JP2018160404A - Vanadium redox secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vanadium redox secondary battery in which generation of CO 2 gas due to an oxidation reaction on the positive electrode side is suppressed, adhesion between an electrode and a current collector is favorably maintained, and which has favorable charge/discharge characteristics. A battery (1) includes a positive electrode current collector (53), an active material disposed on one surface of the positive electrode current collector (53) and containing vanadium ions or vanadium-containing ions, and an acidic electrolyte. A positive electrode electrode (50) containing N, a negative electrode current collector (63), an active material disposed on one surface of the negative electrode current collector (63) and containing vanadium ions or vanadium-containing ions, and an acidic electrolytic solution. It includes a negative electrode (60) including the same, and a diaphragm (7) partitioning the positive electrode (50) and the negative electrode (60). The positive electrode current collector (53) contains a carbon material, and the full width at half maximum of the diffraction peak obtained by X-ray diffraction of the carbon material is 1.28° or less. [Selection diagram] Figure 2

Description

  The present invention relates to a vanadium redox secondary battery that contains vanadium ions or vanadium-containing ions as an active material and performs charge / discharge using an oxidation-reduction reaction by the active material.

  Secondary batteries are widely used in digital home appliances, electric vehicles, hybrid vehicles, solar power generation facilities, and the like. Examples of the battery include a lithium ion secondary battery and a vanadium redox secondary battery. The vanadium redox secondary battery performs charge and discharge by changing the valence of ions using two sets of redox pairs. As the active material, vanadium ions or ions containing vanadium are used.

  The vanadium redox secondary battery is different in polarity from an electrode material including an active material, a carbon material as a conductive auxiliary agent, and an electrode having an acidic electrolyte such as sulfuric acid and a conductor such as copper on which the electrode is disposed. A plurality of electrode materials are arranged in parallel with each other through a diaphragm and are housed in an exterior bag. The vanadium redox secondary battery may be further accommodated in a case.

  Patent Document 1 discloses an invention of a vanadium redox secondary battery including an electrode having an ion containing vanadium whose oxidation number changes between pentavalent and tetravalent by an oxidation-reduction reaction as an active material of a positive electrode. Yes. In order to prevent corrosion of the conductor due to the electrolytic solution, it is disclosed that the surface of the conductor is covered with a protective layer having conductivity and non-permeability of the electrolytic solution, such as a carbon sheet. A current collector is constituted by the protective layer and the conductor.

Japanese Patent Laid-Open No. 2006-186861

However, in the vanadium redox secondary battery of Patent Document 1, in the battery reaction, the protective layer on the positive electrode side may be oxidized and CO ₂ may be generated.
The generated CO ₂ reduces the adhesion between the electrode and the current collector, which may adversely affect the charge / discharge characteristics of the vanadium redox secondary battery.

  The present invention has been made in view of such circumstances, and provides a vanadium redox secondary battery in which the generation of gas is suppressed, the adhesion between the electrode and the current collector is well maintained, and the battery has good charge / discharge characteristics. The purpose is to provide.

  The vanadium redox secondary battery according to the present invention includes a plate-like positive electrode current collector and a vanadium which is disposed on one surface of the positive electrode current collector and whose oxidation number varies between pentavalent and tetravalent by an oxidation-reduction reaction. An active material containing ions or vanadium ions whose oxidation number changes between pentavalent and tetravalent, a positive electrode containing an acidic electrolyte, a plate-like negative electrode current collector, and the negative electrode current collector Active material containing vanadium ions which are arranged on one side and whose oxidation number changes between divalent and trivalent or vanadium whose oxidation number changes between divalent and trivalent by oxidation-reduction reaction And a negative electrode containing an acidic electrolyte, and a positive electrode and a diaphragm partitioning the negative electrode, wherein the positive current collector contains a carbon material, and has a diffraction peak obtained by X-ray diffraction of the carbon material. Half width at half maximum is 1.28 ° It characterized in that it is a below.

  According to the present invention, the generation of gas from the protective layer is suppressed, the adhesion between the electrode and the current collector is maintained well, and the battery has good charge / discharge characteristics.

