Co‐doping Nitrogen/Sulfur through a Solid‐State Reaction to Enhance the Electrochemical Performance of Anatase TiO₂ Nanoparticles as a Sodium‐Ion Battery Anode

Abstract

Nitrogen‐ and/or sulfur‐doping has been used to enhance the electrochemical performance of TiO2 anodes in lithium‐ion batteries. Multiple doping in one step presents a challenge to produce anodes with excellent performance. Herein, we reports a facile process to co‐dope nitrogen and sulfur into black anatase TiO2 nanoparticles accomplished by using a solid‐state reaction with dried TiO2 gel and thiourea. Co‐doping introduced N and S atoms into the TiO2 matrix, increasing oxygen vacancies, thus enhancing the intrinsic electronic conductivity. Co‐doping also decreased the size of TiO2 nanoparticles from 15.6 to 10.1 nm, and increased the surface area from 77 to 129 m2 g−1, facilitating insertion/extraction of Na ions during charge‐discharge cycling. N/S co‐doped TiO2 exhibited a signficantly higher performance as a sodium‐ion battery anode than pristine black TiO2. The rate performance of the co‐doped TiO2 is improved up to 80 % in comparison with pristine black TiO2.

Pseudocapacitive Na+ Insertion in Ti–O–C Channels of TiO2–C Nanofibers with High Rate and Ultrastable Performance

“…The much broader peaks of N/S–TO–C indicate further decreased crystallite size of TiO 2 owing to N/S co-doping. The uniform dispersion of smaller TiO 2 nanoparticles in carbon may increase TiO 2 –C interfaces and provide more accessible Ti–O–C channels for Na + storage. , Elemental analysis was involved to show that the contents of C, N, and S elements in N/S–TO–C are around 10.98, 8.16, and 2.28%, respectively. In addition, TG (Figure S1) demonstrates that the mass ratio of TiO 2 is about 73%, corresponding to elemental analysis results.…”

High Pseudocapacitance Boosts Ultrafast, High-Capacity Sodium Storage of 3D Graphene Foam-Encapsulated TiO2 Architecture

“…Extensive research has been carried out to address the issues of TiO 2 anodes. Heteroatom doping (e.g., Nb, Co, and Mo to replace Ti 4+ or N and S to replace O 2– ) is an effective method for improving the intrinsic electronic conductivity. , Introduction of defects via foreign donor atoms, oxygen defects, or Ti 3+ during TiO 2 reduction effectively narrows the band gap and further improves the intrinsic electrical conductivity. , Yu et al synthesized graphene sheets-supported sulfur-doped anatase TiO 2 nanosheets (S-TiO 2 /rGO) and obtained a high capacity of 153 mA h g –1 at a high rate of 20 C . Sulfur doping endows S-TiO 2 /rGO with large numbers of Ti 3+ /oxygen vacancy defects, which contribute to pseudocapacitive Na + storage at high rates.…”

High Power Sodium-Ion Batteries and Hybrid Electrochemical Capacitors Using Mo or Nb-Doped Nano-Titania Anodes

“…6 Possible active materials for NIB negative electrodes include hard carbons, 7,8 alloying materials such as Sn/carbon composites, 9,10 conversion materials such as NiCo 2 O 4 , 11 as well as titanium-based insertion materials. The various polymorphs of TiO 2 have received a great deal of attention, including amorphous nanotubes, 12,13 TiO 2 (B), 14,15 rutile, 5 Nb-doped, 16 N/S co-doped, 17 as well as undoped anatase TiO 2 . 4,6 One of the disadvantages of LIBs and NIBs is their typically inferior performance at high power compared with supercapacitors.…”