Two-Dimensional Layered Ultrathin Carbon/TiO Nanosheet Composites for Superior Pseudocapacitive Lithium Storage.

Intercalation of carbon nanosheets into two-dimensional (2D) inorganic materials could enhance their properties in terms of mechanics and electrochemistry, but sandwiching these two kinds of materials in an alternating sequence is a great challenge in synthesis. Herein, we report a novel strategy to construct TiO nanosheets into 2D pillar-layer architectures by employing benzidine molecular assembly as pillars. Then, 2D carbon/TiO nanosheet composite with a periodic interlayer distance of 1.1 nm was obtained following a polymerization and carbonization process. This method not only alleviates the strain arising from the torsion of binding during carbonization but also hinders the structural collapse of TiO due to the intercalation of the carbon layer by rational control of annealing conditions. The composite material possesses a large carbon/TiO interface, providing abundant active sites for ultrafast pseudocapacitive charge storage, thus displaying a superior high-rate performance with a specific capacity of 67.8 mAh g at a current density of 12.8 A g based on the total electrode and excellent cyclability with 87.4% capacity retention after 3000 cycles.