Performance Of Solid Oxide Fuel Cells Research Articles

Evaluating the influence of working parameters on the efficiency of a solid oxide fuel cell by conducting sensitivity analysis using electrochemical and thermodynamic modeling

AbstractThis research article presents an investigation conducted through a numerical model to analyze the influence of various operational parameters on the performance of solid oxide fuel cells (SOFCs). The parameters studied include operating temperature, current density, pressure, steam‐to‐carbon ratio, and fuel utilization. The electrochemical model employed the Butler‐Volmer equation, Fick's model, and Ohm's law to calculate concentration, activation, and ohmic losses. The primary focus was on evaluating the generated power and electrical efficiency as performance metrics. The study revealed that increasing operating temperature and pressure resulted in higher power generation and specific optimum points were identified for optimal SOFC operation. Notably, the highest power generated was 812 kW, achieved at an operating temperature of 950 K and a current density of 18100 A/m2. Additionally, decreasing the fuel utilization factor to 55% at 15250 A/m2 led to a power output of 706 kW. Similarly, at a current density of 17150 A/m2 and a pressure of 400 kPa, the fuel cell generated about 780 kW of power. Furthermore, the research demonstrated that reducing the steam‐to‐carbon ratio increased power generation, with an optimum power output of 704 kW achieved at a current density of 16000 A/m2 and a low steam‐to‐carbon ratio. Notably, this point also showcased the improved electrical efficiency of the solid oxide fuel cell. Overall, this study underscores the significance of specific operational factors that significantly impact SOFC performance. By comprehending these parameters, it becomes possible to enhance the utilization of solid oxide fuel cells across various applications.

Investigating the Effects of the Physicochemical Properties of Cellulose-Derived Biocarbon on Direct Carbon Solid Oxide Fuel Cell Performance.

This paper presents a study of the characteristic effects of the physicochemical properties of microcrystalline cellulose and a series of biocarbon samples produced from this raw material through thermal conversion at temperatures ranging from 200 °C to 850 °C. Structural studies revealed that the biocarbon samples produced from cellulose had a relatively low degree of graphitization of the carbon and an isometric shape of the carbon particles. Based on thermal investigations using the differential thermal analysis/differential scanning calorimeter method, obtaining fully formed biocarbon samples from cellulose feedstock was possible at about 400 °C. The highest direct carbon solid oxide fuel cell (DC-SOFC) performance was found for biochar samples obtained via thermal treatment at 400-600 °C. The pyrolytic gases from cellulose decomposition had a considerable impact on the achieved current density and power density of the DC-SOFCs supplied by pure cellulose samples or biochars derived from cellulose feedstock at a lower temperature range of 200-400 °C. For the DC-SOFCs supplied by biochars synthesised at higher temperatures of 600-850 °C, the "shuttle delivery mechanism" had a substantial effect. The impact of the carbon oxide concentration in the anode or carbon bed was important for the performance of the DC-SOFCs. Carbon oxide oxidised at the anode to form carbon dioxide, which interacted with the carbon bed to form more carbon oxide. The application of biochar obtained from cellulose alone without an additional catalyst led to moderate electrochemical power output from the DC-SOFCs. The results show that catalysts for the reverse Boudouard reactions occurring in a biocarbon bed are critical to ensuring high performance and stable operation under electrical load, which is crucial for DC-SOFC development.

A new highly active and CO2-stable heterostructure cathode material for solid oxide fuel cells developed from bismuth ion-modified cation-deficient Nd0.9BaCo2O5+δ

Efficient oxygen reduction kinetics as well as excellent stability are the main goals of current electrode materials for solid oxide fuel cells (SOFCs). Here, we present the latest findings regarding the augmentation of performance in SOFC through utilization of a novel heterogeneous cathode, consisting of an excess cation-deficient double perovskite Nd0.9BaCo2O5+δ (NBC90) backbone and in situ exsolved BaCo1-yBiyO3-x nanoparticles modified by bismuth (NBC90+B). The anisotropic growth of such self-assembled nanoparticles and the formation of multiple heterointerfaces exhibit an extremely strong activation effect. The in situ formed BaCo1-yBiyO3-x nanoparticles and cation-deficient NBC90 parental perovskite significantly enhance the catalytic activity and durability of the cathode toward oxygen reduction. The structural stability and CO2 tolerance of the cathode are greatly enhanced, which is attributed to the penetration of the high acidic Bi ions in the separated phase and the synergistic effect of the two-phase interface. The results unequivocally demonstrate the exceptional stability and efficiency of the NBC90+B composite as a promising cathode candidate for SOFCs.

