Degradation of sodium beta''-alumina electrolyte in contact with sulfur/sodium polysulfide melts

Technical Report · Thu May 01 00:00:00 EDT 1986

OSTI ID:5419851

Liu, M

Immersion of sodium ..beta..'' alumina electrolyte in sodium polysulfide and pure sulfur melts, at Na/S battery operation temperatures, showed that the electrolyte was chemically attacked by the melts. The corrosion reactions mostly initiated and concentrated on defect areas, and were catalyzed by the presence of impurities such as water, moist air, oxygen, etc. The corrosion power of sodium polysulfide melts increased going from Na/sub 2/S/sub 2/ to Na/sub 2/S/sub 5/. The reaction products at the interface were believed to be Na/sub 2/SO/sub 4/, NaAl(SO/sub 4/)/sub 2/, Al/sub 2/(SO/sub 4/)/sub 3/, NaHSO/sub 4/, Na/sub 2/CO/sub 3/, NaOH, etc. Recrystallization of the sulfates occurred on preferred areas after saturation. Corrosion products of transition metals also deposited on the electrolyte surface. Degraded sodium ..beta..''-alumina electrolytes, removed from four commercial cells, were characterized. Observations indicated that during cell operation a protective layer formed on the electrolyte surface. This layer, similar to that found in the static tests, spalled off when inhomogeneous ionic currents cause the nonuniform formation of compounds underneath it during cell operation, leading to continued electrochemical degradation. The intergranular regions were corroded preferentially due to local current concentration. The influence of the microstructure of the electrolyte, impurity contamination, cell construction, and cycling conditions on electrolyte degradation are discussed.

• Research Organization: Lawrence Berkeley Lab., CA (USA). Materials and Molecular Research Div.
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5419851
• Report Number(s): LBL-21563; ON: DE86015132
• Resource Relation: Other Information: Thesis. Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
SODIUM-SULFUR BATTERIES
SOLID ELECTROLYTES
CORROSION
BETA-W LATTICES
CHEMICAL REACTIONS
INTERFACES
SODIUM SULFIDES
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRIC BATTERIES
ELECTROCHEMICAL CELLS
ELECTROLYTES
METAL-NONMETAL BATTERIES
SODIUM COMPOUNDS
SULFIDES
SULFUR COMPOUNDS
250903* - Energy Storage- Batteries- Materials
Components
& Auxiliaries