JP2007227136A - Power storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power storage device of high reliability, in which the capacity reduction of the charged power storage device can be suppressed and in which short circuit between positive and negative electrodes is prevented. <P>SOLUTION: This is the power storage device including the positive electrode, containing a positive electrode active material, the negative electrode containing a negative electrode active material, and an electrolyte, at least either of the positive electrode active material and the negative electrode active material contains an organic compound, having a π-electron conjugate cloud or the organic compound having a radical, and it has an inorganic porous film having a through hole between the positive electrode and the negative electrode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to high reliability of an electricity storage device.

  In recent years, with the widespread use of hybrid vehicles that can be driven by both gasoline and electricity, and uninterruptible power supplies, mobile communication devices, portable electronic devices, and other devices that require power sources, the demand for such power sources has increased. It is very big.

  For this reason, there is a strong demand for higher performance of lithium-ion batteries and electric double layer capacitors as power sources, and development of higher performance of these is energetically advanced.

  For example, in order to realize an electricity storage device with high output and high energy density, studies have been made on using organic compounds as electrode materials. The compound and the reaction mechanism thereof have been clarified by the present inventors (see, for example, Patent Document 1).

On the other hand, as one of the developments for improving the performance of lithium-ion batteries, efforts for higher reliability can be mentioned. For example, in order to prevent a short circuit between the positive electrode and the negative electrode, a technique of providing a short circuit prevention layer on the surface of the positive electrode plate or the negative electrode plate is disclosed (for example, see Patent Documents 2 and 3).
JP 2004-111374 A JP 2005-327680 A JP 2005-285605 A

  In an electricity storage device using an organic compound having a π-electron conjugated cloud or an organic compound having a radical as an electrode active material, there is a problem that when the charge / discharge reaction is repeated, the discharge electric capacity of the charged electricity storage device decreases.

  This is because the organic compound that is the active material dissolves to the extent that it cannot be ignored from the inside of the electrode due to charge / discharge depending on the combination with the solvent used in the electrolyte, and the eluted active material freely passes between the positive and negative electrodes. This is due to being able to move. Since the active material eluted in the electrolyte can freely move in the electrolyte, it is reduced on the negative electrode surface and then oxidized on the positive electrode surface. That is, an active material discharge reaction is caused in both the positive electrode and the negative electrode. In other words, it can be said that the eluted active material causes a chemical internal short circuit between the positive and negative electrodes. As a result, the storage capacity of the electricity storage device is reduced when the electricity storage device is used without being charged.

  In addition, the active material dissolved in the electrolyte cannot react with the battery again in the electrode, leading to a reduction in the capacity of the electricity storage device corresponding to the amount of elution.

In order to solve the conventional problem, an electricity storage device of the present invention is an electricity storage device including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte.
At least one of the positive electrode active material and the negative electrode active material contains an organic compound having a π electron conjugated cloud or an organic compound having a radical,
An inorganic porous film having a through hole is provided between the positive electrode and the negative electrode.

  By providing the inorganic porous film having a through hole between the positive electrode and the negative electrode, it is possible to suppress the eluted active material from freely moving between the positive and negative electrodes. Thereby, the capacity | capacitance fall of the charged electrical storage device can be suppressed.

  Furthermore, since the inorganic porous film is excellent in heat resistance and mechanical strength, providing this between the positive and negative electrodes can provide a highly reliable power storage device that prevents a short circuit between the positive and negative electrodes.

  In the electricity storage device of the present invention, it is preferable that an organic compound having an ionic functional group is modified on the surface of the through hole of the inorganic porous membrane layer having the through hole. This is because the ionic functional group causes Coulomb interaction with the eluted charged active material, and can further prevent the eluted active material from freely moving between the positive and negative electrodes.

  According to the electricity storage device of the present invention, high reliability is achieved in an electricity storage device having a high output and high energy density using an electrode containing an organic compound having a π-electron conjugated cloud or an organic compound having a radical as an active material. be able to.

(Embodiment 1)
The best mode for carrying out the present invention will be described below with reference to the drawings.

