WO2017069261A1 - Redox cell - Google Patents
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- WO2017069261A1 WO2017069261A1 PCT/JP2016/081324 JP2016081324W WO2017069261A1 WO 2017069261 A1 WO2017069261 A1 WO 2017069261A1 JP 2016081324 W JP2016081324 W JP 2016081324W WO 2017069261 A1 WO2017069261 A1 WO 2017069261A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/96—Carbon-based electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- the present invention relates to a redox battery, and more particularly to a redox battery capable of improving charge and discharge efficiency by suppressing increase in battery internal resistance due to decrease in conductivity and viscosity and increase in solution resistance in a high concentration active material liquid.
- Non-Patent Documents 1 to 3 an attempt is made to increase the vanadium concentration in the active material liquid in order to increase the output density and energy density in the redox flow battery.
- Non-Patent Documents 1 and 2 report on a sulfuric acid pentavalent vanadium-containing liquid that can be used as a positive electrode active material liquid.
- Non-Patent Document 1 clarifies that precipitation of a vanadium salt is likely to occur when the vanadium concentration exceeds 2.0 M in a sulfuric acid pentavalent vanadium-containing liquid.
- this precipitate can be temporarily redissolved by adding sulfuric acid to the pentavalent vanadium-containing liquid in which precipitation has occurred and heating.
- the positive electrode active material liquid obtained in this way is considered to be unfavorable in terms of voltage efficiency in charge and discharge because a reversible decrease is observed in the cyclic voltammogram. This is due to a significant decrease in fluidity of the active material liquid, and Non-Patent Document 1 concludes that such a high-concentration active material system is not practical as a result.
- Non-Patent Document 2 also reports the same knowledge as Non-Patent Document 1 based on the cyclic voltammogram.
- Non-Patent Document 3 reports a divalent and trivalent vanadium-containing liquid that can be used as a negative electrode active material liquid.
- Non-Patent Document 3 calculates the diffusion coefficient for each of divalent and trivalent vanadium in the liquid by chronopotentiometry in order to estimate what complex form vanadium exists in the negative electrode active material liquid.
- the Stokes radius of the chemical species is calculated from the actually measured viscosity.
- the calculated Stokes radius is an ako complex, specifically V 2+ (H 2 O) 6 or V 3+ (H 2 O) 6 , which has been conventionally considered as a chemical species of divalent and trivalent vanadium. It is confirmed that it is almost the same as the Stokes radius.
- Non-Patent Document 3 the negative electrode liquid side containing vanadium divalent and trivalent is a hydrated ion and forms a complex with another ligand. It was thought not. However, unlike a dilute system of 1M or less, a system exceeding 1.5M exhibits solid properties, so a corresponding idea is important. Vanadium is not simply the charge bearer, but rather a strong contribution from protons, which is also inferred from the NMR spectrum. In addition, such a solution strongly exhibits Bingham fluidity. As a result, the ion diameter cannot be evaluated using the Stokes equation.
- Non-Patent Document 3 prepares a 1.6 M solution as “practical vanadium concentration”.
- the concentration of the conventional negative electrode active material liquid capable of preventing the deposition of vanadium and continuing the charge and discharge stably is about 1.5M to 1.7M. Therefore, the concentration described in Non-Patent Document 3 can be said to be a reasonable value from the conventional viewpoint.
- a conventional negative electrode active material liquid containing an acidic vanadium sulfate compound liquid is also difficult to maintain sufficient electrode reactivity and fluidity, particularly when vanadium is used at a high concentration, and is stable and energy efficient. The battery could not be charged and discharged.
- an object of the present invention is to provide a redox battery capable of improving charge and discharge efficiency by suppressing increase in battery internal resistance due to decrease in conductivity and viscosity and increase in solution resistance in a high concentration active material liquid.
- the redox battery characterized in that the diaphragm has an ion exchange capacity of 2.0 (meq / g-dry ion exchange membrane) or more and a film thickness of 120 ⁇ m or less.
- Each of the positive electrode active material liquid and the negative electrode active material liquid contains vanadium as an active material, the content of vanadium atoms is 100 g / L or more, and the content of sulfur atoms as sulfate and hydrogen sulfate radicals It is 120 g / L or more,
- the redox battery of Claim 1 or 2 characterized by the above-mentioned.
- a redox battery capable of improving charge and discharge efficiency by suppressing increase in battery internal resistance due to decrease in conductivity and viscosity and increase in solution resistance in a high concentration active material liquid.
- heat treatment in an oxidizing atmosphere such as mixing some air in the furnace (for example, including an oxidizing treatment in a nitrogen atmosphere by mixing about 0.1% of air)
- heat treatment in an atmosphere in which water vapor and an etching agent such as an aluminum compound are mixed can be preferably used.
- Oxidation-treated carbon fibers have improved mass mobility due to the small fiber diameter, the diffusion of the electrolyzed material becomes more multi-dimensional (for example, from 2D to 2.5D diffusion), and the surface is graphitic. Since it becomes carbon, electrode reactivity (charge transfer reactivity) is also improved. Because of these synergistic actions, the positive electrode 11 and the negative electrode 21 have an effect of being able to perform electrolysis with a high current density with respect to the substance to be electrolyzed, and therefore, oxidized carbon fibers are more preferable.
- the inventor initially reduced the thickness of the positive electrode 11 and the negative electrode 21 to 3 mm or less in the case of a flow type battery and to 6 mm or less in the case of a static or intermittent flow type battery, respectively.
- the trapping property of the substance was suppressed, which was considered undesirable.
- the thickness of the positive electrode 11 and the negative electrode 21 is reduced to 3 mm or less in the case of a flow type battery and to 6 mm or less in the case of a stationary or intermittent flow battery, respectively.
- the positive electrode cell 1 is provided with an inlet 12 for flowing the positive electrode active material liquid into the positive electrode cell 1 and an outlet 13 for flowing the positive electrode active material liquid in the positive electrode cell 1. .
- the negative electrode active material liquid stored in the negative electrode active material liquid tank 24 is configured to flow into the negative electrode cell 2 through the inflow pipe 26 connected to the inflow port 22 when the pump 25 is driven. .
- the negative electrode active material liquid that has flowed out of the outlet 23 is returned to the negative electrode active material liquid tank 24 through an outlet pipe 27 connected to the outlet 23. In this way, a circulation system for circulating and supplying the negative electrode active material liquid from the negative electrode active material liquid tank 24 into the negative electrode cell 2 is configured.
- conductive sheets 5 and 5 are provided so as to be in contact with each of the positive electrode 11 and the negative electrode 21, and the entire cell is sandwiched by the pressing plates 6 and 6 from the outside of the conductive sheets 5 and 5.
- the positive electrode 11 and the negative electrode 21 can be connected to an external circuit via the conductive sheets 5 and 5, respectively.
- the active material concentration of each of the positive electrode active material liquid and the negative electrode active material liquid is as high as 1.8 M or more, and by using the diaphragm 3 having the specific ion exchange capacity and film thickness described above.
- the effect of improving the charge / discharge efficiency by suppressing the decrease in conductivity and the increase in battery internal resistance due to increase in viscosity and solution resistance in high-concentration active material liquid is obtained. It is done.
- a redox battery (also referred to as a redox flow battery) in which the positive electrode active material liquid is circulated to the positive electrode and the negative electrode active material liquid is circulated to the negative electrode is mainly shown, but the present invention is not limited to this.
- the positive electrode active material liquid having an active material concentration of 1.8 M or more and the negative electrode active material liquid are used, and the ion exchange capacity
- a diaphragm having a thickness of 2.0 (meq / g-dry ion exchange membrane) or more and a film thickness of 120 ⁇ m or less the effect of the present invention is exhibited as in the case where the active material is passed through the electrode.
- the cell area resistivity is preferably lowered by setting the thickness of the positive electrode and the negative electrode to 3 mm or less, respectively. I understand.
Abstract
The present invention addresses the problem of providing a redox cell that inhibits rises in the cell internal resistance due to a decrease in conductivity and an increase in the viscosity and solution resistance in a high-concentration active material liquid, and makes it possible to improve the charging/discharging efficiency. The present invention is characterized in that the redox cell is provided with a positive electrode 11 in which a positive electrode active material liquid is impregnated or circulated, a negative electrode 21 in which a negative electrode active material liquid is impregnated or circulated, and a barrier membrane 3 provided between the positive electrode 11 and the negative electrode 21, the positive electrode active material liquid and the negative electrode active material liquid both having an active material concentration of at least 1.8M, the barrier membrane 3 having an ion exchange capacity of at least 2.0 (meq/g - dry ion exchange membrane), and the membrane thickness being 120 µm or less.
Description
本発明は、レドックス電池に関し、より詳しくは、高濃度系活物質液における導電率低下と粘性率及び溶液抵抗増大による電池内部抵抗の上昇を抑制して、充放電効率を向上できるレドックス電池に関する。
The present invention relates to a redox battery, and more particularly to a redox battery capable of improving charge and discharge efficiency by suppressing increase in battery internal resistance due to decrease in conductivity and viscosity and increase in solution resistance in a high concentration active material liquid.
大規模なエネルギー貯蔵源としてレドックス電池が知られている。活物質としてバナジウム電解液（活物質液ともいう）等を用いたレドックスフロー型二次電池は、室温で作動し、活物質が液体であるため、外部タンクに貯蔵でき、過充電、過放電耐久性にも優れている。そのため、電池の維持管理が容易で、長寿命である等の利点がある。
Redox battery is known as a large-scale energy storage source. Redox flow type secondary batteries that use vanadium electrolyte (also called active material liquid) as the active material operate at room temperature, and since the active material is liquid, it can be stored in an external tank, and can be overcharged and endured to overdischarge. Also excellent in properties. Therefore, there are advantages such as easy battery maintenance and long life.
バナジウムレドックスフロー電池の場合、正極活物質液にはバナジウム５価、４価系のレドックス対が用いられ、負極活物質液にはバナジウム２価、３価系のレドックス対が用いられている（特許文献１、２）。
In the case of a vanadium redox flow battery, a vanadium pentavalent and tetravalent redox pair is used for the positive electrode active material liquid, and a vanadium divalent and trivalent redox pair is used for the negative electrode active material liquid (patent). References 1, 2).
非特許文献１～３では、レドックスフロー電池において出力密度、エネルギー密度の増大を実現するために、活物質液中のバナジウム濃度を高濃度にする試みがなされている。
In Non-Patent Documents 1 to 3, an attempt is made to increase the vanadium concentration in the active material liquid in order to increase the output density and energy density in the redox flow battery.
非特許文献１、２は、正極活物質液として用いられ得る硫酸酸性の５価のバナジウム含有液について報告している。
Non-Patent Documents 1 and 2 report on a sulfuric acid pentavalent vanadium-containing liquid that can be used as a positive electrode active material liquid.
非特許文献１は、硫酸酸性の５価のバナジウム含有液について、バナジウム濃度が２．０Ｍを超えるとバナジウム塩の析出が生じやすくなることを明らかにしている。
Non-Patent Document 1 clarifies that precipitation of a vanadium salt is likely to occur when the vanadium concentration exceeds 2.0 M in a sulfuric acid pentavalent vanadium-containing liquid.
