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Symmetric solid oxide fuel cells (SSOFCs) have typically drawn interest because of their ability to boost the chemical and thermal stability between electrolytes and electrodes as well as to reduce the manufacturing cost. However, the poor catalytic activity of symmetrical electrodes at low temperatures restricts the development of high-performance SSOFCs. Herein, we employ a well-known Li-ion battery cathode Li(Ni1/3Co1/3Mn1/3)O2(LNCM) material to SOFCs as a symmetrical electrode that possesses excellent catalytic activity toward both the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR). In addition, the Schottky junction formed by reduced LNCM at the anode side with the electrolyte eliminates the possibility of electronic shorting circuit problem. Meanwhile, the formation of online Li2CO3 makes the electrolyte membrane fully dense by filling the pores. All factors were combined to show adequate performance by LNCM as symmetric electrode-based SOFCs. Our work successfully demonstrates the rational design of favourable lithium-ion cathode materials for symmetrical electrode applications in low-temperature SOFCs.

First-principles calculations are performed using density function theory to explore the effects of dopant Ca in ceria (Ce1-xCaxO2-δ). The impact of oxygen vacancy on band gap and density of states is examined in doped ceria using generalized gradient approximations. Vacancy association and vacancy formation energies of the doped ceria are calculated to reveal the effect of dopant on ion conduction. The experimental study of the sample (Ce0.875Ca0.125O2-δ) was performed to compare with the theoretical results. The obtained results from theoretical calculation and experimental techniques show that oxygen vacancy increases the volume, lattice constant (5.47315 A) but decrease the band gap (1.72 eV) and bulk modulus. The dopant radius (1.173 A) and lattice constant (5.4718 A) are also calculated by equations which is close to the DFT lattice parameter. The result shows that oxygen vacancy shifts the density of states to lower energy region. Band gap is decreased due to shifting of valence states to conduction band. Vacancy formation shows a significance increase in density of states near the Fermi level. Density of states at Fermi level is proportional to the conductivity, so an increase in density of states near the Fermi level increases the conductivity. The experimental measured ionic conductivity is found to 0.095 S cm−1 at 600 °C. The microstructural studies is also reported in this work.

© 2018 Elsevier Ltd and Techna Group S.r.l. Stable and compatible cathode materials are a key factor for realizing the low-temperature (LT, ≤600 °C) operation and practical implementations of solid oxide fuel cells (SOFCs). In this study, perovskite oxides SrFe 1-x Ti x O 3-δ (x < = 0.1), with various ratios of Ti doping, are prepared by a sol-gel method for cathode material for LT-SOFCs. The structure, morphology and thermo-gravimetric characteristics of the resultant SFT powders are investigated. It is found that the Ti is successfully doped into SrFeO 3-δ to form a single phase cubic perovskite structure and crystal structure of SFT shows better stability than SrFeO 3-δ . The dc electrical conductivity and electrochemical properties of SFT are measured and analysed by four-probe and electrochemical impedance spectra (EIS) measurements, respectively. The obtained SFT exhibits a very low polarization resistance (R p ),.01 Ωcm 2 at 600◦C. The SFT powders using as cathode in fuel cell devices, exhibit maximum power density of 551 mW cm −2 with open circuit voltage (OCV) of 1.15 V at 600◦C. The good performance of the SFT cathode indicates a high rate of oxygen diffusion through the material at cathode. By enabling operation at low temperatures, SFT cathodes may result in a practical implementation of SOFCs.

In this study we present a new nanocomposite electrolyte based on samarium (Sm) and germanium (Ge) co-doped ceria Ce 0.7 Sm 0.15 Ge 0.15 O 2-δ (SGeDC). The nanocomposite electrolyte was prepared using co-precipitation method. The crystal structure and surface morphology were determined using x-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Four probe dc conductivity indicated the value of 0.074 S/cm at 650 °C. The Fuel cell performance was carried out using hydrogen as fuel. The maximum OCV observed was 0.95 V while the peak power density came out to be 600 mW/cm 2 at 600 °C. It is suggested that adding Ge, the conductivity as well as performance of this new nanocomposite electrolyte is comparatively enhanced and it can find potential applications in low temperature solid oxide Fuel cells (LTSOFCs).