JP5868158B2 - Power storage device - Google Patents

Description

  The present invention relates to an electricity storage device having an electrode unit in which a positive electrode sheet and a negative electrode sheet are arranged so as to overlap each other via a sheet-like separator.

In recent years, energy storage devices called hybrid capacitors, which combine the storage principles of lithium ion secondary batteries and electric double layer capacitors, have attracted attention as capacitors for applications that require high energy density and high output characteristics. Yes. As such an electricity storage device, a carbon material capable of inserting and extracting lithium ions is previously occluded and supported (hereinafter sometimes referred to as “doping”) by an electrochemical method to lower the potential. Thus, a lithium ion capacitor having a negative electrode capable of obtaining a high energy density has been proposed (see, for example, Patent Document 1).
In addition, as a lithium ion secondary battery, a pre-doped lithium ion secondary battery in which lithium ions are doped in advance on a negative electrode has been proposed in order to further increase the energy density (see, for example, Patent Document 2). ).

As such an electricity storage device, a lithium ion supply source made of a lithium metal foil is pressure-bonded to a separator disposed between a positive electrode sheet and a negative electrode sheet (see Patent Document 3), lithium. It is known that a lithium supply source made of a metal layer is laminated on the surface of an electrode layer of a negative electrode sheet (see Patent Document 4).
However, the above power storage device has the following problems.
When a lithium metal foil is used as a lithium ion supply source, it is necessary to use a lithium metal foil having a considerably large thickness from the viewpoint of handling. There is a problem that it takes. Moreover, since all the lithium metal foil may not be ionized and may remain as lithium metal, the electrode sheets may be short-circuited by the remaining lithium metal.
On the other hand, in a configuration in which a lithium metal layer is directly laminated on the electrode layer of the negative electrode sheet as a lithium ion supply source, a thin lithium metal layer can be formed, so that lithium ions are doped in a short time. Although it is possible, part of the lithium metal ionizes and solid-phase diffuses into the electrode layer after the lithium metal layer is formed on the electrode layer and before the electrode unit is impregnated with the electrolyte. For this reason, the electrode layer may be deteriorated.

In order to solve such problems, there has been proposed an electric storage device in which lithium metal is vapor-deposited on a separator so that a lithium supply source including a lithium metal layer having a specific thickness is integrally formed on the separator. (For example, refer to Patent Document 5).
According to such an electricity storage device, the ion layer is reliably ionized in a short time, and lithium ions are uniformly doped into the electrode layer of the negative electrode sheet, and the deterioration of the electrode layer due to solid-phase diffusion of lithium ions can be suppressed. It can be done.
However, in the above electricity storage device, since the lithium metal layer is formed in a wide area on the surface of the separator, the electrolyte solution penetrates into the electrode unit composed of the laminate of the positive electrode sheet, the separator, and the negative electrode sheet. As a result, it has been found that it takes a long time for the doping of the electrode layer of the negative electrode sheet to be completed after the electrolyte solution is injected.

Japanese Patent Laid-Open No. 8-1007048 Japanese Patent No. 4015993 JP 2007-173615 A JP 2009-272585 A JP 2011-216600 A

  The present invention has been made based on the circumstances as described above, and the object thereof is to prevent deterioration of each electrode layer of the positive electrode sheet or the negative electrode sheet, and to form lithium ions in each electrode layer in a short time. Is to provide an electricity storage device in which is efficiently doped.

The electricity storage device of the present invention comprises an electrode unit in which a positive electrode sheet and a negative electrode sheet each having an electrode layer formed on a current collector are disposed so as to overlap each other via a sheet-like separator, and an electrolytic solution. An electrical storage device in which lithium ions released from the lithium ion source are doped into the electrode layer by electrochemical contact between the electrode layer and the lithium ion source,
A plurality of film-like lithium ion supply sources are formed integrally with the separator so as to be separated from each other ,
Each of the lithium ion supply sources has a thickness of 1 μm or more and less than 30 μm .

In the electricity storage device of the present invention, each of the lithium ion supply sources is preferably formed by vapor deposition.
Each of the lithium ion supply sources is preferably formed between the electrode layer and the separator .
Moreover, it is preferable that ratio of the sum total of the area of the surface of the said lithium ion supply source with respect to the area of the surface of the electrode layer of the said negative electrode sheet is 0.6-0.95.
Moreover, it is preferable that it is comprised as a lithium ion capacitor.

