EP3317441A1 - Process for the preparation of carbon felt electrodes for redox flow batteries - Google Patents

Process for the preparation of carbon felt electrodes for redox flow batteries

Info

Publication number
EP3317441A1
EP3317441A1 EP16731595.1A EP16731595A EP3317441A1 EP 3317441 A1 EP3317441 A1 EP 3317441A1 EP 16731595 A EP16731595 A EP 16731595A EP 3317441 A1 EP3317441 A1 EP 3317441A1
Authority
EP
European Patent Office
Prior art keywords
felt
carbon
fibers
redox flow
metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP16731595.1A
Other languages
German (de)
French (fr)
Inventor
Rüdiger-Bernd SCHWEISS
Christian MEISER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SGL Carbon SE
Original Assignee
SGL Carbon SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SGL Carbon SE filed Critical SGL Carbon SE
Publication of EP3317441A1 publication Critical patent/EP3317441A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/18—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
    • D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
    • D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
    • D01F9/225—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles from stabilised polyacrylonitriles
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
    • D06M11/83—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with metals; with metal-generating compounds, e.g. metal carbonyls; Reduction of metal compounds on textiles
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/50—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with organometallic compounds; with organic compounds containing boron, silicon, selenium or tellurium atoms
    • D06M13/503—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with organometallic compounds; with organic compounds containing boron, silicon, selenium or tellurium atoms without bond between a carbon atom and a metal or a boron, silicon, selenium or tellurium atom
    • 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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • 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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • 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
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • 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
    • H01M8/184—Regeneration by electrochemical means
    • H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
    • D06M2101/16—Synthetic fibres, other than mineral fibres
    • D06M2101/18—Synthetic fibres consisting of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M2101/26—Polymers or copolymers of unsaturated carboxylic acids or derivatives thereof
    • D06M2101/28—Acrylonitrile; Methacrylonitrile
    • 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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • Y02E60/10—Energy storage using batteries
    • 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 invention relates to a process for the production of felt from metal-doped carbon fibers, as well as its use in a redox flow battery.
  • Redox flow batteries are secondary batteries that use active compounds in the form of aqueous solutions of metal salts or halides. Under operating conditions, redox flow batteries are pumped from external tanks into an electrochemical reactor where they are electrochemically converted during the charging or discharging process.
  • the reactor is designed as a stacked cell with a bipolar construction.
  • the single cells consist of two electrode spaces with porous carbon electrodes, which are separated by an ion-conducting membrane or a microporous separator. Due to many common features with the fuel cells (bipolar construction as a stack), redox flow batteries are also referred to as regenerative fuel cells.
  • the cells themselves are bounded by graphite plates which separate the individual cells and divert the streams along the stack.
  • power and capacitance can be dimensioned independently of one another, since the capacity is determined by the tank volumes or the concentration of redox-active species in the electrolyte, while the performance depends on the dimension, cell number and efficiency of the cell stack. Due to the modular structure and the decoupling of power and energy, flexible storage systems can be designed, which are particularly attractive for the electrochemical storage of energy from renewable sources (wind and solar power).
  • Redox flow batteries almost exclusively use carbon in the form of needle felts as flow-through electrodes, since the highly porous structure of the fiber skeleton ensures high electrical conductivity and at the same time good flow-through properties and homogeneous fluid distribution.
  • the three-dimensional structure has a high specific surface area (> 150 cm 2 / cm 3 or a BET surface area of 0.3 to 0.8 m 2 / g).
  • a high specific surface area > 150 cm 2 / cm 3 or a BET surface area of 0.3 to 0.8 m 2 / g.
  • V0 2+ / V0 2 +, Br 2 / Br ⁇ 3 or Cr 2 + / Cr + produce only moderate overvoltages.
  • Carbon materials such as carbon fibers or graphite are stable to aggressive electrolytes used in flow batteries (for example, vanadium, bromine, polysulfides or acids).
  • Carbon felts are compression-elastic and can be easily integrated into a filter press assembly of a stack. Carbon felts are produced industrially in a roll-to-roll process.
  • PAN polyacrylonitrile
  • PANOX oxidized polyacrylonitrile
  • PAN fibers are first produced by wet spinning of the polymer in a precipitation bath and then dried. By thermal oxidation of the PAN fibers creates a Stabilized (oxidized) PAN fiber, which is processed into a needle felt. Alternatively, a needled felt can be produced from PAN fibers and oxidatively stabilized.
  • Redox Flow batteries use aqueous solutions as active compounds. For this reason, the maximum available cell voltage is limited. Most redox systems require acidic conditions (up to 5 molar sulfuric acid, hydrochloric acid or bromine acid). The potential window is theoretically limited to 1.23V. During charging, problematic side reactions such as hydrogen formation on the negative electrode or corrosion of the positive electrode due to oxygen formation occur.
  • Carbon felts are treated at a temperature of over 2000 ° C to obtain a fiber of high crystallinity (graphitic character) (see, for example, DE2027130B).
  • this treatment only leads to a low wettability compared to the electrolyte systems.
  • carbon felts must be thermally treated in an oxygen-containing atmosphere prior to use to render the surface functional and wettable (see, for example, US6509119B1).
  • activation may be by electron or gamma irradiation and plasma treatment (see, for example, EP2626936A1).
  • a lower cell resistance of the battery is produced because the redox reactions of the active compositions are accelerated by catalytically active hydroxyl or carboxyl groups and the useful surface area of the electrodes is increased by improved wettability.
  • Hydrogen formation is a fundamental problem for the long-term behavior of redox flow batteries, as it represents an imbalance of electrolytes in the half-cells to capacity loss and additionally a security risk.
  • the capacity loss due to the electrolyte imbalance causes an increase in cell resistance.
  • a compensation cell can be used which electrochemically oxidizes the resulting hydrogen to water (see DE3843312A1) and thereby maintains the charge balance of the cell.
  • vanadium redox flow batteries similar catalysts / inhibitors based on nanoparticles have been proposed (Z. Gonzalez et al., Electrochemistry Communications, Vol. 13, 2011, pp. 379-1382). However, these must be introduced through elaborate measures in the felt, as well as produced by electrodeposition of electrolyte solutions.
  • the object of the invention is therefore to provide a carbon felt having an intrinsically high activity, so that no elaborate surface treatment of the felt is required to achieve an acceptable reduction of hydrogen formation.
  • This object is achieved by a method for the production of metal-doped felt from carbon fibers, wherein a textile structure of pre-oxidized polyacrylonitrile is carbonized at temperatures up to 1500 ° C and wherein precursor as polyacrylonitrile are functionalized with a metal precursor, which in the course of
  • Carbonization generates the corresponding metals in and on the fiber.
  • the object is further achieved by the use of the metal-doped felt produced by the process according to the invention in a redox flow battery.
  • the present invention thus claims a method in which catalytically active species are already integrated during the production of the carbon felt.
  • carbon felt felt according to the invention is understood: felt, needle felt, fabric and nonwoven fabric based on carbon fibers. Fibers are spun from a polyacrylonitrile polymer, typically producing a PAN spinning solution. These spun fibers represent the precursor fibers. The precursor fibers become then partially oxidized, whereby the pre-oxidized polyacrylonitrile be obtained.
  • the carbon felt thereby receives a doping with functional metals (for example, tin, bismuth, manganese, indium, lead, phosphorus and / or antimony).
  • functional metals for example, tin, bismuth, manganese, indium, lead, phosphorus and / or antimony.
  • the carbonation temperature must be below the evaporation temperature of the corresponding element.
  • particles of metals or semi-metals are produced which have a high overpotential for hydrogen formation, do not form carbides and are not toxic.
  • the doping with phosphine has positive effects on the oxidation resistance of the felt.
  • the battery felt can be produced surprisingly cost-effectively in a single carbonation step (instead of the usual two-step procedure).
  • the carbon felt retains a higher specific surface area and a high residual content of heteroatoms (oxygen, nitrogen).
  • the high residual content of heteroatoms produces improved charge-transfer kinetics of the active species.
  • the tendency for hydrogenation of partially graphitized or graphitized felts is reduced by the preferred equipment with inhibitors (particles of metals with high hydrogen overvoltage).
  • the particles are applied either by preferably doping the PAN spinning solution with metal nanoparticles, metal salts, metal oxide particles or organometallic compounds or by preferably impregnating the PAN fiber with solutions of metal salts, metal sulfides, metal oxides or metal-containing sol-gel precursors. This can be done, for example, by spraying on the fibers or through
  • the felt preferably has a thickness of 0.5 to 10 mm, more preferably 2 to 6 mm. This corresponds to battery requirements.
  • the basis weight is preferably 100 to 1000 g / m 2 , more preferably 200 to 600 g / m 2 . Thickness and basis weight correlate.
  • the BET surface area of the felt is preferably 0.4 to 10 m 2 / g, more preferably 0.4 to 1.5 m 2 / g.
  • the felt has a specific electrical resistance perpendicular to the felt direction of preferably 0.5 to 10 ohm mm, more preferably 1 to 4 ohm mm.
  • the felt has a carbon content of 90 to 99%, more preferably 92 to 98%.
  • the residual content results from nitrogen, oxygen and a marginal content of hydrogen. It is preferable that the nitrogen content is 0.2 to 5%.
  • the nitrogen is catalytically active, which makes the battery more efficient, since lower overvoltages of electrode reactions (eg vanadyl) are present.
  • the residual content is due to carbon, oxygen and a marginal content of hydrogen, ignoring ash and sulfur.
  • the felt has a lattice plane spacing of preferably 3.40 to 3.55 angstroms, more preferably 3.45 to 3.52 angstroms.
  • the proportions of tin, bismuth, manganese, indium, phosphorus and / or antimony are particularly preferably in each case from 200 to 10,000 ppm.
  • the hydrogen overvoltage is reduced (tin, bismuth, manganese, indium and / or antimony), whereby the capacity loss during a charging of a battery is reduced.
  • Phosphorus serves as a corrosion inhibitor.
  • the metal-doped felt is preferably used in a redox flow battery.
  • a solution, or dispersion, is prepared from 1 weight percent bismuth (III) isopropoxide in water / isopropanol (9: 1).
  • a solution or dispersion is prepared from 0.5% by weight of bismuth (III) isopropoxide, 0.5% by weight of bismuth hexanoate and 0.4% by weight of tin isopropylate in water / isopropanol (9: 1).
  • Dispersion IC :
  • a solution, or dispersion, is prepared from 1 weight percent bismuth hexanoate, 0.5 weight percent indium (III) isopropylate and 0.3 weight percent antimony (III) isopropylate in water / isopropanol (9: 1).
  • Polyacrylonitrile (1.7 dtex or 2.2 dtex) carbon precursor fibers are each impregnated with the described dispersions (1A, 1B, 1C), dried and stabilized by thermal oxidation under air atmosphere at 240-280 ° C.
  • the resulting fibers are made into crimped staple fibers (62 mm fiber length). After carding / carding these fibers are deposited into a single or multi-ply pile and processed by one or both sides needling to a felt (basis weight of 200 to 800 g / m2). Subsequently, a carbonization under a protective gas atmosphere in a continuous furnace at a temperature of 1480 ° C.
  • a reference pattern without addition of metal compounds was carbonized in the same way (comparative example 2).
  • As a further reference material (comparative sample 1) used was a commercial, graphitized carbon felt Sigracell ® GFD 4.6 (SGL Carbon GmbH, Meitingen)
  • Weight percent bismuth (III) oxide (nanoscale 80-200 nm) and 1 weight percent indium isopropoxide and polymer fibers produced by wet spinning. After thermal oxidation of the fibers under air atmosphere at 280 ° C, these are processed into crimped staple fibers (62 mm fiber length). After carding / carding these fibers are stored in a single or multi-ply pile and by one or double-sided needling (surface masses from 400 to 700 g / m2) into a felt. Subsequently, a carbonization under a protective gas atmosphere in a continuous furnace at a temperature of 1480 ° C.
  • the felts and the reference material were examined in a vanadium redox flow battery single cell with an electrode area of 20 cm 2 .
  • the materials were each attached to the anode and cathode with a installed at 75% of the original thickness.
  • the separator used was a partially fluorinated anion exchange membrane (Fumasep FAP 450, Fumatech GmbH, Bietigheim-Bissingen) and graphite compound plates as current conductors. All cell tests were performed with 0.8 M vanadium / 4M sulfate and electrolyte flow rates of 80 mL / min.
  • the cells were conditioned by a full charge of the electrolyte.
  • 3 consecutive charge / discharge cycles charge end voltage 1.65 V, discharge voltage 0.9 V were carried out in each case at current densities of 20 to 60 mA / cm 2 .
  • the cycles resistors was 2.9 Ohm x cm 2 (comparative sample 1), 2.3 Ohm x cm 2 (Comparative sample 2), 2.0 Ohm x cm 2 (Embodiment 1 dispersion 1A) and 2.1 Ohm x cm 2 (Embodiment 2) determined.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Textile Engineering (AREA)
  • Electrochemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Inert Electrodes (AREA)
  • Fuel Cell (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Inorganic Fibers (AREA)

