Views: 0 Author: Site Editor Publish Time: 2025-10-28 Origin: Site
Graphite felt is made by weaving carbon fibers and has a conductivity of up to 10-100 S/cm, which can efficiently transfer electrons in electrode reactions. Compared to traditional metal electrodes, it is lightweight and corrosion-resistant, making it suitable for long-term operation.
The high specific surface area (5-50 m²/g) of graphite felt provides sufficient active sites for redox reactions. For instance, in vanadium redox flow batteries, the conversion rate of vanadium ions (V²⁺/V³⁺, VO²⁺/VO₂⁺) is enhanced by 20%-30% due to the catalytic effect of graphite felt (Journal of Power Sources, 2019).
Its porous structure (with a porosity of over 90%) evenly distributes the electrolyte, reducing concentration polarization. Experimental results show that the energy efficiency of the battery using graphite felt can reach 75%-85%, which is higher than that of graphite plates (60%-70%).
The fiber diameter of graphite felt is usually 7-15 micrometers, and they are interwoven to form a three-dimensional network. After the electrolyte penetrates into the pores, the active substances undergo oxidation-reduction reactions on the surface of the fibers, and electrons are conducted through the carbon fibers to the external circuit.
In the long-term cycle, the chemical inertness of graphite felt can resist corrosion by acidic electrolyte (such as an environment of 1.5-2 M H₂SO₄), and its lifespan exceeds 10,000 cycles. Moreover, surface modification (such as nitrogen doping) can further reduce the reaction overpotential.
The price of commercial graphite felt is approximately $50 - $100 per square meter. Researchers are developing low-cost carbon-based alternative materials (such as recycled carbon fibers).
Gradient pore design can enhance mass transfer efficiency. For instance, the upper large pores (>50 μm) facilitate the flow of electrolyte, while the lower micropores (<10 μm) increase the reaction area.
Summary: Graphite felt, due to its unique physical and chemical properties, plays a crucial role in the efficient operation of flow batteries. In the future, it is necessary to continuously optimize its comprehensive performance by integrating materials science and engineering.
