High-performance anode-supported solid oxide fuel cells with co-fired Sm0.2Ce0.8O2-δ/La0.8Sr0.2Ga0.8Mg0.2O3−δ/Sm0.2Ce0.8O2-δ sandwiched electrolyte

In this study, intermediate-temperature solid oxide fuel cells (IT-SOFCs) with a nine-layer structure are constructed via a simple method based on the cost-effective tape casting-screen printing-co-firing process with the structure composed of a NiO-based four-layer anode, a Sm_0.2Ce_0·8O_2-δ(SDC)/La_0·8Sr_0.2Ga_0.8Mg_0·2O_3?δ (LSGM)/SDC tri-layer electrolyte, and an La_0·6Sr_0·4Co_0·2Fe_0·8O_3-δ (LSCF)-based bi-layer cathode. The resultant SDC (4.14 μm)/LSGM (1.47 μm)/SDC (4.14 μm) tri-layer electrolyte exhibits good continuity and a highly dense structure. The R_o and R_p values of the single cell are observed to be 0.15 and 0.08 Ω cm² at 800 °C, respectively, and the MPD of the cell is 1.08 Wcm-2. The high MPD of the cell appears to be associate with the significantly lower area-specific resistance and the reasonably high OCV. Compared to those with a similar electrolyte thickness reported in prior studies, the nine-layer anode-supported IT-SOFC with a tri-layer electrolyte developed by the study demonstrates superior cell properties.     

La0.1SrxCa0.9−xMnO3−δ-Sm0.2Ce0.8O1.9 composite material for novel low temperature solid oxide fuel cells

Lowering the operating temperature of the solid oxide fuel cells (SOFCs) is one of the world R&D tendencies. Exploring novel electrolytes possessing high ionic conductivity at low temperature becomes extremely important with the increasing demands of the energy conversion technologies. In this work, perovskite La_0.1Sr_xCa_0.9?xMnO_3?δ (LSCM) materials were synthesized and composited with the ionic conductor Sm_0.2Ce_0.8O_1.9 (SDC). The LSCM–SDC composite was sandwiched between two nickel foams coated with semiconductor Ni_0.8Co_0.15Al_0.05LiO_2?δ (NCAL) to form the fuel cell device. The strontium content in the LSCM and the ratios of LSCM to SDC in the LSCM-SDC composite have significant effects on the electrical properties and fuel cell performances. The best performance has been achieved from LSCM-SDC composite with a weight ratio of 2:3. The fuel cells showed OCV over 1.0 V and excellent maximum output power density of 800 mW cm^?2 at 550 °C. Device processes and ionic transport processes were also discussed.     

Novel doped barium cerate–carbonate composite electrolyte material for low temperature solid oxide fuel cells

A composite of a perovskite oxide proton conductor (BaCe_0.7Zr_0.1Y_0.2O_3−δ, BCZ10Y20) and alkali carbonates (2Li₂CO₃:1Na₂CO₃, LNC) is investigated with respect to its morphology, conductivity and fuel cell performance. The morphology shows that the presence of carbonate phase improves the densification of oxide matrix. The conductivity is measured by AC impedance in air, nitrogen, wet nitrogen, hydrogen, and wet hydrogen, respectively. A sharp increase of the conductivity at certain temperature is seen, which relates to the superionic phase transition at the interface phases between oxide and carbonates. Single cell with the composite electrolyte is fabricated by dry-pressing technique, using nickel oxide as anode and lithiated nickel oxide as cathode, respectively. The cell shows a maximum power density of 957 mW cm⁻² at 600 °C with hydrogen as the fuel and oxygen as the oxidant. The remarkable proton conductivity and excellent cell performance make this kind of composite material a good candidate electrolyte for low temperature solid oxide fuel cells (SOFCs).     

High-performance NdSrCo2O5+δ–Ce0.8Gd0.2O2-δ composite cathodes for electrolyte-supported microtubular solid oxide fuel cells

