Edge-Activated Few-Layer Bismuthene for Ampere-Level Vanadium Redox Flow Batteries

Pursuing high-power-density all-vanadium redox flow batteries (VRFBs) is an attractive approach toward large-scale commercialization in a techno-economic manner. The suboptimal intrinsic activity of conventional catalysts undermines flow batteries' inherent electrode design flexibility, restricting their current density to the low hundreds of mA cm⁻² range and curtailing their technological viability. Here, for the first time, we present a few-layer bismuthene nanoflake (Bi_eneNF) catalyst in the field of redox flow batteries (RFBs). The design strategically exploits the ultra-high intrinsic reactivity of Bi_eneNF's outermost lattice periphery, including individual bismuthene monolayer edges where synergistic nanostructural effects and surface chemistry collectively enhance vanadium redox kinetics and thermodynamics. Notably, this edge-activated catalytic mechanism demonstrates significant intrinsic activity enhancement over bulk bismuth, effectively addressing the dual challenges of deactivation and ohmic losses in flow battery systems. Accordingly, the fueled VRFB reaps an energy efficiency (EE) of up to 80.51% and a reliable catalyst stability over 10 000 cycles at 0.8 A cm⁻², together with an unprecedented peak power density of 3.047 W cm⁻². The demonstrated performance metrics not only establish new benchmarks for VRFB technology but also provide a generalizable strategy for designing high-activity nanostructured catalysts in electrochemical energy storage systems.