WO2014111273A1 - Rechargeable electric energy accumulator - Google Patents

Rechargeable electric energy accumulator Download PDF

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Publication number
WO2014111273A1
WO2014111273A1 PCT/EP2014/050020 EP2014050020W WO2014111273A1 WO 2014111273 A1 WO2014111273 A1 WO 2014111273A1 EP 2014050020 W EP2014050020 W EP 2014050020W WO 2014111273 A1 WO2014111273 A1 WO 2014111273A1
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WIPO (PCT)
Prior art keywords
oxide
storage
electrical energy
wettable
rechargeable
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PCT/EP2014/050020
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German (de)
French (fr)
Inventor
Carsten Schuh
Thomas Soller
Original Assignee
Siemens Aktiengesellschaft
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Publication of WO2014111273A1 publication Critical patent/WO2014111273A1/en

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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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/08—Hybrid cells; Manufacture thereof composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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

Definitions

  • the invention relates to a rechargeable electrical energy storage, in particular a metal oxide-air energy storage, with at least one storage element for storing electrical energy, wherein the storage element comprises a reducible in the charging operation of the energy storage and oxidizable in the discharge operation of the energy storage memory material.
  • a new example of a storage option for excess electrical energy is the use of rechargeable electrical energy absorbers in the form of metal-air energy storage devices or metal-air batteries.
  • Energy stores are based essentially on the principle of electrochemical cells, d. H . the redox-based conversion of chemical into electrical energy or vice versa.
  • oxidizing agents for example oxygen ions obtained from atmospheric oxygen, are usually formed on a positively charged (air) electrode and are arranged by means of a between the positive and a negative electrode and for the oxidizing agent, ie. H . for example B.
  • the oxygen ions formed according to permeable electrolyte fed to the negative electrode. Conversely, it is possible that the oxygen ions migrate from the negative electrode through the electrolyte to the positive (air) electrode ⁇ charging process).
  • a reaction of the oxygen ions with a gaseous redox couple ("redox shuttle"), in particular a hydrogen Water vapor mixture, instead, wherein the oxygen taken up or released by the gaseous redox pair is transferred by diffusion of the redox couple to a porous or particulate, in the charging mode of the energy storage reducible and oxidizable in the discharge operation of the energy storage memory material of a storage element.
  • Generic energy storage require for operation high temperatures in the range between 600 and 900 ° C, since only at sufficiently high temperatures, a sufficient activity or ionic conductivity of the materials used is given.
  • the problem is that the mentioned high operating temperatures as well as the repeated oxidation or reduction of the storage material favor a successive coarsening of the storage material, in particular by grain growth and sintering, which causes a noticeable aging of the power output or power consumption of the energy store.
  • the oxidation mechanism of the storage material present on the shelf as metal (reduced form) or metal oxide (oxidized form) is often based primarily on cationic diffusion.
  • the oxidation mechanism based on cationic diffusion causes a mass flow of the storage material out of the storage element Towards an oxidation source and thus contributes to a continuous change in the structure of the memory element, which manifests itself in a deterioration of the charging and discharging characteristics and the useful capacity of the energy storage.
  • the invention is therefore based on the problem to provide an improved rechargeable electrical energy storage.
  • the problem is solved by a rechargeable electrical energy store of the type mentioned above, which is characterized in that the storage element comprises a material wettable at least in sections by the reduced form of the storage material.
  • the rechargeable electrical energy store according to the invention has in the storage element, in addition to the storage material, a material that is at least partially wettable even by the form of the storage material that is reduced during the charging operation of the energy store. Consequently, the reduced form of the storage material and the material wettable by it or their surfaces interact with one another in such a way that the reduced form of the storage material wets or wets the surface of the wettable material at least in sections, preferably completely. Accordingly, during the charging process of the energy storage, d. H. upon reduction of the storage material from its oxidized to its reduced form, wetting of the wettable material with the reduced form of the storage material.
  • the storage material is usually iron or iron oxide or a mixture of iron and iron oxide.
  • the reduced form of the storage material is here elementary iron.
  • the process of wetting can be at least partially reversible. If the energy storage is thus operated in the unloading operation, d. H. As the storage material transitions from its reduced to its oxidized form, the bond formed by the wetting of the wettable material with the reduced form of the storage material can be solved. If the energy store is then operated again in the loading mode, the storage material again assumes its reduced form and the processes described above can take place again.
  • a coating or coating of the surface of the wettable material with the reduced form of the storage material results.
  • core-shell particles are formed.
  • the wettable material wetted or surrounded by the reduced form of the storage material may be regarded as a core component and the reduced form of the storage material as a shell or shell component.
  • the good wettability of the wettable material with the reduced form of the storage material is reflected by a comparatively small wetting angle.
  • the wetting angle (hereinafter also referred to as the contact angle) between two solid phases is to be understood as meaning the angle which forms a drop-shaped structure of the wetting material on the surface of the material to be wetted in thermodynamic equilibrium.
  • the size of the wetting angle depends in particular on the strength of the interactions between the surfaces or the respective surface energies of the substances. The smaller the wetting angle, the stronger the interactions.
  • the wetting angle of the reduced form of the storage material on the surface of the wettable material is below 90 °, in particular in the range of 1 to 75 °, in particular 1 to 35 °.
  • the wettable material is expediently formed from a material which has an electrically conductive or semiconducting surface and thus with the electron gas of the reduced form of the storage material, which is present in particular as a metallic form of the storage material, forming attraction or. Adhesion forces can change. This requires the good wettability of the wettable material with the reduced form of the storage material.
  • the wettable material is preferably made of an oxide-ceramic material based on cerium oxide, chromium oxide, gadolinium oxide, copper oxide, manganese oxide, titanium oxide, or a rowskit compound, preferably of the general form (RE,
  • the wettable material may in principle be formed from all, letting to be wet of the reduced form of the memory material letting materials. The selection of the wettable material is therefore expediently to be selected as a function of the specific storage material in question and its reduced form.
  • the wettable material is preferably particulate.
  • the particle-shaped, d. H . Wettable material formed from individual particles and / or particle aggregates is distributed in the matrix of the storage element in which the storage material is also distributed.
  • the wettable material obtains a particle shape in that it is shaped as a coating on a particle
  • Carrier material is applied.
  • the carrier material can be formed, for example, from a particulate, oxide-ceramic material based on aluminum oxide, calcium oxide, lanthanum oxide, magnesium oxide, ioboxide, tantalum oxide, yttrium oxide, zirconium oxide or mixtures of the aforementioned. It is crucial that between the carrier material and the enveloping this or. enclosing wettable material a stable, especially chemical, bond is ensured.
  • the carrier material may have a porous structure.
  • the storage element additionally comprises a spacer material.
  • the spacer material is not or only slightly wettable due to the reduced form of the storage material.
  • the wetting angle 1 between the reduced shape of the storage material and the surface of the spacer material is typically greater than 90 °.
  • the spacer material serves to store the storage material, i. H . in particular the reduced form of the wettable material Storage material respectively the aforementioned, formed by the wetting of the wettable material with the reduced form of the storage material core-shell particles, to separate and a Agg1ome at ion or. Coarsening or Prevent sintering of the storage material.
  • the spacer material is expediently formed from an oxide-ceramic material based on zirconium oxide, yttrium oxide and / or yttrium compounds.
  • the ⁇ bstandshaltematerial is preferably present particulate.
  • the particulate d. H . from individual particles and / or
  • Particle aggregates formed, ⁇ bstandshaltem material is distributed in the matrix of the memory element, in which the memory material and the wettable material is distributed, included.
  • the spacer material that at least a part of the spacer material obtains a particle shape in that it is applied as a coating on a particulate carrier material.
  • the carrier material can be formed, for example, from a particulate, oxide-ceramic material based on aluminum oxide, calcium oxide, lanthanum oxide, magnesium oxide, niobium oxide, tantalum oxide, yttrium oxide, zirconium oxide or mixtures of the aforementioned.
  • it is crucial that between the carrier material and the enveloping this or. enclosing ⁇ bstandshaltem material is a stable, in particular chemical, binding geric.
  • the inertial material may also have a horrorant structure here.
  • the proportion of wettable material is advantageously in the range of 30 to 10 Vo1. -%, in particular in the range of 25 to 15 Vo1. -%. In exceptional cases, the proportion of wettable material may also be lower or higher.
  • the proportion of spoke material is in the range of 30 to 90 Vo1. -%, especially above 40 vol. -%, preferably above 50 Vo1. -%.
