Accession Number : ADA304871

Title :   (23)Na NMR Studies of Na(x)CoO2 Cathode Materials.

Descriptive Note : Interim technical rept.,

Corporate Author : HUNTER COLL NEW YORK DEPT OF PHYSICS AND ASTRONOMY

Personal Author(s) : Stallworth, P. ; Greenbaum, S. ; Ma, Y. ; Ding, L. ; Doeff, M.

PDF Url : ADA304871

Report Date : 26 JAN 1996

Pagination or Media Count : 15

Abstract : Two samples of oxidized sodium cobalt oxide, Na(x)CoO2, where x = 0.3 and 0.7, have been studied by variable-temperature wide-line (23)Na NMR. All spectra exhibit a substantially paramagnetic-shifted response characterized by 2nd-order quadrupole broadening and diamagnetic-shifted weaker response. The paramagnetic shifts are attributed to spins localized on cobalt ions. The 2nd-order quadrupole splitting is resolved for x = 0.7, whereas the lineshapes obtained for x = 0.3 do not show the resolution and indicate a more symmetric sodium environment and/or a greater degree of ion mobility. Lineshapes for the two compositions behave somewhat differently as the temperature is changed, although both samples exhibit gradual line-narrowing over the entire range (-150 to 100 deg C). Spin-lattice relaxation time measurements reflect the presence of inequivalent sodium environments with one distribution of sodium environments characterized by long relaxation times (10 ms - 200 ms) and another set of environments characterized by much shorter times (< 500 micro seconds). jg

Descriptors :   *NUCLEAR MAGNETIC RESONANCE, *SODIUM, *CATHODES, *COBALT OXIDES, IONS, TEMPERATURE, MOBILITY, TRANSITION METALS, ENVIRONMENTS, MATERIALS, QUADRUPOLE MOMENT, SPECTRA, OXIDATION, ELECTRODES, SHIFTING, SYMMETRY, SAMPLING, RELAXATION, LATTICE DYNAMICS, SPIN STATES, ALKALI METALS, ELECTRIC BATTERIES, PARAMAGNETISM.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electrochemical Energy Storage
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE