Defective TiO<sub>2</sub>-Supported Dual-Schottky Heterostructure Boosts Fast Reaction Kinetics for High Performance Lithium-Ion Storage
Mengmeng Zhang, Aijiang Lu, Hui Li, Mai Li, Jiale Wang, Chunrui Wang
Abstract
TiO 2, 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-TiO 2 -supported Co-nanodots-anchored N-doped-carbon-coated (defective TiO 2 @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 TiO 2 @Co@NC. And such a Co nanodot can not only firmly bridge the defective TiO 2 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 TiO 2 @Co@NC anode was successfully synthesized via carbonization of the 3D hierarchical defective TiO 2 @Co-MOF precursor. In particular, the defective TiO 2 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 TiO 2 @Co@NC. As expected, defective TiO 2 @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 TiO 2 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 TiO 2 @Co-MOF precursors facilitates the preparation of defective TiO 2 @Co@NC derivatives with tailored specific capacities, which paves the way for future research on MOF composites and Li-ion batteries.