Design, fabrication, and characterization of a planar, silicon-based, monolithically integrated micro laminar flow fuel cell with a bridge-shaped microchannel cross-section

We report the fabrication of a planar, silicon-based, monolithically integrated micro laminar flow fuel cell (μLFFC) using standard MEMS and IC-compatible fabrication technologies. The μLFFC operates with acid supported solutions of formic acid and potassium permanganate, as a fuel and oxidant respectively. The micro-fuel cell design features two in-plane anodic and cathodic microchannels connected via a bridge to confine the diffusive liquid-liquid interface away from the electrode areas and to minimize crossover. Palladium high-active-surface-area catalyst was selectively integrated into the anodic microchannel by electrodeposition, whereas no catalyst was required in the cathodic microchannel. A three-dimensional (3D) diffusion-convection model was developed to study the behavior of the diffusion zone and to extract appropriate cell-design parameters and operating conditions. Experimentally, we observed peak power densities as high as 26 mW cm⁻² when operating single cells at a flow rate of 60 μL min⁻¹ at room temperature. The miniature membraneless fuel cell design presented herein offers potential for on-chip power generation, which has long been prohibited by integration complexities associated with the membrane.     

Experimental study on dual recirculation of polymer electrolyte membrane fuel cell

Durability and start-up ability in sub-zero environment are two technical bottlenecks of vehicular polymer electrolyte membrane (PEM) fuel cell systems. With exhaust gas recirculation on the anode and cathode side, the cell voltage at low current density can be reduced, and the membrane can be humidified without external humidifier. They may be helpful to prolong the working lifetime and to promote the start-up ability. This paper presents an experimental study on a PEM fuel cell system with anodic and cathodic recirculation. The system is built up based on a 10 kW fuel cell stack, which consists of 50 cells and has an active area of 261 cm². A cathodic recirculation pump and a hydrogen recirculation pump are utilized on the cathode and anode side, respectively. Key parameters, e.g., stack current, stack voltage, cell voltage, air flow, relative humidity on the cathode side, oxygen concentration at the inlet and outlet of the cathode side, are measured. Results show that: 1) with a cathodic recirculation the system gets good self-humidification effect, which is similar to that with an external humidifier; 2) with a cathodic recirculation and a reduction of fresh air flux, the cell voltage can be obviously reduced; 3) with an anodic recirculation the cell voltage can also be reduced due to a reduction in the hydrogen partial pressure, the relative humidity on the cathode side is a little smaller than the case with only cathode recirculation. It indicates that, for our stack the cathodic recirculation is effective to clamp cell voltage at low current density, and a self-humidification system is possible with cathodic recirculation. Further study will focus on the dynamic model and control of the dual recirculation fuel cell system.     

Ultrathin nitrogen doped carbon layer stabilized Pt electrocatalyst supported on N-doped carbon nanotubes

The enhancements in fuel cell performance and durability are crucial for the commercialization of polymer electrolyte fuel cells (PEFCs). Here, we deposit platinum nanoparticles on nitrogen doped carbon nanotubes (N-CNT) and continuously coat the electrocatalyst with nitrogen doped carbon (NC) layer derived from the carbonization of poly(vinyl pyrrolidone) (PVP). The NC-coated electrocatalyst shows stable electrochemical surface area (ECSA) during the potential cycling from 0.6 V to 1.0 V vs. RHE; while, the commercial and non-coated electrocatalysts lose 50% and 33% of initial ECSAs, respectively. Moreover, the NC-coated electrocatalyst shows higher oxygen reaction reduction (ORR) activity compared to non-coated electrocatalyst due to the additional nitrogen atoms in the electrocatalyst. The maximum power density of the coated electrocatalyst reaches 676 mW cm^?2 with Pt loading of 0.1 mg cm^?2, indicating that the mass power density of the electrocatalyst is one of the highest values in recently published literature. The NC layer is significantly important for simultaneous enhancements in durability and fuel cell performance.     