  The electricity storage device in Embodiment 1 is an electricity storage device including a positive electrode including an organic compound having a π-electron conjugated cloud or an organic compound having a radical as a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte. Thus, the electricity storage device has an inorganic porous film layer having a through hole between the positive electrode and the negative electrode.

  FIG. 1 is a schematic cross-sectional view schematically showing an electricity storage device according to Embodiment 1 of the present invention. In FIG. 1, a positive electrode 13 is an electrode containing an organic compound having a π-electron conjugated cloud or a radical as an active material, and an inorganic porous film layer 14 is disposed on the surface of the positive electrode 13. The separator 15 is disposed between the positive electrode 13 and the negative electrode 18. When an electrolyte solution is injected and impregnated into the separator 15, it also acts as an electrolyte. On top of that, the negative electrode 18 is disposed so as to face the positive electrode 13, and these sets are clamped using a gasket 19 so as to be sandwiched between the case 11 and the sealing plate 16, and sealed to form an electricity storage device. Is done. Further, a positive electrode current collector 12 is disposed between the positive electrode 13 and the case 11 as necessary, and a negative electrode current collector 17 is disposed between the negative electrode 18 and the sealing plate 18 as necessary. ing.

  The main components in the electricity storage device in Embodiment 1 will be described in detail below.

  The positive electrode 13 contains an organic compound (not shown) having a π-electron conjugated cloud or radical as an active material.

  Examples of the organic compound having a π electron conjugated cloud include organic compounds having structures represented by the following general formula (1) and general formula (2).

  General formula (1):

(In the formula, X is a sulfur atom or an oxygen atom, R ^{1 to} R ⁴ are each an independent chain aliphatic group, cyclic aliphatic group, hydrogen atom, hydroxyl group, cyano group, amino group, nitro group or A nitroso group, wherein R ⁵ and R ⁶ are a hydrogen atom, a chain aliphatic group, and a cyclic aliphatic group, respectively, and the aliphatic group includes an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, (Including at least one selected from the group consisting of boron atoms and halogen atoms)
General formula (2):

(Wherein X is a nitrogen atom, R ^{1 to} R ⁴ are each an independent chain aliphatic group, cyclic aliphatic group, hydrogen atom, hydroxyl group, cyano group, amino group, nitro group or nitroso group. , R ⁵ , and R ⁶ are each a hydrogen atom, a chain aliphatic group, or a cyclic aliphatic group, and the aliphatic group includes an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom, and a halogen atom. (Including at least one selected from the group consisting of atoms.)
Examples of the organic compound having another π-electron conjugated cloud of the present invention include an organic compound having a structure represented by the following general formula (3).

  General formula (3):

Wherein X ^{1 to} X ⁴ are each independently a sulfur atom, oxygen atom, selenium atom, tellurium atom, and R ^{1 to} R ² are each an independent chain aliphatic group or cyclic aliphatic group, The aliphatic group includes 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.)
Specific examples of the compound represented by the general formula (1) include a compound represented by the general formula (4) and a compound represented by the formula (5).

  General formula (4):

(Wherein R ^{1 to} R ⁴ and R ^{7 to} R ¹⁰ are each a chain aliphatic group, a cyclic aliphatic group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group; The aliphatic group contains at least one selected from the group consisting of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom and halogen atom.
Formula (5):

  The compound of the formula (5) has a small molecular weight among the compound group of the general formula (1), and a high reaction rate is expected.

In the group of the general formula (4), the energy level at which electrons are extracted from the two 5-membered rings approaches due to the presence of the two benzene rings located in the two 5-membered rings, and the reaction is as if it were a one-electron reaction. proceed. Therefore reaction rate R ^5, R ⁶ in the general formula (1) is advanced as compared with the case without the benzene ring. As typical examples of the compound of the general formula (4), compounds represented by the formulas (6) to (9) are preferable compounds.

  Formula (6):

  Formula (7):

  Formula (8):

  Formula (9):

  Specific examples of the compound represented by the general formula (3) described above include compounds represented by the general formulas (10) to (13).

