DE3305405C1 - Method of increasing the electrochemical activity of Ti2Ni particles - Google Patents

Method of increasing the electrochemical activity of Ti2Ni particles

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Publication number
DE3305405C1
DE3305405C1 DE3305405A DE3305405A DE3305405C1 DE 3305405 C1 DE3305405 C1 DE 3305405C1 DE 3305405 A DE3305405 A DE 3305405A DE 3305405 A DE3305405 A DE 3305405A DE 3305405 C1 DE3305405 C1 DE 3305405C1
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ti2ni
tini
layer
particles
particle
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German (de)
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Eberhard Dr. 7300 Esslingen Schmidt-Ihn
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Daimler Benz AG
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Daimler Benz AG
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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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/383—Hydrogen absorbing alloys
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/0005—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes
    • C01B3/001—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes characterised by the uptaking medium; Treatment thereof
    • C01B3/0031—Intermetallic compounds; Metal alloys; Treatment thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/0005—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes
    • C01B3/001—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes characterised by the uptaking medium; Treatment thereof
    • C01B3/0078—Composite solid storage mediums, i.e. coherent or loose mixtures of different solid constituents, chemically or structurally heterogeneous solid masses, coated solids or solids having a chemically modified surface region
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/0005—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes
    • C01B3/001—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes characterised by the uptaking medium; Treatment thereof
    • C01B3/0084—Solid storage mediums characterised by their shape, e.g. pellets, sintered shaped bodies, sheets, porous compacts, spongy metals, hollow particles, solids with cavities, layered solids
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/06—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of metallic material
    • 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
    • Y02E60/32—Hydrogen storage

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Inorganic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Electrochemistry (AREA)
  • Powder Metallurgy (AREA)

Abstract

A method is described for increasing the electrochemical activity of Ti2Ni particles for hydrogen storage electrodes, based on a layer of TiNi being produced on at least a part of the surface of the Ti2Ni particles. The TiNi layer can in this connection have a thickness of up to 15% of the radius of the Ti2Ni particle. A coating of at least 50%, and in particular 100%, of the surface of the Ti2Ni particle by the TiNi layer is preferred. The TiNi layer is preferably produced by reducing the Ti content in the surface of the Ti2Ni particle by allowing the Ti2Ni particles to react with a desired amount of iodine, the resultant TiI4 being removed from the reaction mixture by, for instance, the application of a vacuum, and the particles being then sintered.

Description

Die elektrochemische Kapazität der so hergestellten Ti2Ni-Partikel beträgt etwa 360 Ah/kg und liegt damit um mehr als 1296 über der Ladungsdichte der besten bisher bekannten TiNi-Legierungen. The electrochemical capacity of the Ti2Ni particles produced in this way is around 360 Ah / kg and is therefore more than 1296 higher than the charge density of the best known TiNi alloys.

Beispiel Durch Zusammenschmelzen von 62,0 g Ti und 38,0 g Ni wurden 100g Tl2Ni hergestellt. Das so hergestellte TkNi wurde fein gemahlen und aus dem Produkt der Mahlung wurde eine Fraktion mit einer Korngröße von weniger als 30 gm durch Siebung abgetrennt. 10 g dieser Fraktion wurden mit 2,5 g Jod vermischt, und die Mischung wurde in ein Stahlgefäß gefüllt, welches mit einer zu einer Vakuumpumpe führenden Vakuumleitung verbunden war. Das Gefäß wurde verschlossen, evakuiert, dle Vakuumleitung wurde geschlossen und das Getliß wurde etwa 3 Std. auf 500° C erhitzt, um das Ti2Ni mit dem Jod reagieren zu lassen. Anschließend wurde die Vakuumleitung wieder geöffnet und das gebildete TiJ4 sowie etwa noch nicht umgesetztes Jod wurde bei der Reaktionstemperatur von 5000 C innerhalb einer halben Stunde bei elnem Vakuum von <10-2m bar aus dem Reaktionsgefäß abgezogen. Das entstandene Material wurde dann bei 8500 C unter Wasserstoff 48 Stunden gesintert, um die TiNi-Schicht zu erzeugen. Eine Analyse ergab, daß das Ti2Ni-Pulver nach der Sinterung einen Gehalt von etwa 5 Gew.-96 TiNi aufwies, was bei einer gleichmäßigen Verteilung über die Oberfläche der TizNi-Körner bei einem Korndurchmesser von 30 #m einer 0,5 #m dicken Schicht auf jedem Ti2Nl-Korn entspricht. Example By melting together 62.0 g of Ti and 38.0 g of Ni, 100g Tl2Ni produced. The TkNi produced in this way was finely ground and made from the The product of the grinding was a fraction with a grain size of less than 30 μm separated by sieving. 10 g of this fraction were mixed with 2.5 g of iodine, and the mixture was poured into a steel vessel connected to a vacuum pump leading vacuum line was connected. The jar was sealed, evacuated, The vacuum line was closed and the jar was heated to 500 ° C. for about 3 hours heated to let the Ti2Ni react with the iodine. Then the vacuum line reopened and the TiJ4 formed and any iodine that had not yet reacted was at the reaction temperature of 5000 C within half an hour under elnem vacuum of <10-2m bar withdrawn from the reaction vessel. The resulting material was then sintered at 8500 C under hydrogen for 48 hours to produce the TiNi layer. An analysis showed that the Ti2Ni powder after sintering a content of about 5% by weight of TiNi, which was evenly distributed over the surface of the TizNi grains with a grain diameter of 30 μm in a 0.5 μm thick layer on each Ti2Nl grain.

