High Temperature Steam Electrolysis Research Articles

LSC Infiltrated LSCF Oxygen Electrode for High Temperature Steam Electrolysis

This work is focused on La0.6Sr0.4CoO3-δ (LSC) infiltrated LSCF oxygen electrode for high temperature steam electrolysis aimed at efficient hydrogen production. The electrochemical performance of LSC infiltrated LSCF oxygen electrode is investigated for steam electrolysis and compared with conventional LSCF electrode. In this respect, the symmetrical half-cell as well as single cell containing LSCF oxygen electrode with and without LSC infiltration are characterized using electrochemical impedance spectroscopy in the temperature range 750-900 °C. It is observed that the symmetrical cell as well as single cells with LSC infiltrated LSCF electrode performs slightly better than the conventional LSCF electrode. Degradation experiments were also performed for both symmetrical as well as single cells. Post-test analysis using SEM-EDX was performed to investigate the changes of electrode and electrode/electrolyte interface microstructures.

(Invited) Sr and Mn Doped LaFeO3 Perovskite Oxide As Active Cathode for High Temperature Electrolysis

Solid oxide electrolysis cells (SOECs) for converting CO2 to more useful chemical species are attracting considerable attention because of their high electrolytic efficiency, offering the possibility of direct conversion of CO2 to CO (CO2 → CO + 1/2O2). In addition, recently, high temperature electrolysis of steam to H2 is also attracing much interest. Heat energy supplied to SOECs can maximize electrolysis efficiency, offering both thermodynamic and kinetic advantages. The generated CO can be used as a fuel gas, converted into syngas via reaction with H2, or to reduce iron oxide to pure iron in the iron-making process. The application of SOECs and related technologies can contribute to a more sustainable economy. For the electrolyte in SOECs, ZrO2 doped with 8 mol% of Y2O3 (YSZ) has always been used because of its chemical stability and mechanical strength. However, an electrolyte for CO2 or H2O electrolysis with lower internal resistance and increased efficiency is highly desirable. LaGaO3-based electrolytes have higher oxide-ion conductivities and transport numbers, which can lead to higher energy conversion efficiency; hence, a doped-LaGaO3 electrolyte (La0.9Sr0.1Ga0.8Mg0.2O3, LSGM) has been tested in this study. For CO2 and H2O electrolysis, another drawbacks is durability since electrode is easily aggregated and deactivated. Although metals, particularly Ni, are widely used as cathodes in CO2 electrolysis cells, we found that a LaFeO3−δ-based perovskite cathode (La0.6Sr0.4Fe0.8Mn0.2O3−δ, LSFM6482) showed the highest activity for CO2 and H2O electrolysis among the examined oxides Among the cells using a La0.6Sr0.4Fe0.9M0.1O3−δ-based oxide cathode (M = Mn, Co, Ni, or Cu) for CO2 electrolysis at 1073K. Mn was the most effective Fe replacement on the B site, and the La0.6Sr0.4Fe0.9Mn0.1O3−δ cathode showed the highest activity and current density for CO2 electrolysis of this set of cathodes. Among the tested dopants, Mn and Co have ionic sizes most similar to Fe and a smaller size mismatch between the host and dopant cations in the perovskite structure, which should suppress dopant segregation and minimize detrimental effects of cation segregation. Overall, among the examined cations, Mn was the best dopant for the B site of the LaFeO3 cathode. A cell consisting of BLC64/LSGM/LSFM6482 exhibited the highest CO2 electrolysis activity (a current density of 0.52 A/cm2 at 1.6 V and 1173 K) of all cathodes investigated in this study and reduced CO2 at a rate of 153 μmol/cm2•min at 1173 K and 1.6 V with negligible carbon formation. In this study, change in internal resistance during electrolysis is also discussed based on impedance measurement.

High activity oxide Pr0.3Sr0.7Ti0.3Fe0.7O3−δ as cathode of SOEC for direct high-temperature steam electrolysis

A high activity ferrite Pr0.3Sr0.7Ti0.3Fe0.7O3−δ (PSTF) has been synthesized and examined as a cathode of solid oxide electrolysis cell (SOEC) for direct high-temperature steam electrolysis. The SOEC with a configuration of PSTF|YSZ|LSM-YSZ was operated under H2O concentrations ranging from 20%H2O/Ar to 60%H2O/Ar and exhibited excellent electrochemical performances. Polarization resistance of the electrolyzer was as small as 0.43 Ω cm2 in 60%H2O/Ar at 1.85 V at 800 °C. According to AC impendence spectra analyzing, gas diffusion process was the rate-determine-step (RDS) under smaller current density, while under larger current density, transport properties in the electrodes and the interfaces of electrode/electrolyte was RDS. The electrochemical properties of PSTF cathodes were systematically investigated and compared when they were exposed to gas atmosphere with and without safe gas (H2). The obtained results demonstrated that PSTF electrode could conceivably avoid any hydrogen feeding for steam electrolysis.

