PEM vs. AEM fuel cells fed with hydrogen or hydrogen-rich alcohols: Physico-electrochemical phenomena and performance characteristics

This review focuses on: (a) describing the physicoelectrochemical transport phenomena in alkaline Anion Exchange Membrane Fuel Cells (AEMFCs) and acidic Proton Exchange Membrane Fuel Cells (PEMFCs) fed with hydrogen or hydrogen-rich alcohols, such as e.g. ethanol, methanol, and (b) reporting alkaline AEMFC vs. acidic PEMFC polarisation performance characteristics such as, maximum area-specific and mass-specific power densities. Copyright © 2013 Delta Energy and Environment

Performance modeling of an alkaline anion exchange membrane-based direct glucose fuel cell

An AEM-based DGFC performance model is developed and compared against literature experimental results. Performance predictions for different anode and PtAg/C cathode catalysts, using the 1-D flux-based model, are reported. Copyright © 2013 Delta Energy and Environment

The effect of the parasitic current on the direct ethanol PEM fuel cell operation

In the present work the effect of the parasitic or leakage current, I, which is the result of the ethanol crossover through the polymer electrolyte membrane (PEM) from the anode to the cathode side of the cell, on both the cathode activation overpotential and the fuel cell operation is investigated. A one-dimensional (I-D), isothermal mathematical model is developed in order to describe the operation of a Direct Ethanol PEM Fuel Cell (DE-PEMFC) in steady state. The equations used describe the mass transport of both ethanol and humidified oxygen at the anode and the cathode compartment of the cell respectively. The mathematical model is validated against experimental data and a relatively good agreement between the model predictions and the experimental results is found. The direct correlation that exists between the ethanol crossover rate and the parasitic current formation is graphically depicted. Moreover, when the parasitic current is enabled and disabled, the calculation of the cathode activation overpotential shows that the mixed overpotential for a DE-PEMFC poses a serious problem hindering the fuel cell operation. According to the model results, the parasitic current is greater at low current density values due to the greater amounts of the crossovered ethanol. Finally, the effect of both the oxygen feed concentration and the parasitic current formation on the fuel cell operation is also presented and discussed. (c) 2008 Elsevier B.V. All rights reserved

BaCeO3: Materials development, properties and application

The characteristic of a number of oxide materials, which include BaCeO3-systems, is their ability to show the proton conductivity along with oxygen-ion conductivity. Such atypical behavior for other oxides attracts great interest in theoretical and experimental solid state electrochemistry. The present review aims at: (a) summarizing the evolution of new functional BaCeO3-based materials with respect to their properties, and properties' optimization (importance of ceramics' technology preparation, structural and thermodynamic stability of materials, enhanced ionic conductivity of electrolytes with low electronic contribution, thermal and chemical compatibility with other oxide components), and (b) examining the possibility of their application in various solid oxide electrochemical devices. (C) 2013 Elsevier Ltd. All rights reserved

A model-based parametric analysis of a direct ethanol polymer electrolyte membrane fuel cell performance

In the present work, a model-based parametric analysis of the performance of a direct ethanol polymer electrolyte membrane fuel cell (DE-PEMFC) is conducted with the purpose to investigate the effect of several parameters on the cell's operation. The analysis is based on a previously validated one-dimensional mathematical model that describes the operation of a DE-PEMFC in steady state. More precisely, the effect of several operational and structural parameters on (i) the ethanol crossover rate from the anode to the cathode side of the cell, (ii) the parasitic current generation (mixed potential formation) and (iii) the total cell performance is investigated. According to the model predictions it was found that the increase of the ethanol feed concentration leads to higher ethanol crossover rates, higher parasitic currents and higher mixed potential values resulting in the decrease of the cell's power density. However there is an optimum ethanol feed concentration (approximately 1.0 mol L(-1)) for which the cell power density reaches its highest value. The platinum (Pt) loading of the anode and the cathode catalytic layers affects strongly the cell performance. Higher values of Pt loading of the catalytic layers increase the specific reaction surface area resulting in higher cell power densities. An increase of the anode catalyst loading compared to an equal one of the cathode catalyst loading has greater impact on the cell's power density. Another interesting finding is that increasing the diffusion layers' porosity up to a certain extent, improves the cell power density despite the fact that the parasitic current increases. This is explained by the fact that the reactants' concentrations over the catalysts are increased, leading to lower activation overpotential values, which are the main source of the total cell overpotentials. Moreover, the use of a thicker membrane leads to lower ethanol crossover rate, lower parasitic current and lower mixed potential values in comparison to the use of a thinner one. Finally, according to the model predictions when the cell operates at low current densities the use of a thick membrane is necessary to reduce the negative effect of the ethanol crossover. However, in the case where the cell operates at higher current densities (lower ethanol crossover rates) a thinner membrane reduces the ohmic overpotential leading to higher power density values. (C) 2009 Published by Elsevier B.V