Das gesinterte Pulver wurde anschließend in an sich bekannter Weise mit Kupferpulver vermischt und zu einer Elektrode mit innenliegendem Kupfernetz verpreßt. The sintered powder was then made in a manner known per se mixed with copper powder and formed into an electrode with an internal copper mesh pressed.

Diese Elektrode wurde in an sich bekannter Weise elektrochemisch durch mehrmaliges Sstündiges Be- und Entladen aktiviert und dann die Ladungsdichte bis zu -700mV gegen Hg/HgO vermessen. Die Ladungsdichte dieser Elektrode betrug in der 10-h-Entladung 360 Ah/kg Tl2Nl. In der Abbildung ist die erfindungsgemäß erzielbare elektrochemlsche Kapazität der theoretischen Kapazltät und der gemäß dem Stand der Technik erreichbaren elektrochemischen Kapazität gegenübergestellt. Der gemäß der Erfindung erreichbare Fortschritt wird dadurch besonders deutlich.This electrode was electrochemically carried out in a manner known per se several hours of loading and unloading activated and then the charge density up to measured at -700mV against Hg / HgO. The charge density of this electrode was in 10-hour discharge 360 Ah / kg Tl2Nl. The figure that can be achieved according to the invention is shown in the figure electrochemical capacity of the theoretical capacity and according to the state of the Technology compared to achievable electrochemical capacity. According to the Invention achievable progress becomes particularly clear.

Claims (5)

