JP6889532B2 - Manufacturing method of power storage device and predoping method of power storage device - Google Patents

Description

The present invention relates to a method for manufacturing a power storage device and a method for predoping a power storage device.

Conventionally, as this type of power storage device, a device in which a plurality of through holes are formed in current collectors of a positive electrode and a negative electrode has been proposed (see, for example, Patent Documents 1 to 4). Such a power storage device is, for example, a lithium ion capacitor, and it is said that a large voltage can be obtained by predoping lithium ions on the negative electrode. In this pre-doping, the negative electrode and the Li metal counter electrode are short-circuited, and Li is occluded in the negative electrode from the Li metal counter electrode to the negative electrode through a through hole of the current collector or the like.

Japanese Unexamined Patent Publication No. 2013-258422 Japanese Unexamined Patent Publication No. 2013-206705 Japanese Unexamined Patent Publication No. 2012-174959 JP-A-2009-200302

However, in the above-mentioned power storage devices of Patent Documents 1 to 4, it is necessary to form through holes and cuts necessary for predoping for passing lithium ions in the current collector. In addition, it may take several days to pre-dope, and a new method for manufacturing a power storage device and a pre-doping method have been required.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for manufacturing a power storage device and a method for pre-doping a power storage device, which can further simplify the pre-doping process of electrodes.

As a result of diligent research to achieve the above-mentioned object, the present inventors have conducted a dope solution containing a reduced aromatic hydrocarbon compound and a metal ion in an electrode containing a layered structure of an aromatic dicarboxylic acid metal salt. It has been found that a novel production method and a pre-doping method can be provided, which simplifies the treatment, and the present invention has been completed.

That is, the method of manufacturing the power storage device disclosed in this specification is
A method for manufacturing a power storage device equipped with electrodes.
This includes a step of pre-doping the metal ions to the electrodes by inserting the electrode containing the layered structure of the aromatic dicarboxylic acid metal salt into a dope solution containing the aromatic hydrocarbon compound in the reduced state and the metal ions. ..

Further, the pre-doping method of the power storage device disclosed in the present specification is described.
It is a pre-doping method for a power storage device equipped with electrodes.
The metal ion is pre-doped into the electrode by putting the electrode containing the layered structure of the aromatic dicarboxylic acid metal salt into a dope solution containing the reduced aromatic hydrocarbon compound and the metal ion.

In the method of manufacturing the power storage device and the method of predoping disclosed in the present specification, the predoping process of the electrode can be further simplified. The reason why such an effect is obtained is presumed as follows. For example, according to a dope solution containing a reduced aromatic hydrocarbon compound and a metal ion, the aromatic dicarboxylic acid acts directly on the dope solution simply by bringing the electrode containing the aromatic dicarboxylic acid metal salt into contact with each other. Metal ions can be directly pre-doped into the metal salt. Therefore, for example, the electrodes can be pre-doped without forming through holes or the like in the current collector.

Explanatory drawing which shows an example of the structure of the layered structure included in an electrode. The schematic diagram which shows an example of the effect which pre-doped into the power storage device. The schematic diagram which shows an example of the non-aqueous power storage device 20. The schematic diagram which shows an example of the assembled battery 30. XRD measurement results of the electrodes before and after pre-doping of Examples 1 to 4. XRD measurement results of the electrodes before and after pre-doping of Examples 5 and 6. XRD measurement results of the electrodes before and after the pre-doping of Comparative Examples 1 and 2. Charge / discharge curves of the power storage devices of Examples 1 to 3. The charge / discharge curve of the power storage device of the fourth embodiment. The charge / discharge curve of the power storage device of Examples 5 and 6. Charge / discharge curves of the power storage devices of Comparative Examples 1 and 2.

The method for manufacturing the power storage device disclosed in the present specification includes, for example, an electrode manufacturing step of manufacturing an electrode, a predoping step of predoping metal ions on an electrode (particularly a negative electrode), and a metal ion between the predoped negative electrode and the positive electrode. It may include a cell manufacturing step of inserting an ion conduction medium for conducting the above. It should be noted that the steps other than the pre-doping step may be omitted. This power storage device includes a positive electrode, a negative electrode, and an ion conduction medium. The positive electrode may contain a positive electrode active material. The negative electrode contains a layered structure that occludes and releases metal ions, which are carriers, as a negative electrode active material. The ion conduction medium is interposed between the positive electrode and the negative electrode to conduct metal ions. This power storage device may be, for example, an electric double layer capacitor, a hybrid capacitor, a pseudo electric double layer capacitor, a lithium ion battery, or the like. The metal ion as a carrier may be an alkali metal ion of any one or more of Li, Na, K and the like. Here, for convenience of explanation, a lithium ion capacitor in which the metal ions occluded and released into the layered structure by charging and discharging are Li ions will be mainly described below.