  General formula (10):

(In the formula, X ^{1 to} X ⁴ are each independently a sulfur atom, oxygen atom, selenium atom, tellurium atom, R ^{3 to} R ⁶ are each an independent chain aliphatic group, cyclic aliphatic group, hydrogen atom, A hydroxyl group, a cyano group, an amino group, a nitro group or a nitroso group, and the aliphatic group is at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. Including seeds.)
General formula (11):

(Wherein X ^{1 to} X ⁴ are each independently a sulfur atom, oxygen atom, selenium atom, tellurium atom, Y, Z are independently selected from the group consisting of a sulfur atom, oxygen atom, selenium atom, tellurium atom, and methylene group. (Including at least one selected)
Formula (12):

(Wherein X ^{1 to} X ⁴ are each independently a sulfur atom, oxygen atom, selenium atom, tellurium atom, R ⁹ and R ¹⁰ are each an independent chain aliphatic group, cyclic aliphatic group, hydrogen atom, A hydroxyl group, a cyano group, an amino group, a nitro group or a nitroso group, and the aliphatic group is at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. Including seeds.)
General formula (13):

(Wherein, including X ¹ to X ⁴ each independently represents a sulfur atom, an oxygen atom, a selenium atom, at least one selected from the group consisting of tellurium atoms.)
Moreover, as an organic compound which has a radical, the organic compound which has at least any one of a nitroxy radical and an oxygen radical in a molecule | numerator is mentioned. Specifically, nitroxy radicals represented by 2,2,6,6-tetramethylpiperidine-1-oxyl, 2,2,5,5-tetramethyl-3-imidazolium-1-loxy, quinone And quinones such as benzoquinone.

  In the embodiment in which the positive electrode active material composed of the various organic compounds described above is used for the positive electrode 13, carbon materials such as carbon black, graphite, and acetylene black, polyaniline, polypyrrole, polythiophene, and the like are used for the purpose of imparting electronic conductivity to the organic compound. A conductive polymer can be used by mixing with a compound.

  Further, the positive electrode 13 may be mixed with a solid electrolyte made of polyethylene oxide or the like as an ion conductive auxiliary agent, or a gel electrolyte made of polymethyl methacrylate or the like.

  Furthermore, for the purpose of binding organic compounds, the positive electrode 13 is mixed with a binder such as polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-polytetrafluoroethylene, polyethylene, polyimide, or polyacrylic acid. You may do it.

The electrode material is preferably applied to the positive electrode current collector 12 such as a metal foil, a metal mesh, or a resin film containing a conductive filler, as in a general battery.

  The electrolyte (not shown) is a solution containing an electrolyte compound, and the electrolyte solution is a polymer electrolyte containing polyacrylonitrile, an acrylate monomer or a methacrylate monomer, a polymer electrolyte gelled with a copolymer of ethylene and acrylonitrile, or a solid An electrolyte is applied. When the electrolyte is a solution, the separator 15 is preferably impregnated with the electrolyte solution.

  As electrolyte, what can be used for a lithium ion battery and a non-aqueous electric double layer capacitor can be used. Specifically, salts formed by combinations of cations and anions listed below can be used. As the cation species, alkali metal cations such as lithium, sodium and potassium, alkaline earth metal cations such as magnesium, quaternary ammonium cations such as tetraethylammonium and 1,3-ethylmethylimidazolium can be used. Anionic species include halide anions, perchlorate anions and trifluoromethanesulfonate anions, tetraborofluoride anions, trifluorophosphoric hexafluoride anions, trifluoromethanesulfonate anions, bis (trifluoromethanesulfonyl) imide anions, bis (per Fluoroethylsulfonyl) imide anion, and the like. These can be used alone or in combination.

  When the electrolyte itself is in the form of a solution, it can be used alone without necessarily mixing it with a solvent. When the electrolyte itself is solid, it is necessary to use it by dissolving it in the following solvent.

  As the solvent for forming the electrolyte solution, those that can be used for lithium ion batteries and non-aqueous electric double layer capacitors can be used. Specifically, nonaqueous solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyl lactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, and acetonitrile are preferable. These can be used alone or in combination.

