Mechanistic Studies of Liquid Metal Anode SOFCs II: Development of a Coulometric Titration Technique to Aid Reactor Design

Improved understanding of the operation of liquid metal anode solid oxide fuel cells (LMA-SOFCs) is required to progress this promising energy conversion technology. In order to facilitate analysis and interpretation, initial studies have been carried out with a simple system in which hydrogen is used as the fuel and the liquid metal electrode is operated in a potential region where it effectively behaves as an 'inert' solvent for dissolved gases. A model for the processes taking place in a liquid tin anode (LTA) supplied with hydrogen has previously been reported which identified a key parameter, the Dynamic Oxygen Utilisation Coefficient, z(combining overline), important for understanding the operation and design of these systems. This parameter serves a similar role to the Damköhler number, widely applied in chemical reaction engineering to relate the chemical reaction rate to the transport phenomena rate. This paper describes the development of a method, named Anodic Injection Coulometry (AIC), to determine z(combining overline), together with an example of its application.