Molten silver as a direct carbon fuel cell anode

Javadekar, Ashay; Jayakumar, Abhimanyu; Pujara, Rohan; Vohs, John M.; Gorte, Raymond J.

doi:10.1016/j.jpowsour.2012.04.096

Cited by 30 publications

(16 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this regard, this process resembles chemical looping combustion, but unlike CLC, the metal oxide is formed electrochemically while generating power, and not chemically. Many molten metal anodes are considered for this purpose, including Sn , Bi , In , Pb , Sb , Fe , and Ag . In the case of molten Sn, the corresponding reactions in the anode chamber can be written as,

S n_{(l)} + 2 {O^{2 -}}_{(italicelectrolyte)} = S n O_{2 ((), s)} + 4 {e^{prefix-}}_{(italicelectrode)}

C_{(s)} + S n O_{2 ((), s)} = C O_{2 ((), g)} + S n_{(l)}

…”

Section: Types Of Carbon Fuel Cellsmentioning

confidence: 99%

Progress in carbon fuel cells for clean coal technology pipeline

Gür

2015

Int. J. Energy Res.

View full text Add to dashboard Cite

Summary As coal use for electricity production is expected to increase substantially in the next several decades, our carbon‐constraint world demands sustainability, which requires urgent advances in coal power generation to achieve significantly reduced footprints on the environment, water resources, and climate change. Carbon fuel cells (CFC) that can electrochemically convert solid fuels directly into electricity hold the potential to leap‐frog the technological evolution process towards achieving clean coal power generation by offering dramatically higher conversion efficiencies and proportionately lower carbon intensity, emissions, and water demand, while producing a highly concentrated CO2 flue stream that is nearly capture‐ready. This article provides the prospects and overview of CFCs in the context of other advanced coal power generation technologies, and discusses both the status of research progress in this exciting and emerging technology, and also some of the challenges yet to overcome. Research up to date has demonstrated remarkable power densities up to nearly 900 mW/cm2 for pyrolyzed carbon and 450 mW/cm2 for untreated coal char. Also, conversion efficiencies around 50% were experimentally demonstrated for coal in a solid oxide‐based CFC system, while calculations estimated an efficiency of 80% for converting pyrolytic carbon fuel in a molten carbonate‐based CFC system. With such practically significant performance, figures coupled with potentially high conversion efficiencies and an impressive list of environmental merits, CFCs gain a rightful place in the clean coal power technology pipeline. Copyright © 2015 John Wiley & Sons, Ltd.

show abstract

S n_{(l)} + 2 {O^{2 -}}_{(italicelectrolyte)} = S n O_{2 ((), s)} + 4 {e^{prefix-}}_{(italicelectrode)}

C_{(s)} + S n O_{2 ((), s)} = C O_{2 ((), g)} + S n_{(l)}

…”

Section: Types Of Carbon Fuel Cellsmentioning

confidence: 99%

Progress in carbon fuel cells for clean coal technology pipeline

Gür

2015

Int. J. Energy Res.

View full text Add to dashboard Cite

show abstract

“…If oxygen were merely soluble in the molten metal, the OCV would vary with the amount of oxygen. A variable OCV is observed in cells operating on molten Pb 14 and molten Ag 13 but not with molten Sb. 10,19 Second, the large difference in densities between Sb (6.7 g/cm 3 ) and Sb 2 O 3 (5.2 g/cm 3 ) implies that natural convection will be important in this system.…”

Section: Resultsmentioning

confidence: 96%

Zirconia-Based Electrolyte Stability in Direct-Carbon Fuel Cells with Molten Sb Anodes