  • the proportion of memory material may also be lower or higher.
  • the proportion of storage material essentially determines the storage capacity of the storage element and is therefore generally to be set high.
  • spacer material is also contained in the storage element in addition to the storage material and the wettable material, its proportion is in the range from 10 to 30 Vo.sub.1. %, in particular in the range of 15 to 25 vol. -%.
  • the proportion of spacer material may also be lower or higher.
  • the total amount of wettable material and spacer material should total in the range of 2 to 40 Vo1. -%, in particular in the range of 5 to 15 Vo1. -% , lie .
  • a volume fraction of open porosity must also be present in the storage element, which is in the range of 10 to 50 Vo1. -%, preferably in the range of 25 to 40 Vo1. -% should be in order to ensure the unimpeded diffusion of the redox shuttle in the storage material.
  • Energy storage arrangement be summarized. This is done in particular by a stack-like arrangement of several Energypeieher one above the other. A corresponding energy storage arrangement can be referred to as a "stack".
  • FIG. 1 is a schematic diagram of an energy storage device according to an exemplary embodiment of the invention
  • FIG. 2 is an enlarged view of that in FIG. 1
  • Fig. 1 shows a P inzipda position of an energy storage 1 according to an exemplary embodiment of the invention.
  • the energy storage 1 is designed as a metal oxide-air Ene giespeieher. Based on Fig. 1, the structure or the mode of operation of the energy storage 1 will first be described.
  • Viewed from bottom to top of the Ene gie prayer 1 comprises an interconnector plate 2, the contact webs 3 has on its underside. Through the formed by the contact webs 3 comb-like structure of the interconnector plate 2 air channels 4 are formed.
  • de interconnector plate 2 At the top of de interconnector plate 2 is connected to the contact webs 3 of the Inte konnektorplatte 2 adjacent positive electrode 5, a trained in particular as a solid electrolyte electrolyte 6 and a negative electrode 7 at.
  • the positive electrode 5 may be referred to as the air electrode, the negative electrode 7 as the storage electrode.
  • Adjacent to the top of the negative electrode 7 is a storage element 8 for storing electrical energy.
  • an interconector plate 2 again connects.
  • the structure of the energy storage 1 is repeated.
  • Via a gas supply 9 an oxygen-containing process gas, in particular air, is supplied.
  • the oxygen contained in the process gas is converted into oxygen ions (O 2 ⁇ ions) and travels from the positive electrode 5 through the electrolyte 6 to the negative electrode 7.
  • the negative electrode 7 is connected via a redox couple in the form of a gaseous hydrogen-steam mixture
  • H2 / H2O mixture with a redox-active storage material 10, such as an iron-iron oxide mixture, having memory element 8 for storing electrical energy in combination.
  • a redox-active storage material 10 such as an iron-iron oxide mixture
  • the migrated through the electrolyte 6 oxygen ions are bound to the de negative electrode 7 in steam guided through the storage element 8 after the discharge.
  • the storage material 10 is oxidized or reduced, wherein the optionally necessary oxygen can be provided by serving as a redox couple hydrogen-water vapor mixture.
  • the mechanism of oxygen transport through a redox pair is called a shuttle mechanism.
  • Oxidation process in about the same resting voltage of about 1 V has, as serving as a redox couple hydrogen-steam mixture at a partial pressure ratio of 1, otherwise there is an increased resistance to the oxygen transport through the components of the redox couple, d. H . of the hydrogen-steam mixture.
  • the diffusion of the oxygen ions through the electrolyte 6 requires a Radiotempe nature of the energy storage device 1 600-900 "C.
  • temperatures of 600 to 900 ° C for optimum composition of the hydrogen-steam mixture in equilibrium with the storage material 10 are advantageous the high operating temperatures of the Energy storage 1 are all components of the energy storage device 1, ie in particular the electrodes 5, 7 and the electrolyte 6, as well as the storage element 8 exposed to high thermal loads.
  • FIG. 2 shows an enlarged view of the storage element 8 associated with the energy store 1 shown in FIG. 1.
  • the storage element 8 has a cuboid, porous storage element body.
  • the memory element 8 represents a matrix in which a storage material 10 which can be reduced during charging operation of the energy store 1 and oxidizable in the discharge operation of the energy store 1 is contained in the form of a particulate iron-iron oxide mixture.
  • the reduced form of the storage material 10 present in the charging operation of the energy store 1 is therefore elemental iron, which in the discharge operation of the energy store 1 present oxidized form of the storage material 10 consists of at least one iron oxide compound.
  • particulate storage material 10 is in the matrix a wettable by the reduced form of the memory material 10 material 11, which z. B. from a particulate oxide ceramic based on cerium oxide, gadolinium oxide, chromium oxide, copper oxide, manganese oxide, titanium oxide or a perovskite compound, preferably of the general form (RE,
  • the wettable material 11 in FIG. 2 is wetted with the storage material 10, that is to say the wettable material 11 in FIG. H .
  • the storage material 10 encloses the wettable material 11 to form so-called core-shell particles.
  • the wettable material 11 surrounded by the reduced shape of the storage material 10 as the core component ("core") and the reduced form of the storage material 10 as a shell or shell component
  • FIG. 2 shows the state of charge or charged state of the energy store 1.
  • the wetting of the wettable material 11 with the reduced shape of the storage material 10 is possible because the wetting angle between the reduced shape of the storage material 10 and the wettable material 11 is less than 90 °.
  • the wetting angle between the reduced shape of the storage material 10 and the wettable material 11 is in the range of 5 to 75 °.
  • the process of wetting the wettable material 11 with the storage material 10 in its reduced form may be reversible so that the bond formed by wetting the reduced form of the storage material 10 on the surface of the wettable material 11 in a discharge of the Energy storage 1 can solve.
  • the spacer material 12 is z. B. in the form of particles based on yttrium oxide or yttrium-containing oxidic compounds.
  • the spacer material 12 serves to prevent the formation of particle-particle contacts of the memory material 10 and thus a possible sintering at the high temperatures required for the operation of the energy store 1. Coarsening of the memory material 10 to prevent.
  • wetting of the spacer material 12 with the storage material 10 is neither in its reduced nor oxidized form against the wetting of the wettable material 11 by the storage ial 10 favors.
  • the wetting angle between the spacer material 12 and the memory material 10 is greater than 90 °.
  • the wettable material 11 differs from the spacer material 12 substantially in terms of their Benet tion angle relative to the memory material 10 and. its reduced form.
  • Both the wettable material 11 and the ⁇ bstandshalte- material 12 may be applied in addition to the described possibility that it is itself particulate or granular, as a coating on a particulate, porous carrier material.
  • the carrier material may, for.
  • Example be formed from an oxide ceramic material based on calcium oxide, magnesium oxide, zirconium oxide, aluminum oxide, lanthanum oxide, niobium oxide or tantalum oxide or mixtures of the above.
  • the proportion of memory material 10 in the matrix of the memory element 8 is z. In the range of 30 to 90 Vo1. -%, especially above 40 Vo1. -%, preferably above 50 vol. -%.
  • the total amount of wettable material 11 and spacer material 12 is in the range of 2 to 40 Vo1 in total. -%, in particular in the range of 5 to 15 Vo1. -% , lie .
  • a volume fraction of open porosity in Speicherelement 8 is also present in the range of 10 to 50 Vo1. -%, preferably in the range of 25 to 40 vol. -%, lies.

Abstract

The invention relates to a rechargeable electric energy accumulator (1), in particular a metal oxide-air energy accumulator, comprising at least one storage element (8) for storing electrical energy, the storage element (8) comprising a storage material (10) that can be reduced when the energy accumulator (1) is charging and that can be oxidized when the energy accumulator (1) is discharging, the storage element (8) comprising a material (11) at least sections of which can be wetted as a result of the reduced form of the storage material (10).

Description

Beschreibung description
Wiederaufladbarer elektrischer Energiespeicher Die Erfindung betrifft einen wiederaufladbaren elektrischen Energiespeicher, insbesondere einen Metalloxid-Luft- Energiespeicher, mit wenigstens einem Speicherelement zur Speicherung elektrischer Energie, wobei das Speicherelement ein im Ladebetrieb des Energiespeichers reduzierbares und im Entladebetrieb des Energiespeichers oxidierbares Speichermaterial umfasst. The invention relates to a rechargeable electrical energy storage, in particular a metal oxide-air energy storage, with at least one storage element for storing electrical energy, wherein the storage element comprises a reducible in the charging operation of the energy storage and oxidizable in the discharge operation of the energy storage memory material.