1 is a schematic plan view of a vanadium redox secondary battery according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. It is a graph showing the relationship between the generated amount of half width at half maximum and the CO ₂ gas of the carbon material of the positive electrode side. Is a graph showing the relationship between the generated amount of half width at half maximum and H ₂ gas of the carbon material of the negative electrode side.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
1. Vanadium Redox Secondary Battery As shown in FIGS. 1 and 2, a vanadium redox secondary battery 1 (hereinafter referred to as a battery 1) according to the embodiment protrudes from an outer bag 2 and a part of a peripheral edge of the outer bag 2. The positive electrode terminal 3 and the negative electrode terminal 4, the positive electrode material 5, the negative electrode material 6, and the diaphragm 7 are provided. The positive electrode terminal 3 and the negative electrode terminal 4 protrude from a part of the peripheral edge portion of the outer bag 2 in a state where the base end side is covered with the sealing materials 30 and 40. The battery 1 alone or a combination of the battery 1 and another battery 1 may be accommodated in a case (not shown).

The electrode material 5 includes an electrode 50, a conductor 51, a protective layer 52, and a sealant 54. A current collector 53 is constituted by the conductor 51 and the protective layer 52.
The conductor 51 has a rectangular flat plate shape and is disposed on the upper surface of the lower half 22 in FIG. 2 of the outer bag 2, and the upper surface of the conductor 51 is covered with a protective layer 52. The protective layer 52 is conductive and has no electrolyte solution permeability. Inside the peripheral edge of the upper surface of the protective layer 52, a square plate-like electrode 50 having an active material, a carbon material as a conductive additive, a binder, and an acidic electrolyte is provided.
The sealant 54 has a frame shape having an edge portion, and is bonded to the peripheral edge portion and the half body 22. The conductor 51 is sealed by the half body 22 and the protective layer 52.

Hereinafter, each part of the electrode material 5 and the half body 22 of the exterior bag 2 will be described in detail.
The half 22 is electrolyte impermeable. The half 22 is preferably composed of a laminate sheet containing a synthetic resin layer and a metal layer.
Examples of the material for the synthetic resin layer include polypropylene, polyethylene, polyamide such as nylon 6, nylon 66, and the like. Examples of the material for the metal layer include aluminum, aluminum alloy, copper, copper alloy, iron, stainless steel, titanium, and titanium alloy.
Although the thickness of the half body 22 is not specifically limited, It is preferable that it is 15-250 micrometers. When thickness is 15-250 micrometers, while having sufficient intensity | strength, the volume energy density of a battery improves.

The planar area of the conductor 51 is smaller than the planar area of the half body 22.
The conductor 51 is preferably made of a metal foil such as copper, aluminum, or nickel. The thickness is preferably 5 to 100 μm. When the thickness is 100 μm or less, the volume energy density and weight energy density of the battery are improved.
The conductor 51 has a tab (not shown) protruding from a part of the peripheral edge, and the tip of the tab is connected to the positive electrode terminal 3.

The protective layer 52 contains a carbon material, and the half-value half width of a diffraction peak obtained by X-ray diffraction of the carbon material is 1.28 ° or less, and the crystallinity is high. The half width at half maximum is preferably 0.06 ° or more from the viewpoint of material availability. The upper limit of the half width at half maximum is preferably 1.11 °.
Examples of the carbon material include carbon nanotube (CNT), carbon black, graphite, and the like, and one or more of these can be used. In this case, one having a half width at half maximum of 1.28 ° or less, high crystallinity, and good conductivity can be easily selected. When acetylene black is selected as the carbon material, it may melt and open a hole in the protective layer 52.

  The protective layer 52 is preferably formed by coating the conductor 51 with the carbon material dispersed in a thermosetting resin such as polyolefin containing polypropylene, or a thermoplastic resin such as epoxy resin. For example, a carbon material is blended in a thermosetting resin or a thermoplastic resin, mixed with a stirrer, and the obtained mixture is applied to the conductor 51.

