Nanoengineering mesoporous graphene-based anatase/bronze TiO2 heterostructures for pseudocapacitance-enhanced lithium-ion batteries

Abstract

As an anode material for lithium-ion batteries, titanium dioxide (TiO2) shows excellent cycling performance. However, the poor rate capacity and low electrical conductivity of TiO2 greatly restrain its application. To improve the slow ion/electron mobility, TiO2 nanosheets with tuned phase compositions and mesoporous structures are being investigated. Here, mesoporous nanosheets with multiple TiO2 phases (anatase/bronze) conformably coated on few-layer graphene (TiO2(AB)@rGO) are synthesized via a one-pot refluxing method followed by freeze drying and heat treatment. This TiO2(AB)@rGO exhibits sheet-like structure constructed of small size (∼10 nm) with high specific surface area (∼165.1 m2 g−1) and uniform mesopore distribution (∼4.0 and 34.5 nm). Consequently, the TiO2(AB)@rGO displays a high specific reversible capacity (300.3 mAh g−1 at 0.17 C) and excellent rate capacity (103.2 mAh g−1 at 7.08 C), which may be attributed to the better ionic/electronic network constructed by hierarchical graphene with superior pseudocapacitive behavior supported by cyclic voltammetry (CV) kinetics analysis. In addition, the mesoporous structure greatly improvs the contact area between electrode and electrolyte, thereby contributing directly to greatly enhanced rate performance.