また、析出を生じた５価のバナジウム含有液に更に硫酸を添加し、加熱することによって一時的にこの沈殿を再溶解できるとしている。しかし、このようにして得られた正極活物質液は、サイクリックボルタングラムにおいて可逆性の低下が見られることから充放電における電圧効率の点で好ましくないとされている。この原因として、活物質液の著しい流動性の低下があり、非特許文献１は、このような高濃度の活物質系は、結果として実用性がないと結論付けている。
In addition, it is said that this precipitate can be temporarily redissolved by adding sulfuric acid to the pentavalent vanadium-containing liquid in which precipitation has occurred and heating. However, the positive electrode active material liquid obtained in this way is considered to be unfavorable in terms of voltage efficiency in charge and discharge because a reversible decrease is observed in the cyclic voltammogram. This is due to a significant decrease in fluidity of the active material liquid, and Non-Patent Document 1 concludes that such a high-concentration active material system is not practical as a result.
非特許文献２も、サイクリックボルタングラムに基づいて非特許文献１と同様の知見を報告している。
Non-Patent Document 2 also reports the same knowledge as Non-Patent Document 1 based on the cyclic voltammogram.
このように、硫酸酸性バナジウム化合物を含有する従来型の正極活物質液では、特にバナジウムを高い濃度で用いる場合において、十分な電極反応性と流動性を維持して、安定かつエネルギー効率のよい充放電を行なうことが困難であった。
As described above, the conventional positive electrode active material liquid containing an acidic vanadium sulfate compound maintains a sufficient electrode reactivity and fluidity, particularly when vanadium is used at a high concentration, and is stable and energy efficient. It was difficult to discharge.
一方、非特許文献３は、負極活物質液として用いられ得る２価、３価のバナジウム含有液について報告している。
On the other hand, Non-Patent Document 3 reports a divalent and trivalent vanadium-containing liquid that can be used as a negative electrode active material liquid.
非特許文献３は、負極活物質液中においてバナジウムが如何なる錯形態として存在するかを推定するために、クロノポテンシオメトリーにより、液中の２価、３価のバナジウムのそれぞれについて拡散係数を求め、実測した粘度から化学種のストークス半径を算出している。そして、算出されたストークス半径が、従来から２価、３価のバナジウムの化学種と考えられてきたアコ錯体、具体的にはＶ２＋（Ｈ２Ｏ）６あるいはＶ３＋（Ｈ２Ｏ）６のストークス半径と同程度であることを確認している。
Non-Patent Document 3 calculates the diffusion coefficient for each of divalent and trivalent vanadium in the liquid by chronopotentiometry in order to estimate what complex form vanadium exists in the negative electrode active material liquid. The Stokes radius of the chemical species is calculated from the actually measured viscosity. The calculated Stokes radius is an ako complex, specifically V 2+ (H 2 O) 6 or V 3+ (H 2 O) 6 , which has been conventionally considered as a chemical species of divalent and trivalent vanadium. It is confirmed that it is almost the same as the Stokes radius.
本発明者の知見によると、今まで、非特許文献３に示されるように、バナジウム２価、３価を含む負極液側は、水和イオンであって、他の配位子と錯体を作らないと考えられていた。しかし、１Ｍ乃至それ以下の希薄系と異なり１．５Ｍを越えるような系では、いわば固体的な性質を示してくるため、それに対応した考え方が重要である。単純に電荷の担い手がバナジウムというのではなく、むしろプロトンによる寄与が強くなり、これはＮＭＲスペクトルからも推定される。また、このような溶液はビンガム流体性を強く示す。結果として、ストークスの式を用いてイオン径を評価することはできない。
According to the knowledge of the present inventor, until now, as shown in Non-Patent Document 3, the negative electrode liquid side containing vanadium divalent and trivalent is a hydrated ion and forms a complex with another ligand. It was thought not. However, unlike a dilute system of 1M or less, a system exceeding 1.5M exhibits solid properties, so a corresponding idea is important. Vanadium is not simply the charge bearer, but rather a strong contribution from protons, which is also inferred from the NMR spectrum. In addition, such a solution strongly exhibits Bingham fluidity. As a result, the ion diameter cannot be evaluated using the Stokes equation.
また、非特許文献３は、「実用的なバナジウム濃度」として１．６Ｍの溶液を調製している。本発明者による試験結果においても、従来の負極活物質液において、バナジウムの析出を防止して、安定に充放電を継続できる濃度は１．５Ｍ～１．７Ｍ程度までであることが確かめられており、非特許文献３が記載する上記濃度は、従来の観点では妥当な値といえる。
Further, Non-Patent Document 3 prepares a 1.6 M solution as “practical vanadium concentration”. In the test results by the present inventors, it has been confirmed that the concentration of the conventional negative electrode active material liquid capable of preventing the deposition of vanadium and continuing the charge and discharge stably is about 1.5M to 1.7M. Therefore, the concentration described in Non-Patent Document 3 can be said to be a reasonable value from the conventional viewpoint.
硫酸酸性バナジウム化合物液を含有する従来型の負極活物質液もまた、特にバナジウムを高い濃度で用いる場合において、十分な電極反応性と流動性を維持することが困難であり、安定かつエネルギー効率のよい充放電を行ない得る電池にはならなかった。
A conventional negative electrode active material liquid containing an acidic vanadium sulfate compound liquid is also difficult to maintain sufficient electrode reactivity and fluidity, particularly when vanadium is used at a high concentration, and is stable and energy efficient. The battery could not be charged and discharged.
以上、非特許文献１～３を参照して従来のバナジウム濃度の高濃度化の試みについて説明した。なお、特許文献として、２．０Ｍを超えるバナジウム濃度を記載するものも多く見受けられるが、本発明者は、非特許文献を参照して上述したように、このような高濃度系ではバナジウムの析出を防止することが困難であり、十分な電極反応性及び流動性に劣ることを認識していた。この点については、実際に試験を行うことにより確認することができる。すでに実用化して稼動しているバナジウム系レドックスフロー型二次電池は、何れもバナジウム濃度として１．５～１．７Ｍ程度である。
The conventional attempts to increase the vanadium concentration have been described above with reference to Non-Patent Documents 1 to 3. Although many patent documents describe vanadium concentrations exceeding 2.0M, the present inventor, as described above with reference to the non-patent documents, precipitates vanadium in such a high concentration system. It has been recognized that it is difficult to prevent and inferior in sufficient electrode reactivity and fluidity. This can be confirmed by actually conducting a test. The vanadium redox flow type secondary batteries already in practical use and operating have a vanadium concentration of about 1.5 to 1.7M.
このように、従来の技術では、レドックス電池において、高濃度系活物質液における導電率低下と粘性率及び溶液抵抗増加による電池内部抵抗の上昇を抑制することが困難であり、充放電効率を向上する上で更なる改善の余地が見出される。
As described above, in the redox battery, it is difficult to suppress increase in battery internal resistance due to decrease in conductivity and viscosity and increase in solution resistance in a high-concentration active material liquid, thereby improving charge and discharge efficiency. There is room for further improvement.
そこで本発明の課題は、高濃度系活物質液における導電率低下と粘性率及び溶液抵抗増大による電池内部抵抗の上昇を抑制して、充放電効率を向上できるレドックス電池を提供することにある。
Therefore, an object of the present invention is to provide a redox battery capable of improving charge and discharge efficiency by suppressing increase in battery internal resistance due to decrease in conductivity and viscosity and increase in solution resistance in a high concentration active material liquid.
また本発明の他の課題は、以下の記載によって明らかとなる。
Further, other problems of the present invention will become apparent from the following description.
上記課題は、以下の各発明によって解決される。
The above problems are solved by the following inventions.
（請求項１）
正極活物質液を流通又は含浸させる正極と、
負極活物質液を流通又は含浸させる負極と、
前記正極と前記負極との間に設けられた隔膜とを備え、
前記正極活物質液及び前記負極活物質液は、それぞれ活物質濃度が１．８Ｍ以上であり、
前記隔膜は、イオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、且つ膜厚が１２０μｍ以下であることを特徴とするレドックス電池。
（請求項２）
前記正極及び前記負極は、それぞれ炭素繊維からなり、
前記炭素繊維の繊維径が１μｍ～１２μｍの範囲であり、かさ密度が０．５ｇ／ｍＬ～１．２ｇ／ｍＬの範囲であると共に、
前記隔膜面に垂直方向の前記正極及び前記負極の厚さが、前記正極活物質液及び前記負極活物質液を流通させて充放電を行う場合には、それぞれ３ｍｍ以下、前記正極活物質液及び前記負極活物質液を静止又は間欠的に流動させて充放電を行う場合には、それぞれ６ｍｍ以下であることを特徴とする請求項１記載のレドックス電池。
（請求項３）
前記正極活物質液及び前記負極活物質液は、それぞれ活物質としてバナジウムを含有し、バナジウム原子の含有量が１００ｇ／Ｌ以上であり、且つ硫酸根及び硫酸水素根としての硫黄原子の含有量が１２０ｇ／Ｌ以上であることを特徴とする請求項１又は２記載のレドックス電池。 (Claim 1)
A positive electrode for circulating or impregnating a positive electrode active material liquid;
A negative electrode that circulates or impregnates the negative electrode active material liquid;
A diaphragm provided between the positive electrode and the negative electrode,
Each of the positive electrode active material liquid and the negative electrode active material liquid has an active material concentration of 1.8 M or more,
The redox battery characterized in that the diaphragm has an ion exchange capacity of 2.0 (meq / g-dry ion exchange membrane) or more and a film thickness of 120 μm or less.
(Claim 2)
The positive electrode and the negative electrode are each made of carbon fiber,
The carbon fiber has a fiber diameter in the range of 1 μm to 12 μm, a bulk density in the range of 0.5 g / mL to 1.2 g / mL,
When the positive electrode and the negative electrode in the direction perpendicular to the diaphragm surface are charged and discharged by circulating the positive electrode active material liquid and the negative electrode active material liquid, the positive electrode active material liquid and 2. The redox battery according toclaim 1, wherein when the negative electrode active material liquid is charged or discharged while flowing statically or intermittently, each of the redox batteries is 6 mm or less.
(Claim 3)
Each of the positive electrode active material liquid and the negative electrode active material liquid contains vanadium as an active material, the content of vanadium atoms is 100 g / L or more, and the content of sulfur atoms as sulfate and hydrogen sulfate radicals It is 120 g / L or more, The redox battery of Claim 1 or 2 characterized by the above-mentioned.
正極活物質液を流通又は含浸させる正極と、
負極活物質液を流通又は含浸させる負極と、
前記正極と前記負極との間に設けられた隔膜とを備え、
前記正極活物質液及び前記負極活物質液は、それぞれ活物質濃度が１．８Ｍ以上であり、
前記隔膜は、イオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、且つ膜厚が１２０μｍ以下であることを特徴とするレドックス電池。
（請求項２）
前記正極及び前記負極は、それぞれ炭素繊維からなり、
前記炭素繊維の繊維径が１μｍ～１２μｍの範囲であり、かさ密度が０．５ｇ／ｍＬ～１．２ｇ／ｍＬの範囲であると共に、
前記隔膜面に垂直方向の前記正極及び前記負極の厚さが、前記正極活物質液及び前記負極活物質液を流通させて充放電を行う場合には、それぞれ３ｍｍ以下、前記正極活物質液及び前記負極活物質液を静止又は間欠的に流動させて充放電を行う場合には、それぞれ６ｍｍ以下であることを特徴とする請求項１記載のレドックス電池。
（請求項３）
前記正極活物質液及び前記負極活物質液は、それぞれ活物質としてバナジウムを含有し、バナジウム原子の含有量が１００ｇ／Ｌ以上であり、且つ硫酸根及び硫酸水素根としての硫黄原子の含有量が１２０ｇ／Ｌ以上であることを特徴とする請求項１又は２記載のレドックス電池。 (Claim 1)
A positive electrode for circulating or impregnating a positive electrode active material liquid;
A negative electrode that circulates or impregnates the negative electrode active material liquid;
A diaphragm provided between the positive electrode and the negative electrode,
Each of the positive electrode active material liquid and the negative electrode active material liquid has an active material concentration of 1.8 M or more,
The redox battery characterized in that the diaphragm has an ion exchange capacity of 2.0 (meq / g-dry ion exchange membrane) or more and a film thickness of 120 μm or less.