Patentansprüche: 1. Verfahren zur Erhöhung der elektrochemischen Aktivität von Ti2-Ni-Partikeln für Wasserstoffspei cherelektroden, dadurch gekennzeichnet, daß man zumindest auf einem Teil der Oberfläche der Partikel eine Schicht aus TiNi erzeugt. Claims: 1. Method for increasing the electrochemical Activity of Ti2-Ni particles for hydrogen storage electrodes, characterized in that that at least on part of the surface of the particles a layer of TiNi generated. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die TiNi-Schicht bis zu 15% des Ti2Ni-Partikelradius dick ist. 2. The method according to claim 1, characterized in that the TiNi layer is up to 15% of the Ti2Ni particle radius thick. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß mindestens 50%, insbesondere 100X der Oberfläche durch die TiNi-Schicht bedeckt ist. 3. The method according to claim 1 or 2, characterized in that at least 50%, in particular 100X, of the surface is covered by the TiNi layer is. 4. Verfahren nach den Ansprüchen 1 bis 3, dadurch gekennzeichnet, daß man die TiNi-Schicht durch Verringerung des Ti-Gehalts in der Oberfläche der Ti2Ni-Partikel erzeugt. 4. The method according to claims 1 to 3, characterized in that that the TiNi layer by reducing the Ti content in the surface of the Ti2Ni particles generated. 5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß man die Ti2Ni-Partikel mit einer zur Umwandlung einer gewünschten Menge von Titanatomen in TiJ4 erforderlichen Menge Jod umsetzt, das gebildete TiJ4 von den Partikeln entfernt und die Partikel anschließend sintert. 5. The method according to claim 4, characterized in that the Ti2Ni particles with an amount capable of converting a desired amount of titanium atoms converts the required amount of iodine into TiJ4, the TiJ4 formed is removed from the particles and then sinter the particles. Es ist bekannt, TiNi und Tl2Ni sowohl in reiner Form als auch als Phasengemisch als aktive Masse in Wasserstoffspeicherelektroden zu benutzen (DE-OS 22 00 806, DE-PS 21 60 202, US-PS 38 24 131). Derartige Wasserstoffspeicherelektroden können in alkalischen Akkumulatoren verwendet werden. Sie sind elektrochemisch mit Wasserstoff be- und entladbar, wobei beim Beladen aus den Legierungen Hydride gebildet werden, die beim Entladen unter Wasserstoffabgabe wieder in die Ausgangslegierungen zerfallen. It is known to use TiNi and Tl2Ni both in pure form and as To use phase mixture as active mass in hydrogen storage electrodes (DE-OS 22 00 806, DE-PS 21 60 202, US-PS 38 24 131). Such hydrogen storage electrodes can be used in alkaline batteries. They are electrochemical with Hydrogen can be loaded and unloaded, with hydrides formed from the alloys during loading which are returned to the starting alloys when discharging, releasing hydrogen disintegrate. Gemäß der Formel TiNiH ergibt sich damit für die Legierung TiNi eine theoretische Ladungsdichte von 249 Ah/kg und für Tl2Ni gemäß der Formel Ti2NiH2,5 eine theoretische Ladungsdichte von 428 Ah/kg. According to the formula TiNiH, this results in a for the alloy TiNi theoretical charge density of 249 Ah / kg and for Tl2Ni according to the formula Ti2NiH2.5 a theoretical charge density of 428 Ah / kg. Es hat sich jedoch gezeigt, daß die hohe Ladungsdichte von 428 Ah/kg des Ti2NiH2,5 in der Praxis nicht erreichbar ist, da lediglich eine Ladungsmenge von 150 bis 170 Ah/kg nutzbar ist. D. h., bei der elektrochemi schen Entladung verbleibt Wasserstoff entsprechend einer Ladungsmenge von etwa 270 Ah/kg unbenUtzt zurück. However, it has been shown that the high charge density of 428 Ah / kg of the Ti2NiH2.5 cannot be achieved in practice, as there is only one amount of charge from 150 to 170 Ah / kg can be used. That is, remains at the electrochemical discharge Unused hydrogen corresponding to an amount of charge of approx. 270 Ah / kg. Nun ist es zwar aus US-PS 38 24 131 bekannt, daß eine aus etwa 63% Ti2Ni und 3796 TiNi bestehende Legierung (Phasenmischung) eine Kapazität von etwa 310 Ah/kg besitzt, was nahe an dem für eine solche Legierung möglichen theoretischen Wert von 314 Ah/kg liegt. Von der theoretisch möglichen Ladungsdichte des Ti2Ni von 428 Ah/kg ist jedoch diese Phasenmischung noch weit entfernt. Now it is known from US-PS 38 24 131 that one of about 63% Ti2Ni and 3796 TiNi existing alloy (phase mixture) have a capacity of about 310 Ah / kg, which is close to the theoretical possible for such an alloy Value of 314 Ah / kg. From the theoretically possible charge density of the Ti2Ni However, this phase mixture is still a long way from 428 Ah / kg. Die Aufgabe der Erfindung besteht daher darin, ein Verfahren zur Erhöhung der elektrochemischen Aktivität von Ti2Ni-Partikeln zu finden, das es ermöglicht, die hohe theoretische Speicherkapazität des Ti2Ni vqn 428 Ah/kg wesentlich besser als bisher zu nutzen. The object of the invention is therefore to provide a method for To find an increase in the electrochemical activity of Ti2Ni particles, which enables the high theoretical storage capacity of the Ti2Ni of 428 Ah / kg is much better to use than before. Diese Aufgabe wird durch das in den Patentansprüchen beschriebene Verfahren gelöst. This object is achieved by what is described in the claims Procedure solved. Es-konnte gefunden werden, daß die hohe Speicherka- pazität des Ti2Ni wesentlich besser ausgeschöpft werden kann, wenn die Ti2Ni-Partikel zumindest auf einem Teil ihrer Oberfläche mit einer Schicht von TiNi überzogen werden. Diese TiNi-Schicht, die eine Phasengrenze sowohl zum Elektrolyten als auch zum Ti2Ni besitzt, überträgt den aus dem reinen Ti2NiH25 elektrochemisch nicht mehr entladbaren Wasserstoff an den Elektrolyten (H-Transfer) und schöpft so die hohe Ladungsdichte des Ti2NiH25 besser aus. Da in dieser Reaktion nur TiNi-Partikel, die sowohl eine Phasengrenze zu Elektrolyten