High Capacity Redox-Flow Batteries with High Density Suspensions of Spiky Nanostructured Particles

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Nanoparticles with spiky surfaces can store significant charge, enabling energy storage technologies.
• Redox-flow batteries require materials with high charge capacity and good dispersibility.

Purpose of the Study:

• To investigate hedgehog-like iron diselenide (FeSe2) particles (HPs) as charge carriers in aqueous redox-flow batteries.
• To evaluate the performance of HPs for long-duration energy storage.

Main Methods:

• Synthesis of hedgehog-like FeSe2 particles (HPs).
• Characterization of HP dispersions and their electrochemical properties.
• Assembly and testing of a compositionally asymmetric flow cell.

Main Results:

• HPs demonstrated stable aqueous dispersions due to reduced particle-to-particle attraction.
• Shear thinning behavior of HPs was observed, facilitating their use in flow batteries.
• A flow cell with FeSe2 HPs achieved a volumetric capacity of 1.4 mol e/L (36.4 Ah/L) and an open circuit voltage of ~1.0 V.
• Capacity fade was attributed to iron hydroxide-species formation (0.6-5.8%/cycle).

Conclusions:

• Hedgehog-like FeSe2 particles are effective charge carriers for aqueous redox-flow batteries, offering high volumetric capacity.
• Particle shape and high dispersion density contribute to enhanced performance.
• Future work should focus on mitigating capacity fade through particle coatings and electrolyte optimization.