Constructing Structural Defects on Perovskite Surface to Accelerate Electrode Kinetics for Vanadium Redox Flow Batteries

Due to the inadequate electrochemical properties of the original graphite felt (GF), catalysts are needed to improve the performance of vanadium redox flow batteries (VRFBs). Introducing structural defects including oxygen vacancy defects and A-site defects in perovskite AZrO₃ (A = Ca, Sr, Ba) are used to promote the kinetics of vanadium ion redox reactions. The A-site ions are selectively etched and release lattice oxygen to form oxygen vacancies by acid treatment. Structural defects add additional active sites to enhance the adsorption capacity for vanadium ions and promote redox reactions. The electrochemical properties are influenced by a combination of the number of defects and the type of defects. In summary, SrZrO₃ shows the best electrochemical performance. SrZrO₃-GF cell achieves 64% energy efficiency (EE) at 200 mA cm^-2, representing a 14.3% improvement over the pristine. The material also demonstrates excellent stability over 500 cycles in long-term testing. The strategy of introducing structural defects on the perovskite surface provides valuable insights and new strategies for catalysts in VRFBs, paving the way for more efficient battery systems.