Papers by Keyword: Fuel Cell

Abstract: Conductive polymer composite materials for polymer electrolyte membrane fuel cells bipolar plates have been successfully prepared from renewable plant biomass sources and copolymers of tetrafluoroethylene with vinylidenefluoride. The composites are based on various conductive fillers (natural, oxidized and colloidal graphite’s) and polymer binder (the 5-HMF synthesis by-product or fluoroplastic). The influences of type and content of binder and type of conductive filler on the mechanical properties and conductivity were investigated. Conductivity of the composites decreases with increasing of polymer content, but its mechanical properties changes inversely. Composite based on 5-HMF by-products (content 30 wt.%) and colloidal graphite as a filler meets the DOE requirements for a mechanical strength. Flexural and compressive strengths were 25 and 32 MPa, respectively. Composites based on fluoroplastic 32 (content 30 wt.%) and fluoroplastic 42 (content 20 wt.%) with colloidal graphite as a filler and fluoroplastic 42 (content 20 wt.%) with nature graphite have flexural strength values close to the target value of DOE and amounted to 24, 17 and 19 MPa, respectively. Interfacial contact resistance depends to a greater extent on the nature of the filler and is maximum for composites based on natural graphite. Composites based on fluoroplastic 42 at any filler content correspond to the requirements DOE ≤ 0.01 ohm∙cm². Composite based on 5-HMF synthesis by-product (resin) and fluoroplastic with conductive filler (colloidal graphite) shows a great potential application as bipolar plates for PEMFCs.

Abstract: Metalloporphyrin-based nanostructures were fabricated on 3-aminopropylmethoxysilane-modified indium tin oxide (ITO) surface. UV-visible spectroscopy and cyclic voltammetry are used for investigating electronic absorption spectra and catalytic activity in oxygen reduction reactions as alternative cathode electrochemical catalysts for polymer electrolyte membrane fuel cells (PEMFCs). Using of 5,10,15,20-tetrakis-(4-amiophenyl)-porphyrin-Co (II) as a building block and 1,4-phenylene diisocyanate as a linker, the mixed toluene/chloroform solution-based layer-by-layer process can produce linear growth of 5,10,15,20-tetrakis-(4-amiophenyl)-porphyrin-Co (II) up to 30 layers through urea bonds. The vacuum thermal annealing process demonstrated the improvement of catalytic activity in oxygen reduction reaction.

Abstract: A highly active Platinum Group Metal (PGM) and non-PGM electrocatalysts with thermally extruded nanotubes have been prepared for Proton Exchange Membrane (PEM) fuel cell by sintering Nickel zeolitic imidazole framework (Ni-ZIF). Preeminent electro-catalytic activities have been observed through single fuel cell tests and rotating disk electrode (RDE). This study involves the comparison of Oxygen Reduction Reaction (ORR) activities and fuel cell (FC) test station performance of two catalyst Nickel and Platinum mixed Nickel nanotubes (Ni NT, Ni/Pt NT) respectively. The acidic cells with corresponding Ni and Ni/Pt catalysts delivers peak power densities of 325 mWcm^-2 and 455 mWcm^-2 at 75 °C inside fuel cell. Our results indicate that, the synthesized Nickel nanotubes has profound effect on catalytic performance of both PGM and non-PGM electro catalysts.

Abstract: Conductive polymer composite materials for polymer electrolyte membrane fuel cells bipolar plates have been successfully prepared from renewable plant biomass sources. The composites are based on various conductive fillers (natural, oxidized and colloidal graphites) and the 5-hydroxymethylfurfural synthesis by-product resin that consists of complex furanic oligomers and polymers. The influences of the resin content and type of conductive filler were investigated. The conductivity of the composite are decreased with increasing resin content, but its mechanical properties are improve. A sample with a resin content of 10 wt. % and colloidal graphite filler have showed the optimal balance between electrical conductivity and mechanical properties. The interfacial contacting resistance, flexural and compressive strength of the composite were 0.035 ohm•cm2, 18.4 MPa and 21.4 MPa, respectively. Composite based on 5-hydroxymethylfurfural synthesis by-product resin and conductive filler (colloidal graphite) are showed a great potential application as bipolar plates for polymer electrolyte membrane fuel cells.

Abstract: A highly corrosion resistant and conductive polymer coating for polymer electrolyte membrane fuel cells bipolar plates have been successfully prepared from renewable plant biomass sources. The coating is based on the 5-hydroxymethylfurfural synthesis by-product resin that consists of complex furanic oligomers and polymers. The corrosion resistance and conductivity of coated titanium plates have been studied. As-prepared coated Ti samples are shown 0.083 μA/cm² and 0.32 μA/cm² corrosion current in the simulated PEMFCs cathode and anode environment respectively. In addition, the polymer coating are reduced the interfacial contact resistance of bare titanium up to 40 %. The Ti plates coated with by-products of 5-HMF synthesis are shown a great potential application as bipolar plates for PEMFCs.

