V2O5 xerogel electrodes with much enhanced lithium-ion intercalation properties with N2 annealing
V2O5 xerogel electrodes with much enhanced lithium-ion intercalation properties with N2 annealing
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DOI：
10.1039/b914436f
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发表时间：
2009-01-01
影响因子：
--
通讯作者：
Cao, Guozhong
中科院分区：
文献类型：
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作者：
Liu, Dawei;Liu, Yanyi;Cao, Guozhong
V2O5 干凝胶薄膜的制备方法是将 V2O5 溶胶浇注到 FTO 玻璃基板上，并在氮气和空气中于 300 摄氏度下退火 3 小时。在氮气和空气中退火的薄膜具有不同的晶粒尺寸和结晶度。光吸收测量和电化学阻抗分析表明，N-2 退火 V2O5 薄膜的光学带隙减小，电导率增强。锂离子嵌入测量表明，在充放电电流密度为600 mAg(-1)时，N-2退火样品具有明显更好的锂离子储存能力。空气退火样品开始时放电容量为152 mAhg(-1)，但经过50次循环后容量下降至仅44 mAhg(-1)的低值，而N-2退火样品开始时放电容量为68 mAhg(-1)，但在第24次循环时容量急剧增加至158 mAhg(-1)的高值，随后容量几乎没有下降。在以后的循环和50次循环后，放电容量仍然高达148mAhg(-1)。大大提高的锂离子嵌入能力和循环稳定性可归因于表面缺陷V4+和/或V3+以及由N-2退火引入的相关氧空位以及结晶更少的氧化钒。
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.