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 500 o C, thus with different redox couples, viz. Fe/FeO for 800 o C and Fe/Fe 3 O 4 for 550 o C. 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 800 o C-battery and Fe 3 O 4 -reduction kinetics of RCU for the 550 o C-battery, respectively. Strategies with the goal of achieving a balanced energy capacity and cycle efficiency are also proposed.

Precautions of Using Three-Electrode Configuration to Measure Electrode Overpotential in Solid Oxide Electrochemical Cells: Insights from Finite Element Modeling

“…In this paper, we apply Multiphysics modeling tool to simulate potential distributions in two most popular solid oxide button cell configurations consisting of thin-film electrolyte supported by anode and self-supported thick-film electrolyte. The model parameters, which were previously validated by experimental V-I curves, 24,25 were adopted in the model to illustrate the effects of the geometry and symmetry of each electrode on the potential distribution at the RE. A postprocessing procedure is finally proposed to calculate the electrode overpotential from the measurements.…”

“…Table II. Source terms and expressions [24][25][26] Source terms/Parameters Mathematical expressions Butler-Volmer equation…”

Multiphysics modeling of solid-oxide iron–air redox battery: analysis and optimization of operation and performance parameters

“…This technology has many advantages over conventional counterparts in energy-density, rate-capacity, cost, safety, and system integration. Since the first report in 2011 [13], electrochemical performance optimization [19][20][21][22][23][24][25], new metal-air chemistries [26][27][28][29] and finite-element multiphysics modeling of SOMARB [17,18,[30][31][32][33][34][35][36][37] have been demonstrated. In particular, the basic electrochemical performances and analysis of SOMARB at high temperature (e.g.…”

A Finite Length Cylinder Model for Mixed Oxide-Ion and Electron Conducting Cathodes Suited for Intermediate-Temperature Solid Oxide Fuel Cells

“…Because there is a growing interest in developing low-temperature SOFC cathode materials, [32][33][34][35][36][37][38][39][40][41][42] the MIEC cathode simulated in this study is SrCo 0.9 Nb 0.1 O 3-δ (SCN), which was identified recently as a promising low-temperature SOFC cathode. 36,[43][44][45] For comparison, the stateof-the-art commercial LSCF has also been simulated with the new finite-length model to show the method's validity to MIECs.…”

“…In the present study, two new analytic solutions depicting the oxygen vacancy fraction as a function of frequency, location, geometric factors and oxygen vacancy concentration, as well as physical parameters of the MIEC material, such as the diffusion coefficient of oxygen vacancy, the surface reaction rate, are derived using the actual length of rods constituting the MIEC cathode models. Because there is a growing interest in developing low-temperature SOFC cathode materials, [32][33][34][35][36][37][38][39][40][41][42] the MIEC cathode simulated in this study is SrCo 0.9 Nb 0.1 O 3-δ (SCN), which was identified recently as a promising low-temperature SOFC cathode. 36,[43][44][45] For comparison, the stateof-the-art commercial LSCF has also been simulated with the new finite-length model to show the method's validity to MIECs.…”