Studies of performance decay of Pt/C catalysts with working time of proton exchange membrane fuel cell

Life test of the proton exchange membrane fuel cell (PEMFC) was carried out at a current density of 160 mA cm⁻². After an operation up to 2250 h, the performance of the single PEMFC shown by a current-time curve did not decay significantly. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize both anodic and cathodic catalysts before and after the life test. Cyclic voltammetric (CV), polarization, and power density curves were plotted with the cell at different periods during long-term operation. The results showed that the electrochemically active surface areas (S_EAS) of anodic and cathodic catalysts firstly increased, and then decreased with the operation time. The S_EAS loss of anodic catalyst was evidently smaller than that of cathodic one. The thickness of Nafion^® film decreased with working time as shown by SEM. The particle size of cathodic Pt/C catalyst was evidently bigger than that of anodic one. The degradation of cathodic catalyst for oxygen electroreduction was one of the main factors affecting the performance decay of PEMFC.     

A woven thread-based microfluidic fuel cell with graphite rod electrodes

A woven thread-based microfluidic fuel cell based on graphite rod electrodes is proposed. Both inter-fiber gaps and inter-weave spaces could provide flow channels for the liquid transport through the woven cotton thread. Therefore, no external pumps are required to maintain the co-laminar flow, benefiting for the integration and miniaturization. In the experiment, sodium formate and hydrogen peroxide are used as fuel and oxidant, respectively. To improve the electrochemical reaction kinetics, KOH and H₂SO₄ serve as supporting electrolyte at the anode and cathode, respectively. Na₂SO₄ solution is used as the electrolyte to separate the cathode and anode in the middle flow channel and alleviate the reactant crossover. The open circuit potential of the fuel cell achieves 1.44 V and the maximum current density and power density are 56.6 mA cm^?2 and 20.7 mW cm^?2, respectively. Moreover, the cell performance reduces with increasing the electrode distance due to a high ohmic resistance. With an increase in the fuel concentration from 1 M to 4 M, the performance increases and it reduces with further increasing to 6 M owing to a correspondingly low flow rate. The highest fuel utilization rate reaches 10.9% at 4 M fuel concentration.     

Fabrication and characteristics of a composite cathode of sulfonated polyaniline and Ramsdellite–MnO2 for a new rechargeable lithium polymer battery

The ionic conductivity of a polyacrylonitrile (PAN)-based solid polymer electrolyte is 1.4×10⁻³ S cm⁻¹, which is sufficient for the electrolyte to be used in a rechargeable lithium polymer battery. The anodic stability of the solid polymer electrolyte is over 4.6 V (vs. Li/Li⁺). A reduced, highly sulfonated form of polyaniline (SPAn) and Ramsdellite–MnO₂ (R-MnO₂) are synthesized and used as a cathodic material for a rechargeable lithium polymer battery. Three kinds of cathodes are prepared from SPAn, R-MnO₂, and a mixture of SPAn and R-MnO₂. The electrochemical properties and diffusion coefficient of lithium ions in each cathode, and the interface between the solid polymer electrolyte and each cathode are investigated by cyclic voltammetry and impedance spectroscopy. The redox processes of the SPAn cathode are two-step reactions. The cathodic and anodic peak currents increase as the cycle number increases. In the redox processes of the R-MnO₂ cathode, the cathodic peak current on the second cycle is 62% of that on the first cycle. The Li/R-MnO₂ battery has a very high initial discharge capacity, but very poor cycleability. For the composite cathode, the cathodic peak current on the second cycle is 72% of that on the first cycle, i.e., higher than that for the R-MnO₂ cathode. The diffusion coefficient of the composite cathode during the discharge process is close to the sum of each variation in the SPAn and R-MnO₂ cathodes. The instability of the R-MnO₂ cathode at x=0.3 and x=0.2 during the charge process is not observed with the composite cathode. The discharge–charge performance of three types of battery are investigated. The initial discharge capacity of the Li/composite cathode battery is 97.0 m Ah g⁻¹. This battery has higher discharge capacity than the Li/SPAn battery (66.8 m Ah g⁻¹), and better cycleability than the Li/R-MnO₂ battery.     

