High and durable performance of an external-manifold designed reversible solid oxide cell stack

摘要

A 5-cell reversible solid oxide cell stack in external-manifold design is fabricated with planar cells with an active area of 169 cm2, Ni-Y2O3 stabilized ZrO2 (Ni-YSZ) support, Ni-YSZ functional anode (fuel electrode), YSZ electrolyte, and YSZ-composite cathode (air electrode). It is operated at various temperatures in different atmospheres. In fuel cell mode at 750 degrees C with H2 fuel and air oxidant, the stack generates 407 W (481.7 mW cm-2, 81.4 W per cell) at 0.68 A cm-2. In electrolysis mode, with H2-55% H2O at 750 degrees C, the current density at the thermo-neutral voltage (6.45 V) is-0.340 A cm-2, and concentration polarization starts at around-0.3 A cm-2. They are-0.592 A cm-2 and above-0.50 A cm-2, respectively, under 80% H2O and 800 degrees C. H2 production rate increases from 88 NL h-1 to 209 NL h-1, accordingly. Using H2-80% H2O for fuel electrode at 800 degrees C, the stack performs at around 7.0 V and-0.5 A cm-2 for up to 900 h without gas leaking and cell delamination and with more severe metal oxidation at the spots where the SUS430 interconnect contacts with Ni foam current collector on the fuel electrode side.

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