Zinc-air batteries (ZABs) have been considered as a next-generation battery system with a high energy density and abundant resources. However, the sluggish multi-step reaction of the oxygen is the main...
Aqueous
zinc-based redox flow batteries are promising large-scale
energy storage applications due to their low cost, high safety, and
environmental friendliness. However, the zinc dendritic growth has
depressed the cycle performance, stability, and efficiency, hindering
the commercialization of the zinc-based redox flow batteries. We fabricate
the carbon felt modified with bimodal sized tin and copper clusters
(SCCF) with the electrometallic synthesis in a continuous-flow cell.
The SCCF electrode provides a larger zinc nucleation area and lower
overpotential than pristine carbon felt, which is ascribed to the
well-controlled interfacial interaction of bimodal tin and copper
particle clusters by suppressing unwanted alloy formation. The zinc
symmetric flow battery and the zinc-based hybrid redox flow battery
show the improved zinc plating and stripping efficiency. The SCCF
electrode exhibits 75% improved cycling stability compared to the
pristine carbon felt electrode in the zinc symmetric flow battery.
Notably, the high-voltage aqueous zinc–vanadium redox flow
battery demonstrates a high average cell voltage of 2.31 V at 40 mA
cm–2, showing a Coulombic efficiency of 99.9% and
an energy efficiency of 87.6% for 100 cycles. We introduce a facile
strategy to suppress the zinc dendritic growth, enhancing the performance
of the zinc-based redox flow batteries.
Various redox couples have been reported to increase
the energy
density and reduce the price of redox flow batteries (RFBs). Among
them, the vanadium electrolyte is mainly used due to its high solubility,
but electrode modification is still necessary due to its low reversibility
and sluggish kinetics. Also, an incompatible ion exchange membrane
with redox-active species leads to self-discharge referred to as crossover.
Here, we report a V/Mn RFB using an anion exchange membrane (AEM)
for crossover mitigation and etched carbon felt by nickel–bismuth
(NB-ECF) for the vanadium anolyte. The NB-ECF significantly enhances
the reversibility and kinetics of the V2+/V3+ redox reaction, attributed to inhibited irreversible hydrogen evolution
by the Bi catalyst and increased carboxyl groups by nickel (etching
and NiO catalyst). Notably, the V/Mn cell employed in the NB-ECF maintains
a high energy efficiency of 85.7% during 50 cycles without capacity
degradation at a current density of 20 mA cm–2,
which is attributed to a synergistic effect of crossover mitigation
and facilitated V2+/V3+ redox reaction. This
study demonstrates the novel electrocatalyst design of carbon felt
using two metal species.
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