Defective TiO2-Supported Dual-Schottky Heterostructure Boosts Fast Reaction Kinetics for High Performance Lithium-Ion Storage

TiO2, as a potential anode for lithium-ion batteries, suffers from low theoretical capacity and inferior reaction kinetics. Herein, we innovatively designed a unique dual-Schottky regulated ternary defective-TiO2-supported Co-nanodots-anchored N-doped-carbon-coated (defective TiO2@Co@NC) electrode, which was expected to possess advanced electrochemical reaction kinetics and increased Li-ion capacity. Molecular mechanics calculations indicated that the isolated cobalt nanodot can be stably formed in defective TiO2@Co@NC. And such a Co nanodot can not only firmly bridge the defective TiO2 matrix and Co-embedded N-doped carbon coating forming a dual-Schottky heterostructure, which boosts the fast reaction kinetics, but also effectively suppress the irreversibility of Li-ion intercalation. Correspondingly, as-designed binder-free defective TiO2@Co@NC anode was successfully synthesized via carbonization of the 3D hierarchical defective TiO2@Co-MOF precursor. In particular, the defective TiO2 nanotube array was for the first time used as nonreactive template to prepare Co-MOF composites. And TEM characterizations revealed that plentiful isolated cobalt nanodots were factually formed in derivative defective TiO2@Co@NC. As expected, defective TiO2@Co@NC electrodes exhibit remarkably high areal capacity (1191.2 μAh cm–2/490.9 mAh g–1 at 100 μA cm–2/41 mA g–1, 2.8 times of the pristine anatase TiO2 anodes), excellent cyclic stability (a capacity fading rate of 0.026% per cycle, at 500 μA cm–2/206.0 mA g–1 for 600 cycles), and superb rate properties (405.0 μAh cm–2/166.9 mAh g–1 at 1000 μA cm–2/412.0 mA g–1). Furthermore, the realization of in situ growth of uniform Co-MOF coatings with controllable thickness in defective TiO2@Co-MOF precursors facilitates the preparation of defective TiO2@Co@NC derivatives with tailored specific capacities, which paves the way for future research on MOF composites and Li-ion batteries.