Core‐Shell Se‐Doped TiO₂@Carbon Nanotubes for High‐Performance Sodium‐Ion Batteries

Abstract

Titanium dioxide (TiO2) has been considered as a promising anode material for sodium‐ion batteries (SIBs), because of its abundance, safety and eco‐friendliness. However, the inferior electronic conductivity and low sodium ion diffusion rate of TiO2 hinder its improvement of electrochemical performance. To overcome these drawbacks, herein, core‐shell Se‐doped TiO2@carbon nanotubes (denoted as Se‐TiO2@CNTs) are successfully designed and fabricated, in which the TiO2 nanoparticle aggregated shells are conformally coated on the carbon nanotubes, while the metallic Se species are physically confined within the meso/micropores. When examined as a SIB anode, the Se‐TiO2@CNTs electrode demonstrates excellent sodium storage performance, correspondingly delivering high reversible capacities of 222.7/208.5 mA h g−1 after 200/1000 cycles at current densities of 0.2/1.0 A g−1, and even a capacity of 140.2 mA h g−1 after 4500 cycles at a high‐rate of 5.0 A g−1. The high reversible capacity, long‐term cycling stability, and high‐rate capability of the Se‐TiO2@CNTs can be owing to the unique structure characteristics, as the hollow/porous structure with high specific surface area of 335.4 m2 g−1 efficiently shortens the Na+ diffusion length and facilitates the electrolyte penetration, while Se‐doping and carbon supporting greatly enhance the electronic conductivity of the Se‐TiO2@CNTs electrode.

Ultrafine Sb2O3 Nanoparticle-Decorated Reduced Graphene Oxide as an Anode Material for Lithium-Ion Batteries

“…The kinetics and mechanism of lithium storage in the Sb 2 O 3 /rGO electrode were further analyzed by electrochemical impedance spectroscopy (EIS). Figure c shows the EIS spectra of Sb 2 O 3 /rGO-100, Sb 2 O 3 /rGO-200, and Sb 2 O 3 before cycling, where the diameter of the semicircle in the high-frequency region represents the charge transfer resistances R ct , while the sloping line in the low-frequency region corresponds to the ions diffusion ability . Apparently, Sb 2 O 3 /rGO-100 (133.51 Ω) shows a smaller R ct than Sb 2 O 3 /rGO-200 (157.94 Ω) and Sb 2 O 3 (218.59 Ω), which is attributed to the porous network structure of the Sb 2 O 3 /rGO-100 composite providing a faster transfer channel for electron.…”

Encapsulating Sb/MoS2 Into Carbon Nanofibers Via Electrospinning Towards Enhanced Sodium Storage

“…To this end, many efforts have been made to develop high‐performance anode materials, including intercalation‐type hard carbon/oxides (e. g., TiO 2 ), [8–10] hybrid‐type metal chalcogenides (e. g., MoS 2 ), [11] conversion‐type metal oxides/chalcogenides (e. g., CoSe 2 ), [12] alloy‐type metals/metal oxides (e. g., Sb, SnO 2 ) [9,13,14] . Among these candidates, MoS 2 and metallic Sb have been identified as promising anode materials for SIBs [9,11,13] .…”

Defect-Induced and Synergistic Na-Ion Storage Capability of TiO2(B)@MoSe2/Carbon Trinity for Ultrafast and Ultralong Cycling

“…However, the practical capacity of TiO 2 (B) for Na + storage is still not high enough, and its semiconductive characteristic also hinders the rate performance. Some strategies such as heteroatom doping or incorporation of carbon into TiO 2 (B) have been adopted to improve its performance. − Yang et al reported the synthesis of N-doped TiO 2 (B) nanorods, which exhibited a higher specific capacity of 224.5 mAh g –1 and enhanced rate capability (110 mAh g –1 at 3.35 A g –1 ) as compared with anatase TiO 2 and undoped TiO 2 (B) . Huo et al prepared nanowire-like TiO 2 (B)/carbon nanocomposites, which also exhibited improved performance as the anode material of SIBs .…”