Exergy analyses of green hydrogen production methods from biogas-based electricity and sewage sludge

In this study, five models are considered for the use of biogas-based electricity and sewage sludge obtained from a municipal wastewater treatment plant for green hydrogen production. These models include alkaline, PEM, high temperature water electrolysis, alkaline hydrogen sulfide electrolysis and dark fermentation biohydrogen production processes. Energy and exergy analyses are performed on these models by applying thermodynamic procedures and the results are compared. The daily hydrogen production rates of the models are found as 594, 625.4, 868.6, 10.8 and 56.74 kg and the exergetic efficiencies of the models are calculated as 19.81, 20.66, 25.83, 24.86 and 60.54%, respectively. In terms of the exergetic efficiency, the dark fermentation biohydrogen production process is found to be superior to the other models, followed by the high temperature steam electrolysis process. This paper aims to determine the most appropriate model for a wastewater treatment plant among the considered models in terms of exergy efficiency.

Performance of Non‐Destructive Compressive Seals for Reversible Solid Oxide Cells

AbstractContrary to hardened glass ceramics, compressive non‐destructive seals for solid oxide cells (SOCs) could enable stack repairs without utilizing destructive separation methods. In light of increasing interest for high temperature steam electrolysis and energy storage, the performances of two commercially available compressive materials were investigated in humidified gas conditions: Thermiculite‐866 and AFS‐170 alumina felts. Mass loss and thermogravimetric (TGA) experiments carried out in inert, oxidizing, and reducing atmospheres at 800 °C showed no influence of the atmosphere on the alumina felts, and a reversible redox behavior for Thermiculite‐866. Thermiculite‐866 showed better cyclability compared to AFS‐170 during SOC thermal cycling experiments. Initial open circuit voltages in dry H2 were measured and compared to those obtained with commercial mica seals. The highest were recorded with Thermiculite‐866, followed by mica and AFS‐170. The species outgassed by Thermiculite‐866 were quantified, and fluorine was found to be the main component released at 800 °C.

Development and Demonstration of a Novel Reversible SOFC System for Utility and Micro Grid Energy Storage

AbstractEnergy storage is a critical component to supply local energy generation for both grid and off‐grid connected facilities and communities, enabling localized grid independent energy secure power in cases of emergencies or unreliable traditional grid use. The high cost and energy security of importing fuel to islanded grids has led to a growing need to generate power onsite with alternative and renewable energy technologies while reducing facility costs of importing electrical power. However, utility grid operators are being faced with the challenges of intermittent and variability in energy production from renewables. Therefore, energy storage is crucial to balance micro and utility grids, improve efficiency, reduce fuel consumption, and provide critical power in the event of power outages. There has been particular interest in reversible solid oxide fuel cells (RSOFCs) in the energy sector for electricity, energy storage, grid stabilization and improvement to power plant system efficiency due to favorable thermodynamic efficiencies of high temperature steam electrolysis. Boeing has been active in the development of a fully integrated, grid tied RSOFC system for micro grid and commercial utility energy storage using Sunfire fuel cell technology. In this system, excess grid energy or curtailed power generated by renewables is sent to the system operating in electrolysis mode to produce H2. The H2 is stored and then used in the system's fuel cell mode to provide supplemental power to the grid during peak hours or as needed. As part of this program, Boeing has developed a H2 storage and compression system, power distribution system, and master controller to interface with RSOFC subsystems. Sunfire developed a reversible solid oxide cell module with a power output of 50 kW in SOFC mode and 120 kW input in electrolysis mode producing 3.5 kg H2 hr−1. The system was demonstrated while connected to the local utility grid and operated in a microgrid test environment. This paper will discuss the development, integration, and demonstration of the RSOFC system.