Modeling and Analysis of Polarization Losses in Solid Oxide Fuel Cells with Siloxane Contamination

In this study, the degradation of the solid-oxide fuel cell (SOFC) nickel-yttria stabilized zirconia anode under decamethyltetrasiloxane (L4) contamination is examined with experiments and modeling. A model is developed for the polarization losses based on the charge transfer coefficient, α, and diffusion layer thickness, δ, and fitted to the experimental data to understand how the siloxane degrades the SOFC performance with time. The results of the model indicate that the total polarization losses increase approximately 44% over the course of the 180 min experiment at 350 mA cm−2. Activation losses dominate the polarization losses initially but decrease in their total contribution while concentration losses increase. Scanning electron microscopy (SEM) with wavelength dispersive X-ray spectroscopy (WDS) elemental mapping indicates that silicon deposition is highest at the outer edge of the anode and forms a barrier layer to fuel diffusion, increasing concentration losses. When the model is applied to other previous D4 and L4 siloxane experiments conducted over a period of 40 h, similar trends in polarization losses are observed. Polarization losses increase more rapidly with D4 compared to L4 siloxane contamination, with concentration losses increasing the fastest with both types of siloxane.

A Dynamic Analysis of Biomethane Reforming for a Solid Oxide Fuel Cell Operating in a Power-to-Heat System Integrated into a Renewable Energy Community

A Dynamic Analysis of Biomethane Reforming for a Solid Oxide Fuel Cell Operating in a Power-to-Heat System Integrated into a Renewable Energy Community

Research on the effect of connected cable-type channel structure and flow field arrangement on the performance of SOFC

In order to address Solid oxide fuel cells(SOFC) the issues of uneven gas distribution and low fuel utilization rate in conventional straight-channel. In this research, a connected cable-type channel with enhanced connectivity and broader radiation coverage was developed. The research revealed that in a singular flow channel scenario, the distribution of oxygen on the electrode within the connected cable-type channel exhibited greater uniformity compared to the conventional straight-channel design. The gas utilization rate is increased by 2.38% compared with the conventional straight-channel, and the output power density is increased by 8.55%. In the flow field, it is observed that the gas distribution on the cathode side of connected cable-type channel is significantly superior to that of the conventional straight-channel. In the case of a parallel flow field, the output power of the connected cable channel increases by 8.39% compared to the conventional straight channel, while the serpentine channel shows an increase of 11.65% in output power. Then, the impact of the flow field combination on the flow field was investigated. It was discovered that the output power of the cell could reach up to 5158.17 W/m2 when the serpentine-parallel staggered flow field distribution structure was utilized. This output was 11.33% higher than that of the parallel flow field.

Numerical study of electrode permeability influence on planar SOFC performance

A solid oxide fuel cell (SOFC) is a clean and very efficient electrochemical conversion device, which generates electricity directly from fuel electrochemical oxidation. In this paper, a three dimensional numerical model has been developed in order to analyse the role of some thermophysical and morphological parameters on the performance of the SOFC cell. In particular, we studied the effect of the variation of permeability of the electrodes: fuel distribution, ionic and electric current density, pressure and diffusion flux are analyzed and compared. The volume fraction of the ionic and electronic phase in the electrodes is studied using a parametric study. It was shown that the current density enhanced by decreasing the permeability, up to a defined value, and it diminished with very small permeability. A remarkable influence of pressure and diffusion of species on the performance of the cell, with the variation of permeability, has been recognized. Varying the permeability in the active layer of electrodes has a large impact on the current density, connected to the volume fraction of ionic phase. This study permits to comprehend the relationship between the performance and microstructure of SOFCs. Meanwhile, it furnishes theoretical guidance for an optimum design of the electrode permeability.

