JP2020107659A - Lithium ion capacitor - Google Patents

Abstract

To provide a lithium ion capacitor which allows the density of an active material layer to be increased without causing a disconnection in pressing an electrode, and which enables the uniform pre-doping with lithium ions.SOLUTION: A lithium ion capacitor herein disclosed comprises: electrodes each including a piece of current collector foil and an active material layer; and an electrolyte solution. The piece of current collector foil has through-holes; ceramic particles are filled in the through-holes. The rate of a volume of the ceramic particles to a volume of the through-holes is 0.39 or more and 0.65 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to lithium ion capacitors.

Since the lithium-ion capacitor has excellent output characteristics, it is expected to be applied to a power source for driving a vehicle such as an electric vehicle (EV), a hybrid vehicle (HV) and a plug-in hybrid vehicle (PHV).

Since the lithium ion capacitor can obtain a high cell voltage by lowering the negative electrode potential by doping the negative electrode with lithium ions, the energy density can be improved as compared with the conventional electric double layer capacitor. A typical electrode of a lithium ion capacitor has an active material on a current collector foil having a through hole through which an electrolytic solution can pass so that the entire negative electrode is uniformly doped with lithium ion when predoping with lithium ion. It has a configuration in which layers are provided.

In order to improve the characteristics of a lithium ion capacitor, a technique of filling particles in through holes of a current collector foil is known. For example, in Patent Document 1, resin particles are filled in the through holes of the negative electrode current collector foil, pre-doped with lithium ions, and then the resin particles are melted by heat treatment to close the through holes, thereby rapidly charging and discharging. It is disclosed that a lithium ion capacitor having excellent cycle characteristics with a small capacity decrease even if the above is repeated is obtained. For example, Patent Document 2 discloses that the time required for pre-doping with lithium ions can be shortened by filling boric acid, which is an ion conductive substance, in the through holes of the current collector foil.

JP, 2012-059396, A JP, 2013-206705, A

Since the active material used for the electrode (particularly the positive electrode) of the lithium ion capacitor has a large bulk density, there is a problem that the cell capacity of the electrode is small. As a method of increasing the cell capacity of the electrode, a method of reducing the thickness of the current collector foil and a method of increasing the density of the active material layer of the electrode by a press treatment can be considered. When pressed with a high pressure to increase the density of the active material layer, if the current collector foil is a thin perforated foil, the foil will rupture during pressing due to insufficient strength, and the pressure will be sufficient to stretch the foil. Therefore, there arises a problem that the density of the active material layer is not improved. In addition, there is a problem that the foil stretches and the through holes are closed, and it becomes difficult to pre-dope lithium ions uniformly. Even when the hole diameter is reduced to increase the strength of the current collector foil or the number of through holes is reduced, there is a problem that it is difficult to uniformly perform pre-doping of lithium ions.

Therefore, the present invention aims to provide a lithium ion capacitor capable of improving the density of the active material layer without breaking when the electrode is pressed, and capable of uniformly predoping lithium ions. And

The lithium ion capacitor disclosed herein includes an electrode including a current collector foil and an active material layer, and an electrolytic solution. The current collector foil has a through hole. Ceramic particles are filled in the through holes. The ratio of the volume of the ceramic particles to the volume of the through holes is 0.39 or more and 0.65 or less.
According to such a configuration, a lithium ion capacitor capable of improving the density of the active material layer without breaking when the electrode is pressed and capable of uniformly predoping lithium ions is provided. It

It is a sectional view showing typically an internal structure of a lithium ion capacitor concerning one embodiment of the present invention. It is a figure which shows typically the cross section perpendicular|vertical to the thickness direction of the electrode of the lithium ion capacitor which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that matters other than matters particularly referred to in the present specification and matters necessary for carrying out the present invention (for example, a general configuration and manufacturing process of a lithium ion capacitor that does not characterize the present invention) are It can be understood as a design matter for those skilled in the art based on the conventional technology in the field. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the field. Further, in the following drawings, the same reference numerals are given to the members/sites that have the same effect. Further, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships.

Hereinafter, the present invention will be described in detail by taking a flat rectangular lithium ion capacitor as an example, but the present invention is not intended to be limited to those described in the embodiments.