Concurrent hydrogen and water production from brine water based on solar spectrum splitting: Process design and thermoeconomic analysis

This paper presents a novel process for high efficiency production of hydrogen and desalination of brine water based on the concept of solar spectrum splitting. The advantage of this system is concurrent production of hydrogen and distilled water using a sustainable process at large scale. The harvested energy from the separated solar spectral bands is used to supply the required energy for high temperature steam electrolysis and a double-stage flash distillation system. The integrated solar system is designed to reduce the energy conversion deficiencies, considerably. In order to investigate the performance of this system, a process simulation code is developed. An exergy analysis is conducted and the economic feasibility of the plant is evaluated. The sensitivity of the integrated cycle performance on solar insolation, electrolyzer temperature, and pressure is analyzed, and the results indicate that utilization of concentrator cells, with a multi-band gap mirror can increase the productivity of the cycle, drastically. It is observed that hydrogen and distilled water production rate can be increased by more than 1.6 times, when the harvested solar power increases from 28 MW to 55 MW. It is concluded that the maximum energy and exergy efficiencies of the integrated solar cycle is about 45%.

Symmetrical Solid Oxide Electrolyzer Cells (SOECs) with La0.6Sr0.4Co0.2Fe0.8O3 (LSCF)-Gadolinium Doped Ceria (GDC) Composite Electrodes

Scandia (Sc2O3)-stabilized zirconia (ScSZ) electrolyte-supported symmetrical solid oxide electrolyzer cells (SOECs), in which lanthanum strontium cobalt ferrite (LSCF)-gadolinia (Gd2O3)-doped ceria (GDC) composite materials are used as both the cathode and anode, were fabricated and their high temperature steam electrolysis (HTSE) performance was investigated. Current density-voltage curves were obtained for cells operated in 10% H2O/90% Ar at 750, 800, and 850ºC. It was possible to determine the ohmic, cathodic, and anodic contributions to the total overpotential using the three-electrode technique. The HTSE performance was significantly improved in the symmetrical cell with LSCF-GDC electrodes compared to the cell consisting of an Ni-YSZ cathode and LSCF-GDC anode. It was found that the overpotential due to the LSCF-GDC cathode largely decreased and, at a given current density, the total cell voltage decreased, which resulted in the enhanced hydrogen production rate in the symmetrical cell. Key words: HTSE, SOECs, Symmetrical cell, LSCF-GDC, Hydrogen production rate

An experimental investigation of fuel assisted electrolysis as a function of fuel and reactant utilization

In this paper we describe and analyze the results of experiments on a Solid Oxide Electrolyzer Cell with and without the supply of a fuel to the oxygen producing electrode. In the experiments a 5 × 5 cm2 Solid Oxide Fuel Cell is used operating in electrolyzer mode. We have tested the influence of varying reactant utilization (i.e. steam utilization) and fuel utilization in fuel assisted electrolysis. In particular the effect of insufficient fuel supply was studied experimentally as well as theoretically. In doing so we defined a turning point at which all the fuel is utilized. It was shown that by supplying not enough fuel all the fuel is oxidized and as in conventional electrolysis, oxygen production will start and oxygen is leaving the cell. Moreover the cell performance approaches conventional electrolysis and the effect of adding fuel on reducing the necessary amount of electric power almost vanishes. As in conventional high temperature steam electrolysis conversion efficiencies of more than hundred percent can be achieved also with fuel assisted electrolysis, under the condition that sufficient fuel is supplied i.e. fuel utilization must be lower than hundred percent.We have put the concept of fuel assisted electrolysis in the framework of multisource multiproduct energy systems (MSMP's) and emphasized for example the benefits of using bio(syn)gas as the fuel in fuel assisted electrolysis. When using bio(syn)gas, the gas is de facto upgraded to pure hydrogen. This is an additional benefit next to the lowering of the electric power consumption for producing the same amount of hydrogen in the fuel assisted electrolysis process. Furthermore the suitability of these flexible MSMP systems in a market with volatile electricity prices due to increasing penetration of intermittent renewable energy sources is highlighted.

Temperature and reactive current distributions in microtubular solid oxide electrolysis cells

A two-dimensional tubular model of a cathode supported microtubular solid oxide electrolysis cell (SOEC) was developed in order to investigate the temperature distribution within the cell during high-temperature steam electrolysis. High-temperature steam electrolysis using SOECs allows for highly efficient hydrogen generation, because the heat from the overpotential can be recycled in the form of a heat source for the electrolysis reaction. However, to improve the durability and strength of the components, an understanding of the temperature distribution of the cell is essential, because heat absorption during electrolysis reaction leads to complex temperature distributions. The current density–voltage curves obtained using the above-mentioned model were in good agreement with the experimental ones. The calculated and measured temperature distributions indicated that the distribution in microtubular SOECs is a nonuniform one and suggested that the current-collecting positions strongly affect the temperature and reaction distributions under the conditions used herein.

