Influence of mesoporosity and carbon electronic wiring on electrochemical performance of anatase titania

Abstract

The combined benefits of mesoporosity and in situ grown conductive amorphous carbon on lithium storage capacity of anatase TiO₂ are discussed here. Micron-sized anatase TiO₂ spheres with equal amount of carbon but different degree of mesoporosity and normal mesoporous TiO₂ are synthesized by solvothermal and sol-gel methods respectively. While the specific surface areas were 80, 35 and 85 m² g^-1 respectively for mesoporous carbon-TiO₂ sphere, carbon-TiO₂ sphere and mesoporous TiO₂, the primary size of the grains constituting the micrometer sized spheres was ∼11 nm. The electrochemical lithium stored by all synthesized TiO₂ materials show strong dependency on mesoporosity and carbon. Mesoporous carbon-TiO₂ sphere exhibited a first discharge cycle capacity of 334 mAh g^-1 at current rate of 66 mAg^-1, whereas carbon-TiO₂ sphere and mesoporous TiO₂ stored 120 and 270 mAh g^-1 respectively. Demonstration of high lithium storage capacity and good cyclability in mesoporous carbon-TiO₂ sphere is attributed to the synergy of mesoporosity and in situ grown carbon in the formation of an effective percolation network for the conducting species (Li+/e−) around TiO2 nanoparticles.