Sigracet 39BC is a non-woven carbon paper gas diffusion media with a Microporous Layer (MPL) that has been PTFE treated to 5%. It has a total thickness of 325 um (microns). SGL 39 BC is a great low-cost alternative to conventional woven carbon paper Gas Diffusion Layer (GDL) materials.
2. 特性
The Sigracet Carbon Fiber Paper 39 Series is intended to combine the required production robustness and the excellent performance properties.
Stack developers and assemblers are benefiting from the following greatly improved characteristics:
- Greatly improved homogeneity inter-lot and intra-lot.
- The overall variability has been shown to be better than +/- 10% (2 sigma)
- Greatly improved surface flatness
- Greatly reduced occurrence of faulty spots on a roll
- Best performance under various operating conditions
3. 引用
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1. Gas diffusion layer Sigracet 39BC was obtained from SCI Materials Hub.
SGL Carbon develops and commercializes carbon-based products for Polymer-Electrolyte-Membrane Fuel Cells (PEFC):
- Gas Diffusion Layers (GDL)
- Foils used as separator plates for fuel cells and redox-flow batteries (Expanded Graphite)
GDLs are typically designed as a bilayer structure consisting of a macro-porous backing material (carbon fiber paper support) and a micro-porous, carbon-based layer (MPL). The fibrous backing material governs the mechanical properties of the GDL (behavior upon compression, bending and shear strength, etc.) while the MPL ensures intimate contact to the catalyst layers, protects the delicate proton exchange membrane against perforation and plays an active role with respect to the water management in the cell during operation. There is consensus that this heterogeneous porosity brought about by this structure (hydrophilic/hydrophobic and various pore sizes) is advantageous for the performance.
Sketch of the bilayer structure of Gas Diffusion Layers
Hydrophobic properties in the backing and the MPL are maintained by adding defined amounts of polytetrafluoroethylene (PTFE) to both sublayers. Various types of carbon particles (carbon blacks, graphite) can be used in the MPL in order to produce different levels of hydrophobicity. Furthermore, the MPL can be used as substrate to deposit catalyst particles for the manufacture of gas diffusion electrodes (GDEs).
SGL Carbon has been producing fully-treated SIGRACET gas diffusion layers by reel-to-reel processes since 1999. Carbon paper-type (prepared by wet-laying of chopped PAN-based carbon fibers) gas diffusion layers are the preferred solution since they can be manufactured at high volumes (scalability) and low thickness. The following figures show the whole value chain of GDL manufacturing. All commercially available GDL materials to date are based on carbon fibers derived from polyacrylonitrile (PAN). PAN (co)polymers are processed into precursor fibers by wet-spinning. Subsequent stabilization and pyrolysis yields high tensile (HT) carbon fibers which are sized and chopped to enable suitable processing by means of papermaking technologies.
Carbon Fiber Production
Manufacturing of SIGRAFIL chopped carbon fibers
A primary carbon fiber web is laid by a papermaking technology and subsequent thermobonding. Thereafter, the obtained raw paper is impregnated with carbonisable thermoset resins (with optional addition of carbon fillers), cured and re-carbonized/graphitized. This serves to enhance the mechanical stability and conductivity as well as to adjust the desired porosity level.
Carbon Paper Substrate
Manufacturing route of SIGRACET (carbon paper-based) gas diffusion layer backings
Finishing of GDL comprises hydrophobic treatment of the substrate with PTFE and coating with a microporous layer (MPL).
Finishing Treatment
Finishing treatments of SIGRACET (carbon paper-based) gas diffusion layers
A loading of the substrate with 5% (w/w) PTFE has proven to be sufficient for obtaining a pronounced hydrophobicity. MPLs typically contain 20 to 25% PTFE. This MPL composition has been identified as the optimum ratio for PEMFC performance across a broad range of operating conditions. Mean pore diameters of SIGRACET GDLs are typically in a range from 0.1 to 0.3 μm (Hg-Porosimetry) or 1.5 to 3 μm (calculated from capillary flow porometry). The hydrophobic treatment produces water repellent properties for the substrate and for the MPL (water contact angles by sessile drop method > 130°).
The bipolar membrane (Fumasep FBM) in this paper was purchased from SCI Materials Hub, which was used in rechargeable Zn-CO2 battery tests. The authors reported a strain relaxation strategy to determine lattice strains in bimetal MNi alloys (M = Pd, Ag, and Au) and realized an outstanding CO2-to-CO Faradaic efficiency of 96.6% with outstanding activity and durability toward a Zn-CO2 battery.
In this paper, Vulcan XC-72R was purchased from SCI Materials Hub. Vulcan XC 72R carbon is the most common catalyst support used in the anode and cathode electrodes of Polymer Electrolyte Membrane Fuel Cells (PEMFC), Direct Methanol Fuel Cells (DMFC), Alkaline Fuel Cells (AFC), Microbial Fuel Cells (MFC), Phosphoric Acid Fuel Cells (PAFC), and many more!
An AEM membrane (Sustainion X37-50 Grade RT, purchased from SCI Materials Hub) was activated in 1 M KOH for 24 h, washed with ultra-purity water prior to use.
Graphene oxide (GO) in this paper was obtained from SCI Materials Hub. The authors introduced a Janus Fe3C/N-CNF@RGO electrode consisting of 1D Fe3C decorated N-doped carbon nanofibers (Fe3C/N-CNFs) side and 2D reduced graphene oxide (RGO) side as the free-standing carrier of Li2S6 catholyte to improve the overall electrochemical performance of Li-S batteries.