Es sind verschiedene technische Lösungen für die Speicherung von überschüssiger elektrischer Energie, die beispielsweise durch erneuerbare Energiequellen oder durch Kraftwerke erzeugt wird und für welche temporär kein Bedarf besteht, bekannt . Ein neues Beispiel für eine Speichermöglichkeit überschüssiger elektrischer Energie ist die Verwendung von wiederaufladbaren elektrischen Energiespeiehern in Form von Me- tall -Luft-Energiespeichern bzw. Metall-Luft-Batterien . Energiespeicher basieren im Wesentlichen auf dem Prinzip elektrochemischer Zellen, d . h . der redoxbasierten Umsetzung von chemischer in elektrische Energie oder umgekehrt . Dabei werden beim Entladevorgang üblicherweise an einer positiv gela- denen (luft-) Elektrode Oxidationsmittel , beispielsweise aus Luftsauerstoff gewonnene Sauerstoffionen, gebildet und durch einen zwischen der positiven und einer negativen Elektrode angeordneten und für das Oxidationsmittel , d . h . z . B . die gebildeten Sauerstoffionen, entsprechend durchlässigen Elekt- rolyten der negativen Elektrode zugeführt . Umgekehrt ist es möglich, dass die Sauerstoffionen von der negativen Elektrode durch den Elektrolyten zu der positiven (Luft-) Elektrode wandern { Ladevorgang) . An der negativen Elektrode findet, je nachdem, ob ein Lade- oder Entladevorgang des EnergieSpeichers erfolgt , eine Reaktion der Sauerstoffionen mit einem gasförmigen Redoxpaar („Redox-Shuttle" ) , insbesondere einem Wasserstoff- Wasserdampf-Gemisch, statt, wobei der von dem gasförmigen Re- doxpaar aufgenommene oder abgegebene Sauerstoff durch Diffusion des Redoxpaares auf ein poröses bzw. partikelförmiges, im Ladebetrieb des Energiespeichers reduzierbares und im Ent- ladebetrieb des Energiespeichers oxidierbares Speichermaterial eines Speicherelements übertragen wird. There are various technical solutions for the storage of excess electrical energy, which is generated for example by renewable energy sources or power plants and for which there is no temporary need known. A new example of a storage option for excess electrical energy is the use of rechargeable electrical energy absorbers in the form of metal-air energy storage devices or metal-air batteries. Energy stores are based essentially on the principle of electrochemical cells, d. H . the redox-based conversion of chemical into electrical energy or vice versa. During the discharge process, oxidizing agents, for example oxygen ions obtained from atmospheric oxygen, are usually formed on a positively charged (air) electrode and are arranged by means of a between the positive and a negative electrode and for the oxidizing agent, ie. H . for example B. the oxygen ions formed, according to permeable electrolyte fed to the negative electrode. Conversely, it is possible that the oxygen ions migrate from the negative electrode through the electrolyte to the positive (air) electrode {charging process). At the negative electrode, depending on whether charging or discharging of the energy storage takes place, a reaction of the oxygen ions with a gaseous redox couple ("redox shuttle"), in particular a hydrogen Water vapor mixture, instead, wherein the oxygen taken up or released by the gaseous redox pair is transferred by diffusion of the redox couple to a porous or particulate, in the charging mode of the energy storage reducible and oxidizable in the discharge operation of the energy storage memory material of a storage element.
Gattungsgemäße Energiespeicher erfordern für den Betrieb hohe Temperaturen im Bereich zwischen 600 und 900° C, da erst bei entsprechend hohen Temperaturen eine hinreichende Aktivität bzw. Ionenleitfähigkeit der eingesetzten Materialien gegeben ist . Generic energy storage require for operation high temperatures in the range between 600 and 900 ° C, since only at sufficiently high temperatures, a sufficient activity or ionic conductivity of the materials used is given.
Problematisch ist, dass die genannten hohen Betriebstempe a- turen sowie die wiederholt stattfindende Oxidation bzw. Reduktion des Speichermaterials eine sukzessive Vergröberung des Speichermaterials, insbesondere durch Kornwachstum und VerSinterung, begünstigen, was eine merkliche Alterung der Leistungsabgabe bzw. Leistungsaufnahme des Energiespeichers bedingt. The problem is that the mentioned high operating temperatures as well as the repeated oxidation or reduction of the storage material favor a successive coarsening of the storage material, in particular by grain growth and sintering, which causes a noticeable aging of the power output or power consumption of the energy store.
Problematisch ist ferner, dass der Oxidationsmechanismus der in der Regal als Metall (reduzierte Form) bzw. Metalloxid (oxidierte Form) vorliegenden Speichermaterials häufig vor- wiegend auf kationischer Diffusion beruht.. Der auf kationischer Diffusion beruhende Oxidationsmechanismus bedingt einen Massefluss des Speichermaterials aus dem Speicherelement hin zu einer Oxidationsquelle und trägt somit zu einer kontinuierlichen Veränderung der Struktur des Speicherelements bei, was sich in einer Verschlechterung der Lade- und Entladecharakteristik sowie der Nutzkapazität des Energiespeichers äußert. It is also problematic that the oxidation mechanism of the storage material present on the shelf as metal (reduced form) or metal oxide (oxidized form) is often based primarily on cationic diffusion. The oxidation mechanism based on cationic diffusion causes a mass flow of the storage material out of the storage element Towards an oxidation source and thus contributes to a continuous change in the structure of the memory element, which manifests itself in a deterioration of the charging and discharging characteristics and the useful capacity of the energy storage.
Der Erfindung liegt daher das Problem zugrunde, einen verbes- serten wiederaufladbaren elektrischen Energiespeicher anzugeben . Das Problem wird erfindungsgemäß durch einen wiederaufladbaren elektrischen Energiespeicher der eingangs genannten Art gelöst, welcher sich dadurch auszeichnet, dass das Speicherelement ein durch die reduzierte Form des Speichermaterials zumindest abschnittsweise benetzbares Material umfasst. The invention is therefore based on the problem to provide an improved rechargeable electrical energy storage. According to the invention, the problem is solved by a rechargeable electrical energy store of the type mentioned above, which is characterized in that the storage element comprises a material wettable at least in sections by the reduced form of the storage material.
Der erfindungsgemäße wiederaufladbare elektrische Energiespeicher, im Weiteren kurz als Energiespeicher bezeichnet, weist in dem Speicherelement neben dem Speichermaterial ein selbst von der im Ladebetrieb des Energiespeichers reduzierten Form des Speichermaterials zumindest abschnittsweise benetzbares Material auf . Mithin wechselwirken die reduzierte Form des Speichermaterials und das von dieser benetzbare Material respektive deren Oberflächen derart miteinander, dass die reduzierte Form des Speichermaterials die Oberfläche des benetzbaren Materials zumindest abschnittsweise, bevorzugt vollständig, benetzt bzw. umschließt. Dementsprechend erfolgt während des Ladevorgangs des Energiespeichers, d. h. bei Reduktion des Speichermaterials von seiner oxidierten in seine reduzierte Form, eine Benetzung des benetzbaren Materials mit der reduzierten Form des Speichermaterials. Bei dem Speichermaterial handelt es sich üblicherweise um Eisen bzw. Eisenoxid bzw. eine Mischung von Eisen und Eisenoxid . Die reduzierte Form des Speichermaterials ist hier elementares Eisen. The rechargeable electrical energy store according to the invention, hereinafter referred to as energy store, has in the storage element, in addition to the storage material, a material that is at least partially wettable even by the form of the storage material that is reduced during the charging operation of the energy store. Consequently, the reduced form of the storage material and the material wettable by it or their surfaces interact with one another in such a way that the reduced form of the storage material wets or wets the surface of the wettable material at least in sections, preferably completely. Accordingly, during the charging process of the energy storage, d. H. upon reduction of the storage material from its oxidized to its reduced form, wetting of the wettable material with the reduced form of the storage material. The storage material is usually iron or iron oxide or a mixture of iron and iron oxide. The reduced form of the storage material is here elementary iron.
