Search Results (10)

Solid oxide fuel cells (SOFCs) are attracting attention as an eco-friendly power source because they show high power density. However, SOFC requires a high-temperature environment of 800 °C or higher, and accordingly, the problem of thermal stability of the material constituting SOFC has been raised. On the other hand, low-temperature solid oxide fuel cells (LT-SOFCs) research is steadily progressing to improve the electrochemical performance at low temperatures by improving the oxygen reduction reaction of the cathode by applying a cathode interlayer of various materials. In this study, LT-SOFCs were manufactured and electrochemically evaluated using praseodymium oxide (PrO_x) as a cathode interlayer. Scandium Stabilized Zirconia (ScSZ) pellets were used as electrolyte support for LT-SOFC, and PrO_x was deposited by various thicknesses as a cathode interlayer on ScSZ pellets by a sputtering process. Pt and Ni were deposited under the same process conditions for the cathode and anode, respectively. To analyze the thin-film characteristics of the PrO_x cathode interlayer, SEM (Scanning Electron Microscopy), X-ray Diffraction (XRD), and XPS (X-ray Photoelectron Spectroscopy) were analyzed. The electrochemical characteristics of LT-SOFCs were evaluated by electrochemical impedance spectroscopy (EIS). Hydrogen was supplied to the anode at the flow rate of 50 sccm, and the performance of LT-SOFC was evaluated at 500 °C by exposing the cathode to the atmosphere. Full article

Perovskite cathodes have emerged as a promising alternative to traditional cathode materials in low-temperature solid oxide fuel cells (LT-SOFCs) due to their exceptional catalytic properties and high oxygen reduction reaction (ORR) activity. Their fast catalytic activity and chemical stability have drawn significant attention to lowering the operating temperature of SOFCs. In this study, Ba²⁺ and Bi³⁺ are doped into LaFeO₃. The aim is to investigate the catalytic activity and electrochemical performance of LT-SOFCs. The presented cathode material is characterized in terms of phase structure, surface morphology, and interface studies before being applied as a cathode in SOFCs to measure electrochemical performance. The XPS study revealed that La_1−2xBa_xBi_xFeO₃ (x = 0.1) exhibits enriched surface oxygen vacancies compared to La_1−2xBa_xBi_xFeO₃ (x = 0.2). La_1−2xBa_xBi_xFeO₃ with (x = 0.1 and 0.2) delivers a peak power density of 665 and 545 mW cm⁻² at 550 °C, respectively. Moreover, impedance spectra confirmed that La_1−2xBa_xBi_xFeO₃ with x = 0.1 exhibits lower electrode polarization resistance (0.33 Ω cm²) compared to La_1−2xBa_xBi_xFeO₃ with x = 0.2 (0.57 Ω cm²) at 550 °C. Our findings thus confirm that LBBF cathode-based SOFCs can be considered a potential cathode to operate fuel cells at low temperatures, and it will open up another horizon in the subject of research. Full article

There is tremendous potential for both small- and large-scale applications of low-temperature operational ceramic fuel cells (LT-CFCs), which operate between 350 °C and 550 °C. Unfortunately, the low operating temperature of CFCs was hampered by inadequate oxygen reduction electrocatalysts. In this work, the electrochemical characteristics of a semiconductor heterostructure composite based on WO₃-CaFe₂O₄ deposited over porous Ni-foam are investigated. At low working temperatures of 450–500 °C, the developed WO₃-CaFe₂O₄ pasted on porous Ni–foam heterostructure composite cathode exhibits very low area-specific resistance (0.78 Ω cm²) and high oxygen reduction reaction (ORR) activity. For button-sized SOFCs with H₂ and atmospheric air fuels, we have demonstrated high-power densities of 508 mW cm⁻² running at 550 °C, and even potential operation at 450 °C, using WO₃-CaFe₂O₄ seeded on porous Ni-foam cathode. Moreover, WO₃-CaFe₂O₄ composite heterostructure with Ni foam paste exhibits very low activation energy compared to both WO₃ and CaFe₂O₄ alone, which supports ORR activity. To comprehend the enhanced ORR electrocatalytic activity of WO₃-CaFe₂O₄ pasted on porous Ni-foam heterostructure composite, several spectroscopic tests including X-ray diffraction (XRD), photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS) were used. The findings may also aid in the creation of useful cobalt-free electrocatalysts for LT-SOFCs. Full article