(Claim 2)
The positive electrode and the negative electrode are each made of carbon fiber,
The carbon fiber has a fiber diameter in the range of 1 μm to 12 μm, a bulk density in the range of 0.5 g / mL to 1.2 g / mL,
When the positive electrode and the negative electrode in the direction perpendicular to the diaphragm surface are charged and discharged by circulating the positive electrode active material liquid and the negative electrode active material liquid, the positive electrode active material liquid and 2. The redox battery according to
(Claim 3)
Each of the positive electrode active material liquid and the negative electrode active material liquid contains vanadium as an active material, the content of vanadium atoms is 100 g / L or more, and the content of sulfur atoms as sulfate and hydrogen sulfate radicals It is 120 g / L or more, The redox battery of
本発明によれば、高濃度系活物質液における導電率低下と粘性率及び溶液抵抗増大による電池内部抵抗の上昇を抑制して、充放電効率を向上できるレドックス電池を提供することができる。
According to the present invention, it is possible to provide a redox battery capable of improving charge and discharge efficiency by suppressing increase in battery internal resistance due to decrease in conductivity and viscosity and increase in solution resistance in a high concentration active material liquid.
以下に、本発明を実施するための形態について説明する。
Hereinafter, modes for carrying out the present invention will be described.
本発明のレドックス電池は、正極活物質液を流通又は含浸させる正極と、負極活物質液を流通又は含浸させる負極と、前記正極と前記負極との間に設けられた隔膜とを備える。
The redox battery of the present invention includes a positive electrode through which a positive electrode active material liquid is circulated or impregnated, a negative electrode through which a negative electrode active material liquid is circulated or impregnated, and a diaphragm provided between the positive electrode and the negative electrode.
本発明において、前記正極活物質液及び前記負極活物質液は、それぞれ活物質濃度が１．８Ｍ以上であり、前記隔膜は、イオン交換容量が２．０（ｍ当量／ｇ－乾燥イオン交換膜）以上であり、且つ膜厚が１２０μｍ以下である。
In the present invention, each of the positive electrode active material liquid and the negative electrode active material liquid has an active material concentration of 1.8 M or more, and the diaphragm has an ion exchange capacity of 2.0 (m equivalent / g-dry ion exchange membrane). ) And the film thickness is 120 μm or less.
これにより、レドックス電池において、高濃度系活物質液における導電率低下と粘性率及び溶液抵抗増加による電池内部抵抗の上昇を抑制して、充放電効率を向上できる効果が得られる。
Thereby, in the redox battery, an increase in the battery internal resistance due to a decrease in conductivity and viscosity and an increase in solution resistance in the high-concentration active material liquid can be suppressed, and the effect of improving the charge / discharge efficiency can be obtained.
以下に、図面を参照して本発明を実施するための形態について更に詳しく説明する。
Hereinafter, embodiments for carrying out the present invention will be described in more detail with reference to the drawings.
図１は、本発明のレドックス電池の一例を概念的に説明する図である。
FIG. 1 is a diagram conceptually illustrating an example of the redox battery of the present invention.
図１において、１は正極セル、２は負極セル、３は正極セル１と負極セル２とを分離する隔膜である。４はスペーサーであり、正極セル１、負極セル２のそれぞれに対応する間隙を形成している。
1, 1 is a positive electrode cell, 2 is a negative electrode cell, and 3 is a diaphragm that separates the positive electrode cell 1 and the negative electrode cell 2. A spacer 4 forms a gap corresponding to each of the positive electrode cell 1 and the negative electrode cell 2.
正極セル１内には正極１１が設けられ、負極セル２内には負極２１が設けられている。
A positive electrode 11 is provided in the positive electrode cell 1, and a negative electrode 21 is provided in the negative electrode cell 2.
正極１１及び負極２１は、それぞれ炭素繊維からなることが好ましい。かかる炭素繊維としては、セルロース、ポリアクリロニトリル（ＰＡＮ）、石油等から得られるピッチ、フェノール樹脂等を原料として焼成製造した略円形である炭素繊維を用いることができる。前記炭素繊維は、高晶質部（以下、グラファイト質炭素とも言う）と低晶質部を含み、平均直径は７μｍ～２０μｍの範囲であることが好ましい。
本発明における炭素繊維としては、かかる炭素繊維をそのまま用いるか、酸化性処理したものを好ましく用いることができる。本発明における炭素繊維としては、該炭素繊維を酸化性処理したものを特に好ましく用いることができる。 Thepositive electrode 11 and the negative electrode 21 are preferably made of carbon fiber. As such a carbon fiber, a substantially circular carbon fiber which is baked and produced from cellulose, polyacrylonitrile (PAN), pitch obtained from petroleum, etc., a phenol resin or the like as a raw material can be used. The carbon fiber preferably includes a high crystalline part (hereinafter also referred to as graphitic carbon) and a low crystalline part, and has an average diameter in the range of 7 μm to 20 μm.
As the carbon fiber in the present invention, such a carbon fiber can be used as it is or an oxidized treatment can be preferably used. As the carbon fiber in the present invention, those obtained by oxidizing the carbon fiber can be used particularly preferably.
本発明における炭素繊維としては、かかる炭素繊維をそのまま用いるか、酸化性処理したものを好ましく用いることができる。本発明における炭素繊維としては、該炭素繊維を酸化性処理したものを特に好ましく用いることができる。 The
As the carbon fiber in the present invention, such a carbon fiber can be used as it is or an oxidized treatment can be preferably used. As the carbon fiber in the present invention, those obtained by oxidizing the carbon fiber can be used particularly preferably.
前記酸化性処理は格別限定されないが、例えば湿式処理法や乾式処理法を用いることができる。
Although the oxidizing treatment is not particularly limited, for example, a wet treatment method or a dry treatment method can be used.
湿式処理法としては、例えば、電解酸化処理の他、過酸化ナトリウムや過酸化水素などを含有する溶液あるいは硝酸や過硫酸等の酸を含有する酸化性の酸溶液中での加熱処理等を好ましく用いることができる。ここで、電解酸化処理は、高晶質部と低晶質部を含む炭素繊維に対する見掛けの電流密度や通電時間を任意に選択でき、処理を調整しやすい点で優れた方法と言える。
As the wet treatment method, for example, in addition to electrolytic oxidation treatment, heat treatment in a solution containing sodium peroxide or hydrogen peroxide or an oxidizing acid solution containing an acid such as nitric acid or persulfuric acid is preferable. Can be used. Here, the electrolytic oxidation treatment can be said to be an excellent method in that the apparent current density and energization time for the carbon fiber including the high crystalline portion and the low crystalline portion can be arbitrarily selected and the treatment can be easily adjusted.
乾式処理法としては、例えば、炉内に若干の空気を混合するなどの酸化性雰囲気中での加熱処理（例えば空気を０．１％程度混入して窒素雰囲気下での酸化性処理を含む）や、水蒸気とアルミニウム化合物等のエッチング剤とを混合した雰囲気中での加熱処理等を好ましく用いることができる。
As a dry processing method, for example, heat treatment in an oxidizing atmosphere such as mixing some air in the furnace (for example, including an oxidizing treatment in a nitrogen atmosphere by mixing about 0.1% of air) Alternatively, heat treatment in an atmosphere in which water vapor and an etching agent such as an aluminum compound are mixed can be preferably used.
焼成によって得られた、高晶質部と低晶質部を含む炭素繊維を酸化性処理することにより、炭素繊維中のグラファイト化されていない低晶質部の部分は、耐酸化性が低いために選択的に酸化分解され、耐酸化性の高い高晶質部の部分は酸化されにくく残存する。その結果、炭素繊維の繊維径が５μｍ以下程度と細くなり、同時に、炭素繊維におけるグラファイト化度の高い高晶質部の割合を高めることができる。
By oxidizing the carbon fiber containing the high crystalline part and the low crystalline part obtained by firing, the non-graphitized low crystalline part in the carbon fiber has low oxidation resistance. The portion of the highly crystalline portion that is selectively oxidized and decomposed and has high oxidation resistance remains difficult to be oxidized. As a result, the fiber diameter of the carbon fiber is reduced to about 5 μm or less, and at the same time, the ratio of the highly crystalline part having a high degree of graphitization in the carbon fiber can be increased.
酸化性処理した炭素繊維は、繊維径が細いことによって物質移動性が向上し、被電解物質の拡散がより多次元的（例えば２次元から２．５次元拡散）となり、更に、表面がグラファイト質炭素になるので、電極反応性（電荷移動反応性）も向上する。これらの相乗的な作用により、正極１１及び負極２１は、被電解物質に対して高い電流密度をもって電解できる効果を奏するため、酸化性処理した炭素繊維がより好ましい。
Oxidation-treated carbon fibers have improved mass mobility due to the small fiber diameter, the diffusion of the electrolyzed material becomes more multi-dimensional (for example, from 2D to 2.5D diffusion), and the surface is graphitic. Since it becomes carbon, electrode reactivity (charge transfer reactivity) is also improved. Because of these synergistic actions, the positive electrode 11 and the negative electrode 21 have an effect of being able to perform electrolysis with a high current density with respect to the substance to be electrolyzed, and therefore, oxidized carbon fibers are more preferable.
上記のような観点から、炭素繊維の繊維径が１μｍ～１２μｍの範囲であり、かさ密度が０．５ｇ／ｍＬ～１．２ｇ／ｍＬの範囲であることが好ましい。これにより、電極による活物質の捕捉性を好適に発揮させると共に、電池内部抵抗の上昇を好適に抑制できる効果が得られる。
From the above viewpoint, it is preferable that the fiber diameter of the carbon fiber is in the range of 1 μm to 12 μm and the bulk density is in the range of 0.5 g / mL to 1.2 g / mL. As a result, it is possible to obtain the effect that the active material capturing ability by the electrode can be suitably exhibited and the increase in battery internal resistance can be suitably suppressed.
ここで、炭素繊維の繊維径は、走査型電子顕微鏡（ＳＥＭ）を用いて測定することができ、繊維断面が略円形でない場合は、該繊維における最も短い径を繊維径とする。炭素繊維のかさ密度は、無荷重時の見掛けの体積と重さから算出された値である。
Here, the fiber diameter of the carbon fiber can be measured using a scanning electron microscope (SEM). When the fiber cross section is not substantially circular, the shortest diameter of the fiber is defined as the fiber diameter. The bulk density of the carbon fiber is a value calculated from the apparent volume and weight when there is no load.