The lithium ion capacitor 100 shown in FIG. 1 has a configuration in which a flat electrode body 20 and an electrolytic solution (not shown) are contained in a flat prismatic battery case 30. The battery case 30 is provided with a positive electrode terminal 42 and a negative electrode terminal 44 for external connection, and a thin safety valve 36 set to release the internal pressure of the battery case 30 when the internal pressure rises above a predetermined level. There is. Further, the battery case 30 is provided with an injection port (not shown) for injecting the electrolytic solution. The positive electrode terminal 42 is electrically connected to the positive electrode collector plate 42a. The negative electrode terminal 44 is electrically connected to the negative electrode current collector plate 44a. As a material of the battery case 30, for example, a lightweight and highly heat-conductive metal material such as aluminum is used.

As shown in FIG. 1, the electrode body 20 includes a sheet-shaped positive electrode 50 in which a positive electrode active material layer 54 is formed on one surface or both surfaces (here, both surfaces) of a positive electrode current collector foil 52, and one surface of a negative electrode current collector foil 62. Alternatively, it has a form in which a sheet-shaped negative electrode 60 having negative electrode active material layers 64 formed on both surfaces (here, both surfaces) is stacked via a sheet-shaped separator 70.
The electrode body 20 may be a wound electrode body in which one sheet-shaped positive electrode 50 and one sheet-shaped negative electrode are laminated and wound with two separators 70, and a plurality of sheet-shaped It may be a laminated electrode body in which the positive electrode 50, a plurality of sheet-shaped negative electrodes 60, and a plurality of sheet-shaped separators 70 are laminated.
A positive electrode active material layer-free portion 52a (that is, a portion where the positive electrode active material layer 54 is not formed and the positive electrode current collector foil 52 is exposed) is provided at one end of the positive electrode 50. A negative electrode active material layer-free portion 62a (that is, a portion where the negative electrode active material layer 64 is not formed and the negative electrode current collector foil 62 is exposed) is provided at one end of the negative electrode 60. A positive electrode current collector plate 42a and a negative electrode current collector plate 44a are joined to the positive electrode active material layer non-formed portion 52a and the negative electrode active material layer non-formed portion 62a, respectively.

As shown in FIG. 2, the positive electrode 50 has a structure in which a positive electrode active material layer 54 is provided on a positive electrode current collector foil 52.
The material of the positive electrode current collector foil 52 is not particularly limited as long as it is unlikely to cause reaction or elution at the charge/discharge potential, and examples thereof include metal materials such as aluminum, aluminum alloys, stainless steel, and nickel-plated steel. It is aluminum or an aluminum alloy. Aluminum foil is particularly preferable as the positive electrode current collector foil 52.
The positive electrode current collector foil 52 has a through hole 58. Therefore, the electrolytic solution passes through the through holes 58 and moves from the positive electrode active material layer 54 provided on one surface of the positive electrode current collector foil 52 to the positive electrode active material layer 54 provided on the other surface. Is possible. The hole diameter, number, arrangement, etc. of the through holes 58 may be the same as those of the positive electrode current collector foil used in known lithium ion capacitors. The thickness of the positive electrode current collector foil 52 may be the same as that of the positive electrode current collector foil used in a known lithium ion capacitor.

In this embodiment, the through holes 56 of the positive electrode current collector foil 52 are filled with the ceramic particles 58.
Examples of the material of the ceramic particles 58 include alumina (Al ₂ O ₃ ), boehmite, aluminum hydroxide, titania (TiO ₂ ), zirconia (ZrO ₂ ), silicon oxide, magnesium oxide, sodium oxide, and the like. Alumina, titania, and zirconia are preferred. These can be used alone or in combination of two or more.
The shape of the ceramic particles 58 is not particularly limited, and may be spherical, plate-like, amorphous or the like, and preferably spherical.

