calation of sodium and we present further details of the characterization of the intercalate phases observed.
The misfit layer sulfide of composition (PbS) 1.18 (TiS 2 ) 2 has been studied as a host material for the intercalation of sodium. The discharge curve profile using propylene carbonate (PC) as EXPERIMENTAL the solvent of electrolyte showed that the intercalation process is complex with the appearance of an extended plateau which (PbS) 1.18 (TiS 2 ) 2 was prepared by direct synthesis from suggests the formation of a multiphase region. In fact, an interpowdered elements as described elsewhere (2, 5). Powder mediate phase of sodium content 0.2 mol per formula unit, X-ray diffraction patterns were obtained on a Siemens with basal spacing of 29.9 A Λ, which exceeds by 12.4 A Λthe D500 diffractometer using CuKΝ° radiation and a graphite repeating unit PbS-TiS 2 -TiS 2 , has been observed. This result monochromator. Thermogravimetric analysis (TGA) was is interpreted on the basis of solvent cointercalation. PC molecarried out in a Cahn 2000 electrobalance. cules are located at the interlayer region defined at the interface Chemical sodium intercalation was done by stirring the TiS 2 -TiS 2 . The increase in the sodium content promotes the solid in 0.125 M sodium naftalide solution in tetrahydrofurelease of PC molecules out of the layers. The interlayer expanran (THF) in a dry box (M. Braun) under an Ar atmosion of the new phase formed is similar to that observed upon sphere. Electrochemical measurements were performed in intercalation with sodium naftalide and is consistent with the Na/NaClO 4 -PC/sulfide cells assembled and discharged location of sodium ions in the interstitial sites defined by two consecutive sulfur slabs. Under room conditions this phase under argon atmosphere. Intermediate products were preabsorbs water. The final expansion of ca. 6 A Λis consistent with pared to observe structural changes due to sodium insera bilayer hydration process.