Remarkably Improved Durability of Ni–Co Dispersed Samaria-Doped Ceria Hydrogen Electrodes by Reversible Cycling Operation of Solid Oxide Cells

Abstract

We have examined the durability of a double-layer hydrogen electrode, consisting of a samaria-doped ceria (SDC) scaffold with highly dispersed Ni–Co nanoparticles as the catalyst layer and a thin current collecting layer of Ni–yttria-stabilized zirconia (YSZ) cermet for a reversible solid oxide cell (R-SOC). When steam electrolysis was performed continuously (solid oxide electrolysis cell, SOEC) at 800 °C, a rapid, large increase in the ohmic resistance of the hydrogen electrode side was observed. In contrast, the durability of the hydrogen electrode was found to be improved remarkably by reversible cycling operation between SOEC and solid oxide fuel cell (SOFC) modes, i.e., virtually no degradation over 1200 h. This could be ascribed to a stabilization of the microstructure of the hydrogen electrode. It was also found that the durability of the oxygen electrode, which was based on a composite of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and SDC with an SDC interlayer, was also improved by the reversible cycling operation, compared with a slight degradation in the continuous SOEC operation.

Ni migration in solid oxide cell electrodes: Review and revised hypothesis

“…An electrolyte supported SOEC with such a fuel electrode was operated during 23,000 h in the steam electrolysis mode, of which 20,000 h were with −0.9 A cm −2 at 850 • C. The Ni-CGO electrode had no visible damage of the H 2 electrode after testing [49]. Uchida et al [50] examined durability of a double-layer fuel electrode, which consisted of a samaria-doped ceria scaffold with dispersed ca. 7 vol.% Ni 0.9 Co 0.1 + 10 vol.% Ni nanoparticles as catalyst layer.…”

Changes in Microstructure of Ni–Co Dispersed Samaria-Doped Ceria Hydrogen Electrodes for the Improved Durability via Reversible Cycling Operation of Solid Oxide Cells

“…The thicknesses of the CCL and CL were approximately 5 μm and 15 to 20 μm, respectively. 26,28 A mixed solution of Ni(NO 3 ) 2 and Co(NO 3 ) 2 was impregnated into the CL through the CCL to form Ni 0.9 Co 0.1 nanoparticles after the reduction. The LSCF-SDC oxygen electrode was prepared on the SDC interlayer (thickness = ca.…”

“…After conditioning the cell with repetitive galvanostatic cycles, the steadystate IR-free polarization curves of the DL-H 2 and O 2 electrodes with area-specific ohmic resistance R ohm were measured by the current interruption method, as described in previous work. 28 The durability of the electrodes was examined by protocols shown schematically in Fig. 1.…”

“…8,13,18,19 We have engaged in the research and development of highperformance electrodes with novel architecture for the R-SOC. 16,17,[20][21][22][23][24][25][26][27][28][29] Very recently, we found that the durability of a double-layer H 2 (DL) electrode, consisting of a SDC scaffold [samaria-doped ceria (CeO 2 ) 0.8 (SmO 1.5 ) 0.2 ] with highly dispersed Ni 0.9 Co 0.1 nanoparticles as the catalyst layer (CL) and a thin current-collecting layer (CCL) of Ni-YSZ cermet, was greatly improved via reversible cycling operation between the SOEC and SOFC-modes. 28 In the present work, we focus on the stabilization mechanism of the microstructure of the CL in our H 2 electrode via reversible cycling operation.…”

Experimental Results of a 10/40 kW-Class Reversible Solid Oxide Cell Demonstration System at Forschungszentrum Jülich

“…In recent years, Solid Oxide Cell (SOC) technology has gained significant attention. [1][2][3][4][5][6][7][8][9] Besides the activities in the pure fuel cell (SOFC) or electrolysis (SOEC) operation, significant successes have also been achieved in the development and simulation of reversible Solid Oxide Cells (rSOC). The Technical University of Denmark (DTU) showed that this technology can convert electricity via electrolysis into hydrogen, whereby this hydrogen can later be converted back into electrical energy on demand.…”