For the protective layer 52, a graphite sheet containing the graphite may be provided on one surface of the conductor 51 via, for example, a conductive adhesive sheet.
For the protective layer 52, a conductive film formed by kneading the carbon material into a base film or applying the CNT ink to the base film may be provided via, for example, a conductive adhesive sheet. .
The protective layer 52 may be formed by coating one surface of the conductor 51 with graphite.
The thickness of the protective layer 52 is preferably 1 to 100 μm. In this case, a decrease in electrical conductivity between the electrode 50 and the conductor 51 can be suppressed, and the internal resistance of the battery 1 can be reduced.

Note that the current collector 53 is not limited to the case where the current collector 53 has a two-layer structure of the conductor 51 and the protective layer 52, and the current collector 53 may have a single-layer structure. For example, the graphite sheet can be used as the current collector 53.
In the case of the two-layer structure, the current collector 53 has the conductor 51, so that the current collection efficiency is good, and the protective layer 52 containing the carbon material is provided on the surface of the conductor 51. In a reduced state, the corrosion of the conductor 51 by the acidic electrolyte is favorably prevented, which is preferable.

As described above, the electrode 50 is provided inside the peripheral edge of the upper surface of the protective layer 52, that is, at a portion other than the peripheral edge of the upper surface of the protective layer 52.
The electrode 50 includes a carbon material and vanadium (V) ions whose oxidation number changes between pentavalent and tetravalent by an oxidation-reduction reaction, or ions containing V whose oxidation number changes between pentavalent and tetravalent. A solid compound containing a vanadium solid salt containing as a positive electrode active material.

The pentavalent and ions containing the V oxidation number changes between ^{tetravalent, VO 2+ (IV), VO} 2 + (V) are exemplified.
Examples of the vanadium compound that is an active material for the positive electrode include vanadium sulfate (IV) (VOSO ₄ · nH ₂ O) and vanadium sulfate (V) ((VO ₂ ) ₂ SO ₄ · nH ₂ O). it can. N represents an integer of 0 to 6.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and a copolymer of vinylidene fluoride and hexafluoropropylene (PVDF / HFP).

Examples of the carbon material of the electrode 50 include carbon black such as acetylene black and ketjen black (registered trademark), and graphite. The carbon material can use 1 type (s) or 2 or more types.
The acidic electrolyte contained in the electrode 50 is preferably an aqueous sulfuric acid solution. As the sulfuric acid aqueous solution, for example, sulfuric acid having a concentration of less than 90% by mass can be used. The amount of the electrolytic solution is not an excess or deficiency to obtain 0 to 100% of the SOC of the battery. The amount of the electrolytic solution is, for example, 70 mL of 2M (mol / L) sulfuric acid with respect to 100 g of the vanadium compound.

  The sealant 54 has a frame shape as described above, and includes an inner edge portion 54a projecting inwardly at the upper end portion of the rectangular tube-shaped frame body, and an outer edge portion 54b projecting outwardly at the lower end portion of the frame body. Prepare. That is, the sealant 54 is configured such that the outer edge portion 54b is positioned outside the inner edge portion 54a (the outer portion of the electrode 50) in plan view.

The inner edge 54 a of the sealant 54 is bonded to the peripheral edge of the upper surface of the protective layer 52, and the inner side surface of the inner edge 54 a is bonded to the side surface of the electrode 50. The inner side surface of the inner edge portion 54 a may not be bonded to the side surface of the electrode 50.
The outer edge portion 54 b is bonded to the outer surface of the conductor 51 on the surface of the half body 22 on the conductor 51 side. Thereby, the conductor 51 and the protective layer 52 are sandwiched between the half body 22 and the sealant 54. That is, the conductor 51 is fixed to the half body 22 in a state where the conductor 51 is sealed by the half body 22, the protective layer 52, and the sealant 54. In addition, the side surface of the conductor 51 may be bonded to the sealant 54, or may not be bonded.

  Examples of the material of the sealant 54 include polypropylene or polyethylene. By using polypropylene or polyethylene, the conductor 51 can be easily sealed by heat welding.