The ceramic material has a higher strength than the material forming the current collector foil. In other words, the ceramic material is less likely to be deformed by compression than the material forming the current collector foil. Therefore, by filling the through-holes 56 with the ceramic particles 58, the strength of the entire positive electrode current collector foil 52 is improved, the foil stretches and breaks during the pressing process, and the foil stretches and absorbs the pressing pressure. Can be suppressed. As a result, the positive electrode active material layer 54 can be effectively compressed by the press treatment, and the density of the positive electrode active material layer 54 can be increased. Further, the ceramic particles 58 also suppress the expansion of the positive electrode current collector foil 52 and the closing of the through hole 56 during the pressing process, so that the lithium ion to the positive electrode 50 can be supplied to the positive electrode 50 without changing the design of the conventional through hole. Pre-doping can be performed uniformly.
On the other hand, among the conventional techniques, as described above, there are those in which the through holes of the current collector foil are filled with resin particles and boric acid, but the resin particles and boric acid have insufficient strength. It is not possible to obtain the desired effect. In addition, since boric acid is soluble in water and some organic solvents, when the active material layer is prepared using a paste, boric acid may dissolve and flow out from the through holes. Further, in the prior art, the boric acid is densely filled in the through-hole, but in this case, since the ionic conductivity of boric acid is lower than that of the electrolytic solution, the lithium ion is pre-doped uniformly in the negative electrode. It will be difficult.

Here, if the amount of the ceramic particles 58 filled in the through holes 56 is too small, the strength of the entire positive electrode current collector foil 52 cannot be sufficiently improved. Therefore, the ratio of the volume of the ceramic particles 58 to the volume of the through holes 56 is 0.39 or more, and the capacity retention rate is high (the capacity deterioration resistance is high). Therefore, it is preferably 0.44 or more. Further, if the amount of the ceramic particles 58 filled in the through hole 56 is too large, the electrolytic solution is prevented from passing through the through hole 56, and it becomes difficult to uniformly pre-dope the negative electrode 60 with lithium ions. Therefore, the ratio of the volume of the ceramic particles 58 to the volume of the through holes 56 is 0.65 or less.
The “volume of ceramic particles 58 ”is the total volume of all ceramic particles 58 filled in one through hole 56. The “volume of the through holes 56 ”is the volume of the through holes 56 in the state where the ceramic particles 58 are not filled, and therefore the total volume of all the ceramic particles 58 filled in the through holes 56 and the inside of the through holes 56. Is equal to the total volume of the unfilled portion of the ceramic particles 58.
The ratio of the volume of the ceramic particles 58 to the volume of the through holes 56 can be adjusted by appropriately selecting the particle size and the particle shape.

The positive electrode active material layer 54 contains a positive electrode active material.
A preferable example of the positive electrode active material is activated carbon. As the activated carbon, those obtained by carbonizing and activating the following raw materials can be typically used, and known ones used as a positive electrode active material of a lithium ion capacitor may be used.
Examples of the raw material of activated carbon include plant-based raw materials such as wood, wood powder, coconut shell, and pulp waste liquid; fossil-based raw materials such as coal-based pitch, petroleum-based pitch, coke, and coal tar; synthetic resins such as phenolic resin. Can be mentioned.
Examples of the carbonization method include a method of firing the above raw material in an inert gas atmosphere.
Examples of the activation treatment method include a gas activation method such as steam activation and a chemical activation method such as alkali activation.
The average particle diameter of the activated carbon is not particularly limited, but is preferably 20 μm or less, more preferably 1 μm or more and 15 μm or less, still more preferably 1 μm or more and 8 μm or less. In the present specification, the average particle diameter means a 50% volume cumulative diameter D50 obtained from a particle size distribution measured by a laser diffraction method.
The specific surface area of the activated carbon is not particularly limited, but is preferably 800 m ² /g or more and 3000 m ² /g or less, more preferably 1500 m ² /g or more and 2800 m ² /g or less. The specific surface area of activated carbon can be determined by, for example, the BET method.
The content of activated carbon in the positive electrode active material layer 54 is not particularly limited, but is preferably 70% by mass or more, more preferably 75% by mass or more and 98% by mass or less, and further preferably 80% by mass or more and 96% by mass or less.

The positive electrode active material layer 54 may contain components other than the positive electrode active material such as a binder and a conductive material.
As the binder, a polymer binder having no redox decomposition region at the charge/discharge potential can be preferably used. Specific examples thereof include fluororesins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE); cellulose derivatives such as carboxymethyl cellulose (CMC); rubbery polymers such as styrene butadiene rubber (SBR); acrylics. Examples of the binder include polyvinyl alcohol (PVA) and polyethylene oxide.
As the conductive material, carbon black such as acetylene black or Ketjen black; graphite or the like can be used.
The content of the binder in the positive electrode active material layer 54 is not particularly limited, but is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 12% by mass or less, and 2% by mass or more and 10% by mass or less. The following are more preferable.
The content of the conductive material in the positive electrode active material layer 54 is not particularly limited, but is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 12% by mass or less, and 2% by mass or more and 10% by mass. % Or less is more preferable.