また、正極１１及び負極２１の厚さが、正極活物質液及び前記負極活物質液を流通させて充放電を行う場合には、それぞれ３ｍｍ以下、好ましくは２ｍｍ以下、より好ましくは１ｍｍであり、前記正極活物質液及び前記負極活物質液を静止又は間欠的に流動させて充放電を行う場合には、それぞれ６ｍｍ以下、好ましくは５ｍｍ以下であることが好ましい。活物質液静止又は間欠的流動型電池の場合は、必要な充放電容量を確保するために、セル面積抵抗率の低減をある程度犠牲にする必要があるため、フロー型電池の場合に比べて厚い電極を用いることが好ましい。ここでいう厚さは、隔膜３面に垂直方向の厚さを指す。
Further, when the positive electrode 11 and the negative electrode 21 are charged and discharged by circulating the positive electrode active material liquid and the negative electrode active material liquid, the thickness is 3 mm or less, preferably 2 mm or less, more preferably 1 mm, When charging / discharging by making the said positive electrode active material liquid and the said negative electrode active material liquid flow statically or intermittently, it is 6 mm or less, respectively, Preferably it is 5 mm or less. In the case of an active material liquid stationary or intermittent flow type battery, it is necessary to sacrifice some reduction in cell area resistivity in order to ensure the necessary charge / discharge capacity, so it is thicker than in the case of a flow type battery. It is preferable to use an electrode. The thickness here refers to the thickness in the direction perpendicular to the surface of the diaphragm 3.
本発明者は、当初、正極１１及び負極２１の厚さを、フロー型電池の場合にそれぞれ３ｍｍ以下、静止又は間欠的流動型電池の場合にそれぞれ６ｍｍ以下にまで薄くすることは、電極による活物質の捕捉性が抑制されてしまい、好ましくないものと考えた。ところが、実際に試験を行い鋭意検討した結果、正極１１及び負極２１の厚さを、フロー型電池の場合にはそれぞれ３ｍｍ以下、静止又は間欠的流動電池の場合にはそれぞれ６ｍｍ以下にまで薄くすることにより、活物質濃度が１．８Ｍ以上である高濃度活物質液を用いる場合において、導電性低下を好適に抑制することができ、電池内部抵抗の上昇を防止できることを見出した。電極による活物質の捕捉性についても、活物質濃度が１．８Ｍ以上である高濃度活物質液を用いることにより好適に保持できることがわかった。特に炭素繊維の繊維径が５μｍ以下である場合には、正極１１及び負極２１の厚さを、フロー型電池の場合にはそれぞれ３ｍｍ以下、静止又は間欠的流動電池の場合にはそれぞれ６ｍｍ以下にすることの効果が顕著になる。
The inventor initially reduced the thickness of the positive electrode 11 and the negative electrode 21 to 3 mm or less in the case of a flow type battery and to 6 mm or less in the case of a static or intermittent flow type battery, respectively. The trapping property of the substance was suppressed, which was considered undesirable. However, as a result of actual tests and intensive studies, the thickness of the positive electrode 11 and the negative electrode 21 is reduced to 3 mm or less in the case of a flow type battery and to 6 mm or less in the case of a stationary or intermittent flow battery, respectively. Thus, it has been found that in the case of using a high-concentration active material liquid having an active material concentration of 1.8 M or more, a decrease in conductivity can be suitably suppressed and an increase in battery internal resistance can be prevented. It was also found that the active material scavenging ability by the electrode can be suitably maintained by using a high concentration active material liquid having an active material concentration of 1.8 M or more. In particular, when the fiber diameter of the carbon fiber is 5 μm or less, the thickness of the positive electrode 11 and the negative electrode 21 is 3 mm or less for a flow type battery, and 6 mm or less for a stationary or intermittent flow battery, respectively. The effect of doing becomes remarkable.
正極セル１には、該正極セル１内に正極活物質液を流入するための流入口１２と、該正極セル１内の正極活物質液を流出するための流出口１３とが設けられている。
The positive electrode cell 1 is provided with an inlet 12 for flowing the positive electrode active material liquid into the positive electrode cell 1 and an outlet 13 for flowing the positive electrode active material liquid in the positive electrode cell 1. .
正極活物質液タンク１４内に貯留された正極活物質液は、ポンプ１５の駆動によって、流入口１２に接続された流入管１６を介して、正極セル１内に流入するように構成されている。また、流出口１３から流出された正極活物質液は、流出口１３に接続された流出管１７を介して正極活物質液タンク１４内に返送されるように構成されている。このようにして、正極活物質液タンク１４から正極セル１内に正極活物質液を循環供給する循環系が構成されている。
The positive electrode active material liquid stored in the positive electrode active material liquid tank 14 is configured to flow into the positive electrode cell 1 through the inflow pipe 16 connected to the inlet 12 by driving the pump 15. . Further, the positive electrode active material liquid that has flowed out from the outlet 13 is returned to the positive electrode active material liquid tank 14 through an outlet pipe 17 connected to the outlet 13. In this way, a circulation system for circulating and supplying the positive electrode active material liquid from the positive electrode active material liquid tank 14 into the positive electrode cell 1 is configured.
負極セル２には、該負極セル２内に負極活物質液を流入するための流入口２２と、該負極セル２内の負極活物質液を流出するための流出口２３とが設けられている。
The negative electrode cell 2 is provided with an inlet 22 for flowing the negative electrode active material liquid into the negative electrode cell 2 and an outlet 23 for flowing the negative electrode active material liquid in the negative electrode cell 2. .
負極活物質液タンク２４内に貯留された負極活物質液は、ポンプ２５の駆動によって、流入口２２に接続された流入管２６を介して、負極セル２内に流入するように構成されている。また、流出口２３から流出された負極活物質液は、流出口２３に接続された流出管２７を介して負極活物質液タンク２４内に返送されるように構成されている。このようにして、負極活物質液タンク２４から負極セル２内に負極活物質液を循環供給する循環系が構成されている。
The negative electrode active material liquid stored in the negative electrode active material liquid tank 24 is configured to flow into the negative electrode cell 2 through the inflow pipe 26 connected to the inflow port 22 when the pump 25 is driven. . The negative electrode active material liquid that has flowed out of the outlet 23 is returned to the negative electrode active material liquid tank 24 through an outlet pipe 27 connected to the outlet 23. In this way, a circulation system for circulating and supplying the negative electrode active material liquid from the negative electrode active material liquid tank 24 into the negative electrode cell 2 is configured.
図示の例では、正極１１及び負極２１のそれぞれに接触するように導電性シート５、５が設けられ、導電性シート５、５の外側から押え板６、６によってセル全体を挟持している。正極１１及び負極２１は、それぞれ導電性シート５、５を介して外部回路に接続することができる。図示しないが、導電性シート５、５としてバイポーラープレート等を用いることによって、正極セル及び負極セルからなるセルユニットを複数積層した積層構造を構成することも好ましいことである。
In the illustrated example, conductive sheets 5 and 5 are provided so as to be in contact with each of the positive electrode 11 and the negative electrode 21, and the entire cell is sandwiched by the pressing plates 6 and 6 from the outside of the conductive sheets 5 and 5. The positive electrode 11 and the negative electrode 21 can be connected to an external circuit via the conductive sheets 5 and 5, respectively. Although not shown, it is also preferable to form a laminated structure in which a plurality of cell units each composed of a positive electrode cell and a negative electrode cell are laminated by using a bipolar plate or the like as the conductive sheets 5 and 5.
レドックス電池は、正極セル１及び負極セル２にそれぞれ負極活物質液及び正極活物質液を循環供給して、両極における活物質液中の活物質の電極反応（酸化還元反応）に伴って充放電を行う。
The redox battery circulates and supplies a negative electrode active material liquid and a positive electrode active material liquid to the positive electrode cell 1 and the negative electrode cell 2, respectively, and is charged and discharged with an electrode reaction (oxidation-reduction reaction) of the active material in the active material liquid at both electrodes. I do.
本発明において、正極活物質液及び負極活物質液は、それぞれ活物質濃度が１．８Ｍ以上である。硫酸酸性のバナジウム２価、３価、及び４価、５価の化合物を含有する活物質液に限らず、鉄やクロム、チタン系等の活物質液においても、それらの濃度が１．８Ｍを超えると、電極面への物質移動性が著しく低下してくる。
In the present invention, each of the positive electrode active material liquid and the negative electrode active material liquid has an active material concentration of 1.8 M or more. Not only the active material liquid containing sulfuric acid acidic vanadium divalent, trivalent, tetravalent, and pentavalent compounds, but also the active material liquid of iron, chromium, titanium, etc. has a concentration of 1.8M. When it exceeds, the mass mobility to an electrode surface will fall remarkably.
正極活物質液及び負極活物質液における、各活物質をバナジウムとした場合、レドックス電池の充電時及び放電時の電極反応は、それぞれ下記のように表される。
（充電時の電極反応）
正極反応：ＶＯ２＋（４価）＋Ｈ２Ｏ → ＶＯ２ ＋（５価）＋２Ｈ＋＋ｅ－
負極反応：Ｖ３＋（３価）＋ｅ－ → Ｖ２＋（２価）
（放電時の電極反応）
正極反応：ＶＯ２ ＋（５価）＋２Ｈ＋＋ｅ－ → ＶＯ２＋（４価）＋Ｈ２Ｏ
負極反応：Ｖ２＋（２価） → Ｖ３＋（３価）＋ｅ－ When each active material in the positive electrode active material liquid and the negative electrode active material liquid is vanadium, the electrode reactions at the time of charging and discharging of the redox battery are respectively expressed as follows.
(Electrode reaction during charging)
Positive reaction: VO 2+ (4-valent) + H 2 O → VO 2 + (5 valence) + 2H + + e -
Negative electrode reaction: V 3+ (trivalent) + e − → V 2+ (divalent)
(Electrode reaction during discharge)
Positive reaction: VO 2 + (5 valence) + 2H + + e - →VO 2+ (4 -valent) + H 2 O
Negative electrode reaction: V 2+ (divalent) → V 3+ (trivalent) + e −
（充電時の電極反応）
正極反応：ＶＯ２＋（４価）＋Ｈ２Ｏ → ＶＯ２ ＋（５価）＋２Ｈ＋＋ｅ－
負極反応：Ｖ３＋（３価）＋ｅ－ → Ｖ２＋（２価）
（放電時の電極反応）
正極反応：ＶＯ２ ＋（５価）＋２Ｈ＋＋ｅ－ → ＶＯ２＋（４価）＋Ｈ２Ｏ
負極反応：Ｖ２＋（２価） → Ｖ３＋（３価）＋ｅ－ When each active material in the positive electrode active material liquid and the negative electrode active material liquid is vanadium, the electrode reactions at the time of charging and discharging of the redox battery are respectively expressed as follows.
(Electrode reaction during charging)
Positive reaction: VO 2+ (4-valent) + H 2 O → VO 2 + (5 valence) + 2H + + e -
Negative electrode reaction: V 3+ (trivalent) + e − → V 2+ (divalent)
(Electrode reaction during discharge)
Positive reaction: VO 2 + (5 valence) + 2H + + e - →
Negative electrode reaction: V 2+ (divalent) → V 3+ (trivalent) + e −
正極活物質液及び負極活物質液が、それぞれ活物質としてバナジウムを含有する場合は、バナジウム原子の含有量が１００ｇ／Ｌ以上であることが好ましく、より好ましくは、１３０ｇ／Ｌ以上である。硫酸根及び硫酸水素根としての硫黄原子の含有量は１２０ｇ／Ｌ以上であることが好ましく、より好ましくは１８０ｇ／Ｌである。これにより、活物質であるバナジウムの析出、沈殿が防止される効果が得られる。なお、バナジウム原子の含有量は、感光法、吸光法等一般的な定量方法により測定できる。また、硫酸根及び硫酸水素根としての硫黄原子の含有量も同様の定量方法により測定できる。
When each of the positive electrode active material liquid and the negative electrode active material liquid contains vanadium as an active material, the vanadium atom content is preferably 100 g / L or more, and more preferably 130 g / L or more. The content of sulfur atoms as sulfate and hydrogen sulfate radicals is preferably 120 g / L or more, more preferably 180 g / L. Thereby, the effect that precipitation and precipitation of vanadium which is an active material is prevented is obtained. The vanadium atom content can be measured by a general quantitative method such as a photosensitivity method or an absorption method. The content of sulfur atoms as sulfate radicals and hydrogen sulfate radicals can also be measured by the same quantitative method.
