Trichome-like Carbon-Metal Fabrics Made of Carbon Microfibers, Carbon Nanotubes, and Fe-Based Nanoparticles as Electrodes for Regenerative Hydrogen/Vanadium Flow Cells

Abstract

Regenerative hydrogen/vanadium flow cells (RHVFCs) require electrode architectures combining electrochemical, catalytic, and mechanical properties across nano-, micro-, and milliscales. The use of current carbon-based electrodes can lead to poor electrolyte utilization, slow kinetics, and rapid electrode deterioration, resulting in suboptimal electrochemical performance and hindering RHVFC's commercial viability.To address this, we here demonstrate the application of trichome-like carbon-metal fabrics (CMFs) made of carbon microfibers, carbon nanotubes, and iron-based nanoparticles as both a catalytic layer and electrode in RHVFCs by evaluating their key figures of merit. CMFs in combination with commercial carbon cloth not only offer a high power density ∼645 mW cm −2 (∼0.82 V) but also excellent cycling performance at 150 mA cm −2 , yielding nearly 100% energy efficiency and a high average discharge capacity of ∼23 Ah L −1 (∼90% electrolyte utilization). These electrochemical results together with electrode microstructural features assessed by X-ray tomography and projected cost analysis represent a step change in the design and development of tailored electrodes capable of withstanding RHVFC cycling conditions without compromising electrochemical performance.

Lightweight Carbon–Metal-Based Fabric Anode for Lithium-Ion Batteries

“…The CMF sample was scanned on a ZEISS Vectra 520 for determining the surface microstructures of interest. The specimen was scanned at a voltage of 80 kV, a power of 7 W, an exposure time of 20 s, and a minimum of 10× over 1601 projections as reported previously …”

“…To prepare the CMF trichome electrodes, Fe­(acac) 3 powder was added in ratios of 40 wt % relative to PAN and mixed for 24 h at 55 °C as described elsewhere . The as-prepared precursor solution was then transferred to a syringe and pumped into the electrospinning needle at 1.5 mL·h –1 by a syringe pump integrated with an electrospinning machine (Bioinicia LE-50).…”

“…The specimen was scanned at a voltage of 80 kV, a power of 7 W, an exposure time of 20 s, and a minimum of 10× over 1601 projections as reported previously. 16 2.4. Slurry Cast Electrode Preparation.…”

“…Recently, we reported a novel electrode architecture resembling trichomes consisting of micron-sized carbon fibers, carbon nanotubes (CNTs), and Fe nanoparticles based on electrospinning and pyrolysis (termed as carbon–metal fabric or CMF), demonstrating their advantageous performance in a Zn-air battery as free-standing electrodes . The trichome-like electrodes were also employed as carbon catalyst layers for hybrid hydrogen/vanadium flow cells successfully, albeit being coupled with graphene-modified carbon paper/cloth materials to endure the harsh operating conditions of high flow rates (50–100 mL·min –1 ) and current densities (100 mA·cm –2 ) in the constant presence of 5 M sulfuric acid . In spite of such promising performances in the aforementioned energy storage devices, understanding the behavior of these trichome-like morphologies in lithium-ion battery applications, compared to traditional slurry cast electrodes, remains a research gap.…”

Review—Flow Batteries from 1879 to 2022 and Beyond

“…Advantages of broad pore size (or fiber diameter) distribution in RFB electrodes were reported recently by others as well. [275][276][277][278] Benefits of spatial porosity distribution within RFB porous electrodes (i.e. smaller pores near the membrane and larger pores near the flow fields) have also been demonstrated.…”