In the long-history of fuel cell R&D, the electrolyte is an essential part in a three-component configuration because it separates the anode and cathode to realize the fuel cell's functions. We ...report here non-electrolyte separator fuel cells (NEFCs) compared with electrolyte based fuel cells (EBFCs). The NEFC consists of single- or dual-components based on mixed ionic and semi-conductors but with no electrolyte separator. A maximum power density of 680 mW cm-2 has been achieved by the NEFC at 550 degreeC. The NEFCs exhibit performances comparable to, and in some cases even better than, those of conventional EBFCs. The design of NEFCs, new material functionalities and device performances may contribute to new fuel cell R&D.
This paper presents the diagnostic results of single polymer electrolyte membrane fuel cell assemblies characterized by polarization curves. Single PEM fuel cell assemblies were investigated through ...accelerated voltage cycling test at different values of relative humidity. The fuel cells are tested at different humidity level. The cells are discussed in this paper with analysis results at different relative humidity at atmospheric pressure. This represents a nearly fully humidified, a moderately humidified, and a low humidified condition, respectively. This technique is useful for diagnosing the main sources of loss in MEA development work, especially for high temperature/low relative humidity operation where several sources of loss are present simultaneously. All the fuel cells showed better performance in terms of limiting current density value through polarization curves when oxygen was fed to the cathode side of each cell instead of air. The results indicate that the performance of the fuel cell could be depressed significantly by decreasing RH from 100 to 33%. Decrease in RH can result in slower electrode kinetics, including electrode reaction and mass diffusion rates, and higher membrane resistance.
•PEM assemblies were investigated through accelerated voltage cycling test.•Best results at different relative humidity at 70 °C fuel cell temperature.•Limiting current density value through polarization curves.•Fuel cell performance is depressed by decreasing RH from 100 to 33%.
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•Activated carbon was synthesized from low cost rice husk by ZnCl2 activation.•Mesoporous structure was given to activated carbon by synthesizing KIT-6 template.•Iron nitrate (III) ...was used as a precursor for imparting magnetic behavior.•The MMAC shows more adsorption for methyl blue and methyl orange dye than AC and MAC.•The MMAC follows Langmuir isotherm for both methyl blue and methyl orange dye.
The novel magnetic mesoporous activated carbon (MMAC) was prepared from activated carbon (AC), produced from rice husk through ZnCl2 chemical activation. Meso-structure was induced via Korea Advanced Institute of Science and Technology-6 (KIT-6) silica formation and magnetic behavior was incorporated by magnetite by wetness impregnation method. KIT-6 silica enhances the porosity and provides a 3D structure to improve the adsorption process. The adsorption of methyl blue (MB) and methyl orange (MO) dyes on MMAC, mesoporous activated carbon (MAC) and AC was investigated and compared. The adsorbents were characterized by SEM, XRD, BET and FTIR analysis techniques. The effect of different process parameters on the adsorption efficiency such as pH of the dye solution, initial dye concentration and dosing of adsorbents were studied. The adsorption efficiency was evaluated by testing aliquot in UV–vis spectroscopy. The experimental data for the MMAC shows that MB followed the Freundlich isotherm while MO was well suited with the Langmuir model. The MMAC removed 82 % MB and 98.5 % MO dye solution in 30 min. The adsorbent was regenerated and reused for MB and MO for 4 cycles without a significant decrease in the adsorption efficiency. The MMAC was found to be the most efficient adsorbent than MAC and AC because of its high surface area and high pore volume. The magnetic behavior of MMAC separates the adsorbent after the adsorption process, making it potential adsorbent for water treatment.
The cobalt doped perovskite cathode material LaNi1-xCoxO3-δ (x = 0.4, 0.6, 0.8) synthesized by cost effective high temperature decomposition is investigated as mixed ionic electronic conductor (MIEC) ...for intermediate temperature solid oxide fuel cell (IT-SOFC). LaNiO3 is known for its high electronic conductivity and to introduce more oxygen vacancies for enhancing its ionic conductivity, Ni at B site is substituted by Co. XRD analysis showed perovskite structure for all samples with no additional phases, which was also confirmed by FTIR results. Microstructure analysis revealed well connected and porous structure for LaNi1-xCoxO3-δ (x = 0.6) compared to other compositions. The elemental analysis using EDX confirmed presence of lanthanum, nickel, and cobalt within all samples. No prominent weight loss was observed during TGA analysis. The highest value of conductivity was obtained for LaNi1-xCoxO3-δ (x = 0.6) due to its porous and networked structure of sub micrometric grains. The superior performance is attained for the cell based on LaNi1-xCoxO3-δ (x = 0.6) cathode with maximum power density of 0.45 Wcm−2 compared to other composition which can be attributed to its well connected and porous structure that caused enhanced electrochemical reaction at triple phase boundary (TPB). It was therefore deduced that LaNi1-xCoxO3-δ (x = 0.6) is promising composition to be used as MIEC cathode for IT-SOFC.