According to the electricity storage device of the present invention, the plurality of film-like lithium ion supply sources are formed in the separator so as to be separated from each other, so that the electrolyte solution is inhibited from penetrating into the electrode unit. Therefore, the lithium ion supply source is reliably ionized in a short time, and the negative electrode sheet and / or the electrode layer of the positive electrode sheet is efficiently doped with lithium ions in a short time. Further, since the lithium ion supply source is formed integrally with the separator, it can be easily handled even if the thickness is small, so that high productivity can be obtained.
In addition, the lithium ion supply source is not directly formed on the electrode layer, and the electrode layer of the negative electrode sheet and / or the positive electrode sheet is in contact with the lithium ion supply source when the electrode unit is assembled. By rapidly impregnating the electrode unit with the electrolytic solution after assembling the electrode unit, it is possible to prevent deterioration of the electrode layer due to, for example, solid phase diffusion of lithium ions in the dry room.

It is an explanatory top view which shows an example of a structure of the lithium ion capacitor which concerns on this invention. It is sectional drawing for description which shows the XX cross section in the lithium ion capacitor shown in FIG. It is a top view which shows the separator in which the lithium supply source was formed.

Hereinafter, the embodiment of the present invention includes a so-called stacked electrode unit in which a plurality of positive electrode sheets and a plurality of negative electrode sheets are alternately stacked via separators, and the electrode units are stacked on each other. A case where the present invention is applied as a lithium ion capacitor having a configuration accommodated in an exterior container made of the exterior laminate film will be described in detail.
In the present invention, the “positive electrode” means a pole on the side where a current flows out during discharging and a current flows in during charging, and the “negative electrode” refers to a current flowing in during discharging. This means the pole on the side where current flows out.

FIG. 1 is an explanatory plan view showing an example of the configuration of a lithium ion capacitor according to the present invention, and FIG. 2 is an explanatory sectional view showing an XX cross section of the lithium ion capacitor shown in FIG.
In this lithium ion capacitor 10, the outer packaging films 12 and 13 that are superposed on each other are hermetically joined to each other at a joint portion 14 formed on each outer peripheral edge portion, and the outer packaging container 11 is formed in the outer packaging container 11. The electrode unit 20 formed by laminating a plurality of positive electrode sheets 21 and a plurality of negative electrode sheets 24 via a sheet-like separator 27 is accommodated and filled with an electrolytic solution. At one end and the other end of the outer casing 11, the positive electrode terminal 18 and the negative electrode terminal 19 are sandwiched between the joint portions 14 of the outer films 12 and 13, respectively, and one end is located in the outer casing 11. The other end is provided so as to protrude to the outside of the outer casing 11. The positive electrode current collector 22 in the plurality of positive electrode sheets 21 and the negative electrode current collector 25 in the negative electrode sheet 24 constituting the electrode unit 20 are respectively connected to the positive electrode terminals via metal sheet-like lead members 31 and 32. 18 and the negative electrode terminal 19 are electrically connected.
In the illustrated example, a sheet for electrically connecting the positive electrode terminal 18 and each of the positive electrode current collectors 22 of the positive electrode sheet 21 to one end portion of the positive electrode terminal 18 located in the outer casing 11. Each of the terminal joining end portions 31a of the shaped lead member (hereinafter also referred to as “lead member for positive electrode”) 31 is fixed by welding or the like in a bundled state. Further, a sheet-like lead member for electrically connecting the negative electrode terminal 19 and each of the negative electrode current collectors 25 of the negative electrode sheet 24 to one end portion of the negative electrode terminal 19 located in the outer casing 11. (Hereinafter, also referred to as “negative electrode lead member”.) Each of the terminal joining end portions 32a in 32 is fixed by welding or the like in a bundled state.

[Electrode unit]
In the electrode unit 20 constituting the lithium ion capacitor 10, as shown in FIG. 2, a plurality of positive electrode sheets 21 each having a positive electrode layer 23 formed on both surfaces of a positive electrode current collector 22, and a negative current collector, respectively. A plurality of negative electrode sheets 24 each having a negative electrode layer 26 formed on one surface or both surfaces of the body 25 are alternately laminated so that the positive electrode layers 23 and the negative electrode layers 26 face each other with a separator 27 interposed therebetween. ing.
In the example of this figure, the electrode sheet of the outermost layer (the uppermost layer and the lowermost layer in FIG. 2) of the electrode unit 20 is a negative electrode sheet 24. In the negative electrode sheet 24 of the outermost layer, a negative electrode current collector 25 is used. The negative electrode layer 26 is formed on one surface, and the negative electrode layer 26 is formed on both surfaces of the negative electrode current collector 25 in other negative electrode sheets 24 (other than the negative electrode sheet 24 constituting the outermost layer). ing. A separator 27 is disposed on the upper surface of the uppermost negative electrode sheet 24 and the lower surface of the lowermost negative electrode sheet 24.

