JP2013020786A - Electrode and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode and a power storage device capable of realizing a high capacity and a high output.SOLUTION: The electrode comprises a collector 11, and an active material layer including an electrode active material, a conductive particle and a binder 16 and provided on the collector. The electrode active material is a polymer compound having a tetrachalcogenofulvalenes skelton in a repeating unit. In the active material layer, the electrode active material and the conductive particles form aggregates 13 of conductive particles coated with the electrode active material. The aggregate substantially comprises the electrode active material, the conductive particle, and an internal cavity, and the binder exists between the adjacent aggregates.

Description

  In recent years, portable electronic devices such as portable audio devices, cellular phones, and laptop computers have become widespread. In addition, hybrid vehicles using an internal combustion engine and an electric driving force in combination are beginning to spread from the viewpoint of energy saving or the reduction of carbon dioxide emissions. With these popularizations, there is an increasing demand for higher performance of power storage devices used as power sources. Specifically, a power storage device having high output, high capacity, and excellent repetitive characteristics is required.

  Various efforts are being made to improve the performance of electricity storage devices. Since the performance of an electricity storage device largely depends on the positive electrode material and the negative electrode material, positive electrode materials and negative electrode materials are actively studied.

  In order to obtain a battery having a high voltage and a long lifetime, it has been proposed to use a conductive organic complex (Patent Document 1) or a radical compound (Patent Document 2) as an electrode active material. Patent Document 3 proposes to use an organic compound having a π-electron conjugated cloud as an electrode active material in order to improve the repetition characteristics of the electricity storage device. Specifically, for example, it has been proposed to use tetrathiafulvalene (TTF) represented by the following formula (1) as an electrode active material.

  Patent Document 3 also proposes the use of a polymer compound including a plurality of such structures having a π-electron conjugated cloud as an electrode active material for an electricity storage device. Specifically, a polymer compound in which a structure having a π electron conjugated cloud and a polyacetylene chain as a main chain are bonded is disclosed. Patent Document 4 discloses a copolymer compound of a unit having a redox site having a π-electron conjugated cloud in a side chain and a unit not having a redox site in a side chain as an electrode active material of an electricity storage device. ing.

  Various structures have been proposed for the electrode structure of an electricity storage device using an organic compound as an active material. For example, Patent Document 3 discloses a method in which a slurry in which an organic compound having a π-electron conjugated cloud, which includes conductive particles and a binder, is dissolved in a solvent as an electrode active material is applied onto a current collector and dried. A fabricated electrode is disclosed. Such an electrode has a structure in which an active material, conductive particles, and a binder are uniformly dispersed in an active material layer. Patent Document 4 discloses an electrode produced by pressing a mixture obtained by mixing particles of an organic compound having a π electron conjugated cloud, conductive particles, and a binder onto a conductive support and drying the mixture. Is disclosed. Such an electrode has a structure in which the active material is present as particles in the active material layer. Patent Document 5 discloses an electrode including particles in which a region of a radical compound that is an electrode active material and a region of a conductive material are integrated for the purpose of improving repetition characteristics.

JP 60-14762 A JP 2002-117852 A JP 2004-111374 A International Publication No. 2009/157206 JP 2002-298850 A

  As described above, in order to obtain high capacity, high output, and excellent repetitive characteristics, Patent Documents 3 and 4 propose electrode active materials having a π-electron conjugated cloud as a redox site. However, knowledge about the electrode structure of the electricity storage device that can fully utilize the characteristics of these electrode active materials, in particular, the electrode structure that achieves both high capacity and high output has not been sufficient.

  In view of such problems, an object of the present invention is to provide an electrode having high capacity, excellent repetitive characteristics, and high output, and an electric storage device using the electrode.

That is, the present invention
A current collector,
An active material layer including an electrode active material, conductive particles, and a binder, and provided on the current collector;
With
The electrode active material is a polymer compound having a tetrachalcogenofulvalene skeleton in a repeating unit,
In the active material layer, the electrode active material and the conductive particles form an aggregate of the conductive particles coated with the electrode active material,
The aggregate substantially consists of the electrode active material, the conductive particles, and internal voids,
An electrode is provided in which the binder is present between the aggregates adjacent to each other.

From another point of view, the present invention
Preparing an active material slurry comprising conductive particles, a polymer compound having a tetrachalcogenofulvalene skeleton in a repeating unit, and a solvent capable of dissolving the polymer compound;
Removing the solvent from the active material slurry so as to obtain an aggregate of the conductive particles coated with the polymer compound;
Forming an active material layer on a current collector using the aggregate and the binder;
An electrode manufacturing method is provided.

From another viewpoint, the present invention provides:
A positive electrode comprising the electrode of the present invention;
A negative electrode containing a negative electrode active material capable of inserting and extracting lithium ions;
An electrolyte solution containing a salt of the lithium ion and anion and filled between the positive electrode and the negative electrode;
An electricity storage device is provided.

  The electrode of the present invention includes a polymer compound having a tetrachalcogenofulvalene skeleton as a repeating unit. Therefore, the redox reaction can be performed stably and repeatedly, and excellent repeatability can be obtained. In the active material layer, the polymer compound that is an electrode active material covers at least a part of the surface of the conductive particles to form an aggregate. Therefore, the contact area between the polymer compound and the conductive particles is large, and electrons move smoothly between the polymer compound and the conductive particles. Since the polymer compound is present as a film on the surface of the conductive particles, the moving distance required for the counter ion in the electrolytic solution to reach the redox site in the polymer compound is shortened. Since the aggregate has voids inside, the electrolytic solution enters the voids, and the contact area between the electrolytic solution and the polymer compound increases. For this reason, an anion becomes easy to reach | attain the oxidation-reduction site | part in a polymer compound. By these, the resistance at the time of oxidation reduction can be reduced. That is, a high output electrode can be realized.

  A binder is present between the aggregates composed of the polymer compound and the conductive particles. In the active material layer, the aggregates are fixed by a binder. Therefore, it is possible to easily increase the thickness of the active material layer. That is, since the occupied volume of the electrode active material layer in the electricity storage device can be increased and the occupied volume of a member such as a current collector can be reduced, the capacity of the electricity storage device can be increased.

  When a conventional production method is employed, an active material layer is formed by molding a mixture obtained by mixing a polymer compound, conductive particles, a binder and the like at once. For this reason, the contact between the polymer compound and the conductive particles is prevented by the binder, and the resistance during oxidation and reduction is increased. On the other hand, according to the production method of the present invention, an aggregate composed of a polymer compound and conductive particles was prepared in advance, and then the aggregate and other constituent materials were mixed and obtained. An active material layer is formed by molding the mixture. As a result, an electrode structure in which the contact area between the polymer compound and the conductive particles is large and the polymer compound exists as a coating on the surface of the conductive particles can be obtained, and a high output electrode can be realized. it can. As described above, since the aggregate can be handled in the same manner as a conventional positive electrode active material such as lithium oxide at the time of producing the electrode, the production of the electrode is easy.

  Therefore, by using the electrode of the present invention and the manufacturing method thereof, an electricity storage device having excellent repetitive characteristics, high capacity, and high output can be realized.

It is typical sectional drawing which shows the structure of the electrode by this invention. It is typical sectional drawing which expands and shows a part of active material layer of the electrode by this invention. It is typical sectional drawing which shows the coin-type electrical storage device which is one Embodiment of the electrical storage device by this invention. (A) is the SEM image which shows the cross section of the aggregate of Example 1, (b) and (c) are the carbon distribution image and sulfur distribution image in the cross section.

  Hereinafter, taking the lithium secondary battery as an example, the electrode of the present invention and the electricity storage device using the same will be described. However, the present invention is not limited to a lithium secondary battery or an electrode for a lithium secondary battery, but is also suitably used for an electrochemical element such as a capacitor using a chemical reaction.

  FIG. 1 schematically shows a cross-sectional structure of an electrode 10 according to an embodiment of the present invention. The electrode 10 includes a current collector (conductive support) 11 and an electrode active material layer 12 provided on the current collector 11. The electrode active material layer 12 includes an aggregate 13 substantially composed of an electrode active material and conductive particles. The aggregate 13 is fixed in the electrode active material layer 12 together with the binder 16. The binder 16 exists between the adjacent aggregates 13. The electrode active material layer 12 has a porous structure so that the electrolyte solution can be retained when a battery including the electrode 10 is configured.

  One of the features of the present invention is that in the electrode active material layer 12, the polymer compound that is the electrode active material covers a part of the surface of the conductive particles and aggregates to form an aggregate (heavy layer). It is the point which exists as the coalescence covering particle | grain 13). The aggregate 13 has a structure described below.

  FIG. 2 is an enlarged view schematically showing the aggregate 13 included in the active material layer 12. The aggregate 13 includes a polymer compound 14 that is an electrode active material and conductive particles 15, and the polymer compound 14 covers at least a part of the surface of the conductive particles 15. That is, the polymer compound 14 exists in a state of a film covering the conductive particles 15. Further, the aggregate 13 has a gap 13a inside. In the present specification, the polymer compound 14 covering the conductive particles 15 means that the polymer compound 14 exists as a continuous body along the surface of the conductive particles 15. Although it is preferable that the polymer compound 14 forms a continuous film having a uniform film thickness on the surface of the conductive particles 15, the film thickness of the continuous film may not be constant.