Study on expansion characteristics of Al–Al2O3 composite seals for intermediate‐temperature solid oxide fuel cell

AbstractAl2O3‐based composite seal with 10 wt% Al powder addition (A10) possesses excellent plastic and mechanical performance under wide temperature range of solid oxide fuel cell. The thickening phenomenon of A10 seal between 250°C–400°C and 600°C–750°C is caused by the thermal expansion of organic additives and the volume expansion when solid–liquid Al react with oxygen to form Al2O3. The thickness change rate reaches the maximum which is about 5% at 300°C and is about 4.46% at 650°C. The Gibbs free energy for reaction between Al and Al2O3 in the temperature range of 523–1 023 K is all less than 0, which is proved by the fact that A10 exhibits excellent self‐expansion and thermodynamic properties in the solid oxide fuel cell operating temperature.

Investigation of a solid oxide fuel cell integrated into an internal combustion engine with carbon capture for maritime applications

The significance of limiting greenhouse gas emissions has grown in the maritime sector and regulations in this regard have become increasingly stringent. This leads to the need for new and more environmentally friendly power sources, and technologies to be used in ships. Fuel cells and carbon capture systems can enable ships to both meet the International Maritime Organization’s emissions regulations and contribute to a sustainable environment by reducing greenhouse gas emissions. In this study, the solid oxide fuel cell is electrochemically, and thermodynamically modeled and integrated into the internal combustion engine for maritime applications. Reformed natural gas is used as fuel, so the steam reforming and the carbon capture and storage systems are also integrated into the solid oxide fuel cell and internal combustion engine power system. Integrated systems are simulated and energy, exergy, economy, and environmental analyses are carried out. The effects of solid oxide fuel cell operating temperature, current density, operating time due to degradation, and the use of hydrogen instead of natural gas on analyses results are investigated. The findings obtained in this study showed that the proposed integration could reduce carbon dioxide emissions by 76.1 per cent, while the hydrogen-fuelled alternative system could reduce carbon dioxide emissions by 96.9 per cent at an operating lifetime of 35,000 h for the solid oxide fuel cell. Given the fuel cell degradation, the average overall energy efficiencies of the systems were 44.1 per cent and 57.5 per cent, respectively, while the cost of the proposed system was 41.1 per cent lower than the hydrogen-fuelled alternative. Hydrogen-fueled alternative system was closer to the net zero target in emission and had higher efficiencies, the proposed system might be a more effective solution in the transition to the net zero target because of its lower volume and mass requirements and lower costs.

Three-Dimensional-Printed Composite Structures: The Effect of LSCF Slurry Solid Loading, Binder, and Direct-Write Process Parameters.

In this research, a direct-write 3D-printing method was utilized for the fabrication of inter-digitized solid oxide fuel cells (SOFCs) using ceramic materials. The cathode electrode was fabricated using the LSCF (La0.6Sr0.2Fe0.8Co0.2O3-δ) slurry loading and the Polyvinyl butyral (PVB) binder. The rheological parameters of slurries with varying LSCF slurry loading and PVB binder concentration were evaluated to determine their effect on the cathode trace performance in terms of microstructure, size, and resistance. Additionally, the dimensional shrinkage of LSCF lines after sintering was investigated to realize their influence on cathode line width and height. Moreover, the effect of the direct-write process parameters such as pressure, distance between the nozzle and substrate, and speed on the cathode line dimensions and resistance was evaluated. LSCF slurry with 50% solid loading, 12% binder, and 0.2% dispersant concentration was determined to be the optimal value for the fabrication of SOFCs using the direct-write method. The direct-write process parameters, in addition to the binder and LSCF slurry concentration ratios, had a considerable impact on the microstructure of cathode lines. Based on ANOVA findings, pressure and distance had significant effects on the cathode electrode resistance. An increase in the distance between the nozzle and substrate, speed, or extrusion pressure of the direct writing process increased the resistance of the cathode lines. These findings add to the ongoing effort to refine SOFC fabrication techniques, opening the avenues for advanced performance and efficiency of SOFCs in energy applications.

