% IMPORTANT: The following is UTF-8 encoded. This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.
@PHDTHESIS{Kiyek:1004334,
author = {Kiyek, Vivien Mirjam},
othercontributors = {Guillon, Olivier and Gonzalez-Julian, Jesus},
title = {{O}xide-based all-solid-state batteries for and from
recycling processes; 1st ed},
volume = {656},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH, Zentralbibliothek, Verlag},
reportid = {RWTH-2025-01368},
isbn = {978-3-95806-806-3},
series = {Schriften des Forschungszentrums Jülich. Reihe Energie
$\&$ Umwelt = Energy $\&$ environment},
pages = {1 Online-Ressource (128, xix Seiten) : Illustrationen,
Diagramme},
year = {2025},
note = {Druckausgabe: 2025. - Onlineausgabe: 2025. - Auch
veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2024},
abstract = {All-Solid-State Batteries (ASSB) are considered to be one
of the most promising future battery technologies due to the
prospect of increased safety and energy density. ASSB can be
categorized into three main classes: Polymers, Sulfides and
Oxides, which are the focus of this work. Ceramic oxides,
among others, are suitable to replace current liquid
electrolytes of Lithium-ion batteries (LIBs), with the
advantage of being the only solid electrolyte (Li7La3Zr2O12,
LLZO) that is stable to Li metal. Li metal as an anode
material provides a higher energy density in the battery and
can overcome the foreseeable limits of liquid electrolytes.
In addition, ceramic oxide solid electrolytes increase
safety due to the high thermal stability of ceramic
materials. Disadvantages of LLZO are the high processing
cost and energy requirements, leading to high embodied
energy due to the multiple long calcination times at high
temperatures. Also, LLZO production requires raw materials
beyond Li, Co, Ni and Mn, which are well-known from the
cathode materials in LIBs. Notably, Ta, and Ga are listed as
critical raw materials. This is one of the main reasons why
recycling is important for both current LIBs and future ASSB
batteries. The current EU directive requires a recycling
rate of $70\%$ of complete batteries in 2030, while
individual materials such as Co, Ni, should have recycling
rates of up to $90\%.$ In the present work, a cost- and
energy-efficient direct recycling route for LLZO components
is developed via re-lithiation of LLZO waste materials by
adding a Li source during heat treatment. Abnormal grain
growth as a possible result of sintering LLZO tapes under Li
excess is analyzed, and the responsible mechanism is
investigated and explained. It is demonstrated successfully
that sintering with Li2CO3 is able to re-lithiate degraded
LLZO: Similar behavior to freshly synthesized LLZO separator
material is observed, while the critical current density
(CCD) is even increased to 0.75 mA cm−2, exceeding the
recently reported values for tapes made from freshly
synthesized LLZO powder in a comparable process. This
re-lithiation route therefore represents the first
successful approach to a direct recycling of LLZO
components, able to save time and cost as well as to
preserve the embodied energy in the LLZO. The second part of
the thesis addresses the high process cost and energy
consumption of LLZO synthesis. Here, a new process route is
developed, where tape casting of precursors powder of LLZO
leads to the formation of LLZO in-situ during the sintering
step. The application of this process onto both the
separator and the composite cathode, a special designed
cathode for example for oxide-solid-state batteries, is then
evaluated. The composite cathode with LCO-LLZO shows highly
promising behavior as the Co-ion diffusion, a disadvantage
of co-sintering of already pre-synthesized LLZO powder
mixtures, that is very hard to avoid, is suppressed in this
new process. Although Al-ion diffusion still occurs, the
general properties of the composite cathodes, such as
density and flatness are very promising. For the LLZO
separator, Ta doping and Ga doping with the new process
route were investigated. Both result in a low-density tape,
however, density can be tuned by adding pre-synthesized LLZO
particles to the slurry. These findings can hence be used as
well to create a porous-dense-porous LLZO layer with the new
process, as the porous LLZO framework represents an
interesting approach for zero-strain electrode layers.
Finally, a recycled precursor material is used in the new
process, which shows first good results for an LLZO
separator tape. This suggests that the new process is
applicable also for recycled raw material, although further
process fine-tuning is required. As a result, the overall
process time is reduced by $65\%,$ while individual steps
are reduced by more than $98\%.$ This translates into a
reduction of the overall throughput time from 40 hours oven
time at the highest temperature (with sintering 45 hours
(LLZO) or 42 hours (LCO-LLZO)) to only 5 hours (LLZO) or 2
hours (LCO-LLZO) at the highest temperature, a significant
advantage for industrial upscaling. Also, energy input is
considerably reduced as the majority of the energy-intensive
heat treatment steps are saved $(80\%).$ This reduction in
time and energy demand ultimately reduces the production
cost of LLZO.},
cin = {524510 / 520000 / 057700},
ddc = {620},
cid = {$I:(DE-82)524510_20140620$ / $I:(DE-82)520000_20140620$ /
$I:(DE-82)057700_20231115$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2025-01368},
url = {https://publications.rwth-aachen.de/record/1004334},
}
guest ::