Degradation phenomena in solid electrolytes

Technical Report · Thu Nov 01 04:00:00 EST 1984

OSTI ID:6117908

Hitchcock, D C

The critical current density above which degradation occurs in beta-alumina has been determined by means of acoustic emissions tests on sodium/sulfur cells. Cells were tested by passing a current which increased linearly with time, as the stress or strain is increased in mechanical testing. The critical current density was found to depend on the rate of increase of the current density, indicating that some type of time dependent degradation is occurring. Microstructural investigation of used electrolytes showed some dissolution of electrolyte from inside cracks, and some used electrolytes had a degraded layer on the sodium exit surface, again indicating some type of time dependent attack. The degradation is attributed to mechanical cracking due to Poiseuille pressure as sodium flows out of surface flaws during charging at high current density. At low current density, long time chemical attack due to changes in the composition of the sodium electrode becomes important. Crack velocity as a function of crack length and current density is estimated for this stress corrosion.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6117908
• Report Number(s): LBL-18710; ON: DE85007066
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
250903* -- Energy Storage-- Batteries-- Materials
Components
& Auxiliaries
ACOUSTIC EMISSION TESTING
ACOUSTIC TESTING
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CRACK PROPAGATION
CRYSTAL STRUCTURE
CURRENT DENSITY
DECOMPOSITION
ELECTRIC BATTERIES
ELECTROCHEMICAL CELLS
ELECTROLYTES
MATERIALS TESTING
METAL-NONMETAL BATTERIES
MICROSTRUCTURE
NONDESTRUCTIVE TESTING
OXIDES
OXYGEN COMPOUNDS
SODIUM-SULFUR BATTERIES
SOLID ELECTROLYTES
TESTING