proton and oxide ion conductions exist, produce high current output for fuel cell operation and high hydrogen output for electrolysis operation. Zirconia doped with scandia and ceria (10Sc1CeSZ) is also investigated as potential electrolyte in SORFC for hydrogen production at intermediate temperatures(500-750 °C). It is reported that 10Sc1CeSZ shows good behavior and produces high current densities, with suitable electrodes. Current density–voltage ( j–V) curves and impedance spectra are investigated and recorded. Impedance spectra are realized applying an ac current of 1–2A RMS (root-mean-square) in the frequency range from 30 kHz to 10−1 Hz. Impedance spectra shows that the resistance is high at low frequencies(<10 kHz) and near zero at high frequencies(>10 kHz). Since high frequency corresponds to electrolyte activities, while low frequencies corresponds to electrodes process, it can be deduced that only a small fraction of the overall resistance is from the electrolyte and most resistance comes from anode and cathode. Hence, developing high performance electrodes are essential for high efficiency SORFC. Area specific resistance can be obtained from the slope of j-V curve. Commonly used/tested electrodes materials are nickel/zirconia cermet (Ni/YSZ) and lanthanum-substituted strontium titanate/ceria composite for SORFC cathode, and lanthanum strontium manganite (LSM) for SORFC anode. Other anode materials can be lanthanum strontium ferrite (LSF), lanthanum strontium copper ferrite and lanthanum strontium cobalt ferrite. Studies show that Ni/YSZ electrode was less active in reverse fuel cell operation than in fuel cell operation, and this can be attributed to a diffusion-limited process in the electrolysis direction, or its susceptibility to aging in a high-steam environment, primarily due to coarsening of nickel particles. Therefore, alternative materials such as the titanate/ceria composite (La0.35Sr0.65TiO3–Ce0.5La0.5O2−δ)or (La0.75Sr0.25)0.95Mn0.5Cr0.5O3 (LSCM) have been proposed electrolysis cathodes. Both LSF and LSM/YSZ are reported as good anode candidates for electrolysis mode. Furthermore, higher operation temperature and higher absolute humidity ratio can result in lower area specific resistance. See also Glossary of fuel cell terms Hydrogen technologies Flow Battery References External links 2005– PEM regenerative fuel cell energy storage system Data sheet Model Car with a reversible fuel cell(PDF) Compact Fuel Cell with Interleaved Electrolysis Layers Fuel cells