(Electrode manufacturing process)
In this step, a positive electrode and a negative electrode are manufactured. The negative electrode produced in this step may contain a layered structure as a negative electrode active material. FIG. 1 is an explanatory diagram showing an example of the structure of the layered structure of the present invention. This layered structure has an organic skeleton layer in which one or more aromatic ring structures are connected, and an alkali metal element layer in which an alkali metal element is coordinated with oxygen contained in the organic skeleton layer to form a skeleton. It may be a thing. It is structurally stable that this layered structure is formed in layers by the π-electron interaction of aromatic compounds and has a monoclinic crystal structure belonging to _{the space group P2 1 / c.} Yes, preferred. Further, it is structurally stable that the layered structure has a structure of the following formula (1) in which four oxygens of different dicarboxylic acid anions and an alkali metal element form a four coordination. preferable. However, in this formula (1), R has one or more aromatic ring structures, and two or more of the plurality of Rs may be the same, or one or more may be different. Further, A is an alkali metal element. As described above, it is preferable to have a structure in which the organic skeleton layer is bonded by the alkali metal element.

In this layered structure, when the organic skeleton layer has two or more aromatic ring structures, it may be, for example, an aromatic polycyclic compound in which two or more aromatic rings such as biphenyl are bonded, or 2 such as naphthalene, anthracene, and pyrene. A condensed polycyclic compound obtained by condensing the above aromatic rings may be used. This aromatic ring may be a five-membered ring, a six-membered ring, or an eight-membered ring, and a six-membered ring is preferable. The aromatic ring is preferably 2 or more and 5 or less. When the number of aromatic rings is 2 or more, a layered structure is likely to be formed, and when the number of aromatic rings is 5 or less, the energy density can be further increased. The organic skeleton layer may have a structure in which one or more carboxy anions are bonded to the aromatic ring. The organic skeleton layer preferably contains an aromatic compound in which one and the other of the dicarboxylic acid anions are bonded at diagonal positions of the aromatic ring structure. The diagonal position to which the carboxylic acid is bonded may be the position farthest from the bonding position of one carboxylic acid to the bonding position of the other carboxylic acid. For example, if the aromatic ring structure is naphthalene, the positions are 2 and 6. Can be mentioned. This organic skeleton layer may be composed of an aromatic compound containing a structure represented by the general formula (2). Specifically, the organic skeleton layer may include any one or more aromatic compounds of the following formulas (3) to (5). However, in the formulas (3) to (5), it is preferable that a is an integer of 1 or more and 5 or less, and b is an integer of 0 or more and 3 or less. In this range, the size of the organic skeleton layer is suitable, and the charge / discharge capacity can be further increased. In the formulas (3) to (5), these aromatic compounds may have a substituent and a hetero atom in their structure. Specifically, instead of the hydrogen of the aromatic compound, a halogen, a chain or cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a carbonyl group and an acyl group. , An amide group or a hydroxyl group may be used as a substituent, or a structure in which nitrogen, sulfur or oxygen is introduced instead of the carbon of the aromatic compound may be used.

The alkali metal contained in the alkali metal element layer can be, for example, any one or more of Li, Na, K and the like, but Li is preferable. The metal ions contained in the ionic conduction medium and occluded and released into the layered structure by charging and discharging may be different from or the same as the alkali metal elements contained in the alkali metal element layer, for example. , Li, Na, K, and the like, whichever is one or more. Further, since the alkali metal element contained in the alkali metal element layer forms the skeleton of the layered structure, it is presumed that the alkali metal element is not involved in the ion movement accompanying charge / discharge, that is, it is not occluded and released during charge / discharge. .. In the energy storage mechanism, organic framework layer of the layered structure redox (e ^-) while functioning as a site, the alkali metal element layer and functions as a storage site for the metal ion is a carrier (alkali metal ion adsorption site) Conceivable. The layered structure is preferably one or more of, for example, 2,6-naphthalenedicarboxylic acid alkali metal salt, 4,4'-biphenyldicarboxylic acid alkali metal salt and terephthalic acid alkali metal salt.