Abstract

The object of the invention is a process for the preparation of metal-doped felt fabric made of carbon fibers, wherein a textile structure of pre-oxidized polyacrylonitrile fibers is carbonized at temperatures of up to 1500 °C and wherein polyacrylonitrile and/or oxidized polyacrylonitrile as precursor fibers are functionalized with a metal precursor.

Description

VERFAHREN ZUR HERSTELLUNG VON KOHLENSTOFFFILZELEKTRODEN  METHOD FOR PRODUCING CARBON FELT ELECTRODES
FÜR REDOX FLOW BATTERIEN  FOR REDOX FLOW BATTERIES
Gegenstand der Erfindung ist ein Verfahren zur Herstellung von Filz aus metalldotierten Kohlenstofffasern, sowie dessen Verwendung in einer Redox Flow Batterie. The invention relates to a process for the production of felt from metal-doped carbon fibers, as well as its use in a redox flow battery.
Als Redox Flow Batterien werden sekundäre Batterien bezeichnet, die Aktivmassen in Form wässriger Lösungen von Metallsalzen oder Halogeniden verwenden. Unter Betriebsbedingungen werden Redox Flow Batterien aus externen Tanks in einen elektrochemischen Reaktor gepumpt und dort beim Lade- bzw. Entladevorgang elektrochemisch umgesetzt. Redox flow batteries are secondary batteries that use active compounds in the form of aqueous solutions of metal salts or halides. Under operating conditions, redox flow batteries are pumped from external tanks into an electrochemical reactor where they are electrochemically converted during the charging or discharging process.
Der Reaktor wird als Zellstapel (Stack) mit bipolarer Bauweise ausgeführt. Die Einzelzellen bestehen aus zwei Elektrodenräumen mit porösen Kohlenstoffelektroden, welche durch eine ionenleitende Membran oder einen mikroporösen Separator getrennt werden. Aufgrund vieler gemeinsamer Merkmale mit den Brennstoffzellen (bipolare Bauweise als Stapel) werden Redox Flow Batterien auch als regenerative Brennstoffzellen bezeichnet. The reactor is designed as a stacked cell with a bipolar construction. The single cells consist of two electrode spaces with porous carbon electrodes, which are separated by an ion-conducting membrane or a microporous separator. Due to many common features with the fuel cells (bipolar construction as a stack), redox flow batteries are also referred to as regenerative fuel cells.
Die Zellen selbst werden durch Graphitplatten begrenzt, welche die Einzelzellen voneinander trennen und die Ströme entlang des Stapels ableiten. Im Gegensatz zu üblichen Sekundärbatterien können Leistung und Kapazität unabhängig voneinander dimensioniert werden, da die Kapazität durch die Tankvolumina bzw. die Konzentration der redoxaktiven Spezies im Elektrolyten bestimmt wird, während die Leistung von Dimension, Zellenzahl und Effizienz des Zellstapels abhängt. Durch den modularen Aufbau und die Entkopplung von Leistung und Energie lassen sich flexible Speicheranlagen auslegen, welche vor allem für die elektrochemische Speicherung von Energie aus regenerativen Quellen (Wind- und Solarstrom) attraktiv sind. The cells themselves are bounded by graphite plates which separate the individual cells and divert the streams along the stack. In contrast to conventional secondary batteries, power and capacitance can be dimensioned independently of one another, since the capacity is determined by the tank volumes or the concentration of redox-active species in the electrolyte, while the performance depends on the dimension, cell number and efficiency of the cell stack. Due to the modular structure and the decoupling of power and energy, flexible storage systems can be designed, which are particularly attractive for the electrochemical storage of energy from renewable sources (wind and solar power).
Redox Flow Batterien verwenden fast ausschließlich Kohlenstoff in Form von Nadelfilzen als Durchflusselektroden, da die hochporöse Struktur des Faserskeletts eine hohe elektrische Leitfähigkeit und gleichzeitig eine gute Durchströmbarkeit und eine homogene Fluidverteilung gewährleistet. Redox flow batteries almost exclusively use carbon in the form of needle felts as flow-through electrodes, since the highly porous structure of the fiber skeleton ensures high electrical conductivity and at the same time good flow-through properties and homogeneous fluid distribution.
Die dreidimensionale Struktur weist eine hohe spezifische Oberfläche auf (> 150 cm2/cm3 bzw. eine BET-Oberfläche von 0.3 bis 0.8 m2/g). Dadurch werden effektive Stromdichten herabgesetzt und kinetisch gehemmte Redoxpaare wie V2+/V +, The three-dimensional structure has a high specific surface area (> 150 cm 2 / cm 3 or a BET surface area of 0.3 to 0.8 m 2 / g). As a result, effective current densities are reduced and kinetically inhibited redox couples such as V 2+ / V + ,
V02+/V02 +, Br2/Br3 ~ oder Cr2+/Cr +erzeugen nur moderate Überspannungen. V0 2+ / V0 2 +, Br 2 / Br ~ 3 or Cr 2 + / Cr + produce only moderate overvoltages.
Kohlenstoffmaterialien wie Carbonfasern oder Graphit sind stabil gegen aggressive Elektrolyten, welche in Flowbatterien eingesetzt werden (beispielsweise Vanadium, Brom, Polysulfide oder Säuren). Carbon materials such as carbon fibers or graphite are stable to aggressive electrolytes used in flow batteries (for example, vanadium, bromine, polysulfides or acids).
Kohlenstofffilze sind kompressionselastisch und lassen sich in einem Filterpressen-Aufbau eines Stapels leicht integrieren. Kohlenstofffilze werden großtechnisch in einem Rolle-zu-Rolle Verfahren hergestellt. Carbon felts are compression-elastic and can be easily integrated into a filter press assembly of a stack. Carbon felts are produced industrially in a roll-to-roll process.
Für Redox Flow Batterien werden Kohlenstofffilze auf Basis von Polyacrylnitril (PAN) oder oxidiertem Polyacrylnitril (PANOX) hergestellt. For redox flow batteries, carbon felts based on polyacrylonitrile (PAN) or oxidized polyacrylonitrile (PANOX) are produced.
PAN-Fasern werden zunächst durch Nassspinnen des Polymers in einem Fällbad erzeugt und anschließend getrocknet. Durch thermische Oxidation der PAN-Fasern entsteht eine stabilisierte (oxidierte) PAN-Faser, die zu einem Nadelfilz verarbeitet wird. Alternativ kann aus PAN-Fasern ein Nadelfilz erzeugt und oxidativ stabilisiert werden. PAN fibers are first produced by wet spinning of the polymer in a precipitation bath and then dried. By thermal oxidation of the PAN fibers creates a Stabilized (oxidized) PAN fiber, which is processed into a needle felt. Alternatively, a needled felt can be produced from PAN fibers and oxidatively stabilized.
Anschließend erfolgt bei Temperaturen über 2000°C eine mehrstufige Pyrolyse der Filze unter Luftausschluss zu Kohlenstofffilzen mit sehr guter elektrischer Leitfähigkeit und hoher Reinheit (Aschegehalt < 0,2%). Subsequently, at temperatures above 2000 ° C, a multi-stage pyrolysis of the felts with exclusion of air to carbon felts with very good electrical conductivity and high purity (ash content <0.2%).