NdSrCo₂O_5+δ (NSCO) is a perovskite with an electrical conductivity of 1551.3 S cm⁻¹ at 500 °C and 921.7 S cm⁻¹ at 800 °C and has a metal-like temperature dependence. This perovskite is used as the cathode material for Ce_0.8Gd_0.2O_2-δ (GDC)-supported microtubular solid oxide fuel cells (MT-SOFCs). The MT-SOFCs fabricated in this study consist of a bilayer anode, comprising a NiO–GDC composite layer and a NiO layer, and a NSCO–GDC composite cathode. Three cell designs with different outer tube diameters, GDC thicknesses, and NSCO/GDC ratios are designed. The MT-SOFC with an outer tube diameter of 1.86 mm, an electrolyte thickness of 180 μm, and a 5NSCO–5GDC composite cathode presents the best performance. The flexural strength of the aforementioned cell is 177 MPa, which is sufficient to confer mechanical integrity to the cell. Moreover, the ohmic and polarization resistance values of the cell are 0.22 and 0.09 Ω cm² at 700 °C, respectively, and 0.15 and 0.03 Ω cm² at 800 °C, respectively. These results indicate that the NSCO-GDC composite exhibits high electrochemical activity. The maximum power densities of the cell at 700 and 800 °C are 0.46 and 0.67 W cm⁻², respectively, exceeding those of existing electrolyte-supported MT-SOFCs with similar electrolyte thicknesses.     

Validating the efficiency of γ-Al2O3/La0.6Sr0.4Co0.2Fe0.8O3-δ double-layer electrolyte for low temperature solid oxide fuel cell

Perovskite La_0.6Sr_0.4Co_0.2Fe_0.8O_3+δ (LSCF) as a promising cathode material possessed overwhelming electronic conduction along with certain ionic conductivity. Its strong electron conduction capability hinder the application of pure-phase LSCF as electrolyte in semiconductor membrane fuel cell (SMFC). In order to constrain the electron transport and take advantage of the decent ion conduction of LSCF, a thin layer of γ-Al₂O₃ with insulating property was added as an electron barrier layer and combine with LSCF to form a two-layer structure electrolyte. Through adjusting the weight ratio of LSCF/γ-Al₂O₃ to optimize the thickness of double layers, an open circuit voltage of 0.98 V and a maximum power density of 690 mW/cm² was received at 550 °C. At the same time, SEM, EIS and other characterization technology had proven that the LSCF/γ-Al₂O₃ bi-layer electrolyte can work efficiently at low temperature. The advantage of this work is the application of double-layer (γ-Al₂O₃/LSCF) structure electrolyte to instead of mixed material electrolyte in low-temperature solid oxide fuel cells. Structural innovation and the using of insulating materials provided clues for the further development of SMFC.     

Study on durability of novel core-shell-structured La0.8Sr0.2Co0.2Fe0.8O3-δ@Gd0.2Ce0.8O1.9 composite materials for solid oxide fuel cell cathodes

Core-shell-structured La_0.8Sr_0.2Co_0.2Fe_0.8O_3-δ@Gd_0.2Ce_0.8O_1.9 (LSCF@GDC) composite materials are synthesized and sintered as the SOFC cathodes by screen-printing method. The durability of core-shell-structured LSCF@GDC composite cathodes are evaluated through constant current polarizations (CCP) process at 750 °C and the results indicate that the core-shell-structured LSCF@GDC composite cathode (nanorod, 0.6) possesses an excellent long-term stability. In addition, molecular dynamics (MD) model is developed and applied to simulate the interaction between LSCF and GDC particles. According to the simulation results, compressive stress is generated at the cathode-electrolyte interface by the coated GDC layer. Combining with the X-ray diffraction (XRD) refinement results, it's revealed that the lattice strains are introduced in LSCF lattices because of the compressive stress. Furthermore, XPS results show that the core-shell-structured LSCF@GDC composite cathode (nanorod, 0.6) possess a better inhibition ability for Sr surface segregation. This study provides a possible way to suppress Sr surface segregation.     

Processing and characterization of novel Ce0.8Sm0.1Bi0.1O2-δ-BaCe0.8Sm0.1Bi0.1O3-δ (BiSDC-BCSBi) composite electrolytes for intermediate-temperature solid oxide fuel cells

Ce_0.8Sm_0.1Bi_0.1O_2-δ-BaCe_0.8Sm_0.1Bi_0.1O_3-δ (BiSDC-BCSBi) composites are fabricated as novel electrolytes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Both dramatically enhanced sinterability and electrical performance are obtained due to the Bi doping. BiSDC-BCSBi composites are densified at as low as 1200 °C, allowing a decrease of 350 °C compared with Ce_0.8Sm_0.2O_2-δ-BaCe_0.8Sm_0.2O_3-δ (SDC-BCS) composites. The optimal electrical conductivity of BiSDC-BCSBi electrolytes measured at 600 °C in humid air reaches up to 27.97 mS cm^?1, almost 6 times higher than that of SDC-BCS electrolytes (3.91 mS cm^?1 in humid air), which is mainly attributed to their lower sintering temperature, more uniform microstructure, larger tensile strains, and higher concentrations of O–H groups and oxygen vacancies. The electrolyte-supported single cell with BiSDC-BCSBi electrolyte displays a peak power density of 397 mW cm^?2 at 600 °C using humid hydrogen as fuel and ambient air as oxidant. These results imply that BiSDC-BCSBi composites have a great application prospect for IT-SOFCs.     