Der Prozess der Benetzung kann zumindest zum Teil reversibel sein. Wenn der Energiespeicher also im Entladebetrieb betrieben wird, d. h. das Speichermaterial von seiner reduzierten in die oxidierte Form übergeht, kann die durch die Benetzung des benetzbaren Materials mit der reduzierten Form des Speichermaterials gebildete Bindung gelöst werden. Wird der Energiespeicher sodann wieder im Ladebetrieb betrieben, nimmt das Speichermaterial wieder seine reduzierte Form ein und die oben beschriebenen Prozesse können erneut stattfinden. The process of wetting can be at least partially reversible. If the energy storage is thus operated in the unloading operation, d. H. As the storage material transitions from its reduced to its oxidized form, the bond formed by the wetting of the wettable material with the reduced form of the storage material can be solved. If the energy store is then operated again in the loading mode, the storage material again assumes its reduced form and the processes described above can take place again.
Erfindungsgemäß ergibt sich demnach eine Beschichtung bzw. Umhüllung der Oberfläche des benetzbaren Materials mit der reduzierten Form des Speichermaterials. Es können dabei, eine vollständige Benetzung bzw. Umhüllung des benetzbaren Materials mit der reduzierten Form des Speichermaterials vorausgesetzt, so genannte Core-Shell-Partikel gebildet we den . Hierbei kann das von der reduzierten Form des Speichermaterials benetzte bzw. umgebene benetzbare Material als Kernkomponente („core" ) und die reduzierte Form des Speichermaterials als Schalen- oder Hüllenkomponente („shell") betrachtet werden. Accordingly, according to the invention, a coating or coating of the surface of the wettable material with the reduced form of the storage material results. There can be, one assuming complete wetting or encasing of the wettable material with the reduced form of the storage material, so-called core-shell particles are formed. Here, the wettable material wetted or surrounded by the reduced form of the storage material may be regarded as a core component and the reduced form of the storage material as a shell or shell component.
Die gute Benetzbarkeit des benetzbaren Materials mit der re- duzierten Form des Speichermaterials zeigt sich durch einen vergleichsweise kleinen Benetzungswinkel . Unter dem Benet- zungswinkel (im Weiteren auch als Kontaktwinkel bezeichnet) zwischen zwei festen Phasen sei der Winkel zu verstehen, de nein tropfenförmiges Gebilde des benetzenden Materials auf der Oberfläche des zu benetzenden Materials im thermodynami- schen Gleichgewicht formt. Die Größe des Benetzungswinkels hängt insbesondere von der Stärke der Wechselwirkungen zwischen den Oberflächen bzw. den jeweiligen Oberflächenenergien der Stoffe ab. Je kleiner der Benetzungswinkel ist, desto stärker sind die Wechselwirkungen . The good wettability of the wettable material with the reduced form of the storage material is reflected by a comparatively small wetting angle. The wetting angle (hereinafter also referred to as the contact angle) between two solid phases is to be understood as meaning the angle which forms a drop-shaped structure of the wetting material on the surface of the material to be wetted in thermodynamic equilibrium. The size of the wetting angle depends in particular on the strength of the interactions between the surfaces or the respective surface energies of the substances. The smaller the wetting angle, the stronger the interactions.
Der Benetzungswinkel der reduzierten Form des Speichermaterials auf der Oberfläche des benetzbaren Materials liegt unterhalb 90°, insbesondere im Bereich von 1 bis 75°, insbesondere 1 bis 35°. The wetting angle of the reduced form of the storage material on the surface of the wettable material is below 90 °, in particular in the range of 1 to 75 °, in particular 1 to 35 °.
Das benetzbare Material ist zweckmäßig aus einem Werkstoff gebildet, der eine elektrisch leitende oder halbleitende Oberfläche aufweist und so mit dem Elektronengas der redu- zierten Form des Speichermaterials, welche insbesondere als metallische Form des Speichermaterials vorliegt, unter Ausbildung von Anziehungs- bzw . Adhäsionskräften Wechselwi ken kann. Dies bedingt die gute Benetzbarkeit des benetzbaren Materials mit der reduzierten Form des Speichermaterials. The wettable material is expediently formed from a material which has an electrically conductive or semiconducting surface and thus with the electron gas of the reduced form of the storage material, which is present in particular as a metallic form of the storage material, forming attraction or. Adhesion forces can change. This requires the good wettability of the wettable material with the reduced form of the storage material.
Das benetzbare Material ist bevorzugt aus einem oxidkeramischen Material basierend auf Ceroxid, Chromoxid, Gadoliniumoxid, Kupferoxid, Manganoxid, Titanoxid, oder einer Pe- rowskitVerbindung, bevorzugt der allgemeinen Form (RE, The wettable material is preferably made of an oxide-ceramic material based on cerium oxide, chromium oxide, gadolinium oxide, copper oxide, manganese oxide, titanium oxide, or a rowskit compound, preferably of the general form (RE,
AE) (Fe, Ti, Cr, Mn, Co, Ni ) O3, z. B. aus dem Kompositionsfeldern (Sr, Y) Ti03 oder (La, Ca, Sr, CE) (Fe, Ti, Cr) 03, oder Mi¬ schungen der Genannten gebildet . Die Aufzählung ist lediglich beispielhaft , das benetzbare Material kann grundsätzlich aus sämtlichen, sich gut von der reduzierten Form des Speichermaterials benetzen lassenden Materialien gebildet sein . Die Auswahl des benetzbaren Materials ist sonach zweckmäßig in Abhängigkeit des konkret vorliegenden Speichermaterials re- spektive dessen reduzierter Form zu wählen . AE) (Fe, Ti, Cr, Mn, Co, Ni) O3, e.g. B. from the composition fields (Sr, Y) Ti0 3 or (La, Ca, Sr, CE) (Fe, Ti, Cr) 0 3 , or Mi ¬ mixtures of the aforementioned formed. The list is merely exemplary, the wettable material may in principle be formed from all, letting to be wet of the reduced form of the memory material letting materials. The selection of the wettable material is therefore expediently to be selected as a function of the specific storage material in question and its reduced form.
Das benetzbare Material liegt bevorzugt partikel förmig vor . Das partikel förmige, d . h . aus einzelnen Partikeln und/oder Partikelaggregaten gebildete, benetzbare Material ist dabei in der Matrix des Speicherelements, in welchem auch das Speichermaterial verteilt enthalten ist, verteilt enthalten . The wettable material is preferably particulate. The particle-shaped, d. H . Wettable material formed from individual particles and / or particle aggregates is distributed in the matrix of the storage element in which the storage material is also distributed.
Alternativ oder ergänzend ist es denkbar, dass zumindest ein Teil des benetzbaren Materials eine Partikelform dadurch er- hält, dass es als Beschichtung auf einem partikel förmigenAlternatively or additionally, it is conceivable that at least part of the wettable material obtains a particle shape in that it is shaped as a coating on a particle
Trägermaterial aufgebracht ist . Das Trägermaterial kann beispielsweise aus einem partikel förmigen, oxidkeramischen Material basierend auf Aluminiumoxid, Kalziumoxid, Lanthanoxid, Magnesiumoxid, ioboxid, Tantaloxid, Yttriumoxid, Zirkonium- oxid oder Mischungen der Genannten gebildet sein . Entscheidend ist, dass zwischen dem Trägermaterial und dem dieses umhüllenden bzw . umschließenden benetzbaren Material eine stabile, insbesondere chemische, Bindung gewährleistet ist . Das Trägermaterial kann eine poröse Struktur aufweisen . Carrier material is applied. The carrier material can be formed, for example, from a particulate, oxide-ceramic material based on aluminum oxide, calcium oxide, lanthanum oxide, magnesium oxide, ioboxide, tantalum oxide, yttrium oxide, zirconium oxide or mixtures of the aforementioned. It is crucial that between the carrier material and the enveloping this or. enclosing wettable material a stable, especially chemical, bond is ensured. The carrier material may have a porous structure.
Vorteilhaft umfasst das Speicherelement zusätzlich ein Ab- standshaltematerial . Das Abstandshaltematerial ist durch die reduzierte Form des Speichermaterials nicht oder nur schlecht benetzbar . Der Benet zungswinke1 zwischen der reduzierten Form des Speichermaterials und der Oberfläche des Abstandshaltema- terials ist typischerweise größer als 90 ° . Das Abstandshaltematerial dient dazu, das Speichermaterial , d . h . insbesondere die das benetzbare Material umschließende reduzierte Form des Speichermaterials respektive die vorgenannten, durch die Benetzung des benetzbaren Materials mit der reduzierten Form des Speichermaterials gebildeten Core-Shell-Partikel , zu separieren und eine Agg1ome at ion bzw . Vergröberung bzw . Ve - sinterung des Speichermaterials zu verhindern. Advantageously, the storage element additionally comprises a spacer material. The spacer material is not or only slightly wettable due to the reduced form of the storage material. The wetting angle 1 between the reduced shape of the storage material and the surface of the spacer material is typically greater than 90 °. The spacer material serves to store the storage material, i. H . in particular the reduced form of the wettable material Storage material respectively the aforementioned, formed by the wetting of the wettable material with the reduced form of the storage material core-shell particles, to separate and a Agg1ome at ion or. Coarsening or Prevent sintering of the storage material.
