期刊
JOURNAL OF MATERIALS CHEMISTRY
卷 19, 期 46, 页码 8789-8795出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/b914436f
关键词
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资金
- National Science Foundation [DMI-0455994, DMR-0605159]
- Air Force Office of Scientific Research (AFOSR) [FA9550-06-1-0326]
- Pohang University of Science and Technology, Korea
- University of Washington Center for Nanotechnology (CNT)
- NSF-IGERT [DGE-0654252]
- Chinese Scholarship Council
V2O5 xerogel films were fabricated by casting V2O5 sols onto FTO glass substrates and annealing at 300 degrees C for 3 hours in nitrogen and air. The films annealed in nitrogen and air possessed different grain size and crystallinity. Optical absorption measurements and electrochemical impedance analyses revealed a reduced optical bandgap and enhanced electrical conductivity of N-2 annealed V2O5 film. Lithium ion intercalation measurements showed that at a charge/discharge current density of 600 mAg(-1), the N-2 annealed sample possessed noticeably better lithium ion storage capability. In contrast to the air annealed sample, which started with a discharge capacity of 152 mAhg(-1) but after 50 cycles the capacity had decreased to a low value of only 44 mAhg(-1), the N-2 annealed sample started with a low value of 68 mAhg(-1) but the capacity increased sharply to a high value of 158 mAhg(-1) at the 24(th) cycle, followed by little capacity degradation in later cycles and after 50 cycles, the discharge capacity was still as high as 148 mAhg(-1). Much improved lithium ion intercalation capacity and cyclic stability could be attributed to surface defects V4+ and/or V3+ and associated oxygen vacancies introduced by N-2 annealing as well as much less crystallized vanadium oxide.
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