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@PHDTHESIS{Reppert:848095,
author = {Reppert, Thorsten},
title = {{H}erstellung und {C}harakterisierung von
{L}ithiumlanthanzirkonat-{F}unktionsschichten für
{L}ithium-{F}estkörperbatterien},
volume = {425},
school = {Universität Bochum},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek Verlag},
reportid = {FZJ-2018-03374},
isbn = {978-3-95806-331-0},
series = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
Umwelt / Energy $\&$ Environment},
pages = {vii, 187 S.},
year = {2018},
note = {Universität Bochum, Diss., 2017},
abstract = {The aim of this work is to produce a lithium ion conducting
solid electrolyte as basic material for application in new
efficient energy storage such as solid state batteries. If
the liquid electrolyte in lithium ion batteries (LIB) is
replaced by a self-supported solid electrolyte, safety,
durability and energy density can be improved. Tape casting
is a suitable method to process aforementioned
self-supported solid electrolytes. The focus is on the
powder synthesis of lithium lanthanum zirconate
(Li$_{7}$La$_{3}$Zr$_{2}$O$_{12}$;LLZO)which can be
optimized by substitution with elements like Al, Ta or Y.
These substituted LLZO compositions show improved mechanical
and (electro-) chemical stability, and have the highest
lithium ion conductivity for all oxide electrolytes.
Furthermore, a comparison between the synthesis by solid
state reaction and by spray pyrolysis is made. In respect of
the influence of process parameters, the microstructure,
mechanical properties and the ionic conductivity of sintered
pellets are examined. Spray pyrolysis has proved to be a
scalable method which was used to synthesize Al-LLZO in a
purely cubic phase. Moreover, in this work it is shown that
Ta-LLZO has the most suitable cross-section profile in
matters of sinterbility, the mechanical properties (hardness
and elastic modulus) and lithium ion conductivity. Another
main focus is the characterization of LLZO’s crystal
structure. Several LLZO electrolytes have been sintered in
an air or an argon atmosphere and were subsequently examined
by complementary characterization methods in the context of
a cooperation with the $\textit{Oak Ridge National
Laboratory}$ (ORNL). Next to the crystal structure,
especially the atomic positions as well as the occupancies
of lithium were determined for several LLZO compositions. A
water-free synthesis of LLZO powders was proven by inelastic
neutron scattering and in addition, a lithium-proton
exchange was prevented. Furthermore, neutron backscattering
is used to determine LLZO’s self-diffusion constants and
related activation energies. Thus, it could be shown that
the tetragonal LLZO phase doesn’t contribute significantly
to lithium ion’s self-diffusion. Spray pyrolyzed Al-LLZO
was used for a tape casting slurry’s development. A
defect-free thin electrolyte film was cast and used for
sintering experiments. The microstructure of sintered solid
state electrolytes still is not sufficient for a
self-supported solid electrolyte. Though, a promising
candidate for continuing tape casting is tantalum
substituted LLZOsynthesized by spray pyrolysis. Its suitable
particle size distribution and sinterbility enable the
fabrication of self-supported LLZO functional layer for
solid state lithium ion batteries.},
cin = {IEK-1},
cid = {I:(DE-Juel1)IEK-1-20101013},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/848095},
}