FUEL CELLS

A proton exchange membrane fuel cell is made of a solid electrolyte sandwiched between anode and cathode electrodes.  It generates power electrochemically when hydrogen is passed over the anode and air over the cathode. The by-products are heat and water. (If the hydrogen is derived from fossil fuels, then carbon dioxide is also produced in the process.) 

In order for fuel cells to gain greater market penetration, their cost and performance will need to improve significantly. Materials development, electrode design, speed of manufacturing, and materials selection are critical in meeting these goals.

E2TAC is working on a number of technologies to improve PEM fuel cells:

  • Catalyzation of nanostructures using chemical and vapor deposition processes: Several techniques have been developed to deposit catalyst onto nanostructured support materials.  For example, the polyol process, a scalable conformal coating technique that includes the chemical reduction of metal species in liquid polyols, has been optimized to produce dispersed 4 nm Pt particles, which have been shown to produce the greatest electrochemical activity per unit mass.
  • Novel aerosol assisted deposition (AAD) method: While AAD has been used in other industries, this scalable process was optimized at E2TAC to deposit Pt catalyst on support materials.  By varying process parameters, the amount, size, shape, and orientation of the catalyst particles can be controlled.
  • Optimization of carbon nanotube and carbon nanofiber catalyst supports for electrodes:  Nanostructured carbon can offer many benefits as catalyst supports in fuel cell electrodes, such as corrosion resistance and improved reactant mass transport.  However, these carbon supports can have new issues, such as high hydrophobicity.  E2TAC has developed techniques to maximize the performance of these electrodes.
  • Titanium Nitride catalyst support: TiN offers significant advantages as a fuel cell catalyst support, such as significantly less corrosion than traditional support materials.  E2TAC has developed methods depositing catalyst on TiN and demonstrated its durability in fuel cell operations.
  • Novel fabrication of fuel cells using lithography techniques: Lithography offers two potential benefits to the fuel cell industry.  First, it can be used to create miniature fuel cells useful for portable applications or for powering MEMS devices.  Second, lithography techniques are used to build complicated devices (i.e. computer chips) at relatively low prices at large production quantities.  The same mass-manufacturing techniques are a possible pathway to reducing the cost of fuel cells.
  • Modeling of fuel cell processes on nano-scale to optimize fuel cell structures: Nanoengineering allows us to control electrode structures on the nano-level to maximize catalyst utilization and triple-phase boundary area.  Modeling leads the way to determine structures that will lead to improved performance.
  • Catalyst Coated Membrane (CCM) MEAs: E2TAC has shown that screen printed CCMs can result in higher fuel cell performance than commercial MEAs using a production technique that is fast and scalable.  E2TAC developed a pre-treatment of the Nafion membrane that results in good catalyst adhesion and prevents wrinkling.
  • Reducing contact resistance within a fuel cell stack: Fuel cell stacks are heavily compressed to reduce contact resistance between cell components in order to reduce the amount of electricity dissipated as heat.  Unfortunately, the compression reduces the void volume of the GDL and therefore causes water management issues.  E2TAC had developed technology to reduce contact resistance and allow the stack to be operated with less compression.
  • Coating bipolar plates with water absorbing materials for water management: Water management in a fuel cell is critical: dry conditions can damage the membrane and flooding conditions can degrade performance by blocking reactants.  E2TAC is developing coatings for flow field channels that can buffer the relative humidity of the reactant flows. 
  • Development of MEMS relative humidity sensor: E2TAC has developed RH sensors that are small enough to be placed within the fuel cell flow field to measure the reactant gas RH adjacent to the MEA.  The sensors have fast response time and resist flooding.  The sensors will allow the fuel cell control system adjust the operating conditions and balance of plant to prevent flooding and drying conditions.