Two Dimensional Layered Ultrathin Carbon/TiO2 Nanosheets Composite 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 alternating sequence is a great challenge on synthesis. Herein, we report a novel strategy to construct TiO2 nanosheets into 2D pillar-layer architectures by employing benzidine molecular assemble as pillars. Then the 2D carbon/TiO2 nanosheets composite with a periodic interlayer distance of 1.1 nm was obtained following a polymerization and carbonization. This method not only alleviates the strain arisen from the torsion of binding during the carbonization, but also hinders the structural collapse of TiO2 due to the intercalation of carbon layer by rational control of annealing conditions. The composite material possesses a large carbon/TiO2 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 the current of 12.8 A/g based on the total electrode and excellent cyclability with 87.4 % capacity retention after 3000 cycles.