[Current collector]
As the positive electrode current collector 22 and the negative electrode current collector 25 (hereinafter also referred to as “electrode current collector”) in the positive electrode sheet 21 and the negative electrode sheet 24, those made of metal foil are used. However, when doping lithium ions released from a lithium ion supply source, which will be described later, into the negative electrode layer 26 in the negative electrode sheet 24 and / or the positive electrode layer 23 in the positive electrode sheet 21, a plurality of penetrations that penetrate the front and back surfaces It is preferable to use a material made of a porous material having pores. Examples of the form of the porous material include punching metal, foam, or porous foil having through holes formed by etching or electrolytic etching.
The shape of the through hole of the electrode current collector can be set to a circle, a polygon such as a rectangle, or any other appropriate shape.
Moreover, it is preferable that the thickness of an electrode electrical power collector is 1-100 micrometers from a viewpoint of intensity | strength and weight reduction.

In the electrode current collector, the average pore diameter of the plurality of through holes is preferably 300 μm or less, more preferably 10 to 100 μm.
When the average hole diameter of the through holes in the electrode current collector is excessive, the amount of lithium ions doped in the positive electrode layer 23 and the negative electrode layer 26 constituting the positive electrode sheet 21 and the negative electrode sheet 24 is sufficient. The uniformity may not be obtained, and the durability may deteriorate due to unevenness in the ion concentration in the positive electrode layer 23 and the negative electrode layer 26.

In the electrode current collector, the porosity is preferably 30 to 70%, more preferably 40 to 60%.
Here, the porosity is calculated by the following mathematical formula (1).
Formula (1):
Porosity = [1− (mass of current collector / true specific gravity of current collector) / (apparent volume of current collector)] × 100

As a material constituting the negative electrode current collector 25, stainless steel, copper, nickel, or the like can be used.
Moreover, as a material which comprises the positive electrode electrical power collector 22, aluminum, stainless steel, etc. can be used.

  By using such a specific porous material as an electrode current collector, lithium ions released from a lithium ion supply source, which will be described later, can freely pass through the through holes of the electrode current collector from the front side to the back side Since it can move, lithium ions can be uniformly doped in the negative electrode layer 26 in the negative electrode sheet 24 and / or the positive electrode layer 23 in the positive electrode sheet 21 by the lithium ion supply source. In addition, when a porous material is used as all electrode current collectors, lithium ions can move freely between the electrodes, and thus can be more uniformly doped.

(Electrode layer)
The negative electrode layer 26 in the negative electrode sheet 24 contains a negative electrode active material capable of reversibly carrying lithium ions, that is, doped and undoped, and the positive electrode layer in the positive electrode sheet 21. 23 contains a positive electrode active material capable of reversibly supporting lithium ions and / or anions such as tetrafluoroborate.

The thickness of the negative electrode layer 26 in the negative electrode sheet 24 is designed in consideration of the balance with the thickness of the positive electrode layer 23 in the positive electrode sheet 21 so as to ensure a sufficient energy density for the obtained lithium ion capacitor 10. However, in the case of being formed on one surface of the negative electrode current collector 25 from the viewpoint of the output density, energy density, industrial productivity, and the like of the obtained lithium ion capacitor, it is usually 15 to 200 μm, preferably 20 to 100 μm. .
Further, the thickness of the positive electrode layer 23 in the positive electrode sheet 21 is designed in consideration of the balance with the thickness of the negative electrode layer 26 in the negative electrode sheet 24 so as to ensure a sufficient energy density in the obtained lithium ion capacitor 10. However, from the viewpoint of the output density, energy density, industrial productivity, and the like of the obtained lithium ion capacitor 10, when formed on one surface of the positive electrode current collector 23, usually 15 to 300 μm, preferably 20 to 20 μm. 200 μm.

[Negative electrode active material]
The negative electrode active material contained in the negative electrode layer 26 in the negative electrode sheet 24 is a substance that can reversibly carry, that is, dope and dedope, lithium ions.
As such a negative electrode active material, for example, a heat-treated product of graphite, non-graphitizable carbon, and aromatic condensation polymer having a hydrogen atom / carbon atom ratio (hereinafter referred to as “H / C”). A polyacene organic semiconductor (hereinafter referred to as “PAS”) having a polyacene skeleton structure of 0.50 to 0.05 can be suitably used.

[Positive electrode active material]
The positive electrode active material contained in the positive electrode layer 23 in the positive electrode sheet 21 is a substance that can reversibly carry lithium ions and / or anions such as tetrafluoroborate.
As such a positive electrode active material, for example, a polyacene skeleton having a hydrogen atom / carbon atom ratio of 0.50 to 0.05, which is a heat-treated product of activated carbon, a conductive polymer, and an aromatic condensation polymer A polyacene organic semiconductor (PAS) having a structure can be used.

