High Performance Solid Oxide Electrolysis Cells with Hierarchically Porous Ni-YSZ Electrode

Abstract

In solid oxide electrolysis cells (SOECs), the microstructure of the fuel electrode (Ni-YSZ) has a great influence on the electrochemical performance of cells. In this study, novel hierarchical Ni-YSZ electrode with open channel pores has been fabricated by freeze-drying tape casting (FDTC). The microstructure of the Ni-YSZ electrode was characterized using SEM, mercury intrusion, 3D X-ray microscopy and gas permeability, showing that Ni-YSZ electrode fabricated by FDTC has large porosity and low tortuosity factor, which are beneficial for gas transport. SOECs with the Ni-YSZ electrode fabricated from FDTC display excellent performance ( -0.95 A cm-2 with 1.3 V at 750 oC) in the electrolysis mode, which is twice of that with the conventional sponge-like Ni-YSZ electrode fabricated from dry-pressing (DP). Furthermore, hierarchically porous Ni-YSZ electrode is more obvious in the electrolysis mode than the fuel cell mode, probably due to the slower diffusion of H2O and CO2 than H2.