JP2016192279A - Aqueous pseudo solid secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery from which electrolyte never leaks outside from a battery case, even if broken during use, as the secondary battery using a safe gelatinous aqueous electrolyte, while having excellent cycle characteristic.SOLUTION: The present invention relates to an aqueous secondary battery comprising a positive electrode including a metallocene compound as an active material, a negative electrode including an orthoquinone compound as an active material, and a gelatinous aqueous electrolyte.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous quasi-solid secondary battery.

  In recent years, secondary batteries have been widely used as power sources for IT devices such as mobile phones and notebook computers and electric vehicles. In particular, lithium ion secondary batteries are widely used from the viewpoints of high battery characteristics such as electromotive force, energy density, charge / discharge energy efficiency, and low self-discharge. In a lithium ion secondary battery, for example, a non-aqueous electrolyte solution containing an organic solvent is used as an electrolyte solution in order to enable high-voltage charge / discharge, and a lithium transition metal is used for either a positive electrode or a negative electrode as an electrode. An oxide or the like is used. Further, as a lithium ion secondary battery having further improved battery characteristics, an electrode active material containing a tetraketone compound is used as an electrode (Patent Document 1).

  On the other hand, since the non-aqueous electrolyte used for a lithium ion secondary battery contains an organic solvent, it is inflammable and harmful to the human body. Therefore, as a technology to improve the safety of lithium ion secondary batteries that use non-aqueous electrolytes, a technology that uses aqueous electrolytes and a technology that eliminates the risk of liquid leakage by gelling this aqueous electrolyte are developed. (Patent Documents 2 and 3).

International Publication No. 2011/111401 Japanese Patent Laid-Open No. 2001-102086 Japanese Patent Laid-Open No. 2001-210359

  However, a lithium ion secondary battery using a gelled aqueous electrolyte solution has the disadvantage that the cycle characteristics are insufficient, although the safety can be improved.

  Therefore, the present invention is a secondary battery using a safe gel-like aqueous electrolyte that does not leak out of the battery casing even if it is damaged during use, and has excellent cycle characteristics. Another object is to provide a secondary battery.

  The gist of the present invention for solving the above problems is as follows.

  An aqueous secondary battery comprising: a positive electrode including a metallocene compound as an active material; a negative electrode including an orthoquinone compound as an active material; and a gelled aqueous electrolyte.

  An aqueous secondary battery obtained by adding the gelling agent to the aqueous electrolytic solution.

  An aqueous secondary battery in which the gelling agent is a water-soluble gelling agent.

  An aqueous secondary battery, wherein the gelling agent is at least one compound selected from the group consisting of sodium carboxymethylcellulose and sodium alginate.

  An aqueous secondary battery in which at least one of the positive electrode and the negative electrode contains a conductive additive of a porous carbon material.

  An aqueous secondary battery in which the electrolyte contains at least one salt selected from the group consisting of a salt of an alkali metal element and a salt of a Group 2 element.

  The aqueous secondary battery in which the electrolyte contains a sodium salt.

  An aqueous secondary battery in which the metallocene compound is ferrocene.

  An aqueous secondary battery, wherein the orthoquinone compound is at least one compound selected from 9,10-phenanthrenequinone, dibromoorthoquinone, dichloroorthoquinone, difluoroorthoquinone, and diiodoorthoquinone.

  The aqueous secondary battery of the present invention is safe even if it is damaged in use by using a gel-like aqueous electrolyte. In addition, the secondary battery of the present invention can reduce the decrease in battery capacity due to self-discharge by gelling the aqueous electrolyte, and can further improve the cycle characteristics. In addition, by using a metallocene compound for the positive electrode and an orthoquinone compound for the negative electrode as active materials, a secondary battery with higher output and higher charge / discharge cycle characteristics can be provided.

It is a figure which shows schematic structure of the water-system secondary battery which is one Embodiment of this invention.

Hereinafter, the water-based secondary battery of the present invention will be described in detail.
The aqueous secondary battery of the present invention includes a positive electrode containing a metallocene compound as an active material, a negative electrode containing an orthoquinone compound as an active material, and a gelled aqueous electrolyte. In addition to these, other configurations may be provided as necessary as long as the above-described problems can be solved. Each will be described below.

[Structure of water-based secondary battery]
First, the shape and structure of an embodiment of the aqueous secondary battery of the present invention will be described with reference to FIG. The aqueous secondary battery 10 of the present embodiment includes a positive electrode sheet 13 in which a positive electrode active material layer 12 containing a metallocene compound is formed on a positive electrode current collector 11 and a negative electrode active material layer containing an orthoquinone compound on the surface of the negative electrode current collector 14. 17, a separator 19 provided between the positive electrode sheet 13 and the negative electrode sheet 18, and a gel-like aqueous electrolyte 20 between the positive electrode sheet 13 and the negative electrode sheet 18. is there. In this aqueous secondary battery 10, the separator 19 is sandwiched between the positive electrode sheet 13 and the negative electrode sheet 18, and these are wound and inserted into the cylindrical case 22, and the positive electrode terminal 24 and the negative electrode sheet 18 connected to the positive electrode sheet 13. And a negative electrode terminal 26 connected to each other. The positive electrode sheet 13 of this embodiment is an example of the positive electrode of the present invention. The negative electrode sheet 18 of this embodiment is an example of the negative electrode of the present invention. In the water-based secondary battery of the present embodiment, the case containing the positive electrode sheet 13, the negative electrode sheet 18, and the gel-like aqueous electrolyte 20 is a cylindrical shape using the cylindrical case 22. May be. There are various types of cases such as a laminate type and a coin type. Examples of the shape include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a square type. Moreover, you may apply to the large sized thing etc. which are used for an electric vehicle etc.

  As the material of the positive electrode current collector 11 and the negative electrode current collector 14, a material that does not cause a side reaction at the potentials of the positive electrode and the negative electrode is used. More specifically, the positive electrode current collector 11 and the negative electrode current collector 14 may be made of a material having corrosion resistance that does not cause a reaction such as dissolution at the potential of the positive electrode and the negative electrode. As a material of the positive electrode current collector 11 and the negative electrode current collector 14, for example, a metal material, an alloy, a carbon material, an inorganic conductive oxide material, or the like can be used. Examples of the metal material include copper, nickel, brass, zinc, aluminum, stainless steel, tungsten, gold, and platinum. The alloy is, for example, SUS. Examples of the carbon material include graphite, hard carbon, and glassy carbon.

(Negative electrode active material)
The negative electrode of the aqueous secondary battery shown in the negative electrode sheet 18 of FIG. 1 described above is formed, for example, by providing a negative electrode active material layer containing a negative electrode active material on a negative electrode current collector. The negative electrode active material of the water-based secondary battery includes an orthoquinone compound. Here, the orthoquinone compound refers to a compound having an aromatic ring containing an orthoquinone structure having two adjacent carbonyl groups.

  As the orthoquinone compound, an oligomer containing a structural unit derived from a compound represented by the following formula (1) or a compound represented by the following formula (1) is preferable.

In the formula (1), R ^{1 to} R ⁴ are each independently a hydrogen atom, a halogen atom, a heterocyclic group, an amino group, a nitro group, a formyl group, a cyano group, a hydroxy group, an alkoxy group, a thiol group, An alkylthio group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, or a hydrocarbon group; The heterocyclic group, amino group, alkoxy group, alkylthio group, alkylcarbonyl group, arylcarbonyl group, alkylsulfonyl group, arylsulfonyl group, and hydrocarbon group may be substituted. Any two or more groups of R ^{1 to} R ⁴ may be combined to form an optionally substituted ring structure together with the carbon atom to which each is bonded. In addition, it is preferable that the number of carbon atoms contained in the groups R ^{1 to} R ⁴ is small.

Examples of the halogen atom of R ^{1 to} R ⁴ in the formula (1) include fluorine, chlorine, bromine, iodine and the like. Of these, chlorine and bromine are preferable, and bromine is more preferable.

  Examples of the heterocyclic group include pyridyl group, pyrimidyl group, furyl group, chenyl group, tetrahydrofuryl group, dioxolanyl group, benzoxazol-2-yl group, tetrahydropyranyl group, pyrrolidyl group, imidazolicyl group, pyrazolysyl group, thiazolysyl group 5- to 6-membered aromatic heterocyclic groups containing a nitrogen atom, an oxygen atom, a sulfur atom, etc. as a heteroatom such as a group, inch azolysyl group, oxazolyl group, isoxazolyl group, piperidyl group, piperazyl group, morpholinyl group and the like Group heterocyclic group.

  The alkyl group, alkenyl group and alkynyl group may be either linear or branched.

  Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Specific examples of the alkenyl group include a vinyl group, a propenyl group, a 3-butenyl group, a 3-pentenyl group, and a 3-hexenyl group. Specific examples of the alkynyl group include ethynyl group, 2-propynyl group, and 2-butynyl group. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the cycloalkenyl group include a cyclopentenyl group, a cyclohexenyl group, and a cyclohexenyl group. Specific examples of the aryl group include a phenyl group, a naphthyl group, and an anthranyl group.

  The heterocyclic group, amino group, alkoxy group, alkylthio group, alkylcarbonyl group, arylcarbonyl group, alkylsulfonyl group, arylsulfonyl group, and hydrocarbon group may further have a substituent. Examples of the substituent include a hydroxy group, a carboxy group, an amino group, a cyano group, a nitro group, a sulfonamide group, a halogen atom, an acyl group, an acyloxy group, an alkoxycarbonyl group, and an oxo group.

Among the orthoquinone compounds represented by the above formula (1), any two or more groups of R ^{1 to} R ⁴ may be combined and each may be substituted with the carbon atom to which each is bonded. The compound which forms is preferable. The ring structure may be either an aromatic ring such as a benzene ring or an aliphatic ring. Examples of the substituent in the ring structure include a hydrocarbon group, a hydroxy group, a carboxy group, an amino group, a cyano group, a nitro group, a sulfonamide group, a halogen atom, an acyl group, an acyloxy group, an alkoxycarbonyl group, and an oxo group. Can be mentioned. The ring structure may contain a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom in at least a part of the ring structure.

The orthoquinone compound represented by the formula (1) is preferably a compound in which R ¹ and R ² and R ³ and R ⁴ are bonded to each other to form an aromatic ring, among which the following formula (2) is preferred. Orthoquinone compounds are more preferred.

In the formula (2), R ^{11 to} R ¹⁸ are each independently a hydrogen atom, a halogen atom, a heterocyclic group, an amino group, a nitro group, a formyl group, a cyano group, a hydroxy group, an alkoxy group, a thiol group, An alkylthio group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, or a hydrocarbon group; The heterocyclic group, amino group, alkoxy group, alkylthio group, alkylcarbonyl group, arylcarbonyl group, alkylsulfonyl group, arylsulfonyl group, and hydrocarbon group may be substituted. Any two or more groups of R ^{11 to} R ¹⁸ may be combined together to form an optionally substituted ring structure together with the carbon atom to which each is bonded.

Regarding the halogen atom, heterocyclic group, alkoxy group, alkylthio group, alkylcarbonyl group, arylcarbonyl group, alkylsulfonyl group, arylsulfonyl group and hydrocarbon group of R ^{11 to} R ¹⁸ , R in the above formula (1) It can be applied to the description of the ¹ to R ^4.

  Examples of the orthoquinone compound include orthoquinones having no substituent such as 9,10-phenanthrenequinone; halogenated orthoquinones such as dibromoorthoquinone, dichloroorthoquinone, diiodoorthoquinone, and difluoroorthoquinone. Of these, orthobenzoquinone or its halide, 9,10-phenanthrenequinone or its halide, pyrene-4,5-dione or its halide, or pyrene-4,5,9,10-tetraone or its halide. Preferably, 9,10-phenanthrequinone, 2,7-dibromo-9,10-phenanthrequinone, pyrene-4,5,9,10-tetraone, 2,7-dibromopyrene-4,5,9 , 10-tetraone, more preferably 9,10-phenanthrequinone and 2,7-dibromo-9,10-phenanthrequinone.

  The orthoquinone compound is also preferably an oligomer containing a structural unit derived from the compound represented by the formula (1). The structural unit derived from the compound represented by the formula (1) means a group constituted by removing at least one hydrogen atom from the compound represented by the formula (1). The position at which the hydrogen atom is removed is not particularly limited, and may be on an aromatic ring or on a substituent that the aromatic ring has.

  The oligomer in the present invention may be a homo-oligomer containing a structural unit derived from the compound represented by formula (1) or formula (2), or a hetero-oligomer containing a structural unit derived from these and other compounds. The bonds between the structural units may be ordinary chemical bonds such as single bonds, phenylene bonds, sulfide bonds, ether bonds, ester bonds, carbonate bonds, amide bonds, and imide bonds.

  The orthoquinone compound as the negative electrode active material may be contained in the negative electrode active material layer in the form of a salt formed with an alkali metal ion or alkaline earth metal ion as an anion having a reduced quinone moiety.

  The negative electrode active material layer may contain an orthoquinone compound alone or in combination of two or more.

(Positive electrode active material)
The positive electrode of the water-based secondary battery shown in the positive electrode sheet 13 of FIG. 1 described above includes, for example, a positive electrode active material layer containing a metallocene compound on a positive electrode current collector. The active material in the positive electrode of the water-based secondary battery includes a metallocene compound. Here, the metallocene compound is a sandwich-type bis (cyclopentadienyl) complex in which two cyclopentadienyl rings are arranged in parallel and a transition metal ion is inserted between them.

As a metallocene compound preferable as the positive electrode active material, an oligomer including a structural unit derived from a compound represented by the following formula (3) or a compound represented by the following formula (3) can be given. In formula (3), a structural formula of D _5d symmetry is shown, but D _5h symmetry may be used.

In the formula (3), R ^{21 to} R ³⁰ each independently represent a hydrogen atom, a halogen atom, a heterocyclic group, an amino group, a nitro group, a formyl group, a cyano group, a hydroxy group, an alkoxy group, a thiol group, An alkylthio group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, or a hydrocarbon group; The heterocyclic group, amino group, alkoxy group, alkylthio group, alkylcarbonyl group, arylcarbonyl group, alkylsulfonyl group, arylsulfonyl group, and hydrocarbon group may be substituted. M is a transition metal atom.

Examples of the halogen atom of R ^{21 to} R ³⁰ in the formula (3) include fluorine, chlorine, bromine, iodine and the like. For the heterocyclic group, alkoxy group, alkylthio group, alkylcarbonyl group, arylcarbonyl group, alkylsulfonyl group, arylsulfonyl group, and hydrocarbon group, the description of R ^{1 to} R ⁴ in the formula (1) is applied. it can.

  As M in the formula (3), Fe (iron), Ni (nickel), Sc (scandium), Ti (titanium), V (vanadium), Cr (chromium), Mn (manganese), Co (cobalt), Cu (copper), Zn (zinc), etc. are mentioned. From the viewpoint of improving the cycle characteristics of the aqueous secondary battery, Fe and Ni are preferable, and Fe is more preferable. That is, more preferred metallocene compounds are ferrocene compounds and oligoferrocene compounds in which M is Fe in the formula (3). Most preferred is ferrocene. Further, other molecules such as halides may be added to M.

  It is also preferable that the metallocene compound is an oligomer containing a structural unit derived from the compound represented by the formula (3). The structural unit derived from the compound represented by the formula (3) means a group constituted by removing at least one hydrogen atom from the compound represented by the formula (3). The position at which the hydrogen atom is removed is not particularly limited, and may be on a cyclopentadienyl ring or a substituent of the cyclopentadienyl ring. Specific examples of the structural unit derived from the compound represented by the formula (3) include the following structural units. In addition, other molecules such as halides may be added to M as in the formula (3).

（式中、Ｍは、遷移元素である。）

(In the formula, M is a transition element.)

  The metallocene compound that is a positive electrode active material may be contained in the positive electrode active material layer in the form of a salt formed with a halogen ion, a sulfate ion, a hydroxide ion, or the like as a cation in which the transition metal atom portion is oxidized.

  The positive electrode active material layer may contain one or more metallocene compounds in combination.

  Thus, the negative electrode includes a negative electrode active material layer including an orthoquinone compound, and the positive electrode includes a positive electrode active material layer including a metallocene compound. In addition, the negative electrode may include a conductive additive, a binder, and the like in addition to the above-described orthoquinone compound, which is the negative electrode active material, in the negative electrode active material layer. In the positive electrode active material layer, in addition to the metallocene compound that is the positive electrode active material described above, a conductive additive, a binder, and the like may be included.

  A carbon material can be used as the conductive additive contained in the positive electrode and the negative electrode. Examples of the carbon material include porous carbon materials such as activated carbon and activated carbon fibers. Among these, as the conductive auxiliary agent, it is more preferable that at least one of the positive electrode and the negative electrode contains activated carbon as the porous carbon material. In addition to the porous carbon material, the conductive additive may contain a carbon material having a nanostructure or a powder metal material having a nanostructure.

  As the binder contained in the positive electrode and the negative electrode, a material suitable for the application that does not decompose in the potential region to be used can be selected and used. For example, polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose, styrene butadiene rubber, polyacrylic acid, polyimide resin, polyamide resin, fluorine rubber, and the like.

  Each of the conductive additive and the binder contained in the positive electrode active material layer and the negative electrode active material layer may be used alone or in combination of two or more.

