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A structural battery is a multifunctional battery that can carry a load while storing energy. Structural batteries have been a cutting-edge research focus in the last decade and are mainly based on polyacrylonitrile (PAN)-carbon fibers (CFs). In this work, positive electrodes based on PAN-carbon fibers were manufactured with powder impregnation (siphon impregnation) technique using a water-based slurry containing lithium iron phosphate (LFP) as the active electrode material and the water-soluble binder polyethylene glycol (PEG). Different coating compositions, electrode-drying temperatures, and coating parameters were investigated to optimize the coating uniformity and the electrochemical performances. Scanning electron microscopy results showed that the electrode materials coat the CFs uniformly, conformably, and individually. Electrochemical characterization of pouch cells shows that the electrodes containing 6 wt% PEG dried at 140 degrees C have the best battery performance, delivering a first discharge capacity of 151 mAh g-1 and capacity retention higher than 80% after 100 cycles. Moreover, excellent capacity reversibility was achieved when the electrodes were cycled at multiple C-rates attesting to their stability. The results demonstrate that CFs perform excellently as current collectors in positive electrodes., QC 20230824

Using stainless steel as material for bipolar plates (BPPs) in proton exchange membrane fuel cells (PEMFCs) carries a perceived risk of corrosion and subsequent metal ion contamination of the membrane electrode as-sembly (MEA). However, assessments in literature on this hazard to PEMFC systems have been based on ex-situ corrosion studies, where general assumptions made on the BPP environment might not be a correct simulation of real on-site conditions. In this contribution, uncoated BPPs from stainless steel grades 304 L, 316 L and 904 L were subjected to in-situ hybrid endurance/stress testing to simulate realistic conditions in operating fuel cell systems and re-evaluate the need of additional corrosion protection. A post analysis of the plates showed no signs of surface dissolution on any of the tested samples and the concentration of iron in the MEA averaged 7 to 10 ppm for uncoated samples and 7 to 11 ppm for coated and graphitic reference tests, displaying a negligible amount of trace metals compared to critical thresholds found in literature. Contact resistance values were stable for all samples and observable changes in cell performance and voltage degradation was confirmed to be un-related to the presence of uncoated bipolar plates. The combined effects of decoupling of bipolar plate surface potentials from electrode potentials and operational control of stable gas flow compositions to sustain stainless steel surface passivation, were identified as explanation for the experimentally observed corrosion resistance of uncoated stainless steel plates in PEMFCs., QC 20230904

The integration of proton exchange membrane fuel cells (PEMFCs) in heavy-duty vehicles would be facilitated if operating temperatures above 100 degrees C were possible. In this work, the effect of temperature in the intermediate range of 80-120 degrees C is investigated for a commercial membrane electrode assembly (MEA) through polarization curves and electrochemical impedance spectroscopy. The importance of oxygen partial pressure on voltage is systematically studied by decoupling it from humidity and temperature. The results show that adequate oper-ation at intermediate temperature is achievable if the oxygen partial pressure is sufficient. Although the cathode kinetics is faster with rising temperatures, the voltage gain is counteracted by the decreasing equilibrium po-tential. At intermediate temperature, the water transport is enhanced, levelling out the relative humidity dif-ference between anode and cathode. However, ionic conductivity in the polymer can become limiting at high currents, due to a smaller relative humidity increase at these temperatures. To conclude, a higher operating temperature does not inherently cause a decrease in obtained current density. Rather, the difficulty to simul-taneously have sufficient oxygen partial pressure and high relative humidity causes limitations within the cathode that to some extent can be solved by pressurizing the cell., QC 20230620

The bipolar plate (BPP) is a component with vast cost-reduction potential in proton exchange membrane fuel cells (PEMFCs). Apart from mechanical and heat transfer requirements, the most desired BPP properties are high corrosion and low electrical contact resistance. In this study we confirm that due to ionic decoupling between BPPs and electrodes, the surface potentials of the BPPs remain stable even at varying operation loads. These mild potentials, in combination with low metal-ion leeching due to passive-transpassive-passive dissolution in stainless steels, suggest that low-cost carbon-coated stainless steel can readily be used as a BPP in PEMFCs. To prove this, single-fuel cell tests were carried out under realistic driving conditions, including electrochemical analysis, in-situ contact-resistance measurements, and post-mortem investigation of the membrane electrode assembly (MEA) by inductively coupled plasma trace-metal analysis, combined with electron microscopy and Auger spectroscopy of the BPPs. The results show that due to the ionic decoupling, conditions at the BPP surfaces are much less corrosive than previously thought. Furthermore, carbon-coated stainless-steel BPPs prove to be unaffected by global hydrogen starvation, which causes severe MEA degradation independent of the presence or absence of BPPs., QC 20220120

