Characterization of vacuum-annealed TiNb2O7 as high potential anode material for lithium-ion battery |
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Authors: | Ryoji Inada Tomoya Mori Rei Kumasaka Ryuta Ito Tomohiro Tojo Yoji Sakurai |
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Affiliation: | Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan |
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Abstract: | Electrochemical properties of mixed titanium-niobium oxide TiNb2O7 (TNO) synthesized via vacuum annealing as high potential anode material for lithium-ion batteries were investigated. Crystal structure, size, and morphology are nearly independent of the annealing atmosphere for starting materials but the color of vacuum-annealed TNO (TNO-V) is dark blue while white for the air-annealed one (TNO-A). X-ray photoelectron spectroscopy analysis also indicated that Ti4+ and Nb5+ in TNO are partially reduced into Ti3+ and Nb4+ due to the introduction of oxygen vacancy. Electronic conductivity for TNO-V was around 10−3 S cm−1 at room temperature and much higher than that for TNO-A (=10−11 S cm−1). In electrochemical testing, both TNO-A and TNO-V electrodes showed reversible capacity of 260-270 mAh g−1 at low current density of 0.5 mA cm−2, while at higher current density of 5.0 mA cm−2, TNO-V electrode retained higher reversible capacity of 140 mAh g−1 than that for TNO-A electrode (=80 mAh g−1). The enhancement of intrinsic electronic conductivity greatly contributes to improve the rate performance of TNO. |
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Keywords: | anode material electronic conductivity lithium-ion battery oxygen vacancy TiNb2O7 |
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