•The efficient cathode for intermediate temperature SOFC.•Achieved biphasic sharp crystalline, hexagonal and monoclinic structure.•A potential electrochemical process in the developed cell.•The significantly better conductivity was achieved.
The perovskite structured cathode Ce0.5Sr0.5Co0.8Fe0.2 O3-δ (CSCF1), Ce0.4Sr0.6Co0.7Fe0.3O3-δ (CSCF2), Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF1) and Ba0.4Sr0.6Co0.7Fe0.3- O3-δ (BSCF2) powders are synthesized ...by sol-gel process using nitrate based powder chemicals for the synthesis of perovskite structured cathode for SOFCs applications. Cerium is used for the first time on A site of perovskite materials and considered to be more promising cathode material for SOFC. The synthesized powders are characterized by XRD, SEM, FT-IR, TGA and conductivity test. XRD results exhibited the formation of perovskite phase. From SEM, it is found that samples are homogeneous and calculated particle size is found as 685 nm, 917 nm, 691 nm and 689 nm for CSCF1, CSCF2, BSCF1 and BSCF2 respectively. In order to study the stability of the prepared materials TGA is conducted at temperature range from 25 °C to 1000 °C. TGA results showed negligible weight loss present in CSCF1. Conductivity values obtained from conductivity test of above said prepared samples were 22.878, 0.078, 0.31 and 0.156 Scm−1 respectively. In particular, the Ce0.5Sr0.5Co0.8Fe0.2O3-δ (CSCF1) showed the maximum conductivity value of 22.878 Scm−1 at 600 °C in air measured by DC 4-probe method, which is much higher as compared to conductivity values of all other prepared samples. The fuel cell performance is carried out by using CSCF1 as cathodes, LiNiCuZn-oxide as anode and SDC-carbonate as electrolyte. By taking all these factors into account, the CSCF1 is found to be the optimal composition, which lead to the peak conductivity and highest power density as compared to other samples.
•Perovskite structured CSCF cathode is prepared by sol-gel method.•High conductivity of the cathode was achieved by the replacement of Cerium with Barium.•XRD proved the perovskite phase.•Performance of the cell is examined by using CSCF as cathodes, LiNiCuZn as anode and SDC-carbonate as electrolyte.
Here we report the synthesis of La and Ba substituted X0.5Sr0.5Co0.8Mn0.2O3 using sol–gel auto-combustion method and their investigation as a low temperature solid oxide fuel cell. Structural ...investigations revealed that La0.5Sr0.5Co0.8Mn0.2O3 (LSCM) crystallized out in rhombohedral perovskite structure while Ba0.5Sr0.5Co0.8Mn0.2O3 (BSCM) has hexagonal perovskite structure. Morphological analysis confirmed the porous structure with uniform distribution of grains. However, agglomeration is decreased when La is replaced with Ba. The existence of all constituent elements as per their stochiometric ratio is evaluated through energy dispersive X-ray spectroscopy. Maximum conductivity value obtained at 600 °C for LSCM and BSCM is 3.51 Scm−1 and 2.26 Scm−1, respectively. In addition, the maximum values of current density and power density achieved by LSCM are 808 mAcm−2 and 277 mWcm−2 while that of BSCM are 663 mAcm−2 and 186 mWcm−2, respectively at low operating temperature of 600 °C. Furthermore, the open circuit voltage (VOC) of LSCM and BSCM based fuel cells is 0.87 V and 0.72 V, respectively which indicates that there are minimal activation losses in the cells. These results showed that the fuel cell based on LSCM cathode has significantly higher values of power density and VOC than that of BSCM based fuel cell. Therefore, LSCM based fuel cell are potential candidate for low temperature futuristic solid-state devices.
•La and Ba based cathode materials for low temperature solid oxide fuel cells.•The good conductivity obtained at 600 °C for LSCM and BSCM is 3.51 Scm−1 and 2.26 Scm−1.•The power density achieved by LSCM are 277 mWcm−2 while that of BSCM are 186 mWcm−2.•LSCM based cell has the best working potential at low temperature with excellent performance.
Sluggish kinetics for oxygen reduction reaction (ORR) is one of the greatest challenges limiting the electrochemical performance of solid oxide fuel cells (SOFCs). Surface modification through ...solution infiltration is recognized as a promising approach to boost the performance of the SOFCs. The conventional infiltration of electrocatalyst in porous scaffold results in discrete particles of active catalyst. However, in this study, we report a novel technique to produce the nano-tailored film of Sm0.5Sr0.5CO3-δ (SSC) active catalyst on to La0.6Sr0.4CoO3-δ (LSC) cathode of SOFC through controlling the drying rate during the infiltration process which resulted in a continous film like coating of SSC. The SOFC with LSC cathode containing SSC film-like nanostructure showed a two-fold performance increment and an excellent durability compared to the LSC cathode prepared through conventional methods. The higher performance of the film-like nanostructured LSC-SSC cathode is attributed to the remarkable reduction in the area-specific ohmic and polarization resistance due to the extension of cathode reaction sites and shorter diffusion lengths, thus, facilitating the ORR.