The negative electrode 60 has a configuration in which the negative electrode active material layer 54 is provided on the negative electrode current collector foil 62.
Examples of the material of the negative electrode current collector foil 62 include metal materials such as copper, copper alloy, nickel, nickel alloy, stainless steel, and nickel-plated steel, and copper is preferable. Therefore, the copper foil is preferably used as the negative electrode current collector foil 62.

The negative electrode current collector foil 62 has a through hole. Therefore, the electrolytic solution can pass through the through holes and move from the negative electrode active material layer 64 provided on one surface of the negative electrode current collector foil 62 to the negative electrode active material layer 64 provided on the other surface. It is possible. The hole diameter, number, arrangement, etc. of the through holes may be the same as those of the negative electrode current collector foil used in known lithium ion capacitors.

In this embodiment, similarly to the positive electrode current collector foil 52, the through holes of the negative electrode current collector foil 62 are filled with ceramic particles. The ratio of the volume of the ceramic particles 58 to the volume of the through holes 56 is 0.39 or more and 0.65 or less, preferably 0.44 or more and 0.65 or less.
In the present embodiment, the through holes are filled with the ceramic particles in a specific volume ratio in both the positive electrode 50 and the negative electrode 60. However, in the lithium ion capacitor disclosed herein, at least one of the positive electrode and the negative electrode is provided. Only, the through holes may be filled with ceramic particles in a specific volume ratio. Preferably, at least the positive electrode has a configuration in which through holes are filled with ceramic particles in a specific volume ratio.

The negative electrode active material layer 64 contains a negative electrode active material.
As the negative electrode active material, a known negative electrode active material used for negative electrodes for lithium ion capacitors may be used. Examples of the negative electrode active material include carbon materials capable of inserting and extracting lithium, such as graphite, hard carbon, and soft carbon. Further, lithium titanium oxide, silicon oxide or the like can be used as the negative electrode active material.
The content of the negative electrode active material in the negative electrode active material layer 64 is not particularly limited, but is preferably 70% by mass or more, more preferably 80% by mass or more and 99% by mass or less.

The negative electrode active material layer 64 may contain components other than the negative electrode active material such as a conductive material, a binder and a thickener.
Examples of the conductive material include carbon black such as acetylene black and Ketjen black.
Examples of the binder include styrene butadiene rubber (SBR) and the like.
Examples of the thickener include carboxymethyl cellulose (CMC) and the like.
The content of the conductive material in the negative electrode active material layer 64 is not particularly limited, but is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less.
The content of the binder in the negative electrode active material layer 64 is not particularly limited, but is preferably 0.1% by mass or more and 8% by mass or less, more preferably 0.2% by mass or more and 3% by mass or less.
The content of the thickener in the negative electrode active material layer 64 is not particularly limited, but is preferably 0.3% by mass or more and 3% by mass or less, more preferably 0.4% by mass or more and 2% by mass or less. is there.

As the separator 70, a known separator used in lithium ion capacitors may be used.
As the separator 70, for example, a porous sheet made of a resin such as polyethylene (PE), polypropylene (PP), polyester, cellulose or polyamide can be used. Such a porous sheet may have a single-layer structure or a laminated structure of two or more layers (for example, a three-layer structure in which a PP layer is laminated on both surfaces of a PE layer). The thickness of the separator 70 is not particularly limited and is, for example, 10 μm to 100 μm. The average pore size of the separator 70 is not particularly limited and is, for example, 0.01 μm to 5 μm.

As the electrolytic solution, a known one used for a lithium ion capacitor may be used. The electrolytic solution typically contains an electrolyte salt and a non-aqueous solvent. The electrolytic solution may contain additives and the like as necessary.