Stable SrCo0.7Fe0.2Zr0.1O3-δ cathode material for proton conducting solid oxide fuel cell reactors

SrCo_0.7Fe_0.2Zr_0.1O_3-δ (SCFZ) perovskite is prepared using a combustion method. SCFZ exhibits high stability while SrCo_0.8Fe_0.2O_3-δ without Zr doping decomposes in CO₂ and H₂O- containing atmosphere at elevated temperature. SCFZ also displays excellent chemical compatibility with BaCe_0.7Y_0.2Zr_0.1O_3-δ (BCYZ) proton conductor. A ceramic membrane fuel cell reactor is assembled with SCFZ + BCYZ composite cathode, porous Pt anode and BCYZ electrolyte. High selective ethylene and electrical energy are co-generated from ethane in the proton conducting solid oxide fuel cell reactor.     

Single layer low-temperature SOFC based on Ce0.8Sm0.2O2-δ- La0.25Sr0.75Ti1O3-δ-Ni0.8Co0.15Al0.05LiO2-δ composite material

This study reports a kind of single layer solid oxide fuel cell (SLSOFC) based on semiconductor-ionic conductor composite material which consists of Ce_0.8Sm_0.2O_2-δ (SDC, ionic conductor), La_0.25Sr_0.75Ti₁O_3+δ (LST, n-type semiconductor) and Ni_0.8Co_0.15Al_0.05LiO_2-δ (NCAL, p-type semiconductor). It was found that the LST-SDC-NCAL composite based SLSOFC exhibited open circuit voltage (OCV) of more than 1 V and maximum power density of 222 mW cm^?2 under 550 °C. In-situ Schottky junction in the device helps to prevent short circuiting as well as promote ion transport. Electrochemical impedance spectroscopy (EIS) analysis revealed that the ionic conductivity of the SLSOFC was about 0.09 S cm^?1, and the corresponding activation energy is 0.7 eV. The cell performance was stable during 65 h without any significant degradation. Moreover, the SLSOFC possessed higher tolerance for temperature change than traditional three-layer SOFC due to the well match of thermal expansion coefficient between electrodes and electrolyte. This device is of great significance in preventing fuel cell delamination, simplifying manufacturing process and promoting its commercialization.     

Stability considerations of semiconductor ionic fuel cells from a LNCA (LiNi0.8Co0.15Al0.05O2-δ) and Sm-doped ceria (SDC; Ce0.8Sm0.2O2-δ) composite electrolyte

Recent advances in composite materials, especially semiconductor materials incorporating ionic conductor materials, have led to significant improvements in the performance of low-temperature fuel cells. In this paper, we present a semiconductor LNCA (LiNi_0.8Co_0.15Al_0.05O_2-δ) which is often used as electrode material and ionic Sm-doped ceria (SDC; Ce_0.8Sm_0.2O_2-δ) composite electrolyte, sandwiched between LNCA thin-layer electrodes in a configuration of Ni-LNCA/SDC-LNCA/LNCA-Ni. The incorporation of the semiconductor LNCA into the SDC electrolyte with optimized weight ratios resulted in a significant power improvement, from 345 mW cm^?2 with a pure SDC electrolyte to 995 mW cm^?2 with the ionic-semiconductor SDC-LNCA one where the corresponding ionic conductivity reaches 0.255 S cm^?1 at 550 °C. Interestingly, the coexistence of ionic and electron conduction in the SDC-LNCA membrane displayed not any electronic short-circuiting but enhanced the device power outputs. This study demonstrates a new fuel cell working principle and simplifies technologies of applying functional ionic-semiconductor membranes and symmetrical electrodes to replace conventional electrolyte and electrochemical technologies for a new generation of fuel cells, different from the conventional complex anode, electrolyte, and cathode configuration.     