[Method of forming electrode layer]
In the lithium ion capacitor 10 according to the present invention, the negative electrode layer 26 in the negative electrode sheet 24 is formed on the negative electrode current collector 25 using a material containing the above negative electrode active material. A publicly known method can be used without being specified.
Specifically, a slurry in which a negative electrode active material powder, a binder, and a conductive powder used as needed is dispersed in an aqueous medium or an organic solvent is prepared, and this slurry is formed on the surface of the negative electrode current collector 25 (one surface). Alternatively, the negative electrode layer 26 may be applied by drying on the both surfaces of the negative electrode current collector 25 or by drying the slurry in advance into a sheet shape and attaching the resulting molded product to the surface (one surface or both surfaces) of the negative electrode current collector 25. Can be formed.
Here, examples of the binder used for preparing the slurry include rubber-based binders such as SBR, fluorine-based resins such as polytetrafluoroethylene and polyvinylidene fluoride, and thermoplastic resins such as polypropylene and polyethylene.
Moreover, as an electroconductive powder used as needed, acetylene black, a graphite, a metal powder etc. are mentioned, for example.

In the case of forming the negative electrode layer 26 by applying a slurry on the negative electrode current collector 25, the slurry may be applied directly on the negative electrode current collector 25, or before applying the slurry to the negative electrode current collector 25. In addition, at least a part of the through holes in the negative electrode current collector 25 may be closed using a conductive material that does not easily drop off.
Thus, by forming the negative electrode layer 26 on the negative electrode current collector 25 in a state in which at least a part thereof is blocked, the productivity of the electrode sheet can be improved, and the negative electrode current collector 25 to the negative electrode layer can be improved. It is possible to prevent or suppress a decrease in the reliability of the lithium ion capacitor 10 that is caused by the drop of 26.

  Moreover, the positive electrode layer 22 in the positive electrode sheet 21 can be formed by the same method as the negative electrode layer 26 in the negative electrode sheet 24 using a material containing the positive electrode active material.

[Separator]
As the separator 27, a porous body having low electrical conductivity having a continuous air hole that is durable to an electrolytic solution, a positive electrode active material, or a negative electrode active material and can be impregnated with the electrolytic solution can be used.
As the material of the separator 27, cellulose (paper), polyethylene, polypropylene, polyethylene-polypropylene copolymer, cellulose / rayon, thermoplastic resin such as engineer plastic / super engineer plastic, glass fiber, and other known materials should be used. Can do. Among these, polyethylene, polypropylene, polyethylene-polypropylene copolymer, and cellulose / rayon are preferable from the viewpoint of durability and economy.
Moreover, the thickness of the separator 27 is not particularly limited, but usually about 10 to 50 μm is preferable. Further, the length (L) × width (W) of the separator 27 can be appropriately changed depending on the design.

[Lithium ion source]
In the lithium ion capacitor 10 according to the present invention, as shown in FIG. 3, a plurality of film-like lithium ion supply sources 28 are integrally formed on the separator 27 so as to be separated from each other. In the illustrated example, a large number of rectangular lithium ion supply sources 28 are arranged on the separator 27 so as to be arranged in a lattice pattern.

  The lithium ion supply source 28 is preferably formed so as to be positioned between the positive electrode layer 22 or the negative electrode layer 26 and the separator 27, and is positioned between the negative electrode layer 26 and the separator 27. More preferably, it is formed, and it is particularly preferable that the lithium ion supply source 28 is in contact with the negative electrode layer 26 of the negative electrode sheet 24. With such a configuration, each of the positive electrode layer 22 or the negative electrode layer 26 can be efficiently doped with lithium ions. Further, when a porous foil is used for the negative electrode current collector 25 and / or the positive electrode current collector 22, at least one surface may be in contact with the lithium ion supply source.

The thickness of the lithium ion supply source 28 is preferably 1 μm or more and less than 30 μm, more preferably 1 μm or more and less than 15 μm. When the thickness of the lithium ion supply source 28 is less than 1 μm, the negative electrode layer 26 of the negative electrode sheet 24 is not doped with a sufficient amount of lithium ions, making it difficult to obtain a high-capacity capacitor. On the other hand, when the thickness of the lithium ion supply source 28 is 30 μm or more, the surface of the negative electrode layer 26 by direct contact between the negative electrode layer 26 of the negative electrode sheet 24 and the lithium metal constituting the lithium ion supply source 28. Due to the increase in resistance, etc., all the lithium ion supply sources 28 may not be ionized and remain as lithium metal. In this case, the capacity of the obtained capacitor may be reduced, or the positive electrode sheet 21 and the negative electrode sheet 24 may be short-circuited by the remaining lithium metal.
The specific thickness of the lithium ion supply source 28 is appropriately determined in consideration of the amount of lithium ions doped in the negative electrode sheet 24 and the surface area of the negative electrode layer 26 of the negative electrode sheet 24.

  The amount of lithium metal constituting the lithium ion supply source 28 is doped with lithium ions so that the potential of the positive electrode sheet is 2.0 V or less when the positive electrode sheet 21 and the negative electrode sheet 24 are short-circuited. It is preferable to set the amount.