In this step, for example, a layered structure which is a negative electrode active material, a conductive material, and a binder are mixed, and an appropriate solvent is added to form a paste-like negative electrode mixture, which is applied to the surface of the current collector. It may be dried and, if necessary, compressed to increase the electrode density to form a negative electrode. Conductive materials include, for example, graphite such as natural graphite (scaly graphite, scaly graphite) and artificial graphite, acetylene black, carbon black, Ketjen black, carbon whisker, needle coke, carbon fiber, metal (copper, nickel, aluminum, etc.). One type or a mixture of two or more types such as silver, gold, etc. can be used. Among these, carbon black and acetylene black are preferable as the conductive material from the viewpoint of electron conductivity and coatability. The conductive material is preferably contained in a range of 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the total solid content of the negative electrode mixture. The binder plays a role of binding the active material particles and the conductive material particles, and for example, cellulose-based carboxymethyl cellulose (CMC), styrene-butadiene copolymer (SBR), polyvinyl alcohol, etc., which are water-based binders, etc. It is preferable to use an aqueous dispersion or the like alone or as a mixture of two or more kinds. The binder is, for example, a fluororesin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), or fluororubber, a thermoplastic resin such as polypropylene or polyethylene, or an ethylenepropylene diene monomer (EPDM) rubber. , Sulfated EPDM rubber, natural butyl rubber (NBR) and the like can be used alone or as a mixture of two or more kinds. This negative electrode mixture preferably contains a water-soluble polymer, which is at least one of carboxymethyl cellulose and polyvinyl alcohol, in a range of 1% by mass or more and 10% by mass or less with respect to the total solid content of the negative electrode mixture, and 2% by mass. More preferably, it is contained in the range of% or more and 8% by mass or less. Further, the negative electrode mixture preferably contains a styrene-butadiene copolymer in a range of 8% by mass or less with respect to the total solid content of the negative electrode mixture. Examples of the method for applying the negative electrode mixture include roller coating such as applicator roll, screen coating, doctor blade method, spin coating, bar coater, etc., and any of these can be used to obtain an arbitrary thickness and shape. be able to. As the current collector, aluminum, copper, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, conductive glass and the like can be used. Examples of the shape of the current collector include a foil shape, a film shape, and a sheet shape. As the thickness of the current collector, for example, one having a thickness of 1 to 500 μm is used.

Further, the negative electrode may be fired in a temperature range of 250 ° C. or higher and 450 ° C. or lower in an inert atmosphere after the negative electrode mixture is formed on the current collector. By doing so, the crystal structure can be made more suitable, the π-electron interaction of the aromatic compound is enhanced, the transfer of electrons is facilitated, and the charge / discharge characteristics can be further enhanced.

The positive electrode produced in this step may be a known positive electrode used in a capacitor, a lithium ion capacitor, or the like. The positive electrode may contain, for example, a carbon material as the positive electrode active material. The carbon material is not particularly limited, but for example, activated carbons, cokes, glassy carbons, graphites, graphitizable carbons, pyrolytic carbons, carbon fibers, carbon nanotubes, etc. Examples include graphite. Of these, activated carbons showing a high specific surface area are preferable. Activated carbon as a carbon material preferably has a specific surface area of 1000 m ² / g or more, and more preferably 1500 m ² / g or more. When the specific surface area is 1000 m ² / g or more, the discharge capacity can be further increased. The specific surface area of this activated carbon ^{is preferably 3000 m 2} / g or less, and ^{more preferably 2000 m 2} / g or less, from the viewpoint of ease of production. It is considered that at the positive electrode, at least one of the anion and the cation contained in the ion conduction medium is adsorbed and desorbed to store the electricity, but further, at least one of the anion and the cation contained in the ion conduction medium is inserted and desorbed. It may be used to store electricity.

Alternatively, the positive electrode to be produced may be a positive electrode used in a general lithium ion battery. In this case, as the positive electrode active material, a sulfide containing a transition metal element, an oxide containing lithium and a transition metal element, or the like can be used. Specifically, _{transition metal sulfides such as TiS 2} , TiS ₃ , MoS ₃ , and FeS _2, and the basic composition formula is Li _(1-x) MnO ₂ (0 <x <1, etc., the same applies hereinafter) and Li _{(1). -x)} Lithium manganese composite oxide with Mn ₂ O _{4, etc., Lithium cobalt composite oxide with basic composition formula as Li (1-x)} CoO _2, etc., basic composition formula as Li _(1-x) NiO _2, etc. A lithium nickel composite oxide having a basic composition formula of LiV ₂ O ₃ or the like, a transition metal oxide having a basic composition formula of V ₂ O _{5 or the like can be used.} Of these, lithium transition metal composite oxides, such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , and LiV ₂ O ₃ , are preferred. The "basic composition formula" means that other elements may be contained.

In this step, for example, the above-mentioned positive electrode active material, the conductive material, and the binder are mixed, and an appropriate solvent is added to form a paste-like positive electrode mixture, which is applied to the surface of the current collector, dried, and required. The positive electrode may be formed by compression in order to increase the electrode density. When the positive electrode active material is a carbon material, the positive electrode may not contain a conductive material. As the conductive material, the binder, and the like used for the positive electrode, those exemplified for the negative electrode can be used.

(Pre-doping process)
In this step, metal ions are pre-doped into the negative electrode by adding an electrode (negative electrode) containing a layered structure of an aromatic dicarboxylic acid metal salt to a dope solution containing a reduced aromatic hydrocarbon compound and metal ions. .. FIG. 2 is a schematic view showing an example of the effect of predoping metal ions on the power storage device. FIG. 2 shows the charge / discharge potentials of each electrode of a power storage device (lithium ion capacitor) including a positive electrode using activated carbon as a positive electrode active material and a negative electrode using dilithium aromatic dicarboxylic acid as a negative electrode active material. In the lithium ion capacitor, if the negative electrode is occluded (charged) with lithium in advance by Li predoping, as shown in FIG. 2, the usable capacitance region can be increased as compared with the one without predoping. The dope solution used in this step may contain an aromatic hydrocarbon compound which is one or more of the following formulas (6) and (7). Specifically, the aromatic hydrocarbon compound is preferably one or more of naphthalene, biphenyl, orthoterphenyl, anthracene and paraterphenyl. The aromatic hydrocarbon compound contained in the dope solution may have a structure different from that of the aromatic dicarboxylic acid metal salt contained in the electrode, or may have the same structure, but the same structure. This is preferable from the viewpoint of affinity.

