An asymmetric capacitor of internal parallel hybrid electrodes with amphoteric lithium vanadium phosphate
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- 作者：Ying-Chen Liao ; Dah-Shyang Tsai ; Yu-Sheng Huang…
- 关键词：Asymmetric capacitor ; Lithium vanadium phosphate ; Internal parallel hybridization ; Prelithiation ; Mass balancing ; Activated carbon
- 刊名：Journal of Solid State Electrochemistry
- 出版年：2017
- 出版时间：March 2017
- 年：2017
- 卷：21
- 期：3
- 页码：839-847
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Physical Chemistry; Electrochemistry; Energy Storage; Characterization and Evaluation of Materials; Analytical Chemistry; Condensed Matter Physics;
- 出版者：Springer Berlin Heidelberg
- ISSN：1433-0768
- 卷排序：21
文摘
Given that the amphoteric Li3V2(PO4)3 (LVP) crystal exhibits different capacities in the high and low potential regions, we study its asymmetric capacitor and the mass balancing. Both the positive and the negative electrodes are prepared with 50 wt.% LVP balanced by activated carbon which provide battery and double-layer storage mechanisms; respectively. To retain the capacitor power feature with a sizable capacity, a proper internal hybridization is required to keep the battery mechanism functioning at high-rate cycling. The involvement of battery storage is assured if a high-voltage bulge is observed on the galvanostatic discharge curve. To preserve such a feature, the capacitor analysis indicates three factors are vital. A voltage window is wide enough, 4.0 V, such that the plateau of LVP around 3.6 V (vs. Li/Li+) may operate in discharging the positive electrode. The negative electrode is prelithiated to pin down the negative potential and allow the cell to utilize the permissible potential window. A proper mass ratio 2(+):1(−) provides sufficient but not too much battery storage in the positive electrode. Among the five mass ratios being studied, the 2(+):1(−) capacitor shows a respectable combination of specific energy 43 W h kg−1 and power 520 W kg−1 at 0.2 A g−1, with over 80 % capacity retention in 200 cycles.