ASSEMBLY: What are the latest trends in fuel cell design and manufacturing?

Bennett: Ongoing trends include reduction or elimination of balance-of- plant components, increased power density and increased system lifetime. With reduced humidification needs, less equipment is required for water management. Additionally, fuel cell designs—specifically for stack components—continue to investigate newer membrane polymers, electrode materials, and designs for a reduction in catalyst levels and increase in power density, leading to reduced stack cell count, all toward overall system cost reduction. Increased system lifetimes through more durable materials and optimized system operation also leads to decreased capital costs.

ASSEMBLY: What is the most challenging fuel cell component to assemble?

Bennett: The most important component, often referred to as the heart of the fuel cell system, is the stack. A fuel cell stack incorporates a number of membrane electrode assemblies (MEAs), each of which is integral to the performance of the unit. These MEAs need to perform under rigorous conditions. For effective performance, sealing materials between the various components must withstand both chemical and mechanical stresses. Poor seal performance has significant impacts on transport properties and cannot be understated.

ASSEMBLY: What types of materials are typically used to manufacture fuel cells? Are any new materials being studied?

Bennett: Fuel cell materials and their selection are a function of the type of fuel cell under consideration. In the case of polymer electrolyte membrane (PEM) stack components, standard materials include gasket and sealing materials, gas diffusion layers, electrodes, ion conducting membranes and bipolar plates. For phosphoric acid (PAFC) stacks, many of the same materials are needed, although the ion conducting electrolyte is phosphoric acid. These materials may require more robust materials, due to higher temperature and corrosive environment of the cell. Fuel cell manufacturers are always evaluating newer materials that can provide benefits ranging form greater durability to achieving increased conductivity and improved cost-performance metrics.

ASSEMBLY: Are most fuel cells still manually assembled? Have any new automated production processes been developed?

Bennett: With increasing volume requirements of the various components going into a fuel cell, many manufacturers are designing in automation. This allows for increased productivity and process repeatability, among other benefits.Much of the drive for automation comes with increasing volumes of the various inputs to a fuel cell. Many companies utilize robotics and continuous methods to achieve higher throughputs. 3M has developed unique roll-to-roll capability in the manufacturing of its MEA products, enabling the company to meet year 2020 and beyond volume projections.

ASSEMBLY: How much closer are we to fuel cell commercialization in the auto industry? Is this technology still “10 years away?”

Bennett: Automotive OEMs continue to develop improved fuel cell systems. Early introductions at low volumes are scheduled in the next few years for several automakers. The Department of Energy publishes annual benchmark performance data and associated cost targets that the OEMs strive to meet. These targets include material, processing and assembly costs. A key driver to [reducing costs] remains, among others variables, increase in power density, raw material costs of electrode catalysts and high-cost gas diffusion layer materials.

ASSEMBLY: What challenges still need to be addressed before fuel cells can be cost-effectively mass-produced?

Bennett: Market adoption of fuel cell technology continues to progress. The cost of fuel cells needs to be able to stand without governmental subsidies, which translates to lower precious metal loading and higher manufacturing volumes.3M has ongoing efforts to address opportunities at improving a number of aspects of design and manufacturing as they relate to PAFC and PEM technologies.