GWANGJU, South Korea, July 19,
2024 /PRNewswire/ -- Due to rising environmental
concerns, global energy production is shifting from fossil fuels to
sustainable and renewable energy systems such as solar and wind
power. Despite their advantages, they have two significant
weaknesses: volatile power production and irregular supply. Hence,
they are augmented with energy storage systems (ESSs). Lithium-ion
batteries are at the forefront of ESSs but are prone to fires due
to flammable electrolytes and lithium-based materials. The flowless
zinc-bromine battery (FLZBB), which uses non-flammable
electrolytes, is a promising alternative, offering
cost-effectiveness and a simple battery platform.
A FLZBB consists of a positive electrode, a negative electrode,
an electrolyte, and a separator to keep the electrodes apart.
Unlike conventional zinc-bromine batteries, the electrolyte in
FLZBB does not need to be pumped and is instead held in a gel-like
container. Graphite felt (GF) is widely used as an electrode in
many redox batteries due to its stability in acidic electrolytes.
However, in FLZBBs, bromine and polybromide ions are formed within
the GF-positive electrode during charging. These active materials
can escape and diffuse uncontrollably to the negative electrode,
causing self-discharge, which severely affects performance and
lifespan. Many studies have explored approaches to suppress this
crossover phenomenon, however, self-discharge remains a major issue
for FLZBBs.
To address this issue, a team of researchers led by Professor
Chanho Pak and including integrated
M.S. and Ph.D. student Youngin Cho
(first author) from the Graduate School of Energy Convergence,
Institute of Integrated Technology at Gwangju Institute of Science
and Technology, Korea, developed a novel nitrogen-doped mesoporous
carbon-coated thick GF (NMC/GF) electrode. Their study was made
available online on April 22, 2024,
and published in Volume 490 of the Chemical Engineering
Journal on June 15, 2024.
The researchers fabricated the NMC/GF electrodes using a simple,
cost-effective evaporation-induced self-assembly method. In this
method, a pristine GF felt was coated with precursor materials and
mixed in a solvent, followed by drying and curing. When applied to
an FLZBB, the new electrodes effectively suppressed the crossover
of the active materials and prevented self-discharge. This success
was attributed to the mesopores present on the GF fibers in the
NMC/GF electrodes.
Prof. Pak explains, "The NMC coating on the GF electrodes
introduced mesopores with strategically embedded nitrogen sites,
which served as a stronghold, capturing the bromine and bromine
complexes in the positive electrode, suppressing bromine crossover
and self-discharge phenomena. Moreover, this coating made
the originally hydrophobic pristine GF electrodes ultrahydrophilic,
improving interfacial contact with the electrolyte in the aqueous
electrolyte and enhancing electrochemical performance.
Additionally, it allowed the incorporation of abundant oxygen and
nitrogen species, which improved bromine reaction speeds, further
boosting performance."
The FLZBB with NMC/GF electrodes demonstrated excellent
Coulombic and energy efficiencies of 96% and 76%, respectively, at
a current density of 20 mA cm-2, as well as a high-rate
areal capacity of 2 mAh cm-2. Furthermore, the battery
exhibited unprecedented durability, with charge/discharge cycling
stability extended to over 10,000 cycles. Also, the thick GF
electrode used can potentially reduce the overall price of the
battery.
Highlighting the significance of this achievement, Prof. Pak
says, "The development of FLZBB positive electrode, which
maintains long-term operation over 10,000 cycles with high
efficiencies, will accelerate the development of stable ESSs and
eco-friendly energy conversion in the long term. Moreover, NMC/GF
positive electrode can also be used for other aqueous
batteries."
Reference
Title of original paper: Achieving
unprecedented cyclability of flowless zinc-bromine battery by
nitrogen-doped mesoporous carbon on thick graphite felt
electrode
Journal: Chemical Engineering Journal
DOI: https://doi.org/10.1016/j.cej.2024.151538
About the Gwangju Institute of Science and Technology
(GIST)
http://www.gist.ac.kr/
Contact:
Chang-Sung Kang
82 62 715 6253
380565@email4pr.com
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SOURCE Gwangju Institute of Science and Technology