Using known materials, scientists at the Georgia Institute of Technology in the USA have designed a new electrode architecture for solid oxide fuel cells (SOFCs) that overcomes many of the limitations of existing electrodes.
SOFCs are an exciting and promising source of power, which are able to provide clean and renewable energy and are scalable to suit a number of applications. They are essentially larger versions of batteries that have a solid electrolyte in which the charge carriers are oxide ions. Oxygen is introduced at the anode, which is reduced to oxide ions which then migrates across the solid electrolyte to the cathode. Fuel, such as hydrogen, is introduced at the cathode, which is oxidised by the oxide ions.
However, improvements to materials and components are still necessary, particularly for designing SOFCs that can operate at lower temperatures.
One of these challenges is to improve electrode design, which is expected to demonstrate fast ionic/electronic transport, rapid surface electrochemical reactions, chemical and physical compatibility with other components of the fuel cell (important considering fuel cells typically operate at many hundreds of degrees Celsius) and stability at high temperatures and oxidising environments.
Although La0.85Sr0.15MnO3±δ (LSM) and La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) are commonly used cathode materials, they each have their limitations; LSM has poorer ionic conductivity and surface exchange kinetics than LSCF whilst LSCF has poor surface catalytic properties and also has inadequate longevity.
Meilin Liu and co-workers, however, have combined both materials in a new electrode architecture. Their design, which consists of a LSCF backbone coated with a thin-film of LSM, combines the materials’ desirable properties of high conductivity and excellent stability and catalytic activity, respectively.
This new architecture, the authors say, could be cheaply and easily applied to current commercial fuel cells and could also represent a net decrease in cell cost, due to the improvements in performance and stability.
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