Improved beta alumina electrolytes for advanced storage batteries

Technical Report · Tue Dec 01 04:00:00 EST 1981

OSTI ID:5557833

De Jonghe, L C

Investigations on the factors determining the mechanisms of electrochemical failure initiation and propagation of polycrystalline sodium beta and beta'' alumina are reported. The investigations have led to the distinction between two modes of failure. Mode I failure involves a cathode plating of sodium into a pre-existing crack. Mode II degradation involves the internal plating of sodium into a pre-existing crack. Mode II degradation involves the internal precipitation of sodium. The Mode I initiation current density thresholds were determined using acoustic emission detection. Experiments below and above the melting point of sodium have been carried out. The results are reported in the form of Weibull failure probability plots. Below the melting point of sodium, the average current density threshold for initiation of Mode I failure depended on temperature, with an activation energy of about 4 kcal/mol. At 350/sup 0/C, it was found that a significant grain size dependence existed, in which large grained material exhibited lower average critical current density thresholds for Mode I initiation than fine grained material. Evidence was also found for internal precipitation of sodium, Mode II degradation. It is indicated that this Mode II degradation probably results from charge trnasfer through a gradient in transport number ratios. These gradients are introduced by the chemical reduction of the beta aluminas when in contact with molten sodium. The chemical reduction has a discoloration associated with it. The nature of this chemical coloration has been examined and is reported. Chemical coloration involves the introduction of oxygen vacancies into the ceramic electrolyte, compensated by electrons. A method is reported that is capable of revealing electrode current density inhomogeneity with the resolution of about 1 micrometer. A method was also developed for revealing the presence of fine, sodium-filled cracks.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5557833
• Report Number(s): EPRI-EM-2160; ON: DE82010989
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
250903* -- Energy Storage-- Batteries-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ACOUSTIC EMISSION TESTING
ACOUSTIC TESTING
ALKALI METALS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CRACKS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
CURRENT DENSITY
ELECTRIC BATTERIES
ELECTRIC CONDUCTIVITY
ELECTRIC-POWERED VEHICLES
ELECTRICAL PROPERTIES
ELECTROCHEMICAL CELLS
ELECTROLYTES
ELECTRON MICROSCOPY
ELEMENTS
ENERGY STORAGE
FAILURES
GRAIN SIZE
HEXAGONAL LATTICES
IONIC CONDUCTIVITY
MATERIALS TESTING
METAL-NONMETAL BATTERIES
METALS
MICROSCOPY
MICROSTRUCTURE
NONDESTRUCTIVE TESTING
OFF-PEAK ENERGY STORAGE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POLYCRYSTALS
SIZE
SODIUM
SODIUM-SULFUR BATTERIES
SOLID ELECTROLYTES
STORAGE
TESTING
VEHICLES