Hybrid direct carbon fuel cell anode processes investigated using a 3-electrode half-cell setup

• Published in: International journal of hydrogen energy Vol. 40; no. 4; pp. 1945 - 1958
• Main Authors: Deleebeeck, L., Arenillas, A., Menéndez, J.A., Kammer Hansen, K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30-01-2015
• Subjects: Anodes; Anthracite; Bituminous coal; Carbon; Carbon dioxide; Carbon monoxide; Cyclic voltammetry (CV); Direct carbon fuel cell (DCFC); Electrochemical impedance spectroscopy; Electrodes; Fuel cells; Half-cell; Nickel; Yttria stabilized zirconia; Carbon monoxide; Half-cell; Cyclic voltammetry (CV); Direct carbon fuel cell (DCFC); Bituminous coal; Carbon dioxide
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2014.12.012

A 3-electrode half-cell setup consisting of a yttria-stabilized zirconia (YSZ) electrolyte support was employed to investigate the chemical and electrochemical processes occurring in the vicinity of a model hybrid direct carbon fuel cell (HDCFC) anode (Ni-YSZ) in contact with a molten carbon-alkali carbonate slurry. Electrochemical testing, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), with and without the Ni-YSZ layer highlighted the promotional effect of the Ni-YSZ anode layer, and revealed the contributions of Ni/NiO, and potentially K/K2O, redox couple(s). Treated anthracite and bituminous coals, as well as carbon black, were tested, revealing similar open circuit potential and activation energies in mixed 96–4 vol% N2–CO2 and 50–50 vol% CO–CO2 environments between 700 and 800 °C. Bituminous coal showed the highest activity, likely associated to a high O/C ratio and hydrogen content. Based on acquired data, a reaction scheme was proposed for processes at the working electrode, including the role of bubble formation in the vicinity of the electrochemically active solid/molten medium interface.
•Electrochemical performance investigated in 3-electrode single-atmosphere HDCFC half-cell configuration.•Carbon black, anthracite and bituminous coal fuels employed in carbon-(Li–K)2CO3 slurries.•Tested by cyclic voltammetry and electrochemical impedance spectroscopy with variable % CO2 (in N2) atmosphere.•Chemical and electrochemical reaction sequences proposed for CO2 (under)saturated slurries.