Redox Flow Batterien verwenden wässrige Lösungen als Aktivmassen. Aus diesem Grund ist die maximal erhältliche Zellspannung limitiert. Die meisten Redoxsysteme erfordern saure Bedingungen (bis 5 molare Schwefelsäure, Salzsäure oder Brom Wasserstoff säure). Das Potentialfenster ist auf theoretisch 1,23 V beschränkt. Beim Laden treten problematische Nebenreaktionen wie Wasserstoffbildung an der negativen Elektrode oder Korrosion der positiven Elektrode durch Sauerstoffbildung auf. Redox Flow batteries use aqueous solutions as active compounds. For this reason, the maximum available cell voltage is limited. Most redox systems require acidic conditions (up to 5 molar sulfuric acid, hydrochloric acid or bromine acid). The potential window is theoretically limited to 1.23V. During charging, problematic side reactions such as hydrogen formation on the negative electrode or corrosion of the positive electrode due to oxygen formation occur.
Ohne die kinetische Hemmung der Wasserstoffbildung (Überspannung) an Kohlenstoffmaterialien könnten daher im sauren Milieu keine Redoxpaare mit einem negativen elektrochemischen Standardpotential als negative Massen verwendet werden. Graphit weist beispielsweise eine hinreichend hohe Überspannung (> 0,5 Volt) gegenüber der Wasserstoffentwicklung auf und kann daher als Elektrodenmaterial eingesetzt werden. Without the kinetic inhibition of hydrogen formation (overvoltage) on carbon materials, therefore, no redox couples with a negative electrochemical standard potential could be used as negative masses in an acidic medium. Graphite has, for example, a sufficiently high overvoltage (> 0.5 volts) compared to the evolution of hydrogen and can therefore be used as electrode material.
Kohlenstofffilze werden bei einer Temperatur von über 2000°C behandelt, um eine Faser von hoher Krista llinität (graphitischer Charakter) zu erhalten (siehe beispielsweise DE2027130B). Diese Behandlung führt allerdings nur zu einer geringen Benetzbarkeit gegenüber den Elektrolytsystemen. Carbon felts are treated at a temperature of over 2000 ° C to obtain a fiber of high crystallinity (graphitic character) (see, for example, DE2027130B). However, this treatment only leads to a low wettability compared to the electrolyte systems.
Daher müssen Kohlenstofffilze vor der Verwendung thermisch in einer sauerstoffhaltigen Atmosphäre behandelt werden, um die Oberfläche zu funktionalisieren und benetzbar zu machen (siehe beispielsweise US6509119B1). Alternativ kann eine Aktivierung durch Elektronen- oder Gammabestrahlung sowie Plasmabehandlung (siehe beispielsweise EP2626936A1) erfolgen. Dadurch wird ein geringerer Zellwiderstand der Batterie erzeugt, weil die Redoxreaktionen der Aktivmassen durch katalytisch wirkende Hydroxyl- oder Carboxylgruppen beschleunigt und die nutzbare Oberfläche der Elektroden durch verbesserte Benetzbarkeit erhöht wird. Therefore, carbon felts must be thermally treated in an oxygen-containing atmosphere prior to use to render the surface functional and wettable (see, for example, US6509119B1). Alternatively, activation may be by electron or gamma irradiation and plasma treatment (see, for example, EP2626936A1). As a result, a lower cell resistance of the battery is produced because the redox reactions of the active compositions are accelerated by catalytically active hydroxyl or carboxyl groups and the useful surface area of the electrodes is increased by improved wettability.
Ähnliche Effekte können zwar auch bei einer reduzierten Herstellungstemperatur der Kohlenstofffilze erzielt werden, jedoch ist dann eine deutliche Neigung zur Wasserstoffbildung zu beobachten (N. Hagedorn, NASA Redox Storage System Development Project, Abschlussbericht DOE/NASA/12726-24, NASA TM-83677, 1984). Although similar effects can be achieved even with a reduced production temperature of the carbon felts, a marked tendency to hydrogen formation is observed (N. Hagedorn, NASA Redox Storage Systems Development Project, Final Report DOE / NASA / 12726-24, NASA TM-83677, 1984).
Wasserstoffbildung ist ein grundsätzliches Problem für das Langzeitverhalten von Redox Flow Batterien, da diese über ein Ungleichgewicht von Elektrolyten in den Halbzellen zu Kapazitätsverlust und zusätzlich ein Sicherheitsrisiko darstellt. Zudem ist mit dem Kapazitätsverlust infolge des Elektrolytungleichgewichts ein Anstieg des Zellwiderstands verbunden. Hydrogen formation is a fundamental problem for the long-term behavior of redox flow batteries, as it represents an imbalance of electrolytes in the half-cells to capacity loss and additionally a security risk. In addition, the capacity loss due to the electrolyte imbalance causes an increase in cell resistance.
Bei Eisen-Chrom Redox Flow Batterien wurden daher binäre Katalysatoren auf Basis von Gold und Thallium durch elektrochemische Abscheidung auf Kohlenstoffelektroden verwendet, welche die Wasserstoffbildung reduzieren und die Reaktivität des Filzes gegenüber dem Redoxpaar Cr2+/Cr + erhöhen (CD. Wu et al., J. Electrochem. Soc. 1986 Band 133, S. 2109-2112). US2014/0186731A beschreibt die Verwendung von Bismut im Elektrolyt als Wasserstoffinhibitor. In the case of iron-chromium redox flow batteries, therefore, binary catalysts based on gold and thallium were used by electrochemical deposition on carbon electrodes, which reduce hydrogen formation and increase the reactivity of the felt compared to the redox couple Cr 2+ / Cr + (CD, Wu et al. , J. Electrochem, Soc., 1986, Volume 133, pp. 2109-2112). US2014 / 0186731A describes the use of bismuth in the electrolyte as a hydrogen inhibitor.
Alternativ kann eine Ausgleichszelle verwendet werden, welche den entstandenen Wasserstoff elektrochemisch zu Wasser oxidiert (siehe DE3843312A1) und dadurch die Ladungsbilanz der Zelle aufrecht erhält. Für Vanadium Redox Flow Batterien wurden ähnliche Katalysatoren/Inhibitoren auf Basis von Nanopartikeln vorgeschlagen (Z. Gonzalez et al., Electrochemistry Communications, Band 13, 2011, S. 379-1382). Allerdings müssen diese über aufwendige Maßnahmen in den Filz eingebracht werden, sowie durch galvanische Abscheidung aus Elektrolytlösungen erzeugt werden. Alternatively, a compensation cell can be used which electrochemically oxidizes the resulting hydrogen to water (see DE3843312A1) and thereby maintains the charge balance of the cell. For vanadium redox flow batteries, similar catalysts / inhibitors based on nanoparticles have been proposed (Z. Gonzalez et al., Electrochemistry Communications, Vol. 13, 2011, pp. 379-1382). However, these must be introduced through elaborate measures in the felt, as well as produced by electrodeposition of electrolyte solutions.
