am6b04723_si_001.pdf (2.01 MB)
Electrochemically Scavenging the Silica Impurities at the Ni–YSZ Triple Phase Boundary of Solid Oxide Cells
journal contribution
posted on 2016-06-28, 00:00 authored by Youkun Tao, Jing Shao, Shiyang ChengSilica
impurity originated from the sealing or raw materials of the solid
oxide cells (SOCs) accumulating at the Ni–YSZ triple phase
boundaries (TPBs) is known as one major reason for electrode passivation.
Here we report nanosilica precipitates inside Ni grains instead of
blocking the TPBs when operating the SOCs at |i|
≥ 1.5 A cm–2 for electrolysis of H2O/CO2. An electrochemical scavenging mechanism was proposed
to explain this unique behavior: the removal of silica proceeded through the reduction
of the silica to Si under strong cathodic polarization, followed by
bulk diffusion of Si into Ni and reoxidation of Si in the Ni grain.