Structural and electrochemical evaluation of symmetrical and fuel flexible perovskite electrode for low temperature solid oxide fuel cell

Various disadvantages such as indolent oxidation/reduction and carbon-hydrogen (C–H) activation has hindered the commercialization of solid oxide fuel cells (SOFCs) operated with multi fuels at low temperatures (i.e. 400-700)°C. Extensive efforts have been made for the efficient performance of SOFCs by utilizing safe and cheap hydrocarbon fuels at low temperatures. In the current investigation, electrochemical performance of novel anode and cathode material SrMo0.5Fe0.5O3-δ (SMFO) is evaluated in the presence of multi-fuels such as hydrogen (gaseous), ethanol (liquid) and sub-bituminous coal (solid) at low temperature ∼ 700 °C. SMFO (synthesized through solid state reaction route) is thoroughly investigated via X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The average particle size measured is in the range from (60–90) nm. The electrical conductivity and power density is obtained between (190–389) S/cm and (994–1796) × 10−3 W/cm2 respectively among the various fuels. SMFO nanomaterial exhibits greater electrical conduction ∼390Scm−1 and power density ∼1687 × 10−3W/cm2 with ethanol to be utilized as fuel. The activation energies for SMFO are found to be (1.06, 0.65, 0.56) eV in the presence of hydrogen, ethanol and coal respectively. The active conduction and improved power densities make the fabricated nanomaterial well suited for SOFCs (at low temperature) both as cathode and anode with multi-fuel consumption.

Enhanced performance of solid oxide fuel cells using highly conductive Ca2+ and F− co-doped Gd0.2Ce0.8O1.9 buffer layer

Gadolinium-doped ceria (GDC) is the most widely used buffer layer to prevent the reaction between YSZ electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode for commercial solid oxide fuel cell (SOFC). However, conductivity and sintering activity are vital to cell performance. In this paper, Ca2+ and F− co-doped GDC (Ca0.03Gd0.17Ce0.8F0.06O1.84-δ, CGDCF) is used as a buffer layer to improve the performance and stability of SOFC. The co-doped F− and Ca2+ significantly improve the sintering properties and oxygen ion transport of traditional GDC material. Meanwhile, the optimized sintering temperature is 1300 °C, with the lowest ohmic resistance. The peak power density of a cell with a CGDCF buffer layer reaches 1.809 W cm−2 at 850 °C, which is 37 % higher than that of GDC. In addition, the cell with the CGDCF buffer layer exhibits excellent stability during the 150 h test owing to the lower migration of La and Sr elements. Thus, the Ca2+ and F− co-doped GDC oxide emerges as a promising material for buffer layer applications.

Highly functional molten sodium hydroxide-BaZrO3 composite electrolyte with hybrid ionic conductivity for low-temperature solid oxide fuel cells

Proton-conducting barium zirconate perovskite attracts considerable attention as an electrolyte for solid oxide fuel cells (SOFCs). To obtain BaZrO3-based electrolytes with high ionic conductivity at low temperatures, composite electrolytes named BaZrO3+x wt% NaOH are designed and synthesized. A study is conducted to explore the effects of molten-state NaOH and a small amount of Na2CO3 generated during SOFC operation on the performance of composite electrolytes systematically. As a result of the addition of NaOH, the composite electrolyte is created with rich surfaces and solid-liquid interfaces, compared to traditional condensed electrolytes.The solid-liquid interface can serve as a high-speed ion conduction channel. In-situ surface oxygen deficiency induced by NaOH and the bridge function of carbonate enable rapid ion migration along the interface of the composite electrolyte. The fuel cell with the prepared electrolyte can deliver an excellent maximum power density (MPD) of 1039 mW cm-2 at 550 °C. At 350 °C, the cells are also able to show a very impressive power density of 365 mW cm-2. The concise design, convenient preparation process, and outstanding performance of the fuel cell collectively offer an effective strategy for advancing the manufacture of electrolyte materials for low-temperature operation.

A Review on Solid Oxide Fuel Cell Technology: An Efficient Energy Conversion System

The increasing global dependence on fossil fuels for energy has prompted researchers to explore alternative power generation sources that offer higher efficiency, cost-effectiveness, and low environmental impact. Developed countries have been making continuous efforts to reduce their reliance on depleting fossil fuel sources to curb carbon emissions. As a result, hydrogen has gained significant attention among researchers as a potential future fuel that meets all the necessary criteria. Many countries aiming for a hydrogen economy have invested in research on fuel cells. Among various fuel cells, the solid oxide fuel cell (SOFC) has emerged as a commercially viable power source at a small scale. This paper provides an extensive review of the components, materials, design, operation, and integration strategies of SOFCs with existing thermal-based power plants. The performance and prospects of various SOFCs in standalone and hybrid modes are summarized, along with the limitations. Additionally, the research and commercialization efforts that can enhance the potential applications of SOFCs as a sustainable and reliable system in the long term are outlined.