Aufgabe der Erfindung ist es daher, einen Kohlenstofffilz bereitzustellen, der eine intrinsisch hohe Aktivität aufweist, so dass keine aufwändige Oberflächenbehandlung des Filzes erforderlich ist, um eine akzeptable Reduzierung der Wasserstoffbildung zu erreichen. The object of the invention is therefore to provide a carbon felt having an intrinsically high activity, so that no elaborate surface treatment of the felt is required to achieve an acceptable reduction of hydrogen formation.
Gelöst wird diese Aufgabe durch ein Verfahren zur Herstellung von metalldotiertem Filz aus Kohlenstofffasern, wobei eine textile Struktur aus präoxidierten Polyacrylnitrilfasern bei Temperaturen bis 1500°C karbonisiert wird und wobei als Präkursorfasern Polyacryl- nitril mit einem Metallpräkursor funktionalisiert sind, welcher im Zuge der This object is achieved by a method for the production of metal-doped felt from carbon fibers, wherein a textile structure of pre-oxidized polyacrylonitrile is carbonized at temperatures up to 1500 ° C and wherein precursor as polyacrylonitrile are functionalized with a metal precursor, which in the course of
Karbonisierung die entsprechenden Metalle in und an der Faser erzeugt. Carbonization generates the corresponding metals in and on the fiber.
Die Aufgabe wird ferner gelöst durch die Verwendung des nach dem erfindungsgemäßen Verfahren hergestellten metalldotierten Filzes in einer Redox Flow Batterie. The object is further achieved by the use of the metal-doped felt produced by the process according to the invention in a redox flow battery.
Die vorliegende Erfindung beansprucht somit ein Verfahren, bei dem katalytisch aktive Spezies bereits im Zuge der Herstellung des Kohlenstofffilzes integriert werden. Unter Kohlen stoff filz im Sinne der Erfindung wird verstanden: Filz, Nadelfilz, Gewebe und Vliesstoff auf Basis von Kohlenstofffasern. Aus einem Polyacrylnitril Polymer werden Fasern gesponnen, dabei wird typischerweise eine PAN-Spinnlösung hergestellt. Diese gesponnenen Fasern stellen die Präkursorfasern dar. Die Präkursorfasern werden anschließend teilweise oxidiert, wodurch die präoxidierten Polyacrylnitrilfasern erhalte werden. The present invention thus claims a method in which catalytically active species are already integrated during the production of the carbon felt. Under carbon felt felt according to the invention is understood: felt, needle felt, fabric and nonwoven fabric based on carbon fibers. Fibers are spun from a polyacrylonitrile polymer, typically producing a PAN spinning solution. These spun fibers represent the precursor fibers. The precursor fibers become then partially oxidized, whereby the pre-oxidized polyacrylonitrile be obtained.
Der Kohlenstofffilz erhält dadurch eine Dotierung mit funktionalen Metallen (beispielsweise Zinn, Bismut, Mangan, Indium, Blei, Phosphor und/oder Antimon). Bei der Karbonisierung werden aus den Metalloxiden an der Faseroberfläche durch Reduktion mit dem zuvor entstandenen Kohlenstoff die entsprechenden Metalle freigesetzt. The carbon felt thereby receives a doping with functional metals (for example, tin, bismuth, manganese, indium, lead, phosphorus and / or antimony). During carbonization, the corresponding metals are liberated from the metal oxides on the fiber surface by reduction with the previously formed carbon.
Die Karbonisierungstemperatur muss unter der Verdampfungstemperatur des entsprechenden Elements liegen. Vorzugsweise werden Partikel von Metallen oder Halbmetallen erzeugt, welche eine hohe Überspannung für die Wasserstoffbildung aufweisen, keine Carbide bilden und nicht toxisch sind. Bevorzugt im Sinne der Erfindung sind Bismut (Siedepunkt 1550°C), Zinn (Siedepunkt 2600°C), Indium (Siedepunkt 2000°C), Man gan (Siedepunkt 2100°C) und Antimon (Siedepunkt 1635°C). Die Dotierung mit Phosphf hat positive Auswirkungen auf die Oxidationsbeständigkeit des Filzes. The carbonation temperature must be below the evaporation temperature of the corresponding element. Preferably, particles of metals or semi-metals are produced which have a high overpotential for hydrogen formation, do not form carbides and are not toxic. For the purposes of the invention, preference is given to bismuth (boiling point 1550 ° C.), tin (boiling point 2600 ° C.), indium (boiling point 2000 ° C.), man gan (boiling point 2100 ° C.) and antimony (boiling point 1635 ° C.). The doping with phosphine has positive effects on the oxidation resistance of the felt.
Durch eine reduzierte Karbonisierungstemperatur von besonders bevorzugt < 1500°C kann der Batteriefilz überraschend kostengünstig in nur einem einzigen Karboni- sierungsschritt (statt wie sonst üblich in zwei Schritten) erzeugt werden. As a result of a reduced carbonization temperature of particularly preferably <1500 ° C., the battery felt can be produced surprisingly cost-effectively in a single carbonation step (instead of the usual two-step procedure).
Aufgrund der niedrigeren Behandlungstemperatur behält der Kohlenstofffilz eine höhere spezifische Oberfläche und einen hohen Restgehalt an Heteroatomen (Sauerstoff, Stickstoff). Der hohe Restgehalt an Heteroatomen erzeugt eine verbesserte Ladungstransferkinetik der aktiven Spezies. Die Neigung zur Wasserstoffbildung von teilgraphitierten oder graphitierten Filzen wird durch die bevorzugte Ausrüstung mit In hibitoren (Partikel von Metallen mit hoher Wasserstoffüberspannung) reduziert. Das Aufbringen der Partikel erfolgt entweder durch vorzugsweise Dotierung der PAN- Spinnlösung mit Metall-Nanopartikeln, Metallsalzen, Metalloxidpartikeln oder metallorganischen Verbindungen oder durch vorzugsweise Imprägnierung der PAN-Faser mit Lösungen von Metallsalzen, Metallsulfiden, Metalloxiden oder metallhaltigen Sol-Gel- Präkursoren. Dies kann beispielsweise durch Aufsprühen auf die Fasern oder durchDue to the lower treatment temperature, the carbon felt retains a higher specific surface area and a high residual content of heteroatoms (oxygen, nitrogen). The high residual content of heteroatoms produces improved charge-transfer kinetics of the active species. The tendency for hydrogenation of partially graphitized or graphitized felts is reduced by the preferred equipment with inhibitors (particles of metals with high hydrogen overvoltage). The particles are applied either by preferably doping the PAN spinning solution with metal nanoparticles, metal salts, metal oxide particles or organometallic compounds or by preferably impregnating the PAN fiber with solutions of metal salts, metal sulfides, metal oxides or metal-containing sol-gel precursors. This can be done, for example, by spraying on the fibers or through
Tauchen der Fasern in die Lösungen geschehen. Dip the fibers into the solutions done.
Der Filz weist bevorzugt eine Dicke von 0,5 bis 10 mm, besonders bevorzugt 2 bis 6 mm, auf. Dies entspricht Batterieanforderungen. The felt preferably has a thickness of 0.5 to 10 mm, more preferably 2 to 6 mm. This corresponds to battery requirements.
