Synthesis of anatase TiO2 nanosheets with enhanced pseudocapacitive contribution for fast lithium storage.

Anatase TiO2 nanosheets (ATNs) are successfully prepared by a biomimetic layer-by-layer titania mineralization approach, and the electrochemical performance of the ATNs as negative electrode for lithium-ion batteries is investigated by the galvanostatic chronopotentiometry and cyclic voltammetry. A high initial discharge capacity (311 mA h g(-1)) and initial Coulombic efficiency (81.7%) were obtained for ATNs, and capacities of 252, 202, 186, 158, 136, and 119 mA h g(-1) were obtained at 0.2, 1, 5, 10, 20, and 30 C, respectively. Particularly, the ATNs can still maintains a capacity of 108 mA h g(-1) after 4000 cycles at 30 C (only a capacity loss of 10%), which indicated a superior rate capabilities and cyclability. The CVs analysis revealed that the ANTs have both diffusive lithium storage in the bulk and pseudocapacitive lithium storage at the surface (also called interfacial lithium storage), and the pseudocapacitive lithium storage dominates the total capacity when the scan rates are above 1 mV s(-1). The fast and stable lithium storage of ATNs might be attributed to the high pseudocapacitive lithium storage contribution in the material, and it was suggested the pseudocapacitive lithium storage could occurred at grain-grain interfaces as well as nanosheet surfaces.