  In FIG. 2, the cross section of each conductive particle 15 is shown as an ellipse, but the shape of the conductive particle 15 is not particularly limited. The shape of the conductive particles 15 may be one of various shapes of conductive aids generally used as a conductive aid for electrode materials, such as a spherical shape, an ellipsoid shape, a scale shape, and a fiber shape. In FIG. 2, the polymer compound 14 completely covers the secondary particles constituted by the collection of the conductive particles 15, but the polymer compound 14 needs to completely cover the secondary particles. Instead, it is sufficient that at least a part of the surface of the secondary particles is covered.

  Since the aggregate 13 has such a structure, the contact area between the conductive particles 15 and the polymer compound 14 as the electrode active material increases, and oxidation occurs between the polymer compound 14 and the conductive particles 15. Electrons move smoothly during the reduction reaction. Furthermore, the redox reaction of the polymer compound 14 is likely to occur uniformly. It is preferable that the aggregate 13 does not contain a binder.

  The polymer compound 14 is a polymer compound having a tetrachalcogenofulvalene skeleton as a repeating unit. A portion having a tetrachalcogenofulvalene skeleton in the polymer compound 14 has a π-conjugated potential cloud and functions as a redox site. The tetrachalcogenofulvalene skeleton is stable even in a two-electron oxidized state. Therefore, the polymer compound 14 having the skeleton as a repeating unit can stably perform a redox reaction repeatedly. A molecule including a tetrachalcogenofulvalene skeleton has a lower solubility in an organic solvent as the molecular weight is increased. Since the polymer compound 14 having a high molecular weight is used as the electrode active material, the dissolution of the electrode active material in the electrolytic solution containing the organic solvent is suppressed, and the deterioration of the repeated characteristics is suppressed. As described above, the polymer compound 14 is suitable as a power storage material, and excellent repeatability can be obtained by using the polymer compound 14 as an electrode active material.

  When the polymer compound 14 undergoes a redox reaction, the anion in the electrolytic solution needs to move from the surface of the polymer compound 14 in contact with the electrolytic solution to the vicinity of the redox site in the polymer compound 14. In the polymer compound 14, anions are less likely to move than in the electrolytic solution, and this tends to be a resistance component during charging and discharging. The shorter the moving distance of the anion from the surface of the polymer compound 14 in contact with the electrolytic solution to the redox site in the polymer compound 14, the faster the redox reaction proceeds.

  According to this embodiment, since the polymer compound 14 exists in a thin film state in the active material layer 12, the anion moves from the surface of the polymer compound 14 in contact with the electrolytic solution to the redox site in the polymer compound 14. The distance is short. Furthermore, since the space | gap 13a exists in the aggregate 13, when the electrolyte solution permeates into this space | gap 13a, the contact area of the polymer compound 14 and electrolyte solution expands. For this reason, the anion easily reaches the vicinity of the portion having the tetrachalcogenofulvalene skeleton, which is a redox site present in the polymer compound 14, and the resistance component in the electrode 10 can be reduced.

  Usually, in order to realize a structure in which an organic compound is used as the electrode active material and the organic compound covers the conductive particles in the electrode, the following method is employed. That is, a paste is prepared by dispersing or dissolving an organic compound as an electrode active material in a solvent and mixing it with conductive particles. An electrode can be produced by applying a paste on a current collector to form a coating film and then drying the coating film. However, when an electrode is manufactured by such a method, it is difficult to increase the thickness of the active material layer. When using a paste with high viscosity, it is possible to form a thick coating film, but it is difficult to obtain a paste and coating film with a uniform composition, so an active material layer with a uniform composition is obtained. Is difficult. When a paste having a low viscosity is used, a thick coating film can be formed by overcoating or the like. However, when the paste is applied on the lower layer fixed by the previous coating and drying, the paste penetrates into the lower layer, or the solvent in the paste dissolves or desorbs the electrode active material in the lower layer. For this reason, it is difficult to obtain an active material layer having a uniform composition and structure.

  On the other hand, in the present embodiment, the aggregate 13 has already realized a structure in which the polymer compound 14 that is an electrode active material covers the conductive particles 15. Aggregates 13 exist as individual particles, and active material layer 12 is formed by bonding aggregates 13 together using binder 16. By using the binder 16 and the aggregate 13 prepared in advance, the manufacturing method is not limited, and the active material layer 12 is easily formed, the structure of the electrode 10 is realized, and the above-described effects are obtained. be able to. For example, the electrode 10 can be produced by kneading a mixture containing the aggregate 13 and the binder 16 and rolling the mixture onto the current collector 11. By using such a method, the active material layer 12 can be thickened while the active material layer 12 has a uniform composition and structure.

  The shape of the binder 16 is indicated by a line in FIG. 1, but the shape of the binder 16 in the active material layer 12 is not particularly limited. The binder 16 may form a line or network structure to bond the aggregates 13 together, or may bind the aggregates 13 in the form of small dots that contact the aggregate 13.

  The aggregate 13 can be obtained, for example, by the following manufacturing method. First, an active material slurry is prepared by dissolving the polymer compound 14 in a solvent and dispersing the conductive particles 15. Next, the solvent is removed from the active material slurry so that an aggregate 13 of the conductive particles 15 coated with the polymer compound 14 is obtained. For example, the obtained active material slurry is applied on a support to form a coating film. By drying this coating film, a sheet-like composite is produced. By peeling and pulverizing the obtained sheet-like composite, particles in which the conductive particles 15 are coated with the polymer compound 14, that is, the aggregates 13 are obtained. In another method, the solvent is removed from the active material slurry by spray drying the active material slurry obtained in the same manner as described above. Aggregates 13 are also obtained by this method. In order to control the particle size of the aggregate 13, a method of obtaining the aggregate 13 by spray drying the active material slurry is preferable.

  As a solvent for preparing the active material slurry, N-methylpyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), tetrahydrofuran (THF), toluene, dimethylformamide (DMF), dimethylacetamide Examples include (DMAc), dimethyl sulfoxide (DMSO), and a solvent that can dissolve the polymer compound 14 such as chloroform. From the viewpoint that it can be easily removed in a later step, NMP, DMI and THF are preferable as the solvent for preparing the active material slurry. The conductive particles 15 are not dissolved in the solvent.

  The weight ratio of the polymer compound 14 in the aggregate 13 is preferably 1 to 90%. When the weight ratio of the polymer compound 14 is 1% or less, since the ratio of the electrode active material in the active material layer 12 is low, the high-capacity electrode 10 may not be realized. When the weight ratio of the polymer compound 14 is 90% or more, the film thickness of the polymer compound 14 covering the conductive particles 15 increases. For this reason, it becomes difficult to ensure sufficient electron conductivity in the electrode active material 14 covering the conductive particles 15, and it becomes difficult to uniformly charge and discharge the entire active material layer 12. From such a viewpoint, the weight ratio of the polymer compound 14 in the aggregate 13 is preferably 1 to 90%, and more preferably 10 to 50%.

  Next, the polymer compound 14 which is an electrode active material will be described. As described above, the polymer compound 14 is a polymer having a tetrachalcogenofulvalene skeleton as a repeating unit. The tetrachalcogenofulvalene skeleton may be contained in the main chain of the repeating unit or may be contained in the side chain. The structure of the portion having a tetrachalcogenofulvalene skeleton is represented, for example, by the following formula (2).

In the formula (2), X ¹ , X ² , X ³ , and X ⁴ are each independently a sulfur atom, an oxygen atom, a selenium atom, or a tellurium atom. One or two selected from Ra, Rb, Rc, and Rd is a bond for bonding to the other part of the main chain or side chain of the polymer. The remaining three or two selected from Ra, Rb, Rc and Rd are each independently a chain aliphatic group, cyclic aliphatic group, hydrogen atom, hydroxyl group, cyano group, amino group , A nitro group, a nitroso group, or an alkylthio group. Each of the chain-like aliphatic group and the cyclic aliphatic group may contain at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, and a boron atom. Ra and Rb may be bonded to each other to form a ring, and Rc and Rd may be bonded to each other to form a ring.

[When the main chain of the repeating unit contains a tetrachalcogenofulvalene skeleton]
First, the polymer compound 14 containing a tetrachalcogenofulvalene skeleton in the main chain of the repeating unit will be described. The polymer compound 14 including the tetrachalcogenofulvalene skeleton in the main chain of the repeating unit has a tetrachalcogenofulvalene skeleton as long as the tetrachalcogenofulvalene skeleton represented by the formula (2) is included in the main chain. It may be a copolymer of a monomer and a monomer having another chemical structure.

  In order to obtain a high energy density, it is preferable that the main chain of the polymer compound 14 is formed by directly bonding the tetrachalcogenofulvalene skeletons to each other. In this case, the polymer compound 14 is, for example, a polymer obtained by copolymerizing two or more monomers each having a tetrachalcogenofulvalene skeleton and having different substituents. Examples of such a copolymer include a copolymer in which two types of repeating units represented by the following formulas (3) and (4) are bonded to each other at the symbol *.

  In formulas (3) and (4), X is independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R5 to R8 are each independently a chain saturated hydrocarbon group, a chain. An unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, and a nitroso group. Yes, the combination of R5 and R6 is different from the combination of R7 and R8. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group.

  The copolymer is composed of two types of repeating units with different substituents bonded to the tetrachalcogenofulvalene skeleton, and the main chain is directly bonded to positions 1 and 4 of the tetrachalcogenofulvalene skeleton. It is formed by. Therefore, since the ratio of the oxidation-reduction site | part occupied in 1 molecule is high, such a polymer compound 14 can accumulate | store an electric charge with a high energy density as an electrical storage material.