Das Flächengewicht beträgt bevorzugt 100 bis 1000 g/m2, besonders bevorzugt 200 bis 600 g/m2. Dicke und Flächengewicht korrelieren. The basis weight is preferably 100 to 1000 g / m 2 , more preferably 200 to 600 g / m 2 . Thickness and basis weight correlate.
Die BET-Oberfläche des Filzes beträgt bevorzugt 0,4 bis 10 m2/g, besonders bevorzugt 0,4 bis 1,5 m2/g. The BET surface area of the felt is preferably 0.4 to 10 m 2 / g, more preferably 0.4 to 1.5 m 2 / g.
Der Filz weist einen spezifischen elektrischen Widerstand senkrecht zur Filzrichtung von bevorzugt 0,5 bis 10 Ohm mm auf, besonders bevorzugt 1 bis 4 Ohm mm. Vorzugsweise weist der Filz einen Kohlenstoffgehalt von 90 bis 99 %, besonders bevorzugt 92 bis 98 %, auf. Wie im Ausführungsbeispiel im Detail beschrieben, ergibt sich der Restgehalt (um auf 100% zu kommen) durch Stickstoff, Sauerstoff und einen marginalen Gehalt an Wasserstoff. Es ist bevorzugt, dass der Stickstoffanteil 0,2 bis 5 % beträgt. Der Stickstoff ist katalytisch aktiv, wodurch die Batterie effizienter wird, da geringere Überspannungen von Elektrodenreaktionen (z.B. Vanadyl) vorliegen. Wie im Ausführungsbeispiel im Detail beschrie- ben, ergibt sich der Restgehalt durch Kohlenstoff, Sauerstoff und einen marginalen Gehalt an Wasserstoff, wobei Asche und Schwefel nicht berücksichtigt werden. The felt has a specific electrical resistance perpendicular to the felt direction of preferably 0.5 to 10 ohm mm, more preferably 1 to 4 ohm mm. Preferably, the felt has a carbon content of 90 to 99%, more preferably 92 to 98%. As described in detail in the exemplary embodiment, the residual content (to come to 100%) results from nitrogen, oxygen and a marginal content of hydrogen. It is preferable that the nitrogen content is 0.2 to 5%. The nitrogen is catalytically active, which makes the battery more efficient, since lower overvoltages of electrode reactions (eg vanadyl) are present. As described in detail in the exemplary embodiment. ben, the residual content is due to carbon, oxygen and a marginal content of hydrogen, ignoring ash and sulfur.
Der Filz weist einen Netzebenenabstand von bevorzugt 3,40 bis 3,55 Angstrom, besonders bevorzugt 3,45 bis 3,52 Angstrom, auf. The felt has a lattice plane spacing of preferably 3.40 to 3.55 angstroms, more preferably 3.45 to 3.52 angstroms.
Besonders bevorzugt betragen bei dem erfindungsgemäßen Metall dotierten Filz die Anteile an Zinn, Bismut, Mangan, Indium, Phosphor und/oder Antimon jeweils 200 bis 10000 ppm. Dadurch wird die Wasserstoffüberspannung vermindert (Zinn, Bismut, Mangan, Indium und/oder Antimon), wodurch der Kapazitätsverlust während eines Ladevorgangs einer Batterie reduziert wird. Phosphor dient als Korrosionsinhibitor. In the case of the metal-doped felt according to the invention, the proportions of tin, bismuth, manganese, indium, phosphorus and / or antimony are particularly preferably in each case from 200 to 10,000 ppm. As a result, the hydrogen overvoltage is reduced (tin, bismuth, manganese, indium and / or antimony), whereby the capacity loss during a charging of a battery is reduced. Phosphorus serves as a corrosion inhibitor.
Der metalldotierte Filz wird vorzugsweise in einer Redox Flow Batterie eingesetzt. The metal-doped felt is preferably used in a redox flow battery.
Die nachfolgenden Ausführungsbeispiele dienen zur näheren Erläuterung der Erfindung. The following embodiments serve to illustrate the invention.
Ausführungsbeispiel 1 Embodiment 1
Dispersion 1A: Dispersion 1A:
Eine Lösung, beziehungsweise Dispersion, wird hergestellt aus 1 Gewichtprozent Bismut(lll)-isopropoxid in Wasser/Isopropanol (9:1)  A solution, or dispersion, is prepared from 1 weight percent bismuth (III) isopropoxide in water / isopropanol (9: 1).
Dispersion 1B: Dispersion 1B:
Eine Lösung, beziehungsweise Dispersion, wird hergestellt aus 0.5 Gewichtsprozent Bismut(lll)-isopropoxid, 0.5 Gewichtsprozent Bismut-hexanoat und 0.4 Gewichtsprozent Zinn-isopropylat in Wasser/Isopropanol (9:1) Dispersion IC: A solution or dispersion is prepared from 0.5% by weight of bismuth (III) isopropoxide, 0.5% by weight of bismuth hexanoate and 0.4% by weight of tin isopropylate in water / isopropanol (9: 1). Dispersion IC:
Eine Lösung, beziehungsweise Dispersion, wird hergestellt aus 1 Gewichtsprozent Bismut-hexanoat, 0.5 Gewichtsprozent lndium(lll)-isopropylat und 0.3 Gewichtsprozent Antimon (lll)-isopropylat in Wasser/Isopropanol (9:1).  A solution, or dispersion, is prepared from 1 weight percent bismuth hexanoate, 0.5 weight percent indium (III) isopropylate and 0.3 weight percent antimony (III) isopropylate in water / isopropanol (9: 1).
Kohlenstoff-Präkursorfasern aus Polyacrylnitril (1.7 dtex oder 2.2 dtex) werden jeweils mit der beschriebenen Dispersionen (1A,1B,1C) imprägniert, getrocknet und durch thermische Oxidation unter Luftatmosphäre bei 240-280°C stabilisiert. Die so erhaltenen Fasern werden zu gekräuselten Stapelfasern verarbeitet (62 mm Faserlänge). Nach Krempeln/Kardieren werden diese Fasern zu einem ein- oder mehrlagigen Flor abgelegt und durch ein- oder beidseitige Vernadelung zu einem Filz (Flächenmasse von 200 bis 800 g/m2) verarbeitet. Anschließend erfolgt eine Karbonisierung unter Schutzgasatmosphäre in einem kontinuierlichen Ofen bei einer Temperatur von 1480°C. Polyacrylonitrile (1.7 dtex or 2.2 dtex) carbon precursor fibers are each impregnated with the described dispersions (1A, 1B, 1C), dried and stabilized by thermal oxidation under air atmosphere at 240-280 ° C. The resulting fibers are made into crimped staple fibers (62 mm fiber length). After carding / carding these fibers are deposited into a single or multi-ply pile and processed by one or both sides needling to a felt (basis weight of 200 to 800 g / m2). Subsequently, a carbonization under a protective gas atmosphere in a continuous furnace at a temperature of 1480 ° C.
Ein Referenzmuster ohne Zusatz von Metallverbindungen wurde in gleicher Weise karbonisiert (Vergleichsmuster 2). Als weiteres Referenzmaterial (Vergleichsmuster 1) diente ein kommerzieller, graphitierter Kohlenstofffilz Sigracell® GFD 4.6 (SGL Carbon GmbH, Meitingen) A reference pattern without addition of metal compounds was carbonized in the same way (comparative example 2). As a further reference material (comparative sample 1) used was a commercial, graphitized carbon felt Sigracell ® GFD 4.6 (SGL Carbon GmbH, Meitingen)
Ausführungsbeispiel 2 Embodiment 2
Zu einer Spinnlösung aus Polyacrylnitril und Lösungsmittel (DMF) werden 3 To a spinning solution of polyacrylonitrile and solvent (DMF) are 3
