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Title: High performance MCFC using Li/Na electrolyte

The substitution of a lithium/ sodium carbonate (Li/Na) mixture for the lithium/potassium carbonate (Li/K) electrolyte used in MCFCs holds the promise of higher ionic conductivity, higher exchange current density at both electrodes, lower vapor pressure, and lower cathode dissolution rates. However, when the substitution is made in cells optimized for use with the Li/K electrolyte, the promised increase in performance is not realized. As a consequence the literature contains conflicting data with regard to the performance, compositional stability, and chemical reactivity of the Li/Na electrolyte. Experiments conducted at the Institute of Gas Technology (IGT) concluded that the source of the problem is the different wetting characteristics of the two electrolytes. Electrode pore structures optimized for use with Li/K do not work well with Li/Na. Using proprietary methods and materials, IGT was able to optimize a set of electrodes for the Li/Na electrolyte. Experiments conducted in bench-scale cells have confirmed the superior performance of the Li/Na electrolyte compared to the Li/K electrolyte. The Li/Na cells exhibited a 5 to 8 percent improvement in overall performance, a substantial decrease in the rate of cathode dissolution, and a decreased decay rate. The longest running cell has logged over 13,000 hours of operation withmore » a decay rate of less than 2 mV/1000 hours.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
209867
Report Number(s):
DOE/METC--95/1020; CONF-950886--
ON: DE96000554; TRN: 96:001697-0021
Resource Type:
Conference
Resource Relation:
Conference: Fuel cells meeting, Morgantown, WV (United States), 9-10 Aug 1995; Other Information: PBD: Aug 1995; Related Information: Is Part Of Proceedings of the fuel cells `95 review meeting; George, T.J.; PB: 222 p.
Research Org:
USDOE Morgantown Energy Technology Center, WV (United States)
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 36 MATERIALS SCIENCE; LITHIUM CARBONATES; IONIC CONDUCTIVITY; SODIUM CARBONATES; ELECTRODES; DISSOLUTION; DESIGN; MOLTEN CARBONATE FUEL CELLS; STACKS; CURRENT DENSITY