Further, the metal ion contained in this dope solution is preferably one or more of alkali metal ions such as lithium ion, sodium ion and potassium ion. This metal ion is an ion of a carrier for charging / discharging a power storage device. Moreover, this dope solution may contain one or more solvents of tetrahydrofuran (THF), dimethoxyethane, dioxolane and dioxane. This dope solution may be obtained by one or more of the following formulas (8) and (9). That is, the aromatic hydrocarbon compound and the alkali metal in a metallic state may be added to the solvent. More specifically, as shown in the following formulas (10) to (12), naphthalene, diphenyl, terphenyl and Li metal may be reacted in a THF solvent. In this way, a dope solution containing a reduced aromatic hydrocarbon compound and a metal ion can be prepared. Then, in this step, the metal ion M can be pre-doped into the aromatic dicarboxylic acid metal salt as in the following formulas (13) and (14).

The concentration of the reduced aromatic hydrocarbon compound or metal ion in the dope solution is preferably in the range of 0.5 mol / L or more and 3 mol / L or less, for example. In this step, the temperature for pre-doping treatment may be, for example, in the range of 0 ° C. or higher and 80 ° C. or lower, and is preferably near room temperature (20 ° C. to 25 ° C.). The time for immersing the electrode in the dope solution is preferably, for example, 48 hours or less, 24 hours or less, and the like. The immersion time is preferably 1 hour or longer, and may be 4 hours or longer. In this step, the amount of metal ions pre-doped into the electrode can be adjusted by appropriately changing the concentration of the doping solution, the pre-doping temperature, the pre-doping time, etc. according to the size of the electrode, the amount of the active material, and the like. it can. Of these, the pre-dope amount can be adjusted relatively easily by adjusting the time for immersing the electrode in the dope solution. Then, the electrode for which pre-doping has been completed may be pulled out from the doping solution and dried. In this step, simply by acting the electrode containing the layered structure of the aromatic dicarboxylic acid metal salt and the pre-doped solution, a chemical reaction occurs between the doped solution and the layered structure, and metal ions can be easily applied to the electrode. The layered structure can be pre-doped, i.e. selectively charged. In this step, it is possible to easily charge only this electrode without using an electrode in which a mixture is applied to a current collector having a through hole and a metallic lithium electrode, which has been conventionally performed, and then a charge / discharge reaction is performed. Can be made possible. As a result, the pre-doping step can be shortened, the power storage device can be assembled without using a special member such as a current collector having a through hole, and the productivity can be further improved.

(Cell manufacturing process)
In this step, the electrode after predoping is used as a negative electrode, and an ion conduction medium that conducts metal ions is inserted between the negative electrode and the positive electrode. The positive electrode and the negative electrode may be arranged in the cell case. At this time, a separator may be arranged between the positive electrode and the negative electrode. The ionic conduction medium may be, for example, a non-aqueous electrolyte solution containing a supporting salt (supporting electrolyte) and an organic solvent. As the supporting salt, a known supporting salt such as an alkali metal salt can be used. Examples of the alkali metal salt include _{lithium salts such as LiPF 6} , LiClO ₄ , LiAsF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N, and LiN (C ₂ F ₅ SO ₂ ) ₂ , and corresponding to these. Examples include sodium salt and potassium salt. These supporting salts may be used alone or in combination of two or more. The concentration of the supporting salt is preferably 0.1 to 2.0 M, more preferably 0.8 to 1.2 M. As the organic solvent, for example, an aprotic organic solvent can be used. Examples of such an organic solvent include cyclic carbonates, chain carbonates, cyclic esters, cyclic ethers, chain ethers and the like. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate and the like. Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and the like. Examples of the cyclic ester carbonate include gamma-butyrolactone and gamma-valerolactone. Examples of the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran and the like. Examples of the chain ether include dimethoxyethane and ethylene glycol dimethyl ether. These may be used alone or in combination of two or more. In addition, as the non-aqueous electrolyte solution, a nitrile solvent such as acetonitrile or propylnitrile, an ionic liquid, a gel electrolyte, or the like may be used. Alternatively, the ionic conductive medium is bound by a solid ionic conductive polymer, a polymer gel composed of a polymer and a supporting salt, an inorganic solid electrolyte, a mixed material of an organic polymer electrolyte and an inorganic solid electrolyte, and an organic binder. Inorganic solid powder or the like can also be used. The separator may have a composition that can withstand the range of use of the power storage device, and examples thereof include polymer non-woven fabrics such as polypropylene non-woven fabrics and polyphenylene sulfide non-woven fabrics, and microporous films of olefin resins such as polyethylene and polypropylene. These may be used alone or in combination.