Gewichtsprozent Bismuth (lll)-oxid (nanoskalig 80-200 nm) und 1 Gewichtsprozent Indium-isopropoxid zugeben und daraus Polymerfasern durch Nasspinnen erzeugt. Nach thermischer Oxidation der Fasern unter Luftatmosphäre bei 280°C werden diese zu gekräuselten Stapelfasern verarbeitet (62 mm Faserlänge). Nach Krempeln/Kardieren werden diese Fasern zu einem ein- oder mehrlagigen Flor abgelegt und durch ein- oder beidseitige Vernadelung (Flächenmassen von 400 bis 700 g/m2) zu einem Filz verarbeitet. Anschließend erfolgt eine Karbonisierung unter Schutzgasatmosphäre in einem kontinuierlichen Ofen bei einer Temperatur von 1480°C. Weight percent bismuth (III) oxide (nanoscale 80-200 nm) and 1 weight percent indium isopropoxide and polymer fibers produced by wet spinning. After thermal oxidation of the fibers under air atmosphere at 280 ° C, these are processed into crimped staple fibers (62 mm fiber length). After carding / carding these fibers are stored in a single or multi-ply pile and by one or double-sided needling (surface masses from 400 to 700 g / m2) into a felt. Subsequently, a carbonization under a protective gas atmosphere in a continuous furnace at a temperature of 1480 ° C.
Materialanalysen material analysis
Spezifische Oberfläche (BET) wurde mittels Sorption von Krypton bestimmt (DIN-ISO 9277). Der Netzebenenenabstand (d002) und die Kristallithöhe (Lc) wurden röntgen- diffraktometrisch aus dem (002) Beugungsmaximum ermittelt (DIN EN 13925). Der spezifische elektrische Widerstand senkrecht zur Filzebene (z) wurde mittels Specific surface area (BET) was determined by sorption of krypton (DIN-ISO 9277). The lattice plane distance (d 0 02) and the crystal height (L c ) were determined by X-ray diffractometry from the (002) diffraction maximum (DIN EN 13925). The electrical resistivity perpendicular to the felt plane (z) was determined by means of
Zweipunktmessung mit Goldkontakten bei einer Kompression des Filzes von 80% der Ausgangsdicke bestimmt. Für die Materialien wurden Parameter erhalten: Two-point measurement with gold contacts determined with a compression of the felt of 80% of the initial thickness. Parameters were obtained for the materials:
Elektrochemische Prüfung Electrochemical testing
Zur Bestimmung der Elektrodeneigenschaften wurden die Filze und das Referenzmate- rial in einer Vanadium Redox Flow Batterie-Einzelzelle mit einer Elektrodenfläche von 20 cm2 untersucht. Die Materialien wurden jeweils an Anode und Kathode mit einer Kom- pression auf 75% der Ausgangsdicke verbaut. Als Separator wurde eine teilfluorierte Anionenaustauschermembran (Fumasep FAP 450, Fumatech GmbH, Bietigheim- Bissingen) und Graphit-Kompoundplatten als Stromableiter verwendet. Alle Zellprüfungen wurden mit 0,8 M Vanadium/4M Sulfat und Elektrolytflußraten von 80 mL/min durchgeführt. To determine the electrode properties, the felts and the reference material were examined in a vanadium redox flow battery single cell with an electrode area of 20 cm 2 . The materials were each attached to the anode and cathode with a installed at 75% of the original thickness. The separator used was a partially fluorinated anion exchange membrane (Fumasep FAP 450, Fumatech GmbH, Bietigheim-Bissingen) and graphite compound plates as current conductors. All cell tests were performed with 0.8 M vanadium / 4M sulfate and electrolyte flow rates of 80 mL / min.
Für jede Prüfung wurden die Zellen durch eine vollständige Ladung des Elektrolyten konditioniert. Zur Bestimmung der elektrochemischen Charakteristik der Filze wurden 3 aufeinanderfolgende Lade/Entladezyklen (Ladeschlussspannung 1,65 V, Entlade- schlußspannung 0,9 V) jeweils bei Stromdichten von 20 bis 60 mA/cm2 durchgeführt. For each test, the cells were conditioned by a full charge of the electrolyte. To determine the electrochemical characteristics of the felts, 3 consecutive charge / discharge cycles (charge end voltage 1.65 V, discharge voltage 0.9 V) were carried out in each case at current densities of 20 to 60 mA / cm 2 .
Als Kenngrößen der Zellprüfungen wurden jeweils bestimmt The parameters of the cell tests were determined in each case
„. . .. .. mittlere Entladespannung (V) ~—— ". , .. .. average discharge voltage (V) ~ -
Spannungseffizienz ην(%) = ^-^ - 100 Voltage efficiency η ν (%) = ^ - ^ - 100
mittlere Ladespannimg (V)  medium charging voltage (V)
, , ,,. . ,n / Entladekapazität (Ah) _ _ _ , ,, ,,. , , n / unloading capacity (Ah) _ _ _
Ladungseffizienz ηχ(%) = — - 100 Charge efficiency η χ (%) = - - 100
Ladekapazität (Ah)  Load capacity (Ah)
1 38 V 100 -1 38 V 100 -
Zyklenwiderstand Rz( . - cm2) Cycle resistance R z (.-Cm 2 )
Stromdichte (AI cm ) 100 + T Die Ausführungsbeispiele zeigen eine deutliche höhere Spannungseffizienz (Figur 1) und einen geringeren Zellwiderstand (erkennbar am geringeren Abfall der Spannungseffizienz mit steigender Stromdichte). Current density (AI cm) 100 + T The embodiments show a significantly higher voltage efficiency (Figure 1) and a lower cell resistance (recognizable by the lower drop in voltage efficiency with increasing current density).
Die Zyklenwiderstände wurde zu 2,9 Ohm x cm2 (Vergleichsmuster 1), 2,3 Ohm x cm2 (Vergleichsmuster 2), 2,0 Ohm x cm2 (Ausführungsbeispiel 1, Dispersion 1A) und 2,1 Ohm x cm2 (Ausführungsbeispiel 2) bestimmt. The cycles resistors was 2.9 Ohm x cm 2 (comparative sample 1), 2.3 Ohm x cm 2 (Comparative sample 2), 2.0 Ohm x cm 2 (Embodiment 1 dispersion 1A) and 2.1 Ohm x cm 2 (Embodiment 2) determined.
Darüber hinaus ist die Ladungseffizienz (Figur 2) vor allem bei niedriger Stromdichte, bei welcher infolge der Ladeschlußspannung von 1,65 V ein hoher Ladezustand (> 99%) erzielt wird, höher als bei den Vergleichsmustern. Dies deutet auf geringere parasitäre Wasserstoffentwicklung bei Verwendung der erfindungsgemäßen Filze hin. In addition, the charge efficiency (Figure 2), especially at low current density, at which as a result of the end-of-charge voltage of 1.65 V, a high state of charge (> 99%) is achieved, higher than in the comparison samples. This indicates less parasitic hydrogen evolution when using the felts of the present invention.
Legende zu den Figuren Figur 1 Legend to the figures Figure 1
(A) : Spannungseffizienz (in %) einer Vanadium Redox Flow Batterie-Einzelzelle als (A): Voltage efficiency (in%) of a vanadium redox flow battery single cell as
Funktion der Stromdichte (in mA/cm2) unter Verwendung von 2 Elektroden vom Typ Vergleichsmuster 1 Function of the current density (in mA / cm 2 ) using 2 electrodes of the type comparative sample 1
(B) : Vergleichsmuster 2  (B): Comparative Sample 2
(C) : Ausführungsbeispiel \, Dispersion 1A  (C): Embodiment 1, Dispersion 1A
(D) : Ausführungsbeispiel 2  (D): Embodiment 2
Figur 2 FIG. 2
(A) : Ladungseffizienz (in %) einer Vanadium Redox Flow Batterie-Einzelzelle als (A): Charge efficiency (in%) of a vanadium redox flow battery single cell as
Funktion der Stromdichte (in mA/cm2) unter Verwendung von 2 Elektroden vom Typ Vergleichsmuster 1 Function of the current density (in mA / cm 2 ) using 2 electrodes of the type comparative sample 1
(B) : Vergleichsmuster 2  (B): Comparative Sample 2
(C) : Ausführungsbeispiel \, Dispersion 1A  (C): Embodiment 1, Dispersion 1A
(D) : Ausführungsbeispiel 2  (D): Embodiment 2

