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[en] The deactivation behaviour of Ni/PTFE electrodes operating with hydrogen gas containing CO impurity was studied in half cell experiments under potentiostatic conditions. The decay of electrode current densities with respect to time is measured. It is observed that the electrode is deactivated and the electrode current densities reached lower steady state values when subjected to CO impurities in the hydrogen stream. The recovery, which is only partial under all conditions except at 72 deg C, after removal of the contaminant CO impurities, is also recorded. A total of 12 runs were carried out at 3 different temperatures. The effect of the CO impurity concentration is investigated at each temperature. The effects of electrode overpotential and electrolyte concentration are also studied. 9 figs., 1 tab., 14 refs

[en] Alkaline low temperature fuel cells are prepared and investigated; PTFE bonded gas diffusion electrodes for high current densities (about 400 mA/cm²) are prepared using a rolling technique. These electrodes are characterized by electrochemical and physical methods, focusing on preparation, reactivation process and degradation effects. After reactive mixing and rolling of PTFE (5-10 wt pc) with pre-activated and stabilized Raney nickel catalyst, the specific surface of the electrode is very small. The typical micropore systems (1.5-2.5 nm) of Raney nickel are not observed by BET-techniques. However, after electrochemical reactivation of the electrode, the active micropore system reappears depending on current density and activation time. The chemical surface composition of gas diffusion electrodes has been investigated by XPS techniques and electrochemical measurements depending on time of operation to get basic data for long term operation effects and degradation steps. From these experimental results, model considerations are discussed. 8 figs., 10 refs

[en] The future of transportation is rapidly being defined by the environmental concerns emanating from the current excessive usage of highly polluting and rapidly depleting fuels. Thus, there is a significant drive towards the development of highly energy and power efficient vehicles and transport systems which could primarily use energy derived from clean, green and renewable resources. These include solar energy, wind energy, tidal energy etc. Since these sources are not constantly available and are quite temperamental in time domain, the corresponding harnessed energy must necessarily be stored in robust and safe manner for subsequent use. In the case of transportation, the storage has to be of dual type; large scale local storage station for charging vehicle systems and mobile/portable storage systems to be boarded on vehicles. Battery systems provide attractive options for both. These objectives, but there area number of critical issues that need to be resolved before the large scale implementation of the dream transportation scenario can be realized. The research in this domain is primarily focusing on materials and system architecture related challenges which also include concerns pertaining to safety and economic viability. There are certain country specific challenges as well which relate to the materials availability and dependence on other countries for battery materials. After briefly outlining the scenario, presented here are some examples of the research in developing new anode and cathode materials for alkali ion (Li/Na) batteries. This will include different carbon based materials as well as carbon based composites, Si/Sn nanostructures, oxides, sulfides and phosphides, as well as some cases of 2D materials. (author)

[en] Based on the VARTA fuel cell technology of the late 60's and the new and inexpensive gas diffusion electrodes with their simple manufacturing process, a new kind of advanced alkaline Eloflux fuel cells and electrolysis cells have been developed. In an Eloflux fuel cell, the electrodes are very close together, only separated by a very thin porous separator. The electrolyte flow, carrying off heat and water, passes now at the outside of the electrode pair; the reaction water leaves the electrode at the back side. Cell blocks and the regeneration of the electrolyte in the fuel cells are discussed. Performance characteristics are given. 11 figs., 9 refs

[en] The development of metal-free carbon-based catalysts for alkaline fuel cells has been the subject of current interest, because of the low cost and improving fuel cell efficiency. Particularly, nitrogen-doped carbon shows prominent results. Here, we show an oxygen reduction reaction (ORR) activity of nitrogen-doped graphene-like carbon materials (N-GLC) prepared by heating bagasse-derived carbon and melamine in a 1:15 ratio. The N-GLC catalyst displays excellent electro-catalytic activity towards the ORR with an onset potential of 0.92 V vs. reversible hydrogen electrode (RHE) in alkaline media (0.1 M KOH). Moreover, the half-wave (E_1/2) potential 0.83 V is almost the same compared to Pt-C (40 wt%) catalyst and the diffusion limiting current of 4 mA cm^-2. The rotating ring disc experiment showed a four-electron pathway (n = 3.65) with the moderate peroxide (HO^-2) yield. Due to its promising ORR activity and long-term electrochemical stability, N-GLC catalyst is used in alkaline anion exchange membrane fuel cell (AEMFC) as a single cell, about 6 mW cm^- peak power density was achieved at the load current density of ~20 mA cm^-. So the N-GLC can be a cheap alternative ORR catalyst for AEMFC applications. (author)

