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@PHDTHESIS{Hamzelui:1015555,
author = {Hamzelui, Niloofar},
othercontributors = {Figgemeier, Egbert and Wiemhöfer, Hans-Dieter},
title = {{I}nvestigation of active materials and polymeric binders
in silicon-based negative electrodes for lithium-ion
batteries},
volume = {191},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {Institute for Power Electronics and Electrical Drives
(ISEA), RWTH Aachen University},
reportid = {RWTH-2025-06437},
series = {Aachener Beiträge des ISEA},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2025; Dissertation, Rheinisch-Westfälische
Technische Hochschule Aachen, 2024},
abstract = {Silicon (Si) is one of the most promising anode active
materials for the next-generation high-energy-density
lithium-ion batteries (LIBs), due to its high theoretical
capacity compared to state-of-the-art graphite (Gr) anode
material. However, the utilization of Si-based anodes in
LIBs is limited due to the excessive volumetric changes of
Si particles upon lithiation and delithiation. These volume
changes lead to particle pulverization, resulting in
mechanical degradation, unstable solid electrolyte
interphase (SEI), and short cycle life of the battery. To
improve the performance of Si-based electrodes, different
strategies have been applied. The co-utilization of Si and
Gr active materials (Si/Gr composite electrodes) and the
development of polymeric binder systems with unique
chemistries are two of the most effective strategies to
enhance the performance of Si-based anodes. This thesis
focuses on the development of Si-based anodes by optimizing
the electrode formulations to achieve better mechanical and
electrochemical performance. In the first part of this work,
a systematic investigation of Si and Gr active material
content in the anode, ranging from pure Gr to pure Si, has
been conducted using a dual binder system of lithium
poly(acrylic acid) (LiPAA) and carboxymethyl cellulose
(CMC). The ratio of binders (LiPAA:CMC) was optimized
according to the ratio of active materials (Si:Gr). The
electrochemical performance of the electrodes was
investigated versus lithium (Li) metal and nickel manganese
cobalt oxide (NMC622). Post-mortem scanning electron
microscopy (SEM) with energy dispersive X-ray analysis (EDX)
was performed on the optimized Si/Gr after
lithiation/delithiation at different cycle numbers and
C-rates to investigate the changes in morphology and Si
particle degradation. The electrochemical performance of the
high-capacity Si/Gr and NMC622 cell was investigated and
optimized at high temperatures to integrate the cell into a
PV-battery system. In the second part of this work, the
optimized Si/Gr anode was further studied using sustainable
and environmentally friendly natural polymeric binders.
Chitosan biopolymers with different degrees of acetylation
(DA) and polymerization (DP) were utilized as binders in the
Si/Gr anode. After further fine-tuning of the anode
formulation with chitosan binders, cross-linking of chitosan
with citric acid monohydrate, combined with the development
of a free-standing electrode, resulted in improved
electrochemical performance of the cell. The
electrochemically cycled Si/Gr anodes were analyzed using
X-ray photoelectron spectroscopy (XPS) to study the surface
chemistry of electrodes with and without chitosan binder.
Moreover, the effect of various parameters of the binder
solution, such as pH, was investigated for the
state-of-the-art LiPAA binder. The mechanical and
electrochemical performance of the Si/Gr anodes, as well as
the cross-linking of LiPAA with CMC, sodium alginate (SA),
and tragacanth gum (TG), was studied. All binders were
characterized by Fourier transform infrared spectroscopy
(FTIR) and thermogravimetric analysis (TGA), and the
mechanical properties of the electrodes were measured by a
90-degree peel test. Based on the electrochemical and
mechanical properties of the Si/Gr anodes, the LiPAA binder
with a neutral pH exhibited superior performance, especially
at higher C-rates. Overall, this work indicates the
importance of the anode's chemistry and formulation and its
direct effect on the electrochemical performance of the
LIBs.},
cin = {618620 / 614500},
ddc = {621.3},
cid = {$I:(DE-82)618620_20170609$ / $I:(DE-82)614500_20201203$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2025-06437},
url = {https://publications.rwth-aachen.de/record/1015555},
}
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