Lithium salt is preferable as the electrolyte salt, and specific examples thereof include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li(C ₂ F ₅ SO ₂ ) ₂ and LiN(CF ₃ SO ₂ ) _2. Are listed. Among them, high ion conductivity, because it is low resistance, the electrolyte salt relative to the total weight of the electrolyte salt preferably contains LiPF ₆ 80 wt% to 100 wt% or less, it is LiPF ₆ More preferable (that is, 100% by mass of LiPF ₆ ).
Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), cyclic carbonates such as butylene carbonate, dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), methyl propyl carbonate ( Examples include chain carbonates such as MPC) and methyl butyl carbonate (MBC). As the non-aqueous solvent, cyclic esters such as γ-butyrolactone, cyclic sulfones such as sulfolane, cyclic ethers such as dioxolane, chain carboxylic acid esters such as ethyl propionate, chain ethers such as dimethoxyethane, and the like can also be used. it can. These may be used alone or in combination of two or more. In particular, it is preferable to use a mixed solvent containing a cyclic carbonate and a chain carbonate because an electrolytic solution having a low viscosity, a high dissociation degree, and a high ionic conductivity can be obtained.
The concentration of the lithium salt in the electrolytic solution is preferably 0.1 mol/L or more, and more preferably 0.5 mol/L or more and 1.5 mol/L or less.

The manufacturing method of the lithium ion capacitor 100 is not particularly limited. A preferred manufacturing method is a step of producing an electrode, a step of producing the produced electrode, a step of producing an electrode body using a separator, an electrolytic solution, and a prepared lithium ion capacitor using the produced electrode body. And a step of making. In the manufacturing method, the current collector foil has a through hole. In at least one of the positive electrode current collector foil and the negative electrode current collector foil, the through hole is filled with ceramic particles, and the volume ratio of the ceramic particle to the volume of the through hole is 0.39 or more and 0.65. It is as follows. In the step of producing the electrode, a step of applying an electrode paste containing an active material to the current collector foil and a step of drying the applied electrode paste to form an active material layer are performed. At least for the electrode in which the through-holes of the current collector foil are filled with the ceramic particles, the step of performing the press treatment on the formed active material layer is further performed.
Such a method can be performed according to a known method except that a current collector foil in which through holes are filled with ceramic particles in a specific volume ratio is used.

As above, the rectangular lithium ion capacitor 100 including the flat electrode body 20 has been described as an example. However, the configuration of the lithium ion capacitor according to this embodiment is not limited to the above. For example, the lithium ion capacitor according to the present embodiment can be configured as a cylindrical lithium ion capacitor, a laminated lithium ion capacitor, or the like.

According to the lithium ion capacitor 100 configured as above, the density of the active material layer can be improved without breaking when the electrode is pressed, and the lithium ion pre-doping can be performed uniformly. it can.
The lithium ion capacitor 100 can be applied to various applications in which an electricity storage device is used. Suitable applications include a driving power source mounted on vehicles such as electric vehicles (EV), hybrid vehicles (HV), and plug-in hybrid vehicles (PHV).

Examples of the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.

<Example 1>
Activated carbon as a positive electrode active material, polyvinylidene fluoride as a binder, and carbon black as a conductive material were mixed in N-methylpyrrolidone at a predetermined mass ratio to obtain a negative electrode paste.
In addition, an aluminum foil having a thickness of 20 μm having through holes (hole diameter 100 μm) was prepared. Alumina particles were filled into the through holes so that the volume ratio to the total volume of the through holes was 0.39, to prepare a positive electrode current collector foil.
The obtained positive electrode mixture paste was applied to both surfaces of the above positive electrode current collector foil and dried to form a positive electrode active material layer. The total weight of both sides was 10 mg/cm ² . Then, the positive electrode active material layer was pressed to produce a positive electrode.
Natural graphite as a negative electrode active material, carboxymethyl cellulose as a thickener, and styrene-butadiene rubber as a binder were mixed in water at a predetermined mass ratio to obtain a negative electrode paste.
The obtained negative electrode paste was applied to both surfaces of a copper foil having through holes and dried to form a negative electrode active material layer. The total weight of both sides was 12 mg/cm ² . Then, the negative electrode active material layer was pressed to produce a negative electrode. The density of the negative electrode active material layer of this negative electrode was 1.5 g/cm ³ .
Further, a polyolefin porous film having a thickness of 20 μm was prepared as a separator.
An electrode body was produced by stacking 10 positive electrodes, 11 negative electrodes and a separator. A metal Li-coated foil was laminated on one main surface of this electrode body via a separator.
This was accommodated in a case together with the electrolytic solution. The electrolytic solution contained LiPF _{6 in an amount} of 1.0 mol/L in a mixed solvent containing ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 1:1:1. What was dissolved at a concentration was used.
As described above, the lithium ion capacitor of Example 1 was obtained.

