Unlocking high-efficiency energy storage: neodymium ferrite perovskite as a cathode catalyst for vanadium redox flow batteries

Abstract

Developing efficient cathode catalysts is pivotal for advancing vanadium redox flow batteries (VRFBs). This study compares hydrothermal (H-NdFeO₃@GF) and sol–gel (SG-NdFeO₃@GF) synthesis of NdFeO₃ perovskite-decorated graphite felt, emphasizing structural and catalytic impacts. H-NdFeO₃@GF features an ABO₃ perovskite framework with Nd/Fe occupying A/B-sites, forming a three-dimensional interconnected network-like mesoporous structure that enhances electron/ion transport and vanadium redox kinetics. At 150 mA cm⁻², H-NdFeO₃@GF exhibits smooth coulombic efficiency (CE) and energy efficiency (EE) profiles over 150 cycles, with a single-cycle capacity of 39.6 Ah L⁻¹ (outperforming SG-NdFeO₃@GF's 26.2 Ah L⁻¹). In rate capability evaluations across 80–250 mA cm⁻², H-NdFeO₃@GF retains ∼65.23% EE even at 250 mA cm⁻², whereas SG-NdFeO₃@GF and traditional GF (TGF) undergo more severe efficiency degradation. For long-cycle stability, H-NdFeO₃@GF achieves a high EE of 78.87% (representing a 12.48% enhancement over TGF and a 4.28% improvement over SG-NdFeO₃@GF) and sustains 1000 cycles at 150 mA cm⁻² with a minimal EE decay rate of 0.00352% per cycle. The work demonstrates that hydrothermal synthesis tailors perovskite crystallinity and carbon-matrix integration, which are critical for exposing active sites and improving durability. These findings underscore H-NdFeO₃@GF as a high-performance VRFB cathode catalyst, offering a strategic pathway for scalable energy storage through synergistic structural and synthetic engineering.