The surface modification of carbon felt electrodes has significantly enhanced the energy efficiency of vanadium redox flow batteries. This improvement is largely attributed to the transport properties of these electrodes, previously studied through pore network modeling and X-ray computed tomography imaging [36] [37] [38], as well as other preceding studies [39]. A key component in this development is the carbon-based Gas Diffusion Layer (GDL), known for its stability in acidic environments, high gas permeability, good electronic conductivity, and elasticity under compression. Additionally, it effectively controls the porous structure in a dual-layer GDL setup.
These advancements are not limited to battery applications. For instance, carbon felt has been explored for use in copper plating within hybrid Cu–Fe cells, achieving high plating densities of up to 560 mAh cm−2. However, challenges remain, such as deposit growth near the membrane leading to potential failures [21]. A notable method involves treating carbon felt with nitric acid, followed by immersion in an ethanol suspension of melamine, mixing for 4 hours at room temperature, and then drying at 80°C for another 4 hours.
Innovative uses of carbon felt continue to emerge, such as in the development of three-dimensional (3D) network carbon felt via microwave oxidation, serving as a ZnO support. This is further enhanced by incorporating 30% H2O2-oxidised activated carbon, significantly improving battery performance. The fabrication process of carbon fiber/phenolic composites involves carbon felt and phenolic resin, achieved through vacuum impregnation and compression molding. Moreover, the creation of binder-free carbon nano-networks wrapped around carbon felt has led to a remarkable increase in specific surface area, reaching 161 m2 g−1, a hundredfold increase over pristine carbon felt.
Further research includes the hydrothermal method for growing MoS2 nanosheets directly on flexible/soft carbon felt. Such innovations highlight the versatile applications and significant potential of carbon felt in various high-tech fields, particularly in enhancing the performance and efficiency of energy storage systems like vanadium redox flow batteries.