Other solid electrolytes include Li ₂ S—SiS ₂ , Li ₂ S—B ₂ S ₅ , Li ₂ S—P ₂ S ₅ —GeS ₂ , sodium / alumina (Al ₂ O ₃ ) amorphous or low phase transition temperature ( Tg) polyether, amorphous vinylidene fluoride-6-fluoropropylene copolymer, heterogeneous polymer blend polyethylene oxide and the like. In addition, all need to contain the cation coordinated to the said compound at the time of charge.

  Next, the negative electrode 18 will be described. In the first embodiment of the present invention, the negative electrode 18 includes, as a negative electrode active material, graphite, amorphous carbon material, lithium metal, lithium-containing composite nitride, lithium-containing titanium oxide, tin (Sn), and silicon (Si). , Silicon oxide (SiOx), activated carbon, carbon compounds such as carbon nanotubes, or composites with other metals can be used. Or the organic compound quoted by the positive electrode material of this invention can also be used as a negative electrode active material material, if a reaction potential is relatively low.

  When activated carbon, which is the negative electrode active material of the present invention, is used for the negative electrode 18, for the purpose of imparting electronic conductivity, the negative electrode 18 is made of a carbon material such as carbon black, graphite, acetylene black, and conductive materials such as polyaniline, polypyrrole, and polythiophene. The functional polymer can be used by mixing with a compound.

  The negative electrode 18 may be mixed with a solid electrolyte made of polyethylene oxide or the like, or a gel electrolyte made of polymethyl methacrylate or the like as an ion conductive auxiliary agent.

  Further, for the purpose of binding the negative electrode active material to the electrode, the negative electrode 18 is coated with polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-polytetrafluoroethylene, polytetrafluoroethylene, polyethylene, polyimide. , Binders such as polyacrylic acid, carboxymethylcellulose, acrylonitrile, butadiene rubber, styrene butadiene rubber may be mixed.

The electrode material is preferably applied to the negative electrode current collector 17 such as a metal foil, a metal mesh, or a resin film containing a conductive filler, as in a general battery.

  As the inorganic porous film 14 having a through hole in the first embodiment, any of metal oxide, glass, ceramics, or a mixture thereof can be used. Specifically, silica, alumina, titania, zirconia and the like are preferably used from the viewpoint of thermal stability and chemical stability. As those to be mixed with these, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-polytetrafluoroethylene, polytetrafluoroethylene, polyethylene, polyimide, polyacrylic acid, carboxymethylcellulose, acrylonitrile, Binders such as butadiene rubber and styrene butadiene rubber can be used.

  As shown in FIG. 1, the inorganic porous film 14 having through holes is arranged between the positive electrode 13 and the separator 15 (electrolyte) or the separator 15 (electrolyte) using an inorganic porous film processed into a film shape. And the negative electrode 18. Alternatively, the inorganic porous film 14 may be directly synthesized on the surface of the positive electrode 13, the separator 15, or the negative electrode 18. When the electrolyte is solid, the inorganic porous film 14 may be directly synthesized on the surface of the solid electrolyte.

  Specifically, it is obtained by dispersing fine particles of silica, alumina, titania, zirconia or the like in water or an organic solvent, and applying and drying the obtained slurry on the surface of the positive electrode 13, the separator 15, or the negative electrode 18. Alternatively, the inorganic porous film 14 may be formed on the surface of the positive electrode 13, the separator 15, or the negative electrode 18 by a sol-gel method. Specifically, a gel obtained by dissolving a metal alkoxide such as tetraethoxysilane or titanium tetraisopropoxide in an aqueous solvent or an organic solvent, and hydrolyzing and polycondensing the positive electrode 13 and the separator 15. Alternatively, it can be obtained by applying and drying on the surface of the negative electrode 18.

  Next, the effect of the electrical storage device which has the inorganic porous film 14 which has a through-hole between the positive electrode 13 and the negative electrode 18 of this invention is demonstrated.

  By providing the inorganic porous membrane 14 having a through hole between the positive and negative electrodes, it is possible to suppress the eluted active material from freely moving between the positive and negative electrodes. Thereby, the capacity | capacitance fall by the internal short circuit of the charged electrical storage device can be suppressed.

