Enhancing the Catalytic Kinetics of Electrodes by using a Multidimensional Carbon Network for Applications in Vanadium Redox Flow Batteries

Composite graphite felt (GF) electrodes modified by using a carbon network are fabricated for vanadium redox flow batteries (VRFBs). The electrodes are derived through the in situ polymerization of p-phenylenediamine and phytic acid on GF fibers, followed by high-temperature calcinations performed in an inert atmosphere. The composite electrodes exhibited higher electrocatalytic activities for the VO²⁺/VO₂ ⁺ and V²⁺/V³⁺ redox species compared with the original GF electrode. The peak potential was reduced by 357 mV, which could be attributed to the increased number of active sites and diffusion pathways; the energy efficiency of the composite electrode increased by 6 % (current density: 200 mA cm⁻²). Based on the above-mentioned structural design, a battery containing the composite electrodes exhibited excellent cycling stability without any obvious efficiency decay after 1000 cycles, indicating its applicability for large-scale VRFBs.