Performance Evaluation of Intermediate-Temperature Reversible Solid Oxide Fuel Cell at VPS

Hydrogen has been considered as a potential alternative fuel for future energy supplies and can be produced through high temperature steam electrolysis. The technology can be realized through reversible operation of solid oxide fuel cells (SOFCs), involving reduction of water at the cathode to form hydrogen and rejection of oxygen to air at the anode. Versa Power Systems (VPS) is a developer of SOFC technology focused on large stack and system development for commercial applications. In recent years VPS has been developing RSOFC material systems for the purpose of future commercial development of RSOFC stacks. VPS has demonstrated significant technical improvements in RSOFC materials technology including demonstrated cell operation up to 6 A/cm2 with <1.67 V operating voltage at 800°C. Recent work has focussed on the effects of testing conditions on cell durability using performance testing (polarisation) and electrochemical impedance spectroscopy.

Energy and exergy analyses of integrated hydrogen production system using high temperature steam electrolysis

In this study, thermodynamic performance assessment of solar-driven integrated HTSE for hydrogen production is discussed in detail. The system consists of a solar tower, Brayton cycle, Rankine cycle, organic Rankine cycle (ORC) and high temperature steam electrolysis (HTSE). The required heat energy for power generation cycles are supplied from solar energy while produced electricity is used for the necessary energy demand of HTSE. For the analyses, the inlet and outlet energy and exergy rates of all subsystems are calculated and illustrated accordingly. From the results of the analyses, the overall energy and exergy efficiencies of the considered system are found to be 24.79% and 22.36% for power generation section and 87% and 88% for hydrogen production section respectively. Also it is found that without any auxiliary equipment, the considered hydrogen production process consumes 1.98 kWhe at 230 °C, generates 0.057 kg/s H2.

Ce0.6Mn0.3Fe0.1O2-δ as an Alternative Cathode Material for High Temperature Steam Electrolysis Using LaGaO3-based Oxide Electrolyte

Ce0.6Mn0.3Fe0.1O2-δ (CMF) has been used as a new oxide cathode of solid oxide electrolysis cell (SOEC) using LaGaO3-based electrolyte for H2 production under a feeding gas composition of 20%steam/1%H2/79%Ar. CMF cathode exhibits good electrolysis performance and well-performed hydrogen production rate with the Faraday’s law at 1173-973K. Through impedance measurement under a DC polarized condition, the studies show that polarization resistance and ohmic resistance decreased with increasing DC bias potential. Furthermore, CMF showed good stability, and no significant aggregation and delamination were noticed during the electrolysis measurement. These results suggest that CMF can be a promising oxide cathode candidate for intermediate temperature SOEC.

Numerical simulation of steam electrolysis with a solid oxide cell for proper evaluation of cell performances

A quasi-1D simulation model was developed to estimate total area-specific resistance for overvoltages (Rtot) and cell voltage by separating gas conversion impedance (GCI) from overall real-part impedance in high temperature steam electrolysis with a solid oxide cell (SOEC). GCI and Rtot for a square cell was estimated as 0.012–0.011 Ω cm2 and 0.206–0.216 Ω cm2, respectively, at J = 0.0–1.8 A cm−2, 800 °C, and relatively high flow rates. Even though GCI is small compared to Rtot, ignoring the GCI will result in higher simulation errors at J > 0.5 A cm−2. Simulation results attained ±0.3% or better precision against measured cell voltages at 750–850 °C. Furthermore, case studies at 800 °C revealed ±40% local current density distribution in the cell at 1.0 A cm−2 and 82% steam utilization. GCI was roughly inversely proportional to gas flow-rates and depended on steam utilization. Improvement of Rtot to 0.150 Ω cm2 could attain more than 1.75 A cm−2 at 1.30 V.