als auch zum Ti2Ni besitzen, aktiv sind, besitzen TiNl-Partikel, die im Inneren des Ti2Ni-Partikels liegen und von diesem vollständig umgeben sind, keine Wirkung. Die Phasengrenze TiNi/Elektrolyt kann dabei noch zusätzlich durch eine Metallschicht (z. B. Kupferschicht aus dem Leitfähigkeitsgerüst der Elektrode) unterbrochen sein. Es ist ferner nicht erforderlich, daß die gesamte Oberfläche des Ti2Ni-Partikels durch die TiNi-Schicht bedeckt ist, vielmehr reicht es aus, wenn die TiNi-Schicht nur einen Teil der Oberfläche, bevorzugt mindestens etwa 50%, bedeckt. Am günstigsten ist jedoch eine vollständige Bedeckung der Oberfläche durch TiNi. It was found that the high storage capacity capacity of the Ti2Ni Much better can be exploited if the Ti2Ni particles at least part of their surface can be coated with a layer of TiNi. This TiNi layer, which has a phase boundary both to the electrolyte and to the Ti2Ni, transfers the hydrogen, which can no longer be electrochemically discharged from the pure Ti2NiH25 the electrolyte (H-transfer) and thus draws the high charge density of the Ti2NiH25 better off. Because in this reaction only TiNi particles, which both form a phase boundary to electrolytes as well as to Ti2Ni, are active, have TiNl particles, which lie inside the Ti2Ni particle and are completely surrounded by it, no effect. The TiNi / electrolyte phase boundary can also pass through a metal layer (e.g. copper layer from the conductivity structure of the electrode) be interrupted. It is also not necessary that the entire surface of the Ti2Ni particle is covered by the TiNi layer, rather it is sufficient if the TiNi layer only part of the surface, preferably at least about 50%, covered. However, it is best to completely cover the surface TiNi. Die auf dem Ti2Ni-Partikel erzeugte TiNi-Schicht kann dabei außerordentlich dünn sein. Aus praktischen Erwägungen heraus wird man jedoch im allgemeinen Schichtdicken von bis zu etwa 15% des Ti2Ni-Partikelradius bevorzugen. Eine zu große Schichtdicke für das TiNi, z. B. mehr als 15% des Ti2Ni-Partikelradius, bringt keine weiteren Verbesserungen mit sich, führt jedoch zu einem verhältnismäßig hohen TlNi-Gehalt des Speichermaterlals, womit eine unerwünschte Minderung der Speicherkapazität verbunden ist. The TiNi layer produced on the Ti2Ni particle can be extraordinary be thin. For practical reasons, however, one will generally use layer thicknesses up to about 15% of the Ti2Ni particle radius. Too great a layer thickness for the TiNi, e.g. B. more than 15% of the Ti2Ni particle radius, brings no more Improvements with it, but leads to a relatively high TlNi content of the storage material, which is associated with an undesirable reduction in storage capacity is. Die Erzeugung der TiNi-Schicht auf den Ti2Ni-Partikel kann durch alle bekannten Verfahren, z. B. durch Vermahlen, erfolgen. Als besonders vorteilhaft hat sich jedoch herausgestellt, die TiNi-Schicht durch Verminderung des Ti-Gehaltes in der Oberfläche der Ti2Ni-Partlkel zu erzeugen, indem man aus der Oberfläche der Ti2Ni-Partikel selektiv Ti-Atome entfernt. The generation of the TiNi layer on the Ti2Ni particles can be achieved by all known methods, e.g. B. by grinding. As particularly beneficial however, it has been found that the TiNi layer is reduced by reducing the Ti content in the surface of the Ti2Ni particles by cutting from the surface of the Ti2Ni particles selectively removed Ti atoms. Besonders vorteilhaft ist diese Entfernung von Titan-Atomen aus der Oberfläche durch Reaktion der Titan-Atome mit Jod unter Bildung von TiJ4 gemäß der Reaktionsgleichung welches bei erhöhter Temperatur im Vakuum gasförmig aus der Reaktionszone entfernt werden kann. Entsprechend dem relativ hohen Dampfdruck des TiJ, reichen dabei Temperaturen im Bereich von 400 bis 500 C und ein Vakuum kleiner oder gleich 10-2 mbar aus. Die erforderliche Menge Jod läßt sich entweder experimentell oder rein rechnerisch unter Zugrundelegung der Teil chengröße der Ti2Ni-Partikel und der gewünschten Schichtdicke der TiNi-Schicht leicht ermitteln. Nach der Entfernung des TiJ4 wird durch einen Sinterprozeß im an sich bekannten Temperaturbereich von 800 bis 900 C mittels einer Festkörperreaktion aus der an Titan verarmten Oberflächenzone eine TiNi-Oberflächenschlcht erzeugt, welche das ansonsten unveränderte Ti2Ni umgibt: Das TiNi bildet sich dabei im allgemeinen als zusammenhängende, das Korn umhüllende Schicht aus.This removal of titanium atoms from the surface by reaction of the titanium atoms with iodine with formation of TiI4 according to the reaction equation is particularly advantageous which can be removed in gaseous form from the reaction zone at elevated temperature in vacuo. Corresponding to the relatively high vapor pressure of the TiJ, temperatures in the range from 400 to 500 C and a vacuum less than or equal to 10-2 mbar are sufficient. The required amount of iodine can be easily determined either experimentally or purely by calculation based on the particle size of the Ti2Ni particles and the desired layer thickness of the TiNi layer. After the TiJ4 has been removed, a sintering process in the known temperature range of 800 to 900 C by means of a solid-state reaction from the titanium-depleted surface zone creates a TiNi surface layer which surrounds the otherwise unchanged Ti2Ni: The TiNi is generally formed as a cohesive layer that envelops the grain.
DE3305405A 1983-02-17 1983-02-17 Method of increasing the electrochemical activity of Ti2Ni particles Expired DE3305405C1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3444998A1 (en) * 1984-08-10 1986-02-13 Sanyo Electric Co., Ltd., Moriguchi, Osaka METAL / HYDROGEN ALKALI ACCUMULATOR BATTERY
EP0273625A2 (en) * 1986-12-29 1988-07-06 Energy Conversion Devices, Inc. A method of making a sealed rechargeable hydrogen storage cell