<Examples 2 to 5 and Comparative Examples 1 and 2>
As the positive electrode current collector foil, the through holes were filled with the ceramic particles described in Table 1 such that the volume ratio to the volume of the through holes was the value described in Table 1, to prepare the positive electrode current collector foil.
A lithium ion capacitor was produced in the same manner as in Example 1 except that this positive electrode current collector foil was used.

<Comparative example 3>
A lithium ion capacitor was prepared in the same manner as in Example 1 except that the aluminum foil having through holes used in Example 1 was used as it was as the positive electrode current collector foil (that is, the through holes were not filled with ceramic particles). It was made.

<Difference in positive electrode density>
In the production of the lithium ion capacitors of each example and each comparative example, the density of the positive electrode active material layer of the positive electrode produced by pressing was determined. Then, based on the density of the positive electrode active material layer in Comparative Example 3, the difference between the density of the positive electrode active material layer of the positive electrode in each of Examples and Comparative Examples 1 and 2 and the density of the positive electrode active material layer in Comparative Example 3 ( That is, a value obtained by subtracting the density of the positive electrode active material layer in Comparative Example 3 from the density of the positive electrode active material layer of the positive electrode in each Example and Comparative Examples 1 and 2 was obtained. The results are shown in Table 1.

<Fracture during pressing>
In the production of the lithium ion capacitors of each example and each comparative example, the presence or absence of breakage of the positive electrode current collector foil was examined when the positive electrode was press-treated to produce. The results are shown in Table 1.

<Pre-dope uniformity>
After producing the lithium ion capacitors of each example and each comparative example, they were left for 24 hours for pre-doping. The lithium ion capacitor was disassembled, and the negative electrode on the side where the metallic Li coating foil was placed and the negative electrode on the side where the metallic Li coating foil was not placed in the electrode body were taken out. For these two negative electrodes, the amount of pre-doping of lithium ions was measured and compared. If the difference in the pre-doping amount between the two negative electrodes was less than 5%, the result was passed, and if the difference in the pre-doping amount was 5% or more, the test was rejected. The results are shown in Table 1. In Table 1, the pass is indicated by “◯” and the fail is indicated by “x”.

As shown in Table 1, in Examples 1 to 5 in which the through holes of the current collector foil were filled with the ceramic particles in a volume ratio of 0.39 or more and 0.65 or less, the positive electrode density was higher than the standard, and No fracture was observed, and pre-doping could be performed uniformly.
On the other hand, in Comparative Example 1 in which the volume ratio of the ceramic particles to the through holes was less than 0.39, breakage during pressing could be suppressed, but the positive electrode density could not be increased, as compared with Comparative Example 3. It was It is considered that this is because the effect of improving the strength of the collector foil by the ceramic particles was insufficiently obtained.
In Comparative Example 2 in which the volume ratio of the lamic particles to the through holes was more than 0.65, pre-doping could not be performed uniformly. It is considered that this is because the increase in the volume ratio of the ceramic particles significantly hindered the permeation of lithium ions through the through holes.
From the above, according to the lithium ion capacitor disclosed herein, it is possible to improve the density of the active material layer without breaking when the electrode is pressed, and to perform pre-doping of lithium ions uniformly. It turns out that is possible.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

20 electrode body 30 battery case 36 safety valve 42 positive electrode terminal 42a positive electrode current collector plate 44 negative electrode terminal 44a negative electrode current collector plate 50 positive electrode 52 positive electrode current collector foil 52a positive electrode active material layer non-formed portion 54 positive electrode active material layer 56 through hole 58 ceramic particles 60 negative electrode 62 negative electrode current collector foil 62a negative electrode active material layer non-formed portion 64 negative electrode active material layer 70 separator 100 lithium ion capacitor

Claims (1)

A lithium ion capacitor including an electrode having a collector foil and an active material layer, and an electrolyte solution,
The current collector foil has a through hole,
The through holes are filled with ceramic particles,
The ratio of the volume of the ceramic particles to the volume of the through holes is 0.39 or more and 0.65 or less,
Lithium-ion capacitor.

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