cell frame

Claims (12)

[Claims] 1. An electric double layer capacitor comprising a carbon electrode and a separator sandwiched between the carbon electrodes impregnated with an electrolytic solution, wherein the energy density or the output density relating to the charge / discharge has a constant value. An electric double layer capacitor, wherein an internal resistance relating to the charge / discharge is set to a predetermined value so as to maintain the charge / discharge. 2. The electric double layer capacitor according to claim 1, wherein a predetermined value of the internal resistance related to the charging and discharging is set to a minimum value. 3. The amount of the electrolytic solution impregnated in the carbon electrode and the separator is quantitatively changed so that an internal resistance relating to the charge and discharge becomes a predetermined value. Item 3. The electric double layer capacitor according to Item 1 or 2. 4. A sulfuric acid electrolytic solution is used as an electrolytic solution impregnated in the carbon electrode and the separator, and the electrolytic solution with respect to the total pore volume obtained by adding the pore volumes of the carbon electrode and the separator to each other. The electric double layer capacitor according to claim 3, wherein when the impregnation amount is a total pore volume ratio, the total pore volume ratio is 0.7 or more. 5. A non-aqueous organic electrolyte obtained by dissolving a tetraethylammonium boron tetrafluoride electrolyte in a propylene carbonate solvent as an electrolytic solution impregnated in the carbon electrode and the separator. When the impregnation amount of the electrolytic solution is defined as the total pore volume ratio with respect to the total pore volume obtained by summing the respective pore volumes, the total pore volume ratio is 0.8 or more. Item 6. An electric double layer capacitor according to Item 3. 6. The electric double layer capacitor according to claim 5, wherein said total pore volume ratio is 0.8 or more and 1.0 or less. 7. The electrolyte concentration of the electrolytic solution impregnated in the carbon electrode and the separator is quantitatively changed so that an internal resistance related to the charge and discharge becomes a predetermined value. 3. The electric double layer capacitor according to 1 or 2. 8. The method according to claim 1, wherein a sulfuric acid electrolytic solution is used as the electrolytic solution impregnated in the carbon electrode and the separator, and the electrolyte concentration of the electrolytic solution is set to 20% by weight or more and 35% by weight or less. The electric double layer capacitor according to claim 7, wherein: 9. A non-aqueous solvent organic electrolyte obtained by dissolving a boron tetrafluoride tetraethylammonium electrolyte in a propylene carbonate solvent as an electrolyte to be impregnated in the carbon electrode and the separator, wherein the electrolyte concentration of the electrolyte is reduced. The electric double layer capacitor according to claim 7, wherein the electric charge is set to 0.9 mol or more. 10. The electric double layer capacitor according to claim 9, wherein the electrolyte concentration of the electrolytic solution is set to 0.9 mol or more and 1.0 mol or less. 11. The electric double layer capacitor according to claim 1, wherein tetrafluoropolyethylene is used as a binder for said carbon electrode. 12. The electric double layer capacitor according to claim 1, wherein a porous and electronically insulating material is used as said separator.