[en] The first phase of HYSOLAR, which ended in 1991, was focusing mainly on investigation, test and improvement of hydrogen production technologies. This paper shortly reviews the most important results: a 2 kW test and research facility in Jeddah; fundamental research in the fields of photo-electrochemistry, advanced alkaline electrolysis and alkaline fuel cells; system studies and decentralized hydrogen utilization; program for education. An outlook into the second phase program, where more emphasis is laid on hydrogen utilization technologies, is also included. 1 tab., 93 refs

[en] Full Text:Saccharides, like glucose, fructose and lactose, are ideal renewable fuels. They have high energy content, are safe, transportable, easy to store, non-flammable, non poisonous, non-volatile, odorless, easy to produce anywhere and abundant. Fuel Cells are electro-chemical devices capable to convert chemical energy into electrical energy from fuels, with theoretical efficiencies higher than 0.8 at room temperatures and with low pollutant emissions. Fuel Cells that can produce electricity form saccharides will be able to replace batteries, power electrical plants from biomass wastes, and serve as engines for transportation. In spite of these advantages, saccharide fuelled fuel cells are no available yet. Two obstacles hinder the feasibility of this potentially revolutionary device. The first is the high stability of the saccharides, which requires a good catalyst to extract the electrons from the saccharide fuel. The second is related to the nature of the Fuel Cells: the physical process takes place at the interface surface between the fuel and the electrode. In order to obtain high densities, materials with high surface to volume ratio are needed. Efforts to overcome these obstacles will be described. The use of saccharides as a fuel was treated from the thermodynamic point of view and compared with other common fuels currently used in fuel cells. We summarize measurements performed in a membrane less Alkaline Fuel Cell, using glucose as a fuel and KOH as electrolyte. The anode has incorporated platinum particles and operated at room temperature. Measurements were done, at different concentrations of glucose, of the Open Circuit Voltage, Polarization Curves and Power Density as function of the Current Density. The maximum Power Density reached was 0.61 mW/cm² when the Current density was 2.13 mA/cm² and the measured Open Circuit Voltage was 0.771 V

[en] Direct conversion of chemical energy into electricity (without intermediate heat generation) is a long-established method to improve the efficiency of power generation, as well as to reduce polluting emissions from thermal plants. The origins of fuel cells, as well as their operating principles, are dealt with. Then, various types of cells are taken into consideration, on the basis of both their characteristics and the operating principles of electrolytes. Finally, structure and operation of Polymer Electrolyte Membrane Fuel Cells (PEMFC), Alkaline Fuel Cells (AFC) and Phosphoric Acid Fuel Cells (PAFC) are described

[en] The Alkaline Fuel Cell (AFC) was the first fuel cell successfully put into practice, a century after William Grove patented his 'hydrogen battery' in 1839. The space program provided the necessary momentum, and alkaline fuel cells became the power source for both the U.S. and Russian manned space flight. Astris Energi's mission has been to bring this technology down to earth as inexpensive, rugged fuel cells for everyday applications. The early cells, LABCELL 50 and LABCELL 200 were aimed at deployment in research labs, colleges and universities. They served well in technology demonstration projects such as the 1998 Mini Jeep, 2001 Golf Car and a series of portable and stationary fuel cell generators. The present third generation POWERSTACK MC250 poised for commercialization is being offered to AFC system integrators as a building block of fuel cell systems in numerous portable, stationary and transportation applications. It is also used in Astris' own E7 and E8 alkaline fuel cell generators. Astris alkaline technology leads the way toward economical, plentiful fuel cells. The paper highlights the progress achieved at Astris, improvements of performance, durability and simplicity of use, as well as the current and future thrust in technology development and commercialization. (author)