Relationships among electrochemical, thermodynamic, and oxygen potential quantities in lithium-transition metal-oxygen molten salt cells
The interdependence of thermodynamic parameters, phase equilibria, and electrochemical measurements can be used as a powerful tool in the development of high specific energy cells. These principles were used in the analysis of electrochemical experiments performed on ternary lithium-transition metal-oxide (M = Mn, Fe, and Co) positive electrodes. The free energies of formation of LiMnO/sub 2/, Li/sub 5/FeO/sub 4/, LiFeO/sub 2/, and LiCoO/sub 2/ were found to be -178.21, -399.88, -154.18, and 131.62 kcal/mol at 400/sup 0/C. The electrochemical displacement reactions were found to be reversible in LiCl/KCl molten salt cells over a range of 0.0-3.0 Li equivalents per mol at current densities of 5-15 mA/cm/sup 2/. The equilibrium potential vs. Li was found to be a logarithmic function of the calculated oxygen partial pressure for any tie triangle in which Li/sub 2/O is present, or for any tie triangle containing ternary oxide phases Li /SUB x/ MO /SUB y/ which are only marginally stable with respec to Li/sub 2/O and the relevant binary oxides MO /SUB y/ . Compounds with oxygen partial pressures above 10/sup -25/ atm were found to be unstable in LiCl/KCl electrolyte at 400/sup 0/C.
- Research Organization:
- Department of Materials Science and Engineering, Stanford University, Stanford, California
- OSTI ID:
- 5062327
- Journal Information:
- J. Electrochem. Soc.; (United States), Vol. 131:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
METAL-NONMETAL BATTERIES
ELECTROCHEMISTRY
PHASE STABILITY
THERMODYNAMIC PROPERTIES
CURRENT DENSITY
ELECTRODES
ELECTROLYTES
EQUILIBRIUM
LITHIUM OXIDES
MOLTEN SALTS
NONDESTRUCTIVE TESTING
OXYGEN
PARTIAL PRESSURE
PHASE STUDIES
TRANSITION ELEMENT COMPOUNDS
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CHEMISTRY
ELECTRIC BATTERIES
ELECTROCHEMICAL CELLS
ELEMENTS
LITHIUM COMPOUNDS
MATERIALS TESTING
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SALTS
STABILITY
TESTING
250902* - Energy Storage- Batteries- Performance & Testing