Exploring MnCr2O4–Gd0.1Ce0.9O2-δ as a composite electrode material for solid oxide fuel cell

Symmetrical solid oxide fuel cell (SOFC) adopting the same material at both electrodes is potentially capable of promoting thermomechanical compatibility between near components and lowering stack costs. In this paper, MnCr₂O₄–Gd_0.1Ce_0.9O_2-δ (MCO-GDC) composite electrodes prepared by co-infiltration method for symmetrical electrolyte supported and anode supported solid oxide fuel cells are evaluated at a temperature range of 650–800 °C in wet (3% H₂O) hydrogen and air atmospheres. Without any alkaline earth elements and cobalt, the co-infiltrated MCO-GDC composite electrode shows excellent activity for oxygen reduction reaction but mediocre activity for hydrogen oxidation reaction. With MCO-GDC as the cathode, the Ni-YSZ (Y₂O₃ stabilized ZrO₂) anode supported asymmetrical cell demonstrates a peak power density of 665 mW cm⁻² at 800 °C. The above results suggest MCO-GDC is a promising candidate cathode material for solid oxide fuel cells.     

The semiconductor SrFe0.2Ti0.8O3-δ-ZnO heterostructure electrolyte fuel cells

Highly ion-conducting properties in heterostructure composites and semiconductors have drawn significant attention in recent years for developing new electrolytes in low-temperature solid oxide fuel cells (LT-SOFCs). In this work, a new semiconductor heterostructure composite SrFe_0.2Ti_0.8O_3-δ (SFT)-ZnO consisting of p-type SFT and n-type ZnO is proposed and evaluated as an electrolyte in LT-SOFCs. Electrochemical studies reveal that the prepared SFT-ZnO is a mixed ion-electron conductor possessing a high ionic conductivity of 0.21 S cm⁻¹ at 520 °C and the assembled SFT-ZnO fuel cell can achieve a favorable peak power output of 650 mW cm⁻² along with high open-circuit voltage (OCV) of 1.06 V at 520 °C. By referring the semiconductor conduction types and energy band parameters of SFT and ZnO, a p-n bulk-heterojunction effect is proposed to describe the electronic blocking and ionic promotion processes of SFT-ZnO electrolyte in a fuel cell. Our work suggests a new insight into the design of effective LT-SOFC electrolytes by using semiconductor heterostructure material.     

Ba0.5Sr0.5Fe0.8Sb0.2O3-δ- Sm0.2Ce0.8O2-δ bulk heterostructure composite: A cobalt free Oxygen Reduction Electrocatalyst for low-temperature SOFCs

Low-temperature operated ceramic fuel cells (LT-CFCs 350° to 550 °C) hold a great promise than high-temperature solid oxide fuel cells (HT-SOFCs ≥ 800 °C) for numerous large-scale real-application. If a suitable cathode should be developed to overcome the sluggish oxygen reduction activity at low temperatures, the low-temperature operation of ceramic fuel cells could be possible. In this study, we have developed a cobalt-free Ba_0.5Sr_0.5Fe_0.8Sb_0.2O_3-δ- Sm_0.2Ce_0.8O_2-δ (BSFSb- SDC) a bulk heterostructure composite for efficient ORR electrocatalyst for LT-SOFC cathode. The established BSFSb-SDC bulk heterostructure composite exhibits large lattice parameters, very low-area-specific resistance, and high oxygen reduction reaction (ORR) activity at low operating temperatures. The prepared fuel cell device has demonstrated high-power densities of 890 mW-cm-² at 550 °C for button-sized SOFC on H₂ and even possible operation at 400 °C. It is also found that BSFSb-SDC effectively facilitates small polaron hopping of valence electrons and diffusion of oxygen ions. Various spectroscopic measurements such as X-ray photoelectron, UV–visible, Raman, and Density Functional Theory (DFT) calculations were employed to understand the improved ORR electrocatalyst function of BSFSb-SDC bulk heterostructure composite SOFC cathode. The results can further help to develop functional cobalt-free electro-catalysts for LT-SOFCs and other related applications.     