Claims

Patentansprüche claims
1. Verfahren zur Herstellung von metalldotiertem Filz aus Kohlenstofffasern, dadurch gekennzeichnet, dass eine textile Struktur aus präoxidierten Polyacrylnitrilfasern bei Temperaturen bis 1500°C karbonisiert wird, wobei als Präkursorfasern Polyacrylnitril mit einem Metallpräkursor funktionalisiert sind. 1. A process for the production of metal-doped felt from carbon fibers, characterized in that a textile structure of pre-oxidized polyacrylonitrile fibers is carbonized at temperatures up to 1500 ° C, wherein as Präkursorfasern polyacrylonitrile are functionalized with a metal precursor.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Filz eine Dicke von 0,5 bis 10 mm aufweist. 2. The method according to claim 1, characterized in that the felt has a thickness of 0.5 to 10 mm.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Filz ein Flächengewicht von 100 bis 1000 g/m2 aufweist. 3. The method according to claim 1, characterized in that the felt has a basis weight of 100 to 1000 g / m 2 .
4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Filz eine BET-Oberfläche von 0,4 bis 10 m2/g aufweist. 4. The method according to claim 1, characterized in that the felt has a BET surface area of 0.4 to 10 m 2 / g.
5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Filz einen spezifischen elektrischen Widerstand senkrecht zur Filzrichtung von 0,5 bis 5 Ohm mm aufweist. 5. The method according to claim 1, characterized in that the felt has a specific electrical resistance perpendicular to the felt direction of 0.5 to 5 ohm mm.
6. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Filz einen Kohlenstoffgehalt von 90 bis 99% aufweist. 6. The method according to claim 1, characterized in that the felt has a carbon content of 90 to 99%.
7. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Filz einen Stickstoffanteil von 0,2 bis 5% aufweist. 7. The method according to claim 1, characterized in that the felt has a nitrogen content of 0.2 to 5%.
8. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Filz einen 8. The method according to claim 1, characterized in that the felt a
Netzebenenabstand von 3,40 bis 3,55 Angstrom aufweist. Lattice plane spacing of 3.40 to 3.55 Angstrom.
9. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Anteile an Zinn, Bismut, Mangan, Indium, Phosphor und/oder Antimon jeweils 200 bis 5000 ppm betragen. 9. The method according to claim 1, characterized in that the amounts of tin, bismuth, manganese, indium, phosphorus and / or antimony in each case be 200 to 5000 ppm.
10. Verwendung des metalldotierten Filzes hergestellt gemäß dem Verfahren nach einem oder mehrerer der vorangehenden Ansprüche zum Einsatz in einer Redox Flow Batterie. 10. Use of the metal-doped felt prepared according to the method of one or more of the preceding claims for use in a redox flow battery.
EP16731595.1A 2015-06-30 2016-06-22 Process for the preparation of carbon felt electrodes for redox flow batteries Withdrawn EP3317441A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102015212234.4A DE102015212234A1 (en) 2015-06-30 2015-06-30 Process for producing carbon felt electrodes for redox flow batteries
PCT/EP2016/064468 WO2017001264A1 (en) 2015-06-30 2016-06-22 Process for the preparation of carbon felt electrodes for redox flow batteries