Mixed metallic oxides are getting increasing attention as novel electrode materials for energy conversion devices. However, low mixed ionic-electronic conductivity and high operating temperature hamper the practical applications of these devices. This study reports an effective strategy to improve the conductivity and performance of the fuel cell at low temperature by partially incorporating graphene in the Li_0.1Cu_0.2Zn_0.7-oxide (LCZ) composite. The proposed cathode material is synthesized via the cost effective conventional solid-state route. Graphene incorporated LCZ shows excellent performance, which is attributed to the favorable charge transport paths offering low area-specific resistance. An X-ray diffractometer (XRD) and scanning electron microscope (SEM) are employed for microstructural and surface morphological analyses, respectively. Electrical conductivities of all the materials are determined by the DC four probe method, and interestingly, LCZ-1.5% graphene exhibits an excellent conductivity of 3.5 S/cm in air atmosphere at a temperature of 450 °C with a minimum value of 0.057 Ωcm² area-specific resistance (ASR) that demonstrates significantly good performance. Moreover, the three-layer fuel cell device is fabricated using sodium carbonated Sm_0.2Ce_0.8O (NSDC) as an electrolyte, which can operate at low temperatures exhibiting open circuit voltage 0.95 V and shows a peak power density, i.e., 267.5 mW/cm² with hydrogen as the fuel. Full article

This study demonstrated a silver (Ag) and samarium-doped ceria (SDC) mixed ceramic and metal composite (i.e., cermet) as a cathode for low-temperature solid oxide fuel cells (LT-SOFCs). Introducing the Ag-SDC cermet cathode for LT-SOFCs revealed that the ratio between Ag and SDC, which is a crucial factor for catalytic reactions, can be tuned by the co-sputtering process, resulting in enhanced triple phase boundary (TPB) density in the nanostructure. Ag-SDC cermet not only successfully performed as a cathode to increase the performance of LT-SOFCs by decreasing polarization resistance but also exceeded the catalytic activity of platinum (Pt) due to the improved oxygen reduction reaction (ORR). It was also found that less than half of Ag content was effective to increase TPB density, preventing oxidation of the Ag surface as well. Full article

Atomic layer deposition (ALD) is performed to obtain less than 1 nm thick yttria-doped ceria (YDC) layers as cathode functional layers to increase the surface oxygen incorporation rate for low-temperature solid oxide fuel cells (LT-SOFCs). Introducing a YDC surface modification layer (SML) has revealed that the optimized yttria concentration in YDC can catalyze surface oxygen exchange kinetics at the interface between the electrolyte and cathode. The YDC SML-containing fuel cell performs 1.5 times better than the pristine fuel cell; the result is an increased exchange current density at the modified surface. Moreover, a heavily doped YDC SML degrades the performance of LT-SOFCs, owing to the weakened oxygen surface kinetics due to the increased migration energy of the oxygen ions. Full article

Low-temperature solid fuel cells (LT-SOFCs) hold remarkable promise for the cooperative corporation of small- and large-scale applications. However, the meager oxygen-reduction retort of cathode materials mires the low operating temperature conditions of SOFCs. Herein, we have developed a perovskite structured LaFeO₃ by the co-doping of Gd and Ce ions, and their electrochemical properties have been studied. The developed LaFe_0.8Gd_0.1Ce_0.1O_3-δ cathode exhibits very small-area-specific-resistance and good oxygen-reduction reaction (ORR) activity at low operating temperatures of 450–500 °C. We have demonstrated a high-power density of 0.419 W-cm⁻² with a LaFe_0.8Gd_0.1Ce_0.1O_3-δ cathode operating at 550 °C with H₂ and atmospheric air as fuels. Moreover, LaFe_0.8Gd_0.1Ce_0.1O_3-δ exhibits high activation energy as compared to individual LaFeO_3, which helps to promote ORR activity. Various spectroscopic measurements such as X-ray diffraction, SEM, EIS, UV-visible, TGA, Ramana, and photoelectron spectroscopy were employed to understand the improved ORR electrocatalytic activity of Gd and Ce co-doped LaFeO₃ cathode. The results can further help to develop functional cobalt-free electro-catalysts for LT-SOFCs. Full article