Modifying the cathodes of intermediate-temperature solid oxide fuel cells with a Ce0.8Sm0.2O2 sol–gel coating

To increase the performance of solid oxide fuel cells operated at intermediate temperatures (<700 °C), we used the electronic conductor La_0.8Sr_0.2MnO₃ (LSM) and the mixed conductor La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) to modify the cathode in the electrode microstructure. For both cathode materials, we employed a Sm_0.2Ce_0.8O₂ (SDC) buffer layer as a diffusion barrier on the yttria-stabilized zirconia (YSZ) electrolyte to prevent the interlayer formation of SrZrO₃ and La₂Zr₂O₇, which have a poor ionic conductivity. These interfacial reaction products were formed only minimally at the electrolyte–cathode interlayer after sintering the SDC layer at high temperature; in addition, the degree of cathode polarization also decreased. Moreover to extend the triple phase boundary and improve cell performance at intermediate temperatures, we used sol–gel methods to coat an SDC layer on the cathode pore walls. The cathode resistance of the LSCF cathode cell featuring SDC modification reached as low as 0.11 Ω cm² in air when measured at 700 °C. The maximum power densities of the cells featuring the modified LSCF and LSM cathodes were 369 and 271 mW/cm², respectively, when using O₂ as the oxidant and H₂ as the fuel.     

An ionic conductor Ce0.8Sm0.2O2−δ (SDC) and semiconductor Sm0.5Sr0.5CoO3 (SSC) composite for high performance electrolyte-free fuel cell

An advanced electrolyte-free fuel cell (EFFC) was developed. In the EFFC, a composite layer made from a mixture of ionic conductor (Ce_0.8Sm_0.2O_2?δ, SDC) and semiconductor (Sm_0.5Sr_0.5CoO₃, SSC) was adopted to replace the electrolyte layer. The crystal structure, morphology and electrical properties of the composite were characterized by X-ray diffraction analysis (XRD), scanning electron microscope (SEM), and electrochemical impedance spectrum (EIS). Various ratios of SDC to SSC in the composite were modulated to achieve balanced ionic and electronic conductivities and good fuel cell performances. Fuel cell with an optimum ratio of 3SDC:2SSC (wt.%) reached the maximum power density of 741 mW cm^?2 at 550 °C. The results have illuminated that the SDC-SCC layer, similar to a conventional cathode, can replace the electrolyte to make the EFFC functions when the ionic and electronic conductivities were balanced.     

Nanocomposite BaZr0.7Sm0.1Y0.2O3−δ–La0.8Sr0.2Co0.2Fe0.8O3−δ materials for single layer fuel cell

Single layer fuel cell (SLFC) is a novel breakthrough in energy conversion technology. This study is to realize the physical-electrochemical co-driving mechanism of a single component device composed of mixed ionic and semiconductor material. This paper is focused on investigating the mechanism and characterization of synthesized nanocomposite BaZr_0.7Sm_0.1Y_0.2O_3?δ (BZSY)–La_0.8Sr_0.2Co_0.2Fe_0.8O_3?δ (LSCF) in proportion 1:1 and 3:7 for SLFC. The crystallographic structure and morphology is studied with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The nano-particles lie in the range of 100–210 nm. Ultraviolet (UV) and electrochemical impedance spectroscopy (EIS) is used to analyze the semiconducting nature of nanocomposite (BZSY–LSCF). The performance of SLFC was carried out at different temperatures ranging between 400 and 650 °C. The mixed conductivity of the synthesized material was about 2.3 S cm^?1. The synergic effect of junction and energy band gap towards charge separation as well as the promotion of ion transport by junction built in field contributes to the working principle and high power output in the SLFC.     

High-performance solid oxide fuel cell based on iron and tantalum co-doped BaCoO3-δ perovskite-type cathode and BaZr0.1Ce0.7Y0.1Yb0.1O3-δ electrolyte

Proton conducting solid oxide fuel cells (H–SOFCs) have attracted much interest for their various advantages. BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb) displays both good proton conductivity and stability among all of the barium zirconate-cerate oxides such as BaZr_0.1Ce_0.7Y_0.2O_3-δ (BZCY) with proton conducting. In this study, an Fe and Ta co-doped perovskite-type oxide with the composition of BaCo_0.7Fe_0.2Ta_0.1O_3-δ (BCFT) is synthesized by the solid state reaction (SSR) method and studied as a high-performance cathode for H–SOFCs operated between 650 and 800 °C. The BCFT is chemically compatible with BZCYYb electrolyte, even co-sintering at 1000 °C for 10 h. The activating energy (Ea) of electrical conductivity for the BCFT sample is only 0.038 eV. The BCFT demonstrates superior oxygen reduction reaction (ORR) kinetics than that of BaCo_0.7Fe_0.2Nb_0.1O_3-δ (BCFN), when the Nb is completely substituted by Ta. The Ea of the polarization resistance (Rp) for BCFT is 0.911 eV, which is 0.11 eV lower than that of BCFN. The peak power density (PPD) of the anode-supported H–SOFC using BCFT is 1.65 W cm⁻² and the Rp is 0.01 Ω cm² at 800 °C. Therefore, the BCFT is a promising cathode for H–SOFCs based on BZCYYb electrolyte.     

