Enhancing lithium and sodium storage properties of tio2(B) nanobelts by doping with nickel and zinc

Abstract

Nickel‐ and zinc‐doped TiO2(B) nanobelts were synthesized using a hydrothermal technique. It was found that the incorporation of 5 at.% Ni into bronze TiO2 expanded the unit cell by 4%. Furthermore, Ni dopant induced the 3d energy levels within TiO2(B) band structure and oxygen defects, narrowing the band gap from 3.28 eV (undoped) to 2.70 eV. Oppositely, Zn entered restrict-edly into TiO2(B), but nonetheless, improves its electronic properties (Eg is narrowed to 3.21 eV). The conductivity of nickel‐ (2.24 × 10−8 S∙cm−1) and zinc‐containing (3.29 × 10−9 S∙cm−1) TiO2(B) ex-ceeds that of unmodified TiO2(B) (1.05 × 10−10 S∙cm−1). When tested for electrochemical storage, nickel‐doped mesoporous TiO2(B) nanobelts exhibited improved electrochemical performance. For lithium batteries, a reversible capacity of 173 mAh∙g−1 was reached after 100 cycles at the current load of 50 mA∙g−1, whereas, for unmodified and Zn‐doped samples, around 140 and 151 mAh∙g−1 was obtained. Moreover, Ni doping enhanced the rate capability of TiO2(B) nanobelts (104 mAh∙g−1 at a current density of 1.8 A∙g−1). In terms of sodium storage, nickel‐doped TiO2(B) nanobelts exhibited improved cycling with a stabilized reversible capacity of 97 mAh∙g−1 over 50 cycles at the current load of 35 mA∙g−1.