Solubility of the NiO fuel cell cathode in Li/sub 2/CO/sub 3/-K/sub 2/CO/sub 3/ melts as determined by cyclic voltammetry

Conference · Sun May 01 04:00:00 EDT 1983 · Proc. - Electrochem. Soc.; (United States)

OSTI ID:6145262

Kaun, T D

Development of molten carbonate fuel cells is concerned with the stability of the NiO (lithiated) cathode. Observations of metallic nickel deposits within the electrolyte matrix have prompted investigation into modes of operation to enhance NiO stability as well as a search for alternative cathode materials. In this paper, cyclic voltammetry has been applied to examine Ni/sup 2 +/ concentration in Li/sub 2/CO/sub 3/-K/sub 2/CO/sub 3/ melts with NiO present. A test cell with three gold electrodes, one being the reference with 1/3 O/sub 2/ - 2/3 CO/sub 2/ gas purge, employed voltage limits +0.2 to -1.0 V. Data and physical samples were collected at temperatures between 823 and 1023 K. The Li/sub 2/CO/sub 3/-K/sub 2/CO/sub 3/ melt compositions ranged from 65 to 38 mol % Li/sub 2/CO/sub 3/. Solubility of NiO as a function of increasing temperature (823-1023 K) differed for the respective dry carbonate melt compositions, increasing in a range from 5 to 45 wt ppm Ni for 62 mol % Li/sub 2/CO/sub 3/, while decreasing in a range from 15 to 5 wt ppm Ni for 38 mol % Li/sub 2/CO/sub 3/. In 50 mol % Li/sub 2/CO/sub 3/, NiO solubility increased from 10 wt ppm Ni at 823 K to 30 wt ppm Ni at 1023 K. Humidified cathode gas significantly increased NiO solubility (up to 10 X). The increase was partially reversed by dry gas purge with a 2 to 4 fold increase of Ni concentration remaining even after days of dry gas purge. Humidified gas did not affect the coefficients of the respective NiO solubility functions with temperature.

• Research Organization: Chemical Technology Division, Argonne National Laboratory, Argonne, Illinois
• OSTI ID: 6145262
• Report Number(s): CONF-8305100-
• Conference Information: Journal Name: Proc. - Electrochem. Soc.; (United States) Journal Volume: 84-2
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
300503* -- Fuel Cells-- Materials
Components
& Auxiliaries
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400 -- Electrochemistry
ALKALI METAL COMPOUNDS
CARBON COMPOUNDS
CARBONATES
CATHODES
CHALCOGENIDES
DIRECT ENERGY CONVERTERS
ELECTROCHEMICAL CELLS
ELECTRODES
ELECTROLYTES
FUEL CELLS
HIGH-TEMPERATURE FUEL CELLS
LITHIUM CARBONATES
LITHIUM COMPOUNDS
MOLTEN CARBONATE FUEL CELLS
NICKEL COMPOUNDS
NICKEL OXIDES
OXIDES
OXYGEN COMPOUNDS
POTASSIUM CARBONATES
POTASSIUM COMPOUNDS
SOLUBILITY
SOLVENT PROPERTIES
STABILITY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE
VOLTAMETRY