  The copolymer composed of the repeating units represented by the formulas (3) and (4) may be any of a block copolymer, an alternating copolymer, and a random copolymer. The block copolymer has a structure in which units in which a plurality of repeating units represented by the formula (3) are directly bonded and units in which a plurality of repeating units represented by the formula (4) are directly bonded are alternately arranged. The alternating copolymer has a structure in which repeating units represented by the formula (3) and repeating units represented by the formula (4) are alternately arranged. The random copolymer has a structure in which the repeating unit represented by the formula (3) and the repeating unit represented by the formula (4) are randomly arranged.

  The copolymer composed of repeating units represented by formulas (3) and (4) is, for example, that R5 and R6 in formula (3) are phenyl groups, and R7 and R8 in formula (4) are chain hydrocarbons. It is a copolymer that is a group. Specifically, the polymer compound 14 has the following formula (3), wherein X in the formulas (3) and (4) is a sulfur atom, R5 and R6 are phenyl groups, and R7 and R8 are decyl groups. It may be a copolymer represented by 5).

  In formula (5), the sum of n and m represents the degree of polymerization and is an integer of 2 or more. The repeating units having two tetrachalcogenofulvalene skeletons may be regularly arranged or randomly arranged. The ratio between n and m is arbitrary. The molecular weight of the polymer is preferably large so that the polymer does not dissolve in the electrolyte. Specifically, it is preferable that four or more tetrachalcogenofulvalene skeletons are included. That is, when the polymer compound 14 is a copolymer represented by the formula (5), the degree of polymerization (the sum of n and m) is preferably 4 or more.

  The polymer compound 14 containing a tetrachalcogenofulvalene skeleton in the main chain may be a polymer represented by the following formula (6).

  In the formula (6), four X's are each independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R5 and R6 are each independently a chain saturated hydrocarbon group, It is at least one selected from the group consisting of a saturated hydrocarbon group, a cyclic saturated hydrocarbon group, a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, and a nitroso group. The chain saturated hydrocarbon group, the chain unsaturated hydrocarbon group, the cyclic saturated hydrocarbon group, and the cyclic unsaturated hydrocarbon group are each at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. Including species. R9 is a chain unsaturated hydrocarbon group or a cyclic unsaturated hydrocarbon group containing an acetylene skeleton or a thiophene skeleton, and is at least one selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. Including species.

  In the main chain of the polymer represented by the formula (6), the linker represented by R9 and the tetrachalcogenofulvalene skeleton are alternately arranged. As described above, R9 is a chain unsaturated hydrocarbon group or a cyclic unsaturated hydrocarbon group containing an acetylene skeleton or a thiophene skeleton. By arranging R9 in this way, the electronic interaction between the tetrachalcogenofulvalene skeletons is suppressed, and the stability of the electrochemical redox reaction in each tetrachalcogenofulvalene skeleton is enhanced. Can do. As a result, all tetrachalcogenofulvalene skeletons in the polymer compound 14 can perform a reversible oxidation-reduction reaction, and a high capacity electrode active material can be realized.

  For example, in the polymer compound 14 including a tetrachalcogenofulvalene skeleton in the main chain, in the formula (6), X is a sulfur atom, R5 and R6 are phenyl groups, and R9 is represented by the following formula (7). It is a polymer shown in the following formula (8) having a structure. The symbol * in formula (7) represents the end point of the bond.

  The polymer compound 14 containing a tetrachalcogenofulvalene skeleton in the main chain is a polymer having a structure in which R9 in the formula (6) is represented by any one of the following formulas (9-a) to (9-c). Also good. The symbol * in the formulas (9-a) to (9-c) represents a bonding end point.

  The polymer compound 14 having a structure in which R9 in the formula (6) is represented by the formula (9-a) is, for example, a polymer represented by the following formula (10).

  In the formula (10), four Xs are each independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R5, R6 and R10 to R13 are each independently a chain saturated hydrocarbon group. , At least one selected from the group consisting of a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, and a nitroso group Including species. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group.

  The polymer compound 14 having a structure in which R9 in the formula (6) is represented by the formula (9-b) is, for example, a polymer represented by the following formula (11).

  In the formula (11), four Xs are each independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R5, R6, R10 to R12 and R14 are each independently a chain saturated carbonization. Selected from the group consisting of hydrogen group, chain unsaturated hydrocarbon group, cyclic saturated hydrocarbon group, cyclic unsaturated hydrocarbon group, phenyl group, hydrogen atom, hydroxyl group, cyano group, amino group, nitro group and nitroso group Contains at least one. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group.

  In the polymer represented by the formula (10), for example, in the formula (10), X is a sulfur atom, R5 and R6 are a thiohexyl group, a methyl group, or a decyl group, and R10 to R13 are hydrogen atoms. A polymer represented by the following formula (12), (13) or (14).

  In the polymer represented by the formula (10), in the formula (10), X is a sulfur atom, R5 and R6 are phenyl groups, R10 and R13 are methoxy groups, and R11 and R12 are hydrogen atoms. There may be a polymer represented by the following formula (15).

  In the polymer represented by the formula (11), in the formula (11), X is a sulfur atom, R5 and R6 are a methyl group or a phenyl group, and R10 to R12 and R14 are hydrogen atoms, A polymer represented by the formula (16) or (17) may be used.

  Alternatively, R9 in formula (6) may have any structure shown in the following formulas (18) to (22) including a thiophene skeleton. The symbol * in the formulas (18) to (22) represents the end point of the bond.

  Specifically, the polymer represented by the formula (6) has any structure in which X is a sulfur atom and R9 is represented by the formulas (18) to (22) in the formula (6). The polymers shown in the following formulas (23) to (30) may also be used.

  The polymer compound 14 preferably contains four or more tetrachalcogenofulvalene skeletons so that the polymer compound 14 does not dissolve in the electrolytic solution. That is, it is preferable that both n in the formulas (23) to (30) and m in the formula (30) are 4 or more. In the polymer represented by the formula (30), the repeating unit having a tetrathiafulvalene skeleton and the repeating unit having a thiophene skeleton may be regularly arranged or randomly arranged. The ratio between n and m is arbitrary.

  The main chain of the polymer described so far is composed of R1 and R3 in the formula (1), that is, a tetrachalcogenofulvalene skeleton having bonds at the 1st and 4th positions of the tetrachalcogenofulvalene skeleton. It was. However, the tetrachalcogenofulvalene skeleton is a bond between R1 and R2 (or R3 and R4) in formula (1), that is, the 1st and 2nd positions (or 3rd and 4th positions) of the tetrachalcogenofulvalene skeleton. As above, it may constitute the main chain of the polymer. The polymer compound 14 containing a tetrachalcogenofulvalene skeleton in the main chain may be a polymer represented by the following formula (31).

  In the formula (31), four Xs are each independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R15 and R16 are each independently a chain saturated hydrocarbon group, It is at least one selected from the group consisting of a saturated hydrocarbon group, a cyclic saturated hydrocarbon group, a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, and a nitroso group. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group. R27 is a chain unsaturated hydrocarbon group or a cyclic unsaturated hydrocarbon group containing an acetylene skeleton and / or a thiophene skeleton, and is selected from the group consisting of carbon atoms, oxygen atoms, nitrogen atoms, sulfur atoms and silicon atoms. Contains at least one.

  Specifically, R27 in the formula (31) may have a structure represented by any of the following formulas (7) and (9-a) to (9-c). The symbol * in the formulas (7) and (9-a) to (9-c) represents an end point of the bond.

  In the formulas (9-a), (9-b) and (9-c), R10 to R14 each independently represent a chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, or a cyclic saturated hydrocarbon group. , At least one selected from the group consisting of a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group and a nitroso group. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group.

  The polymer represented by the formula (31) may be a polymer represented by the formula (32) having a structure in which R27 in the formula (31) is represented by the formula (9-a).

  In formula (32), four Xs are each independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R15 to R20 each independently represent a chain saturated hydrocarbon group, It includes at least one selected from the group consisting of a saturated hydrocarbon group, a cyclic saturated hydrocarbon group, a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, and a nitroso group. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group.

  The polymer represented by the formula (32) is represented by the following formula (33), in which X is a sulfur atom, R15 and R16 are thiohexyl groups, and R17 to R20 are hydrogen atoms in the formula (32). It may be a polymer.

  The polymer represented by the formula (31) may be a polymer represented by the following formula (34) having a structure in which R27 in the formula (31) is represented by the formula (9-b).

  In the formula (34), four Xs are each independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R15 to R19 and R21 each independently represent a chain saturated hydrocarbon group, a chain At least one selected from the group consisting of a cyclic unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group and a nitroso group Including. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group.

  The polymer compound 14 containing a tetrachalcogenofulvalene skeleton in the main chain may be a polymer represented by the following formula (35).

  In the formula (35), four Xs are each independently an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, and R15, R16, R23 and R24 are each independently a chain saturated hydrocarbon group. , At least one selected from the group consisting of a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, a cyclic unsaturated hydrocarbon group, a phenyl group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, and a nitroso group It is a seed. A chain saturated hydrocarbon group, a chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, and a cyclic unsaturated hydrocarbon group are each independently composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. It contains at least one selected from the group. R22 and R25 each independently represents a chain unsaturated hydrocarbon group or a cyclic unsaturated hydrocarbon group containing an acetylene skeleton and / or a thiophene skeleton, and includes a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, and silicon. It contains at least one selected from the group consisting of atoms.

