Decoupling Activation and Transport by Electron-Regulated Atomic-Bi Harnessed Surface-To-Pore Interface for Vanadium Redox Flow Battery.

Vanadium redox flow battery (VRFB) promises a route to low-cost and grid-scale electricity storage using renewable energy resources. However, the interplay of mass transport and activation processes of high-loading catalysts makes it challenging to drive high-performance density VRFB. Herein, we  report a surface-to-pore interface design that unlocks the potential of atomic-Bi-exposed catalytic surface via decoupling activation and transport. The functional interface accommodates electron-regulated atomic-Bi catalyst in an asymmetric Bi-O-Mn structure that expedites the V 3+ /V 2+ conversion, and a mesoporous Mn 3 O 4 sub-scaffold for rapid shuttling of redox-active species, whereby the site accessibility is maximized, contrary to conventional transport-limited catalysts. By in-situ grafting this interface onto micron-porous carbon felt (Bi 1 -sMn 3 O 4 -CF), a high-performance flow battery is achieved, yielding a record high energy efficiency of 76.72% even at a high current density of 400 mA cm -2 and a peak power density of 1.503 W cm -2 , outdoing the battery with sMn 3 O 4 -CF (62.60%, 0.978 W cm -2 ) without Bi catalyst. Moreover, this battery renders extraordinary durability of over 1500 cycles, bespeaking a crucial breakthrough toward sustainable RFBs. This article is protected by copyright. All rights reserved.