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

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.

Automated summary

This article introduces a 5-cell reversible solid oxide cell stack in an external-manifold design, using planar cells with specific components and operating at different temperatures and atmospheres. The stack shows efficient power generation in fuel cell mode and increased H2 production rate in electrolysis mode. It also demonstrates long-term stability without gas leaking and cell delamination, despite metal oxidation in certain contact areas.