# Bidirectionally Enhanced Reaction Kinetics in Vanadium Redox Flow Battery via Regulating Mixed-Valence States in Perovskite Electrodes

## TL;DR

A new method to improve vanadium redox flow batteries by modifying perovskite electrodes with Sr and Ce enhances energy storage performance.

## Contribution

A strategy to regulate mixed-valence states in perovskite electrodes for bidirectional enhancement of vanadium redox reaction kinetics.

## Key findings

- Sr doping increases Mn ion valence, lowering the energy barrier for V3+/V2+ redox processes.
- Ce doping boosts VO2+/VO2+ redox processes by increasing oxygen vacancies and charge transfer.
- Modified VRFBs show 67% energy efficiency at 300 mA cm−2 and a 15% increase at 150 mA cm−2.

## Abstract

A selectively regulating strategy for chemical environments of Mn ion activity donors
in LaMnO3 perovskite can bidirectionally enhance vanadium reaction kinetics.The key reactive sites and control steps of perovskite on vanadium redox reactions are
established based on electrochemical tests and theoretical calculation.Sr and Ce doped LaMnO3 as anode and cathode catalysts of the vanadium redox flow
battery (VRFB) , respectively, synergistically improves the VRFB’s energy storage
performance.

A selectively regulating strategy for chemical environments of Mn ion activity donors
in LaMnO3 perovskite can bidirectionally enhance vanadium reaction kinetics.

The key reactive sites and control steps of perovskite on vanadium redox reactions are
established based on electrochemical tests and theoretical calculation.

Sr and Ce doped LaMnO3 as anode and cathode catalysts of the vanadium redox flow
battery (VRFB) , respectively, synergistically improves the VRFB’s energy storage
performance.

The online version contains supplementary material available at 10.1007/s40820-025-02060-0.

Various metal oxide catalysts have been utilized to enhance the electrode reaction kinetics in vanadium redox flow battery (VRFB). However, the determining factor governing their catalysis is still insufficiently understood. Herein, selectively doping of Sr and Ce at La site of LaMnO3 perovskite (LSMO and LCMO) was used to modulate chemical environments of Mn ion activity donors, thereby boosting vanadium redox reaction processes. Sr doping increases the valence state of Mn ions, making it easier for Mn ions to take an electron from the electrode and transfer it to V3+ ions, which lowers the reaction energy barrier of V3+/V2+ redox processes. Conversely, Ce doping decreases the Mn valence and increases the oxygen vacancies, boosting the charge transfer and mass transfer of VO2+/VO2+ redox processes. Theoretical calculation further demonstrates that doping Sr and Ce enhances the vanadium ion’s ability for charge transfer and adsorption. Compared with pristine VRFB, the VRFB with LSMO- and LCMO-modified anode and cathode, respectively, exhibits an excellent energy efficiency (EE) of 67% at a high current density of 300 mA cm−2 and an increased EE of 15% at 150 mA cm−2. This study is critical for promoting fundamental understanding and offering a design strategy for achieving superior-performance metal-based electrocatalysts in VRFB.

The online version contains supplementary material available at 10.1007/s40820-025-02060-0.