Further, the total surface area of the lithium ion supply source 28 formed in one separator 27 is 0.6 to 0.95 in a ratio to the surface area of one negative electrode layer 26 in the negative electrode sheet 24. Is more preferable, and 0.8 to 0.95 is more preferable. When the value of this ratio is too small, it is difficult to uniformly supply lithium ions to the entire negative electrode layer 26 in the negative electrode sheet 24, and the characteristics of the obtained capacitor may be deteriorated. On the other hand, when the value of this ratio is excessive, the lithium metal that protrudes from the surface of the negative electrode layer 26 of the negative electrode sheet 24 remains as it is without being ionized. May cause problems such as internal short circuit.
The area of the surface of the lithium ion source 28 is not particularly limited, for example, when the electrostatic capacity of the lithium ion capacitor of 250F is preferably 100～1000Cm ^2, more preferably 200-600 ² It is.

The method for integrally forming the lithium ion supply source 28 on the separator 27 is not particularly limited, but it is preferable to use a vapor deposition method, whereby the lithium ion supply source 28 having a required thickness is reliably formed. be able to.
Further, in order to form each of the lithium ion supply sources 28 apart from each other, lithium metal is deposited on the separator 27 through a mask having an opening that matches the shape of the target lithium ion supply source 28. Good.

[Positive electrode terminal and negative electrode terminal]
As a material constituting the positive electrode terminal 18, for example, aluminum or stainless steel can be used.
Moreover, as a material which comprises the negative electrode terminal 19, copper, nickel, a sun teles etc. can be used, for example.

[Exterior container]
The outer packaging container 11 is mutually connected at a joint portion 14 formed over the entire circumference of each outer peripheral edge in a state where one outer packaging film 12 made of a rectangular laminate film and the other outer packaging film 13 are overlapped with each other. The outer container 11 is configured to be hermetically bonded, and an accommodation space for accommodating the electrode unit 20 and filling the electrolyte is formed inside the outer container 11.
In the example shown in the drawing, a drawing process is applied to the central portion of one of the exterior films 12, thereby forming an accommodation space inside the exterior container 11.

As a laminate film constituting one exterior film 12 and the other exterior film 13, for example, three layers in which a polypropylene (hereinafter referred to as “PP”) layer, an aluminum layer, a nylon layer, and the like are laminated in this order from the inside. What has a structure can be used.
The vertical and horizontal dimensions of one exterior film 12 and the other exterior film 13 are appropriately selected according to the dimensions of the electrode unit 20 to be accommodated. For example, the longitudinal dimension is 40 to 200 mm, and the lateral dimension is 60. ~ 300 mm.

[Electrolyte]
As the electrolytic solution, an aprotic organic solvent electrolyte solution of a lithium salt is preferably used.
As the lithium salt constituting the electrolyte, any lithium salt can be used as long as it is capable of transporting lithium ions, does not cause electrolysis even under high voltage, and lithium ions can exist stably. Specific examples thereof include LiClO ₄ , Examples include LiAsF ₆ , LiBF ₄ , LiPF ₆ , and Li (C ₂ F ₅ SO ₂ ) ₂ N.
Specific examples of the aprotic organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, acetonitrile, dimethoxyethane, tetrahydrofuran, dioxolane, methylene chloride, sulfolane and the like. These aprotic organic solvents can be used alone or in admixture of two or more.

Such a lithium ion capacitor 10 can be manufactured as follows, for example.
First, the electrode unit 20 is disposed at the central portion on the other exterior film 13, and the positive electrode current collector 22 and the negative electrode current collector 25 in the electrode unit 20 are connected to the positive electrode terminal via the sheet-like lead portions 31 and 32. 18 and the negative electrode terminal 19 are electrically connected. Then, one exterior film 12 is overlaid on the electrode unit 20 to which the positive electrode terminal 18 and the negative electrode terminal 19 are electrically connected, and in this state, the outer periphery of one exterior film 12 and the other exterior film 13 After heat-sealing the three sides in the part, an electrolyte is injected between the one exterior film 12 and the other exterior film 13, and further, the outer periphery of the one exterior film 12 and the other exterior film 13 is not yet formed. The outer container 11 is formed by thermally fusing one side of the fusion, and thus the lithium ion capacitor 10 is obtained.
And in the lithium ion capacitor 10 obtained in this way, by leaving it for an appropriate time, by the electrochemical contact between the negative electrode sheet 24 and / or the positive electrode sheet 21 and the lithium ion supply source 28, Lithium ions released from the lithium ion supply source 28 are doped into the negative electrode sheet 24 and / or the positive electrode sheet 21.