The electrode material 6 has the same configuration as the electrode material 5, and includes an electrode 60, a conductor 61, a protective layer 62, and a sealant 64. A current collector 63 is configured by the conductor 61 and the protective layer 62.
The conductor 61 has a rectangular flat plate shape and is disposed on the lower surface of the half body 21 of the outer bag 2 in FIG. 2, and the lower surface of the conductor 61 is covered with a protective layer 62. On the inner side of the peripheral edge portion of the lower surface of the protective layer 62, a square plate electrode 60 having an active material, a carbon material, a binder, and an acidic electrolyte is provided. The sealant 64 has a frame shape, and includes an inner edge portion 64a projecting inwardly at the lower end portion of the rectangular tube-shaped frame body, and an outer edge portion 64b projecting outward at the upper end portion of the frame body. The inner edge portion 64 a is bonded to the peripheral edge portion, the outer edge portion 64 b is bonded to the half body 21, and the sealant 64 seals the conductor 61 by the half body 21 and the protective layer 62.
The conductor 61 of the electrode material 6 has a tab (not shown) protruding from a part of the peripheral edge, and the tip of the tab is connected to the negative electrode terminal 4.
The conductor 61 and the sealant 64 of the electrode material 6 are made of the same material as the electrode material 5.

The protective layer 62 preferably contains a carbon material, and the half width at half maximum of the diffraction peak obtained by X-ray diffraction of the carbon material is preferably 1.1 ° or more. The half width at half maximum is preferably 3.73 ° or less from the viewpoint of material availability. The lower limit of the half width at half maximum is more preferably 1.3 °.
Examples of the carbon material include acetylene black. In this case, one having a half width at half maximum of 1.1 ° or more and having good conductivity can be easily selected.

  The protective layer 62 is preferably formed by coating the conductor 61 with the carbon material dispersed in a thermosetting resin such as polyolefin containing polypropylene, or a thermoplastic resin such as epoxy resin. For example, a carbon material is blended in a thermosetting resin or a thermoplastic resin, mixed with a stirrer, and the obtained mixture is applied to the conductor 61.

The protective layer 62 is formed by forming the carbon material into a sheet shape, applying a carbon film ink to a base film, or kneading the carbon material into the base film, for example, a conductive film. You may decide to provide through this adhesive sheet.
The thickness of the protective layer 62 is preferably 1 to 100 μm. In this case, a decrease in electrical conductivity between the electrode 60 and the conductor 61 can be suppressed, and the internal resistance of the battery 1 can be reduced.

The current collector 63 is not limited to the case where it has a two-layer structure of the conductor 61 and the protective layer 62, and the current collector 63 may have a single layer structure. For example, the sheet can be used as a current collector.
In the case of the two-layer structure, the current collector 63 has the conductor 61, so that the current collection efficiency is good, and the protective layer 62 containing the carbon material is provided on the surface of the conductor 60. In a reduced state, the corrosion of the conductor 61 by the electrolytic solution is favorably prevented, which is preferable.

  The electrode 60 contains a carbon material and V ions whose oxidation number changes between divalent and trivalent by oxidation-reduction reaction, or ions containing V whose oxidation number changes between divalent and trivalent. A solid compound containing a vanadium solid salt as a negative electrode active material is included.

Examples of the V ions whose oxidation number changes between divalent and trivalent include V ²⁺ (II) and V ³⁺ (III).
Examples of the vanadium compound that is an active material for the negative electrode include vanadium sulfate (II) (VSO ₄ · nH ₂ O) and vanadium sulfate (III) (V ₂ (SO ₄ ) ₃ · nH ₂ O). N represents an integer of 0 to 10.

The diaphragm 7 is an anion exchange membrane, and is adhered to the upper surface of the inner edge portion 54 a of the sealant 54 and the lower surface of the inner edge portion 64 a of the sealant 64.
The diaphragm 7 can pass hydrogen ions (protons) or sulfate ions.

Reactions of the following formulas (1) and (2) occur between the electrode 50 of the electrode material 5 and the electrode 60 of the electrode material 6 of the battery 1 configured as described above.
Positive electrode: VOX ₂ · nH ₂ O (s) ⇔VO ₂ X · (n−1) H ₂ O (s) + HX + H ⁺ + e ⁻ (1)
Negative electrode: VX ₃ · nH ₂ O (s) + H ⁺ + e ⁻ ⇔VX ₂ · nH ₂ O (s) + HX (2)
In the formula, X represents a monovalent anion. When X is an m-valent anion, the coupling coefficient (1 / m) is considered. n can take various values.