  In the formula (35), R22 and R25 may have a structure represented by the following formula (7). In this case, the polymer represented by the formula (35) is, for example, the following formula in which, in the formula (35), X is a sulfur atom, R15 and R16 are thiohexyl groups, and R23 and R24 are phenyl groups. It is a polymer shown in (36).

  As described above, the polymer compound 14 including the tetrachalcogenofulvalene skeleton in the main chain preferably includes four or more tetrachalcogenofulvalene skeletons so as not to dissolve in the electrolytic solution. That is, n in Formula (36) is preferably 2 or more.

  Similar to the polymer represented by the formula (6), the polymer represented by the formulas (31) and (35) also includes a chain unsaturated hydrocarbon group or a cyclic unsaturated hydrocarbon containing an acetylene skeleton or a thiophene skeleton. A hydrogen group and a tetrachalcogenofulvalene skeleton are alternately bonded to form a main chain. For this reason, chain unsaturated hydrocarbon groups or cyclic unsaturated hydrocarbon groups suppress electronic interaction between tetrachalcogenofulvalene skeletons, and electrochemical redox reactions in each tetrachalcogenofulvalene skeleton Can improve the stability. As a result, all tetrachalcogenofulvalene skeletons in the polymer can perform a reversible oxidation-reduction reaction, and a high-capacity electrode active material can be realized.

  Each polymer compound 14 described above can be synthesized by polymerizing a monomer containing a tetrachalcogenofulvalene skeleton. As long as it has the structure described above, the polymer compound 14 may be synthesized by any method. However, in order to prevent dislocation of active bonds during polymerization and to form a highly regular polymer compound 14, it is preferable to synthesize the polymer compound 14 by polymerization by a coupling reaction. Specifically, a monomer having a repeating unit structure as described above and having a halogen group or other functional group at a position serving as a bond is polymerized by Sonogashira coupling reaction or other coupling reaction. The polymer compound 14 is preferably synthesized.

[When the side chain of the repeating unit contains a tetrachalcogenofulvalene skeleton]
Next, the polymer compound 14 containing a tetrachalcogenofulvalene skeleton in the side chain of the repeating unit will be described. The polymer compound 14 having a tetrachalcogenofulvalene skeleton in the side chain of the repeating unit has a first unit having the tetrachalcogenofulvalene skeleton in the side chain as a redox site, and a redox reaction site in the side chain. It is a copolymer with no second unit. Specifically, the first unit has a structure represented by the formula (2) in the side chain. Specifically, the second unit does not have, in the side chain, a site where the structure represented by the formula (2) electrochemically performs a redox reaction within a potential range where the redox reaction is performed.

  When the tetrachalcogenofulvalene skeleton is included in the side chain, the tetrachalcogenofulvalene skeletons located in the side chain are likely to be close to each other. When the tetrachalcogenofulvalene skeletons are close to each other, it becomes difficult to secure a movement path of the counter anion to the tetrachalcogenofulvalene skeleton during the oxidation-reduction reaction, and the oxidation-reduction reaction is performed smoothly. It becomes difficult. In addition, since it is difficult to obtain a stable oxidation state of the tetrachalcogenofulvalene skeleton, the oxidation reaction hardly proceeds. This is a resistance to the reaction of the active material. Therefore, the second unit having no redox site in the side chain is copolymerized with the first unit having a tetrachalcogenofulvalene skeleton in the side chain. This reduces steric hindrance in the vicinity of the tetrachalcogenofulvalene skeleton, which is a redox site, and when the redox site is oxidized, the counter anion tends to approach and coordinate with the redox site, thereby preventing the active material reaction. Resistance is reduced.

  A polymer containing a tetrachalcogenofulvalene skeleton in the main chain has a relatively high solubility in solvents such as NMP, DMI, and THF, which are solvents for preparing an active material slurry. This is because the tetrachalcogenofulvalene skeletons closest to each other in the molecule are difficult to overlap. On the other hand, in the case of a polymer containing a tetrachalcogenofulvalene skeleton in the side chain, particularly when the second unit is not included, the tetrachalcogenofulvalene skeletons located in adjacent side chains are easily stacked. Therefore, the solubility of these polymers containing a tetrachalcogenofulvalene skeleton in the side chain tends to be low. When a polymer having low solubility in these solvents is used, it becomes difficult to prepare an active material slurry in which the polymer is dissolved, and it becomes difficult to produce the aggregate 13. Therefore, the second unit having no tetrachalcogenofulvalene skeleton in the side chain is copolymerized with the first unit having the tetrachalcogenofulvalene skeleton in the side chain. Thereby, tetrachalcogenofulvalene skeletons can be prevented from stacking and the solubility of the polymer in the solvent for preparing the active material slurry can be improved.

  In the polymer compound 14 which is a copolymer of the first unit and the second unit, the side chain of the second unit has an affinity for an aprotic polar solvent which is a nonaqueous solvent used in an electrolyte solution described later. It is preferable that the functional group which has property is included. This makes it easier for the solvated counter anion to approach the vicinity of the redox site. Functional groups having such chemical properties include oxygen-containing functional groups such as ester groups, ether groups and carbonyl groups; nitrogen-containing functional groups such as cyano groups, nitro groups and nitroxyl groups; functional groups consisting of carbon and hydrogen. An alkyl group and a phenyl group, and a sulfur-containing functional group such as an alkylthio group, a sulfone group, and a sulfoxide group. The side chain of the second unit preferably contains at least one selected from these functional groups, and may contain two or more. Among these functional groups, the side chain of the second unit preferably contains at least one selected from the group consisting of an ester group, an ether group, and a carbonyl group, which has a high affinity with an aprotic polar solvent.

The terminal portion of the ester group, ether group, carbonyl group, sulfone group and sulfoxide group is not particularly limited, but is preferably an alkyl group having a small number of carbon atoms such as a methyl group or an ethyl group, or an aromatic group. Preferred ester groups include alkyl esters represented by (—COO—CH ₃ ) and (—COO—C ₂ H ₅ ), phenyl esters (—COO—C ₆ H ₅ ), and the like. Preferable ether groups include alkyl ethers represented by (—O—CH ₃ ) and (—O—C ₂ H ₅ ), phenyl ether (—O—C ₆ H ₅ ), and the like. Preferred examples of the carbonyl group include (—C (═O) —CH ₃ ), (—C (═O) —C ₂ H ₅ ), (—C (═O) —C ₆ H ₅ ), and the like. Preferred sulfone groups include (—S (═O) ₂ —CH ₃ ), (—S (═O) ₂ —C ₂ H ₅ ), (—S (═O) ₂ —C ₆ H ₅ ), and the like. Can be mentioned. Preferred sulfoxide groups include (—S (═O) —CH ₃ ), (—S (═O) —C ₂ H ₅ ), (—S (═O) —C ₆ H ₅ ), and the like.

  The main chain of the polymer compound 14 that is a copolymer of the first unit and the second unit is not particularly limited, and includes at least one selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom, and a sulfur atom. Trivalent residues are included as repeating units. The repeating unit may contain a saturated aliphatic group or an unsaturated aliphatic group having 1 to 10 carbon atoms as a substituent. Specifically, as the main chain of the polymer compound 14, polyethylene or polypropylene which is a saturated hydrocarbon; polyacetylene which is an unsaturated hydrocarbon; polycarbonate or polystyrene containing an aromatic; some of these protons are substituted by halogen And so on.

  The degree of polymerization of the polymer compound 14 which is a copolymer composed of the first unit and the second unit is preferably large so that the polymer compound 14 does not dissolve in the electrolytic solution. Specifically, it is preferable that the total number of first units and second units contained in the copolymer is 4 or more, that is, the degree of polymerization is 4 or more. As a result, a power storage material that does not easily dissolve in the electrolyte is realized. More preferably, the polymerization degree of the polymer compound 14 is 10 or more, and more preferably 20 or more and 4000 or less.

  When the side chain of the second unit is a functional group having an affinity for an aprotic polar solvent, the type of side chain of the second unit and the number of units of the second unit relative to the number of units n of the first unit The affinity of the entire copolymer for the aprotic polar solvent can be controlled by the composition ratio m / n of m. Here, m and n are integers of 1 or more. In the present specification, the constituent ratio m / n of the copolymer means an average value of values obtained by dividing the total number m of the second units constituting the copolymer by the total number n of the first units. When the side chain of the second unit is a functional group having an affinity for an aprotic polar solvent, the affinity of the copolymer for a specific aprotic polar solvent is greatly improved, and the degree of polymerization is 10 or more. Even so, the copolymer may be dissolved in the solvent.

  If the copolymer contains any second unit that does not have a redox site in the side chain, the effect of reducing steric hindrance near the redox site can be obtained. Therefore, the component ratio m / n only needs to be larger than zero. In order to increase the affinity of the copolymer for the aprotic polar solvent, it is preferable that the second unit is large. The effect mentioned above can be acquired, so that the composition ratio m / n is large. However, since the second unit does not include an oxidation-reduction site, the charge density of the copolymer tends to decrease when the second unit is too much. When the composition ratio m / n is 5 or less, the charge density can be increased, and a redox reaction can be stably and repeatedly generated. Therefore, the constituent ratio m / n of the first unit and the second unit in the copolymer is preferably greater than 0 and 5 or less.

  The polymer compound 14 which is a copolymer of the first unit and the second unit is represented by a structure represented by the following formula (37) in which two repeating units are bonded to each other with a symbol *.