隔膜３は、充電時及び放電時において、電池内部の電荷キャリアであるプロトンの透過を許容すると共に、自己放電抑制のために活物質の透過を防止する役割を担う。
The diaphragm 3 plays a role of allowing permeation of protons that are charge carriers inside the battery during charging and discharging, and preventing permeation of the active material in order to suppress self-discharge.
本発明において、隔膜３は、イオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、且つ膜厚が１２０μｍ以下、好ましくは８０μｍ以下、より好ましくは５０μｍ以下である。２０μｍが引張強度上の薄さの限界である。
In the present invention, the diaphragm 3 has an ion exchange capacity of 2.0 (meq / g-dry ion exchange membrane) or more and a film thickness of 120 μm or less, preferably 80 μm or less, more preferably 50 μm or less. 20 μm is the limit of thinness on the tensile strength.
ここで、イオン交換容量（ｍｅｑ／ｇ－乾燥イオン交換膜）は、乾燥させた隔膜（イオン交換膜）の単位重量（ｇ）当たりに含まれるイオン交換基の電気当量数（ｍｅｑ）を意味する。
Here, the ion exchange capacity (meq / g-dry ion exchange membrane) means the number of electric equivalents (meq) of ion exchange groups contained per unit weight (g) of the dried diaphragm (ion exchange membrane). .
本発明では、正極活物質液及び負極活物質液の活物質濃度がそれぞれ１．８Ｍ以上という高濃度であることと、上述した特定のイオン交換容量及び膜厚を有する隔膜３を用いることとによって、これらの相乗的な作用として、レドックス電池において、高濃度系活物質液における導電率低下と粘性率及び溶液抵抗増加による電池内部抵抗の上昇を抑制して、充放電効率を向上できる効果が得られる。
In the present invention, the active material concentration of each of the positive electrode active material liquid and the negative electrode active material liquid is as high as 1.8 M or more, and by using the diaphragm 3 having the specific ion exchange capacity and film thickness described above. As a synergistic action of these, in redox batteries, the effect of improving the charge / discharge efficiency by suppressing the decrease in conductivity and the increase in battery internal resistance due to increase in viscosity and solution resistance in high-concentration active material liquid is obtained. It is done.
隔膜３の膜厚の下限は格別限定されないが、十分な強度を得る観点では、１０μｍ以上であることが好ましい。
The lower limit of the thickness of the diaphragm 3 is not particularly limited, but is preferably 10 μm or more from the viewpoint of obtaining sufficient strength.
膜厚が１２０μｍ以下である隔膜は、市販品として入手可能であり、例えばデュポン社製「ナフィオン（登録商標）Ｎ２１２」（膜厚５７μｍ（０．０５７ｍｍ））、「ナフィオン（登録商標）Ｎ２１１」（膜厚２５μｍ（０．０２５ｍｍ））等のイオン交換膜等が挙げられる。
A diaphragm having a film thickness of 120 μm or less is commercially available. For example, “Nafion (registered trademark) N212” (film thickness 57 μm (0.057 mm)), “Nafion (registered trademark) N211” (manufactured by DuPont) Examples thereof include an ion exchange membrane having a film thickness of 25 μm (0.025 mm).
図１に示したレドックス電池では、シート状に形成された電極（正極１１及び負極２１）の電極面方向と平行に活物質液を透過させる「flow by」方式を用いたが、これに限定されるものではない。シート状に形成された電極に対して液を横断させるように透過させる「flow through」方式を用いることも好ましいことである。
In the redox battery shown in FIG. 1, the “flow」 by ”method that allows the active material liquid to permeate in parallel with the electrode surface direction of the sheet-like electrodes (the positive electrode 11 and the negative electrode 21) is used. It is not something. It is also preferable to use a “flow-through” system that allows the liquid to pass across the sheet-shaped electrode.
「flow through」方式を用いたレドックス電池の一例について、図２を参照して説明する。図２において、図１と同符号は同構成を指し、図１を参酌してした説明が援用される。
An example of a redox battery using the “flow through” method will be described with reference to FIG. In FIG. 2, the same reference numerals as those in FIG. 1 denote the same components, and the explanation with reference to FIG. 1 is incorporated.
図２に示すレドックス電池において、正極１１はシート状に形成されており、支持体である導電性シート１１ａ、１１ｂ間に挟持されて電極ユニット１０を構成している。
In the redox battery shown in FIG. 2, the positive electrode 11 is formed in a sheet shape, and is sandwiched between conductive sheets 11a and 11b, which are supports, to constitute the electrode unit 10.
図３の展開図に示すように、電極ユニット１０は、導電性シート１１ａ、１１ｂと、該導電性シート１１ａ、１１ｂ間に挟持されるシート状の正極１１と、により構成されている。
As shown in the developed view of FIG. 3, the electrode unit 10 is composed of conductive sheets 11a and 11b and a sheet-like positive electrode 11 sandwiched between the conductive sheets 11a and 11b.
導電性シート１１ａ、１１ｂには、互いに対向する位置に孔１１０ａ、１１０ｂが設けられており、これらの孔１１０ａ、１１０ｂから正極１１を露出するように構成されている。ここでは、各導電性シート１１ａ、１１ｂに、それぞれ１つの孔１１０ａ、１１０ｂを設ける場合について示しているが、複数の孔を設けることによって、複数の部位で正極１１を露出させることも好ましいことである。
The conductive sheets 11a and 11b are provided with holes 110a and 110b at positions facing each other, and the positive electrode 11 is exposed from the holes 110a and 110b. Here, the case where one hole 110a, 110b is provided in each of the conductive sheets 11a, 11b is shown, but it is also preferable to expose the positive electrode 11 at a plurality of portions by providing a plurality of holes. is there.
導電性シート１１ａ、１１ｂ間にはスペーサー１１ｃを介在させている。スペーサー１１ｃを設けることによって、正極１１を所定の厚さで保持でき、更に正極１１を構成する炭素繊維が活物質液の透過等によって偏ったりバラバラになったりすることを防止できる。
A spacer 11c is interposed between the conductive sheets 11a and 11b. By providing the spacer 11c, the positive electrode 11 can be held at a predetermined thickness, and further, the carbon fibers constituting the positive electrode 11 can be prevented from being biased or falling apart due to permeation of the active material liquid or the like.
正極セル１は、電極ユニット１０によって、流入口１２が設けられた流入側マニホールド１ａと、流出口１３が設けられた流出側マニホールド１ｂとに分割されている。
The positive electrode cell 1 is divided by an electrode unit 10 into an inflow side manifold 1 a provided with an inflow port 12 and an outflow side manifold 1 b provided with an outflow port 13.
流入口１２からの正極活物質液は、まず流入側マニホールド１ａに流入した後、電極ユニット１０が備えるシート状の正極１１を横断するように透過し、流出側マニホールド１ｂに排出される。流出側マニホールド１ｂに排出された正極活物質液は、流出口１３から流出される。
The positive electrode active material liquid from the inlet 12 first flows into the inflow side manifold 1a, then permeates across the sheet-like positive electrode 11 included in the electrode unit 10, and is discharged to the outflow side manifold 1b. The positive electrode active material liquid discharged to the outflow side manifold 1 b flows out from the outflow port 13.
負極２１についても同様の構成とすることができる。即ち、負極２１用の電極ユニット２０は、導電性シート２１ａ、２１ｂと、該導電性シート２１ａ、２１ｂ間に挟持されるシート状の負極２１と、スペーサー２１ｃとにより構成することができる。
The negative electrode 21 can have the same configuration. That is, the electrode unit 20 for the negative electrode 21 can be composed of conductive sheets 21a and 21b, a sheet-like negative electrode 21 sandwiched between the conductive sheets 21a and 21b, and a spacer 21c.
負極セル２は、電極ユニット２０によって、流入口２２が設けられた流入側マニホールド２ａと、流出口２３が設けられた流出側マニホールド２ｂとに分割されている。
The negative electrode cell 2 is divided by the electrode unit 20 into an inflow side manifold 2 a provided with an inflow port 22 and an outflow side manifold 2 b provided with an outflow port 23.
流入口２２からの負極活物質液は、まず流入側マニホールド２ａに流入した後、電極ユニット２０が備えるシート状の負極２１を横断するように透過し、流出側マニホールド２ｂに排出される。流出側マニホールド２ｂに排出された負極活物質液は、流出口２３から流出される。
The negative electrode active material liquid from the inlet 22 first flows into the inflow side manifold 2a, then permeates across the sheet-like negative electrode 21 provided in the electrode unit 20, and is discharged to the outflow side manifold 2b. The negative electrode active material liquid discharged to the outflow side manifold 2 b flows out from the outflow port 23.
「flow through」方式のレドックス電池においても、正極セル１及び負極セル２にそれぞれ負極活物質液及び正極活物質液を循環供給して、両極における活物質液中の活物質の電極反応（酸化還元反応）に伴って充放電を行う。レドックス電池の充電時及び放電時の電極反応式は、「flow by」方式と同様である。
Also in the “flow through” type redox battery, the negative electrode active material liquid and the positive electrode active material liquid are circulated and supplied to the positive electrode cell 1 and the negative electrode cell 2 respectively, and the electrode reaction (oxidation reduction) of the active material in the active material liquid at both electrodes Charge / discharge is performed with the reaction). The electrode reaction equation at the time of charging and discharging of the redox battery is the same as that of the “flow-by” method.
「flow through」方式のレドックス電池においても、活物質濃度が１．８Ｍ以上である正極活物質液及び前記負極活物質液を用い、且つイオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、膜厚が１２０μｍ以下である隔膜を用いることによって、「flow by」方式と同様に、本発明の効果が奏される。
The “flow-through” type redox battery also uses a positive electrode active material liquid having an active material concentration of 1.8 M or more and the negative electrode active material liquid, and has an ion exchange capacity of 2.0 (meq / g-dry ion exchange). By using a diaphragm having a film thickness of 120 μm or less, the effect of the present invention can be obtained in the same manner as the “flow-by” method.
以上の説明では、正極活物質液を正極に流通させ、負極活物質液を負極に流通させるレドックス電池（レドックスフロー電池ともいう）について主に示したが、これに限定されるものではない。
In the above description, a redox battery (also referred to as a redox flow battery) in which the positive electrode active material liquid is circulated to the positive electrode and the negative electrode active material liquid is circulated to the negative electrode is mainly shown, but the present invention is not limited to this.
本発明では、レドックス電池の充放電時において、活物質液は必ずしも流動状態にある必要はなく、キャパシタのように活物質液を静止させた状態にしてもよいし、あるいは間欠的に流動させるようにしてもよい。即ち、充放電時において、正極活物質液及び負極活物質液を、それぞれ正極及び負極に流通させる場合に限定されず、それぞれ正極及び負極に含浸させていればよい。活物質液を静止又は間欠的に流動させた状態で充放電を行うレドックス電池においても、活物質濃度が１．８Ｍ以上である正極活物質液及び前記負極活物質液を用い、且つイオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、膜厚が１２０μｍ以下である隔膜を用いることによって、活物質を電極に流通させる場合と同様に、本発明の効果が奏される。
In the present invention, at the time of charging / discharging of the redox battery, the active material liquid does not necessarily need to be in a fluid state, and the active material liquid may be in a stationary state like a capacitor, or may be allowed to flow intermittently. It may be. That is, it is not limited to the case where the positive electrode active material liquid and the negative electrode active material liquid are circulated through the positive electrode and the negative electrode, respectively, and the positive electrode and the negative electrode may be impregnated. Even in a redox battery that charges and discharges in a state where the active material liquid flows statically or intermittently, the positive electrode active material liquid having an active material concentration of 1.8 M or more and the negative electrode active material liquid are used, and the ion exchange capacity By using a diaphragm having a thickness of 2.0 (meq / g-dry ion exchange membrane) or more and a film thickness of 120 μm or less, the effect of the present invention is exhibited as in the case where the active material is passed through the electrode. The
以下に、本発明の実施例について説明するが、本発明はかかる実施例により限定されない。
Hereinafter, examples of the present invention will be described, but the present invention is not limited to the examples.