  For example, when tetrathiafulvalene as an organic compound having a π-electron conjugated cloud is used as the positive electrode active material, the positive electrode active material is positively charged during the charge and is eluted into the electrolyte. The positive electrode active material having a positive charge forms a structure solvated by an electrolyte anion or a solvent. Since the structure including these positive electrode active materials freely moves in the electrolyte and the capacity is reduced by reciprocating between the surface of the positive electrode 13 and the surface of the negative electrode 18, the movement of these active material structures between the positive and negative electrodes is caused. It is effective to dispose the inorganic porous film 14 to be suppressed.

  The charged positive electrode active material can have a cluster structure due to the interaction between the positive electrode active materials, the coordination of anions, and the solvation. Therefore, it is effective that the pore diameter of the through hole of the inorganic porous film 14 to be arranged is small, and specifically, 50 nm or less is preferable. On the other hand, since the electrolyte salt is smaller than the charged active material cluster, it is considered that the migration of the electrolyte ion due to the arrangement of the inorganic porous membrane 14 is not greatly suppressed.

  Moreover, since the inorganic porous film 14 is excellent in heat resistance and mechanical strength, providing this between the positive and negative electrodes can provide a highly reliable power storage device that prevents a short circuit between the positive and negative electrodes.

(Embodiment 2)
Hereinafter, a second embodiment for carrying out the present invention will be described with reference to the drawings.

  The electricity storage device in the second embodiment is exactly the same as in the first embodiment except that the surface of the through-hole of the inorganic porous film 14 having the through-hole to be used is modified with an organic compound having an ionic functional group. Since it is a structure, the same code | symbol is used about the same component and description is abbreviate | omitted.

  FIG. 2 is a schematic cross-sectional view of the inorganic porous film 14 having through holes used in the electricity storage device of the present invention, and FIG. 3 is a schematic view of the inside of the through holes of the inorganic porous film 14.

  In FIG. 2, a large number of through holes 21 are opened in the inorganic porous film 14. As shown in FIG. 3, the inside of the through hole 21 is modified with an organic compound 23 having a sulfonic acid group 24 that is an ionic functional group on the surface 22 of the through hole 21.

For example, when tetrathiafulvalene is used as the organic compound having a π-electron conjugated cloud as the positive electrode active material, the positive electrode active material is positively charged during the charge and is eluted into the electrolyte. The positive electrode active material having a positive charge forms a structure solvated by an electrolyte anion or a solvent. Since these active material structures have a positive charge as a whole, they cause a Coulomb interaction with the ionic functional group inside the through hole 21 in the inorganic porous film 14, and the inside of the inorganic porous film 14. It is thought that free motility is suppressed. Specifically, when the ionic functional group is a sulfonic acid group, an anionic functional group (SO ₃ ⁻ ) having a negative charge is obtained by dissociating protons in a state where the inorganic porous membrane 14 is impregnated with an electrolyte. Become. Due to the negative charge of the anionic functional group and the Coulomb attractive force due to the positive charge of the eluted positive electrode active material, the positive electrode active material inside the inorganic porous film 14 is attracted to the surface 22 of the through-hole, and free mobility. Will be disturbed. By this action, the movement of the eluted positive electrode active material between the positive and negative electrodes can be suppressed, thereby suppressing the capacity reduction due to the internal short circuit of the charged power storage device.

  A functional group having a positive charge can be used as the ionic functional group of the organic compound that modifies the surface 22 of the through hole. A functional group having a positive charge is a functional group that releases an anion and exhibits anionicity. Besides a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, a hydroxyl group, an ether bond, or a cation salt thereof. Is mentioned.

  In the second embodiment, the ionic functional group of the organic compound that modifies the surface 22 of the through hole has been described as a functional group having a positive charge. However, the functional group that can be used is not limited to this. Moreover, the movement between the positive electrode and the negative electrode of the positive electrode active material that has been eluted even with a functional group having a negative charge which is a functional group having a reverse charge can be suppressed.