The shape of the power storage device is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a square type. Further, it may be applied to a large-sized vehicle used for an electric vehicle or the like. FIG. 3 is a schematic view showing an example of the power storage device 20 of the above-described embodiment. The power storage device 20 has a cup-shaped battery case 21, a positive electrode 22 having a positive electrode active material and provided at the lower part of the battery case 21, and a negative electrode active material with respect to the positive electrode 22 via a separator 24. A negative electrode 23 provided at a facing position, a gasket 25 formed of an insulating material, and a sealing plate 26 disposed in the opening of the battery case 21 and sealing the battery case 21 via the gasket 25 are provided. There is. The power storage device 20 is filled with an ion conductive medium 27 in which an alkali metal salt (lithium salt) is dissolved in a space between the positive electrode 22 and the negative electrode 23. The negative electrode 23 contains a layered structure of an aromatic dicarboxylic acid metal salt.

In the method for manufacturing a power storage device described in detail above, the pre-doping process can be further simplified. The reason why such an effect is obtained is presumed as follows. For example, according to a dope solution containing a reduced aromatic hydrocarbon compound and a metal ion, the aromatic dicarboxylic acid acts directly on the dope solution simply by bringing the electrode containing the aromatic dicarboxylic acid metal salt into contact with each other. Metal ions can be directly pre-doped into the metal salt. Therefore, for example, the electrodes can be pre-doped without forming through holes or the like in the current collector.

It goes without saying that the present invention is not limited to the above-described embodiment, and can be implemented in various aspects as long as it belongs to the technical scope of the present invention.

In the above-described embodiment, the electrode in which the positive electrode mixture containing the positive electrode active material is formed in the current collector of the positive electrode and the negative electrode mixture containing the negative electrode active material is formed in the current collector of the negative electrode has been described as an example. A bipolar electrode may be formed in which a positive electrode mixture containing a positive electrode active material is formed on one surface of a current collector and a negative electrode mixture containing a negative electrode active material is formed on the other surface of the current collector. That is, one surface of the power storage device is a positive electrode mixture containing a positive electrode active material that stores and releases an alkali metal, and a negative electrode mixture that contains the above-mentioned layered structure that stores and releases the alkali metal as a negative electrode active material. A positive electrode mixture is formed in 1 and a negative electrode mixture is formed on the other surface , and the elution potential is higher than the oxidation-reduction potential of the positive electrode active material, and the oxidation-reduction potential of the negative electrode active material is higher than the oxidation-reduction potential of the negative electrode active material. A current collector formed of a current collector metal having a low conversion reaction potential may be provided. By doing so, it is not necessary to use different materials for the current collectors of the positive electrode and the negative electrode, and it is possible to further reduce the complexity in the manufacturing process such as material procurement and separate production of the positive electrode and the negative electrode, and the volume occupied by the current collector. Can be further reduced. Further, by stacking a plurality of these bipolar electrodes via an ion conduction medium, a plurality of power storage devices can be efficiently connected. A specific example of this bipolar electrode will be described below, taking as an example the case where the alkali metal to be occluded and released is Li. In this bipolar electrode, the current collector preferably has an aluminum metal as the current collector metal. The alloying reaction of aluminum and lithium occurs at 0.27 V on a lithium metal basis. The layered structure mainly undergoes a charge / discharge reaction in the range of 0.7 V or more and 0.85 V or less based on the lithium metal standard. Therefore, it is possible to use aluminum metal as an alloying reaction potential is lower collector metal and alkali metal than the redox potential of the negative electrode active material.

FIG. 4 is a schematic view showing an example of the assembled battery 30. As shown in FIG. 4, the assembled battery 30 has a negative electrode current collecting terminal 35 at one end and a positive electrode current collecting terminal 36 at the other end, and has a structure in which a plurality of bipolar electrodes 38 and an ion conduction medium 34 are laminated. have. The bipolar electrode 38 includes a current collector 31, a positive electrode mixture layer 32, and a negative electrode mixture layer 33. The current collector 31 has a positive electrode mixture layer 32 formed on one surface and the other. The negative electrode mixture layer 33 is formed on the surface of the surface. A positive electrode mixture layer 32, an ion conduction medium 34, and a negative electrode mixture layer 33 are arranged in this order between the current collectors 31 and the current collectors 31 of the adjacent bipolar electrodes 38. A cell 37 is formed. In this way, the assembled battery 30 has a structure in which a plurality of single batteries 37 sharing the current collector 31 are stacked. In this way, the plurality of cell cells 37 can be laminated more efficiently by using the bipolar electrode 38.

