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

Abstract

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.

Multifunctional TiO2 Nanotube-Matrix Composites with Enhanced Photocatalysis and Lithium-Ion Storage Performances

“…The structure information of various samples was detected by Raman ( Figure 2 ). The Raman spectrum of TiO 2 NT shows five peaks, corresponding to E g , E g , B 1g , A 1g , and E g vibration modes of anatase TiO 2 , which is consistent with the literature [ 28 , 29 , 30 ]. Additionally, the anatase crystal structure of the TiO 2 nanotube was further confirmed by XRD [ 31 , 32 , 33 ] and TEM [ 28 , 33 , 34 ] results ( Figure S4 ).…”

“…The thinning of the double-layer honeycomb structure is mainly due to the corrosion of the double-layer honeycomb structure after long-term (60 min) exposure to the electrolyte (containing F − ) during secondary oxidation process [ 2 , 38 ]. In addition, compared with the TiO 2 NT (20 min)@Au NP composite, the TiO 2 NT (60 min)@Au NP composite has more Au particles anchored on the nanotubes, which may be due to more defects on the TiO 2 nanotubes (60 min) providing more binding sites for the growth of Au nanoparticles [ 30 , 39 ]. The extra defects in TiO 2 NTs (60 min) are also caused by long-term exposure of NTs to corrosive electrolyte (containing F − ) [ 2 , 38 ].…”

“…Consistent with the literature, the addition of gold does not cause additional peaks in the CV curves [ 61 , 62 ]. In addition, there is no typical peak of MoS 2 because of the low content of molybdenum sulfide in the composites [ 22 ], as well as the overlap of the peak positions of MoS 2 and TiO 2 [ 22 , 30 , 53 , 60 ] forming broad peaks. In particular, the anodic peak and cathodic peak of the TiO 2 NT@MoS 2 NS composite moved to 2.7 and 1.2 V, respectively, corresponding to the shift of the voltage plateaus in the galvanostatic charge–discharge curve ( Figure 6 c).…”

Facile Synthesis of Pre-Lithiated LiTiO2 Nanoparticles for Quick Charge and Long Lifespan Anode in Lithium-Ion Batteries

“…In recent years, titanium dioxide (TiO 2 ) has been widely used as a potential alternative anodic material for LIBs due to its abundance, low cost, and environmental friendliness. − Besides, TiO 2 with a high working potential of more than 1.5 V enables safe operation by avoiding Li electroplating at low potential. , In addition, TiO 2 exhibits excellent structural stability during the Li + intercalation/deintercalation. − In fact, TiO 2 is a typical Li + intercalation compound, and its insertion/extraction reaction of Li could be simplified as TiO 2 + x (Li + + e – ) ↔ Li x TiO 2 (0 ≤ x ≤ 1), in which x is the mole fraction of Li + in TiO 2 . , The theoretical maximum capacity of TiO 2 is 335 mA h g –1 at x = 1, which originates from the complete reduction of the Ti 4+ ions to Ti 3+ ions. However, the insertion coefficient x is usually close to 0.5, corresponding to a theoretical capacity of 167.5 mA h g –1 due to the fact that Li + diffusion in orthorhombic Li 0.5 TiO 2 is strictly restricted .…”