Semiconductor electrolyte for low-operating-temperature solid oxide fuel cell: Li-doped ZnO

Semiconductors have been successfully demonstrated as the electrolytes for solid oxide fuel cells (SOFCs) in recent years. Many such semiconductors have shown their potentials as a competent ionic conductor for fuel cell operation, indicated by the appreciable ionic conduction and electrochemical performance. In the present study, we depart from traditional electrolyte concept to introduce a new semiconductor electrolyte, Li-doped ZnO to low-operating-temperature SOFCs. The used material was synthesized via a co-precipitation method and investigated from phase structure, morphology and UV–vis absorption perspectives. Utilizing Li-doped ZnO as electrolyte layer, we found the corresponding fuel cell exhibited a remarkable maximum power density of 443 mW cm^?2 along with open circuit voltage (OCV) of 1.07 V at 550 °C, and represented a lower-temperature operation feasibility with power outputs of 138–165 mW cm^?2 at 425–450 °C. Besides, high ionic conductivities of 0.028–0.087 S cm^?1 and low activation energy of 0.5 eV were also found in the synthesized Li-doped ZnO at 425–550 °C. Our investigation in terms of electrochemical impedance spectra (EIS) analysis manifested that Li-doped ZnO as the electrolyte layer boosted the electrode reactions of the device, which resulted in rather small polarization resistances and eventually realized good low-temperature performances. Further study based on the rectification characteristic of Ni/Li-doped ZnO contact verified the Schottky junction formation of Li-doped ZnO with anodic Ni, which can avoid the underlying electronic short-circuiting problem. These findings show a profound significance of using doped semiconductor for the future exploitation of SOFC electrolytes.     

Porous YFe0.5Co0.5O3 thin sheets as cathode for intermediate-temperature solid oxide fuel cells

In this work, porous YFe_0.5Co_0.5O₃ (YFC) thin sheets were synthesized by citric acid method. The crystal structure, morphology, thermal expansion, electrical conductivity, and electrochemical properties of YFC were investigated to evaluate it as a possible cathode on BaZr_0.1Ce_0.7Y_0.2O₃ (BZCY) electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). An orthorhombic perovskite structure was observed in YFC. The conductivity of YFC is 183 S cm ^?1 at 750 °C in air. The coefficient of thermal expansion of composite cathode YFC-BZCY is closer to BZCY electrolyte than YFC. The composite cathode represents a relatively low polarization resistance (R_p) of 0.07 Ω cm² at 750 °C in air due to the porous thin sheet-like cathode. The oxygen reduction reaction process and the reaction activation energy of cathode were also analyzed. An anode-supported cell of NiO-BZCY∣BZCY∣YFC-BZCY is fabricated by a simple method of co-pressing. The power density of the cell is 303 mW cm^?2 at 750 °C as the thickness of electrolyte is 400 μm. The results suggest that YFC is a promising cathode candidate for IT-SOFC.     

Fabrication of integrated BZY electrolyte matrices for protonic ceramic membrane fuel cells by tape-casting and solid-state reactive sintering

Integrated porous/dense/porous tri-layer BaZr_0.8Y_0.2O_3-δ (BZY) electrolyte asymmetrical matrices were designed for protonic ceramic membrane fuel cells (PCMFCs) and fabricated by multilayer tape-casting and solid-state reactive sintering. The effects of pore-former, sintering aid and sintering program on the microstructure of integrated electrolyte matrices (IEMs) were studied. Graphite and NiO were appropriate pore-former and sintering aid, respectively, and an accelerated heating program was more desirable. The conductivities of the IEM with designed microstructure in different atmospheres were measured by AC impedance spectroscopy at 400–600 °C. The highest conductivity of 6.9 × 10^?3 S cm^?1 at 600 °C was obtained in wet air atmosphere, and the corresponding activation energy was 0.602 eV. Gas-tightness of the IEM was confirmed by a stable open circuit voltage (OCV) of 0.97 V at 600 °C from a button fuel cell with impregnated NiO anode and BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ (BCFZY) cathode. These indicate that the fabricated BZY-based IEM has great potential for PCMFC application.     

Co-extruded dual-layer hollow fiber with different electrolyte structure for a high temperature micro-tubular solid oxide fuel cell