In this assembled battery, the ionic conduction medium may be a liquid, but it is more preferable that the ionic conduction medium is a solid state or a nearly solid state such as a polymer gel electrolyte or an all-solid-state electrolyte. In this way, the bipolar electrode and the ionic conduction medium can be more easily laminated. Examples of all-solid-state electrolytes include garnet-type oxide Li ₇ La ₃ Zr ₂ O ₁₂ , glass ceramics Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ , and glass ceramics Li _{1 + b} Ti ₂ Si _b P. _3-b O ₁₂ , AlPO ₄ , etc. can be mentioned. Examples of the garnet-type oxide include the general formula Li _{5 + z} La ₃ (Zr _z , A _2-z ) O ₁₂ (where 1.4 ≦ z <2, where A is Sc, Ti, V, Y, Nb. , Hf, Ta, Al, Si, Ga and Ge). This is because the potential window is wide and the lithium conductivity is higher. Further, in the assembled battery, the current collector is preferably aluminum as described above. Further, it is more preferable that the alkali metal occluded and released by charging and discharging is lithium. In the conventional lithium ion capacitor, it is necessary to use a current collector having a through hole in the pre-doping process, and when a bipolar electrode is manufactured, a short circuit occurs through the hole portion of the current collector. Therefore, in principle. It was impossible to design a bipolar cell. In this pre-doping step, a pre-doping process for selectively charging only the negative electrode can be performed without using a current collector having through holes, so that a bipolar cell can be designed in a power storage device.

Further, in the above-described embodiment, the method of manufacturing the power storage device including the step of pre-doping the metal ion has been described, but the method of pre-doping the electrode of the power storage device may also be used. That is, in the pre-doping method of this power storage device, metal ions are transferred to the electrode by inserting an electrode containing a layered structure of an aromatic dicarboxylic acid metal salt into a doping solution containing a reduced aromatic hydrocarbon compound and metal ions. Predope. Also in this pre-doping method, the same effect can be obtained by adopting the embodiment described in the above-described embodiment.

Hereinafter, an example in which a method for manufacturing a power storage device is specifically implemented will be described as an example. In the examples, a negative electrode containing a layered structure of dilithium 2,6-naphthalenedicarboxylic acid, or a negative electrode containing a layered structure of dilithium 4,4'-biphenyldicarboxylic acid, and activated carbon having a high specific surface area were contained. A non-aqueous power storage device using a positive electrode and an electrolytic solution composed of a carbonate-based solvent containing _{LiPF 6 will be described as an example.} It goes without saying that the present invention is not limited to the above-described embodiment, and can be implemented in various aspects as long as it belongs to the technical scope of the present invention.

[Example 1]
(Synthesis of 2,6-naphthalenedicarboxylic acid dilithium)
For the synthesis of dilithium 2,6-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and lithium hydroxide monohydrate (LiOH · H ₂ O) were used as starting materials. Methanol (100 mL) was added to lithium hydroxide monohydrate (0.556 g), and the mixture was stirred. After dissolving lithium hydroxide monohydrate, 2,6-naphthalenedicarboxylic acid (1.0 g) was added and stirred for 1 hour. After stirring, the solvent was removed, and the mixture was dried under vacuum at 150 ° C. for 16 hours to obtain a white powder sample of dilithium 2,6-naphthalenedicarboxylic acid as shown in FIG. 1 (formula (15) below).

(Preparation of 2,6-naphthalenedicarboxylic acid dilithium negative electrode)
The obtained dilithium 2,6-naphthalenedicarboxylate was 73.9% by mass, carbon black (TB5500 manufactured by Tokai Carbon) as a particulate carbon conductive material was 13.0% by mass, and carboxymethyl cellulose (CMC) was a water-soluble polymer (CMC). Daicel FineChem, CMC Daicel 1120) was mixed in 5.2% by mass, and styrene-butadiene copolymer (SBR) (BM-400B manufactured by Nippon Zeon) was mixed in 7.8% by mass, and an appropriate amount of water was added and dispersed as a dispersant. Was used as a slurry-like mixture. This slurry-like mixture is uniformly applied to a copper foil current collector having a thickness of 10 μm so that the amount of the dilithium 2,6-naphthalenedicarboxylic acid active material per unit area is 3 mg / cm ^2, and the coating sheet is heated and dried. Made. Then, the coating sheet was pressure-pressed ^{and punched into an area of 2 cm 2} to prepare a disk-shaped electrode.

(Preparation of pre-doping solution and pre-doping)
Naphthalene is dissolved in tetrahydrofuran (THF) as a solvent so as to be 0.1 mol / L, and then a lithium metal equivalent to 0.1 mol / L is added and stirred, as shown in the above formula (10). A dark green Li predoped solution was prepared by the above reaction. The dilithium 2,6-naphthalenedicarboxylic acid negative electrode was immersed in the obtained Li pre-doped solution overnight, and then the electrode was removed from the solution, washed with THF and dried.

[Examples 2 to 4]
In the Li pre-doped solution, Biphenyl was used instead of naphthalene, and the same as in Example 1 except that the Li pre-doped solution was prepared by the reaction as shown in the above formula (11) was designated as Example 2. Further, Example 3 is the same as in Example 1 except that the Li pre-doped solution is prepared by using orthoterphenyl instead of naphthalene in the Li pre-doped solution by the reaction shown in the above formula (12). And said. Further, in the dilithium negative electrode of 2,6-naphthalenedicarboxylic acid, the same as in Example 1 except that an aluminum foil current collector was used instead of the copper foil current collector was used as Example 4.