  In formula (37), R31 and R32 constitute the main chain of the copolymer. R31 and R32 are trivalent residues, each independently at least one selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom and a sulfur atom, a saturated aliphatic group having 1 to 10 carbon atoms, and And at least one substituent selected from the group consisting of unsaturated aliphatic groups, or at least one hydrogen. L1 includes an ester group, an ether group, a carbonyl group, a cyano group, a nitro group, a nitroxyl group, an alkyl group, a phenyl group, an alkylthio group, a sulfone group, or a sulfoxide group bonded to R31. As described above, L1 preferably contains an ester group, an ether group, or a carbonyl group that has a high affinity with an aprotic polar solvent. R33 is a divalent residue bonded to R32 and M1, and optionally has an alkylene group having 1 to 4 carbon atoms or an alkenylene having 1 to 4 carbon atoms which may have a substituent. And at least one selected from the group consisting of a group, an arylene group which may have a substituent, an ester group, an amide group and an ether group. M1 is represented by Formula (2), and is bonded to R33 by the above-described bond. n and m are integers representing the number of repeating monomer units.

  R31 and R32 may include side chains other than M1 and L1. As described above, m + n is preferably 4 or more, more preferably 10 or more, and further preferably 20 or more and 4000 or less. In order for the copolymer to have a high charge density and good affinity for an aprotic polar solvent, m / n is preferably greater than 0 and 5 or less. The repeating unit containing L1 (second unit) and the repeating unit containing M1 (first unit) may be regularly arranged or randomly arranged.

  Specifically, the polymer compound 14 may be a copolymer represented by the following formula (38) in which two repeating units are bonded to each other with a symbol *.

  In formula (38), R36 has a C1-C4 alkylene group which may have a substituent, a C1-C4 alkenylene group which may have a substituent, and a substituent. And a divalent residue containing at least one selected from the group consisting of an arylene group, an ester group, an amide group and an ether group. R34 and R35 each independently represent a hydrogen atom, a saturated aliphatic group having 1 to 4 carbon atoms or a phenyl group, and R37 to R39 each independently represent a chain aliphatic group or a cyclic aliphatic group. A group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, a nitroso group, or an alkylthio group, and R38 and R39 may be bonded to each other to form a ring. L1 is an ester group, ether group, carbonyl group, cyano group, nitro group, nitroxyl group, alkyl group, phenyl group, alkylthio group, sulfone group or sulfoxide group. As described above, since the tetrathiafulvalene skeleton is very stable even in an oxidized state, the functional group bonded to the skeleton does not significantly affect the redox reaction of the skeleton.

  The polymer compound 14 which is a copolymer composed of the first unit and the second unit may be synthesized by any method as long as the structure described above is obtained. For example, a copolymer main chain compound that becomes the main chain of the copolymer may be synthesized, and then a side chain structure including the structure represented by the formula (2) may be introduced into the copolymer main chain compound. Alternatively, a side chain structure including a structure represented by the formula (2) may be introduced in advance into a monomer body used for the synthesis of a copolymer main chain compound, and a copolymer may be synthesized using this monomer. In order to prevent the dislocation of active bonds in the polymerization reaction and synthesize a highly ordered copolymer with controlled molecular weight, mixing ratio of the first unit and the second unit, It is preferable to first synthesize a copolymer main chain compound and introduce a side chain structure including the structure represented by the formula (2) into the copolymer main chain compound by a coupling reaction. Examples of the coupling reaction include a coupling reaction using a halogen element and a hydroxyl group, a coupling reaction using a halogen element and an amino group, and the like. In this case, a halogen element is introduced into one of the copolymer main chain compound and the side chain structure, and a hydroxyl group or an amino group is introduced into the other. According to the coupling reaction with a halogen element and a hydroxyl group, a copolymer in which the copolymer main chain compound and the side chain structure including the structure represented by the formula (2) are bonded by an ester bond is obtained. According to the coupling reaction of the halogen element and the amino group, a copolymer in which the copolymer main chain compound and the side chain structure including the structure represented by the formula (2) are bonded by an amide bond is obtained. Alternatively, by introducing a hydroxyl group into both the copolymer main chain compound and the side chain structure and dehydrating and condensing the hydroxyl groups together, the side chain structure including the structure represented by the formula (2) is copolymerized. It may be introduced into the main chain compound. In this case, a copolymer in which the main chain of the copolymer and the side chain structure including the structure represented by the formula (2) are bonded by an ether bond is obtained.

  As described above, as a compound that can be used for the polymer compound 14, a polymer containing a tetrachalcogenofulvalene skeleton in the main chain repeating unit, a first unit having a tetrachalcogenofulvalene skeleton in the side chain, and the tetra A copolymer with a second unit having no chalcogenofulvalene skeleton in the side chain has been described. In these two types of polymer compounds 14, the tetrachalcogenofulvalene skeleton independently exhibits a redox reaction without depending much on the polymer structure of the polymer compound 14. For this reason, the redox potential of the tetrachalcogenofulvalene skeleton is almost equal in these two types of polymer compounds 14. Therefore, in the electrode 10 of this embodiment, either of these two types of polymers may be used as the polymer compound 14 which is an electrode active material, and both of these may be used.

  As the conductive particles 15, various electron conductive materials that do not cause a chemical change at the reaction potential of the electrode 10 can be used. Note that the conductive particles 15 are not dissolved in the electrolytic solution. When the electrode 10 of this embodiment is used as a positive electrode of a lithium secondary battery, examples of the conductive particles 15 include carbon materials such as carbon black, graphite, and carbon fiber, metal fibers, metal powders, conductive whiskers, Conductive metal oxides or the like can be used alone or as a mixture thereof.

  From the viewpoint that the energy density per weight can be increased, the conductive particles 15 are preferably composed of a particulate carbon material such as carbon black and / or carbon fibers. In order to increase the contact area between the polymer compound 14 and the electrolytic solution, it is desirable to use particulate carbon having a large specific surface area as the conductive particles 15.

  The active material layer 12 may include second conductive particles for assisting electronic conductivity in the electrode 10 as necessary. Increasing the electron conductivity in the electrode 10 by further including second conductive particles located between the aggregates 13 adjacent to each other and not covered with the polymer compound 14 Can do. Examples of the second conductive particles include carbon materials such as carbon black, graphite, and carbon fiber, metal fibers, metal powders, conductive whiskers, conductive metal oxides, and the like, and a mixture thereof is used. May be. The second conductive particles that assist the electronic conductivity in the electrode 10 may be the same as or different from the conductive particles 15 used in the aggregate 13.

The active material layer 12 may contain an electrode active material other than the polymer compound 14. As an electrode active material other than the polymer compound 14, for example, a material capable of inserting and extracting lithium ions is used. As a material capable of inserting and extracting lithium ions, a material known as a positive electrode material of a lithium ion battery can be used. Specifically, a transition metal oxide, a lithium-containing transition metal oxide, or the like can be used. Examples of the transition metal oxide include cobalt oxide, nickel oxide, manganese oxide, vanadium oxide represented by vanadium pentoxide (V ₂ O ₅ ), a mixture or composite oxide thereof. is there. As a positive electrode active material of a lithium ion battery, a lithium-containing transition metal oxide such as lithium cobaltate (LiCoO ₂ ) is best known. Further, as an electrode active material other than the polymer compound 14, a transition metal silicate, a transition metal phosphate represented by lithium iron phosphate (LiFePO ₄ ), or the like can also be used.

  As the current collector 11, for example, a known material can be used as a positive electrode current collector of a lithium secondary battery. The current collector 11 is, for example, a foil or mesh made of a metal such as aluminum, carbon, or stainless steel.

  As the binder 16, it is preferable to use a resin that is insoluble in an aprotic polar solvent. This is because when a resin that is insoluble in an aprotic polar solvent is used as the binder 16, either a wet method or a dry method can be employed to produce the electrode 10.

  On the other hand, when a resin soluble in an aprotic polar solvent is used as the binder 16, it is preferable to prepare the electrode 10 by a dry method. This is because when the resin soluble in the aprotic polar solvent is used as the binder 16 and the wet method is employed, the structure of the electrode 10 may not be realized. In the wet method, a slurry containing a solvent, a binder 16 and an agglomerate 13 is prepared, and the slurry is applied on the current collector 11 and dried to obtain the electrode 10. When preparing a slurry in which the binder 16 is dissolved, it is necessary to use an aprotic polar solvent as the solvent, but the aprotic polar solvent can also dissolve the polymer compound 14. Therefore, when a slurry is prepared using an aprotic polar solvent as a solvent, the polymer compound 14 in the aggregate 13 is dissolved in the aprotic polar solvent, and the structure of the aggregate 13 is not maintained in the slurry. Ten structures may not be obtained. However, as will be apparent to those skilled in the art, it is assumed that the binder 16 does not elute into the electrolyte solution 29.

  Specifically, the binder 16 is at least selected from the group consisting of water-soluble resins such as polyacrylic acid and copolymers thereof, fluorine resins such as polytetrafluoroethylene, and rubber resins such as styrene butadiene rubber. Preferably one is included.

  As a manufacturing method of the electrode 10, a well-known method can be used as a manufacturing method of the electrode of a lithium secondary battery, for example. However, as can be seen from the above description, when the electrode 10 is produced using a wet method including a step of preparing a slurry, the polymer compound 14 in the aggregate 13 needs not to be dissolved in the solvent in the slurry. For example, the electrode 10 can be produced by preparing a slurry containing styrene-butadiene rubber as the binder 16, water as a solvent, and the aggregate 13, and applying and drying. Alternatively, the electrode 10 can be obtained by kneading the binder 16 such as polytetrafluoroethylene and the aggregate 13 and press-bonding them on the current collector 11.