（実施例１）
図２に示したフロースルー型レドックス電池において、膜厚が５７（μｍ）であり、且つイオン交換容量が２．５（ｍｅｑ／ｇ－乾燥イオン交換膜）であるフッ素系イオン交換膜を用い、以下の条件で充放電試験を実施した。 Example 1
In the flow-through redox battery shown in FIG. 2, a fluorine-based ion exchange membrane having a film thickness of 57 (μm) and an ion exchange capacity of 2.5 (meq / g-dry ion exchange membrane) is used. The charge / discharge test was conducted under the following conditions.
図２に示したフロースルー型レドックス電池において、膜厚が５７（μｍ）であり、且つイオン交換容量が２．５（ｍｅｑ／ｇ－乾燥イオン交換膜）であるフッ素系イオン交換膜を用い、以下の条件で充放電試験を実施した。 Example 1
In the flow-through redox battery shown in FIG. 2, a fluorine-based ion exchange membrane having a film thickness of 57 (μm) and an ion exchange capacity of 2.5 (meq / g-dry ion exchange membrane) is used. The charge / discharge test was conducted under the following conditions.
＜正極活物質液及び負極活物質液＞
・正極活物質液
活物質濃度：２．５Ｍバナジウム（４価、５価）
硫酸根及び硫酸水素根としての硫黄原子の含有量：１８０ｇ／Ｌ
・負極活物質液
活物質濃度：２．５Ｍバナジウム（２価、３価）
硫酸根及び硫酸水素根としての硫黄原子の含有量：１８０ｇ／Ｌ <Positive electrode active material liquid and negative electrode active material liquid>
-Positive electrode active material liquid Active material concentration: 2.5M vanadium (tetravalent, pentavalent)
Sulfur atom content as sulfate and hydrogen sulfate radicals: 180 g / L
・ Negative electrode active material liquid Active material concentration: 2.5M vanadium (divalent, trivalent)
Sulfur atom content as sulfate and hydrogen sulfate radicals: 180 g / L
・正極活物質液
活物質濃度：２．５Ｍバナジウム（４価、５価）
硫酸根及び硫酸水素根としての硫黄原子の含有量：１８０ｇ／Ｌ
・負極活物質液
活物質濃度：２．５Ｍバナジウム（２価、３価）
硫酸根及び硫酸水素根としての硫黄原子の含有量：１８０ｇ／Ｌ <Positive electrode active material liquid and negative electrode active material liquid>
-Positive electrode active material liquid Active material concentration: 2.5M vanadium (tetravalent, pentavalent)
Sulfur atom content as sulfate and hydrogen sulfate radicals: 180 g / L
・ Negative electrode active material liquid Active material concentration: 2.5M vanadium (divalent, trivalent)
Sulfur atom content as sulfate and hydrogen sulfate radicals: 180 g / L
＜正極及び負極＞
・材質及び処理：炭素繊維フェルト（ＰＡＮ系、空気を０．１％程度混入して窒素雰囲気、１５００℃にて焼成）
・炭素繊維の繊維径：５～１０μｍ
・かさ密度：１．０ｇ／ｍＬ
・厚さ：１ｍｍ <Positive electrode and negative electrode>
・ Material and treatment: Carbon fiber felt (PAN-based, mixed with about 0.1% of air, nitrogen atmosphere, fired at 1500 ° C)
-Fiber diameter of carbon fiber: 5-10μm
-Bulk density: 1.0 g / mL
・ Thickness: 1mm
・材質及び処理：炭素繊維フェルト（ＰＡＮ系、空気を０．１％程度混入して窒素雰囲気、１５００℃にて焼成）
・炭素繊維の繊維径：５～１０μｍ
・かさ密度：１．０ｇ／ｍＬ
・厚さ：１ｍｍ <Positive electrode and negative electrode>
・ Material and treatment: Carbon fiber felt (PAN-based, mixed with about 0.1% of air, nitrogen atmosphere, fired at 1500 ° C)
-Fiber diameter of carbon fiber: 5-10μm
-Bulk density: 1.0 g / mL
・ Thickness: 1mm
（実施例２）
実施例１において、前記イオン交換膜に代えて、膜厚が２５（μｍ）であり、且つイオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）であるフッ素系イオン交換膜を用いたこと以外は実施例１と同様にして充放電試験を実施した。 (Example 2)
In Example 1, instead of the ion exchange membrane, a fluorine ion exchange membrane having a film thickness of 25 (μm) and an ion exchange capacity of 2.0 (meq / g-dry ion exchange membrane) is used. A charge / discharge test was carried out in the same manner as in Example 1 except that.
実施例１において、前記イオン交換膜に代えて、膜厚が２５（μｍ）であり、且つイオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）であるフッ素系イオン交換膜を用いたこと以外は実施例１と同様にして充放電試験を実施した。 (Example 2)
In Example 1, instead of the ion exchange membrane, a fluorine ion exchange membrane having a film thickness of 25 (μm) and an ion exchange capacity of 2.0 (meq / g-dry ion exchange membrane) is used. A charge / discharge test was carried out in the same manner as in Example 1 except that.
（比較例１）
実施例１において、前記イオン交換膜に代えて、膜厚が１５０（μｍ）であり、且つイオン交換容量が２．８（ｍｅｑ／ｇ－乾燥イオン交換膜）であるポリエチレンスルホン酸系イオン交換膜を用いたこと以外は実施例１と同様にして充放電試験を実施した。 (Comparative Example 1)
In Example 1, in place of the ion exchange membrane, a polyethylenesulfonic acid ion exchange membrane having a film thickness of 150 (μm) and an ion exchange capacity of 2.8 (meq / g-dry ion exchange membrane) A charge / discharge test was conducted in the same manner as in Example 1 except that was used.
実施例１において、前記イオン交換膜に代えて、膜厚が１５０（μｍ）であり、且つイオン交換容量が２．８（ｍｅｑ／ｇ－乾燥イオン交換膜）であるポリエチレンスルホン酸系イオン交換膜を用いたこと以外は実施例１と同様にして充放電試験を実施した。 (Comparative Example 1)
In Example 1, in place of the ion exchange membrane, a polyethylenesulfonic acid ion exchange membrane having a film thickness of 150 (μm) and an ion exchange capacity of 2.8 (meq / g-dry ion exchange membrane) A charge / discharge test was conducted in the same manner as in Example 1 except that was used.
（比較例２）
実施例１において、前記イオン交換膜に代えて、膜厚が２５（μｍ）であり、且つイオン交換容量が１．５（ｍｅｑ／ｇ－乾燥イオン交換膜）であるポリエチレンスルホン酸系イオン交換膜を用いたこと以外は実施例１と同様にして充放電試験を実施した。 (Comparative Example 2)
In Example 1, instead of the ion exchange membrane, a polyethylene sulfonic acid ion exchange membrane having a film thickness of 25 (μm) and an ion exchange capacity of 1.5 (meq / g-dry ion exchange membrane) A charge / discharge test was conducted in the same manner as in Example 1 except that was used.
実施例１において、前記イオン交換膜に代えて、膜厚が２５（μｍ）であり、且つイオン交換容量が１．５（ｍｅｑ／ｇ－乾燥イオン交換膜）であるポリエチレンスルホン酸系イオン交換膜を用いたこと以外は実施例１と同様にして充放電試験を実施した。 (Comparative Example 2)
In Example 1, instead of the ion exchange membrane, a polyethylene sulfonic acid ion exchange membrane having a film thickness of 25 (μm) and an ion exchange capacity of 1.5 (meq / g-dry ion exchange membrane) A charge / discharge test was conducted in the same manner as in Example 1 except that was used.
＜評価方法＞
（１）充放電電圧効率
実施例及び比較例において、正極活物質液及び負極活物質液を静止させた状態で、２００ｍＡ／ｃｍ２の定電流で充放電を行い、充放電電圧効率（％）を以下の式から求めた。結果を表１に示す。
充放電電圧効率（％）＝Ａ／Ｂ
ここで、Ａは充電電圧における最高値と最低値の中間の電圧値（Ｖ）、Ｂは放電電圧における最高値と最低値の中間の電圧値（Ｖ）を指す。 <Evaluation method>
(1) Charge / Discharge Voltage Efficiency In Examples and Comparative Examples, charge / discharge was performed at a constant current of 200 mA / cm 2 with the positive electrode active material liquid and the negative electrode active material liquid being stationary, and the charge / discharge voltage efficiency (%) Was obtained from the following equation. The results are shown in Table 1.
Charge / discharge voltage efficiency (%) = A / B
Here, A indicates a voltage value (V) between the highest value and the lowest value in the charging voltage, and B indicates a voltage value (V) between the highest value and the lowest value in the discharge voltage.
（１）充放電電圧効率
実施例及び比較例において、正極活物質液及び負極活物質液を静止させた状態で、２００ｍＡ／ｃｍ２の定電流で充放電を行い、充放電電圧効率（％）を以下の式から求めた。結果を表１に示す。
充放電電圧効率（％）＝Ａ／Ｂ
ここで、Ａは充電電圧における最高値と最低値の中間の電圧値（Ｖ）、Ｂは放電電圧における最高値と最低値の中間の電圧値（Ｖ）を指す。 <Evaluation method>
(1) Charge / Discharge Voltage Efficiency In Examples and Comparative Examples, charge / discharge was performed at a constant current of 200 mA / cm 2 with the positive electrode active material liquid and the negative electrode active material liquid being stationary, and the charge / discharge voltage efficiency (%) Was obtained from the following equation. The results are shown in Table 1.
Charge / discharge voltage efficiency (%) = A / B
Here, A indicates a voltage value (V) between the highest value and the lowest value in the charging voltage, and B indicates a voltage value (V) between the highest value and the lowest value in the discharge voltage.
（２）セル面積抵抗率
実施例及び比較例において、正極活物質液及び負極活物質液を３ｍｌ／ｍｉｎで送液し、それぞれ正極及び負極に流通させた状態で、２００ｍＡ／ｃｍ２の定電流で充電を行い、セル面積抵抗率（Ωｃｍ２）を以下の式から求めた。結果を表１に示す。
セル面積抵抗率（Ωｃｍ２）＝（Ａ－Ｂ）／２×電流密度（Ａｃｍ－２） (2) Cell area resistivity In Examples and Comparative Examples, the positive electrode active material liquid and the negative electrode active material liquid were fed at a rate of 3 ml / min, and the constant current of 200 mA / cm 2 was passed through the positive electrode and the negative electrode, respectively. The cell area resistivity (Ωcm 2 ) was determined from the following formula. The results are shown in Table 1.
