Adaptive kinetic Monte Carlo simulation of solid oxide fuel cell components

Abstract

Ionic conductivities in solid oxide fuel cell (SOFC) electrolytes yttria-stabilised zirconia (YSZ), calcia-stabilised zirconia (CSZ), gadolinium-doped ceria (GDC) and samarium-doped ceria (SDC) and cathode material lanthanum strontium cobalt oxide (LSCO) are directly calculated using DL AKMC, an adaptive kinetic Monte Carlo (aKMC) program which assumes limited a priori knowledge of the kinetics of systems. The materials were simulated over several milliseconds and over the range of experimentally most relevant temperatures and dopant concentrations (2-18 mol% for doped zirconia, 5-25 mol% for doped ceria and 5-80 mol% for LSCO). Ionic conductivities of the electrolytes at 1000 K are in good agreement with the observed values: CSZ in the range 3×10 −3 -1×10 −2 S cm −1 depending on dopant concentration, YSZ 4×10 −3 -3×10 −2 S cm −1 , GDC 1×10 −2 -5×10 −2 S cm −1 , SDC 1×10 −2 -7×10 −2 S cm −1 . LSCO is predicted to have an ionic conductivity of the order of 10 −2 -10 −1 S cm −1 depending on Sr content. Average activation energies over all migration processes are between 0.4-0.5 eV for the stabilised zirconias and between 0.2 and 0.3 eV for the doped cerias and 0.3 eV for LSCO, in agreement with experiment. aKMC provides a distinct advantage over traditional KMC methods, for which one has to provide a list of system state transitions. Here, all of the state transitions are dynamically generated, leading to a more accurate simulation of the kinetics as the system evolves.

Transport, thermodynamic, and structural properties of rare earth zirconia-based electrolytes by molecular dynamics simulation

“…There is an attempt to show these two effective factors with a plot as can be seen in Figure . According to Figure , temperature dependence of ionic conductivity showed an Arrhenius behavior in accordance with previous studies (see also Figure ) . Ionic conductivity trend toward dopant size exposed different characteristics from low operating temperature to high operating temperature.…”

“…As a result, this pilot study constructed all electrolytes at 8 mol% of rare‐earth dopant. In addition, results of simulation were compared with the reported experiments . Ewald's summation (with precision of 1 × 10 −5 ) represents long‐range electrostatic interactions with full formal ion charges and Born–Mayer–Buckingham potential illustrate short‐range interactions: where A ij , C ij , and ρ ij are the potential coefficients and r ij demonstrates the distance between i and j ions.…”

“…As a result, this pilot study constructed all electrolytes at 8 mol% of rare-earth dopant. In addition, results of simulation were compared with the reported experiments [26][27][28][29][30]. Ewald's summation (with precision of 1 × 10 À5 ) [31] represents long-range electrostatic interactions with full formal ion charges and Born-Mayer-Buckingham potential [32] illustrate short-range interactions:…”

“…Arrhenius plots of ionic conductivity in comparison with experimental data for some studied electrolyte[26][27][28][29][30].…”

New strain states and radical property tuning of metal oxides using a nanocomposite thin film approach

“…The out-of-plane expansion results from vertical strain control of the BSTO (elastic modulus ∼80 GPa) by the stiffer SmO (elastic modulus ∼220 GPa). 13,14 Looking now at the in-plane lattice parameters of BSTO, as already discussed qualitatively for the RSMs of Fig. 2(a), we see that with increasing x, the in-plane parameters of the BSTO increase rapidly upon introduction of a moderate fraction (x = 0.25) of SmO into the films, but then stay approximately the same from x = 0.25 to x = 0.50.…”