Lately, ceramic fuel cells (CFCs) have held exceptional promise for joint small- and large-scale applications. However, the low-oxygen reduction response of cathode materials has hindered the low operating temperature of CFCs. Herein, we have developed a semiconductor based on La and Ce co-doped SrCoO₃ and embedded them in porous Ni-foam to study their electrochemical properties. The porous Ni-foam-pasted La_0.2Sr_0.8Co_0.8Ce_0.2O_3‒δ cathode displays small-area-specific resistance and excellent ORR (oxygen reduction reaction) activity at low operating temperatures (LT) of 450–500 °C. The proposed device has delivered an impressive fuel cell performance of 440 mW-cm⁻², using La_0.2Sr_0.8Co_0.8Ce_0.2O_3−δ embedded on porous Ni-foam substrate cathode operation at 550 °C with H₂ fuel and atmospheric air. It even can function well at a lower temperature of 450 °C. Moreover, La_0.2Sr_0.8Co_0.8Ce_0.2O_3−δ embedded on porous Ni-foam shows very good activation energy compared to individual SrCoO₃ and La_0.1Sr_0.9Co_0.9Ce_0.1O_3−δ embedded on porous Ni-foam, which help to promote ORR activity. Different characterization has been deployed, likewise: X-ray diffraction, photoelectron-spectroscopy, and electrochemical impedance spectroscopy for a better understanding of improved ORR electrocatalytic activity of prepared La_0.2Sr_0.8Co_0.8Ce_0.2O_3−δ embedded on porous Ni-foam substrate. These results can further help to develop functional cobalt-free electrocatalysts for LT-SOFCs. Full article

Enabling fast ionic transport at a low-temperature range (400–600 °C) is of great importance to promoting the development of solid oxide fuel cells (SOFCs). In this study, a layer-structured LiCoO₂–LiFeO₂ heterostructure composite is explored for the low-temperature (LT) SOFCs. Fuel cell devices with different configurations are fabricated to investigate the multifunction property of LiCoO₂–LiFeO₂ heterostructure composites. The LiCoO₂–LiFeO₂ composite is employed as a cathode in conventional SOFCs and as a semiconductor membrane layer in semiconductor-based fuel cells (SBFCs). Enhanced ionic conductivity is realized by a composite of LiCoO₂–LiFeO₂ and Sm³⁺ doped ceria (SDC) electrolyte in SBFC. All these designed fuel cell devices display high open-circuit voltages (OCVs), along with promising cell performance. An improved power density of 714 mW cm⁻² is achieved from the new SBFC device, compared to the conventional fuel cell configuration with LiCoO₂–LiFeO₂ as the cathode (162 mW cm⁻² at 550 °C). These findings reveal promising multifunctional layered oxides for developing high-performance LT–SOFCs. Full article

Layered perovskite oxides are considered as promising cathode materials for the solid oxide fuel cell (SOFC) due to their high electronic/ionic conductivity and fast oxygen kinetics at low temperature. Many researchers have focused on further improving the electrochemical performance of the layered perovskite material by doping various metal ions into the B-site. Herein, we report that Sc³⁺ doping into the layered perovskite material, PrBaCo₂O_5+δ (PBCO), shows a positive effect of increasing electrochemical performances. We confirmed that Sc³⁺ doping could provide a favorable crystalline structure of layered perovskite for oxygen ion transfer in the lattice with improved Goldschmidt tolerance factor and specific free volume. Consequently, the Sc³⁺ doped PBCO exhibits a maximum power density of 0.73 W cm⁻² at 500 °C, 1.3 times higher than that of PBCO. These results indicate that Sc³⁺ doping could effectively improve the electrochemical properties of the layered perovskite material, PBCO. Full article