Solid State Electrolytes

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Es wird erwartet, dass Feststoff-Lithium-Ionen-Batterien, die aus Feststoffelektroden und einem Lithium-Ionen leitenden Feststoffelektrolyten bestehen, die Sicherheitsprobleme (wie z.B. Dendriten Wachstum, Undichtigkeiten und Entflammbarkeit) der häufig genutzten Flüssigelektrolyt enthaltenden Lithium-Ionen-Batterien zu beseitigen. Zusätzlich zu der Verbesserung der Sicherheit bieten Feststoffelektrolyte ein weites elektrochemisches Stabilitätsfenster und eine hohe Temperaturstabilität. Es gibt bereits verschiedene Feststoffelektrolyt-Materialien mit gleicher oder höherer Lithium-Ionen Leitfähigkeit als bei flüssigen Elektrolyten, die allerdings über einem weiten Potentialbereich nicht stabil sind. Die größte Herausforderung ist, Material zu entwickeln, das alle erwähnten Eigenschaften vereint.

Der aktuelle Schwerpunkt unserer Forschungsgruppe liegt auf der Synthese von Feststoffelektrolyt-Nanopulver (kristallin und amorph) und deren Weiterverarbeitung in einen nanokörnigen Keramikfestkörper und auf der Untersuchung ihrer elektrochemischen Leistung. Zum Einsatz kommen zwei Hauptsynthesetechniken: chemische Gas-Phasensynthese (CVS) und Spraypyrolyse (NSP). Beide Verfahren bieten die Möglichkeit, nanokristallines Pulver zu synthetisieren, das die Untersuchung des Potenzials von nanokörnige Keramiken in Lithium-Ionen-Batterien erlaubt.

Verwendet man das Wissen von Festkörperkeramiken wird der Forschungsbereich der Herstellung von Feststoffelektrolyten als Dünnschichten erweitert, indem die beiden Methoden der modifizierten CVS und NSP genutzt werden: lasergestützte CVD (chemical vapor deposition, chemische Gasphasenabscheidung) (LACVD) und Spray CVD (NCVD). Diese Forschung wird darüber hinaus durch die integrierte UHV-Synthese und -Charakterisierungssystem (DAISY-BAT: DArmstadt Integrated SYstem for BATtery Research) unterstützt. Mithilfe dieses Systems können Dünnschichten von Elektrodenmaterialien und Feststoffelektrolyte entwickelt werden sowie die Oberflächen zu jedem Zeitpunkt des Wachstums mit analytischen Oberflächentechniken detailliert untersucht werden.

Miriam BotrosPhD StudentTel: +49 (06151) 16 20969Mail: m.botros(at)nano.tu-darmstadt.de
ForschungsgruppeSolid State Electrolytes
Prof. Dr.-Ing. Horst HahnPrincipal InvestigatorTel: +49 (0731) 50 34003Mail: horst.hahn(at)kit.edu
ForschungsgruppeSolid State Electrolytes
ForschungsgruppeSolid State Electrolytes

(images will be uploaded shortly)

Nanostructured battery materials

The group is operating a range of equipment for the synthesis of nanostructured electrode materials and solid electrolytes in the form of nanopowders and thin / thick films. The general scope is to analyse the potential of nanostructured materials for the improvement of safety, performance (energy and power density) and lifetime of cells. The current focus is on the characterization of solid electrolytes and of the interfaces between electrode materials and solid electrolytes for lithium ion batteries.

 

Solid Electrolytes

Typically, the solid electrolyte materials are synthesized  either by conventional solid-state reactions or solution-based techniques. In our research group gas-phase and aerosol techniques are used: Chemical Vapor Synthesis (CVS) and Nebulized Spray Pyrolysis (NSP). Both techniques offer the possibility to synthesize nanocrystalline powders and thus allow the study of the potential of nanostructured electrolytes in lithium ion batteries. Modifications of these two techniques allow the deposition of thin-films via so-called Laser-Assisted Chemical Vapor Depositon (LACVD) and Nebulized Chemical Vapor Deposition (NCVD).

 

Chemical Vapor Synthesis (CVS)

Using CVS, nanoparticles are prepared by the chemical reaction of precursors in the gas phase. The technique is essentially a modification of Chemical Vapor Deposition (CVD) for the preparation of thin films. The variation of the process parameters (temperature, supersaturation, residence time) compared to CVD results in the homogeneous nucleation of nanoparticles in the gas phase instead of heterogeneous film formation. Advantages of gas phase reactions are short residence times and controlled atmosphere resulting in nanoscaled powders of high purity, crystallinity, narrow particle size distribution and low degree of agglomeration.

 

Nebulized Spray Pyrolysis (NSP)

NSP is an aerosol technique where thermolysis of precursors and annealing of the particles occur simultaneously resulting in the formation of nanocrystalline powders without organic residues. As a consequence, long-time post-annealing and milling is not required, resulting in a reduction of the processing time compared to other techniques (solid-state reactions, solution-based).

