High Pseudocapacitance Boosts Ultrafast, High-Capacity Sodium Storage of 3D Graphene Foam-Encapsulated TiO Architecture.

Anatase TiO is an attractive anode for Li-ion batteries and Na-ion batteries because of its structural stability. However, the electrochemical capability of anatase TiO is unsatisfactory due to its intrinsically low electrical conductivity and poor ion diffusivity at the electrode/electrolyte interface. We prepared 3D lightweight graphene aerogel-encapsulated anatase TiO, which exhibits a high reversible capacity (390 mA h g at 50 mA g), a superior rate performance (164.9 mA h g at 5 A g), and a long-term cycling capability (capacity retention of 86.8% after 7800 cycles). The major energy-storage mechanism is surface capacitance dominated, which favors a high capacity and fast Na uptake. The inherent features of 3D porous aerogels provide additional active reaction sites and facilitate fast charge diffusion and easy ion access. This will enable the development of 3D interconnected, graphene-based, high-capacity active materials for the development of next-generation energy-storage applications.