  Charging / discharging of the vanadium redox secondary battery 1 is performed using reaction of said Formula (1) and (2). At this time, charging / discharging is performed with an external load or a charger via the positive terminal 3 and the negative terminal 4. In the reaction of the formulas (1) and (2), protons move between the electrodes 50 and 60 through the diaphragm 7.

The reaction of each material when VOSO ₄ · nH ₂ O is used as the vanadium compound of the electrode material 5 and V ₂ (SO ₄ ) ₃ · nH ₂ O is used as the vanadium compound of the electrode material 6 is shown below.
Positive electrode: 2VOSO ₄ · nH ₂ O (s) ⇔ (VO ₂ ) ₂ SO ₄ · (n−2) H ₂ O (s) + H ₂ SO ₄ + 2H ⁺ + 2e ⁻ (3)
Negative electrode: V ₂ (SO ₄ ) ₃ · nH ₂ O (s) + 2H ⁺ + 2e ⁻ ⇔2VSO ₄ · nH ₂ O (s) + H ₂ SO ₄ (4)

  In the battery 1 according to this embodiment configured as described above, the conductor 51 is sealed by the sealant 54, the protective layer 52, and the half body 22, and the electrode 50 is surrounded by the diaphragm 7 and the sealant 54a. Yes. Therefore, the acidic electrolyte contained in the electrode 50 does not come into contact with the conductor 51, and corrosion of the conductor 51 is prevented. Similarly, the conductor 61 is sealed by the sealant 64, the protective layer 62, and the half body 21, and the electrode 60 is surrounded by the diaphragm 7 and the sealant 64a. Therefore, the acidic electrolyte contained in the electrode 60 does not react with the conductor 61, and corrosion of the conductor 61 is prevented.

In the present embodiment, since the current collector 53 on the positive electrode side contains the above-described carbon material, the generation of CO ₂ gas is suppressed, and the adhesion between the electrode 50 and the current collector 53 is favorably maintained. .
Further, since the current collector 63 on the negative electrode side contains the above-described carbon material, generation of H ₂ gas due to the reduction of the electrolyte is suppressed, and the adhesion between the electrode 60 and the current collector 63 is maintained well. The
Therefore, the battery 1 has good charge / discharge characteristics.

2. Relationship between the half-width at half maximum of the carbon material on the positive electrode side and gas generation Prepare multiple types of carbon materials as carbon materials to be included in the current collector on the positive side, and find the half-width at half maximum of the diffraction peak obtained by X-ray diffraction, respectively. It was. The measurement apparatus and measurement conditions are as follows.
Measuring device: XRD-MultiFlex
Measurement conditions X-Ray: 40kV / 40mA
Divergence: 1 °
Scattering: 1 °
Light reception: 0.15mm

To 5 mL of a solution prepared by mixing sulfuric acid with a 1 M aqueous solution of vanadium sulfate (V) ((VO ₂ ) ₂ SO ₄ ) hydrate as a pentavalent vanadium compound so that the free sulfuric acid concentration is 2 M, 0.1 g of the material was added and allowed to stand in an environment of 25 ° C. for 2 weeks, and the amount of CO ₂ generated was measured by gas chromatography.

FIG. 3 is a graph showing the relationship between the half width at half maximum of the carbon material and the amount of CO ₂ gas generated.
FIG. 3 shows that when the half width at half maximum of the carbon material is 1.28 ° or less, the amount of CO ₂ gas generated is 4000 ppm or less.
The minimum value of the half width at half maximum of the tested carbon material is 0.06 °. This value is considered to be approximately equal to the minimum half-value half-width of available carbon materials.
In the carbon material in which the generation amount of CO ₂ gas is 4000 ppm or less, the maximum value of the half width at half maximum of the used carbon material was 1.11 °.
From FIG. 3, it is found that the half-value half width of the carbon material is 1.28 ° or less, the lower limit value of the half value half width is preferably 0.06 °, and the upper limit value of the half value half width is preferably 1.11 °.
From the above, when the half width at half maximum of the carbon material is 1.28 ° or less, the generation of CO ₂ gas is suppressed, the adhesion between the electrode 50 and the current collector is maintained well, and the battery 1 is charged and discharged satisfactorily. It can be seen that it has characteristics.