Das Äbstandshaltematerial ist zweckmäßig aus einem oxidkeramischen Material basierend auf Zirkoniumoxid, Yttriumoxid und/oder Yttriumverbindungen gebildet. The spacer material is expediently formed from an oxide-ceramic material based on zirconium oxide, yttrium oxide and / or yttrium compounds.
Das Äbstandshaltematerial liegt bevorzugt partikelförmig vor. Das partikelformige, d. h . aus einzelnen Partikeln und/oderThe Äbstandshaltematerial is preferably present particulate. The particulate, d. H . from individual particles and / or
Partikelaggregaten gebildete, Äbstandshaltematerial ist dabei in der Matrix des Speicherelements, in welchem auch das Spei- chermaterial sowie das benetzbare Material verteilt enthalten ist, verteilt enthalten . Particle aggregates formed, Äbstandshaltem material is distributed in the matrix of the memory element, in which the memory material and the wettable material is distributed, included.
Alternativ oder ergänzend ist es auch für das Äbstandshaltematerial denkbar, dass zumindest ein Teil des Abstandshalte- materials eine Partikelform dadurch erhält, dass es als Be- schichtung auf einem partikelförmigen Trägermaterial aufgebracht ist. Das Trägermaterial kann beispielsweise aus einem partikelförmigen, oxidkeramischen Material basierend auf Aluminiumoxid, Kalziumoxid, Lanthanoxid, Magnesiumoxid, Niob- oxid, Tantaloxid, Yttriumoxid, Zirkoniumoxid oder Mischungen der Genannten gebildet sein . Auch hier ist entscheidend, dass zwischen dem Trägermaterial und dem dieses umhüllenden bzw . umschließenden Äbstandshaltematerial eine stabile, insbesondere chemische, Bindung gewäh leistet ist. Das Träge mate ial kann auch hie eine po öse Struktu aufweisen . Alternatively or additionally, it is also conceivable for the spacer material that at least a part of the spacer material obtains a particle shape in that it is applied as a coating on a particulate carrier material. The carrier material can be formed, for example, from a particulate, oxide-ceramic material based on aluminum oxide, calcium oxide, lanthanum oxide, magnesium oxide, niobium oxide, tantalum oxide, yttrium oxide, zirconium oxide or mixtures of the aforementioned. Here, too, it is crucial that between the carrier material and the enveloping this or. enclosing Äbstandshaltem material is a stable, in particular chemical, binding gewäh. The inertial material may also have a poignant structure here.
Innerhalb des Speicherelements liegt der Anteil an benetzbarem Material vorteilhaft im Bereich von 30 bis 10 Vo1. - % , insbesondere im Bereich von 25 bis 15 Vo1. - % . In Ausnahmen kann der Anteil an benetzbarem Material auch tiefer oder höher liegen . Der Anteil an Speiche mate ial liegt im Bereich von 30 bis 90 Vo1. -% , insbesondere oberhalb 40 Vol . -%, bevorzugt oberhalb 50 Vo1. -% . Gegebenenfalls kann der Anteil an Speichermaterial auch tiefer oder höher liegen . Der Anteil an Speichermaterial bestimmt wesentlich die Speicherkapazität des Speicherelements und ist deshalb grundsätzlich hoch anzusetzen . Within the storage element, the proportion of wettable material is advantageously in the range of 30 to 10 Vo1. -%, in particular in the range of 25 to 15 Vo1. -%. In exceptional cases, the proportion of wettable material may also be lower or higher. The proportion of spoke material is in the range of 30 to 90 Vo1. -%, especially above 40 vol. -%, preferably above 50 Vo1. -%. Optionally, the proportion of memory material may also be lower or higher. The proportion of storage material essentially determines the storage capacity of the storage element and is therefore generally to be set high.
Sofern in bevorzugter Ausführungsform in dem Speicherelernent neben dem Speichermaterial und dem benetzbaren Material auch Abstandshaltematerial enthalten ist , liegt dessen Anteil im Bereich von 10 bis 30 Vo1. -% , insbesondere im Bereich von 15 bis 25 Vol . -% . Gegebenenfalls kann der Anteil an Abstandshaltematerial auch tiefer oder höher liegen . Der Gesamtanteil an benetzbarem Material und Abstandshaltematerial sollte in Summe im Bereich von 2 bis 40 Vo1. -% , insbesondere im Bereich von 5 bis 15 Vo1. -% , liegen . If, in a preferred embodiment, spacer material is also contained in the storage element in addition to the storage material and the wettable material, its proportion is in the range from 10 to 30 Vo.sub.1. %, in particular in the range of 15 to 25 vol. -%. Optionally, the proportion of spacer material may also be lower or higher. The total amount of wettable material and spacer material should total in the range of 2 to 40 Vo1. -%, in particular in the range of 5 to 15 Vo1. -% , lie .
Neben dem Speichermaterial , dem benetzbaren Material und dem Abstandshaltematerial ist ferner ein Volumenanteil an offener Porosität in dem Speicherelernent vorzuhalten, der im Bereich von 10 bis 50 Vo1. -% , bevorzugt im Bereich von 25 bis 40 Vo1. -% liegen sollte, um die ungehinderte Diffusion des Re- dox-Shuttles im Speichermaterial sicherzustellen. In addition to the storage material, the wettable material and the spacer material, a volume fraction of open porosity must also be present in the storage element, which is in the range of 10 to 50 Vo1. -%, preferably in the range of 25 to 40 Vo1. -% should be in order to ensure the unimpeded diffusion of the redox shuttle in the storage material.
Selbstverständlich sind die Anteile der in dem Speicherelement enthaltenen Komponenten derart abgestimmt, dass sich in Summe ein Anteil von 100 Vo1. -% einstellt . Mehrere erfindungsgemäße Energiespeieher können zu einerOf course, the proportions of the components contained in the memory element are tuned such that a total of 100 Vo1. -% setting. Several Energiepeieher invention can to a
Energiespeicheranordnung zusammengefasst sein . Dies erfolgt insbesondere durch eine stapelartig miteinander verbundene Anordnung mehrerer Energiespeieher übereinander . Eine entsprechende Energiespeicheranordnung kann als „Stack" bezeich- net werden . Energy storage arrangement be summarized. This is done in particular by a stack-like arrangement of several Energiepeieher one above the other. A corresponding energy storage arrangement can be referred to as a "stack".
Weitere Merkmale und weitere vorteilhafte Äusgestaltungsfor- men der Erfindung sind anhand der folgenden Figuren näher er- läutert. Hierbei handelt es sich lediglich um beispielhafte Ausgestaltungsformen, die keine Einschränkung des Schutzum- fangs darstellen. Dabei zeigen: Fig. 1 eine Prinzipdarstellung eines EnergieSpeichers gemäß einer beispielhaften Aus führungsform der Erfin dung und Further features and further advantageous embodiments of the invention are described in more detail with reference to the following figures. purifies. These are merely exemplary embodiments that do not limit the scope of protection. 1 is a schematic diagram of an energy storage device according to an exemplary embodiment of the invention
Figur 2 eine vergrößerte Darstellung des dem in Figur 1 FIG. 2 is an enlarged view of that in FIG. 1
dargestellten Ene giespeieher zugehörigen Speicher elements .  shown Ene giespeieher associated memory elements.
