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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Enhanced Lithium-Ion Intercalation Properties of V2O5 Xerogel Electrodes with Surface Defects
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Enhanced Lithium-Ion Intercalation Properties of V2O5 Xerogel Electrodes with Surface Defects

机译：具有表面缺陷的V2O5干凝胶电极的增强锂离子嵌入性能

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摘要

V2O5 xerogel films were fabricated by casting V2O5 sols onto fluorine-doped tin oxide (FTO) glass substrates and annealing at 300 °C for 3 h in different annealing atmospheres of air and nitrogen. Films prepared in different annealing conditions possess different grain sizes and crystallinity, while the vanadium ion oxidation state also varies, as identified by X-ray absorption spectroscopy. A nitrogen annealing atmosphere induces the presence of defects, such as V~(4+) ions, and associated oxygen vacancies. Thus, the presence of defects, whether on the film surface or in the bulk, can be controlled by using air and nitrogen annealing atmospheres in the proper order. Electrochemical impedance analyses reveal enhanced charge-transfer conductivity in films with more V~(4+) and oxygen vacancies on the film surface, that is, a film annealed, first, for 0.5 h in air and then for 2.5 h in nitrogen. Lithium-ion intercalation measurements show that, at a charge/ discharge current density of 600 mA g~(-1), this film possesses a noticeably better lithium-ion storage capability than films without surface defects. This sample starts with an initial discharge capacity of 139 mA h g~(-1), and the capacity increases slowly to a maximum value of 156 mAh g in the 15th cycle, followed by a mild capacity degradation in later cycles. After 50 cycles, the discharge capacity is still as high as 136 mA h g~(-1) .A much improved lithium-ion intercalation capacity and cyclic stability are attributed to V~(4+) surface defects and associated oxygen vacancies introduced by N2 annealing.
机译：通过将V2O5溶胶浇铸在掺氟的氧化锡（FTO）玻璃基板上，并在空气和氮气的不同退火气氛中于300°C退火3 h，来制备V2O5干凝胶膜。如通过X射线吸收光谱法所鉴定的，在不同退火条件下制备的膜具有不同的晶粒尺寸和结晶度，而钒离子的氧化态也变化。氮退火气氛引起缺陷的存在，例如V〜（4+）离子和相关的氧空位。因此，可以通过以适当的顺序使用空气和氮气退火气氛来控制缺陷的存在，无论是在膜表面上还是在整体中。电化学阻抗分析表明，在膜表面具有更多V〜（4+）和氧空位的膜中，即在空气中先退火0.5 h，然后在氮气中退火2.5 h，膜的电荷转移电导率增强。锂离子嵌入测量表明，在600 mA g〜（-1）的充电/放电电流密度下，该膜比没有表面缺陷的膜具有明显更好的锂离子存储能力。该样品的初始放电容量为139 mA h g〜（-1），在第15个循环中容量缓慢增加至最大值156 mAh g，随后在随后的循环中容量逐渐降低。经过50个循环后，放电容量仍高达136 mA hg〜（-1）。N〜2引入的V〜（4+）表面缺陷和相关的氧空位使锂离子嵌入容量和循环稳定性大大提高。退火。

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