  The thickness of the active material layer 12 is not particularly limited, but is preferably 100 to 1000 μm from the viewpoint of easy realization of a high-capacity electricity storage device and design.

  FIG. 3 is a schematic cross-sectional view showing a coin-type lithium secondary battery which is an embodiment of the electricity storage device according to the present invention. A coin-type lithium secondary battery 20 shown in FIG. 3 includes a positive electrode 31, a negative electrode 32, and a separator 24. In the present embodiment, the electrode 10 described above is used as the positive electrode 31. The positive electrode 31 includes a positive electrode active material layer 23 and a positive electrode current collector 22, and the positive electrode active material layer 23 is supported on the positive electrode current collector 22. The detailed configuration of the positive electrode 31 is as described above for the electrode 10. The negative electrode 32 includes a negative electrode active material layer 26 and a negative electrode current collector 27, and the negative electrode active material layer 26 is supported on the negative electrode current collector 27. The positive electrode 31 and the negative electrode 32 are opposed to each other with the separator 24 interposed therebetween so that the positive electrode active material layer 23 and the negative electrode active material layer 26 are in contact with the separator 24, thereby constituting an electrode group. The electrode group is housed in a space inside the case 21. An electrolytic solution 29 is injected into the space inside the case 21, and the positive electrode 31, the negative electrode 32, and the separator 24 are impregnated with the electrolytic solution 29. The opening of the case 21 is sealed with a sealing plate 25 using a gasket 28.

  The negative electrode active material layer 26 includes a negative electrode active material. As the negative electrode active material, a known negative electrode active material that reversibly occludes and releases lithium is used. Examples of the negative electrode active material include graphite materials such as natural graphite and artificial graphite, amorphous carbon materials, lithium metal, lithium-containing composite nitride, lithium-containing titanium oxide, silicon, silicon-containing alloys, silicon oxide, and tin Materials capable of reversibly occluding and releasing lithium, such as tin-containing alloys and tin oxides; carbon materials having electric double layer capacity such as activated carbon; organic compound materials having π-electron conjugated clouds; etc. Can be used. As the negative electrode active material, a single material may be used, or a plurality of materials may be mixed and used. The negative electrode active material layer 26 may include only the negative electrode active material, or may include a conductive agent and / or a binder. As the conductive agent and the binder, the materials described above can be used.

  For the negative electrode current collector 27, for example, a material known as a current collector for a negative electrode for a lithium ion secondary battery, such as copper, nickel, and stainless steel, can be used. Similar to the positive electrode current collector 22, the negative electrode current collector 27 can have a form such as a metal foil, a metal mesh, a resin film containing a conductive filler made of metal, and the like.

  The separator 24 includes a fine space, and an electrolytic solution 29 is held in the fine space. The separator 24 is a resin layer made of a resin that does not have electronic conductivity, and is a microporous film that has a large ion permeability and has a predetermined mechanical strength and electrical insulation. From the viewpoint of excellent organic solvent resistance and hydrophobicity, the material of the separator 24 is preferably a polyolefin resin made of single polypropylene, polyethylene, or a combination thereof. Instead of the separator 24, a resin layer having an electronic conductivity that swells with the electrolyte solution 29 and functions as a gel electrolyte may be provided.

  The electrolytic solution 29 is a non-aqueous electrolytic solution composed of a non-aqueous solvent and a supporting salt dissolved in the non-aqueous solvent. As the non-aqueous solvent, a known aprotic polar solvent that can be used for a non-aqueous secondary battery or a non-aqueous electric double layer capacitor can be used. Specifically, as the non-aqueous solvent, a solvent containing a cyclic carbonate can be suitably used. This is because the cyclic carbonate has a very high dielectric constant, as represented by ethylene carbonate and propylene carbonate. Among the cyclic carbonates, propylene carbonate is preferable. This is because propylene carbonate has a freezing point of −49 ° C., which is lower than that of ethylene carbonate, and the electricity storage device can be operated even at a low temperature. As the non-aqueous solvent, a solvent containing a cyclic ester can also be suitably used. This is because the cyclic ester has a very high dielectric constant as represented by γ-butyrolactone. By including these components, the non-aqueous solvent of the electrolyte solution 29 can have a very high dielectric constant as a whole. In addition to the solvents described above, chain carbonates, chain esters, cyclic or chain ethers, and the like can be used as non-aqueous solvents. Specifically, nonaqueous solvents such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, acetonitrile, dimethyl sulfoxide, and the like can be used. As the non-aqueous solvent, only one of the above-mentioned solvents may be used, or a plurality of the solvents may be mixed and used.

  As the supporting salt, salts composed of anionic species and cationic species described below can be used. As anion species, halide anion, perchlorate anion, trifluoromethanesulfonate anion, tetrafluoroborate anion, hexafluorophosphate anion, trifluoromethanesulfonate anion, nonafluoro-1-butanesulfonate anion, bis (Trifluoromethanesulfonyl) imide anion, bis (perfluoroethylsulfonyl) imide anion, and the like can be used. Examples of the cation species include alkali metal cations such as lithium, sodium and potassium; alkaline earth metal cations such as magnesium; quaternary ammonium cations represented by tetraethylammonium and 1,3-ethylmethylimidazolium; it can.

  As the cationic species, a quaternary ammonium cation and a lithium cation are preferable. Since the quaternary ammonium cation has high ion mobility, an electrolytic solution having high conductivity can be obtained by using a quaternary ammonium cation as a cation species. When a quaternary ammonium cation is used as the cation species, a negative electrode having an electric double layer capacity and a high reaction rate, such as activated carbon, can be used. Therefore, a high-output electricity storage device can be obtained by using a quaternary ammonium cation as the cation species. When a lithium cation is used as the cation species, a negative electrode that has a low reaction potential and a high capacity density and can occlude and release lithium can be used. Therefore, by using a lithium cation as the cation species, a power storage device having a high voltage and a high energy density can be obtained.

  In the present embodiment, the case where the electrode and the electricity storage device of the present invention are applied to a lithium secondary battery has been described. However, the electrode and the electricity storage device of the present invention are not limited to lithium secondary batteries, and can be used for various energy storage devices and sensors that use electrochemical charge storage. Specifically, an electric double layer capacitor may be configured using the electrode of the present invention as a positive electrode and activated carbon as a negative electrode. Or you may comprise electrochemical capacitors other than a secondary battery, such as a lithium ion capacitor, using the negative electrode which can occlude and discharge | release lithium, such as lithium occlusion graphite.

  The electrode of the present invention can also be suitably used as an electrode used for various electrochemical devices. For example, a polymer actuator can be configured by using, as an electrolyte, a polymer gel electrolyte that expands and contracts with charge and discharge. In the electrode of the present invention, the polymer compound as an active material contains a tetrachalcogenofulvalene skeleton, so that the color changes with charge and discharge. From this, an electrochromic display element can be comprised by using transparent conductive glass as an electrical power collector, and using transparent materials, such as a film and glass, for some exteriors.

  Hereinafter, embodiments of the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to the examples.

Example 1
[1. Synthesis of polymer compound containing tetrachalcogenofulvalene skeleton in repeating unit]
As a polymer compound containing a tetrachalcogenofulvalene skeleton as a repeating unit, a first unit having a redox site in the side chain and a second unit having no redox site in the side chain, represented by the following formula (39): A copolymer (hereinafter referred to as copolymer [39]) was synthesized.

  In the copolymer [39] represented by the formula (39), the component ratio m / n of the unit number m of the second unit to the unit number n of the first unit is about 1. The synthesis of the copolymer [39] includes the synthesis of a tetrathiafulvalene derivative introduced into the side chain, the synthesis of the copolymer main chain compound, and the coupling of the tetrathiafulvalene derivative to the copolymer main chain compound. Done in stages. Hereinafter, these will be described in order.

The synthesis of the tetrathiafulvalene derivative was performed by the route shown in the following formula (40). 5 g of tetrathiafulvalene [40a] (manufactured by Aldrich) was added to the flask, and 80 mL of tetrahydrofuran (manufactured by Aldrich) was further added. After cooling this to -78 ° C., 20 mL of an n-hexane-tetrahydrofuran solution of lithium diisopropylamide (manufactured by Kanto Chemical Co., Ltd., concentration 1 mol / L) was added dropwise over 10 minutes. Thereafter, 7.3 g of paraformaldehyde (manufactured by Kanto Chemical Co., Inc.) was added and the reaction was allowed to proceed by stirring for 15 hours. The solution after the reaction was poured into 900 mL of water, extracted with 1 L of diethyl ether (manufactured by Kanto Chemical Co., Ltd.) twice, washed with 500 mL of saturated aqueous ammonium chloride solution and 500 mL of saturated brine, and then anhydrous sodium sulfate Dried by. After removing the desiccant, 6.7 g of a crude product obtained by concentration under reduced pressure was purified with a silica gel column to obtain 1.7 g of a purified product. It was confirmed by ¹ H-NMR and IR that the purified product was a tetrathiafulvalene derivative [40c] shown on the right side of the formula (40).

The synthesis of the copolymer main chain compound was carried out by the route shown in the following formula (41). As the monomer material, mixing the 21g of methacrylonitrile Lee Rukuroraido [41a] (Aldrich Co.) and 40g of methyl methacrylate [41b] (Aldrich Co.) in 90g of toluene (Aldrich Corp.) as a polymerization initiator, 4 g of azoisobutyronitrile (Aldrich) was added. The reaction was allowed to proceed by stirring the mixture at 100 ° C. for 4 hours. Hexane was added to the solution after the reaction to perform reprecipitation, thereby obtaining 57 g of a precipitated product. It was confirmed by ¹ H-NMR, IR and gel permeation chromatography (GPC) that the product was a copolymer main chain compound [41c] shown on the right side of the formula (41).

The copolymer main chain compound [41c] is composed of a unit having a Cl group and a unit having a methoxy group. As a result of ¹ H-NMR measurement in a chloroform solvent, the peak derived from the methyl group directly bonded to the main chain of the copolymer main chain compound [41c] is around 0.5 to 2.2 ppm, and the side chain is A peak derived from the methoxy group was observed at around 3.6 ppm. In addition, the component ratio m / n of the unit having a methoxy group to the unit having a Cl group in the copolymer main chain compound [41c] can be calculated from the ratio of the integrated values of these peaks. As a result of IR measurement for the copolymer main chain compound [41c], the carbonyl group (C═O) and Cl group (C—Cl) of the unit having a Cl group and the carbonyl group (C═ Each of O) appeared as a different absorption peak. As a result of measurement by GPC, the degree of polymerization of the copolymer main chain compound [41c] exceeded 20.

Coupling of the tetrathiafulvalene derivative [40c] to the copolymer main chain compound [41c] was carried out by the route represented by the following formula (42). Under an Ar gas stream, 1.0 g of tetrathiafulvalene derivative [40c] and 26 mL of tetrahydrofuran were placed in a reaction vessel and stirred at room temperature. To this reaction solution, 0.17 g of NaH (60 wt% in mineral oil) (manufactured by Aldrich) was added dropwise and stirred at 40 ° C. for 1 hour, and 0.58 g of the copolymer main chain compound was added to 8.5 mL of tetrahydrofuran. A solution in which [41c] was dissolved was added. The reaction was allowed to proceed by stirring the resulting mixture at 70 ° C. overnight. Hexane was added to the solution thus obtained, and 0.2 g of a precipitated product was obtained by reprecipitation. It was confirmed by ¹ H-NMR, IR and GPC that the product was a copolymer [39] shown on the right side of the formula (42).

As a result of ¹ H-NMR measurement, the peak derived from the methylene group bonding the main chain of the copolymer [39] and the tetrathiafulvalene group was around 4.8 ppm, and the peak derived from the tetrathiafulvalene group was 6 It was observed in the vicinity of .8 to 7.0 ppm. The copolymer [39] is composed of a first unit having a tetrathiafulvalene group and a second unit having a methoxy group. ^From the ratio of the integrated value of each peak obtained by ¹ H-NMR measurement, the constituent ratio m / n of the second unit to the first unit in the copolymer [39] was calculated by the same method as described above. The composition ratio m / n was approximately 1. The weight average molecular weight of the copolymer [39] was approximately 28,000. That is, in the copolymer [39], it was confirmed that the first unit number n was 72, and the degree of polymerization (the sum of n and m) was 144, which was 4 or more. As a result of elemental sulfur analysis on the copolymer [39], the sulfur content of the copolymer [39] was 30.2 wt%. The theoretical capacity of the copolymer [39] calculated from the sulfur content was 125 mAh / g.

[2. Production of aggregates]
Particles (aggregates) in which a polymer compound having a tetrachalcogenofulvalene skeleton as a repeating unit coats at least a part of the surface of conductive particles were produced by the method described below.

  First, 3.0 g of the copolymer [39] is pulverized in a mortar, 15.0 g of N-methylpyrrolidone (NMP) (manufactured by Wako Pure Chemical Industries, Ltd.) is added as a solvent, and the mixture is kneaded in the mortar. The polymer [39] was dissolved in a solvent. The particle size distribution of the copolymer [39] in the obtained NMP solution was measured by a laser diffraction / scattering method using SALD-7000 manufactured by Shimadzu Corporation. The measurement was performed while stirring the NMP solution using the attached stirring plate under the measurement conditions in which the measurement particle size range was 0.015 μm to 500 μm and the measurement interval was 2 seconds. As a result of the measurement, no diffraction / scattering intensity was observed, and it was confirmed that there were no particles of 0.015 μm or more in the NMP solution. Furthermore, as a result of the ultraviolet-visible absorption spectrum (UV-vis) measurement for the NMP solution, an absorption peak derived from the TTF ring was confirmed in the vicinity of 300 to 320 nm, and the copolymer [39] was present in the NMP solution. Was confirmed.

  By adding 3.0 g of acetylene black, which is conductive particles, and 39 g of NMP to the NMP solution in which the copolymer [39] is dissolved, and kneading, the copolymer [39] and the conductive particles are contained. An active material slurry was prepared. The ratio of copolymer [39] and carbon black in the active material slurry was 50:50 by weight.

  By introducing the obtained active material slurry into a spray dryer (spray dryer B290 manufactured by Nihon Büch) and removing the solvent under conditions of a liquid feed amount of 3 mL / min and a drying gas temperature of 220 ° C. (nitrogen gas), Aggregates (polymer-coated particles) were obtained.

  As a result of elemental analysis of the obtained aggregate, the sulfur content was 15.1 wt%. From this, the ratio of the copolymer [39] and acetylene black in the obtained aggregate was the same as the ratio in the active material slurry before spray drying.

  In order to grasp the distribution state of the copolymer [39] in the obtained aggregate, the cross section of the sample obtained by mixing the aggregate with resin and solidifying it was observed at a magnification of 40000 times, and Auger electron spectroscopy. (AES, ULVAC-PHI, Inc. Model 670) was used for elemental analysis. 4A shows a cross-sectional SEM image of the analysis region, and FIGS. 4B and 4C show a carbon distribution image and a sulfur distribution image of the analysis region corresponding to the cross-sectional SEM image. In FIG. 4B, a region where carbon is present is displayed in monochrome gradation, a portion where there is a lot of carbon is shown in white, and a region where no carbon is present is shown in black. In FIG. 4C, a region where sulfur is present is displayed in monochrome gradation, a portion where there is much sulfur is shown in white, and a region where no sulfur is present is shown in black. From FIG. 4 (a), it was confirmed that the agglomerates were present as particles of about 4 μm and had some voids inside. From FIG.4 (b), distribution of the carbon originating in electroconductive particle has been confirmed. From FIG.4 (c), distribution of the sulfur originating in the copolymer [39] which is an electrode active material has been confirmed. 4 (b) and 4 (c), sulfur is distributed so as to substantially overlap the carbon distribution, that is, the copolymer [39] elemental sulfur is distributed so as to cover the conductive particles. I was able to confirm. As described above, in Example 1, an aggregate in which the copolymer [39], which is an electrode active material, coats the conductive particles was obtained.

[3. Preparation of positive electrode]
To 30 mg of the obtained aggregate, 96 mg of acetylene black as the second conductive particles was added and mixed uniformly, and further 24 mg of polytetrafluoroethylene was added and mixed to obtain a positive electrode mixture. This positive electrode mixture was pressure-bonded onto an aluminum metal mesh as a positive electrode current collector, and vacuum-dried to form a positive electrode active material layer. This was punched into a disc shape having a diameter of 13.5 mm to produce a positive electrode. The cross section of the produced positive electrode was observed with an electron microscope and an electron beam microanalyzer (EPMA), and the distribution of sulfur derived from the copolymer [39] was measured. As a result of EPMA, it was observed that sulfur was distributed in a granular form from 2 μm to a maximum of about 10 μm. From this, it was confirmed that the aggregates exist in the same shape as in the positive electrode before the positive electrode was manufactured. The thickness of the active material layer in the produced positive electrode was 200 μm. The weight of the active material layer per unit area of the positive electrode was 0.1 mg / cm ² . The weight ratio of the positive electrode active material (copolymer [39]) to the positive electrode was 10 wt%.

[4. Fabrication of coin-type electricity storage device]
A coin-type electricity storage device having the structure shown in FIG. 3 was produced using the produced positive electrode. First, the positive electrode was placed in the case so that the positive electrode current collector was in contact with the inner surface of the case, and a separator made of a porous polyethylene sheet was placed thereon. Next, a nonaqueous electrolytic solution was poured into the case. As the nonaqueous electrolytic solution, an electrolytic solution in which lithium hexafluorophosphate was dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate and ethyl methyl carbonate in a weight ratio of 1: 3 was used. The negative electrode was disposed so that the negative electrode active material layer was in contact with the separator. With the electrolyte solution impregnated in all of the positive electrode, the separator, and the negative electrode, the opening of the case was sandwiched by a sealing plate equipped with a gasket and sealed by a press machine to obtain a coin-type electricity storage device.

Here, the negative electrode was produced as follows. First, a copper foil having a thickness of 20 μm was used as a negative electrode current collector, and a layer made of graphite having a thickness of 40 μm was formed thereon by coating as a negative electrode active material layer. This was punched into a disc shape having a diameter of 13.5 mm to obtain a graphite electrode. The obtained graphite electrode was subjected to preliminary charge and discharge for 3 cycles at a current value of 0.4 mA / cm ² between 0 V and 1.5 V (lithium reference potential) using Li metal as a counter electrode. Thereby, it was confirmed that the graphite electrode has a reversible capacity of 1.6 mAh / cm ² per unit area and can be reversibly charged and discharged. A graphite electrode charged to 70% of the reversible capacity, that is, pre-doped with lithium, was used as the negative electrode. The same electrolyte solution and separator as those used for the coin-type electricity storage device were used for charging and discharging the graphite electrode and pre-doping with lithium.