  The functional group having a negative charge is a functional group that accepts a cation and exhibits a cationic property, and examples thereof include an amine group, an imine group, an ammonium group, and an anion salt thereof. For example, when an organic compound having a quaternary ammonium group, which is an ammonium group, is modified on the surface 22 of the through hole, the quaternary ammonium group accepts a cation while the inorganic porous membrane 14 is impregnated with an electrolytic solution. And a cationic functional group. Due to the positive charge of the cationic functional group and the Coulomb repulsion caused by the positive charge of the eluted positive electrode active material, the penetration of the positive electrode active material into the inorganic porous film 14 is suppressed, and the positive electrode active material thus eluted is positively charged. The free movement between the negative electrodes can be suppressed, and thereby the capacity reduction due to the internal short circuit of the charged power storage device can be suppressed.

  Modification of the organic compound 23 having the ionic functional group 24 on the surface 22 of the through hole of the inorganic porous film 14 can be performed by a coupling reaction represented by a silane coupling reaction. Modification can be made by polycondensation between a hydroxyl group present on the surface 22 of the through hole and a coupling agent comprising a metal alkoxide such as silane or titanium. The coupling agent having an ionic functional group may be used to modify the surface 22 of the through-hole, or after modifying the organic compound on the surface 22 of the through-hole, the ionic functional group is contained inside the organic compound by a chemical reaction. 24 may be introduced.

  In the second embodiment, the example in which the surface 22 of the through hole is modified with the organic compound 223 having one ionic functional group 24 in the molecule is shown. However, the surface has 22 functional groups in the molecule. Alternatively, after modifying the organic compound on the surface 22 of the through hole, the organic compound having a functional group may be polymerized by a chemical reaction to introduce the organic compound having a plurality of functional groups. The organic compound introduced into the surface 22 of the through hole may be a polymer.

  Hereinafter, the electricity storage device of the present invention will be described in detail together with examples.

Example 1
In Example 1, an alumina porous membrane (Whatman, Anopore (trade name)) having a thickness of 60 μm and a pore diameter of 20 nm was used as the inorganic porous membrane layer having through-holes used in the electricity storage device.

(Example 2)
In Example 2, the same alumina porous membrane as in Example 1 is used as the inorganic porous membrane layer having a through-hole used for the electricity storage device, and the surface of the through-hole has a sulfonic acid group that is a functional group having a positive charge. An alumina porous membrane modified with an organic compound was used.

  Modification of the organic compound having a sulfonic acid group to the through-hole of the alumina porous membrane was performed by the following method.

First, 0.1 g of an alkoxysilane compound (CH ₂ (—O—) CHCH ₂ O (CH ₂ ) ₃ Si (OCH ₃ ) ₃ ) containing an epoxy group at the end of an organic molecule was dissolved in 10 ml of a toluene solvent, One alumina porous membrane (outer diameter 47 mm) was immersed in the solution and reacted at 70 ° C. for 2 hours. By this step, a dealcoholization reaction occurred between the hydroxyl group (—OH) on the surface of the through-hole of the alumina porous membrane and the alkoxy group of the alkoxysilane compound, and the organic compound on the surface of the through-hole could be modified. . It is considered that the dealcoholization reaction proceeded as represented by the chemical formula shown in (Chemical Formula 14). The “surface” described in the chemical formula shown in (Chemical Formula 14) means the surface of the through-hole of the alumina porous membrane. The by-product alcohol is omitted.

  Next, a sulfonic acid machine was introduced into the organic compound modified on the surface of the through hole of the alumina porous membrane. The introduction of the sulfonic acid group was performed according to the following procedure. 0.4 g of sodium sulfite was dissolved in 15 ml of water, and the porous alumina membrane obtained by introducing an organic compound on the surface obtained in the previous step was immersed in this solution and reacted at 70 ° C. for 2 hours. Thereby, as shown in the chemical formula of (Chemical Formula 15), a sulfonic acid group was introduced into the surface of the through hole.

  The sulfonic acid group modified on the surface of the through-hole is obtained by immersing the obtained alumina porous membrane in a 0.1 mol / L lithium hydroxide aqueous solution, thereby substituting the terminal proton with lithium. Lithium sulfonate as shown in FIG.

