•Bilayered electrolyte membranes composed of BZCY and SDC were evaluated for SOFCs with high OCVs.•The electron-blocking ability of BZCY layer depends on its exact location in the fuel cell.•BZCY located at the anode side could protect SDC from reduction and eliminate internal short circuit.•A thin BZCY layer is critical for achieving high power performance.Bilayered electrolyte membranes composed of BaZr0.1Ce0.7Y0.2O3−δ (BZCY) and Ce0.8Sm0.2O2−δ (SDC) were evaluated for solid oxide fuel cells (SOFCs), and the influence of the membrane architecture on the cell performance was investigated. The electrochemical testing results showed that the electron-blocking ability of BZCY layer depends on its exact location in the fuel cell. The partial internal short circuit was nearly totally eliminated for the cell with BZCY layer located at the anode side, and the corresponding cell exhibited a high open circuit voltage (OCV) of 1.0 V at 700 °C. In contrast, the cell with BZCY layer located at the cathode side still exhibited significant internal short-circuit behavior. The different electron-blocking ability can be ascribed to the atmosphere-dependent charge transport behavior of BZCY. The present results demonstrate that the bilayered BZCY/SDC membrane with BZCY layer located at the anode side is a promising electrolyte for highly efficient low-temperature SOFCs. Besides, the BZCY layer should be as thin as possible to achieve desirable power performance for the fuel cell.

Acceptor-doped barium cerate is considered as one of the state-of-the-art high temperature proton conductors (HTPCs), and the proton conductivity of such HTPCs is heavily dependent on the dopant. In this work, a codoping strategy is employed to improve the electrical conductivity and sinterability of BaCeO3-based HTPC. BaCe0.8SmxY0.2–xO3−δ (0 ≤ x ≤ 0.2) powders are synthesized by a typical citrate–nitrate combustion method. The XRD and Raman spectra reveal all the compounds have an orthorhombic perovskite structure. The effects of Sm and/or Y doping on the sinterability and electrical conductivity under different atmospheres are carefully investigated. The SEM results of the sintered BaCe0.8SmxY0.2–xO3−δ pellets indicate a significant sintering enhancement with increasing Sm concentration. BaCe0.8Sm0.1Y0.1O3−δ exhibits the highest electrical conductivity in hydrogen among the BaCe0.8SmxY0.2–xO3−δ pellets. Anode-supported BaCe0.8Sm0.1Y0.1O3−δ electrolyte membranes are also fabricated via a drop-coating process, and the corresponding single cell exhibits desirable power performance and durability at low temperatures. The results demonstrate that BaCe0.8Sm0.1Y0.1O3−δ is a promising proton conductor with high conductivity and sufficient sinterability for proton-conducting solid oxide fuel cells operating at reduced temperatures.Keywords: barium cerate; electrical conductivity; high temperature proton conductors; sinterability; solid oxide fuel cells;

•Chemically stable BaZr0.8Y0.2O3−δ–Ni was successfully demonstrated as an anode for a highly efficient Ce0.8Sm0.2O2−δ-based SOFC.•A thin electron-blocking layer composed of Ce0.8Sm0.2O2−δ@Ba(Ce, Zr)1−x(Sm, Y)xO3−δ core/shell-like grains was formed in situ at the anode/electrolyte interface.•The electron-blocking layer substantially eliminated electronic conduction through electrolyte film.•The new structured cell output high open circuit voltages, promising power densities as well as good operating durability.Chemically stable composite BaZr0.8Y0.2O3−δ–Ni (BZY–Ni) was proposed and evaluated as the anode for solid oxide fuel cells (SOFCs) based on Ce0.8Sm0.2O2−δ (SDC) electrolyte. A thin electron-blocking interlayer was formed in situ at the anode/electrolyte interface when the anode-supported half cell was prepared via a high-temperature sintering process. Raman spectra and high-resolution TEM (HRTEM) results revealed that the electron-blocking interlayer consisted of Ce0.8Sm0.2O2−δ@Ba(Ce, Zr)1−x(Sm, Y)xO3−δ core/shell-like grains. The Ba(Ce, Zr)1−x(Sm, Y)xO3−δ shell protected SDC grains from reduction and consequently the electronic conduction through the SDC electrolyte film was nearly completely eliminated in the new structured fuel cell. The fuel cell exhibited significantly improved open circuit voltages (OCVs), high power densities as well as good operating durability, demonstrating that BZY–Ni is a promising anode for CeO2-based SOFCs operating at a higher efficiency. These findings also imply that doped CeO2@doped Ba(Ce, Zr)O3 core/shell composite is a promising electrolyte with high ionic transport number, which directs a new strategy to design novel electrolyte materials for SOFCs.