Electrochemical Properties of Nanostructured Amorphous, Sol-gel-Synthesized TiO₂/Acetylene Black Composite Electrodes

Amorphous titanium oxide was prepared by a sol-gel route employing Ti(IV) alkoxide as a starting agent. The average size of the primary particles was about 4 nm, and the Brunauer-Emmett-Teller specific surface area was 390 m ² g^-1. Addition of acetylene black in synthesis allowed us to obtain the composite of titania and carbon materials. The composite materials could be galvano-staticly discharged and charged around 2 V vs. Li/Li⁺. After thermal treatment at 330°C the composite showed specific capacity above 125 mA h g^-1, even under large discharge current of 10 A g^-1. Based on the relationship between specific capacity and current density, the chemical diffusion coefficient of lithium was estimated to be 6 × 10^-12 cm² s^-1.