Progress of the IAHE Nuclear Hydrogen Division on international hydrogen production programs

This paper presents recent activities of the IAHE Nuclear Hydrogen Division and associated research advances in Canada, China, France, Germany, Poland, and Romania on programs and major initiatives on large-scale hydrogen production and utilization. Germany and France have made significant advances in high temperature steam electrolysis (HTSE). Germany is going to demonstrate a 3-kW steam electrolyzer and 100-kW Hybrid Sulfur Cycle powered by solar energy soon. France operated several HTSE 25-cell stacks at various operating points. Recently, a HTSE packaged system has been built, containing this 25-cell stack and other Balance of Plant components. At 700 °C, this system produces 1.2 Nm3/h of H2 with a total electrical consumption of 3.9 kWh/Nm3, achieving 92% of efficiency (electrical consumption of the system vs HHV of the produced hydrogen). It demonstrates that a 150 °C heat source temperature is sufficient for the steam generation, and that a slightly exothermic operating mode of the stack is sufficient to preheat the inlet gas up to 700 °C and compensate the heat losses of the system. China has also made significant progress in developing the HTSE process at a hydrogen production rate of 105 dm3/h and the thermochemical Sulfur–Iodine (SI) cycle at the rate of 60 dm3/h, which already achieved the goal of China's HTR-PM Demonstration Nuclear Power Plant Project. The components and facilities were developed and tested in Tsinghua University. Romania is collaborating with Canada on nuclear hydrogen production with the thermochemical Cu–Cl cycle. The individual unit operations of the Cu–Cl cycle have been verified experimentally. Research on integration of a laboratory scale system to produce 3 kg of hydrogen per day is underway at the University of Ontario Institute of Technology in Oshawa, Ontario. Poland has developed advanced simulation capabilities for Solid Oxide Fuel/Electrolysis Cells for hydrogen peak energy storage as well as laboratory scale experiments focused on solid oxide and molten carbonate fuel cells. This paper presents a review of activities of members of the IAHE Nuclear Hydrogen Division in these six countries.

Temperature Distribution Responses of a Micro-Tubular SOEC after an Electric Load Change

A two-dimensional tubular model of a nickel + yttria-stabilized zirconia electrode supported micro-tubular solid oxide electrolysis cell (SOEC) was developed in order to investigate the temperature distribution during high-temperature steam electrolysis. High-temperature steam electrolysis using SOECs allows for highly efficient hydrogen generation, because the heat from the overpotential can be recycled in the form of a heat source for the electrolysis reaction. In this paper, the numerical model was expanded to unsteady model, and the temperature distribution responses after electric load changes of 0.2 A/cm2 to 0.0 A/cm2, 0.4 A/cm2 to 0.0 A/cm2 and 0.6 A/cm2 to 0.0 A/cm2 were calculated.

High-performance solid oxide electrolysis cell based on ScSZ/GDC (scandia-stabilized zirconia/gadolinium-doped ceria) bi-layered electrolyte and LSCF (lanthanum strontium cobalt ferrite) oxygen electrode

The work presented focuses on the development and performance evaluation of Ni-YSZ (nickel-yttria-stabilized zirconia) supported solid oxide cell with bi-layered ScSZ/GDC electrolyte structure and LSCF (lanthanum strontium cobalt ferrite) oxygen electrode in high-temperature steam and carbon dioxide electrolysis. At 800 °C, the cell exhibited a very high electrolysis current density of about −2.2 A/cm2 and −1.9 A/cm2 in steam and CO2 electrolysis, respectively. A slightly lower ASR (area specific resistance) is observed in electrolysis mode when compared to fuel-cell mode. Moreover, the ASR is increased when increasing the CO2 concentration in both modes of operation. The OCV (open circuit voltage) of SOEC with bi-layered electrolyte structure is significantly improved than the cell with single-layered GDC (gadolinium-doped ceria) electrolyte but at the cost of an increase in the ohmic resistance (Rs) of cell. The formation of (Zr, Ce)O2−x solid solution by the mutual diffusion of zirconium and cerium during co-sintering is found to be the origin of the increase in the Rs. Impedance spectra revealed that the high electrolysis performance is caused by the low polarization losses at LSCF oxygen electrode rather than the thin bi-layered ScSZ/GDC electrolyte structure.

