Bez tytulu slajdu

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JRC-IE training workshop Petten, The
Netherlands 28-29th October 2004
The progress of nanocrystalline
hydride materials
M. Jurczyk Poznan University of
Technology Institute of Materials Science and
Engineering Poznan, Poland jurczyk_at_sol.put.poznan
.pl
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Introduction

• The presentation review the advantages of some
  nanomaterials, their application in
  electrochemistry and the challenges involved in
  their fabrication .
• Details of the processing used and the
  enhancement of properties due to the nanoscale
  structures will be presented.

M. Jurczyk, Bull. Pol. Ac. Tech. 52(1) (2004)
47-57.
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AIM of the STUDIES

• To produce nanoscale materials for energy storage
  by simple milling methods (mechanical alloying)
  from the pure elements
• To study the effect of the microstructue and
  addition of 3d metals on electrochemical
  behaviour of TiFe, ZrV2, LaNi5 and Mg2Ni - type
  alloys

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Mechanical Alloying by J.S. Benjamin in
Scientific American, May 1976, Vol. 234 (5) p.
40-57 Many useful combinations of metals cannot
be achieved by melting or by conventional powder
metallurgy. Such materials can be made by
cold-welding metal powders in a special
high-energy ball mill
Mechanical alloying ? What does it mean ?
Spex Mixer/Mill welding and fracturing
General behaviour of the powder particles A and B
during mechanical alloying process.
Today, it is possible to prepare metal/alloy
nanocrystals
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RESULTS
XRD spectra of nanocrystalline TiFe (a), ZrV2
(b), LaNi5 (c) and Mg2Ni (d) alloys produced by
mechanical alloying followed by annealing
(TiFe MA for 20 h and heat treated at 700oC for
0.5 h ZrV2 and LaNi5 MA 30 h and head treated at
700oC for 0.5 h Mg2Ni MA 90 h and head treated
at 450oC for 0.5 h)
M. Jurczyk, Current Topics in Electrochem.
9, 105-116 (2003)
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LaNi5-type
XRD spectra of a mixture of La and Ni powders
mechanically alloyed for different times in an
argon atmosphere a) initial state (elemental
powder mixture), b) after MA for 30 h and c) heat
treated at 700C for 0.5 h.
M. Jurczyk, Current Topics in Electrochem. 9,
105-116 (2003).
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TEM (A) and SEM (B) of a mixture of La and Ni
powders mechanically alloyed for 30 h under argon
atmosphere.
M. Jurczyk, et. al., J. Solid State Chem. 171,
30-37 (2003)
AFM photograph of a mixture of La and Ni powders
MA for 30 h under argon atmosphere.
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Discharge capacities as a function of cycle
number of LaNi5-type negative electrodes made
from nanocrystalline powders prepared by MA
followed by annealing a) LaNi5, b) LaNi4Co, c)
LaNi4Mn, d) LaNi4Al, e) LaNi3.75Mn0.75Al0.25Co0.2
5 (solution, 6 M KOH temperature, 20?C). The
charge conditions were 40 mA g-1. The cut-off
potential vs. Hg/HgO/6 M KOH was ?0.7 V.
M. Jurczyk, et. al., J. Solid State Chem. 171,
30-37 (2003).
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Auger electron spectrum of polycrystalline (left)
and nanocrystalline (right) LaNi4Al alloy versus
sputtering time, as converted to depth. Shown are
the peak-to-peak intensities of lanthanum,
nickel, aluminium, oxygen and carbon. The sample
surface was not cleaned in UHV and is located on
left-hand side.
M. Jurczyk, K. Smardz, W. Rajewski, L. Smardz,
Mater. Sc. Eng. A303, 70-76 (2001).
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TiFe-type phase
XRD spectra of a mixture Ti and Fe powders
mechanically alloyed for different time in argon
atmosphere (a) initial state (elemental powder
mixture), (b) after MA for 5 h, (c) after MA for
20 h and (d) heat-treated at 700 ?C for 0.5 h.
E. Jankowska, M. Jurczyk, J. Alloys Comp. 346,
L1-L3 (2002).
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TiFe-type phase

• Discharge capacity as a function of cycle
  number of electrode prepared with nanocrystalline
  TiFe (a), TiFe0.25Ni0.75 (b) and
  TiNi0.6Fe0.1Mo0.1Cr0.1Co0.1 (c) (solution, 6M
  KOH temperature, 20oC). The charge conditions
  were 40 mA g-1 The cut-off potential vs.
  Hg/HgO/6M KOH was -0.7 V.