3. Relationship between the half-width at half maximum of the carbon material on the negative electrode side and gas generation Prepare multiple types of carbon materials as carbon materials to be included in the current collector on the negative electrode side, and find the half-width at half maximum of the diffraction peak obtained by X-ray diffraction, respectively. It was. The measurement apparatus and measurement conditions are the same as described above.

The carbon material is added to 5 mL of a solution prepared by mixing sulfuric acid with a free sulfuric acid concentration of 2 M in a 1 M aqueous solution of vanadium sulfate (II) (VSO ₄ · nH ₂ O) hydrate as a divalent vanadium compound. 0.1 g was added and allowed to stand in an environment of 25 ° C. for 2 weeks, and the amount of H ₂ generated was measured by gas chromatography.

FIG. 4 is a graph showing the relationship between the half width at half maximum of the carbon material and the amount of H ₂ gas generated.
FIG. 4 shows that when the half width of the carbon material is 1.1 ° or more, the generation amount of H ₂ gas is 2000 ppm or less.
The maximum half-value half-width of the tested carbon material is 3.73 °. This value is considered to be approximately equal to the maximum half-value half-width of available carbon materials.
From FIG. 4, it is found that the half width at half maximum of the carbon material is 1.1 ° or more, the upper limit value of the half width at half maximum is preferably 3.73 °, and the lower limit value of the half width at half maximum is preferably 1.3 °.
From the above, when the half width at half maximum of the carbon material is 1.1 ° or more, the generation of H ₂ gas is suppressed, the adhesion between the electrode 60 and the current collector 63 is maintained well, and the battery 1 is satisfactorily charged. It can be seen that it has discharge characteristics.

  As described above, the vanadium redox secondary battery according to the present invention is arranged on a flat positive electrode current collector and one surface of the positive electrode current collector, and is oxidized between pentavalent and tetravalent by an oxidation-reduction reaction. An active material containing vanadium ions whose number changes, or ions containing vanadium whose oxidation number changes between pentavalent and tetravalent, and a positive electrode containing an acidic electrolyte, a plate-like negative electrode current collector, Ion containing vanadium ion which is arranged on one surface of the negative electrode current collector and whose oxidation number changes between divalent and trivalent by oxidation-reduction reaction, or vanadium whose oxidation number changes between divalent and trivalent A positive electrode containing an active material containing an acidic electrolyte, and a diaphragm partitioning the positive electrode and the negative electrode, the positive electrode current collector containing a carbon material, and by X-ray diffraction of the carbon material Half value half of the obtained diffraction peak It is 1.28 ° or less.

In the present invention, the generation of CO ₂ gas is suppressed on the positive electrode side, the adhesion between the electrode and the current collector is maintained well, and the battery has good charge / discharge characteristics.

  In the above vanadium redox secondary battery, the negative electrode current collector contains a carbon material, and a half-value half width of a diffraction peak obtained by X-ray diffraction of the carbon material of the negative electrode current collector is 1.1 ° or more. Is preferred.

In the present invention, generation of H ₂ gas is suppressed on the negative electrode side due to the reduction of the electrolytic solution, the adhesion between the electrode and the current collector is maintained well, and the battery has good charge / discharge characteristics.

  In the above-described vanadium redox secondary battery, it is preferable that the half-value half width of the carbon material of the positive electrode current collector is 0.06 ° or more.

In the present invention, generation of CO ₂ gas is favorably suppressed on the positive electrode side.

  In the vanadium redox secondary battery described above, the negative electrode current collector includes a carbon material, and a half-value half width of a diffraction peak obtained by X-ray diffraction of the carbon material of the negative electrode current collector is 3.73 ° or less. Is preferred.

In the present invention, generation of H ₂ gas is satisfactorily suppressed on the negative electrode side.

  In the vanadium redox secondary battery described above, the negative electrode current collector includes a carbon material, and the carbon material included in the positive electrode current collector is one or more selected from CNT, carbon black, and graphite, The carbon material contained in the negative electrode current collector is preferably acetylene black.