Cell area resistivity (Ωcm 2 ) = (AB) / 2 × current density (Acm −2 )
実施例及び比較例において、正極活物質液及び負極活物質液を３ｍｌ／ｍｉｎで送液し、それぞれ正極及び負極に流通させた状態で、２００ｍＡ／ｃｍ２の定電流で充電を行い、セル面積抵抗率（Ωｃｍ２）を以下の式から求めた。結果を表１に示す。
セル面積抵抗率（Ωｃｍ２）＝（Ａ－Ｂ）／２×電流密度（Ａｃｍ－２） (2) Cell area resistivity In Examples and Comparative Examples, the positive electrode active material liquid and the negative electrode active material liquid were fed at a rate of 3 ml / min, and the constant current of 200 mA / cm 2 was passed through the positive electrode and the negative electrode, respectively. The cell area resistivity (Ωcm 2 ) was determined from the following formula. The results are shown in Table 1.
Cell area resistivity (Ωcm 2 ) = (AB) / 2 × current density (Acm −2 )
＜評価＞
以上の結果より、レドックス電池において、活物質濃度が１．８Ｍ以上である正極活物質液及び前記負極活物質液を用い、且つイオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、膜厚が１２０μｍ以下である隔膜を用いることによって、セル面積抵抗率を低下でき、正極活物質液及び負極活物質液を静止させた状態であっても、充放電電圧効率を向上できる効果が得られることがわかる。
従来の低出力密度セルでは、セル面積抵抗率が２．０～３．０Ωｃｍ２でも十分に小さい値とされてきたが、本発明によれば、これよりも更に小さいセル面積抵抗率、好ましくは１．０Ωｃｍ２以下のセル面積抵抗率を実現できることがわかる。 <Evaluation>
From the above results, in the redox battery, the positive electrode active material liquid having an active material concentration of 1.8 M or more and the negative electrode active material liquid were used, and the ion exchange capacity was 2.0 (meq / g-dry ion exchange membrane). As described above, by using a diaphragm having a film thickness of 120 μm or less, the cell area resistivity can be reduced, and the charge / discharge voltage efficiency is improved even when the positive electrode active material liquid and the negative electrode active material liquid are stationary. It turns out that the effect which can be obtained is acquired.
In the conventional low power density cell, the cell area resistivity has been set to a sufficiently small value even when the cell area resistivity is 2.0 to 3.0 Ωcm 2. However, according to the present invention, a cell area resistivity smaller than this, preferably It can be seen that a cell area resistivity of 1.0 Ωcm 2 or less can be realized.
以上の結果より、レドックス電池において、活物質濃度が１．８Ｍ以上である正極活物質液及び前記負極活物質液を用い、且つイオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、膜厚が１２０μｍ以下である隔膜を用いることによって、セル面積抵抗率を低下でき、正極活物質液及び負極活物質液を静止させた状態であっても、充放電電圧効率を向上できる効果が得られることがわかる。
従来の低出力密度セルでは、セル面積抵抗率が２．０～３．０Ωｃｍ２でも十分に小さい値とされてきたが、本発明によれば、これよりも更に小さいセル面積抵抗率、好ましくは１．０Ωｃｍ２以下のセル面積抵抗率を実現できることがわかる。 <Evaluation>
From the above results, in the redox battery, the positive electrode active material liquid having an active material concentration of 1.8 M or more and the negative electrode active material liquid were used, and the ion exchange capacity was 2.0 (meq / g-dry ion exchange membrane). As described above, by using a diaphragm having a film thickness of 120 μm or less, the cell area resistivity can be reduced, and the charge / discharge voltage efficiency is improved even when the positive electrode active material liquid and the negative electrode active material liquid are stationary. It turns out that the effect which can be obtained is acquired.
In the conventional low power density cell, the cell area resistivity has been set to a sufficiently small value even when the cell area resistivity is 2.0 to 3.0 Ωcm 2. However, according to the present invention, a cell area resistivity smaller than this, preferably It can be seen that a cell area resistivity of 1.0 Ωcm 2 or less can be realized.
（実施例３）
実施例１において、正極及び負極として、繊維径７～１０μｍのセルロース系の焼成炭素繊維を電解酸化処理によって主に繊維径５μｍ以下の炭素繊維フェルトとしたものを用い、これをそれぞれ厚さ２ｍｍとなるように設けた。
正極活物質液及び負極活物質液を３ｍｌ／ｍｉｎで送液し、それぞれ正極及び負極に流通させた状態で、２００ｍＡ／ｃｍ２の定電流で充電を行い、セル面積抵抗率（Ωｃｍ２）を求めた。結果を表２に示す。 (Example 3)
In Example 1, as a positive electrode and a negative electrode, cellulose-based baked carbon fibers having a fiber diameter of 7 to 10 μm were used as carbon fiber felts mainly having a fiber diameter of 5 μm or less by electrolytic oxidation treatment, and each of them was 2 mm in thickness. Was provided.
The positive electrode active material liquid and the negative electrode active material liquid were fed at a rate of 3 ml / min, and charged with a constant current of 200 mA / cm 2 in the state of flowing through the positive electrode and the negative electrode, respectively, and the cell area resistivity (Ωcm 2 ) was determined. Asked. The results are shown in Table 2.
実施例１において、正極及び負極として、繊維径７～１０μｍのセルロース系の焼成炭素繊維を電解酸化処理によって主に繊維径５μｍ以下の炭素繊維フェルトとしたものを用い、これをそれぞれ厚さ２ｍｍとなるように設けた。
正極活物質液及び負極活物質液を３ｍｌ／ｍｉｎで送液し、それぞれ正極及び負極に流通させた状態で、２００ｍＡ／ｃｍ２の定電流で充電を行い、セル面積抵抗率（Ωｃｍ２）を求めた。結果を表２に示す。 (Example 3)
In Example 1, as a positive electrode and a negative electrode, cellulose-based baked carbon fibers having a fiber diameter of 7 to 10 μm were used as carbon fiber felts mainly having a fiber diameter of 5 μm or less by electrolytic oxidation treatment, and each of them was 2 mm in thickness. Was provided.
The positive electrode active material liquid and the negative electrode active material liquid were fed at a rate of 3 ml / min, and charged with a constant current of 200 mA / cm 2 in the state of flowing through the positive electrode and the negative electrode, respectively, and the cell area resistivity (Ωcm 2 ) was determined. Asked. The results are shown in Table 2.
（実施例４）
実施例３において、正極及び負極をそれぞれ厚さ３ｍｍとなるように設けたこと以外は実施例３と同様にして、セル面積抵抗率（Ωｃｍ２）を求めた。結果を表２に示す。 Example 4
In Example 3, cell area resistivity (Ωcm 2 ) was determined in the same manner as in Example 3 except that the positive electrode and the negative electrode were each provided to have a thickness of 3 mm. The results are shown in Table 2.
実施例３において、正極及び負極をそれぞれ厚さ３ｍｍとなるように設けたこと以外は実施例３と同様にして、セル面積抵抗率（Ωｃｍ２）を求めた。結果を表２に示す。 Example 4
In Example 3, cell area resistivity (Ωcm 2 ) was determined in the same manner as in Example 3 except that the positive electrode and the negative electrode were each provided to have a thickness of 3 mm. The results are shown in Table 2.
＜評価＞
以上の結果より、フロー型レドックス電池において、特に炭素繊維の繊維径が５μｍ以下である場合に、正極及び負極の厚さをそれぞれ３ｍｍ以下にすることにより、セル面積抵抗率が好適に低下することがわかる。 <Evaluation>
From the above results, in the flow type redox battery, when the fiber diameter of the carbon fiber is 5 μm or less, the cell area resistivity is preferably lowered by setting the thickness of the positive electrode and the negative electrode to 3 mm or less, respectively. I understand.
以上の結果より、フロー型レドックス電池において、特に炭素繊維の繊維径が５μｍ以下である場合に、正極及び負極の厚さをそれぞれ３ｍｍ以下にすることにより、セル面積抵抗率が好適に低下することがわかる。 <Evaluation>
From the above results, in the flow type redox battery, when the fiber diameter of the carbon fiber is 5 μm or less, the cell area resistivity is preferably lowered by setting the thickness of the positive electrode and the negative electrode to 3 mm or less, respectively. I understand.
更に、以下の計算例により、実施例３のフロー型レドックス電池の電池単位体積当たりの定格出力密度を求めた。
バナジウムレドックス電池の開路電圧１．２Ｖ、セル面積抵抗１Ωｃｍ２、見掛けの電流密度２００ｍＡ／ｃｍ２のとき、単位面積当たりの出力電圧は、１．２Ｖ－０．２Ｖ＝１．０Ｖである。
よって、単位面積当たりの出力は、２００ｍＡ／ｃｍ２×１Ｖ＝０．２Ｗ／ｃｍ２である。
ここで、１０ｃｍ×１０ｃｍの電極を用いた場合、電極面積当たりの出力は、２０Ｗ／１００ｃｍ２である。
１セルを、厚さ４ｍｍで構成したとする。
このようなセルを、１０ｃｍ間に２５セル配置すれば、電池単位体積当たりの定格出力密度（体積１Ｌ当たりの出力）は、２０Ｗ×２５＝５００Ｗ／Ｌとなる。 Furthermore, the rated output density per unit cell volume of the flow type redox battery of Example 3 was obtained by the following calculation example.
Open circuit voltage 1.2V vanadium redox battery,cell area resistance 1 .OMEGA.cm 2, when the apparent current density of 200 mA / cm 2, the output voltage per unit area is 1.2V-0.2V = 1.0V.
Therefore, the output per unit area is 200 mA / cm 2 × 1V = 0.2 W / cm 2 .
Here, when an electrode of 10 cm × 10 cm is used, the output per electrode area is 20 W / 100 cm 2 .
Assume that one cell has a thickness of 4 mm.
If 25 such cells are arranged between 10 cm, the rated output density per unit battery volume (output per 1 L of volume) is 20 W × 25 = 500 W / L.
バナジウムレドックス電池の開路電圧１．２Ｖ、セル面積抵抗１Ωｃｍ２、見掛けの電流密度２００ｍＡ／ｃｍ２のとき、単位面積当たりの出力電圧は、１．２Ｖ－０．２Ｖ＝１．０Ｖである。
よって、単位面積当たりの出力は、２００ｍＡ／ｃｍ２×１Ｖ＝０．２Ｗ／ｃｍ２である。
ここで、１０ｃｍ×１０ｃｍの電極を用いた場合、電極面積当たりの出力は、２０Ｗ／１００ｃｍ２である。
１セルを、厚さ４ｍｍで構成したとする。
このようなセルを、１０ｃｍ間に２５セル配置すれば、電池単位体積当たりの定格出力密度（体積１Ｌ当たりの出力）は、２０Ｗ×２５＝５００Ｗ／Ｌとなる。 Furthermore, the rated output density per unit cell volume of the flow type redox battery of Example 3 was obtained by the following calculation example.
Open circuit voltage 1.2V vanadium redox battery,
Therefore, the output per unit area is 200 mA / cm 2 × 1V = 0.2 W / cm 2 .
Here, when an electrode of 10 cm × 10 cm is used, the output per electrode area is 20 W / 100 cm 2 .
Assume that one cell has a thickness of 4 mm.
If 25 such cells are arranged between 10 cm, the rated output density per unit battery volume (output per 1 L of volume) is 20 W × 25 = 500 W / L.
以上の実施例３に係る計算例で示されるように、本発明によると、条件設定によって、電池単位体積当たりの定格５００Ｗ／Ｌ以上の出力密度を実現することができると推定される。該条件設定を異ならせることで、定格出力密度を更に向上することもできる。また、他の実施例においても、条件設定を適宜設定することで、５００Ｗ／Ｌ以上を達成できると推定される。
As shown in the calculation example according to Example 3 described above, according to the present invention, it is estimated that a power density of 500 W / L or more per battery unit volume can be realized by setting conditions. By changing the condition setting, the rated output density can be further improved. In other examples, it is estimated that 500 W / L or more can be achieved by appropriately setting the condition settings.