  In each of the electrode active material layers of the negative electrode active material layer and the positive electrode active material layer, the constituent ratios of the positive electrode or negative electrode electrode active material, the conductive additive, and the binder are 5 to 100% by mass, 0 to 0%, respectively. What is necessary is just to adjust suitably in the range of 90 mass% and 0-30 mass%. The conductive auxiliary agent and the binder may not be added. Moreover, the thickness of the negative electrode active material layer and the positive electrode active material layer is not particularly limited. The mass ratio of the positive electrode active material to the negative electrode active material is not particularly limited. For example, the positive electrode / negative electrode is preferably 0.5 to 10.0, and preferably 1.0 to 5.0. Is more preferable.

(Gelled aqueous electrolyte)
The gel-like aqueous electrolyte in the present invention is a gel obtained from an aqueous electrolyte, and can be obtained by adding a gelling agent to the aqueous electrolyte. A gel is an example of a pseudo-solid. In the present invention, gel is a type of dispersion, which is a colloid of a liquid dispersion medium such as sol, but has a high viscosity due to a dispersoid network and loses fluidity, and the entire system becomes solid. Say. The gel-like aqueous electrolyte of the present invention preferably has a loss coefficient (tan δ) measured by dynamic viscoelasticity measurement of 0.2 to 100 when the strain is 5.0%. A more preferable range is 0.2 to 3.0. By making the loss coefficient (tan δ) within the above numerical range, the safety of the water-based secondary battery of the present invention can be ensured, the decrease in battery capacity due to self-discharge can be reduced, and the cycle characteristics can be improved. Further improvement can be achieved. The loss coefficient (tan δ) can be calculated from the values obtained by obtaining the storage elastic modulus (G ′) and loss elastic modulus (G ″) corresponding to the angular frequency with a rheometer.

Aqueous Electrolytic Solution The aqueous electrolytic solution in the present invention contains water and at least one water-soluble salt. The water-soluble salt preferably contains at least one salt selected from the group consisting of salts of alkali metal elements and group 2 elements, and includes sodium salts, magnesium salts, calcium salts, lithium salts and beryllium salts. More preferably, it contains at least one salt selected from the group consisting of sodium salt and magnesium salt, more preferably sodium salt.

  The kind of anion contained in the water-soluble salt is not particularly limited. Examples of anions include halide ions, sulfate ions, nitrate ions, phosphate ions, and the like. Specifically, the halide ions are chloride ions, bromide ions, iodide ions and the like.

  The water-soluble salt is preferably a neutral salt at 25 ° C., among which at least one neutral sodium salt selected from the group consisting of sodium chloride, sodium bromide, sodium iodide, sodium sulfate, sodium nitrate and the like. More preferably, at least one neutral magnesium salt selected from the group consisting of magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, magnesium nitrate, lithium chloride, and the like, and sodium chloride, sodium sulfate, and magnesium chloride are further included. Sodium chloride and sodium sulfate are preferable.

  The concentration of the water-soluble salt in the aqueous electrolyte is appropriately selected according to the type of the water-soluble salt. The concentration of the water-soluble salt in the aqueous electrolyte varies depending on the temperature and solute. For example, when the water-soluble electrolyte is 20 ° C. and the water-soluble salt is sodium chloride, 0.1 mol / L to 6 It is preferably in the range of 1 mol / L. If the aqueous solution salt is magnesium chloride, it is preferably in the range of 0.1 mol / L to 5.7 mol / L. The concentration of the water-soluble salt in the aqueous electrolytic solution may be equal to or lower than the saturation solubility, and a higher concentration is more preferable.

  The aqueous electrolytic solution may contain a water-soluble organic solvent. Examples of the organic solvent include acetonitrile and acetone.

  When the aqueous electrolyte contains an organic solvent, the content is 50% by mass or less with respect to water, and preferably 10% by mass or less.

  The aqueous electrolyte may contain various additives as required. Examples of the additive include sodium sulfite.

Gelling agent The gelling agent in the present invention is not particularly limited as long as it is a chemical substance that gels and solidifies a liquid. In view of improving the safety of the water-based secondary battery of the present invention, reducing the battery capacity, and further improving the cycle characteristics, the gelling agent used in the present invention is a water-soluble gel. An agent is preferred.

