本研究中，我們使用平行板電容器量具，鋰嵌入特性Li3VO4負極及活性碳正極行研究。透過X光繞射(XRD)、氣體吸附法(BET)量測電極材料之晶體結構以及表面積。使用循環伏安法(CV)、恆電流充放電、電化學穩定性測試及電化學交流阻抗(EIS)，測量單電極及電容器的電化學性質。
將Li3VO4以電位窗口0.5 ~ 2.0 V預鋰化，將預鋰化至最終電位0.5 V與預鋰化至最終電位2.0 V，再將Li3VO4負極組裝成的鋰離子混合式電容器的比較，可知預鋰化至最終電0.5 V的電位基準線較預鋰化至最終電2 V更接近Li3VO4開始氧化還原的電位1.35 V，可以增加比電容值，因此在電容器的組裝前Li3VO4負極都經過此預鋰化步驟，並且預鋰化至最終電0.5 V。
推估AC / Li3VO4的最佳重量比例介於2~2.5間，所以我們選用四種AC / Li3VO4重量比例(0.5 / 1、1 / 1、2 / 1、3 / 1)作為比較，並得知AC / Li3VO4重量比例為2 / 1有接近理想電容器的放電曲線，在電位窗口3.5 V，當放電電流密度為0.05 A g-1時，得到最大能量密度 49.1 Wh kg-1，比電容值為34.8 F g-1。
循環穩定性測試以AC / Li3VO4重量比例為2 / 1，電位窗口為3.5 V，電流大小為0.2 A g-1，在充放電250圈時電容保留率為78 %，庫倫效率維持在98%以上；在voltage hold測試以電位窗口為3.5 V，電流大小為0.2 A g-1，並為持在高電壓3.5 V共100小時，在第100小時後電容保留率為80 %。

In this study, we implement a test cell of parallel plate configuration, and study the hybrid capacitor with Li3VO4 negative electrode and activated carbon positive electrode. The electrode and capacitor properties are measured with cyclic voltammetry (CV), impedance spectroscopy, galvanostatic charge/discharge experiments for both long-term and short-term measurements. The phase of Li3VO4 is analyzed with X-ray diffraction, and the surface area analysis of AC is performed with nitrogen adsorption.
As the negative electrode, Li3VO4 crystal must be prelithiated before its assembly. And we find that the end potential of prelithiation process, 0.5 or 2.0 V vs. Li/Li+, has subtle effect on the baseline potential of the hybrid capacitor. When the end potential of prelithiation is 0.5 V, the baseline potential comes near the 1.35 V plateau of Li3VO4 crystal and the voltage window shall be exploited more effectively. On the other hand, when the end potential of prelithiation is 2.0 V, a fraction of the voltage window is wasted on the less capacitive region of Li3VO4 crystal, resulting in a smaller cell capacitance.
Based on the measured capacities of two electrodes, we estimate the maximum cell capacitance is obtained by assembling with the AC: Li3VO4 mass ratio between 2.0 ~ 2.5. Hence, we compare the charge/discharge performance of four cells with the AC: Li3VO4 mass ratio, 0.5:1, 1:1, 2:1, 3:1. Indeed, the measurments indicate the charge/discharge curves of 2:1 ratio approach those of the ideal capacitor. The highest energy density being measured is 49.1 Wh kg-1 at 0.05 A g-1 in the voltage window 3.5 V. The cell capacitance is equal to 34.8 F g-1.
In the cycle stability test, we measure the capacitor stability of 2:1 ratio in the 3.5 V voltage window. The capacitance retention is 78 % at the end of 250 galvanostatic charge/discharge cycles, with the coulomb efficiency 98%. Another voltage hold test shows that after 100 h hold at 3.5 V, the capacitance retains 80% of its original value.

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