According to the lithium ion capacitor of the present invention, the plurality of film-like lithium ion supply sources 28 are formed in the separator 27 so as to be separated from each other, thereby preventing the electrolyte solution from penetrating into the electrode unit 20. Therefore, the lithium ion supply source 28 is reliably ionized in a short time, and the lithium ion source 26 and / or the positive electrode layer 23 of the positive electrode sheet 21 are quickly ionized in a short time. Is efficiently doped. Further, since the lithium ion supply source 28 is formed integrally with the separator 27, it can be easily handled even if it has a small thickness, so that high productivity can be obtained.
Further, the lithium ion supply source 28 is not directly formed on the positive electrode layer 23 and the negative electrode layer 26, and the negative electrode layer 26 and / or the positive electrode layer 23 and the lithium ion supply when the electrode unit 20 is assembled. Since the electrode 28 is in contact with the source 28, the electrode unit 20 is rapidly impregnated with an electrolyte after the electrode unit 20 is assembled. For example, the negative electrode layer 26 by solid phase diffusion of lithium ions in the dry room and / or Alternatively, the deterioration of the positive electrode layer 23 can be prevented.

As mentioned above, although an example at the time of implementing this invention as a lithium ion capacitor was demonstrated, this invention is not limited to said embodiment, A various change can be added. For example, the lithium ion supply source 28 is not limited to a rectangular shape, and may have a circular shape, a polygonal shape, or other shapes. Moreover, not all lithium ion supply sources 28 may have the same shape, and the above shapes may be combined. Further, each of the lithium ion sources 28 may be arranged irregularly.
Further, the electrode unit 20 is not limited to a stacked structure as shown in FIG. 2, and may have a wound structure or another structure.
Further, the electricity storage device of the present invention is not limited to a lithium ion capacitor, and can be suitably applied to an electric double layer capacitor and a lithium ion secondary battery.

<Example 1>
According to the configuration shown in FIGS. 1 to 3, a lithium ion capacitor was manufactured as follows. (1) Production of negative electrode sheet:
A slurry for negative electrode was prepared by adding 100 parts by mass of PAS powder and 10 parts by mass of polyvinylidene fluoride powder to 80 parts by mass of N-methylpyrrolidone and dissolving / dispersing it. This negative electrode slurry was intermittently applied with a die coater and dried on both sides of a negative electrode current collector made of copper expanded metal (manufactured by Nippon Metal Industry Co., Ltd.) having a thickness of 32 μm and a porosity of 50%. An electrode layer having a vertical and horizontal dimension of 65 mm × 70 mm was formed by pressing the resulting coating film. Then, the portion where the negative electrode layer is not formed (hereinafter referred to as “uncoated portion” for the negative electrode sheet composite) is cut into a size of 65 mm × 85 mm so that the vertical and horizontal dimensions are 65 mm × 15 mm. As a result, a negative electrode sheet composite having a structure in which a lead member made of an uncoated portion was continuously formed integrally with one end of the negative electrode sheet made of a coated portion was produced.

(2) Production of positive electrode sheet:
A positive electrode slurry is prepared by adding and dispersing 100 parts by mass of activated carbon powder having a specific surface area of 1950 m ² / g, 10 parts by mass of acetylene black, 7 parts by mass of an acrylic binder, and 4 parts by mass of carboxymethyl cellulose in water. did.
On the other hand, a non-aqueous carbon-based conductive paint (manufactured by Nippon Atsson Co., Ltd.) is formed on both surfaces of a positive electrode current collector made of aluminum expanded metal (manufactured by Nippon Metal Industry Co., Ltd.) having a thickness of 35 μm and a porosity of 50%. EB-815) was intermittently applied with a die coater and dried to form a base layer having a vertical and horizontal dimension of 60 mm × 65 mm. The total thickness of the positive electrode current collector and the underlayer formed on both surfaces thereof was 52 μm, and the holes of the positive electrode current collector material were closed by the underlayer.
Next, the prepared slurry for positive electrode is intermittently coated with a die coater on both sides of the base layer formed on the positive electrode current collector material and dried, and by pressing the obtained coating film, An electrode layer having vertical and horizontal dimensions of 60 mm × 65 mm was formed. The portion where the conductive layer and the positive electrode layer are formed (hereinafter referred to as “coating portion” for the positive electrode sheet composite) is 60 mm × 65 mm, and the portion where the conductive layer and the positive electrode layer are not formed (hereinafter referred to as the positive electrode) The electrode sheet composite is cut to a size of 60 mm × 80 mm so that the “uncoated part” is 60 mm × 15 mm, so that an uncoated part is formed on one end of the positive electrode sheet made of the coated part. A positive electrode sheet composite having a structure in which lead members made of the layers were integrally formed continuously was produced.

