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@ARTICLE{Gercek:1025078,
author = {Gercek, Candeniz and Börner, Markus and Winter, Martin},
title = {{E}nabling the {P}roduction of {H}omogeneous {H}igh-{L}oad
{P}ositive {E}lectrodes by {T}ailoring the {E}lectrode
{F}ormulation – a {C}onductive {A}dditive and {S}olvent
{A}pproach},
journal = {Meeting abstracts},
volume = {MA2023-01},
number = {2},
issn = {1091-8213},
address = {Pennington, NJ},
publisher = {Soc.},
reportid = {FZJ-2024-02666},
pages = {532 - 532},
year = {2023},
note = {Hierbei handelt es sich lediglich um einen Abstract.},
abstract = {The automotive industry experiences a substantial change
due to electrification of major parts of the transportation
system by using lithium ion batteries (LIBs). To facilitate
this transition, low cost and high energy density LIBs
produced under the most sustainable conditions possible are
required. These objectives are amongst others strongly
related with the positive electrode. Thus, in order to
achieve enhanced energy densities on cell level, the
application of high-load positive electrodes for various
cell systems ranging from lithium ion to lithium metal
batteries is inevitable. However, to ensure high lithium ion
mobility within thick composite electrodes and to obtain
maximized capacity utilization, it is crucial to tailor the
electrode microstructure. With regard to the production,
detrimental effects like binder-migration can occur upon
drying of thick electrodes inducing inhomogeneous
distribution of binder and conductive additive within the
electrode coating. Beyond that, the effect of lateral
coating shrinkage resulting in electrode cracking during
drying plays an increasingly significant role with
increasing electrode thickness.The application of high solid
contents (SC) during electrode paste processing can widely
suppress the effects of binder migration and crack
formation.[1,2] However, elevated SCs result in increasing
paste viscosities leading to practical limitations for
homogeneous electrode coating. By using nano-scale and
micro-scale spherical, linear and three-dimensional
conductive additives like carbon microfibers (CMF) or
conductive graphite (CG) in addition to carbon black (CB),
the adjustment of an appropriate paste viscosity can be
facilitated. The addition of more carbonaceous additives
acting as conductive additive as well as processing additive
resolves the rheological requirements for an electrode paste
with $80\%$ SC and significantly influences the pore
structure of the electrode. Thus, tailoring active and
inactive components is crucial to enable processing of high
SC electrode pastes with an appropriate viscosity in
conjunction with the production of thick electrodes
exhibiting an optimized pore structure benefiting the
electrochemical performance. The additional introduction of
carbon nanotubes (CNTs) leads to the formation of segregated
networks providing more stability within the electrode and a
favorable electrode microstructure. Moreover, the use of
CNTs benefits the electrochemical performance by immensely
boosting electronic conductivity resulting in higher rate
capability and increased capacity retention. The various
electrode formulations containing up to three different
conductive additives were compared to the benchmark
formulation without further additives in terms of electronic
conductivity, adhesion, pore structure and electrochemical
performance. Different electrode formulations were
investigated and compared regarding the composite electrode
adhesion strength, electronic conductivity, microstructure
and electrochemical performance over 400 cycles in a coin
cell setup with a graphitic negative electrode. However, the
optimized formulation containing CNTs enables the production
of thick positive electrodes exhibiting significantly higher
areal capacities up to 8 mAh cm-2 with superior
electrochemical properties and higher content of active
material in the formulation resulting in higher energy
densities on cell level. In a next step, the state-of-art
processing solvent N-Methyl-2-pyrrolidon (NMP) was targeted
with the goal of replacing NMP with a non-toxic solvent. The
influence of a co-solvent on the electrode paste viscosity
was investigated to further increase the SC, lower
production costs and enable improved environmental
benignity.A comprehensive study on tailoring the
rheological, structural and electrochemical properties by
processing additives is presented. The increase of the SC to
$80\%$ is a first step towards the reduction of the ecologic
and economic footprint for LIB production while
simultaneously enabling electrodes with high areal
capacities exhibiting increased rate capability and capacity
retention enabled by the addition of CNTs.[1] J. Seeba, S.
Reuber, C. Heubner, A. Müller-Köhn, M. Wolter, A.
Michaelis, Chemical Engineering Journal Volume 402, 2020,
125551.[2] L. Ibing, T. Gallasch, P. Schneider, P. Niehoff,
A. Hintennach, M. Winter, F. M. Schappacher, Journal of
Power Sources 423, 2019, 183–191.},
cin = {IEK-12},
ddc = {540},
cid = {I:(DE-Juel1)IEK-12-20141217},
pnm = {1221 - Fundamentals and Materials (POF4-122)},
pid = {G:(DE-HGF)POF4-1221},
typ = {PUB:(DE-HGF)16},
doi = {10.1149/MA2023-012532mtgabs},
url = {https://juser.fz-juelich.de/record/1025078},
}