Effect of applied voltage on the current density of CO2 electrolysis in high temperature

Abstract

Reductions in CO2 emission can be achieved directly through CO2 capture and storage (CCS), a method that is particularly effective when used with large CO2 emitters such as electrical power plants and iron and steel mills. Solid-oxide electrolysis presents an alternative means of reducing CO2 that can use some of the CO2 captured by CCS as a source of electrolysis. In addition, unused heat generated by steelmaking and through renewable sources (e.g., solar and wind) can be utilized for high-temperature electrolysis. This study investigated the effect of applying a high voltage of between 2.5 and 4.0 V to common electrolytic materials (YSZ and Pt), and found that although the initial current density of a new cell is very low, it increases drastically upon application of a high voltage. The results of FE-SEM observation revealed that the interface between the YSZ and Pt electrode moves into the YSZ by about 70 μm, and consists of a nano- and micro-porous structure that reduces the resistivity and gas diffusivity.