Analysis of Performance Limiting Factors in Solid-Oxide Iron-Air Redox Battery Operated with Different Redox Couples

Abstract

The present computational study investigates the factors limiting the performance of a newly developed solid oxide iron-air redox battery (SOMARB) operated at 800 and 500oC, thus with different redox couples, viz. Fe/FeO for 800oC and Fe/Fe3O4 for 550oC. The multiphysics model established is considered high fidelity since it has been validated by experimental data obtained under conditions similar to the simulations. The effects of current density, initial porosity of redox cycle unit (RCU), distance between Reversible Solid Oxide Fuel Cell (RSOFC) and RCU, and depth of discharge on the battery’s performance have been systematically studied. It is found that the performance limiting factor is the electrolysis electro-kinetics of RSOFC for the 800oC-battery and Fe3O4-reduction kinetics of RCU for the 550oC-battery, respectively. Strategies with the goal of achieving a balanced energy capacity and cycle efficiency are also proposed.