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Title: Tunnel-structured K xTiO 2 nanorods by in situ carbothermal reduction as a long cycle and high rate anode for sodium-ion batteries

Here, the low electronic conductivity and the sluggish sodium-ion diffusion in the compact crystal structure of Ti-based anodes seriously restrict their development in sodium-ion batteries. In this study, a new hollandite K xTiO 2 with large (2 × 2) tunnels is synthesized by a facile carbothermal reduction method, and its sodium storage performance is investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses illustrate the formation mechanism of the hollandite K xTiO 2 upon the carbothermal reduction process. Compared to the traditional layered or small (1 × 1) tunnel-type Ti-based materials, the hollandite K xTiO 2 with large (2 × 2) tunnels may accommodate more sodium ions and facilitate the Na + diffusion in the structure; thus, it is expected to get a large capacity and realize high rate capability. The synthesized K xTiO 2 with large (2 × 2) tunnels shows a stable reversible capacity of 131 mAh g –1 (nearly 3 times of (1 × 1) tunnel-structured Na 2Ti 6O 13) and superior cycling stability with no obvious capacity decay even after 1000 cycles, which is significantly better than the traditional layered Na 2Ti 3O 7 (only 40% of capacity retention in 20 cycles). Moreover, the carbothermalmore » process can naturally introduce oxygen vacancy and low-valent titanium as well as the surface carbon coating layer to the structure, which would greatly enhance the electronic conductivity of K xTiO 2 and thus endow this material high rate capability. With a good rate capability and long cyclability, this hollandite K xTiO 2 can serve as a new promising anode material for room-temperature long-life sodium-ion batteries for large-scale energy storage systems, and the carbothermal reduction method is believed to be an effective and facile way to develop novel Ti-based anodes with simultaneous carbon coating and Ti(III) self-doping.« less
Authors:
 [1] ;  [1] ;  [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Huazhong Univ. of Science and Technology (HUST), Hubei (People's Republic of China)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-113637-2017-JA
Journal ID: ISSN 1944-8244; R&D Project: 16060; 16060; KC0403020; TRN: US1700888
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 8; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
29 ENERGY PLANNING, POLICY, AND ECONOMY; sodium ion batteries; anode; hollandite; carbothermal reduction; tunnel structure; long cycle; high rate; Center for Functional Nanomaterials
OSTI Identifier:
1347366