PAN-Based Carbon Felt vs Viscose-Based: How to Choose the Right Electrode Material

PAN-Based Carbon Felt vs Viscose-Based: The Precursor Difference

The defining distinction is the precursor fiber, which controls carbon yield, graphitizability, and final ash content. PAN-based carbon felt is made from polyacrylonitrile staple fiber that is needle-punched into a nonwoven body, then carbonized at around 1,000 C. When the same body is graphitized above 2,000 C, it becomes PAN-based graphite felt.

Viscose-based carbon felt uses rayon, a regenerated cellulose fiber. Cellulose carbonizes at roughly 20 to 30 percent yield, versus about 50 percent for PAN, so viscose felts shrink more and finish with a finer, denser texture after the same heat treatment. The difference in yield is the single biggest reason viscose products cost less per kilogram but behave differently at the surface.

PAN-Based Carbon Felt for High-Temperature Insulation and Electrode ApplicationsThis carbon felt, derived from polyacrylonitrile and carbonized at 1200°C, offers high temperature resistance up to 1500°C and excellent electrical conductivity, making it suitable for insulation and electrode use in demanding environments.View Product →

• Carbon yield: about 50 percent for PAN, 20 to 30 percent for viscose
• Graphitization: PAN forms more ordered graphite layers, lowering resistivity
• Ash content: high-purity viscose grades reach lower ash after washing
• Needle-punch control: PAN staple fibers punch more uniformly at low densities

PAN-Based vs Viscose-Based: How the Properties Compare

At equal thickness and bulk density, PAN-based graphite felt outperforms viscose-based graphite felt in tensile strength, while viscose-based felt shows lower ash content and better flexibility. The practical consequences are easy to measure in a stack.

In a VRFB, in-plane resistivity of the electrode directly affects ohmic losses. Graphitized PAN felt can sit at 3 to 6 mOhm-cm, while viscose grades typically rest at 5 to 10 mOhm-cm. For high-temperature insulation, thermal conductivity matters more; PAN graphite felt conducts heat better, so it is a weaker insulator. Electrode surface chemistry has a measurable effect on VRFB power density, which is why the felt finishing step matters as much as the precursor.

How to Choose PAN-Based or Viscose-Based Felt for Flow Battery Electrodes

For vanadium redox flow batteries, PAN-based graphite felt is the workhorse electrode because it provides the highest accessible surface area per gram and the strongest cycling stability.

Electrode felt quality and electrode surface chemistry dominate system power density. A felt with uneven thickness or high ash content creates local hotspots and capacity fade. Before ordering, ask the factory for a measured thickness map, a bulk density range, and a plot of in-plane resistivity.

Electrode felt quality can shift zinc-bromine battery performance by several points, which is why the felt supplier should share process control data for every batch.

PAN-Based Graphite Felt for Extreme High-Temperature and Electrochemical UseGraphitized at 2200°C, this PAN-based felt withstands temperatures up to 3200°C, providing superior conductivity and chemical inertness for high-performance insulation and electrode applications.View Product →

High-Temperature Insulation and Purity-Critical Applications

If the felt must stay in a high-purity furnace or retort, viscose-based graphite felt is the safer choice because its rayon-derived texture sheds less fiber and holds lower ash.

Viscose-based graphite felt is a staple in vacuum furnace insulation, rare-earth melting, and semiconductor-grade thermal zones. The rayon precursor yields a fine, closed surface that resists fiber shedding, which matters when particulate contamination can ruin a melt. PAN-based felt is preferred when the insulation layer also needs to carry current or resist mechanical wear.

Viscose-Based Graphite Felt for Low Thermal Conductivity and InsulationMade from viscose rayon, this graphite felt features low density and thermal conductivity (≤0.2W/m·k), ideal for furnace insulation and ablation-resistant materials in semiconductor and high-temperature processes.View Product →

• Vacuum furnace hot-zone insulation
• Rare-earth and superalloy melting furnaces
• Semiconductor crystal-growth insulation
• Flexible sealing and packing in high-temperature equipment

Purchasing Considerations: Tolerances, Cost, and Lead Time

The final choice usually comes down to thickness tolerance, ash specification, and price per square meter, not to which felt is universally better.

PAN-based felt costs more per square meter because the precursor price is higher and graphitization takes more energy. Viscose-based graphite felt becomes cost-competitive at thicknesses above 5 mm. When you issue an RFQ to Jiaxing Naco New Material Co., Ltd., state the felt type, thickness tolerance, bulk density target, and a maximum ash limit; the factory can adjust needle-punching and graphitization temperature to meet those targets.

1. State the felt type: PAN-based, viscose-based, carbonized, or graphitized
2. Give thickness tolerance, such as +/- 0.5 mm, and bulk density range
3. Set an ash limit, for example max 100 ppm for high-purity grades
4. Specify width and whether you need slitting or die-cut shapes