Unlocking Interfacial Dynamics of Porous Electrode via Vertical‐Aligned Bismuth‐Nanosheet Decorating for Vanadium Redox Flow Batteries

Abstract Insufficient electrochemical activity and mass transport have been a longstanding issue hindering the development of high‐performance electrode for vanadium redox flow batteries. In this work, vertical‐aligned bismuth‐nanosheets that unlock interfacial dynamics with enhanced catalytic and transport properties are decorated on the electrode surface. The vertical‐aligned structures form highways to guide reactants transport from bulk solution to electrode surface, reducing transport resistance and optimizing active sites utilization. Meanwhile, the bismuth‐nanosheets, dominated by (012) planes with large amounts of unsaturated bismuth atoms, boost the number of electroactive sites and catalytic activity. Full‐cell EIS tests show that the charge transfer resistance and the finite diffusion resistance with prepared electrode are 49.4 and 47.7 mΩ cm −2 , 71.3%, and 6.7% lower than those with traditional electrode. In full‐cell tests, the battery delivers a peak power density of 1340 mW cm −2 and achieves an energy efficiency of 85.8% at 200 mA cm −2 , which is 4.4% higher than that with traditional electrodes. Remarkably, the battery can maintain an energy efficiency of 82.4% at 300 mA cm −2 and be stably cycled for over 2000 cycles with an only 0.0016% efficiency decay per cycle. This work paves a feasible platform to fabricate advanced electrode for vanadium redox flow batteries.