• Discharge capacities as a function of cycle
  number of electrode prepared with nanocrystalline
  TiFe1-xNix (solution, 6 M KOH temperature,
  20?C). The charge conditions were 40 mA g-1. The
  cut-off potential vs. Hg/HgO/6 M KOH was ?0.7 V.

M. Jurczyk, et al.. J. Phys. Chem. Sol. 65,
545-548 (2004).
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Mg2Ni type phase
XRD spectra of a mixture of 2Mg and Ni powders
mechanically alloyed for different times in an
argon atmosphere a) initial state (elemental
powder mixture), b) after MA for 90 h and c) heat
treated at 450?C for 0.5 h.
M. Jurczyk, Bull. Pol. Ac. Tech. 52(1) (2004)
47-57.
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PC isotherms at 300oC of hydrogen desorption from
nanocrystalline Mg2-xMnxNi-H alloys
a) x0, b) x0.25 and c) x0.5 .
A. Gasiorowski, W. Iwasieczko, D. Skoryna, H.
Drulis, M. Jurczyk, J. Alloys Comp. 364,
283-288 (2004).
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Table. Structure, lattice parameters, discharge
capacities and hydrogen contents for
nanocrystalline Mg2 Ni-type materials data for
parent polycrystalline Mg2Ni alloy were also
included for comparison (current density of
charging and discharging was 40 mA g-1)
 
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ELECTROCHEMICAL BEHAVIOUR OF POLYCRYSTALLINE AND
NANOCRYSTALLINE ZrV2x-type ALLOYS

• Fig. BET surface area for ZrV2x type
  alloys prepared by different methods

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ELECTROCHEMICAL BEHAVIOUR OF POLYCRYSTALLINE AND
NANOCRYSTALLINE ZrV2x-type ALLOYS

• Fig. Electrochemical pressure-composition
  isotherms for absorption-desorption of hydrogen
  on ZrV2x - type alloys prepared by different
  methods determined at RT

• Fig. Discharge capacity as a function of the
  cycle number of the electrode made of ZrV2x
  type alloys prepared by different methods

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Composite-type nanomaterials

• A new class of electrode materials, composite
  hydride materials, is proposed for anodes in
  hydride based rechargeable batteries.
• These materials were synthesized by mechanical
  mixing of two components
• - 1st with good hydrogen storage properties
• (TiFe-, ZrV2-, LaNi5- and Mg2Ni-type
  type)
• - 2nd used us surface activator (nickel or
  graphite).

Fig. The discharge capacity as a function of
cycle number for MA and annealed TiFe0.25Ni0.75
(a) as well as TiFe0.25Ni0.75/Ni (b) and
TiFe0.25Ni0.75/C (c) composite electrodes
(solution, 6 M KOH temperature, 293 K)
M. Jurczyk, J. Mater. Science 39 (2004) 5271
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Closed cells

• The cyclic behavior of the some nanocrystalline
  RENi5-type alloy anodes was examined in a sealed
  HB 116/054 cell (according to the International
  standard IEC no. 61808, related to the hydride
  button rechargeable single cell) .
• The mass of the active material was 0.33 g.

• Durability of the sealed button cells with
  negative electrodes made from nanocrystalline a)
  Ti(Ni,M) and b) NiCd alloys (the mass of the
  active material was 0.33 g)

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• Conclusion
• In this work, nanocrystalline alloys
  synthesized by mechanical alloying and annealing
  were used as negative electrode materials for
  Ni-MH battery.
• The studies show that
• electrochemical properties of Ni-MH batteries
  are the function of chemical composition and the
  microstructure of used electrode materials

ACKNOWLEDGEMENTS The financial support of the
Polish National Committee for Scientific Research
(KBN) under the contracts No KBN-7 T08D 015 12
(1997-2000), PBZ/KBN-013/T08/02 (2000-2003) and
KBN-8 T10A 001 20 (2001-2004) is gratefully
acknowledged.