Partial internal short circuit resulting from the Ce4+/Ce3+ redox reaction is currently one of the most critical
issues that hinder the practical application of solid oxide fuel cells (SOFCs) with doped ceria electrolytes. In
this work, a new strategy utilizing a Sr diffusion induced in situ solid-state reaction to generate a blocking
layer to prevent Ce0.8Sm0.2O1.9 (SDC) from reduction is proposed for the first time. As a proof of concept,
Ni-SrCe0.95Yb0.05O3d is deployed as a Sr source for the electron-blocking interlayer and was evaluated as
an anode for SDC-based SOFCs. A thin interlayer composed of SrCe1x(Sm,Yb)xO3d and SDC is formed in
situ during the sintering process of the half cell due to the interdiffusion of metal cations, and the interlayer
thickness is highly dependent on the sintering temperature. The high-resolution TEM results indicate that
the SrCe1x(Sm,Yb)xO3d perovskite phase is generated and coated on the SDC grains, forming an
SDC@SrCe1x(Sm,Yb)xO3d core–shell structure. The SrCe1x(Sm,Yb)xO3d phase effectively suppresses
the Ce4+/Ce3+ redox reaction and hence eliminates electronic conduction through the electrolyte
membrane. Consequently, the OCVs of the fuel cell are significantly improved after incorporating the
electron-blocking interlayer and increase with increasing the interlayer thickness. The OCVs of the cell
sintered at 1250 C reach 0.962, 0.989, 1.017, and 1.039 V at 650, 600, 550, and 500 C, respectively.
The present results demonstrate that Ni-SrCeO3-based composites are promising alternative anodes for
CeO2-based SOFCs towards enhanced working efficiency at high operating voltages.