Catalytic activity of materials for solid oxide fuel cells

Contact:

Senior Researcher Martin Søgaard, Department of Energy Conversion and Storage (msqg@dtu.dk)

 

Figure 1: Working principle of a fuel cell. On the cathode side oxygen from the air is reduced to oxide ions, which are transported through the electrolyte. On the anode side of the fuel cell the oxide ions combine with hydrogen and form water. The electrons needed for the redox processes are transported through an external circuit as electric power.

A solid oxide fuel cell (SOFC) is a device that converts chemical energy into electric energy with very high efficiency. SOFCs have several advantages compared to the traditional ways of generating electrical power. These include high efficiency, scalability, fuel versatility and low noise operation. If the current operation temperature of the solid oxide FC (approximately 700 - 800°C) can be lowered, less expensive materials can be used in a SOFC stack increasing the likelihood of commercialization of the technology. When reducing the temperature the electrochemical activity of the electrodes decreases together with the ionic conductivity of the electrolyte. Especially the activity of the electrode (cathode) that reduces oxygen to oxide ions is severely decreased when decreasing the temperature. It is therefore crucial to obtain knowledge on the catalytic activity of materials used as cathodes and the materials ability to conduct oxide ions. One method for doing this is a method known as electrical conductivity relaxation (ECR). With the ECR method the electrical conductivity is measured upon a sudden change in the surrounding conditions. By monitoring the change in electrical conductivity with time it is possible to deduce information about the catalytic activity of the given material.

 

The present project consists of two parts. In the first part a Comsol-Matlab model will be developed that describes the method of ECR. Comsol is a very powerful tool for simulating different kinds of physics using a finite element method. The developed model will be compared against existing analytical and simplified numerical solutions available in-house and in the literature. In the second part of the project the method of electrical conductivity relaxation will be applied to specific materials already available in the department. Based on the measurement it will be established in the investigated materials are suitable for use as cathodes for solid oxide fuel cells.

 

The project takes place at DTU Risø Campus. Transport expenses will be covered.