Sulfur-Doped Anatase TiO₂ as an Anode for High-Performance Sodium-Ion Batteries

Abstract

Sulfur-doped anatase TiO2 was prepared through a calcination conversion route for the first time. The grain size of TiO2 with S-doping obviously decreased after S-doping, manifesting that the introduction of S species could inhibit the crystal growth. Applied as an anode material for sodium-ion batteries, this material exhibited an impressive specific capacity of 174.4 mA h g–1 at a high current density of 10 C after 10 000 cycles. The remarkable performance results from the unique crystal structure of anatase TiO2 with bidirectional pore channels for sodium-ion intercalation, and S-doped TiO2 could increase the electronic conductivity, as well as enlarge the channel structure. Furthermore, density functional theory calculations manifested that the S-doping increases the volume of the lattice slightly, leading to the ease of insertion for sodium ions into anatase TiO2 and a reduced band gap with higher electronic conductivity. Therefore, S-doped TiO2 showed high reversible capacities and excellent long-term cycling performance.

Oxygen Vacancy Engineering in Titanium Dioxide for Sodium Storage

“…Similarly, non‐metallic (B, [50] N, [51] P, [5] S, [52] etc.) doping has also been found to be an effective way to replace O atoms or occupy the interstitial positions in TiO 2 lattices, forming impurity energy levels and creating OVs.…”

“…prepared sulfur‐doped anatase TiO 2 by calcination (Figure 6b), which exhibited impressive long‐term cycling performance when used as a SIBs anode (Figure 6c). The remarkable performance was attributed to the enhanced electronic conductivity and enlarged channel structure [52] . Although S doping showed a bandgap narrowing, it would be difficult for S atoms to deeply incorporate into the TiO 2 crystal because of its large ionic radius, as evidenced by much larger formation energy for substitution.…”

“…(b) schematic illustration for the preparation of S−TiO 2 , (c)cycling performance at 10 C for 10 000 cycles. Reprinted with permission from Ref [52] . Copyright 2019 American Chemical Society.…”

Multiple Active Sites Carbonaceous Anodes for Na+ Storage: Synthesis, Electrochemical Properties and Reaction Mechanism Analysis

“…[ 37 ] Various reports have demonstrated that once the carbon interlayer distance exceeds 0.37 nm, the Na ions are easy to insert into carbon layer and achieve reversible capacity. [ 95,96 ] The first relative work could retrospect to 2011, [ 97 ] Schmidt and co‐workers fabricated microporous S‐doped carbon with a high S content (5–23 wt%) and large specific surface area (711 m 2 g −1 ) derived from thienyl‐based polymer precursors. Generally, S doping is in favor of enlarging carbon interlayer distance, decreasing Na diffusion barrier and participating in conversion reaction, but just slightly promoting the Na adsorption and easily causing structural deformation during long‐term cycling, corresponding to higher Na storage capacity but poor cycling stability.…”

Nitrogen-doped carbon encapsulated in mesoporous TiO2 nanotubes for fast capacitive sodium storage

“…TiO 2 with various nanostructures such as nanofibers [20], nanorods [21], nanopills [22], nanocrystals [23], and nanosheets [24] has been widely investigated as an anode material for SIBs. Another efficient approach to improve the sodium storage performance of TiO 2 is heteroatom doping (N, S, or B) [25][26][27]. In addition, combining TiO 2 with conductive carbon materials (such as graphene) can improve its electronic conductivity, and hence electrochemical performance.…”