  Examples of the water-soluble gelling agent include gelling agents usually used as food additives, thickeners, stabilizers, thickening polysaccharides such as pastes, water-soluble polymers, and the like. Examples of thickening polysaccharides include sodium carboxymethylcellulose, sodium alginate, carrageenan, xanthan gum, guar gum, agar, pectin, locust bean gum, tamarind seed gum, gum arabic, pullulan, hyaluronic acid, chitosan, soy polysaccharide, etc. It is done. Examples of the water-soluble polymer include polyvinyl alcohol, polyethylene oxide, polyacrylonitrile, polyacrylic acid, polyvinylamine, polyvinylacetamide, polyoxazine, polyvinylpyrrolidone, polylysine, and gelatin. Of these, sodium carboxymethylcellulose and sodium alginate are preferred. In addition, these gelling agents may be used individually by 1 type, and may be used combining several types.

  The gelled aqueous electrolyte of the present invention is added to the aqueous electrolyte under the condition of 15 to 90 ° C., 0.1 to 20% by mass of the gelling agent, crushed with a spatula or the like, stirred with a homomixer or the like, It is obtained by leaving still for 0.1 to 10 hours in a predetermined container. As the concentration of the gelling agent, the solubility varies depending on the temperature and solute. From the viewpoint of reducing the battery capacity reduction of the aqueous secondary battery of the present invention and further improving the cycle characteristics, the aqueous electrolyte is saturated. A lower concentration and a higher concentration are preferred. The concentration of the gelling agent is, for example, 1.0 to 7 when the gelling agent is carboxymethylcellulose when the gelling agent is added to an aqueous electrolyte of a 1 mol / L sodium chloride aqueous solution at room temperature. About 0.5% by mass is preferable, and when the gelling agent is sodium alginate, about 0.5 to 2.5% by mass is preferable.

  In the aqueous secondary battery of the present invention, by using a gelled aqueous electrolyte, the diffusion of ions in the electrolyte and the ionic conductivity are suppressed by the interaction between the ions dissolved in the electrolyte and the gelling agent. The Thereby, it is considered that a decrease in battery capacity due to self-discharge can be suppressed and cycle characteristics can be improved. The diffusion of ions and the decrease in ionic conductivity of the gel-like aqueous electrolyte are shown by the results of the rate test described later. Moreover, since the electrolyte state is close to the saturation solubility by making the electrolyte into a gel state, suppression of elution of the active material of the positive electrode and the negative electrode and a decrease in dissolved oxygen may be considered.

(Separator)
The aqueous secondary battery may include a separator. The separator is disposed so as to separate the positive electrode and the negative electrode, and is required to pass ions and prevent a short circuit between the positive and negative electrodes. The separator is not particularly limited, and a conventionally known separator can be used. For example, a polyolefin fiber nonwoven fabric, a microporous membrane made of polyolefin, a glass filter, a ceramic porous material, or the like can be used.

[Method for producing water-based secondary battery]
The aqueous secondary battery of the present invention is manufactured by enclosing a negative electrode and a positive electrode, and a gelled aqueous electrolyte in a housing case such as the cylindrical case 22 of FIG. A specific assembly procedure will be described below. In addition, the specific manufacturing method of the water-system secondary battery of this invention is demonstrated in detail in an Example.

  The positive electrode and the negative electrode are cut into a shape such as a quadrilateral, and the current collector is spot welded using a platinum mesh or the like with platinum attached to the end of the surface on which the electrode is not formed, as a positive electrode or a negative electrode terminal. Can be attached. A separator made of the electrode and the regenerated cellulose nonwoven fabric is attached to a laminate cell or the like. A gelled aqueous electrolyte is placed between the positive electrode and the negative electrode, and the laminate cell can be sealed using a vacuum sealer device or the like.

  In addition to the structure manufactured by sealing with the laminate cell described above, it may be manufactured with a structure using a glass sample bottle cell or the like. The manufacturing method in the structure using a glass sample bottle cell etc. is as follows, for example. First, the positive electrode and the negative electrode are spot-welded, for example, by cutting into a quadrilateral shape and using a platinum mesh or the like with platinum attached to the end of the surface on which the electrode is not formed as a positive electrode or a negative electrode terminal. Attach with. Then, the electrode is attached to a glass sample bottle cell or the like, a gel-like aqueous electrolyte is placed between the positive electrode and the negative electrode, and the sample bottle cell can be sealed with a lid.

  Next, specific embodiments of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

<Production of water-based secondary battery>
(Preparation of positive electrode)
A positive electrode active material was supported on activated carbon as a conductive aid. In a mortar, the activated carbon supporting the positive electrode active material and polytetrafluoroethylene (PTFE) as a binder were mixed and kneaded. A positive electrode was produced by providing a positive electrode active material layer formed by rolling the mixture on a current collector.

(Preparation of negative electrode)
A negative electrode active material was supported on activated carbon as a conductive aid. In a mortar, the activated carbon supporting the negative electrode active material and polytetrafluoroethylene (PTFE) as a binder were mixed and kneaded. A negative electrode was produced by providing a negative electrode active material layer formed by rolling the mixture on a current collector.

  Examples of a method for supporting each electrode active material on the conductive assistant in each electrode include a method of uniformly attaching each electrode active material to the conductive assistant via a liquid phase. The rolling is performed by roll rolling using a roller press or the like. By this roll rolling, each electrode active material layer of the positive electrode and the negative electrode can be made into an electrode having a flat surface that is further compressed to a predetermined thickness and smoothed.

(Production of gelled aqueous electrolyte)
30 ml of the aqueous electrolytic solution described in Table 1 below was put in a snap cup, and each gelling agent was added in the amount shown in Table 1 and crushed with a spatula. The mixture was stirred at room temperature for 5 minutes using a homomixer (10,000 rpm) and allowed to stand at room temperature to obtain the following aqueous electrolytes [1] to [10]. [1] and [2] are only aqueous electrolytes for use in comparative examples, and [3] to [10] are gel aqueous electrolytes.

(Dynamic viscoelasticity measurement)
The dynamic viscoelasticity measurement of each obtained gel-like aqueous electrolyte was performed with a rheometer MCR301 (manufactured by Anton Paar), and the storage elastic modulus (G ′) and loss elastic modulus (G ″) corresponding to the angular frequency were calculated. The loss coefficient (tan δ) at a strain of 5.0% was calculated from the obtained value. PP25-SN978 was used as the measurement jig, the measurement distance was 1.0 mm, and the measurement temperature was 25 ° C. The formula for calculating tan δ is as follows.

tan δ = G ″ / G ′

The results are shown in Table 1 above.

(Battery assembly method)
The obtained positive electrode and negative electrode were cut into a quadrilateral shape, and the current collector was spot welded using a platinum mesh with a platinum mesh attached to the end of the surface where no electrode was formed, as a positive electrode or a negative electrode terminal. Attached. And the said electrode was attached to the glass sample bottle cell, and the gelatinous aqueous electrolyte was put between the positive electrode and the negative electrode. The sample bottle cell was sealed with a lid.

(Rate test)
Using each of the aqueous electrolytes described in Table 1 above, water-based secondary batteries of Comparative Examples 1 and 2 and Examples 1 to 8 were produced. Table 2 below shows the types and masses of the positive electrode active material, the negative electrode active material, the conductive auxiliary, the binder, and the electrolyte used.

正極活物質：フェロセン
負極活物質：２，７-ジブロモ−９，１０−フェナントレンキノン
導電助剤：活性炭
結着材：ポリテトラフルオロエチレン（ＰＴＦＥ）

Positive electrode active material: Ferrocene negative electrode active material: 2,7-dibromo-9,10-phenanthrenequinone conductive auxiliary agent: activated carbon binder: polytetrafluoroethylene (PTFE)

  The aqueous secondary batteries of Comparative Examples 1-2 and Examples 1-8 were subjected to a charge / discharge test. The conditions of the charge / discharge test were set to a voltage range of 0 to 1.1 V with current values of 1C, 2C, 3C, 5C, 10C, 15C, and 20C assuming that the capacity at 0.5C was a theoretical capacity. Table 3 shows the capacity retention rate (%) at each rate for the results obtained under each charge / discharge condition.

(Charge / discharge cycle characteristics evaluation)
Using each aqueous electrolyte described in Table 1 above, water-based secondary batteries of Comparative Examples 3 and 4 and Examples 9 to 16 were produced. Table 4 below shows the positive electrode active material, the negative electrode active material, the conductive additive, the type and mass of the binder, and the type of the electrolyte.

