It is essential to boost the catalytic activity and cycling stability of the electrode for the ultra-long-term operation of vanadium flow battery (VFB). Herein, we report a novel hierarchical electrode by coating carbon spheres on the graphite felt (CS/GF) employing silicon dioxide nanospheres as templates and phenol formaldehyde resin as carbon sources. CS/GF possess larger surface areas and more defects than the thermally activated graphite felt, leading to better wettability and more active sites. As a result, the electrochemical activity and kinetic reversibility of the CS/GF electrode toward the VO 2 + /VO 2+ and V 3+ /V 2+ redox couples are promoted. Meanwhile, the novel carbon layer-confined structure ensures the superior durability of the CS/GF electrode during the ultra-long-term cycling test. The VFB assembled with CS/GF electrode exhibits outstanding rate performance at current densities of 50–300 mA cm −2 as well as excellent stability over 5000 charge-discharge cycles at a high current density of 150 mA cm −2 . The facile method in this work provides a new idea for developing efficient and durable VFB electrodes.
A simple and effective method to roughen graphite felt (GF) by using manganese oxide as an etching agent has been developed for vanadium redox flow battery (VRFB) application. The specific surface area of roughened GF (R-GF) prepared at the optimized conditions reaches 8.49 m 2∙ g -1 , 7 times larger than that of the pristine one (P-GF), and more oxygen-containing functional groups are formed on the roughened surface. The experimental results show that the R-GF has higher peak current, smaller peak potential separation and lower charge transfer resistance than those of P-GF and GF treated with air oxidation (O-GF). The VRFB with R-GF electrodes exhibits a strongly enhanced electrochemical performance in terms of energy efficiency and utilization ratio of electrolyte at different current density. The large specific surface area with abundant oxygen-containing functional groups of R-GF has been shown to be extremely beneficial for improving the kinetics of the VRFB.
危险品化学品经营许可证（带存储）