Publications (1)

Publication Number Publication Date
EP3317441A1 true EP3317441A1 (en) 2018-05-09

Family

ID=56194492

Family Applications (1)

Application Number Title Priority Date Filing Date
EP16731595.1A Withdrawn EP3317441A1 (en) 2015-06-30 2016-06-22 Process for the preparation of carbon felt electrodes for redox flow batteries

Country Status (6)

Country Link
US (1) US20180127895A1 (en)
EP (1) EP3317441A1 (en)
JP (1) JP6669784B2 (en)
KR (1) KR102081006B1 (en)
DE (1) DE102015212234A1 (en)
WO (1) WO2017001264A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6855843B2 (en) * 2017-03-01 2021-04-07 三菱ケミカル株式会社 Electrodes for redox flow batteries and their manufacturing methods, and redox flow batteries
DK3439093T3 (en) * 2017-08-04 2020-04-14 Siemens Ag Redox-flow battery and method for operating a redox-flow battery
JP6859963B2 (en) * 2018-01-17 2021-04-14 トヨタ自動車株式会社 Redox flow fuel cell
KR102084947B1 (en) * 2018-11-21 2020-03-05 재단법인 한국탄소융합기술원 Method for manufacturing sliver coated carbon fiber
KR102150615B1 (en) * 2019-01-07 2020-09-01 경상대학교산학협력단 Composite sulfide/sulfur electrodes and manufacturing method thereof
CN110656403B (en) * 2019-11-07 2022-04-05 武汉纺织大学 Easily-conductive metal-doped polyacrylonitrile carbon fiber and preparation method thereof
CN111477894A (en) * 2020-05-11 2020-07-31 辽宁大学 High-activity hydrogen evolution inhibition type carbon nanofiber electrode material, preparation method thereof and application thereof in vanadium battery

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3843312A1 (en) 1988-12-22 1990-06-28 Siemens Ag Rebalance cell for a Cr/Fe redox ion storage device
JPH11317231A (en) * 1999-03-19 1999-11-16 Toyobo Co Ltd Carbon-based electrode material for electrolytic cell
JP3601581B2 (en) 1999-06-11 2004-12-15 東洋紡績株式会社 Carbon electrode material for vanadium redox flow battery
JP2001085022A (en) * 1999-09-10 2001-03-30 Toyobo Co Ltd Carbon electrode material and carbon electrode material assembly
JP2004003043A (en) * 2001-05-24 2004-01-08 Toray Ind Inc Flameproof fiber material, carbon fiber material, graphite fiber material and method for producing the same
KR101100693B1 (en) * 2009-05-18 2012-01-03 재단법인대구경북과학기술원 Metal-Impregnated Carbon Nanofibers and Preparation Method of The Same, and Fuel Cell and Filter using The Metal-Impregnated Carbon Nanofibers
CN102522568B (en) 2011-12-10 2015-06-24 中国科学院金属研究所 Method for preparing electrode material for all-vanadium flow battery
DE102012201942B8 (en) 2012-02-09 2015-02-26 Ewe-Forschungszentrum Für Energietechnologie E. V. Use of an activated carbonaceous material, method of making a carbonaceous electrode, carbonaceous electrode, use thereof, and vanadium redox flow cell
US8993183B2 (en) 2012-12-31 2015-03-31 Enervault Corporation Operating a redox flow battery with a negative electrolyte imbalance
DE102013217882A1 (en) * 2013-09-06 2015-03-12 Sgl Carbon Se Electrode substrate made of carbon fibers
US9281514B2 (en) * 2014-07-29 2016-03-08 Ford Global Technologies, Llc Batteries prepared by spinning
CN104241661B (en) * 2014-09-23 2017-04-19 中国科学院金属研究所 Preparation method for combination electrode for all-vanadium redox flow battery
CN104332638B (en) * 2014-10-20 2016-10-05 中国科学院金属研究所 The preparation method of tungsten-based catalyst used for all-vanadium redox flow battery/carbon nano-fiber combination electrode

Also Published As

Publication number Publication date
DE102015212234A1 (en) 2017-01-26
JP6669784B2 (en) 2020-03-18
KR102081006B1 (en) 2020-02-24
US20180127895A1 (en) 2018-05-10
JP2018528331A (en) 2018-09-27
WO2017001264A1 (en) 2017-01-05
KR20180019746A (en) 2018-02-26

Similar Documents

Publication Publication Date Title
EP3041989B1 (en) Electrode substrate made of carbon fibers
WO2017001264A1 (en) Process for the preparation of carbon felt electrodes for redox flow batteries
He et al. Flexible electrospun carbon nanofiber embedded with TiO2 as excellent negative electrode for vanadium redox flow battery
Di Blasi et al. Synthesis of flexible electrodes based on electrospun carbon nanofibers with Mn3O4 nanoparticles for vanadium redox flow battery application
EP2812114B1 (en) Use of mesoporous graphite particles for electrochemical applications
JP3601581B2 (en) Carbon electrode material for vanadium redox flow battery
DE112015001452B4 (en) Oxygen reduction catalyst and manufacturing method therefor
JP2955938B2 (en) Carbon-based electrode materials for electrolytic cells
Busacca et al. High performance electrospun nickel manganite on carbon nanofibers electrode for vanadium redox flow battery
DE102006050090A1 (en) Oxygen reduction gas diffusion cathode has a porous electrically conductive substrate with diamond particles with hydrophobic coatings and catalytic particles in a fluorine resin binder
DE102012201942B4 (en) Use of an activated carbonaceous material, method of making a carbonaceous electrode, carbonaceous electrode, use thereof, and vanadium redox flow cell
CN114031079A (en) Molybdenum carbide carbon nanofiber composite material and preparation method and application thereof
Kabtamu et al. BiVO4-Decorated graphite felt as highly efficient negative electrode for all-vanadium redox flow batteries
WO2015049128A1 (en) Noble metal-free catalyst system for a fuel cell
JPH11317231A (en) Carbon-based electrode material for electrolytic cell
Choi et al. Low-Index Facet Polyhedron-Shaped Binary Cerium Titanium Oxide for High-Voltage Aqueous Zinc–Vanadium Redox Flow Batteries
KR101993456B1 (en) Electrode active material for magnesium battery, method for preparing the same, electrode comprising the same, and magnesium battery comprising the electrode
Huang et al. Electrodes with metal-based electrocatalysts for redox flow batteries in a wide pH range
EP3113275B1 (en) Secondary magnesium battery and electrolyte system and electrode for a secondary magnesium battery
Bin Gah WO3/SnO2-Modified Graphite Felts as Novel Carbon-Based Positive Electrodes for Zinc-Cerium Redox-Flow Battery (RFB)
KR101993457B1 (en) Electrode active material for magnesium battery, method for preparing the same, electrode comprising the same, and magnesium battery comprising the electrode
EP2888779A1 (en) Electrode for a galvanic cell
WO2022078871A1 (en) Fuel cell membrane electrode assembly, and fuel cell
KR20240062922A (en) Non-noble metal oxide catalyst in the form of nanofiber and integrated electrode for water electrolysis using the same
DE102022122814A1 (en) ELECTROLYTE FOR METAL-AIR BATTERY

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20180130

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20220104