正極活物質：フェロセン
負極活物質：２，７-ジブロモ−９，１０−フェナントレンキノン
導電助剤：活性炭
結着材：ポリテトラフルオロエチレン（ＰＴＦＥ）

Positive electrode active material: Ferrocene negative electrode active material: 2,7-dibromo-9,10-phenanthrenequinone conductive auxiliary agent: activated carbon binder: polytetrafluoroethylene (PTFE)

  The aqueous secondary batteries of Comparative Examples 3 to 4 and Examples 9 to 16 were subjected to a charge / discharge test. The conditions for the charge / discharge test were a current value at a 2C rate relative to the theoretical capacity of the battery, and a voltage range of 0 to 1.1V. The charge / discharge test was started from the charge, and the repetition capacity maintenance rate was expressed as a percentage of the discharge capacity at the 25th, 50th, 100th, and 200th cycles with respect to the discharge capacity of the cycle where the discharge capacity was maximized. . The results are shown in Table 5. The cycle showing the maximum discharge capacity was described as the maximum value cycle.

  As shown in Table 5, it was confirmed that the aqueous secondary batteries of Examples 9 to 16 were superior in the capacity retention rate compared to the aqueous secondary batteries of Comparative Examples 3 and 4.

(Self-discharge evaluation)
Using the aqueous electrolytic solution described in Table 1, water-based secondary batteries of Comparative Examples 5 and 6 and Examples 17 to 24 were produced. Table 6 below shows the types and masses of the positive electrode active material, the negative electrode active material, the conductive auxiliary, the binder, and the electrolyte used.

正極活物質：フェロセン
負極活物質：２，７-ジブロモ−９，１０−フェナントレンキノン
導電助剤：活性炭
結着材：ポリテトラフルオロエチレン（ＰＴＦＥ）

Positive electrode active material: Ferrocene negative electrode active material: 2,7-dibromo-9,10-phenanthrenequinone conductive auxiliary agent: activated carbon binder: polytetrafluoroethylene (PTFE)

  The aqueous secondary batteries of Comparative Examples 5 to 6 and Examples 17 to 24 were charged and discharged for 19 cycles at 2C, and then charged at the 20th cycle, and the change in voltage over time was monitored. The voltage at the start of 1.1V was taken as 100%, and the voltage after 10 hours and 24 hours was shown as a percentage of the voltage at the start (Table 7).

  As shown in Table 7, the battery capacity retention after 10 hours and 24 hours of Examples 17 to 24 was higher than that of Comparative Examples 5 and 6. It was confirmed that the water-based secondary batteries of Examples 17 to 24 had little decrease in battery capacity due to self-discharge.

  The aqueous secondary battery of the present invention is safe even if it is damaged in use by using a gel-like aqueous electrolyte. In addition, the secondary battery of the present invention can reduce the decrease in battery capacity due to self-discharge by gelling the aqueous electrolyte, and can further improve the cycle characteristics. Further, by using a metallocene compound for the positive electrode and an orthoquinone compound for the negative electrode as active materials, a secondary battery with higher output and higher charge / discharge cycle characteristics can be provided. Therefore, it is suitably used for the power source or uninterruptible power supply of various portable electronic devices and transportation devices.

DESCRIPTION OF SYMBOLS 10 Water-system secondary battery 11 Positive electrode collector 12 Positive electrode active material layer 13 Positive electrode sheet 14 Negative electrode collector 17 Negative electrode active material layer 18 Negative electrode sheet 19 Separator 20 Gel-like aqueous electrolyte 22 Cylindrical case 24 Positive electrode terminal 26 Negative electrode terminal

Claims (9)

  An aqueous secondary battery comprising: a positive electrode including a metallocene compound as an active material; a negative electrode including an orthoquinone compound as an active material; and a gelled aqueous electrolyte.   The aqueous secondary battery according to claim 1, wherein the gel-like aqueous electrolyte is obtained by adding a gelling agent to an aqueous electrolytic solution.   The aqueous secondary battery according to claim 1 or 2, wherein the gelling agent is a water-soluble gelling agent.   The aqueous secondary battery according to claim 3, wherein the gelling agent is at least one compound selected from the group consisting of sodium carboxymethylcellulose and sodium alginate.   The water-based secondary battery according to any one of claims 1 to 4, wherein at least one of the positive electrode and the negative electrode contains a conductive assistant of a porous carbon material.   6. The aqueous secondary battery according to claim 1, wherein the electrolyte contains at least one salt selected from the group consisting of a salt of an alkali metal element and a salt of a Group 2 element.   The aqueous secondary battery according to claim 6, wherein the electrolyte contains a sodium salt.   The aqueous secondary battery according to claim 1, wherein the metallocene compound is ferrocene.   The said orthoquinone compound is at least 1 sort (s) of compound selected from 9,10-phenanthrene quinone, dibromo ortho quinone, dichloro ortho quinone, difluoro ortho quinone, and diiodo ortho quinone. The aqueous secondary battery as described.

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