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•SSC coated LSC cathodes were prepared by single-step infiltration method.•Various SSC morphologies were prepared by controlling the infiltration drying rate.•The film-like infiltrated SSC enhances electrochemical performance by two times.•The film-like infiltrated SSC shows the excellent stability for 300 h.
•Efficient cathode LiMn2O4 with Asphalt and Bituminous were prepared to be tested as in (LIB’s).•High porosity and large surface area of extracted carbon proven promising choice for the dendrites ...minimization.•Reasonably good LIB’s capacitance of bituminous composite was found as Csp 586 Fg−1over asphalt Csp 517 Fg−1 .•This novel composite renders less ohmic resistance by resaonably improving leakage current of LIB’s.
Lithium ion battery is a promising energy storage device because of high energy and power densities. This study aims at the fabrication of a low-cost efficient cathode material for the enhanced battery performance with reasonably higher power and energy density over its contemporary cathode materials. In this regard, LiMn2O4/asphalt and LiMn2O4/bituminous coal based composite materials were synthesized employing co-precipitation and sol–gel approaches and evaluated as electrode material. Results revealed that LiMn2O4/bituminous coal composite, owing to remarkably high specific capacitance as Csp 586 Fg−1 at a scan rate 5 mVs−1, could be a promising economical cathode material for the energy density enhancement of a battery in comparison to LiMn2O4/asphalt composite.
•The combination of Fe and Mn significantly enhances the ceria catalytic activity.•The inclusion of Mn3+ and Fe3+ ions into CeO2 created additional oxygen vacancies.•The OCV is (0.98 V and power ...density of (335 mW cm-2 is obtained at 550 °C.•The XRD shows the composite cathode has a multi-phase structure.
In this study, Fe-Mn co-doped ceria Fe0.25Mn0.00Ce0.75O2-δ (FMDC1), Fe0.23Mn0.02Ce0.75O2-δ (FMDC2), Fe0.21Mn0.04Ce0.75O2-δ (FMDC3), and Fe0.19Mn0.06Ce0.75O2-δ (FMDC4) powders are synthesized by sol gel method and evaluated as cathode materials for intermediate temperature solid oxide fuel cell (IT-SOFC). The combination of Fe and Mn significantly enhanced the ceria catalytic activity and oxygen kinetics for redox-based reactions. The effects of the co-doping mechanism on the phase composition, optical behavior, and electrochemical performance are mainly investigated. The prepared samples are characterized by XRD, SEM, FTIR, UV–vis, and conductivity tests. X-ray diffraction analysis revealed well-developed crystallinity with a single phase cubic structure of synthesized cathode material. SEM depicted the highly porous facet for Fe0.19Mn0.06Ce0.75O2-δ (FMDC4) resulted in the large triple-phase boundaries for the reduction of ambient air. The inclusion of Mn3+and Fe3+ ions into CeO2 network created additional oxygen vacancies (Ov) and simultaneously reduced the optical band gap energy from 2.81 eV for FMDC1 (x = 0.00) to 2.54 eV for FMDC4 (x = 0.06). Among the four samples, FMDC4 possessed the highest electrical conductivity (∼0.89 Scm−1) at 650 °C and corresponding low activation energy of ∼0.301 eV, which lead to good catalytic activity with an enhanced electrochemical performance of the SOFC system. The open-circuit voltage (OCV) attained the value of ∼0.98 V, maximum power density of ∼335 mW cm−2 is obtained at 550 °C, which is comparable to previously reported electrodes. The results suggested that the combination of Fe and Mn into ceria can be used as an effective catalytic promoter for oxygen reduction reactions (ORR), and the composition of FMDC4 resulted in the peak conductivity, short term stability and highest power density as compared to other synthesized samples.
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•LSCF-SCDC nanocomposite has been developed as a membrane for SIMFC fabrication.•The SIMFC exhibited maximum power density of 814mWcm−2 at 550°C.•The SIMFC presented better ...performance than that of conventional FC technology.•The Schottky junction effect was proposed to avoid the short circuiting problem.
A novel semiconductor-ionic La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF)-Sm/Ca co-doped CeO2 (SCDC) nanocomposite has been developed as a membrane, which is sandwiched between two layers of Ni0.8Co0.15Al0.05Li-oxide (NCAL) to construct semiconductor-ion membrane fuel cell (SIMFC). Such a device presented an open circuit voltage (OCV) above 1.0V and maximum power density of 814mWcm−2 at 550°C, which is much higher than 0.84V and 300mWcm−2 for the fuel cell using the SCDC membrane. Moreover, the SIMFC has a relatively promising long-term stability, the voltage can maintain at 0.966V for 60hours without degradation during the fuel cells operation and the open-circuit voltage (OCV) can return to 1.06V after long-term fuel cell operation. The introduction of LSCF electronic conductor into the membrane did not cause any short circuit but brought significant enhancement of fuel cell performances. The Schottky junction is proposed to prevent the internal electrons passing thus avoiding the device short circuiting problem.
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