Binder-free thin graphite fiber mat sandwich electrode architectures for energy-efficient vanadium redox flow batteries

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, a surface-to-pore interface design that unlocks the potential of atomic-Bi-exposed catalytic surface via decoupling activation and transport is reported. The functional interface accommodates electron-regulated atomic-Bi catalyst in an asymmetric Bi─O─Mn structure that expedites the V3+ /V2+ conversion, and a mesoporous Mn3 O4 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 (Bi1 -sMn3 O4 -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 sMn3 O4 -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 redox flow batteries (RFBs).

Evolution of Vanadium Redox Flow Battery in Electrode

The vanadium redox flow battery (VRFB) is a highly regarded technology for large-scale energy storage due to its outstanding features, such as scalability, efficiency, long lifespan, and site independence. This paper provides a comprehensive analysis of its performance in carbon-based electrodes, along with a comprehensive review of the system's principles and mechanisms. It discusses potential applications, recent industrial involvement, and economic factors associated with VRFB technology. The study also covers the latest advancements in VRFB electrodes, including electrode surface modification and electrocatalyst materials, and highlights their effects on the VRFB system's performance. Additionally, the potential of two-dimensional material MXene to enhance electrode performance is evaluated, and the author concludes that MXenes offer significant advantages for use in high-power VRFB at a low cost. Finally, the paper reviews the challenges and future development of VRFB technology.

Asymmetric Chemical Potential Activated Nanointerfacial Electric Field for Efficient Vanadium Redox Flow Batteries

Constructing active sites with enhanced intrinsic activity and accessibility in a confined microenvironment is critical for simultaneously upgrading the round-trip efficiency and lifespan of all-vanadium redox flow battery (VRFB) yet remains under-explored. Here, we present nanointerfacial electric fields (E-fields) featuring outstanding intrinsic activity embodied by binary Mo2C-Mo2N sublattice. The asymmetric chemical potential on both sides of the reconstructed heterogeneous interface imposes the charge movement and accumulation near the atomic-scale N-Mo-C binding region, eliciting the configuration of an accelerator-like E-field from Mo2N to Mo2C sublattice. Supported with theoretical calculations and intrinsic activity tests, the improved vanadium ion adsorption behavior and charge-transfer process at the nanointerfacial sites were further substantiated, hence expediting the electrochemical kinetics. Accordingly, the pronounced promotion is achieved in the resultant flow battery, yielding an energy efficiency of 77.7% and an extended lifespan of 1000 cycles at 300 mA cm-2, outperforming flow cells with conventional single catalysts in most previous reports.