Evaluation of detection criteria for thermal runaway experiments on commercial cells for electric vehicles

With electric vehicles being more and more present on the roads, the possibility of battery fires attracts much attention. Such fires can start as thermal runaway events in a single cell and propagate to neighboring cells.Early detection of thermal runaways is crucial for passenger egress from the vehicle in case of fire. For Regulatory tests, international standards and regulations are available providing criteria based on cell voltage or temperature combined with the temperature rate dT/dt for the detection of thermal runway events. All documents use combinations of several criteria for the identification of thermal runaway events. However, there are differences in the definitions and combinations of these criteria. Based on international guidance documents, we specify thermal runaway detection criteria and apply these to data from thermal runaway tests on commercial single cells for electric vehicles. The runaway events were triggered by nail penetration or by heater on various cell formats.We compare the accuracy of combined criteria and thresholds with regard to their ability for distinguishing between thermal events that led to thermal runaway and those that did not.For our tests, the criteria based on cell temperature and its rate are more reliable than the combination of temperature rate and cell voltage

Sustainability Assessment of Second Life Application of Automotive Batteries

Sustainability Assessment of Second Life Application of Automotive Batteries - presentation of the SASLAB projec

Second life application of automotive Li-ion batteries: Ageing during first and second use and life cycle assessment

The commercialisation of electric vehicles has accelerated in the global market, responding to the need of global CO2 emissions reduction and of energy security. This, in turn, has led to rapidly increasing demand for high-energy density traction Li-ion batteries, and will also translate into an increase of waste xEV batteries after having reached first use End-of-Life in vehicles. Collected batteries are typically recycled. However, their residual capacity could be used in second use applications before recycling."br" The performance of Li-ion cells, namely change of capacity and impedance during calendar and cycle ageing has been analysed beyond the end of first use. Fresh cells, cells aged in the laboratory, and cells aged under real-world driving conditions, have been characterised applying second use stationary grid-scale duty cycles."br" An analysis of the resource efficiency of second-use application of Li-ion batteries from vehicles is presented. This includes an assessment of materials needs and a Material Flow Analysis to estimate the amount of available batteries entering the waste flow after their use in the automotive sector. An adapted life cycle based methodology is presented – taking in consideration experimental performance data – to produce a holistic analysis considering technical, environmental, economical perspective of the foreseen second-life system

Structural, thermomechanical and electrical properties of new (1-x) Ce0.8Nd0.2O2-delta-xBaCe(0.8)Nd(0.2)O(3-delta) composites

In this work composite (1-x)Ce0.8Nd0.2O2-delta-xBaCe(0.8)Nd(0.2)O(3-delta) ceramics were prepared via the one-step citrate-nitrate combustion procedure, and characterised by TG-DSC, XRD analysis, and SEM. Their transport properties were investigated across various temperatures (600-900 degrees C) and oxygen partial pressures (10(-23)-0.21 atm). The XRD data reveals an occurrence of single-phase oxides at x = 0, 1 and two phases with perovskite and fluorite structure at x = 0.25, 0.5, 0.75 in powders calcined at 1100 degrees C. Dense ceramic samples (93-95%) were sintered in air at 1500 degrees C for 3 h. The concentration dependence of the mean grain size is characterized by local minimum at x 0.5, while that of total conductivity exhibited a similar behavior; its minimal value was registered in the sample with the most extended specific grain surface. It was found that the electronic contribution to the total conductivity of the composites is reduced as compared to that of the basic Ce0.8Nd0.2O2-delta and BaCe0.8Nd0.2O3-delta materials. This leads to a better stability in the long-term redox-cycles in comparison with the basic oxides. Additionally, the conductivity in Ce0.8Nd0.2O2-delta decreases by 85%, whereas the conductivity of BaCe0.8Nd0.2O3-delta decreases by 30% after 2 redox-cycles for 200 h at 900 degrees C. The resulting conductivity degradation of the (1-x)Ce0.8Nd0.2O2-delta-xBaCe(0.8)Nd(0.2)O(3-delta) composite is no more than 15%. (C) 2014 Elsevier B.V. All rights reserved