Performance Evaluation for Ultra-Lightweight Epoxy-Based Bipolar Plate Production with Cycle Time Reduction of Reactive Molding Process.

The commercial viability of fuel cells for vehicle application has been examined in the context of lightweight material options, as well as in combination with improvements in fuel cell powertrain. Investigation into ultra-lightweight bipolar plates (BPs), the main component in terms of the weight effect, is of great importance to enhance energy efficiency. This research aims to fabricate a layered carbon fiber/epoxy composite structure for BPs. Two types of carbon fillers (COOH-MWCNT and COOH-GNP) reinforced with woven carbon fiber sheets (WCFS) have been utilized. The conceptual idea is to reduce molding cycle time by improving the structural, electrical, and mechanical properties of BPs. Reducing the reactive molding cycle time is required for commercial production possibility. The desired crosslink density of 97%, observed at reactive molding time, was reduced by 83% at 140 °C processing temperature. The as-fabricated BPs demonstrate excellent electrical conductivity and mechanical strength that achieved the DOE standard. Under actual fuel cell operation, the as-fabricated BPs show superior performance to commercial furan-based composite BPs in terms of the cell potential and maximum power. This research demonstrates the practical and straightforward way to produce high-performance and reliable BPs with a rapid production rate for actual PEMFC utilization.

Hydrogen Flow Controller Applied to Driving Behavior Observation of Hydrogen Fuel Cell Performance Test.

Fuel cell performance tests for automotive applications include static and dynamic tests, and the dynamic load test is typically carried out to investigate the cell operating performance related to driving behavior in the particular use of fuel cell electric vehicles. The automatic hydrogen flow controller, utilized to regulate the hydrogen flow as a function of time, is one of the imperative apparatuses applied for the dynamic test. The driving behavior generally consists of rapid load fluctuations, several loads running at idle, full power, overload circumstances, start-stop repeats, and cold starting, and these dynamic variations are directly related to the power required for propelling a vehicle and the demand for hydrogen volume fluctuation throughout time. The desired automatic hydrogen flow controller was designed and manufactured for the dynamic performance test via the driving simulation protocol of a heavy-duty vehicle. The main experimental activities were performed to observe the responsibility and accuracy of the invented controller. The relation between the reliability of using the automatic hydrogen flow controller and the performance improvement of fuel cell operation was studied to gain ideas for further fuel cell modification. The hydrogen flow rates controlled by the created flow controller presented a data tolerance of approximately 0.84% which was not significantly different from the theoretical figure based on T-test analysis. The controller reacted to variations in flow rates in as little as 1-2 s, which was acceptable for the dynamic test. Regarding the performance enhancement, this automatic hydrogen flow controller assisted a single cell to generate 16% more power and 33% more energy at 45 mA as a minimum current demand in comparison with the results obtained from a test system using a traditional hydrogen controller with a constant flow rate.

Fabrication of Bipolar Plates from Thermoplastic Elastomer Composites for Vanadium Redox Flow Battery.

A vanadium redox flow battery (VRFB) is a promising large-scale energy storage device, due to its safety, durability, and scalability. The utilization of bipolar plates (BPs), made of thermoplastic vulcanizates (TPVs), synthetic graphite, woven-carbon-fiber fabric (WCFF), and a very thin pyrolytic graphite sheet (GS), is investigated in this study. To boost volumetric electrical conductivity, WCFF was introduced into the TPV composite, and the plate was covered with GS to increase surface electrical conductivity. Created composite BPs acquire the desired electrical conductivity, mechanical strength, and deformation characteristics. Those properties were assessed by a series of characterization experiments, and the morphology was examined using an optical microscope, a scanning electron microscope, and atomic force microscopy. Electrochemical testing was used to confirm the possibility of using the suggested BP in a working VRFB. The laminated BP was utilized in a flow cell to electrolytically convert V(IV) to V(V) and V(II), which achieved comparable results to a commercial graphite bipolar plate. Following these experiments, the laminated bipolar plates' surfaces were examined using X-ray photoelectron spectroscopy, and no evidence of corrosion was found, indicating good durability in the hostile acidic environment.

Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming.