Influence of pressure on solid oxide electrolysis cells investigated by experimental and modeling approach

For many industrial applications, hydrogen must be pressurized before being used or stored. Because compressing liquid water is less energetic than the first levels of gaseous H2 compression, High Temperature Steam Electrolysis (HTSE) performed under pressure might represent an advantageous way for hydrogen production. With the goal of improving the electrolysis efficiency, an experimental and modeling approach has been adopted in order to better understand the basic underlying mechanisms of pressurized electrolysis operation. Experiments were carried on two different single commercial solid oxide cells at 800 °C in the pressure range of 1–10 bar. As a first result, according to the i–V curves, two main pressure effects have been observed. First, as expected, the Open Circuit Voltage is higher under pressure. Then, the limiting current density is increased with increasing the pressure, meaning that the hydrogen production can be improved. The electrochemical model, which has been adjusted on the experimental i–V curves obtained at atmospheric conditions, has been validated for the pressurized operation. Simulations have shown that the improvement of the limiting current is related to the decrease of cathode's concentration overpotential with pressure. Moreover, an optimal pressure can be defined depending on the cell polarization. Higher pressures than the optimal one lead to slightly decrease the hydrogen production rate, mainly due to Open Circuit Voltage increase that cannot be balanced enough by the cathode's concentration overpotential decrease. Finally, this study demonstrates that cell performances under pressure are less sensitive to the variation of cermet-support microstructural properties.

Experimental design, operation, and results of a 4 kW high temperature steam electrolysis experiment

High temperature steam electrolysis (HTSE) is a promising technology for large-scale hydrogen production. However, research on HTSE performance above the kW level is limited. This paper presents the results of 4 kW HTSE long-term test completed in a multi-kW test facility recently developed at the Idaho National Laboratory (INL). The 4 kW HTSE unit consisted of two solid oxide electrolysis stacks electrically connected in parallel, each of which included 40 electrode-supported planar cells. A current density of 0.41 A cm−2 was used for the long-term operating at a constant current mode, resulting in a theoretical hydrogen production rate about 23 slpm. A demonstration of 830 h stable operation was achieved with a degradation rate of 3.1% per 1000 h. The paper also includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. This successful demonstration of multi-kW scale HTSE unit will help to advance the technology toward near-term commercialization.

Reversible Type Solid Oxide Fuel Cells Using Ni-Fe-CeO2 Based Cermet Fuel Electrode and Applied for Metal-Air Rechargeable Battery

Solid Oxide Fuel Cells (SOFC) is expecting as a highly efficient energy convertor. On the other hand, recently, there are strong interests on high temperature steam electrolysis because of efficient hydrogen production method. In addition, reversible operation of SOFCs is also interesting as an energy storage method. Therefore, recently, there is also high interest on reversible operation type SOFC so-called SORC. At present, for SORC, similar materials for conventional SOFC are widely used, i.e., Y2O3 stabilized ZrO2 and Ni based cermet for electrolyte and fuel electrode, respectively. However, because of high temperature operation, energy efficiency as well as stability is still not high as an energy storage process. In this study, we investigated intermediate temperature SORC using LaGaO3 electrolyte. For reversible type operation, aggregation of Ni is easily occurred but it was found that addition of small amount of Fe is effective for preventing aggregation of Ni. The optimized composition for fuel electrode is Ni-Fe(9:1) from stability. Effects of mixed conducting oxide added for Ni-Fe were studied. For SOFC operation, power density is larger as the following order, Ce(Mn,Fe)O2<NiFe=La(Sr)Ga(Mg)O 3<Ce0.8Sm0.2O2< La(Sr)Fe(Mn)O3. On the other hand, for SOFC operation, the electrolysis current density is increased as the following order, Ce(Mn,Fe)O2<NiFe<La(Sr)Ga(Mg)O3<< La(Sr)Fe(Mn)O3 <Ce0.8Sm0.2O2. Therefore, for reversible operation, NiFe-SDC shows the most active. Degradation of the cell using NiFe-SDC and Sm(Sr)CoO3 for fuel and air electrode, respectively, was studied at 1073 K, 100mA/cm2. The observed terminal potential was 1.13 and 1.025 V for SOEC and SOFC respectively at initial cycle and the observed potential slightly increased for SOFC and decreased for SOEC with cycle number, however, after 50 cycles, the observed terminal potential was 1.15 and 1.0 V for SOFC and SOFC, respectively. Therefore, the degradation is hardly observed for the reversible operation of the cell. Combination of SORC with metal oxidation could open a new application area for fuel cell. In this study, application of various metals like Fe, Sn, Al, and Mg to SORC were studied by using CaO Stabilized ZrO2 for electrolyte and it became clear that redox of metal proceeded in SORC electrochemically resulting in the all solid state metal-air rechargeable battery. The observed open circuit potential is well agreed with theoretical PO2 from Gibbs free energy of metal oxidation. By decreasing operating temperature, PO2 range of electrolyte domain can be expanded. Application of LSGM for electrolyte of this new concept of oxygen redox shuttle battery will also be discussed.