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

Abstract

Cyclic voltammetry (CV) Bituminous coal Carbon monoxide Carbon dioxide a b s t r a c t 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/K 2 O, 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 96e4 vol% N 2 eCO 2 and 50e50 vol% COeCO 2 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.

Comparative study of durability of hybrid direct carbon fuel cells with anthracite coal and bituminous coal

“…It is deemed that the highest activity of bituminous coal is associated with its high ratio of oxygen/carbon and hydrogen content 21 . Predtechensky et al…”

Hydroxide electrolyte direct carbon fuel cells—Technology review

“…2,[20][21][22] Since recently, cells which combine two electrolytes (molten carbonate and solid oxide), so-called hybrid DCFCs, have also been developed. [23][24][25][26] The overview diagrams of functioning of DCFCs that used individual electrolytes are presented in Figure 2.…”

“…There are four basic types of electrolytes: molten carbonates, solid oxide ceramics (mostly Yttria‐Stabilized Zirconia), water solutions of hydroxides, and molten hydroxides . Since recently, cells which combine two electrolytes (molten carbonate and solid oxide), so‐called hybrid DCFCs, have also been developed . The overview diagrams of functioning of DCFCs that used individual electrolytes are presented in Figure .…”

Recent Development and Applications in Electrodes for URFC

“…The fuel cell operation requires that the oxygen GDL have a hydrophobic property to prevent water flooding, on the other hand, water electrolysis requires that the GDL have a hydrophilic property to supply water to the oxygen electrode. Several methods have been demonstrated to overcome these problems by using specially designed electrodes with complex multi-layer structures or membranes with internal fluid passages [20]. However, while these methods overcome some of the basic problems, neither of these approaches leads to a cell (stack) with adequate performance for use in applications.…”