Abstract:

Cr-doped VO₂(B) has been successfully prepared via the hydrothermal method by adding appropriate amount of Cr(NO₃)₃·9H₂O in the process of synthesis. Combined with some characterization methods such as XRD, XPS, FESEM, EDS, FTIR and so on, the influence of different doping amounts on the phase, morphology, and the electrochemical performance of the Cr-doped VO₂(B) sample were investigated. The constant current charge-discharge test result shows that doping appropriate amount of Cr³⁺ can improve the cycling stability and charge-discharge capacity. When the doping amount was 0.49% and the current density was 0.1C, the initial discharge capacity of the sample was up to 282 mA·h·g^-1, about 36 mA·h·g^-1 more than that of the sample with no doping, and still more than 189 mA·h·g^-1 after 50 cycles, the capacity retention was 67%, better than that of the undoped sample (60.6%) significantly. The results of electrochemical impedance spectra (EIS) and cyclic voltammetry (CV) tests showed that the charge transfer impedance resistance and electrochemical polarization of the sample which doping amount was 0.49% decreased greatly, which further demonstrated its excellent electrochemical properties.

Key words: lithium ion battery, cathode material, VO₂(B), chromium doping, hydrothermal, chemical reaction, electrochemistry

摘要：

采用水热反应法，在合成过程中通过向反应体系中添加Cr（NO₃（₃·9H₂O，制备出了Cr掺杂的VO₂（B（。结合XRD、XPS、FESEM、EDS和FTIR等表征手段，研究了不同掺杂量对目标产物物相、结构和形貌的影响。电化学性能研究表明，当掺杂量（原子百分比，下同）为0.49%时，VO₂（B（正极材料具有最佳的可逆容量和循环稳定性，其在电流倍率为0.1C时，样品的首次放电比容量为282 mA·h·g^-1，较未掺杂样品高出36 mA·h·g^-1，50次循环后，其放电比容量仍高达189 mA·h·g^-1，容量保持率为67%，明显优于未掺杂样品（60.6%）。EIS和CV研究显示，当掺杂量为0.49%时，VO₂（B（电荷转移电阻和电化学反应极化明显降低，此进一步诠释了其优异的电化学性能。

关键词: 锂离子电池, 正极材料, VO₂(B), 铬掺杂, 水热, 化学反应, 电化学