 

 

Laser-Assisted Chemical Vapor Depositon (LACVD)

LACVD is a newly established method for thin-film deposition by CO2-laser evaporation of solid precursors with low volatility, which evaporate instantaneously by absorption of infrared laser radiation. The method is applicable whenever functional multicomponent films and coatings with a complex stoichiometry and composition are needed. By tuning the process parameters, films with different morphologies and thicknesses can be obtained. This method has a potential for in-situ all-solid-state battery deposition. Furthermore, the LACVD is integrated in a system (DAISY-BAT) which allows the structural characterization of the films using a range of surface sensitive techniques.

 

 

Nebulized Chemical Vapor Deposition (NCVD)

NCVD is a modified NSP method where the precursor droplets are deposited on a heated substrate. As a result, dense or porous films can obtained depending on the deposition parameters. This method can be used for deposition of a wide range of materials with stoichiometry composition.

 

 

Garnet-based Solid Electrolyte

Nebulized spray pyrolysis followed by consolidation and sintering was used for the first time to prepare Al-doped garnet-based Li7-3xLa3Zr2AlxO12 (x = 0 – 0.25) (LLZO) ultra-fine grained ceramics. The structural changes from the tetragonal (x = 0), via a mixture of the cubic and the tetragonal (x = 0.07, 0.10) to the cubic modification (x = 0.15 – 0.25) were observed. Despite their low relative density (47 – 56 %), preliminary ionic conductivities of the LLZO ceramics, were found to be 1.2·10-6 S cm-1 and 4.4·10-6 S cm-1 for tetragonal and cubic LLZO at room temperature, with activation energies of 0.55 eV and 0.49 eV, respectively.

 

Ongoing research is focused on the optimization of the sintering conditions by employing different sintering techniques (hot-pressing, spark plasma sintering) in order to obtain ceramics with substantially higher density to improve the Li-ion conductivity.

(images will be uploaded shortly)

Laboratories:

  • Nanopowder preparation by chemical vapor synthesis (CVS) and nebulized spray pyrolysis (NSP)
  • Thin-film preparation by laser assisted chemical vapor deposition (LACVD) and nebulized chemical vapor deposition  (NCVD)
  • Powder characterization (X-ray diffraction, Nitrogen adsorption, Dynamic light scattering)
  • Battery assembling and characterization (Impedance, Cyclic voltammetry)

Instruments and Hardware:

  • Powder X-ray diffractometer (Cu) with automatic sample changer and high-temperature chamber (Bruker D8)
  • Surface area and pore size distribution analyser (low-temperature nitrogen adsorption – Quantachrome Autosorb-3B)
  • Particle size and Zeta potential analyser (Dynamic light scattering –Zetasizer Nano-ZS Malvern)
  • High Frequency Response Analyser (Solartron 1260) with Potentiostat/Galvanostat (Solartron 1287) and Cryostat (77 K – 600 K, Janis)
  • 8-Chenell Solatron 1400 CellTest System with constant climate chamber (0 °C – 70 °C, Memmert)
  • 3 MBRAUN Ar-gloveboxes with drying ovens and freezers (precursor preparation, CVS powder collection, battery assembling)
  • Several high-temperature tube furnaces (one and three zone, up to 1600°C)
  • Chamber furnaces (up to 1700 °C, Carbolite, Nabertherm)
  • Drying ovens (air and argon atmosphere)
  • Ball mills (RETSCH high energy – PM100 & cryomill)
  • High-temperature (up to 600°C) uniaxial press
  • Spin coater (Laurell WS-400B-6NPP/Lite)
  • Ultrasonic bath
  • Ultrasonic horn (Hielscher UP400S & UP200S)
  • Centrifuge (Hettich EBA-21, 18 000 rpm)
  • High precision balances

(information will be uploaded shortly)

A specific filter for this group’s publications is not yet available. Please take a look at „publications“ in the website’s header for now.

Mitglieder
Miriam BotrosPhD StudentTel: +49 (06151) 16 20969Mail: m.botros(at)nano.tu-darmstadt.de
ForschungsgruppeSolid State Electrolytes
Prof. Dr.-Ing. Horst HahnPrincipal InvestigatorTel: +49 (0731) 50 34003Mail: horst.hahn(at)kit.edu
ForschungsgruppeSolid State Electrolytes
ForschungsgruppeSolid State Electrolytes
Forschung

(images will be uploaded shortly)

Nanostructured battery materials

The group is operating a range of equipment for the synthesis of nanostructured electrode materials and solid electrolytes in the form of nanopowders and thin / thick films. The general scope is to analyse the potential of nanostructured materials for the improvement of safety, performance (energy and power density) and lifetime of cells. The current focus is on the characterization of solid electrolytes and of the interfaces between electrode materials and solid electrolytes for lithium ion batteries.

 

Solid Electrolytes

Typically, the solid electrolyte materials are synthesized  either by conventional solid-state reactions or solution-based techniques. In our research group gas-phase and aerosol techniques are used: Chemical Vapor Synthesis (CVS) and Nebulized Spray Pyrolysis (NSP). Both techniques offer the possibility to synthesize nanocrystalline powders and thus allow the study of the potential of nanostructured electrolytes in lithium ion batteries. Modifications of these two techniques allow the deposition of thin-films via so-called Laser-Assisted Chemical Vapor Depositon (LACVD) and Nebulized Chemical Vapor Deposition (NCVD).

