3D microstructural characterization of Ni/yttria-stabilized zirconia electrodes during long-term CO₂ electrolysis

Abstract

The solid oxide electrolysis cell (SOEC) is one of the most promising energy conversion devices due to its high efficiency and gas flexibility. However, its performance degradation in long-term operation...

Integrated 3D modeling unravels the measures to mitigate nickel migration in solid oxide fuel/electrolysis cells

“…The variation in f surf was controlled by multiplying A and B by a common factor of f surf / f 0 surf , where f 0 surf is the reference surface energy. 19 A tuning function of W = −9.35 W ad + 4.69 was extrapolated to control the variation in W ad by setting a reference contact angle under OCV conditions to 115°, 14 and another contact angle under high polarization φ = 0.1 V to 18°, as shown in Fig. S0 in the ESI † 21 .…”

“…The observations in our previous work indicated that current plays a major role in driving Ni migration, while the contribution of the gas diffusion pathway is minor. 14 The Ni–YSZ contact angle gradient caused by the current could play an important role in driving the Ni surface diffusion in different gas environments. To verify the influence of the contact angle gradient along the Ni–YSZ interface, the simplified PF simulations were rerun by introducing continuous gradients for both f surf and W ad along the x -axis by using ∇ W = −0.01/voxel and ∇( f surf / f 0 surf ) = 0.01/voxel, while W = 4 and ( f surf / f 0 surf ) = 0.75 were set at the center indicated by the dashed line, as shown in Fig.…”

“…10–13 It is well known that Ni coarsening occurs during operation in FC and EC modes and under open circuit voltage (OCV) conditions. 14–16 There are few studies dealing with the investigation of Ni migration in the FC mode. Menzler et al reported the phenomenon of Ni migration toward the electrolyte in an SOFC after more than 10 years of operation.…”

“…However, we recently observed Ni migration during the EC operation of CO 2 , suggesting that the Ni(OH) x species may not be the main contributor to Ni migration. 14 Cheng et al 22 proposed a theory based on a hypothesis, that the dynamic redox of Ni, combined with the coarsening and gas transport processes, could be related to Ni migration. However, the 1D steady-state model proposed showed limitations, mainly regarding the lack of the description of the microstructure of the electrode and the consideration of the transient effect of charge transport.…”

Revealing the Reaction Mechanism of CO2/H2O Coelectrolysis on Perovskite-Based Cathode Materials

“…Conventional Ni-YSZ is widely used as electrode materials for SOEC. Nevertheless, the application of Ni-YSZ for the CO 2 electrochemical reduction reaction is hindered by problems such as impurity gas poisoning, redox instability, and coke deposition at high CO concentration. − Perovskite oxides with good mixed electron–ion conductivity (MEIC) are ideal alternative cathodes for coelectrolysis using SOEC. For instance, Cho et al combined microkinetic analysis and density-functional theory calculations to obtain a volcano plot of the electrocatalytic activity of coelectrolysis, confirming that Fe, Ru, and Co had superior activity than Ni in the CO 2 /H 2 O coelectrolysis .…”