[Examples 5 and 6]
Example 5 is the same as in Example 1 except that a 4,4'-dilithium biphenyldicarboxylic acid negative electrode as shown in the following formula (16) is used instead of the dilithium negative electrode of 2,6-naphthalenedicarboxylic acid. And said. Example 6 was the same as in Example 2 except that a 4,4'-biphenyldicarboxylic acid dilithium electrode as shown in the following formula was used instead of the dilithium 2,6-naphthalenedicarboxylic acid negative electrode.

[Comparative Examples 1 and 2]
Instead of the dilithium 2,6-naphthalenedicarboxylate negative electrode, 40% by mass of _{graphitized carbon of d 002 = 0.34 nm or more is mixed with graphite of d 002} = 0.388 nm or less, and polyvinylidene fluoride (PVdF) is mixed with the binder. ) (KF Polyma manufactured by Kureha), the negative electrode active material and the binder were mixed at 95/5% by mass, respectively, and prepared using a paste of the negative electrode mixture dispersed with N-methyl-2-pyrrolidone (NMP). Comparative Example 1 was the same as that of Example 1 except that the electrodes were the same as those of Example 1. Further, instead of the dilithium 2,6-naphthalenedicarboxylate negative electrode, 40% by mass% _{of easily graphitized carbon of d 002 = 0.34 nm or more was mixed with graphite of d 002} = 0.388 nm or less, and this active material was mixed with this active material. Carboxymethyl cellulose (CMC) (CMC Daicel 1120 manufactured by Daicel FineChem), which is a water-soluble polymer, and styrene-butadiene copolymer (SBR) (BM-400B manufactured by Nippon Zeon) are mixed and dispersed in a mass ratio of 95: 2: 3. Comparative Example 2 was the same as that of Example 1 except that the electrode was prepared by using the paste of the negative electrode mixture.

(X-ray diffraction measurement)
X-ray diffraction measurement of the 2,6-naphthalenedicarboxylic acid dilithium electrode subjected to the Li pre-doped treatment was performed. The measurement was performed using an X-ray diffractometer (Ultima IV manufactured by Rigaku) using CuKα ray (wavelength 1.54051 Å) as radiation. A graphite single crystal monochromator was used to monochromate the X-rays, and the measurement was performed by setting the applied voltage to 40 kV and the current to 30 mA. The measurement was performed at a scanning speed of 5 ° / min in an angle range of 2θ = 15 ° to 35 °.

(Preparation of bipolar evaluation cell)
A non-aqueous electrolyte solution was prepared by adding lithium hexafluorophosphate to 1 mol / L to a non-aqueous solvent in which ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate were mixed at a volume ratio of 30:40:30. did. A dilithium 2,6-naphthalenedicarboxylic acid electrode subjected to Li predoping treatment by the above method was used as a working electrode, and a lithium metal foil (thickness 300 μm) was used as a counter electrode, and the non-aqueous electrolytic solution was impregnated between the electrodes. A bipolar evaluation cell was prepared by sandwiching a separator (manufactured by Toray Tonen). The capacity obtained by oxidizing this evaluation cell to 1.5 V at 0.3 mA under a temperature environment of 20 ° C. was defined as the charge capacity. After that, the capacity reduced to 0.5 V at 0.3 mA was defined as the discharge capacity. In Comparative Examples 1 and 2, the capacity reduced to 0.05 V was used as the discharge capacity. Table 1 shows the contents of Examples 1 to 6 and Comparative Examples 1 and 2.

(Results and discussion)
5A and 5B show the XRD measurement results of the electrodes before and after the pre-doping of Examples 1 to 4, FIG. 5 (a) is untreated, FIG. 5 (b) is Example 1, and FIG. 5 (c) is Example 2. FIG. 5 (d) is Example 3, and FIG. 5 (e) is Example 4. 6A and 6B show the XRD measurement results of the electrodes before and after the pre-doping of Examples 5 and 6, FIG. 6 (a) is untreated, FIG. 6 (b) is Example 5, and FIG. 6 (c) is Example 6. is there. 7A and 7B show the XRD measurement results of the electrodes before and after the pre-doping of Comparative Examples 1 and 2. FIG. 7A is untreated, FIG. 7B is Comparative Example 1, and FIG. 7C is Comparative Example 2. is there. 8A and 8B are charge / discharge curves of the power storage devices of Examples 1 to 3, FIG. 8A is Example 1, FIG. 8B is Example 2, and FIG. 8C is Example 3. .. FIG. 9 is a charge / discharge curve of the power storage device of the fourth embodiment. 10A and 10B are charge / discharge curves of the power storage devices of Examples 5 and 6, FIG. 10A is Example 5, and FIG. 10B is Example 6. 11A and 11B are charge / discharge curves of the power storage devices of Comparative Examples 1 and 2. FIG. 11A is Comparative Example 1 and FIG. 11B is Comparative Example 2.

