Carbon aerogels are porous solid with interconnected carbon particles that exhibit high surface area and electrical conductivity along with structural stability. Previous studies have shown that activated carbon aerogels are promising electrode materials. However, the pores of bulk aerogel do not have sufficient connectivity to allow flow for applications such as flow through batteries, catalysis and capacitive deionization (CDI).
LLNL researchers have developed a process and direct ink writing (DIW) inks for fabricating structured carbon aerogels. This approach gives control over channel size and geometries of organic and carbon aerogels. The 3D printed Resorcinol-Formaldehyde (RF) ink structures are activated to yield high surface area carbon aerogels.
This video demonstrates the DIW process in use with graphene aerogels.
The figures below show the 3D printed carbon aerogels at 5mm, 100 µm, and 4 µm.
The fabrication process developed at LLNL uses 3D printed structures with channels in one direction for bulk flow. Bulk flow allows for lower flow resistance (and thus lower pumping costs) while still having high surface area and high electrical conductivity for efficient salt removal. The 3D printed parts can have a feature size as low as 100 microns.
The process for 3D printing of activated carbon aerogels could be used as a flow electrode with defined channels and geometries to improve the performance of flow-through devices. These applications include flow batteries where bulk flow needs to be orthogonal to diffusion. Other applications are catalysis, filtration/separations, capacitive deionization, capacitors, and energy conversion devices (e.g. hydrogen evolution). LLNL printed graphene based activated carbon aerogels may also be applicable for these applications.
LLNL has filed a patent application for this innovative fabrication process for 3D printing of activated carbon aerogels. Depending on the application, LLNL has supporting portfolios of materials and methods for batteries, catalysis and capacitive deionization.