Abstract: In this work, an anode-supported button cell was fabricated with compositionally gradient (CG) NiO-BaCe_0.54Zr_0.36Y_0.1O_2.95 (NiO-BCZY) anode functional layer (AFL). The button cell has a configuration of NiO-BCZY (50:50) | NiO-BCZY (30:70) | NiO-BCZY (10:90) | BCZY | LSCF. All powder materials were synthesized using a sol-gel method. Firstly, NiO-BCZY anode substrate was fabricated using dry-pressing method. Next, NiO-BCZY CG-AFL and BCZY electrolyte thin film were spin-coated on the anode substrate and lastly the La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) cathode was spin-coated on the electrolyte thin film. The microstructure of the fabricated button cell with good adhesion between all the layers, thin and dense electrolyte layer, and gradient increase in density of materials from anode substrate to electrolyte were observed using Scanning Electron Microscopy (SEM). Cell’s performance in terms of resistivity was evaluated using Electrochemical Impedance Spectroscopy (EIS) and conductivity meter using four-point probe method. Values of ohmic (R_o) and polarization resistance (R_p) of the cell are 7.3 and 2.4 Ωcm² at 700 °C, respectively. The lower resistance values obtained compared to our previous work on a conventional 3-layers BCZY-based single button cell (R_o = 9.6 and R_p = 7.8 Ωcm² at 700 °C) confirmed the functionality of GC-AFL in enhancing the cell’s performance. This preliminary result shows that simple deposition technique of CG-AFL plays a significant role in the optimization of PCFC button cell designs and electrochemical performance.

Abstract: Application of multi-pulse multilevel inverters is considered in this paper for distributed generation. A five-level twelve-pulse neutral point clamped inverter has been combined with a proton exchange membrane fuel cell in order to investigate load following characteristics of the fuel cell. The fuel cell implemented with a three-phase multi-pulse multilevel inverter is adept of delivering single-phase and three-phase loads both in islanded and grid-connected approach. Changes in power demand from no-load to full-load (120 kW) have been applied to study the characteristics of the system from the perspective of how it can follow the load changes in load demand. It has been observed that the fuel cell model is adept of following power request as per requirement; however, there is a response time of few seconds, because the reformer for the fuel cell requires time to generate fuel and the fuel cell requires time for chemical reactions to take place in it. Implementations of six-pulse and twelve-pulse five-level neutral point clamped and flying capacitor inverters show that total harmonic distortions for six-pulse and twelve-pulse five-level neutral point clamped inverters to be 1.066219% and 0.406149% respectively as compared to 2.466889% and 1.5104075% for flying capacitor inverters. It has been observed that with twelve-pulse neutral point clamped inverter, the output voltage waveform is smoother and close to sinewave. The results of the research work is presented with analyses to validate that multi-pulse multilevel neutral point clamped inverter is a better way out for the fuel cell power generation model as this type of inverters produces smoother waveforms to improve power quality with lower harmonics.

Abstract: Renewable energy sources, such as photovoltaic, fuel cell and wind energy are becoming a sustainable alternative to non-renewable sources like fossil fuel. However, to integrate these energies into the grid, power electronic converters plays major role due to their power conditioning capability, reliability and effectiveness. In this paper, design, modeling and analysis of a DC-DC boost converter with robust controlling technique, fuzzy sliding mode controlling strategy has been developed and a brief comparison has been performed with a sliding mode controller and a clasical PID controller which employed both current and a voltage control loop. The system is designed to achieve a fast dynamic response, zero steady-state error, and satisfactory stability. To realize that a detailed mathematical derivation of sliding mode fuzzy logic controller and a linearized small signal model of the power electronic converter around its DC steady state operating point is performed. Finally, in order to evaluate the designed system, a software simulation based on MATLAB/ Simulink environment is developed and results of the simulation shows the effectiveness of the proposed techniques.

Abstract: An increasing number of attention is being paid to perovskite oxides due to their relatively low prices and comparable ability in being an alternative choice to replace high-priced metal catalyst in many fields. In this work, a group of Ti/Nb co-doped SrCoO_3-δ-based perovskite oxides SrTi_xNb_0.2-xCo_0.8O_3-δ (x=0, 0.05, 0.1, 0.15, 0.175, 0.2) were synthesized and measured as candidates for oxygen evolution reaction (OER). Among all the perovskite samples, SrTi_xNb_0.2-xCo_0.8O_3-δ (x=0.175, STNC-4) displayed the lowest OER overpotential of 0.4 V and the lowest Tafel plots as well as fastest charge transfer ability. This catalyst also revealed a great durability in alkaline solution.

Abstract: In a quest for a cleaner planet and to have alternative forms of energy generation apart from the fossil-based power supply, fuel cell technology has emerged as an alternative energy source for usage across all economic sectors. The application of this age-old technology is found in alkaline (AFC), molten carbonate (MCFC), phosphoric acid (PAFC), polymer electrolyte membrane (PEMFC) and solid oxide (SOFC) fuel cells. These fuel cells are named based on the type of electrolyte employed in their applications and the fuel of choice for energy generation is hydrogen. This fuel can be used in its pure form or extracted from other sources such as methanol, water and syngas. Ammonia in its liquefied and gaseous forms may be used as a non-carbonaceous fuel for the hydrogen source in some of these fuel cell technologies due to its safety, lower price, ease of storage and transportation. In this review, all the fuel cells will be investigated in their capability of using ammonia as a direct fuel. The role of earth abundant metal catalysts in comparison to TiO₂ was evaluated in terms of molecular orbital theory and in the decomposition of organic compounds and other material into nitrogen and hydrogen products under the visible light radiation. The p-orbital participation in earth abundant metals or metal oxides doping, emerged as a strong contribution to bandgap attenuation.