SYNTHESIS AND ELECTROCHEMICAL LITHIUM INSERTION IN POLYANILINE HMWO(6) (M=TA, NB) NANOCOMPOSITES/

The relatively strong Bronsted acidity of the trirutile-like layered o xides HMWO(6) . nH(2)O (M = Ta, Nb) was used to intercalate aniline to form a bilayer of the guest species within the interlayer gap having the formulation [Aniline](0.68)HMWO(6). Thermal treatment in air resul ted in expulsion of half of the aniline, together with polymerization of the remaining aniline within the layers and formation of the novel nanocomposite, PANI(0.34)HMWO(6). FTIR studies showed that the emerald ine salt form of PANI was present. This was consistent with measuremen ts which showed increased conductivity for the nanocomposite (1 x 10(- 6) S/cm), compared to that of the insulator [Aniline](0.68)HMWO(6) (mu ch less than 10(-13) S/cm). The electrochemical properties of these ma terials for lithium insertion reactions were studied using the polymer nanocomposites as cathodes in conventional lithium cells. Electrochem ical insertion of lithium was compared to lithium insertion in the oxi de in the absence of the polymer. In the case of PANI(y)HMWO(6) (M = T a, Nb), the Li diffusion coefficient was measured using the geometrica l surface area, the BET surface area, and the SEM surface area. Irresp ective of the method of surface. area measurement the chemical diffusi on coefficient increases for both Ta and Nb oxides upon insertion of p olyaniline into the host. In the case of HTaWO6 the diffusion coeffici ent increases by more than an order of magnitude (factor of 20). We as cribe this increase in Li ion mobility to a decrease in the Li+ ion in teraction with the host lattice in the polymer nanocomposite.