Zhou

Vohs

et al. 2015

J. Electrochem. Soc.

View full text Add to dashboard Cite

Direct carbon fuel cells (DCFC) that use zirconia-based electrolytes and molten Sb anodes have much promise for the efficient conversion of carbonaceous solid fuels into electricity. However, etching of the electrolyte, and ultimately cell failure, has been observed during operation. In this study, we have investigated this etching phenomenon as a function of the electrolyte composition and cell operating conditions and demonstrated that it is not electrochemical in nature, but rather results from reaction between the electrolyte and Sb 2 O 3 that is produced during cell operation. Etching was also observed when a yttria-stabilized zirconia ( Electrical power generation in a solid oxide fuel cell (SOFC) directly utilizing solid, carbonaceous fuels (e.g. coal and biomass) would provide significant benefits including high energy conversion efficiency. CO 2 sequestration, if needed, is easy since the exhaust gas from the anode is highly concentrated.1 Direct utilization of solid carbonaceous fuels would eliminate the need for gasification and steam reforming steps leading to great simplification of the overall system. The transfer of oxide ions from the electrolyte to the solid fuel is often found to be the limiting step for SOFCs operating on solid fuels.3 Among various approaches to facilitate this transfer, 4-7 one of the most promising routes is to use of molten-metal electrodes. [8][9][10] In this scheme, the anode reaction occurs in two steps:The first step (Equation 1) is the electrochemical oxidation of some portion of the metal in the anode at the electrolyte-anode interface. The oxidized metal is then transported (via diffusion, natural convection or mechanical mixing) to access solid fuel where the carbon is oxidized while reducing metal oxide back to metal (Equation 2). Sn previously attracted much attention as the molten metal phase for this process. 8,9Unfortunately, there is evidence that a solid SnO 2 layer forms at the electrolyte-anode interface during fuel cell operation, inhibiting further facile transfer of the oxygen from the electrolyte, resulting in high electrode losses. 11,12 While this can be avoided by using a molten metal with high oxygen solubility that does not form a stable bulk oxide phase at SOFC operating temperatures (such as Ag), electrode impedances can still be high due to slow diffusion of oxide ions within the molten metal. 13In our opinion, the metal that has provided the most intriguing results as an anode for this type of direct carbon fuel cell (DCFC) is Sb.14-16 Both Sb (melting point 903 K) and Sb 2 O 3 (melting point 929 K) become liquid at SOFC operation temperature ranging from 973 to 1073 K. This precludes the formation of a solid metal-oxide film at the electrolyte-anode interface as in the case of Sn. Furthermore, reduction of Sb 2 O 3 by carbon is facile and has been practiced industrially for more than 100 years.17 Although the Open-Circuit Voltage (OCV) for Sb oxidation is only 0.75 V at 973 K, the energy losses associated with this low potential are largely c...

show abstract

“…The other major areas requiring effort to improve the DCFC performance and take the technology to commercialization stage are: development of anode materials that can extend TPBs to increase solid fuel reactive sites for example the use of mixed ion conductors or partly utilize gaseous by-products of solid carbon fuel [51]; investigations on carbon fuel characteristics and required level of fuel processing that maximizes its reactivity at the fuel/electrode or electrode/electrolyte interface and reduce anode degradation and prolong fuel cell life [52]; development of electrode supported cell designs preferably cathode supported to minimize the electrolyte and anode thickness to reduce resistive losses across electrolyte and enhance fuel transport/diffusion through anode [53]; and development of cell materials for low temperature operation to minimize materials degradation issues [54]. General programs looking generically at 'performance' or 'degradation' across the whole field, rather than focusing on one or two specific system concepts, are unlikely to result in the driving of this technology towards a commercial product.…”

Section: R E T R a C T E D R E T R A C T E D R E T R A C T E D R E T mentioning

confidence: 99%

Progress and Challenges in the Direct Carbon Fuel Cell Technology

Chen

Gao

Long

et al. 2015

ILCPA

View full text Add to dashboard Cite

Fuel cells are under development for a range of applications for transport, stationary and portable power appliances. Fuel cell technology has advanced to the stage where commercial field trials for both transport and stationary applications are in progress. Direct Carbon Fuel Cells (DCFC) utilize solid carbon as the fuel and have historically attracted less investment than other types of gas or liquid fed fuel cells. However, volatility in gas and oil commodity prices and the increasing concern about the environmental impact of burning heavy fossil fuels for power generation has led to DCFCs gaining more attention within the global study community. A DCFC converts the chemical energy in solid carbon directly into electricity through its direct electrochemical oxidation. The fuel utilization can be almost 100% as the fuel feed and product gases are distinct phases and thus can be easily separated. This is not the case with other fuel cell types for which the fuel utilization within the cell is typically limited to below 85%. The theoretical efficiency is also high, around 100%. The combination of these two factors, lead to the projected electric efficiency of DCFC approaching 80% -approximately twice the efficiency of current generation coal fired power plants, thus leading to a 50% reduction in greenhouse gas emissions. The amount of CO 2 for storage/sequestration is also halved. Moreover, the exit gas is an almost pure CO 2 stream, requiring little or no gas separation before compression for sequestration. Therefore, the energy and cost penalties to capture the CO 2 will also be significantly less than for other technologies. Furthermore, a variety of abundant fuels such as coal, coke, tar, biomass and organic waste can be used. Despite these advantages, the technology is at an early stage of development requiring solutions to many complex challenges related to materials degradation, fuel delivery, reaction kinetics, stack fabrication and system design, before it can be considered for commercialization. This paper, following a brief introduction to other fuel cells, reviews in detail the current status of the direct carbon fuel cell technology, recent progress, technical challenges and discusses the future of the technology.

show abstract

Molten silver as a direct carbon fuel cell anode

Cited by 30 publications

References 29 publications

Progress in carbon fuel cells for clean coal technology pipeline

Progress in carbon fuel cells for clean coal technology pipeline

Zirconia-Based Electrolyte Stability in Direct-Carbon Fuel Cells with Molten Sb Anodes

Progress and Challenges in the Direct Carbon Fuel Cell Technology

Contact Info

Product

Resources

About