Development of a PrBaMn2O5+δ-La0.8Sr0.2Ga0.85Mg0.15O3-δ composite electrode by scaffold infiltration for reversible solid oxide fuel cell applications

In this study, a PrBaMn₂O_5+δ (PBMO)-La_0.8Sr_0.2Ga_0.85Mg_0.15O_3-δ (LSGM) composite catalyst was developed for use in a reversible solid oxide fuel cell (SOFC) electrode. Through a chemical compatibility test, a heat treatment temperature at which secondary phases did not form between LSGM and PBMO was determined, and a PBMO-LSGM composite electrode material was synthesized by a scaffold infiltration technique capable of synthesizing a catalyst within the appropriate temperature range. A half-cell test consisting of two identical PBMO-LSGM composite electrodes supported on LSGM pellets found that the optimum infiltration amount of PBMO with respect to the LSGM scaffold was approximately 20 wt%. Electrochemical performance measurements under reversible SOFC operating conditions on a half-cell with 19.7 wt% PBMO-LSGM composite electrodes showed a specific resistance and activation energy significantly lower than those of conventional Ni-based cermet and perovskite-type materials, indicating that the developed PBMO-LSGM composite electrode is a promising electrocatalyst for reversible SOFCs.     

Investigation of Ce0.9Gd0.1O2-δ dispersed Sm1.5Sr0.5NiO4+δ: Cathode for intermediate temperature solid oxide fuel cell applications

Dispersion of nanocrystalline (94–350 nm) Ce_0.9Gd_0.1O_2-δ in superfine (260–312 nm) Sm_1.5Sr_0.5NiO_4+δ using modified precipitation technique is established using X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Presence of Ce_0.9Gd_0.1O_2-δ grains inhibits grain growth of Sm_1.5Sr_0.5NiO_4+δ, which provides morphological stability (up to 1100 °C). Ce_0.9Gd_0.1O_2-δ concentration dependent behaviours of ionic conductivity, surface exchange rate and electrode polarization resistance (R_p) of composites (determined using electrochemical impedance spectroscopy) are comprehended using percolation model. Three oxygen reduction reaction mechanisms are considered to understand electrochemical performance. Minimum R_p (0.81 Ω cm² at 700 °C) for 70Sm_1.5Sr_0.5NiO_4+δ:30Ce_0.9Gd_0.1O_2-δ is correlated to percolation threshold (optimum (i) electrochemically active sites (ii) oxygen reduction reaction kinetics, (iii) O^2- conductivity and (iv) charge transfer rate). Nano crystallite size of Ce_0.9Gd_0.1O_2-δ is crucial for enhancement in electrochemical performance. Oxygen partial pressure dependent electrochemical impedance spectroscopy studies reveal dominance of coexisting non-charge transfer oxygen adsorption/desorption and bulk O^2- diffusion.     

The electrolyte-layer free fuel cell using a semiconductor-ionic Sr2Fe1.5Mo0.5O6-δ – Ce0.8Sm0.2O2-δ composite functional membrane

Commercial double Perovskite Sr₂Fe_1.5Mo_0.5O_6-δ (SFM), a high performance and redox stable electrode material for solid oxide fuel cell (SOFC), has been used for the electrolyte (layer) -free fuel cell (EFFC) and also as the cathode for the electrolyte based SOFC in a comprehensive study. The EFFC with a homogeneous mixture of Ce_0.8Sm_0.2O_2-δ (SDC) and SFM achieved a higher power density (841 mW cm^?2) at 550 °C, while the SDC electrolyte based SOFC, using the SDC-SFM composite as cathode, just reached 326 mW cm^?2 at the same temperature. The crystal structure and the morphology of the SFM-SDC composite were characterized by X-ray diffraction analysis (XRD), and scanning electron microscope (SEM), respectively. The electrochemical impedance spectroscopy (EIS) results showed that the charge transfer resistance of EFFCs were much lower than that of the electrolyte-based SOFC. To illustrate the operating principle of EFFC, we also conducted the rectification characteristics test, which confirms the existence of a Schottky junction structure to avoid the internal electron short circuiting. This work demonstrated advantages of the semiconductor-ionic SDC-SFM material for advanced EFFCs.