Coupled Electrochemical-Thermo-Stress Analysis for Methanol-Fueled Solid Oxide Fuel Cells

A three-dimensional model of a methanol-fueled solid oxide fuel cell (SOFC) that sufficiently considers the rib structure to understand the effects of operating conditions on a methanol-fueled SOFC is developed. The model considers the coupling of electrochemical reactions, mass transport, heat transfer, and thermal stress. The overall performance of the methanol-fueled SOFC is investigated under the influence of operating voltage, steam-to-carbon ratio, and porosity. The results indicate that as the operating voltage increases, the overall anode switches from exothermic to endothermic, and the stress of the anode first decreases and then increases. As the steam-to-carbon ratio increases, the overall temperature of the anode decreases. However, when the steam-to-carbon ratio is less than 1, the temperature at the inlet is lower than the ambient temperature. Meanwhile, the first principal stress on the anode increases as the steam-to-carbon ratio increases. Increasing the porosity reduces the length of the three-phase boundary, thereby decreasing the current density and the overall temperature and thermal stress on the anode. This study revealed the effects of operating conditions on the methanol-fueled SOFC, especially on the rib, and contribute to controlling the operant conditions for SOFC fueled by a mixture of steam and methanol.

Thermal Stress in Full-Size Solid Oxide Fuel Cell Stacks by Multi-Physics Modeling

Mechanical failures in the operating stacks of solid oxide fuel cells (SOFCs) are frequently related to thermal stresses generated by a temperature gradient and its variation. In this study, a computational fluid dynamics (CFD) model is developed and further applied in full-size SOFC stacks, which are fully coupled and implemented for analysis of heat flow electrochemical phenomena, aiming to predict thermal stress distribution. The primary object of the present investigation is to explore features and characteristics of the thermal stress influenced by electrochemical reactions and various transport processes within the stacks. It is revealed that the volume ratio of the higher thermal stress region differs nearly 30% for different stack flow configurations; the highest probability of potential failure appears in the cell cathodes; the more cells applied in the stack, the greater the difference in the predicted temperature/thermal stress between the cells; the counter-flow stack performs the best in terms of output power, but the predicted thermal stress is also higher; the cross-flow stack exhibits the lowest thermal stress and a lower output power; and although the temperature and thermal stress distributions are similar, the differences between the unit cells are bigger in the longer stacks than those predicted for shorter stacks. The findings from this study may provide a useful guide for assessing the thermal behavior and impact on SOFC performance.

Cation doping and oxygen vacancies in the orthorhombic FeNbO4 material for solid oxide fuel cell applications: A density functional theory study.

The orthorhombic phase of FeNbO4, a promising anode material for solid oxide fuel cells (SOFCs), exhibits good catalytic activity toward hydrogen oxidation. However, the low electronic conductivity of the material specifically in the pure structure without defects or dopants limits its practical applications as an SOFC anode. In this study, we have employed density functional theory (DFT + U) calculations to explore the bulk and electronic properties of two types of doped structures, Fe0.9375A0.0625NbO4 and FeNb0.9375B0.0625O4 (A, B = Ti, V, Cr, Mn, Co, Ni) and the oxygen-deficient structures Fe0.9375A0.0625NbO3.9375 and FeNb0.9375B0.0625O3.9375, where the dopant is positioned in the first nearest neighbor site to the oxygen vacancy. Our DFT simulations have revealed that doping in the Fe sites is energetically favorable compared to doping in the Nb site, resulting in significant volume expansion. The doping process generally requires less energy when the O-vacancy is surrounded by one Fe and two Nb ions. The simulated projected density of states of the oxygen-deficient structures indicates that doping in the Fe site, particularly with Ti and V, considerably narrows the bandgap to ∼0.5eV, whereas doping with Co at the Nb sites generates acceptor levels close to 0eV. Both doping schemes, therefore, enhance electron conduction during SOFC operation.