In this study, the phase inversion-based co-extrusion method was employed to fabricate a structural-improved electrolyte/anode dual-layer hollow fiber (HF) precursor, which was then co-sintered at 1450 °C. The electrolyte structures were thoroughly investigated by varying the loading of electrolyte material (i.e. Yttria-stabilized zirconia, YSZ) with differing particle sizes (i.e. micron, sub-micron, and nano-sized) during suspension preparation. The results showed that the most promising electrolyte layer with thin, dense, gas-tight, and defect-free properties was obtained by mixing 70% submicron-YSZ and 30% nano-YSZ in electrolyte suspension (E-0.7sub0.3nano). This electrolyte formulation co-extruded with a thick nickel-oxide-YSZ (NiO-YSZ) anode layer yielded the highest bending strength of 85 MPa, providing major mechanical strength to the HF. Besides that, the nitrogen permeability value at 2.87 × 10^?6 mol m^?2 s^?1 Pa^?1 suggested that the electrolyte was gas-tight, preventing fuel and oxidant transport. The fiber was then reduced to nickel (Ni)-cermet anode. It was developed to be a complete micro-tubular solid oxide fuel cell (MT-SOFC) by depositing the lanthanum strontium cobalt ferrite (LSCF)/YSZ cathode via brush painting on the dual-layer HF. The cell was fed with hydrogen gas and yielded an open-circuit voltage (OCV) as high as 1.06 V with maximum power density of 0.243 W cm^?2, at 875 °C. Based on this test, it was found that the electrolyte structural-modified dual-layer hollow fiber-based MT-SOFC using mixed particle sizes may result in a promising OCV. However, the relatively low value for power density may be due to a less porous anode; thus, improvements in the anode's structure are required in future research.     

Anodic inoculum pre-treatment by extracts of Azadirachta indica leaves and Allium sativum peels for improved bioelectricity recovery from microbial fuel cell

The electrogenic bacterial consortia enrichment in the anodic chamber play a crucial role in determining the efficiency of microbial fuel cell (MFC). In order to use mix anaerobic culture enriched with active electrogenic species as inoculum, suppression of methanogens is important. This investigation focuses on potential of extracts of Azadirachta indica (Neem) leaves and Allium sativum (Garlic) peels in inhibiting activity of methanogenic microorganisms in the mixed anaerobic sludge. Specific methane yields of sludge treated with neem leaves extract, garlic peel extract and untreated sludge were found to be 0.068 ± 0.08 L CH₄/g VSS.d, 0.073 ± 0.08 L CH₄/g VSS.d, and 0.193 ± 0.08 L CH₄/g VSS.d, respectively. However, the MFC operated with these pre-treated inoculums gave respective power densities of 5.6 W/m³, 5.0 W/m³, and 2.65 W/m³, respectively. Hence, it can be inferred that pre-treatment of mixed anaerobic sludge using neem leaves and garlic peels extract can be effective in enhancing power produced from MFCs.     

Samarium doped ceria-(Li/Na)2CO3 composite electrolyte and its electrochemical properties in low temperature solid oxide fuel cell

A composite of samarium doped ceria (SDC) and a binary carbonate eutectic (52 mol% Li₂CO₃/48 mol% Na₂CO₃) is investigated with respect to its morphology, conductivity and fuel cell performances. The morphology study shows the composition could prevent SDC particles from agglomeration. The conductivity is measured under air, argon and hydrogen, respectively. A sharp increase in conductivity occurs under all the atmospheres, which relates to the superionic phase transition in the interface phases between SDC and carbonates. Single cells with the composite electrolyte are fabricated by a uniaxial die-press method using NiO/electrolyte as anode and lithiated NiO/electrolyte as cathode. The cell shows a maximum power density of 590 mW cm⁻² at 600 °C, using hydrogen as the fuel and air as the oxidant. Unlike that of cells based on pure oxygen ionic conductor or pure protonic conductor, the open circuit voltage of the SDC-carbonate based fuel cell decreases with an increase in water content of either anodic or cathodic inlet gas, indicating the electrolyte is a co-ionic (H⁺/O²⁻) conductor. The results also exhibit that oxygen ionic conductivity contributes to the major part of the whole conductivity under fuel cell circumstances.     

Potassium permanganate as an electron receiver in a microbial fuel cell

Microbial fuel cells with air as a cathode electron receiver are simple systems but they need expensive catalysts. In comparison to microbial fuel cells with oxygen as an electron receiver, microbial fuel cells with potassium permanganate produce higher voltage. In this study, electrical performance of a microbial fuel cells containing anaerobic sludge and potassium permanganate as an oxidizing agent was investigated. Glucose (1 g/l) was used as a carbon and energy source. The maximum power density and current density at the maximum power density were 93.13 mW/m² and 0.030 mA/cm² with respect to a potassium permanganate concentration of 400 µM. It is observed that the maximum power density increased to 114.00 mW/m² using an acid-heat treated carbon brush anode. Also, chemical oxygen demand removal was 51% when the microbial fuel cells was operated using 400 µM of potassium permanganate.     

