Technology

Our technical capabilities originated in the development of a proprietary SOFC technology at our subsidiary company, Franklin Fuel Cells (FFC). That company’s mission is to commercialize highly efficient, sulfur-tolerant and multi-fuel-capable solid oxide fuel cells using its proprietary membrane electrode assembly (MEA) designs in both planar and tubular configurations. That pursuit, which began with FFC’s incorporation in 2001, resulted in the creation of a unique team of scientists, engineers and technicians along with a unique portfolio of intellectual property and technical expertise in the areas of: ceramic tape casting; thick film paste manufacturing; planar and tubular SOFC manufacturing and testing; screen-printing; high- temperature firing and materials properties characterization, among others. These capabilities, which were originally developed to serve the singular objective of commercializing proprietary SOFC technology, are now available to our industrial, research and development, and academic customers through Franklin Advanced Materials.

SOFC Materials

Seven-plus years and many millions of dollars in development work at FFC produced a solid suite of products. These range from complete cells (in both planar and tubular form), half cells for use in electrode development, green and fired Yttria-stabilized Zirconia (YSZ) and Scandia-stabilized Zirconia (ScSZ) electrolyte supports, to anode and cathode screen-printable electrode and current collection pastes. These MEA components and materials represent both state-of-the-art conventional designs (i.e. NiO based anodes and LSM or LSCF based cathodes), as well as FFC’s proprietary-electrode intellectual property.

FFC’s Direct Oxidation SOFC

Some of the most significant challenges to the commercialization of fuel cells have included high system cost, poor reliability, and the limitation of having to operate on pure hydrogen rather than more-readily-found and easily-stored fuels such as gasoline, diesel, or bio-fuels. While conventional SOFCs are considered to be fuel flexible – which is certainly a true statement relative to the highly limited hydrogen-only capability of Polymer Electrolyte Membrane (PEM) fuel cells – this fuel flexibility only extends to sulfur-free hydrogen, methane and carbon monoxide – hardly the most convenient suite of fuels. Conventional SOFCs are further challenged by anode poisoning from sulfur in concentrations greater than about 1 part per million (ppm) and anode failure due to oxidation from exposure to air, as can happen during the fuel-starved conditions possible at start-up, shut down or refueling events.

 In response to these obstacles to fuel cell commercialization, FFC developed Direct Oxidation SOFC (DOSOFC) technology that employ all-ceramic anodes which have been shown to operate directly on complex, sulfur-containing hydrocarbon fuels such as diesel and military JP-8 without fouling from carbon formation or sulfur poisoning. This all-ceramic anode is also completely reduction-oxidation (redox) tolerant, capable of high power density, and can be incorporated into both planar and tubular cell configurations. What this means to the fuel cell system developer is that: a) the de-sulfurizer component of the system may be deleted; b) the fuel reformer may be eliminated or greatly simplified; and c) system startup, shut down and refueling events can not only be simplified but also have a lessened impact on component reliability. These system benefits translate to higher fuel efficiency, lower system cost and higher product quality and reliability.

Reformate Fueled SOFC

In addition to FFC’s line of unique DOSOFC materials, we have developed and made available for purchase full cells and half cells (in planar and tubular forms) based on the more conventional multi-layer Nickel cermet anode, 8 mole % YSZ or 6-to-10 mole % ScSZ electrolyte, and either LSM or LSCF multi-layer cathode. Please feel free to discuss your specific application with one of our development engineers for assistance determining the optimal cell configuration.

Anode, Electrolyte and Cathode Materials

The same materials that we use to produce all of our mechanically-robust and high-performance fuel cells are available for purchase separately. Green (un-fired) anode and electrolyte tapes in a range of chemistries, formulations and thicknesses can be produced to your specifications or may be available “off the shelf” in combinations that are known to work and have been fully characterized in our laboratory. We also provide cathode paste – by the gram, kilogram or ton – for LSM and LSCF in chemistries appropriate for functional, as well as current collection, layers. A full range of contact pastes (NiO, Ag, Ag-Pd, Au, Pt and LSM) are also available.

Ceramic Tapes (Tape Casting or Slip Casting)

Tape casting is the process by which a precisely-combined and expertly-dispersed mixture of inorganic materials (most commonly: ceramic powders and organic materials that may include binders, plasticizers, dispersants and other rheological modifiers) are deposited onto a carrier tape – most commonly a coated polyester – to an even thickness controlled by means of a “doctor blade”. After drying, this relatively thin (thicknesses between 2-5 µm and 1 mm are common), flexible “tape” is removed, cut to a desired shape and fired. Alternatively, this unfired, or “green”, tape can be processed again to deposit another layer on its surface, or laminated using a process like hot isostatic pressing (HIP) to produce a multi-layer structure that, when appropriately formulated, laminated and fired, will produce a flat, strong, intimately-connected, engineered material with a desired set of properties.

Franklin AM – via FFC – has more than seven years of experience designing some of the most complex tape systems ever produced. We routinely cast, laminate and fire combinations of both dense and porous tapes. These tapes ultimately produce structures that combine highly-porous layers (50 to 70% porosity) adjacent to functionally-dense ones, combining them into a single part that fires flat – flat enough to screen print without fear of cracking.

This ability to design slurry, tape casting, lamination and firing processes in a way that compensates for inherent incompatibilities between the properties of dense and porous ceramic materials and dissimilar ceramic materials is one of our company’s core competencies and a unique technical capability that we offer to our customers.

You will find in our store tape systems for SOFC applications that include a multi-layer NiO/6ScSZ anode and a 6ScSZ or 10ScSZ electrolyte in thicknesses of 5 to 20 µm. These systems fire flat when processed according to our recommendations. You will also find many other material formulations and compositions. Please let us know what your fuel cell, sensor, LTCC, HTCC or LED application requires and let us design a tape system that meets your specifications at the lowest possible manufacturing cost.

Thick Film Paste Processing

Screen printable pastes, also known as inks, are produced by precisely mixing metal and / or ceramic powders (optionally, glass powders and inorganic oxides), along with organic materials, and thoroughly combining these by a mixing process commonly known as three-roll milling (3RM).

Franklin AM brings together state-of-the-art, hydraulically-controlled three-roll mill equipment, experienced manufacturing and product engineers and technicians, along with designs for six sigma (DFSS) and ISO 9001 quality procedures, to the art of producing thick-film paste products that are second to none in performance and quality. Our paste products include SOFC cathodes, anodes, and electrolytes, and metallization products for LTCC, HTCC, and solar cell applications.

Manufacturing Materials

Here, you can also find materials for use in your own tape casting, paste manufacturing or firing processes. These include a line of proprietary Terpineol- and Texanol-based vehicles and thinners. We can also provide porous and dense setter / cover plate materials in alumina and zirconia compositions that are custom made to your specific dimensional requirements.