＜考察＞
本発明は、一つの局面において、電池活物質元素であるバナジウム濃度を高く維持し（１．８Ｍ以上）、かつ、高濃度化によって発生する活物質析出やセル面積抵抗率の増大などの問題点を解決して、大きな出力密度が得られるレドックス電池を提供することを目的としている。高濃度化によって活物質液がゲル化する現象は、高濃度活物質液がチキソトロピー（揺変性）を示す結果であり、適度に流動状態を維持することによって解決でき、また、ビンガム流体性と矛盾しない。 <Discussion>
In one aspect, the present invention maintains a high concentration of vanadium, which is a battery active material element (1.8M or more), and also has problems such as active material precipitation and increase in cell area resistivity, which are generated by high concentration. It is an object of the present invention to provide a redox battery that can solve this problem and obtain a large output density. The phenomenon of gelation of the active material liquid due to high concentration is a result of the thixotropy (thixotropy) of the high concentration active material liquid, which can be solved by maintaining a proper fluid state, and is inconsistent with Bingham fluidity do not do.
本発明は、一つの局面において、電池活物質元素であるバナジウム濃度を高く維持し（１．８Ｍ以上）、かつ、高濃度化によって発生する活物質析出やセル面積抵抗率の増大などの問題点を解決して、大きな出力密度が得られるレドックス電池を提供することを目的としている。高濃度化によって活物質液がゲル化する現象は、高濃度活物質液がチキソトロピー（揺変性）を示す結果であり、適度に流動状態を維持することによって解決でき、また、ビンガム流体性と矛盾しない。 <Discussion>
In one aspect, the present invention maintains a high concentration of vanadium, which is a battery active material element (1.8M or more), and also has problems such as active material precipitation and increase in cell area resistivity, which are generated by high concentration. It is an object of the present invention to provide a redox battery that can solve this problem and obtain a large output density. The phenomenon of gelation of the active material liquid due to high concentration is a result of the thixotropy (thixotropy) of the high concentration active material liquid, which can be solved by maintaining a proper fluid state, and is inconsistent with Bingham fluidity do not do.
高濃度系バナジウム活物質液では、流動性の低下によって、ほかのイオンの易動性が大きく低下して、プロトンの輸率が大きくなる。ただし、そのプロトンも易動度そのものは、希薄な液に対して大きく低下する。これは結果として、活物質液の導電率低下に繋がり、電池としての内部抵抗（面積抵抗率）が大きくなってしまう。この問題点を解決する方法は、液抵抗の影響を最も大きく受ける隔膜部分の最小化（隔膜を薄くすること）であった。セル内電極部分は電極の導電性によって、活物質液の導電率低下の影響を緩和できる。ただし、電極面（炭素繊維表面）に活物質が速やかに到達できるようにするために炭素（グラファイト）繊維表面積を大きくする処置が性能向上を図る上で重要である。比表面積の増加によって、活物質の電極面への物質移動性を向上させるとともに、比表面積増加が電極そのものの導電性向上（体積抵抗率の軽減）に寄与している。
In the high-concentration type vanadium active material liquid, the mobility of other ions is greatly reduced due to the decrease in fluidity, and the proton transport number is increased. However, the mobility itself of the proton is greatly reduced with respect to a dilute liquid. As a result, this leads to a decrease in the conductivity of the active material liquid, and the internal resistance (area resistivity) of the battery increases. The method for solving this problem is minimization of the diaphragm portion (thinning the diaphragm) that is most affected by the liquid resistance. The electrode part in the cell can alleviate the influence of the decrease in the conductivity of the active material liquid due to the conductivity of the electrode. However, in order to enable the active material to quickly reach the electrode surface (carbon fiber surface), a treatment for increasing the carbon (graphite) fiber surface area is important for improving performance. The increase in the specific surface area improves the mass mobility of the active material to the electrode surface, and the increase in the specific surface area contributes to the improvement in conductivity (reduction in volume resistivity) of the electrode itself.
以上のような効果によって、高濃度系の活物質液であっても、高い反応性（見掛けの電流密度）を維持することができ、かつ、高濃度系である分だけ反応性を向上させることができるようになった。具体的には２００ｍＡ／ｃｍ２程度の電流密度の電池反応（充放電の電極反応）によって、５００Ｗ／Ｌ以上の出力密度を出せるレドックス電池を提供することも可能になった。この出力密度は、サイクル仕様の鉛二次電池を超えるものである。
Due to the above effects, high reactivity (apparent current density) can be maintained even with a high concentration active material solution, and the reactivity can be improved by the amount of the high concentration system. Can now. Specifically, it has become possible to provide a redox battery capable of producing a power density of 500 W / L or more by a battery reaction (charge / discharge electrode reaction) with a current density of about 200 mA / cm 2 . This power density exceeds that of a cycle-specification lead secondary battery.
１：正極セル
１１：正極
１２：流入口
１３：流出口
１４：正極活物質液タンク
１５：ポンプ
１６：流入管
１７：流出管
２：負極セル
２１：負極
２２：流入口
２３：流出口
２４：負極活物質液タンク
２５：ポンプ
２６：流入管
２７：流出管
３：隔膜
４：スペーサー
５：導電性シート
６：押え板
1: Positive electrode cell 11: Positive electrode 12: Inlet 13: Outlet 14: Positive electrode active material liquid tank 15: Pump 16: Inflow pipe 17: Outlet pipe 2: Negative electrode cell 21: Negative electrode 22: Inlet 23: Outlet 24: Negative electrode active material liquid tank 25: Pump 26: Inflow pipe 27: Outflow pipe 3: Separator 4: Spacer 5: Conductive sheet 6: Presser plate
１１：正極
１２：流入口
１３：流出口
１４：正極活物質液タンク
１５：ポンプ
１６：流入管
１７：流出管
２：負極セル
２１：負極
２２：流入口
２３：流出口
２４：負極活物質液タンク
２５：ポンプ
２６：流入管
２７：流出管
３：隔膜
４：スペーサー
５：導電性シート
６：押え板
1: Positive electrode cell 11: Positive electrode 12: Inlet 13: Outlet 14: Positive electrode active material liquid tank 15: Pump 16: Inflow pipe 17: Outlet pipe 2: Negative electrode cell 21: Negative electrode 22: Inlet 23: Outlet 24: Negative electrode active material liquid tank 25: Pump 26: Inflow pipe 27: Outflow pipe 3: Separator 4: Spacer 5: Conductive sheet 6: Presser plate
Claims (3)
- 正極活物質液を流通又は含浸させる正極と、
負極活物質液を流通又は含浸させる負極と、
前記正極と前記負極との間に設けられた隔膜とを備え、
前記正極活物質液及び前記負極活物質液は、それぞれ活物質濃度が１．８Ｍ以上であり、
前記隔膜は、イオン交換容量が２．０（ｍｅｑ／ｇ－乾燥イオン交換膜）以上であり、且つ膜厚が１２０μｍ以下であることを特徴とするレドックス電池。 A positive electrode for circulating or impregnating a positive electrode active material liquid;
A negative electrode that circulates or impregnates the negative electrode active material liquid;
A diaphragm provided between the positive electrode and the negative electrode,
Each of the positive electrode active material liquid and the negative electrode active material liquid has an active material concentration of 1.8 M or more,
The redox battery characterized in that the diaphragm has an ion exchange capacity of 2.0 (meq / g-dry ion exchange membrane) or more and a film thickness of 120 μm or less. - 前記正極及び前記負極は、それぞれ炭素繊維からなり、
前記炭素繊維の繊維径が１μｍ～１２μｍの範囲であり、かさ密度が０．５ｇ／ｍＬ～１．２ｇ／ｍＬの範囲であると共に、
前記隔膜面に垂直方向の前記正極及び前記負極の厚さが、前記正極活物質液及び前記負極活物質液を流通させて充放電を行う場合には、それぞれ３ｍｍ以下、前記正極活物質液及び前記負極活物質液を静止又は間欠的に流動させて充放電を行う場合には、それぞれ６ｍｍ以下であることを特徴とする請求項１記載のレドックス電池。 The positive electrode and the negative electrode are each made of carbon fiber,
The carbon fiber has a fiber diameter in the range of 1 μm to 12 μm, a bulk density in the range of 0.5 g / mL to 1.2 g / mL,
When the positive electrode and the negative electrode in the direction perpendicular to the diaphragm surface are charged and discharged by circulating the positive electrode active material liquid and the negative electrode active material liquid, the positive electrode active material liquid and 2. The redox battery according to claim 1, wherein when the negative electrode active material liquid is charged or discharged while flowing statically or intermittently, each of the redox batteries is 6 mm or less. - 前記正極活物質液及び前記負極活物質液は、それぞれ活物質としてバナジウムを含有し、バナジウム原子の含有量が１００ｇ／Ｌ以上であり、且つ硫酸根及び硫酸水素根としての硫黄原子の含有量が１２０ｇ／Ｌ以上であることを特徴とする請求項１又は２記載のレドックス電池。 Each of the positive electrode active material liquid and the negative electrode active material liquid contains vanadium as an active material, the content of vanadium atoms is 100 g / L or more, and the content of sulfur atoms as sulfate and hydrogen sulfate radicals It is 120 g / L or more, The redox battery of Claim 1 or 2 characterized by the above-mentioned.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017545822A JP6663923B2 (en) | 2015-10-23 | 2016-10-21 | Redox battery |
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| Application Number | Priority Date | Filing Date | Title |
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| JP2015209009 | 2015-10-23 | ||
| JP2015-209009 | 2015-10-23 |
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| WO2017069261A1 true WO2017069261A1 (en) | 2017-04-27 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/JP2016/081324 WO2017069261A1 (en) | 2015-10-23 | 2016-10-21 | Redox cell |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP6663923B2 (en) |
| WO (1) | WO2017069261A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2018133263A (en) * | 2017-02-16 | 2018-08-23 | 株式会社ギャラキシー | Battery active material liquid of flow type battery |
| JP2019201483A (en) * | 2018-05-16 | 2019-11-21 | 株式会社大原興商 | Power generation equipment |
| JP2021512458A (en) * | 2018-01-26 | 2021-05-13 | ユーシーエル ビジネス リミテッド | Flow battery |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09223513A (en) * | 1996-02-19 | 1997-08-26 | Kashimakita Kyodo Hatsuden Kk | Liquid circulating type battery |
-
2016
- 2016-10-21 JP JP2017545822A patent/JP6663923B2/en not_active Expired - Fee Related
- 2016-10-21 WO PCT/JP2016/081324 patent/WO2017069261A1/en active Application Filing
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09223513A (en) * | 1996-02-19 | 1997-08-26 | Kashimakita Kyodo Hatsuden Kk | Liquid circulating type battery |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2018133263A (en) * | 2017-02-16 | 2018-08-23 | 株式会社ギャラキシー | Battery active material liquid of flow type battery |
| JP2021512458A (en) * | 2018-01-26 | 2021-05-13 | ユーシーエル ビジネス リミテッド | Flow battery |
| JP7344884B2 (en) | 2018-01-26 | 2023-09-14 | ユーシーエル ビジネス リミテッド | flow battery |
| JP2019201483A (en) * | 2018-05-16 | 2019-11-21 | 株式会社大原興商 | Power generation equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| JP6663923B2 (en) | 2020-03-13 |
| JPWO2017069261A1 (en) | 2018-08-30 |
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