When the carbon material contained in the positive electrode current collector is selected from CNT, carbon black, and graphite, the half width at half maximum is 1.28 ° or less, the crystallinity is high, and the material has good conductivity. Can be selected easily. For example, when acetylene black having low crystallinity is selected as the carbon material, it may be decomposed by an oxidation reaction to open a hole in the current collector.
When the carbon material contained in the negative electrode current collector is acetylene black, it is possible to easily select those having a half width at half maximum of 1.1 ° or more and having good conductivity.

  In the above-described vanadium redox secondary battery, each of the positive electrode current collector and the negative electrode current collector includes a metal layer and a coating layer that includes a carbon material and covers the metal layer, and the coating layer includes the above-described coating layer. It is preferable that the positive electrode or the negative electrode is disposed.

  In the present invention, since the current collector has a metal layer, the current collection efficiency is good, and since the coating layer containing the carbon material is provided on the surface of the metal layer, the amount of the carbon material is reduced, Corrosion of the metal layer due to the electrolytic solution is well prevented.

  In the above-described vanadium redox secondary battery, it is preferable that the carbon material is dispersed in a thermosetting resin or a thermoplastic resin in the coating layer.

  In the present invention, since the carbon material is dispersed in the thermosetting resin or the thermoplastic resin, the coating layer can be uniformly conductive and non-permeable to electrolyte.

The present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.
For example, the vanadium redox secondary battery is not limited to the case of including a pair of electrode materials, and may include a plurality of pairs of electrode materials.
Moreover, it is not limited to the case where the sealants 54 and 64 are provided.

DESCRIPTION OF SYMBOLS 1 Vanadium redox secondary battery 2 Exterior bag 3 Positive electrode terminal 4 Negative electrode terminal 5, 6 Electrode material 50 Electrode (positive electrode)
60 electrodes (negative electrode)
51, 61 Conductor 52, 62 Protective layer 53 Current collector (positive electrode current collector)
63 Current collector (Negative electrode current collector)
54, 64 Sealant 7 Diaphragm

Claims (7)

A plate-like positive electrode current collector;
An ion containing vanadium ion which is arranged on one surface of the positive electrode current collector and whose oxidation number changes between pentavalent and tetravalent by oxidation-reduction reaction, or vanadium whose oxidation number changes between pentavalent and tetravalent. A positive electrode containing an active material containing an acidic electrolyte, and
A plate-like negative electrode current collector;
Ion containing vanadium ion which is arranged on one surface of the negative electrode current collector and whose oxidation number changes between divalent and trivalent by oxidation-reduction reaction, or vanadium whose oxidation number changes between divalent and trivalent A negative electrode containing an active material containing an acidic electrolyte, and
A diaphragm that partitions the positive electrode and the negative electrode,
The positive electrode current collector includes a carbon material,
A vanadium redox secondary battery, wherein a half-width of a diffraction peak obtained by X-ray diffraction of the carbon material is 1.28 ° or less. The negative electrode current collector includes a carbon material,
2. The vanadium redox secondary battery according to claim 1, wherein a half-width at half maximum of a diffraction peak obtained by X-ray diffraction of the carbon material of the negative electrode current collector is 1.1 ° or more.   3. The vanadium redox secondary battery according to claim 1, wherein a half width at half maximum of the carbon material of the positive electrode current collector is 0.06 ° or more. 4. The negative electrode current collector includes a carbon material,
4. The vanadium according to claim 1, wherein a half-width of a diffraction peak obtained by X-ray diffraction of the carbon material of the negative electrode current collector is 3.73 ° or less. 5. Redox secondary battery. The negative electrode current collector includes a carbon material,
The carbon material contained in the positive electrode current collector is at least one selected from carbon nanotubes, carbon black, and graphite,
The vanadium redox secondary battery according to any one of claims 1 to 4, wherein the carbon material contained in the negative electrode current collector is acetylene black. Each of the positive electrode current collector and the negative electrode current collector has a metal layer and a coating layer that includes a carbon material and covers the metal layer,
The vanadium redox secondary battery according to any one of claims 1 to 5, wherein the positive electrode or the negative electrode is disposed on the coating layer.   The vanadium redox secondary battery according to claim 6, wherein the carbon material of the coating layer is dispersed in a thermosetting resin or a thermoplastic resin.

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