Computer modelling of oxide ion conductors
Lead PI:Prof. Graeme Watson
Abstract:Solid oxide fuel cells (SOFCs) are devices which generate electricity from a variety of sources, such as hydrogen or hydrocarbons. This electrolytic conversion can reach efficiencies of up to 85%. Current electrolyte technology used in solid oxide fuel cells requires high operational temperatures which makes them expensive to build and impractical in all but very large scale facilities. Our goal is therefore the study of conductivity in yttrium-doped ceria (Ce1-xYxO2-x/2,) which can be used at intermediate temperature regimes. In this project we seek to rationalize the effect of aliovalent doping on the conductivity of CeO2 using atomistic and ab initio modelling methods, the results of which will be compared with experimental data gathered by Dr Stephen Hull’s group at ISIS in the UK. We have developed an interatomic potential for yttrium-doped ceria from DFT calculations, in collaboration with Prof Paul Madden’s group in Oxford. This potential, which allows for the description of dipole polarizabilites in the species being simulated, will then used in molecular dynamics simulations that can be run for time periods in the nano second scale; this is a clear advantage over full ab initio simulations of the systems in question, which using current hardware make simulations beyond 10ps impractical. Our calculations will allow the determination of properties including ionic conductivity, vacancy formation energies, residence times and structural data, such as the radial distribution function, which are key to our understanding of materials for the next generation of SOFCs.