Electricity and hydrogen production by integrating two kinds of fuel cells with copper chlorine thermo-chemical cycle

An innovative cogeneration system based on a solid oxide fuel cell (SOFC) and copper chlorine cycle is being investigated. Instead of directly making electricity by any thermodynamic cycle or thermoelectric generator, the waste heat from SOFC should be used to make hydrogen through the copper-chlorine cycle (Cu–Cl). A portable polymer exchange membrane fuel cell (PEMFC) has been suggested due to its compatibility with portable and non-portable applications. The obtained results reveal that increasing the current density of SOFC results in higher methane consumption, output power, overpotentials, and hydrogen production. Furthermore, temperature variation does not have as much influence on power generation and efficiency as current density, where the system efficiency, when operating at 0.7 A/cm2 and SOFC operating temperature of 900–1200 K, varies between 40.4 % and 46.3 %. Regarding the methane flow rate, as it increases, the output power increases as well, but the efficiency falls. The system's greatest power output is 677.5 kW and occurs at a methane flow rate of 2.13 mol/s, although the system efficiency is just 39.7 % at that point. Most importantly, SOFC generates nearly 65 % of the total power, while PEMFC generates around 35 %. Therefore, the percentage of additional power that PEMFC can produce is around 55 %.

Techno-Economic and Environmental Analysis of a Hybrid Power System Formed From Solid Oxide Fuel Cell, Gas Turbine, and Organic Rankine Cycle

Abstract Distributed energy technology is an essential pathway for future advancements in the field of energy technology. In the present study, organic Rankine cycle (ORC) is integrated with solid oxide fuel cell (SOFC)-gas turbine (GT) hybrid power system. The conventional metrics employed for assessing the performance of SOFCs, gas turbines, and organic Rankine cycles, such as voltage and gross real efficiencies, have some limitations as indices of merit. Contemporary second law concepts and economic and environmental analysis have been used to enhance hybrid power system evaluation. R1233zd(E) has been selected as the ORC working fluid. The outcomes reveal that, under certain conditions, the present configuration may reach 55.67% energy efficiency and 53.55% exergy efficiency. Economic and environmental analysis shows that the hybrid system's total cost rate and Emissions of CO2 gas (EMI) under design conditions are 36.09 $/h and 355.8 kg/MWh, respectively. Thermodynamic evaluation of present SOFC-GT-ORC configuration shows 11.72% improvement in exergy efficiency compared to hybrid SOFC-GT cycle. Consequently, the hybrid SOFC-GT-ORC system is far better than the hybrid SOFC-GT system. In the future, other ORC fluids like R123, R601a, and R245fa can be used as ORC fluids.

Novel sr-doped NdMn0.5Cr0.5O3-δ electrodes for symmetrical solid oxide fuel cell

Solid oxide fuel cells (SOFCs) have emerged as promising energy conversion devices, offering high efficiency and environmental sustainability. Efficient electrode materials are crucial for the overall cell performance of SOFCs. Perovskite type Nd1-xSrxMn0.5Cr0.5O3-δ (x = 0.25, 0.5) (NSCM25, NSCM50) was synthesized via conventional solid-state reaction technique. Structural, thermal and electrochemical characterizations were performed using X-ray diffraction, thermogravimetric analysis, conductivity measurements, scanning electron microscope, thermal expansion coefficient analysis and impedance spectroscopy. Structural analysis revealed that both compositions exhibit orthorhombic symmetry in the Pbnm space group. Thermogravimetric analysis (TGA) indicated minimal weight changes in both pre-reduced and as-prepared samples. The electrical conductivities in air at 600 ℃ were found to be 1.69 S/cm for NSCM25 and 4.91 S/cm for NSCM50, with a decrease observed under reduced oxygen partial pressure. Polarization resistance (Rp) analysis was conducted on symmetrical cells composed of NSCM25|GDC|NSCM25, NSCM50|GDC|NSCM50, NSCM25|YSZ|NSCM25, and NSCM50|YSZ|NSCM50. At 900 ℃, the polarization resistances were 0.12 Ωcm2, 0.21 Ωcm2, 0.11 Ωcm2, and 0.67 Ωcm2, respectively. The results suggest that NSCM25 and NSCM50 hold promise as electrode materials for symmetrical solid oxide fuel cells (SSOFC) employing YSZ or GDC electrolyte.