Fig. 1 zeigt eine P inzipda stellung eines Ene gieSpeichers 1 gemäß einer beispielhaften Ausführungsform der Erfindung . Der Energiespeicher 1 ist als Metalloxid-Luft-Ene giespeieher ausgebildet . Auf Grundlage von Fig . 1 soll zunächst der Aufbau bzw. die Funktionsweise des Ene gieSpeichers 1 beschrieben werden . Von unten nach oben betrachtet umfasst der Ene giespeicher 1 eine Interkonnektorplatte 2 , die an ihrer Unterseite Kontaktstege 3 aufweist . Durch die durch die Kontaktstege 3 gebildete kammartige Struktur der Interkonnektorplatte 2 sind Luft- kanäle 4 gebildet . Fig. 1 shows a P inzipda position of an energy storage 1 according to an exemplary embodiment of the invention. The energy storage 1 is designed as a metal oxide-air Ene giespeieher. Based on Fig. 1, the structure or the mode of operation of the energy storage 1 will first be described. Viewed from bottom to top of the Ene giespeicher 1 comprises an interconnector plate 2, the contact webs 3 has on its underside. Through the formed by the contact webs 3 comb-like structure of the interconnector plate 2 air channels 4 are formed.
An die Oberseite de Interkonnektorplatte 2 schließt sich eine an die Kontaktstege 3 der Inte konnektorplatte 2 angrenzende positive Elektrode 5, ein insbesondere als Festkörperelektrolyt ausgebildeter Elektrolyt 6 sowie eine negative Elektrode 7 an . Die positive Elektrode 5 kann als Luftelektrode, die negative Elektrode 7 als Speicherelekt ode bezeichnet werden . An die Oberseite der negativen Elektrode 7 grenzt ein Speicherelement 8 zur Speicherung elektrischer Energie an. An das Speiche elernent 8 schließt wiede eine Interkon- nektorplatte 2 an . De Aufbau des EnergieSpeichers 1 wiederholt sich sonach . Über eine Gaszufuhr 9 wird ein Sauerstoff enthaltendes Prozessgas, insbesondere Luft, zugeführt. Der in dem Prozessgas enthaltene Sauerstoff wird in Sauerstoffionen (02~-lonen) umgewandelt und wandert von der positiven Elektrode 5 durch den Elektrolyten 6 zu der negativen Elektrode 7. At the top of de interconnector plate 2 is connected to the contact webs 3 of the Inte konnektorplatte 2 adjacent positive electrode 5, a trained in particular as a solid electrolyte electrolyte 6 and a negative electrode 7 at. The positive electrode 5 may be referred to as the air electrode, the negative electrode 7 as the storage electrode. Adjacent to the top of the negative electrode 7 is a storage element 8 for storing electrical energy. To the spoke element 8, an interconector plate 2 again connects. The structure of the energy storage 1 is repeated. Via a gas supply 9, an oxygen-containing process gas, in particular air, is supplied. The oxygen contained in the process gas is converted into oxygen ions (O 2 ~ ions) and travels from the positive electrode 5 through the electrolyte 6 to the negative electrode 7.
Die negative Elektrode 7 steht über ein Redoxpaar etwa in Form eines gasförmigen Wasserstoff-Wasserdampf-Gemisches The negative electrode 7 is connected via a redox couple in the form of a gaseous hydrogen-steam mixture
(H2/H2O-Gemisch) mit dem ein redoxaktives Speichermaterial 10, etwa ein Eisen-Eisenoxid-Gemisch, aufweisenden Speicherelement 8 zu Speicherung elektrischer Energie in Verbindung . (H2 / H2O mixture) with a redox-active storage material 10, such as an iron-iron oxide mixture, having memory element 8 for storing electrical energy in combination.
Die durch den Elektrolyten 6 gewanderten Sauerstoffionen werden nach der Entladung an de negativen Elektrode 7 gebunden in Wasserdampf durch das Speicherelement 8 geführt . Je nachdem, ob ein Entlade- oder Ladevorgang des EnergieSpeichers 1 gegeben ist, wird das Speichermaterial 10, oxidiert oder reduziert, wobei der gegebenenfalls notwendige Sauerstoff durch das als Redoxpaar dienende Wasserstoff-Wasserdampf-Gemisch bereitgestellt werden kann . Der Mechanismus des Sauerstoff- transports über ein Redoxpaar wird als Shuttlemechanismus bezeichnet . The migrated through the electrolyte 6 oxygen ions are bound to the de negative electrode 7 in steam guided through the storage element 8 after the discharge. Depending on whether a discharge or charging of the energy storage 1 is given, the storage material 10 is oxidized or reduced, wherein the optionally necessary oxygen can be provided by serving as a redox couple hydrogen-water vapor mixture. The mechanism of oxygen transport through a redox pair is called a shuttle mechanism.
Der Vorteil der Verwendung von Eisen als Speichermaterial 10 des Speicherelernents 8 liegt darin, dass Eisen bei seinemThe advantage of using iron as the storage material 10 of the Speicherelernents 8 is that iron in his
Oxidationsprozess in etwa dieselbe RuheSpannung von etwa 1 V aufweist, wie das als Redoxpaar dienende Wasserstoff- Wasserdampf-Gemisch bei einem PartialdruckVerhältnis von 1, andernfalls ergibt sich ein erhöhter Widerstand für den Sau- erstofftransport durch die Komponenten des Redoxpaares, d . h . des Wasserstoff-Wasserdampf-Gemisches . Oxidation process in about the same resting voltage of about 1 V has, as serving as a redox couple hydrogen-steam mixture at a partial pressure ratio of 1, otherwise there is an increased resistance to the oxygen transport through the components of the redox couple, d. H . of the hydrogen-steam mixture.
Die Diffusion der Sauerstoffionen durch den Elektrolyten 6 benötigt eine Betriebstempe atur des Energiespeichers 1 von 600 bis 900 "C. Gleichermaßen sind Temperaturen von 600 bis 900 °C für eine optimale Zusammensetzung des Wasserstoff- Wasserdampf-Gemisches im Gleichgewicht mit dem Speichermaterial 10 vorteilhaft . Durch die hohen Betriebstemperaturen des Energiespeichers 1 sind sämtliche Komponenten des Energiespeichers 1, d. h. insbesondere die Elektroden 5, 7 und der Elektrolyt 6, wie auch das Speicherelement 8 hohen thermischen Belastungen ausgesetzt . The diffusion of the oxygen ions through the electrolyte 6 requires a Betriebstempe nature of the energy storage device 1 600-900 "C. Similarly, temperatures of 600 to 900 ° C for optimum composition of the hydrogen-steam mixture in equilibrium with the storage material 10 are advantageous the high operating temperatures of the Energy storage 1 are all components of the energy storage device 1, ie in particular the electrodes 5, 7 and the electrolyte 6, as well as the storage element 8 exposed to high thermal loads.