(Example 2)
[1. Synthesis of polymer containing tetrachalcogenofulvalene skeleton in repeating unit]
A copolymer [39] was synthesized in the same manner as in Example 1.

[2. Production of aggregates]
Particles (aggregates) in which a polymer compound having a tetrachalcogenofulvalene skeleton as a repeating unit coats at least a part of the surface of conductive particles were produced by the method described below.

  First, 0.66 g of the copolymer [39] is pulverized in a mortar, 2.4 g of NMP (manufactured by Wako Pure Chemical Industries, Ltd.) is added as a solvent, and the copolymer [39] is kneaded in the mortar. Dissolved in solvent. The particle size distribution of the copolymer [39] in the obtained NMP solution was measured by a laser diffraction / scattering method using SALD-7000 manufactured by Shimadzu Corporation. The measurement was performed while stirring the NMP solution using the attached stirring plate under the measurement conditions in which the measurement particle size range was 0.015 μm to 500 μm and the measurement interval was 2 seconds. As a result of the measurement, no diffraction / scattering intensity was observed, and it was confirmed that there were no grains of 0.015 μm or more in the NMP solution. Furthermore, as a result of ultraviolet-visible absorption spectrum (UV-vis) measurement for the NMP solution, the copolymer [39] is present in the NMP solution by confirming an absorption peak derived from the TTF ring in the vicinity of 300 to 320 nm. It was confirmed that

  By adding 5.34 g of acetylene black as conductive particles and 51.6 g of NMP to the NMP solution in which the copolymer [39] is dissolved, and kneading the mixture, the copolymer [39] and the conductive particles An active material slurry containing was produced. The ratio of the copolymer [39] and carbon black in the active material slurry is 11:89 by weight.

  By introducing the obtained active material slurry into a spray dryer (spray dryer B290 manufactured by Nihon Büch) and removing the solvent under conditions of a liquid feed amount of 3 mL / min and a drying gas temperature of 220 ° C. (nitrogen gas), Aggregates (polymer-coated particles) were obtained.

[3. Preparation of positive electrode]
A positive electrode mixture was obtained by adding and mixing 15 mg of polytetrafluoroethylene to 135 mg of the obtained aggregate. This positive electrode mixture was pressure-bonded onto an aluminum wire mesh as a positive electrode current collector and vacuum dried to form a positive electrode active material layer. This was punched into a disc shape having a diameter of 13.5 mm to produce a positive electrode. The thickness of the active material layer in the produced positive electrode was 200 μm. The weight of the active material layer per unit area of the positive electrode was 0.1 mg / cm ² . The weight ratio of the positive electrode active material (copolymer [39]) to the positive electrode was 10 wt%.

[4. Production of electricity storage device]
A coin-type electricity storage device was produced under the same conditions as in Example 1 except that the obtained positive electrode was used as the positive electrode.

(Comparative Example 1)
[1. Synthesis of polymer containing tetrachalcogenofulvalene skeleton in repeating unit]
A copolymer [39] was synthesized in the same manner as in Example 1.

[2. Preparation of positive electrode]
20 mg of the copolymer [39] synthesized in the same manner as in Example 1 was pulverized in a mortar, 144 mg of acetylene black was added and mixed uniformly, and further 36 mg of polytetrafluoroethylene was added and mixed to obtain a positive electrode mixture. Obtained. Here, the particle size of the copolymer [39] crushed in the mortar was about 5 to 20 μm. This positive electrode mixture was pressure-bonded onto an aluminum wire mesh as a positive electrode current collector and vacuum dried to form a positive electrode active material layer. This was punched into a disc shape having a diameter of 13.5 mm to produce a positive electrode. The thickness of the positive electrode active material layer of the produced positive electrode was 200 μm. The weight of the active material layer per unit area of the positive electrode was 0.1 mg / cm ² . The weight ratio of the positive electrode active material (copolymer [39]) to the positive electrode was 10 wt%.

[3. Fabrication of coin-type electricity storage device]
A coin-type electricity storage device was produced under the same conditions as in Example 1 except that the obtained electrode was used as the positive electrode.

(Evaluation of electricity storage devices)
Charge / discharge capacity evaluation and output evaluation were performed on the electricity storage devices obtained in Examples 1 and 2 and Comparative Example 1.

  The charge / discharge capacity of the electricity storage device is obtained by dividing the charge / discharge capacity at the first charge / discharge by the active material weight (weight of copolymer [39] in the positive electrode), that is, charge / discharge capacity per unit weight of the active material. Evaluated by. In addition, charging / discharging was performed with the constant current of 0.2 mA, the charge upper limit voltage was set to 3.9V, and the discharge minimum voltage was set to 2.9V. The rest time from the end of charging to the start of the next discharge was set to zero.

  The output of the electricity storage device was evaluated based on the capacity maintenance ratio at the time of constant current discharge of 10 mA with respect to the constant current discharge of 0.2 mA. That is, after the charge / discharge capacity was measured, the electricity storage device was charged with a constant current of 0.2 mA, and then discharged with a constant current of 10 mA to obtain the discharge capacity (large current charge / discharge capacity). A value obtained by dividing the discharge capacity at the time of constant current discharge of 10 mA by the discharge capacity at the time of constant current discharge of 0.2 mA was defined as a capacity retention rate. In addition, at the time of charging / discharging, the charge upper limit voltage was 3.9V, and the discharge lower limit voltage was 2.5V.

  Table 1 summarizes the results of charge and discharge capacity evaluation and output evaluation for the electricity storage devices of Examples 1 and 2 and Comparative Example 1.

  As shown in Table 1, in each of the electricity storage devices obtained in Examples 1 and 2 and Comparative Example 1, the charge / discharge capacity at the time of 0.2 mA charge / discharge was close to the theoretical capacity. From this, it was confirmed that in any power storage device, the electrode active material contained in the electrode was reversibly charged and discharged.

  Compared to Comparative Example 1, in Example 2, the capacity retention rate during 10 mA charge / discharge was higher. This is considered to be due to the fact that, in Example 2, the polymer compound as the positive electrode active material coats the surface of the conductive particles in the form of a thin film, so that the resistance during oxidation and reduction is reduced. Furthermore, in Example 1, the capacity retention rate during 10 mA charge / discharge was higher than that in Example 2. This is considered to be due to the following reason. That is, the positive electrode active material layer in the positive electrode used in Example 2 was formed only with aggregates and a binder. On the other hand, in Example 1, since the second conductive particles not covered with the polymer compound were present in the positive electrode active material layer together with the aggregates, more conductive paths than in Example 2 were obtained. Is considered to have been formed in the positive electrode. Therefore, it is considered that the electronic resistance during charging / discharging was reduced and the capacity retention rate during 10 mA charging / discharging was increased.

  From the above, it was confirmed that a high-output power storage device can be realized by using the electrode of the present invention.

DESCRIPTION OF SYMBOLS 10 Electrode 11 Current collector 12 Electrode active material layer 13 Aggregate 13a Void 14 Polymer compound 15 Conductive particle 16 Binder 20 Coin type lithium secondary battery 22 Positive electrode current collector 23 Positive electrode active material layer 24 Separator 26 Negative electrode active Material layer 27 Negative electrode current collector 29 Electrolytic solution 31 Positive electrode 32 Negative electrode

Claims (13)

A current collector,
An active material layer including an electrode active material, conductive particles, and a binder, and provided on the current collector;
With
The electrode active material is a polymer compound having a tetrachalcogenofulvalene skeleton in a repeating unit,
In the active material layer, the electrode active material and the conductive particles form an aggregate of the conductive particles coated with the electrode active material,
The aggregate substantially consists of the electrode active material, the conductive particles, and internal voids,
The electrode, wherein the binder is present between the adjacent aggregates.   The electrode according to claim 1, wherein the aggregate does not contain the binder.   The electrode according to claim 1, wherein the conductive particles are made of carbon black. The active material layer is
4. The apparatus according to claim 1, further comprising second conductive particles that are located between the aggregates adjacent to each other and the aggregates and are not covered with the polymer compound. 5. Electrodes.   The electrode according to any one of claims 1 to 4, wherein the thickness of the active material layer is in a range of 100 to 1000 µm.   The electrode according to claim 1, wherein the binder is a resin that is insoluble in an aprotic polar solvent.   The electrode according to claim 6, wherein the binder contains at least one selected from the group consisting of a water-soluble resin, a fluororesin, and a rubber-based resin.   The electrode according to any one of claims 1 to 7, wherein the polymerization degree of the polymer compound is 4 or more.   The electrode according to any one of claims 1 to 8, wherein the polymer compound is a polymer compound containing a tetrachalcogenofulvalene skeleton in the main chain.   The electrode according to any one of claims 1 to 8, wherein the polymer compound is a polymer compound containing a tetrachalcogenofulvalene skeleton in a side chain. A positive electrode comprising the electrode according to claim 1;
A negative electrode containing a negative electrode active material capable of inserting and extracting lithium ions;
An electrolyte solution containing a salt of the lithium ion and anion and filled between the positive electrode and the negative electrode;
An electricity storage device comprising: Preparing an active material slurry comprising conductive particles, a polymer compound having a tetrachalcogenofulvalene skeleton in a repeating unit, and a solvent capable of dissolving the polymer compound;
Removing the solvent from the active material slurry so as to obtain an aggregate of the conductive particles coated with the polymer compound;
Forming an active material layer on a current collector using the aggregate and the binder;
A method for producing an electrode, comprising:   The method for producing an electrode according to claim 12, wherein the step of removing the solvent includes a step of removing the solvent from the active material slurry by spray drying.