Electrolytic cell

About: Electrolytic cell is a research topic. Over the lifetime, 9751 publications have been published within this topic receiving 77576 citations.

A Mathematical Model of the Solid‐Polymer‐Electrolyte Fuel Cell

Abstract: This paper presents a mathematical model of the solid-polymer-electrolyte fuel cell and apply it to (i) investigate factors that limit cell performance and (ii) elucidate the mechanism of species transport in the complex network of gas, liquid, and solid phases of the cell. Calculations of cell polarization behavior compare favorably with existing experimental data. For most practical electrode thicknesses, model results indicate that the volume fraction of the cathode available for gas transport must exceed 20% in order to avoid unacceptably low cell-limiting current densities. It is shown that membrane dehydration can also pose limitations on operating current density; circumvention of this problem by appropriate membrane and electrode design and efficient water-management schemes is discussed. The authors' model results indicate that for a broad range of practical current densities there are no external water requirements because the water produced at the cathode is enough to satisfy the water requirement of the membrane.

The intensification technologies to water electrolysis for hydrogen production - A review

Abstract: Water electrolysis derived by renewable energy such as solar energy and wind energy is a sustainable method for hydrogen production due to high purity, simple and green process. One of the challenges is to reduce energy consumption of water electrolysis for large-scale application in future. Cell voltage, an important criterion of energy consumption, consists of theoretical decomposition voltage (U-theta), ohmic voltage drop (i*Sigma R) and reaction overpotential (eta). The kinetic and thermodynamic roots of high cell voltage are analyzed systemically in this review. During water electrolysis, bubble coverage on electrode surface and bubble dispersion in electrolyte, namely bubble effect, result in high ohmic voltage drop and large reaction overpotential. Bubble effect is one of the most key factors for high energy consumption. Based on the theoretical analysis, we summarize and divide recent intensification technologies of water electrolysis into three categories: external field, new electrolyte composition and new thermodynamic reaction system. The fundamentals and development of these intensification technologies are discussed and reviewed. Reaction overpotential and ohmic voltage drop are improved kinetically by external field or new electrolyte composition. The thermodynamic decomposition voltage of water is also reduced by new reaction systems such as solid oxide electrolysis cell (SOEC) and carbon assisted water electrolysis (CAWE). (C) 2013 Elsevier Ltd. All rights reserved.

A Lithium/Dissolved Sulfur Battery with an Organic Electrolyte

Abstract: Prototype cells of the configuration Li/~5M S as , THF, have been characterized with regard to capacity, rate, and rechargeability. Virtually 100% of the theoretical capacity could be realized at 50°C at rates below 1.0 mA/cm2. In high rate cell configurations, 75% cathode utilization is possible at ~4 mA/cm2 (C/3–C/4 rate). The capacities at high rate are enhanced by Lewis acids, although the ultimate cause of rate limitation is passivation of the current collector by discharge products. The self‐discharge rates of Li in contact with 4–5M S (as ) solutions reveal capacity losses of 0.5%/day at 25°C to 4.4%/day at 71°C. Based on the experimental results, a practical energy density of ~300 W‐hr kg−1 is possible using a standard cell design. Results on the battery's rechargeability are briefly reviewed.

Modeling and Experimental Diagnostics in Polymer Electrolyte Fuel Cells

Abstract: This paper presents a fit between model and experiment for well-humidified polymer electrolyte fuel cells operated to maximum current density with a range of cathode gas compositions. The model considers, in detail, losses caused by: (1) interfacial kinetics at the Pt/ionomer interface, (2) gas-transport and ionic-conductivity limitations in the catalyst layer and (3) gas-transport limitations in the cathode backing. The authors` experimental data were collected with cells that utilized thin-film catalyst layers bonded directly to the membrane, and a separate catalyst-free hydrophobic backing layer. This structure allows a clearer resolution of the processes taking place in each of these distinguishable parts of the cathode. In their final comparison of model predictions with the experimental data, they stress the simultaneous fit of a family of complete polarization curves obtained for gas compositions ranging from 5 atm O{sub 2} to a mixture of 5% O{sub 2} in N{sub 2}, employing in each case the same model parameters for interfacial kinetics, catalyst-layer transport, and backing-layer transport. This approach allowed them to evaluate losses in the cathode backing and in the cathode catalyst layer, and thus identify the improvements required to enhance the performance of air cathodes in polymer electrolyte fuel cells. Finally, theymore » show that effects of graded depletion in oxygen along the gas flow channel can be accurately modeled using a uniform effective oxygen concentration in the flow channel, equal to the average of inlet and exit concentrations. This approach has enabled simplified and accurate consideration of oxygen utilization effects.« less