Dandelion-shaped TiO2/multi-layer graphene composed of TiO2(B) fibrils and anatase TiO2 pappi utilizing triphase boundaries for lithium storage

Abstract

A three-dimensional dandelion-shaped TiO<inf>2</inf>/multi-layer graphene compound (TiO<inf>2</inf>/MLG) composed of TiO<inf>2</inf>(B) fibrils and anatase pappus structures has been synthesized as a potential anode material for Li storage. Electron microscopy indicates that the composite contains triphase boundaries between anatase, TiO<inf>2</inf>(B) and graphene, which are responsible for the enhancement of energy storage and the decrease of electrode polarization. Cyclic voltammetric investigations indicate that both Li⁺ insertion and pseudocapacitance contribute to charge storage. Ultrahigh specific capacities of 243 and 182 mA h g^-1 have been obtained at 0.1 and 1 A g^-1, respectively. Moreover, the excellent capacity retention can reach 99.6% after 100 cycles with almost 100% coulombic efficiency at 0.1 A g^-1. The importance of the triphase boundary in enhancing the storage of charge and transport of Li⁺ is demonstrated.