(Example 3)
In Example 3, the same alumina porous film as in Example 1 was used as the inorganic porous film layer having a through-hole used for the electricity storage device, and the organic group having an amine group as a functional group having a negative charge on the surface of the through-hole was used. A porous alumina membrane modified with a compound was used.

  Modification of the organic compound having an amine group to the through-hole of the alumina porous membrane was performed by the following method.

First, 0.1 g of an alkoxysilane compound (H ₂ N— (CH ₂ ) ₃ Si (OCH ₃ ) ₃ ) containing an amine group at the end of an organic molecule was dissolved in 10 ml of a toluene solvent, and an alumina porous membrane was dissolved in this solution. One (outside diameter 47 mm) was immersed and reacted at 70 ° C. for 2 hours. By this step, a dealcoholization reaction occurred between the hydroxyl group (—OH) on the surface of the through-hole of the alumina porous membrane and the alkoxy group of the alkoxysilane compound, and the organic compound on the surface of the through-hole could be modified. . It is considered that the dealcoholization reaction proceeded as represented by the chemical formula shown in (Chemical Formula 17). The “surface” described in the chemical formula shown in (Chemical Formula 17) means the surface of the through-hole of the alumina porous membrane. The by-product alcohol is omitted.

(Evaluation of inorganic porous membrane)
Using the inorganic porous membrane obtained in Examples 1 to 3, the permeation rate of the eluted active material porous membrane was measured. If the permeation rate of the eluted active material is slow due to the presence of the inorganic porous membrane, it means that free movement of the eluted active material inside the porous membrane is suppressed, that is, the capacity reduction of the electricity storage device is suppressed. Means that you can.

  The permeation rate of the eluted active material permeating through the porous membrane was measured by the following method.

  The measurement was performed using the evaluation cell shown in FIG. In the evaluation cell shown in FIG. 4, an H-type glass cell 71 has a structure in which an inorganic porous membrane sample 74 is sandwiched between the two solution tanks 72 and 73. The elution active material solution was placed in one solution tank 72 across the inorganic porous membrane sample 74, and the organic solvent 73 containing no elution active material was placed in the other solution tank 73. In each solution tank, a stirrer 75 was placed and stirred with a magnetic stirrer.

As an elution active material solution to be placed in the solution tank 72, 40 ml of propylene carbonate (manufactured by Aldrich) in which 0.1% by weight of Tris (TTF) Bis (BF ₄ ) complex (manufactured by Tokyo Chemical Industry) was dissolved was used. As an organic solvent to be placed in the solution tank 73, 40 ml of propylene carbonate (manufactured by Aldrich) was used.

The permeation rate was evaluated by quantifying the concentration of the active material present in the solution tank 73 at regular intervals. The concentration of the active material was quantified by measuring UV-visible absorption spectrum.
The measurement results are shown in FIG.

  The triangular (▲), square (■), rhombus (♦), and circle (◯) data shown in FIG. 5 are in order when there is no inorganic porous film, and the inorganic porous film of Example 1 and Example 2 is data in the case of the inorganic porous membrane of No. 2 and the inorganic porous membrane of Example 3. FIG. As shown in FIG. 8, the active material permeates immediately when there is no inorganic porous membrane, whereas the permeation of the active material is suppressed when the inorganic porous membrane of Example 1 is used. I understand that. Further, as in Examples 2 and 3, by modifying the surface of the through-hole of the porous membrane with a functional group having a positive charge and a functional group having a negative charge, the permeation of the active material is suppressed. I understand that. The slope of the graph of FIG. 8 means the permeation rate of the active material, and a 99.9% permeation suppressing effect was obtained in Example 1 as compared with the case where there was no inorganic porous film. Moreover, compared with Example 1, the suppression effect of 20% was further obtained in Example 2, and the suppression effect of 30% was obtained in Example 3.

  Thus, by providing the electricity storage device having the inorganic porous membrane layer having the through hole between the positive and negative electrodes, it was possible to suppress the eluted active material from freely moving between the positive and negative electrodes. Thereby, the internal short circuit of an electrical storage device can be suppressed, and the capacity | capacitance fall of the charged electrical storage device can be suppressed.