The study of the catalytic activity in a fuel cell is challenging, as mass transport, gas crossover and the counterelectrode are generally interfering. In this study, a Pt electrode consisting of a thin film deposited on the gasdiffusion layer was employed to study the oxygen reduction reaction (ORR) in an operating Anion Exchange Membrane Fuel Cell (AEMFC). The 2D Pt electrode was assembled together with a conventional porous Pt/Ccounter electrode and an extra Pt/C layer and membrane to reduce the H2 crossover. Polarization curves atdifferent O2 partial pressures were recorded and the resulting reproducible ORR activities were normalized withrespect to the active surface area (ECSA), obtained by CO stripping. As expected, decreasing the O2 partialpressure results in a negative shift in open circuit voltage (OCV), cell voltage and maximum attainable currentdensity. For cell voltages above 0.8 V a fairly constant Tafel slope of 60 mV dec−1 was recorded but at lowervoltages the slope increases rapidly. The observed Tafel slope can be explained by a theoretical model with anassociative mechanism where charge- and proton-transfer steps are decoupled, and the proton transfer is the rate-determining step. A reaction order of 1 with respect to O2 was obtained at 0.65 V which corresponds well withthe mechanism suggested above. Based on the obtained catalyst activities, the electrode performance is com­parable to good porous electrodes found in the field. The methodology presented in this study is expected to beuseful in future kinetic studies of other catalysts for AEMFC., QC 20221129

Alloying platinum is an approach to increase the oxygen reduction reaction (ORR) activity and at the same time reduce the amount of precious platinum catalyst in proton exchange membrane fuel cells (PEMFC). In this work the cathode activity of thin films of rare earth metals (REM) alloys, Pt 3 Y, Pt 5 Gd and Pt 5 Tb, produced by sputter deposition onto gas diffusion layers, are evaluated in a fuel cell by means of polarization curves in O 2 /H 2 , and cyclic- and CO-stripping voltammetry in N 2 /5% H 2 . Prior to evaluation, the model electrodes were acid-treated to obtain a Pt skin covering the PtREM alloy bulk, as was revealed by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The core shell alloys of Pt 3 Y and Pt 5 Gd catalysts show a specific activity enhancement at 0.9 V of 2.5 times compared to pure Pt. The slightly lower enhancement factor of 2.0 for Pt 5 Tb is concluded to be due to leaching of the REM, that resulted in a thicker, and subsequently less strained, Pt overlayer. The high activity, combined with the minor changes in surface composition, achieved in the fuel cell environment shows that PtREM core shell catalysts are promising for the cathode reaction in PEMFC., QC 20210916

Trace-metal contamination poses a threat to performance and stability of proton exchange membrane fuel cells (PEMFCs). In this study the source of origin and degree of metal dissolution from carbon-coated 316L bipolar plates (BPPs) are evaluated after a long-term PEMFC test run under conditions resembling a real-life automotive application. Despite intact carbon-coating, metal dissolution occurs from uncoated oxycarbide stains on the plates? surface. Which correlates with post-mortem detection of chromium, iron and nickel in the membrane electrode assembly. The rate of cell voltage decrease throughout the high current operations is found to be twice as high in the presence of metal ions. Metal dissolution can be correlated with transients in cell voltage during dynamic current load cycling as a result of temporary global fuel starvation. The observed difference in metal dissolution on the anode and cathode BPP indicates weak galvanic coupling between the bipolar plate(s) and the electrode layer(s). ? 2020 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/)., QC 20210531

There is a strong need to develop purification methods for textile industrial wastewater containing toxic azo dyes. The reductive cleavage of azo dyes can be made by anaerobic bacteria, but the products of aromatic amines require an aerobic process. In this study a novel bacterial dye degrading consortium (DDC) of five isolated strains identified with 16S rRNA sequence: Proteus mirabilis (KR732288), Bacillus anthracis (KR732289), Enterobacter hormaechei (KR732290), Pseudomonas aeruginosa (KR732293) and Serratia rubidaea (KR732296) were used to aerobically decompose metabolite 2-aminobenxenesulfonic acid (2-ABS), as a model compound. The effect of three variables: temperature (28-42 degrees C), pH (5.0-8.0) and initial concentration of 2-ABS (5-40 ppm) was investigated in terms of degradation and chemical oxygen demand (COD) removal. Central composite design matrixand response surface methodology (RSM) were used for experimental design to evaluate theinteraction of the three process variables. The results show that up to 95% degradation and COD 90% removal are possible at optimal values of 32.4 ppm 2-ABS, pH 6.6 and a temperature of 35.7 degrees C. The theoretical response variables predicted by the developed RSM model was supported the experimental results. The optimized degradation of 2-ABS and COD removal were further confirmed by UV-HPLC analysis., QC 20200713