Remarkable ionic conductivity and catalytic activity in ceramic nanocomposite fuel cells

Although ceramic nanocomposite fuel cells (CNFCs) have attracted the attention of the fuel cell community due to their low operating temperature (<600 °C), often the performance of the cells is limited due to the low ionic conductivity of the electrolyte and the sluggish reaction kinetics at the electrodes. This results in high ohmic and charge transfer losses in the cell performance. Here we report nanocomposite electrolyte (GDC-NLC) and electrodes (NiO-GDC-NLC and LSCF-GDC-NLC as anode and cathode respectively) with enhanced ionic conductivity and catalytic activity respectively, which significantly improve the ionic transport in the electrolyte layer (ohmic losses ≈ 0.23 Ω cm²) and the reaction kinetics at the electrodes (polarization losses ≈ 0.63 Ω cm²). Microstructural and phase changes in the materials were characterized with X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry to understand the mechanisms in the cells. Our button fuel cell produced an outstanding performance of 1.02 W/cm² at 550 °C.     

Effect of MgO addition and grain size on the electrical properties of Ce0.9Gd0.1O1.95 electrolyte for IT-SOFCs

The aim of this study is to investigate the effect of grain size on the electrical properties of Ce_0.9Gd_0.1O_1.95-x mol% MgO (GDC-xMgO) and to evaluate them as electrolytes for use in intermediate-temperature solid oxide fuel cells (IT-SOFCs). For this purpose, GDC-xMgO (x = 0–15) electrolytes were synthesized by the glycine-nitrate process and sintered at different temperatures. Impedance spectroscopy measurements revealed that for each composition, the grain-boundary resistivity decreased with decreasing grain size for the samples with grain size of >0.4 μm. Much too small grain sizes (0.2 < d_g < 0.3 μm) produced an increase in grain-boundary resistivity. The addition of MgO could weaken the influence of grain sizes on the grain-boundary resistivity. The interfacial polarization resistances could be decreased by adding MgO to GDC. The GDC-1MgO sample sintered at 1200 °C exhibited the highest total conductivity of 8.11 × 10^?2 S cm^?1 at 800 °C. The maximum power density of the GDC-1MgO-based cell was 0.73 W cm^?2 at 800 °C, which was much higher than that of the GDC-based cell. The results indicated that the GDC-1MgO was a potential electrolyte for IT-SOFCs.     

Alkaline metal doped strontium cobalt ferrite perovskites as cathodes for intermediate-temperature solid oxide fuel cells

Perovskite oxides Sr_0.9K_0.1Fe_xCo_1-xO_3-δ (SKFCx, x = 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) are investigated as potential cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) on Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte. The cubic phase of the SKFCx oxides is demonstrated by x-ray diffraction. The SKFCx cathode shows good compatibility with the SDC electrolyte up to 900 °C. Among the investigated compositions, SKFC0.1 displays the highest electrical conductivity of 443–146 S·cm^?1 from 350 °C to 800 °C in flow air. The area specific resistances (ASRs) of the SKFCx (x = 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) cathodes are 0.047, 0.058, 0.066, 0.101, 0.155 and 0.175 Ω cm² at 650 °C in air on an SDC electrolyte. Among the five tested cathodes, SKFC0.1 exhibits the lowest area specific resistances between 550 °C and 750 °C, when tested on its symmetric cell configuration of cathode|SDC|cathode. The thermally stabilized cubic perovskite structure of the SKFC0.1 powder is demonstrated by high-temperature XRD. The average linear thermal expansion coefficient α_L of SKFC0.1 is 18.9$\times$10^?6 K^?1. A peak power density of 1643 mW·cm^?2 is achieved on SKFC0.1|SDC|Ni-SDC anode supported fuel cell at 650 °C. These features, and excellent electrocatalytic activity and good stability, indicate the potential of alkaline metal doped strontium cobalt ferrite perovskites are promising cathode materials for IT-SOFCs.     

