Evaluation of titanium dioxide (anatase) from oxalato-polytitanate as an active material for rechargeable lithium batteries

A kind of polytitanic acid incorporated with oxalate ligands was synthesized by a reaction of titanium carbide with hydrogen peroxide. On thermal decomposition at relatively low temperature (330 degrees C), it yielded powder of titanium dioxide (anatase), containing carbon to some extent (C/Ti = O.06). Carbon was amorphous according to the Raman spectroscopy, and probably dispersed over the surface of anatase particles with a relatively high BET area (Brunauer-Emmett-Teller measurement method) (-70 m(2)/g), although this was not directly observed with scanning electron microscopy. We found that incorporation of carbon enhanced performance of anatase as an active material for nonaqueous lithium batteries. The specific capacity associated with reversible insertion of lithium was increased to 167 MAh/g, as compared to 30 for carbon-free anatase synthesized from a similar precursor. Moreover, a decline in capacity with repeated charge-discharge cycles was very much suppressed by incorporation of carbon. Impedance measurements showed that carbon played a role in increasing the effective area of the interface involved in electrochemical insertion.