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2051053A1 (en) * 1970-10-17 1972-04-20 Siemens Ag Dititanium nickelide negative plate - for accumulators and fuel cells with alloyed molybdenum to delay ageing
DE1771239B2 (en) * 1967-05-02 1973-12-20 Battelle Memorial Institute, Carouge, Genf (Schweiz) Accumulator electrode with storage capacity for hydrogen and process for their production
DE2200806B2 (en) * 1972-01-08 1976-07-29 Deutsche Automobilgesellschaft Mbh, 3000 Hannover METHOD OF MANUFACTURING A HYDROGEN STORAGE ELECTRODE
DE2160202B2 (en) * 1971-12-04 1978-07-13 Deutsche Automobilgesellschaft Mbh, 3000 Hannover Method for manufacturing a hydrogen storage electrode
DE2317505C2 (en) * 1972-04-06 1981-11-12 Battelle Memorial Institute, 1227 Carouge, Genf Negative electrode for alkaline galvanic power storage cells and process for their manufacture

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1771239B2 (en) * 1967-05-02 1973-12-20 Battelle Memorial Institute, Carouge, Genf (Schweiz) Accumulator electrode with storage capacity for hydrogen and process for their production
DE2051053A1 (en) * 1970-10-17 1972-04-20 Siemens Ag Dititanium nickelide negative plate - for accumulators and fuel cells with alloyed molybdenum to delay ageing
DE2160202B2 (en) * 1971-12-04 1978-07-13 Deutsche Automobilgesellschaft Mbh, 3000 Hannover Method for manufacturing a hydrogen storage electrode
DE2200806B2 (en) * 1972-01-08 1976-07-29 Deutsche Automobilgesellschaft Mbh, 3000 Hannover METHOD OF MANUFACTURING A HYDROGEN STORAGE ELECTRODE
DE2317505C2 (en) * 1972-04-06 1981-11-12 Battelle Memorial Institute, 1227 Carouge, Genf Negative electrode for alkaline galvanic power storage cells and process for their manufacture

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3444998A1 (en) * 1984-08-10 1986-02-13 Sanyo Electric Co., Ltd., Moriguchi, Osaka METAL / HYDROGEN ALKALI ACCUMULATOR BATTERY
EP0273625A2 (en) * 1986-12-29 1988-07-06 Energy Conversion Devices, Inc. A method of making a sealed rechargeable hydrogen storage cell
EP0273625A3 (en) * 1986-12-29 1989-06-14 Energy Conversion Devices, Inc. Activated rechargeable hydrogen storage electrode and method

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