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 · Sat Jan 01 04:00:00 EST 1983

OSTI ID:5928525

Kaun, T D

Development of molten carbonate fuel cells is concerned with the stability of its NiO (lithiated) cathode. Observations of metallic-nickel deposits within its 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/-K/sub 2/CO/sub 3/. Solubility of NiO as a function of increasing temperature (823 to 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: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5928525
• Report Number(s): CONF-8305100-4; ON: DE83014311
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
300505* -- Fuel Cells-- Electrochemistry
Mass Transfer & Thermodynamics
ALKALI METAL COMPOUNDS
CARBON COMPOUNDS
CARBONATES
CATHODES
CHALCOGENIDES
CHARGED PARTICLES
DEPOSITS
DIRECT ENERGY CONVERTERS
DISPERSIONS
ELECTROCHEMICAL CELLS
ELECTRODES
ELECTROLYTES
FUEL CELLS
HIGH-TEMPERATURE FUEL CELLS
IONS
LITHIUM CARBONATES
LITHIUM COMPOUNDS
MIXTURES
MOLTEN CARBONATE FUEL CELLS
MOLTEN SALTS
NICKEL COMPOUNDS
NICKEL IONS
NICKEL OXIDES
OXIDES
OXYGEN COMPOUNDS
POTASSIUM CARBONATES
POTASSIUM COMPOUNDS
SALTS
SOLUBILITY
STABILITY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
VOLTAMETRY