As shown in FIGS. 5 and 6, the crystal structure was changed by performing the pre-doping treatment using the dope solutions of Examples 1 to 6, and the dilithium 2,6-naphthalenedicarboxylic acid in which Li was occluded and Li were occluded. It was found that the crystal structure of the dilithium 4,4′-biphenyldicarboxylic acid was formed. Further, from the comparison between Example 1 and Example 4, the negative electrode current collector was not corroded by the Li pre-doped solution in both the copper foil and the aluminum foil, and the aromatic dicarboxylic acid metal salt was pre-doped with Li. It was found that it forms a crystalline structure. Therefore, it was found that a bipolar electrode can be produced by this pre-doping step. As shown in FIGS. 8 and 9, when charging / discharging was performed using the pre-doped electrodes of Examples 1 to 6, it was possible to confirm the increased charge / discharging capacity due to the charging of Li in the pre-doping treatment. Therefore, it was found that the negative electrode of the aromatic dicarboxylic acid metal salt can be charged in advance by performing this Li pre-doping step. As shown in FIGS. 7 and 11, it was found that the electrode deteriorates when the dope solution is used for the graphite negative electrode. In particular, graphite deteriorated regardless of the type of binder. Further, from the results of Comparative Examples 1 and 2, it was found that the graphite electrode was peeled off by the action of this doping solution. That is, it was presumed that this dope solution showed reactivity with graphite and destroyed the structure. It was speculated that the difference between graphite and the aromatic dicarboxylic acid metal salt is, for example, that the latter contains oxygen inside the skeleton, but graphite does not contain oxygen as a basic structure. In the pre-doped solution used in the examples, it is presumed that oxygen in the solvent exists so as to surround Li. When Li is inserted into the active material, the aromatic dicarboxylic acid metal salt can take in Li via the oxygen moiety existing inside the skeleton, but with materials such as graphite that do not contain oxygen in the skeleton. It was speculated that the structure would be destroyed because Li was inserted in the solvated state. As described above, in an electrode using an aromatic dicarboxylic acid metal salt as an active material, the electrode can be pre-doped by a simple process of immersing the electrode in a dope solution containing a reduced aromatic hydrocarbon compound and a metal ion. I found that I could do it. It was also found that the electrodes can be pre-doped without forming through holes or the like in the current collector.

The present invention is available in the battery industry.

20 non-aqueous secondary battery, 21 battery case, 22 positive electrode, 23 negative electrode, 24 separator, 25 gasket, 26 sealing plate, 27 ion conductive medium, 30 assembled batteries, 31 current collector, 32 positive electrode mixture layer, 33 negative electrode combination Material layer, 34 ion conductive medium, 35 negative electrode current collecting terminal, 36 positive electrode current collecting terminal, 37 cell, 38 bipolar electrode.

Claims (10)

A method for manufacturing a power storage device equipped with electrodes.
The step of pre-doping the metal ion to the electrode by putting the electrode containing the layered structure of the aromatic dicarboxylic acid alkali metal salt into a dope solution containing the aromatic hydrocarbon compound in the reduced state and the metal ion is included. Manufacturing method of power storage device. The method for producing a power storage device according to claim 1, wherein the dope solution contains the aromatic hydrocarbon compound which is one or more of the following formulas (1) and (2).

The method for producing a power storage device according to claim 1 or 2, wherein the dope solution contains the aromatic hydrocarbon compound which is one or more of naphthalene, biphenyl, orthoterphenyl, anthracene and paraterphenyl. The method for manufacturing a power storage device according to any one of claims 1 to 3, wherein the doping solution contains the metal ion which is one or more of lithium ion, sodium ion, and potassium ion. The method for producing a power storage device according to any one of claims 1 to 4, wherein the dope solution contains one or more solvents of tetrahydrofuran, dimethoxyethane, dioxolane and dioxane. The method for manufacturing a power storage device according to any one of claims 1 to 5, wherein the dope solution is obtained by one or more of the following formulas (3) and (4).

The power storage device includes the electrode containing one or more of the layered structure as an active material among 2,6-naphthalenedicarboxylic acid alkali metal salt, 4,4'-biphenyldicarboxylic acid alkali metal salt and terephthalic acid alkali metal salt. The method for manufacturing a power storage device according to any one of claims 1 to 6, which is provided. The method for manufacturing a power storage device according to any one of claims 1 to 7, wherein the electrode contains a conductive material in a range of 1% by mass or more and 20% by mass or less. The method for manufacturing a power storage device according to any one of claims 1 to 8.
A method for manufacturing a power storage device, comprising a step of using the electrode after pre-doping as a negative electrode and inserting an ion conduction medium that conducts the metal ion between the negative electrode and the positive electrode. It is a pre-doping method for a power storage device equipped with electrodes.
A storage device for predoping the metal ions to the electrodes by inserting the electrodes containing a layered structure of an aromatic dicarboxylic acid alkali metal salt into a dope solution containing a reduced aromatic hydrocarbon compound and metal ions. Pre-doping method.

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