(3) Production of a separator with a lithium ion supply source formed:
Sixteen separators made of cellulose / rayon mixed nonwoven fabric each having a vertical and horizontal dimension of 68 mm × 91 mm and a thickness of 35 μm are prepared, and 1 cm × 1 cm rectangular openings are formed in a lattice shape with a pitch of 10.66 mm on one side of each separator. A mask formed with a pattern is placed, and lithium metal is deposited on one surface of the separator by a vacuum deposition method, thereby forming a film-like film made of lithium metal having a vertical and horizontal dimension of 1 cm × 1 cm and an average thickness of 10 μm. A number of lithium ion sources were formed according to a grid pattern with a pitch of 10.66 mm. The ratio of the total area of the surface of the lithium ion supply source in contact with the negative electrode layer to the area of the surface of the negative electrode layer of the negative electrode sheet was 0.88.

(4) Production of electrode unit:
First, 7 positive electrode sheet composites, 8 negative electrode sheet composites, and 16 separators on which a lithium ion supply source is formed are used to apply a positive electrode composite sheet and a negative electrode sheet composite to respective coating parts. The separators, the negative electrode sheet composite, the separator, and the positive electrode sheet composite are stacked in this order, and the four sides of the stack are fixed with tape so that the uncoated parts are opposite and do not overlap. As a result, an electrode unit was produced. At this time, each of the lithium ion supply sources was positioned between the negative electrode layer and the separator in the negative electrode sheet, and the separator was disposed in contact with the negative electrode layer.
And the front-end | tip part of each uncoated part of the seven positive electrode sheet composites of the produced electrode unit was bundled, and a sealant film was heat-sealed to the seal part in advance. Width 50 mm, length 50 mm, thickness 0 A 2 mm positive electrode terminal made of aluminum was overlapped and ultrasonically welded. On the other hand, the tip portion of the uncoated portion and the tip portion of the lithium ion supply member of each of the eleven negative electrode sheet composites of the electrode unit are bundled, and a sealant film is heat-sealed to the seal portion in advance. Copper negative electrode terminals having a thickness of 30 mm and a thickness of 0.2 mm were stacked and resistance-welded.
As described above, an electrode unit in which the positive electrode terminal and the negative electrode terminal were electrically connected to the positive electrode current collector and the negative electrode current collector via the sheet-like lead member was produced.

(5) Manufacture of lithium ion capacitors:
First, one exterior film (bonding) whose dimensions are 90 mm (vertical width) × 117 mm (horizontal width) × 0.15 mm (thickness) and whose central portion has been subjected to drawing processing of 70 mm (vertical width) × 97 mm (horizontal width) The width of the outer peripheral edge part which becomes a part was 10 mm), and the other exterior film having a dimension of 90 mm (vertical width) × 117 mm (horizontal width) × 0.15 mm (thickness) was produced.
Next, an electrode unit in which a lithium ion supply member is provided at the center position on the other exterior film and the positive electrode terminal and the negative electrode terminal are connected is connected to the other end of each of the positive electrode terminal and the negative electrode terminal. Each of the sheet-like lead members that protrude outward from the end of the outer film and are connected to one end of the positive electrode terminal and the negative electrode terminal are located on the inner side of the end of the other outer film. This electrode unit is overlaid with one exterior film, and the other exterior film and the outer periphery of one exterior film are heated on three sides (including the two sides from which the positive electrode terminal and the negative electrode terminal protrude). Fusing was performed to form a joint having a width of 10 mm.
Next, after injecting an electrolyte between one exterior film and the other exterior film, the other side of the outer peripheral edge of one exterior film and the other exterior film is heat-sealed to form a joint portion having a width of 10 mm. Formed.
Here, in the production of the electrode unit, the lithium ion supply source formed on the separator is brought into contact with each surface of the electrode layer formed on one surface and the other surface of the negative electrode current collector in the negative electrode sheet, and then the electrode The time until the unit was immersed in the electrolytic solution was 1 hour.
After manufacturing this lithium ion capacitor, the presence or absence of lithium metal constituting the lithium ion supply source was analyzed over time. As a result, it was found that the compatibility with the electrolytic solution was high and the lithium metal layer disappeared in 18 hours. confirmed.
When the characteristics of the lithium ion capacitor were examined, the capacitance was 260 F, the energy density was 19.4 Wh / L, and the internal resistance was 7.0 mΩ.

<Comparative example 1>
Instead of forming a lithium ion supply source by depositing lithium metal on the separator by a vacuum evaporation method, a lithium foil having a thickness of 100 μm is cut and bonded to a copper expanded metal having a thickness of 40 μm, thereby collecting a lithium electrode. A lithium ion supply member having a configuration in which a plurality of lithium ion supply sources having a vertical and horizontal dimension of 61 mm × 66 mm (ratio of the surface area to the surface area of the electrode layer of the negative electrode sheet 0.88) are pressure-bonded on an electric body A lithium ion capacitor was prepared in the same manner as in Example 1 except that this lithium ion supply member was placed on the electrode unit so as to face the negative electrode layer.