The effects of polarisation on the performance of the Ba2Co9O14–Ce0.8Gd0.2O2-δ composite electrode for fuel cells and electrolysers

The potential of the [BaCoO₃]_n [BaCo₈O₁₁] family as a cathode for solid oxide fuel cells (SOFCs) or as an anode for solid oxide electrolyser cells (SOECs) is investigated via structural, microstructural and electrochemical characterisation. The crystallographic structure of the n = 1 member compound, Ba₂Co₉O₁₄ (BCO), exhibits rhombohedral symmetry and presents a microstructure consisting of large platelets. Overall, the electrochemical performance of the Ba₂Co₉O₁₄/Ce_0.8Gd_0.2O_2-δ (BCO/CGO-20) composite electrode is found to be enhanced under cathodic polarisation, while becoming impaired under anodic polarisation. The latter behaviour may result from the high local oxygen partial pressures upon increasing the applied anodic polarisation that lead to a depletion of oxygen vacancies at the electrode/electrolyte interface, thus, decreasing the ionic conductivity as well as electrocatalytic activity of this interface. This work, therefore, provides the first electrochemical analysis of the performance of BCO-based electrodes under applied polarisation conditions for SOFC and SOEC applications, and highlights the higher potential of this compound as a cathode material for intermediate-temperature solid oxide fuel cells.     

Proton exchange membrane from the blend of poly(vinylidene fluoride) and functional copolymer: Preparation,proton conductivity,methanol permeability,and stability

A polymer electrolyte membrane is considered as the heart of fuel cells. Here we report the preparation of proton exchange membranes (PEMs) of poly (vinylidene fluoride) (PVDF) blend poly (methyl methacrylate)-co-poly (sodium-4-styrene sulfonate) (PMMA-co-PSSNa) by solvent evaporation method. Three different types of PEMs have been prepared by using different ratios of PVDF and PMMA-co-PSSNa copolymer. We have investigated the effect of concentration of PVDF on water uptake, ion exchange capacity, mechanical, thermal, and oxidative stability, proton conductivity (K^m), and methanol permeability (P_M) of the blend membranes. These blend PEMs showed good physicochemical and electrochemical properties along with thermal and oxidative stability. The membrane prepared from PVDF (45% w/w) to PMMA-co-PSSNa (55% w/w) exhibited optimum P_M at room temperature (8.38 × 10^?7 cm²s^?1). This low fuel crossover and high relative selectivity can make our prepared blend membranes a potential candidate in polymer electrolyte membrane fuel cells (PEMFCs) or direct methanol fuel cells (DMFCs).     

Numerical optimization of bipolar plates and gas diffusion electrodes for PBI-based PEM fuel cells

This paper is devoted to the numerical optimization of the geometry of some key cell components (flow-field channels, current transfer ribs of bipolar plates, gas diffusion electrodes) of high-temperature PEM fuel cells using H₃PO₄-doped Poly Benzimidazole (PBI) as solid polymer electrolyte. Some design specifications as well as optimum values of key operating parameters are proposed to increase the efficiency of such fuel cells. For this purpose physicochemical model and corresponding novel effective technique for solving of 2D transport equation have been developed. Results of the numerical analysis of dependence of fuel cell performances upon the geometry of cathodic and anodic flow-field channels, operating temperature and gas diffusion electrode parameters are provided. In particular, it was demonstrated that optimum relative width of current-transfer rib (i.e. the ratio between width of rib divided to sum of widths of rib and channel) is determined mainly by competition between diffusion and current conductivity in a gas diffusion electrode and is approximately equal to 0.30–0.35 for the parameters of cell components used in this study.     

Electrochemical investigations of cobalt-free perovskite cathode material for intermediate temperature solid oxide fuel cell

A novel cobalt-free perovskite zinc-doped lanthanum strontium iron oxide (La_0.8Sr_0.2Zn_xFe_1?xO_3?δ, LSZF, x = 0.1–0.3) is synthesized and evaluated as cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC) with samarium doped ceria (SDC) electrolyte. LSZF cathode at x = 0.2 composition demonstrates the remarkable electrochemical activity at intermediate temperature (550 °C): such as, high electrical conductivity (13.63 S cm^?1), excellent thermal stability with SDC electrolyte (12.10 μK^?1), high surface area (4.52 m² g^?1), extremely reduced area specific resistance (0.69 Ω cm^?2) and low activation energy (0.117 eV). Furthermore, single fuel cells are fabricated using LSZF as a cathode, which exhibits the excellent performance by achieving the high power density of 409 mW cm^?2 under natural gas as a fuel and ambient air as an oxidant at 550 °C with good stability over 10 h. All experimental results indicate that the LSZF is a promising cathode material for natural gas based intermediate temperature fuel cell applications.