  In addition, providing an inorganic porous membrane layer between the positive and negative electrodes provides a highly reliable electricity storage device that prevents a short circuit between the positive and negative electrodes because the inorganic porous membrane layer is excellent in heat resistance and mechanical strength. Can be said. In order to more efficiently use the effect of suppressing the movement of the effluent by the inorganic porous layer, for example, when using a rigid inorganic porous film as described in the examples, when incorporating this into a battery, an inorganic material is used as necessary. A sealing material may be disposed around the porous layer.

  The electricity storage device of the present invention can provide an electricity storage device with high output, light weight, and high capacity. These power storage devices can be used for various portable devices, transportation devices, uninterruptible power supplies, and the like.

Schematic cross-sectional view schematically showing the electricity storage device in Embodiment 1 of the present invention Schematic cross-sectional view of an inorganic porous membrane in Embodiment 2 of the present invention Schematic of the inside of the through-hole of the inorganic porous membrane in Embodiment 2 of the present invention Schematic of an evaluation cell for evaluating an inorganic porous membrane in an example of the present invention The figure which shows the evaluation result of the inorganic porous membrane in the Example of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Case 12 Positive electrode collector 13 Positive electrode 14 Inorganic porous membrane layer 15 Separator 16 Sealing board 17 Negative electrode collector 18 Negative electrode 19 Gasket 21 Through-hole 22 Surface of through-hole 23 Organic compound 24 Ionic functional group 71 H-type glass Cell 72 Solution tank 1
73 Solution tank 2
74 Inorganic porous membrane sample 75 Stirrer

Claims (9)

A power storage device including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte,
At least one of the positive electrode active material and the negative electrode active material includes an organic compound having a π electron conjugated cloud or an organic compound having a radical,
An electrical storage device comprising an inorganic porous film having a through hole between the positive electrode and the negative electrode. The surface of the through hole is modified with an organic compound having an ionic functional group,
The electricity storage device according to claim 1. The ionic functional group is a functional group having a positive charge;
The electricity storage device according to claim 2. The ionic functional group is a functional group having a negative charge;
The electricity storage device according to claim 2. The inorganic porous film having the through-hole is any one selected from the group consisting of metal oxides, glass and ceramics, or a mixture thereof;
The electricity storage device according to claim 2. The modification of the organic compound on the surface of the through hole is modified by a coupling reaction,
The electricity storage device according to claim 2. The electrical storage device according to claim 1, wherein the organic compound having the π-electron conjugated cloud has a structure represented by the general formula (1) or the general formula (2).
General formula (1):

(Wherein, X is a sulfur atom or an oxygen atom, R ^{1 to} R ⁴ are each an independent chain aliphatic group, cyclic aliphatic group, hydrogen atom, hydroxyl group, cyano group, amino group, nitro group or A nitroso group, wherein R ⁵ and R ⁶ are a hydrogen atom, a chain aliphatic group, and a cyclic aliphatic group, respectively, and the aliphatic group includes an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, (Including at least one selected from the group consisting of boron atoms and halogen atoms)
General formula (2):

(Wherein X is a nitrogen atom, R ^{1 to} R ⁴ are each an independent chain aliphatic group, cyclic aliphatic group, hydrogen atom, hydroxyl group, cyano group, amino group, nitro group or nitroso group. , R5, and R6 are each a hydrogen atom, a chain aliphatic group, or a cyclic aliphatic group, and the aliphatic group includes an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom, and a halogen atom. Including at least one selected from the group consisting of :) The electricity storage device according to claim 1, wherein the organic compound having the π electron conjugated cloud has a structure represented by the general formula (3).
General formula (3):

Wherein X ^{1 to} X ⁴ are each independently a sulfur atom, oxygen atom, selenium atom, tellurium atom, and R ^{1 to} R ² are each an independent chain aliphatic group or cyclic aliphatic group, The aliphatic group includes 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.)   The electricity storage device according to claim 1, wherein the organic compound having a radical has at least one of a nitroxy radical and an oxygen radical in a molecule.