 

Chemical Vapor Synthesis (CVS)

Using CVS, nanoparticles are prepared by the chemical reaction of precursors in the gas phase. The technique is essentially a modification of Chemical Vapor Deposition (CVD) for the preparation of thin films. The variation of the process parameters (temperature, supersaturation, residence time) compared to CVD results in the homogeneous nucleation of nanoparticles in the gas phase instead of heterogeneous film formation. Advantages of gas phase reactions are short residence times and controlled atmosphere resulting in nanoscaled powders of high purity, crystallinity, narrow particle size distribution and low degree of agglomeration.

 

Nebulized Spray Pyrolysis (NSP)

NSP is an aerosol technique where thermolysis of precursors and annealing of the particles occur simultaneously resulting in the formation of nanocrystalline powders without organic residues. As a consequence, long-time post-annealing and milling is not required, resulting in a reduction of the processing time compared to other techniques (solid-state reactions, solution-based).

 

 

Laser-Assisted Chemical Vapor Depositon (LACVD)

LACVD is a newly established method for thin-film deposition by CO2-laser evaporation of solid precursors with low volatility, which evaporate instantaneously by absorption of infrared laser radiation. The method is applicable whenever functional multicomponent films and coatings with a complex stoichiometry and composition are needed. By tuning the process parameters, films with different morphologies and thicknesses can be obtained. This method has a potential for in-situ all-solid-state battery deposition. Furthermore, the LACVD is integrated in a system (DAISY-BAT) which allows the structural characterization of the films using a range of surface sensitive techniques.

 

 

Nebulized Chemical Vapor Deposition (NCVD)

NCVD is a modified NSP method where the precursor droplets are deposited on a heated substrate. As a result, dense or porous films can obtained depending on the deposition parameters. This method can be used for deposition of a wide range of materials with stoichiometry composition.

 

 

Garnet-based Solid Electrolyte

Nebulized spray pyrolysis followed by consolidation and sintering was used for the first time to prepare Al-doped garnet-based Li7-3xLa3Zr2AlxO12 (x = 0 – 0.25) (LLZO) ultra-fine grained ceramics. The structural changes from the tetragonal (x = 0), via a mixture of the cubic and the tetragonal (x = 0.07, 0.10) to the cubic modification (x = 0.15 – 0.25) were observed. Despite their low relative density (47 – 56 %), preliminary ionic conductivities of the LLZO ceramics, were found to be 1.2·10-6 S cm-1 and 4.4·10-6 S cm-1 for tetragonal and cubic LLZO at room temperature, with activation energies of 0.55 eV and 0.49 eV, respectively.

 

Ongoing research is focused on the optimization of the sintering conditions by employing different sintering techniques (hot-pressing, spark plasma sintering) in order to obtain ceramics with substantially higher density to improve the Li-ion conductivity.

Equipment

(images will be uploaded shortly)

Laboratories:

  • Nanopowder preparation by chemical vapor synthesis (CVS) and nebulized spray pyrolysis (NSP)
  • Thin-film preparation by laser assisted chemical vapor deposition (LACVD) and nebulized chemical vapor deposition  (NCVD)
  • Powder characterization (X-ray diffraction, Nitrogen adsorption, Dynamic light scattering)
  • Battery assembling and characterization (Impedance, Cyclic voltammetry)

Instruments and Hardware:

  • Powder X-ray diffractometer (Cu) with automatic sample changer and high-temperature chamber (Bruker D8)
  • Surface area and pore size distribution analyser (low-temperature nitrogen adsorption – Quantachrome Autosorb-3B)
  • Particle size and Zeta potential analyser (Dynamic light scattering –Zetasizer Nano-ZS Malvern)
  • High Frequency Response Analyser (Solartron 1260) with Potentiostat/Galvanostat (Solartron 1287) and Cryostat (77 K – 600 K, Janis)
  • 8-Chenell Solatron 1400 CellTest System with constant climate chamber (0 °C – 70 °C, Memmert)
  • 3 MBRAUN Ar-gloveboxes with drying ovens and freezers (precursor preparation, CVS powder collection, battery assembling)
  • Several high-temperature tube furnaces (one and three zone, up to 1600°C)
  • Chamber furnaces (up to 1700 °C, Carbolite, Nabertherm)
  • Drying ovens (air and argon atmosphere)
  • Ball mills (RETSCH high energy – PM100 & cryomill)
  • High-temperature (up to 600°C) uniaxial press
  • Spin coater (Laurell WS-400B-6NPP/Lite)
  • Ultrasonic bath
  • Ultrasonic horn (Hielscher UP400S & UP200S)
  • Centrifuge (Hettich EBA-21, 18 000 rpm)
  • High precision balances
Zusammenarbeit

(information will be uploaded shortly)

Publikationen

A specific filter for this group’s publications is not yet available. Please take a look at „publications“ in the website’s header for now.

Fakten zur Gruppe

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