1 Department of Energy Conversion and Storage, Technical University of Denmark 2 Applied Electrochemistry, Department of Energy Conversion and Storage, Technical University of Denmark 3 Fundamental Electrochemistry, Department of Energy Conversion and Storage, Technical University of Denmark
During co-electrolysis of H2O and CO2 using solid oxide cells (SOCs) the risk of carbon deposition in the Ni-YSZ electrode under high current densities (∼ 2.0 A/cm2) was studied in this work. Five galvanostatic tests were performed at current density between 1.5 and 2.25 A/cm2 and the average conversions of the reactants were no more than 66.8 %. Ni-YSZ electrode delamination and carbon nano-fibers could be observed after test at the Ni-YSZ | YSZ electrolyte interface for two of the cells. Thermodynamic calculation shows that the reactant conversion needed for carbon formation is above 99 %, far above the experimental conversions. The observed carbon formation may be caused by the gas diffusion limitations at high current densities. Carbon nano-fibers were only observed close to the YSZ electrolyte indicating a large overpotential gradient at the TPBs close to the electrolyte. © The Electrochemical Society.
E C S Transactions, 2012, Vol 50, Issue 49, p. 139-151
Carbon; Current density; Deposition; Electrolysis; Electrolytes; Nanofibers; Nickel; Carbon dioxide
Main Research Area:
Pacific Rim Meeting on Electrochemical and Solid-State Science, 2012