After manufacturing this lithium ion capacitor, the presence or absence of lithium metal constituting the lithium ion supply source was analyzed over time, and it was confirmed that it took 4 days for the lithium metal to disappear. Compared with Example 1, it was confirmed that productivity was inferior.
When the characteristics of the lithium ion capacitor were examined, the capacitance was 250 F, the energy density was 19.2 Wh / L, and the internal resistance was 7.3 mΩ.

<Comparative example 2>
Instead of forming a lithium ion source by depositing lithium metal on the separator by a vacuum deposition method, through a mask in which a 1 cm × 1 cm rectangular opening is formed with a grid pattern with a pitch of 10.66 mm, By depositing lithium metal directly on the negative electrode layer by a vacuum deposition method, a large number of lithium ion sources in the form of lithium metal having a vertical and horizontal dimension of 1 cm × 1 cm and an average thickness of 10 μm on the surface of the negative electrode layer Was formed according to a grid pattern with a pitch of 10.66 mm, and a lithium ion capacitor was produced in the same manner as in Example 1.
Here, the ratio of the total area of the surface of the lithium ion source formed on the negative electrode layer to the area of the surface of the negative electrode layer of the negative electrode sheet was 0.88.
The time from when the lithium ion supply source was formed on the surface of the electrode layer of the negative electrode sheet until the electrode unit was immersed in the electrolyte was 3 hours.

After manufacturing this lithium ion capacitor, the presence or absence of lithium metal constituting the lithium ion supply source was analyzed over time, and it was confirmed that the lithium metal disappeared in 26 hours.
When the characteristics of the lithium ion capacitor were examined, the capacitance was 230 F, the energy density was 18.6 Wh / L, and the internal resistance was 9.3 mΩ.
In the lithium ion capacitor according to Comparative Example 2, since lithium metal was deposited on the surface of the negative electrode layer, the lithium ions were solid-phase diffused into the negative electrode active material, resulting in deterioration of the negative electrode layer. Compared with 1, it is considered that the capacitance decreased and the internal resistance increased.

<Comparative Example 3>
Other than having formed a large number of lithium ion sources in the form of lithium metal with a vertical and horizontal dimension of 61 mm x 66 mm and a thickness of 10 μm by depositing lithium metal on the separator without using a mask by vacuum deposition Produced a lithium ion capacitor in the same manner as in Example 1.
Here, the ratio of the total area of the surface of the lithium ion source formed on the negative electrode layer to the area of the surface of the negative electrode layer of the negative electrode sheet was 0.88.
Further, in the production of the electrode unit, the time from when the lithium ion supply source formed on the separator is brought into contact with the surface of the negative electrode layer of the negative electrode sheet until the electrode unit is immersed in the electrolytic solution is 1 hour. there were.

After manufacturing this lithium ion capacitor, the presence or absence of lithium metal constituting the lithium ion supply source was analyzed over time, and it was confirmed that the lithium metal disappeared in 24 hours.
The characteristics of the lithium ion capacitor were examined. The capacitance was 245 F, the energy density was 19.0 Wh / L, and the internal resistance was 7.2 mΩ.
In the lithium ion capacitor according to the comparative example 3, the lithium ion supply source formed in the separator prevents the electrolyte solution from penetrating into the electrode unit. It is thought that the time until the process increased and the internal resistance increased slightly.

DESCRIPTION OF SYMBOLS 10 Lithium ion capacitor 11 Exterior container 12, 13 Exterior film 14 Joint part 18 Positive electrode terminal 19 Negative electrode terminal 20 Electrode unit 21 Positive electrode sheet 22 Positive electrode collector 23 Positive electrode layer 24 Negative electrode sheet 25 Negative electrode collector 26 Negative electrode Electrode layer 27 Separator 28 Lithium ion supply source 31, 32 Sheet-like lead member 31a, 32a Terminal joining end

Claims (5)

Each of the positive electrode sheet and the negative electrode sheet each having an electrode layer formed on a current collector includes an electrode unit disposed so as to overlap with a sheet-like separator interposed therebetween, and an electrolyte solution. An electrical storage device in which lithium ions released from the lithium ion source are doped into the electrode layer by electrochemical contact with the ion source,
A plurality of film-like lithium ion supply sources are formed integrally with the separator so as to be separated from each other ,
Each of the lithium ion supply sources has a thickness of 1 μm or more and less than 30 μm .   The power storage device according to claim 1, wherein each of the lithium ion supply sources is formed by vapor deposition.   Each of the said lithium ion supply source is formed between the said electrode layer and the said separator, The electrical storage device of Claim 1 or Claim 2 characterized by the above-mentioned. 4. The ratio of the total area of the surface of the lithium ion supply source to the area of the surface of the electrode layer of the negative electrode sheet is 0.6 to 0.95 . 5. The electricity storage device described in 1. The power storage device according to any one of claims 1 to 4, wherein the power storage device is configured as a lithium ion capacitor .

Images