Redox Tolerant Solid Oxide Electrolysis Cathode for CO2 and Steam

Abstract

The OxEon team led the development of solid oxide electrolysis cell(SOEC) stacks to convert atmospheric CO2 to pure O2 for the Mars Perseverance Rover mission. The cathode material set was not redox tolerant, therefore a recycle loop was implemented to include reducing CO gas in the stack feed. Since then, OxEon has investigated a combination of materials and engineering solutions to improve redox tolerance of the cathode materials so that 100% dryCO2 (or steam without H2) could be fed directly into a stack without harm. The developed set of cathode materials exhibit remarkable robustness through extreme redox cycling and thermal cycling, as well as higher coking tolerance from preliminary testing. This enables simpler operation (no recycle) and prevents damage from unintended system changes, providing a new solution to operational challenges in SOEC systems. Steam redox tolerance was independently verified from collaboration with Pacific Northwest National Laboratory (PNNL).