Abstract: The actual performance of vanadium redox flow batteries (VRFBs) is still significantly constrained by the slow kinetics and major parasitic reactivity of anode issues. Herein, a B-site management strategy of SrBO₃ (B = Ti, Zr, Hf) perovskites was proposed to promote the anode reaction jointly explored by experiments and first-principle calculations. As the atomic number of B increases, the enhanced polarity of the B-O bond and the increased oxygen defect can boost the adsorption of vanadium ions, while the weakened orbital hybridization of the B-O bond facilitates the charge transfer of anode reaction. Compared with SrTiO₃ and SrZrO₃, oversized particles and deformed crystals of SrHfO₃ reduce its catalysis. Of SrBO₃ perovskites, SrZrO₃ stands out in catalysis, owing to its outstanding combination of high hydrophilicity, large surface area, and desired crystal structure. Further, the VRFB using SrZrO₃ presents a superior energy efficiency (EE) of 63.2% at 300 mA cm^-2 and an increase of 15% in EE compared with the pristine cell at 200 mA cm^-2. This work lays the foundation for building the connections between the structural and compositional flexibility and the tunable perovskite properties desirable for vanadium redox reactions.

Key words: Vanadium redox flow battery, Perovskite, Catalyst, Reaction kinetics, Anode