Fig . 2 zeigt eine vergrößerte Darstellung des dem in Figur 1 dargestellten Energiespeicher 1 zugehörigen Speicherelernents 8. Das Speicherelernent 8 weist einen quaderförmigen, porösen Speicherelementkörper auf . Das Speicherelement 8 stellt eine Matrix dar, in welcher ein im Ladebetrieb des Energiespeichers 1 reduzierbares und im Entladebetrieb des Energiespeichers 1 oxidierbares Speichermaterial 10 in Form eines parti- kulären Eisen-Eisenoxid-Gemisches enthalten ist . Die im Lade- betrieb des Energiespeichers 1 vorliegende reduzierte Form des Speichermaterials 10 ist sonach elementares Eisen, die im Entladebetrieb des Energiespeichers 1 vorliegende oxidierte Form des Speichermaterials 10 besteht sonach aus zumindest einer Eisenoxidverbindung . Neben dem partikulären Speichermaterial 10 befindet sich in der Matrix ein von der reduzierten Form des Speichermaterials 10 benetzbares Material 11 , welches z . B . aus einer partikel- förmigen Oxidkeramik auf Basis von Ceroxid, Gadoliniumoxid, Chromoxid, Kupferoxid, Manganoxid, Titanoxid oder einer Pe- rowskitVerbindung, bevorzugt der allgemeinen Form (RE, Fig. FIG. 2 shows an enlarged view of the storage element 8 associated with the energy store 1 shown in FIG. 1. The storage element 8 has a cuboid, porous storage element body. The memory element 8 represents a matrix in which a storage material 10 which can be reduced during charging operation of the energy store 1 and oxidizable in the discharge operation of the energy store 1 is contained in the form of a particulate iron-iron oxide mixture. The reduced form of the storage material 10 present in the charging operation of the energy store 1 is therefore elemental iron, which in the discharge operation of the energy store 1 present oxidized form of the storage material 10 consists of at least one iron oxide compound. In addition to the particulate storage material 10 is in the matrix a wettable by the reduced form of the memory material 10 material 11, which z. B. from a particulate oxide ceramic based on cerium oxide, gadolinium oxide, chromium oxide, copper oxide, manganese oxide, titanium oxide or a perovskite compound, preferably of the general form (RE,
AE) ( Fe, Ti , Cr, Mn, Co, Ni ) O3, z . B . aus den Kompositionsfel- dern (Sr, Y) T1O3 oder (La, Ca, Sr, Ce) (Fe, Ti, Cr) 03 oder Mischungen der Genannten gebildet ist . Ersichtlich ist das benetzbare Material 11 in Figur 2 mit dem Speichermaterial 10 benetzt, d . h . das Speichermaterial 10 umschließt das benetzbare Material 11 unter Ausbildung so genannter Core-Shell-Partikel . Dabei kann das von der reduzierten Form des Speichermaterials 10 umgebene benetzbare Materi- al 11 als Kernkomponente („core" ) und die reduzierte Form des Speichermaterials 10 als Schalen- oder Hüllenkomponente AE) (Fe, Ti, Cr, Mn, Co, Ni) O 3 , e.g. B. from the Kompositionsfel- springs (Sr, Y) T1O 3 or (La, Ca, Sr, Ce) (Fe, Ti, Cr) 0 3 or mixtures thereof is formed. Obviously, the wettable material 11 in FIG. 2 is wetted with the storage material 10, that is to say the wettable material 11 in FIG. H . the storage material 10 encloses the wettable material 11 to form so-called core-shell particles. In this case, the wettable material 11 surrounded by the reduced shape of the storage material 10 as the core component ("core") and the reduced form of the storage material 10 as a shell or shell component
(„shell"} betrachtet werden . Figur 2 zeigt demnach den Ladezustand bzw . geladenen Zustand des Energiespeichers 1. Die Benetzung des benetzbaren Materials 11 mit der reduzierten Form des Speichermaterials 10 ist deshalb möglich, da der Benetzungswinkel zwischen der reduzierten Form des Speicher- materials 10 und dem benetzbaren Material 11 geringer als 90° ist . Insbesondere liegt der Benet zungswinkel zwischen der reduzierten Form des Speichermaterials 10 und dem benetzbaren Material 11 im Bereich von 5 bis 75° . Der Prozess der Benetzung des benetzbaren Materials 11 mit dem Speichermate ial 10 in seiner reduzierten Form kann reversibel sein, so dass sich die durch die Benetzung gebildete Bindung der reduzierten Form des Speichermaterials 10 an bzw. auf der Oberfläche des benetzbaren Materials 11 bei einem Entladevorgang des EnergieSpeichers 1 lösen kann . Accordingly, FIG. 2 shows the state of charge or charged state of the energy store 1. The wetting of the wettable material 11 with the reduced shape of the storage material 10 is possible because the wetting angle between the reduced shape of the storage material 10 and the wettable material 11 is less than 90 °. In particular, the wetting angle between the reduced shape of the storage material 10 and the wettable material 11 is in the range of 5 to 75 °. The process of wetting the wettable material 11 with the storage material 10 in its reduced form may be reversible so that the bond formed by wetting the reduced form of the storage material 10 on the surface of the wettable material 11 in a discharge of the Energy storage 1 can solve.
Ersichtlich ist in der Matrix des Speicherelements 8 ferner ein partikel förmiges Abstandshaltematerial 12 vorgesehen . Das Abstandshaltematerial 12 liegt z . B . in Form von auf Yttrium- oxid bzw. Yttrium haltigen oxidischen Verbindungen basierenden Partikeln vor . Das Abstandshaltematerial 12 dient dazu, die Ausbildung von Partikel-Partikel-Kontakten des Speichermaterials 10 zu verhindern und somit eine bei den hohen, für den Betrieb des EnergieSpeichers 1 erforderlichen Temperatu- ren mögliche Versinterung bzw . Vergröberung des Speichermaterials 10 zu unterbinden . As can be seen in the matrix of the memory element 8 further comprises a particulate spacer material 12 is provided. The spacer material 12 is z. B. in the form of particles based on yttrium oxide or yttrium-containing oxidic compounds. The spacer material 12 serves to prevent the formation of particle-particle contacts of the memory material 10 and thus a possible sintering at the high temperatures required for the operation of the energy store 1. Coarsening of the memory material 10 to prevent.
Eine Benetzung des Abstandshaltematerial 12 mit dem Speichermaterial 10 ist weder in dessen reduzierter noch oxidierter Form gegenüber der Benetzung des benetzbaren Materials 11 durch das Speichermate ial 10 begünstigt . Der Benet zungswinkel zwischen dem Abstandshaltemate ial 12 und dem Speichermaterial 10 ist größer 90°. Mithin unterscheidet sich das benetzbare Material 11 von dem Abstandshaltematerial 12 wesent- lieh im Hinblick auf deren Benet zungswinkel gegenüber dem Speichermaterial 10 bzw . dessen reduzierter Form . Sowohl das benetzbare Material 11 als auch das Äbstandshalte- material 12 kann neben der beschriebenen Möglichkeit, dass es selbst partikelförmig bzw. granulär vorliegt , auch als Be- schichtung auf einem partikelförmigen, porösen Trägermaterial aufgebracht sein. Das Trägermaterial kann z. B. aus einem oxidkeramischen Material basierend auf Kalziumoxid, Magnesiumoxid, Zirkoniumoxid, Aluminiumoxid, Lanthanoxid, Nioboxid oder Tantaloxid oder Mischungen der Genannten gebildet sein . Der Anteil an Speichermaterial 10 in der Matrix des Speicherelements 8 liegt z. B. im Bereich von 30 bis 90 Vo1. -% , insbesondere oberhalb 40 Vo1. -% , bevorzugt obe halb 50 Vol . -% . Der Gesamtanteil an benetzbarem Material 11 und Abstandshal- tematerial 12 liegt in Summe im Bereich von 2 bis 40 Vo1. -% , insbesondere im Bereich von 5 bis 15 Vo1. -% , liegen . Wetting of the spacer material 12 with the storage material 10 is neither in its reduced nor oxidized form against the wetting of the wettable material 11 by the storage ial 10 favors. The wetting angle between the spacer material 12 and the memory material 10 is greater than 90 °. Thus, the wettable material 11 differs from the spacer material 12 substantially in terms of their Benet tion angle relative to the memory material 10 and. its reduced form. Both the wettable material 11 and the Äbstandshalte- material 12 may be applied in addition to the described possibility that it is itself particulate or granular, as a coating on a particulate, porous carrier material. The carrier material may, for. Example, be formed from an oxide ceramic material based on calcium oxide, magnesium oxide, zirconium oxide, aluminum oxide, lanthanum oxide, niobium oxide or tantalum oxide or mixtures of the above. The proportion of memory material 10 in the matrix of the memory element 8 is z. In the range of 30 to 90 Vo1. -%, especially above 40 Vo1. -%, preferably above 50 vol. -%. The total amount of wettable material 11 and spacer material 12 is in the range of 2 to 40 Vo1 in total. -%, in particular in the range of 5 to 15 Vo1. -% , lie .
Neben dem Speiche material 10, dem benetzbaren Material 11 und dem Abstandshaltematerial 12 ist ferner ein Volumenanteil an offene Porosität im Speicherelernent 8 vorhanden, der im Bereich von 10 bis 50 Vo1. -% , bevorzugt im Bereich von 25 bis 40 Vol . -%, liegt. In addition to the spoke material 10, the wettable material 11 and the spacer material 12, a volume fraction of open porosity in Speicherelernent 8 is also present in the range of 10 to 50 Vo1. -%, preferably in the range of 25 to 40 vol. -%, lies.
Selbstverständlich sind die Anteile der in der Matrix des Speiche elernents 8 enthaltenen Komponenten derart abgestimmt, dass sich in Summe ein Anteil von 100 Vo1. -% einstellt . Of course, the proportions of the components contained in the matrix of the spoke elernents 8 are tuned such that a total of 100 Vo1. -% setting.
Obwohl die Erfindung im Detail durch das bevorzugte Ausfüh- rungsbeispiel näher illustriert und beschrieben wurde, so ist die Erfindung nicht durch die offenbarten Beispiele einge- schränkt und andere Variationen können vom Fachmann hieraus abgeleitet werden, ohne den Schutzumfang der Erfindung zu verlassen . Although the invention has been further illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

Patentansprüche claims
1. Wiederaufladbarer elektrischer Energiespeicher (1), insbesondere Metalloxid-Luft-Energiespeicher, mit wenigstens einem Speicherelement (8) zur Speicherung elektrischer Energie, wobei das Speicherelement (8) ein im Ladebetrieb des Energiespeichers (1) reduzierbares und im Entladebetrieb des Energiespeichers (1) oxidierbares Speichermaterial (10) umfasst, dadurch gekennzeichnet, dass das Speicherelement (8) ein durch die reduzierte Form des Speichermaterials (10) zumindest abschnittsweise benetzbares Material (11) umfasst. 1. Rechargeable electrical energy storage device (1), in particular metal oxide air energy storage device, with at least one storage element (8) for storing electrical energy, wherein the storage element (8) in the charging operation of the energy store (1) reducible and in the discharge operation of the energy store (1 ) comprises oxidizable memory material (10), characterized in that the memory element (8) by the reduced form of the memory material (10) at least partially wettable material (11).
2. Wiederaufladbarer elektrischer Energiespeicher nach Anspruch 1, dadurch gekennzeichnet, dass der Benetzungswinkel der reduzierten Form des Speichermaterials (10) auf der Oberfläche des benetzbaren Materials (11) im Bereich von 1 bis 90°, insbesondere 1 bis 75°, liegt. 2. Rechargeable electrical energy storage device according to claim 1, characterized in that the wetting angle of the reduced form of the storage material (10) on the surface of the wettable material (11) in the range of 1 to 90 °, in particular 1 to 75 °.
3. Wiederaufladbarer elektrischer Energiespeicher nach An- spruch 1 ode 2, dadurch gekennzeichnet, dass das benetzbare3. Rechargeable electrical energy store according to claim 1 or 2, characterized in that the wettable
Material (11) aus einem oxidkeramischen Material basierend auf Ceroxid, Chromoxid, Gadoliniumoxid, Kupferoxid, Manganoxid, Titanoxid oder einer PerowskitVerbindung, bevorzugt der allgemeinen Form (RE, AE) (Fe, Ti, Cr, Mn, Co, Ni) 03, insbe- sondere aus den Kompositionsfeidern (Sr, Y) T1O3 oder (La, Ca, Sr, Ce) (Fe, Ti, Cr) O3 , oder Mischungen der Genannten gebildet ist . Material (11) of an oxide-ceramic material based on cerium oxide, chromium oxide, gadolinium oxide, copper oxide, manganese oxide, titanium oxide or a perovskite compound, preferably of the general form (RE, AE) (Fe, Ti, Cr, Mn, Co, Ni) O 3 , in particular from the Kompositionsfeidern (Sr, Y) T1O 3 or (La, Ca, Sr, Ce) (Fe, Ti, Cr) O3, or mixtures thereof is formed.
4. Wiederaufladbarer elektrischer Energiespeieher nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das benetzbare Material (11) partikel förmig ist . 4. Rechargeable electric energy according to one of the preceding claims, characterized in that the wettable material (11) is particulate.
5. Wiederaufladbarer elektrischer Energiespeieher nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das benetzbare Material (11) als Beschichtung auf einem partikel- förmigen Trägermaterial aufgebracht ist . 5. Rechargeable electrical energy according to one of the preceding claims, characterized in that the wettable material (11) is applied as a coating on a particulate carrier material.
6. Wiederaufladbarer elektrischer Energiespeieher nach Anspruch 5, dadurch gekennzeichnet, dass das Trägermaterial aus einem oxidkeramischen Material basierend auf Aluminiumoxid, Kalziumoxid, Lanthanoxid, Magnesiumoxid, Nioboxid, Tantal- oxid, Yttriumoxid, Zirkoniumoxid oder Mischungen der Genannten gebildet ist . 6. Rechargeable electrical energy according to claim 5, characterized in that the carrier material is formed from an oxide-ceramic material based on alumina, calcium oxide, lanthanum oxide, magnesium oxide, niobium oxide, tantalum oxide, yttrium oxide, zirconium oxide or mixtures of the above.
7. Wiederaufladbarer elektrischer Energiespeieher nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Speicherelement (8) ein Abstandshaltematerial ( 12 ) umfasst , wobei der Benet zungswinkel zwischen dem Abstandshaltematerial { 12 ) und der reduzierten Form des Speichermaterials (10) großer als 90° ist . 7. A rechargeable electrical energy according to one of the preceding claims, characterized in that the storage element (8) comprises a spacer material (12), wherein the Benet angle between the spacer material {12) and the reduced form of the storage material (10) greater than 90 ° is.
8. Wiederaufladbarer elektrischer Energiespeieher nach Anspruch 7, dadurch gekennzeichnet , dass das Abstandshaltematerial ( 12 ) aus einem oxidkeramischen Material basierend auf Zirkoniumoxid, Yttriumoxid und/oder Yttriumverbindungen gebildet ist . A rechargeable electric energy collector according to claim 7, characterized in that said spacer material (12) is formed of an oxide ceramic material based on zirconia, yttria and / or yttrium compounds.
9. Wiederaufladbarer elektrischer Energiespeieher nach Anspruch 7 oder 8, dadurch gekennzeichnet , dass das Abstandshaltematerial ( 12 ) partikel förmig ist . 9. Rechargeable electrical energy according to claim 7 or 8, characterized in that the spacer material (12) is particulate.
10. Wiederaufladbarer elektrischer Energiespeieher nach einem der Ansprüche 7 bis 9, dadurch gekennzeichnet , dass das Abstandshaltematerial ( 12 ) als Beschichtung auf einem partikel- förmigen Trägermaterial aufgebracht ist . 10. Rechargeable electric energy according to one of claims 7 to 9, characterized in that the spacer material (12) is applied as a coating on a particulate carrier material.
11. Wiederaufladbarer elektrischer Energiespeieher nach Anspruch 10, dadurch gekennzeichnet , dass das Trägermaterial aus einem oxidkeramischen Material basierend auf Kalziumoxid, Magnesiumoxid, Zirkoniumoxid, Aluminiumoxid, Lanthanoxid, Nioboxid oder Tantaloxid oder Mischungen der Genannten gebildet 11. A rechargeable electrical energy collector according to claim 10, characterized in that the carrier material of an oxide ceramic material based on calcium oxide, magnesium oxide, zirconium oxide, alumina, lanthanum oxide, niobium oxide or tantalum oxide or mixtures thereof
PCT/EP2014/050020 2013-01-16 2014-01-02 Rechargeable electric energy accumulator WO2014111273A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003001617A2 (en) * 2001-06-25 2003-01-03 Celltech Power, Inc. Electrode layer arrangements in an electrochemical device
EP1513214A1 (en) * 2003-09-05 2005-03-09 Sulzer Hexis AG High temperature fuel cell with stabilized cermet structure
US20120034520A1 (en) * 2010-08-09 2012-02-09 Chun Lu Self-sealed metal electrode for rechargeable oxide-ion battery cells
US20120058396A1 (en) * 2010-09-07 2012-03-08 Chun Lu Oxidation-resistant metal supported rechargeable oxide-ion battery cells and methods to produce the same
WO2012038312A1 (en) * 2010-09-20 2012-03-29 Siemens Aktiengesellschaft Rechargeable energy storage unit
DE102011017594A1 (en) * 2011-04-27 2012-10-31 Siemens Aktiengesellschaft Method for producing a porous body and cell of a rechargeable oxide battery

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3717085B2 (en) * 1994-10-21 2005-11-16 キヤノン株式会社 Negative electrode for secondary battery, secondary battery having the negative electrode, and method for producing electrode
DE102011004183A1 (en) * 2011-02-16 2012-08-16 Siemens Aktiengesellschaft Rechargeable energy storage unit

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003001617A2 (en) * 2001-06-25 2003-01-03 Celltech Power, Inc. Electrode layer arrangements in an electrochemical device
EP1513214A1 (en) * 2003-09-05 2005-03-09 Sulzer Hexis AG High temperature fuel cell with stabilized cermet structure
US20120034520A1 (en) * 2010-08-09 2012-02-09 Chun Lu Self-sealed metal electrode for rechargeable oxide-ion battery cells
US20120058396A1 (en) * 2010-09-07 2012-03-08 Chun Lu Oxidation-resistant metal supported rechargeable oxide-ion battery cells and methods to produce the same
WO2012038312A1 (en) * 2010-09-20 2012-03-29 Siemens Aktiengesellschaft Rechargeable energy storage unit
DE102011017594A1 (en) * 2011-04-27 2012-10-31 Siemens Aktiengesellschaft Method for producing a porous body and cell of a rechargeable oxide battery

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