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Electrolytic cell

About: Electrolytic cell is a(n) research topic. Over the lifetime, 9751 publication(s) have been published within this topic receiving 77576 citation(s). more

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Journal ArticleDOI
Kai Zeng1, Dongke Zhang1Institutions (1)
Abstract: Alkaline water electrolysis is one of the easiest methods for hydrogen production, offering the advantage of simplicity. The challenges for widespread use of water electrolysis are to reduce energy consumption, cost and maintenance and to increase reliability, durability and safety. This literature review examines the current state of knowledge and technology of hydrogen production by water electrolysis and identifies areas where R&D effort is needed in order to improve this technology. Following an overview of the fundamentals of alkaline water electrolysis, an electrical circuit analogy of resistances in the electrolysis system is introduced. The resistances are classified into three categories, namely the electrical resistances, the reaction resistances and the transport resistances. This is followed by a thorough analysis of each of the resistances, by means of thermodynamics and kinetics, to provide a scientific guidance to minimising the resistance in order to achieve a greater efficiency of alkaline water electrolysis. The thermodynamic analysis defines various electrolysis efficiencies based on theoretical energy input and cell voltage, respectively. These efficiencies are then employed to compare different electrolysis cell designs and to identify the means to overcome the key resistances for efficiency improvement. The kinetic analysis reveals the dependence of reaction resistances on the alkaline concentration, ion transfer, and reaction sites on the electrode surface, the latter is determined by the electrode materials. A quantitative relationship between the cell voltage components and current density is established, which links all the resistances and manifests the importance of reaction resistances and bubble resistances. The important effect of gas bubbles formed on the electrode surface and the need to minimise the ion transport resistance are highlighted. The historical development and continuous improvement in the alkaline water electrolysis technology are examined and different water electrolysis technologies are systematically compared using a set of the practical parameters derived from the thermodynamic and kinetic analyses. In addition to the efficiency improvements, the needs for reduction in equipment and maintenance costs, and improvement in reliability and durability are also established. The future research needs are also discussed from the aspects of electrode materials, electrolyte additives and bubble management, serving as a comprehensive guide for continuous development of the water electrolysis technology. more

1,933 citations

Journal ArticleDOI
Dawn Bernardi1, Mark W. Verbrugge1Institutions (1)
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. more

1,250 citations

Journal ArticleDOI
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. more

556 citations

Journal ArticleDOI
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 more

551 citations

Journal ArticleDOI
Abstract: Electromotive force measurements on galvanic cells involving solid electrolytes have been made in order to obtain the standard molar free energy of formation of , , , , , , and several phases of the system Ag‐Te at elevated temperatures. more

525 citations

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Topic's top 5 most impactful authors

Yoshinori Nishiki

48 papers, 634 citations

Takayuki Shimamune

35 papers, 349 citations

Shuhei Wakita

19 papers, 176 citations

Masashi Tanaka

16 papers, 160 citations

Yasushi Samejima

15 papers, 49 citations