Megapores with spherical-like cells connected through windows and high porosities make up catalyst supports in the form of ceramic foams. These characteristics provide significant benefits for catalytic processes that are limited by mass or heat transport. This study focuses on the manufacture of ceramic foam using a polymeric sponge replica process and polymer foams as a template for catalyst supports, which are industrial waste from the packaging sector. To make ceramic foam catalysts, they were dipped in a catalyst solution, followed by a breakdown stage and a sintering process. Experiments focused on determinants that affect the desired characteristics of ceramic foams, such as the types of polymer foams that affect foam morphology, the rheology of catalyst solution that affects catalyst dispersion, and the polymer decomposition rate that affects catalytic performance during dry reforming of the methane process. The cell architectures of polyurethane and polyvinyl alcohol foams are attractive for catalyst support preparation because they have 98-99% porosity and typical cell sizes of 200 and 50 µm, respectively. The polyurethane performance was superior to the performance of polyvinyl alcohol in terms of higher porosity and better catalytic-solution absorption offering high catalyst active areas. The catalyst prepared from concentrated 10 wt % Ni/Al2O3-MgO (10NAM) slurry had the highest surface area (59.18 m2/g) and the highest metal oxide dispersion (5.65%). These results are relevant to the flow behavior of catalyst slurry which plays a key role in coating the catalyst gel on the polymer template. The thermal decomposition rate used to remove the polymer template from the catalyst structure is proportional to the ceramic foam structure (catalyst support structure). The slow decomposition rate bent and fractured foam-cell struts more than the faster rate. On the other hand, achieving good catalyst dispersion on catalyst supports necessitated a high sintering rate. When sintering was adjusted at a high sintering rate, the metal-particle dispersion was relatively high, around 7.44%, and the surface area of ceramic foam catalysts was 64.61 m2/g. Finally, the catalytic behavior toward hydrogen production through the dry reforming of methane using a fixed-bed reactor was evaluated under certain operating conditions.

The observation of supercapacitor effects on PEMFC-supercapacitor hybridization performance through voltage degradation and electrochemical processes.

In the cities in the future, seeing electric vehicles on the roads will be as ordinary an occurrence as seeing internal combustion engine cars today. Electric vehicles can greatly benefit from utilizing polymer electrolyte membrane fuel cells (PEMFCs) because they provide higher efficiency (40-50%) and are more environmentally friendly. However, there are some major drawbacks to using PEMFCs as electrical sources in vehicles; these are energy balance and management issues that must be addressed to meet vehicle power and energy requirements. Therefore, it seems that hybridizing PEMFCs with energy storage devices, such as supercapacitors (SCs), would be an efficient solution to address these drawbacks in order to accommodate driving behaviors such as dynamic loads. The goal of this research is, therefore, to demonstrate the use of a PEMFC-SC direct hybridization configuration with a dynamic stress test by simulating driving behavior in urban areas such as Bangkok. This research presents substantial advantages in energy management and voltage and material degradation. In order to achieve this objective, a quasi-static stress profile, including stationary conditions, load variations, and start-stop conditions, was specifically created for PEMFC-SC direct hybridization systems with 840 hours of operating duration. The performance, durability, and reliability of this system were investigated via polarization curves, hysteresis loops, and voltage degradation rates. Then, experimental results were compared to the degradation of the cell components. Any degradation in material components was observed through electrochemical impedance spectroscopy (EIS) and morphology studies. The characterization of materials in the PEMFC-SC direct hybridization systems via chemical and electrochemical analyses is an important approach in material invention and modification for the new generation of PEMFCs. This work strives to pave the way for PEMFC hybridization development to achieve effective commercialization.

Studies on surface modification of polypropylene composite bipolar plates using an electroless deposition technique.

A direct methanol fuel cell (DMFC) is predominantly noticeable because it can convert chemical energy directly into electrical energy with higher energy conversion efficiency (∼65%) compared to the efficiency of traditional combustion engines (40%) and with lower emissions. Henceforth, it is one of the new electrical generators that is becoming an important source of cleaner power in modern life. One of the key obstacles in designing and assembling the DMFC is contact resistance between interfaces of fuel cell components. A major source of the contact resistance in the DMFC arises from the contact between gas diffusion layers (GDLs) and the bipolar plates (BPs). A poor interface contact decreases the actual contact area, leading to an electrical voltage drop across these interfaces. Decreasing surface resistivity of BPs is one of the major approaches to reduce contact resistance in fuel cells. Present-day methods use a polypropylene composite as BPs to replace metallic or graphite BPs to reduce the overall weight of the DMFC stack. Unfortunately, polymeric composites typically provide higher surface resistance than the other BPs do. Coating copper on polypropylene composite plates was strategically manipulated by an electroless deposition (ELD) technique to decrease surface resistance. The coating process consists of pretreatment, adhesion improvement, and electroless deposition. Prior to ELD, the surfaces of the composite plates were treated by plasma treatment and then silanization was conducted using N-3-(trimetylpropylsilyl)diethylenetriamine (TMS) to improve adhesion. Palladium(ii) chloride (PdCl2) was used as a catalyst for the ELD process. Successful modification of the surfaces was confirmed by morphology investigation via scanning electron microscopy, diagnoses of chemical surface characteristics using ATR-Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), physical surface characterizations with a contact angle measurement, electrical conductivity measurements, and surface adhesion test, while also observing corrosion behavior. In order to complete a viability study of using modified copper-coated BP for the DMFC, an in situ cell performance test was conducted. The results of the experiments pave the way for a feasible modification of the BP surfaces to be considered as suitable BPs for usage in fuel cells.