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Title: Carbon Ionic Conductors for use in Novel Carbon-Ion Fuel Cells

Abstract

Carbon-consuming fuel cells have many potential advantages, including increased efficiency and reduced pollution in power generation from coal. A large amount of work has already been done on coal fuel cells that utilize yttria-stabilized zirconium carbide as an oxygen-ion superionic membrane material. But high-temperature fuel cells utilizing yttria-stabilized zirconium require partial combustion of coal to carbon monoxide before final oxidation to carbon dioxide occurs via utilization of the oxygen- ion zirconia membrane. A carbon-ion superionic membrane material would enable an entirely new class of carbon fuel cell to be developed, one that would use coal directly as the fuel source, without any intervening combustion process. However, a superionic membrane material for carbon ions has not yet been found. Because no partial combustion of coal would be required, a carbon-ion superionic conductor would allow the direct conversion of coal to electricity and pure CO{sub 2} without the formation of gaseous pollutants. The objective of this research was to investigate ionic lanthanide carbides, which have an unusually high carbon-bond ionicity as potential superionic carbide-ion conductors. A first step in this process is the stabilization of these carbides in the cubic structure, and this stabilization has been achieved via the preparation of pseudobinarymore » lanthanide carbides. The diffusion rates of carbon have been measured in these carbides as stabilized to preserve the high temperature cubic structure down to room temperature. To prepare these new compounds and measure these diffusion rates, a novel, oxide-based preparation method and a new C{sup 13}/C{sup 12} diffusion technique have been developed. The carbon diffusion rates in La{sup 0.5}Er{sup 0.5}C{sub 2}, Ce{sup 0.5}Er{sup 0.5}C{sub 2}, and La{sup 0.5}Y{sup 0.5}C{sub 2}, and Ce{sup 0.5}Tm0.5C{sub 2} modified by the addition of 5 wt %Be{sub 2}C, have been determined at temperatures from 850 C to 1150 C. The resulting diffusion constants as measured were all less than 10{sup -11} cm{sup 2}/sec, and therefore these compounds are not superionic. However, there remain a large number of potentially superionic pseudobinary lanthanide compounds and a number of alternate ionic carbides which might act as dopants to produce vacancies on the carbon-ion sublattice and thereby increase carbon-ion diffusion rates. The discovery of a superionic carbon conductor would usher in a truly revolutionary new coal technology, and could dramatically improve the way in which we generate electricity from coal. The work completed to date is a promising first step towards this end.« less

Authors:
; ;
Publication Date:
Research Org.:
Duke Univ., Durham, NC (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
875826
DOE Contract Number:  
FG26-03NT41804
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 01 COAL, LIGNITE, AND PEAT; CARBIDES; CARBON; CARBON DIOXIDE; CARBON IONS; CARBON MONOXIDE; COAL FUEL CELLS; COMBUSTION; DIFFUSION; FUEL CELLS; HIGH-TEMPERATURE FUEL CELLS; OXIDATION; POWER GENERATION; RARE EARTHS; STABILIZATION; ZIRCONIUM CARBIDES

Citation Formats

Cocks, Franklin H, Simmons, W Neal, and Klenk, Paul A. Carbon Ionic Conductors for use in Novel Carbon-Ion Fuel Cells. United States: N. p., 2005. Web. doi:10.2172/875826.
Cocks, Franklin H, Simmons, W Neal, & Klenk, Paul A. Carbon Ionic Conductors for use in Novel Carbon-Ion Fuel Cells. United States. https://doi.org/10.2172/875826
Cocks, Franklin H, Simmons, W Neal, and Klenk, Paul A. 2005. "Carbon Ionic Conductors for use in Novel Carbon-Ion Fuel Cells". United States. https://doi.org/10.2172/875826. https://www.osti.gov/servlets/purl/875826.
@article{osti_875826,
title = {Carbon Ionic Conductors for use in Novel Carbon-Ion Fuel Cells},
author = {Cocks, Franklin H and Simmons, W Neal and Klenk, Paul A},
abstractNote = {Carbon-consuming fuel cells have many potential advantages, including increased efficiency and reduced pollution in power generation from coal. A large amount of work has already been done on coal fuel cells that utilize yttria-stabilized zirconium carbide as an oxygen-ion superionic membrane material. But high-temperature fuel cells utilizing yttria-stabilized zirconium require partial combustion of coal to carbon monoxide before final oxidation to carbon dioxide occurs via utilization of the oxygen- ion zirconia membrane. A carbon-ion superionic membrane material would enable an entirely new class of carbon fuel cell to be developed, one that would use coal directly as the fuel source, without any intervening combustion process. However, a superionic membrane material for carbon ions has not yet been found. Because no partial combustion of coal would be required, a carbon-ion superionic conductor would allow the direct conversion of coal to electricity and pure CO{sub 2} without the formation of gaseous pollutants. The objective of this research was to investigate ionic lanthanide carbides, which have an unusually high carbon-bond ionicity as potential superionic carbide-ion conductors. A first step in this process is the stabilization of these carbides in the cubic structure, and this stabilization has been achieved via the preparation of pseudobinary lanthanide carbides. The diffusion rates of carbon have been measured in these carbides as stabilized to preserve the high temperature cubic structure down to room temperature. To prepare these new compounds and measure these diffusion rates, a novel, oxide-based preparation method and a new C{sup 13}/C{sup 12} diffusion technique have been developed. The carbon diffusion rates in La{sup 0.5}Er{sup 0.5}C{sub 2}, Ce{sup 0.5}Er{sup 0.5}C{sub 2}, and La{sup 0.5}Y{sup 0.5}C{sub 2}, and Ce{sup 0.5}Tm0.5C{sub 2} modified by the addition of 5 wt %Be{sub 2}C, have been determined at temperatures from 850 C to 1150 C. The resulting diffusion constants as measured were all less than 10{sup -11} cm{sup 2}/sec, and therefore these compounds are not superionic. However, there remain a large number of potentially superionic pseudobinary lanthanide compounds and a number of alternate ionic carbides which might act as dopants to produce vacancies on the carbon-ion sublattice and thereby increase carbon-ion diffusion rates. The discovery of a superionic carbon conductor would usher in a truly revolutionary new coal technology, and could dramatically improve the way in which we generate electricity from coal. The work completed to date is a promising first step towards this end.},
doi = {10.2172/875826},
url = {https://www.osti.gov/biblio/875826}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}