Synthesis and properties of poorly crystalline molybdenum sulfide thin films as cathode materials

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6123310

Shin, H K

This study concerned the development of a cathode material for the secondary lithium battery which requires high intercalation ratio of lithium atoms for high energy density and high electrical conductivity for high current density of the cell. Non-crystalline molybdenum sulfides are promising candidates as cathode materials due to high intercalation ratio of lithium atoms per molybdenum atom. Poorly-crystalline (pc-) molybdenum sulfide thin films were synthesized by the Activated Reactive Evaporation (ARE) technique evaporating pure molybdenum rod in an H{sub 2}S plasma. And niobium, acting as an acceptor, was doped to molybdenum sulfide films in order to increase the conductivity. Sulfur content of the films varied in a wide range from 61 at.% to 75 at.% by changing the deposition variables, with corresponding stoichiometry of MoS{sub X} (1.6 {le} X {le} 3.0) as a sulfur deficient film or Mo{sub y}S{sub 2} (0.67 {le} y 1.25) as a metal deficient film. Resistivity was sensitive to sulfur content and increased monotonically as the sulfur content increased. Among the deposition variables, deposition rate was most dominant: resistivity increased initially and then decreased after reaching a peak with increasing deposition rate. As anode current, the second dominant variable, increased, resistivity decreased disagreeing with conventional gas dissociation theory. X-ray diffraction pattern showed that films are poorly-crystalline and Raman spectra showed that films are mixtures of hexagonal MoS{sub 2} and amorphous MoS{sub 3}. Conduction mechanisms determined from the behavior of conductivity against temperature also showed dual characteristics of both structures within experimental errors.

• Research Organization: California Univ., Los Angeles, CA (USA)
• OSTI ID: 6123310
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
250903* -- Energy Storage-- Batteries-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360603 -- Materials-- Properties
CATHODES
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
CURRENT DENSITY
DIFFRACTION
DOPED MATERIALS
ELECTRIC BATTERIES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTROCHEMICAL CELLS
ELECTRODES
FILMS
LITHIUM-SULFUR BATTERIES
MATERIALS
METAL-NONMETAL BATTERIES
MOLYBDENUM COMPOUNDS
MOLYBDENUM SULFIDES
PERFORMANCE
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
SCATTERING
SULFIDES
SULFUR COMPOUNDS
SYNTHESIS
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION