Functionalized carbon nanotube based hybrid electrochemical capacitors using neutral bromide redox-active electrolyte for enhancing energy density
Functionalized carbon nanotube based hybrid electrochemical capacitors using neutral bromide redox-active electrolyte for enhancing energy density
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DOI：
10.1016/j.jpowsour.2017.03.094
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发表时间：
2017-06
影响因子：
9.2
通讯作者：
Xiaohui Tang;Y. Lui;Bolin Chen;Shan Hu
中科院分区：
文献类型：
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作者：
Xiaohui Tang;Y. Lui;Bolin Chen;Shan Hu
通过将功能化碳纳米管（FCNT）电极与具有中性pH值的氧化还原活性电解质（1 M Na 2SO 4和0.5 M KBr混合水溶液）集成，实现了具有增强的能量密度的混合电化学电容器（EC）。负电极显示出双电层电容器型行为。在正极上，发生高度可逆的Br−/Br 3 −氧化还原反应，呈现电池型行为，这有助于增加混合电池的电容。整个电池的电压窗口扩展到1.5 V，因为在中性电解质中的析氧和析氢反应的高过电位。与未处理的碳纳米管相比，碳纳米管在电解液中具有更好的润湿性，有助于提高电池的双电层电容。结果，混合EC在0.5 A g-1下获得28.3 Wh kg-1的最大能量密度，而不牺牲其功率密度，这是由FCNT电极和1 M Na 2SO 4电解质构成的双电层电容器的约4倍。此外，在10000次恒电流充放电试验（10 A/g）后，放电容量仍保持其初始性能的86.3%，表明其即使在高电流负载下也具有长寿命。
A hybrid electrochemical capacitor (EC) with enhanced energy density is realized by integrating functionalized carbon nanotube (FCNT) electrodes with redox-active electrolyte that has a neutral pH value (1 M Na2SO4and 0.5 M KBr mixed aqueous solution). The negative electrode shows an electric double layer capacitor-type behavior. On the positive electrode, highly reversible Br−/Br3−redox reactions take place, presenting a battery-type behavior, which contributes to increase the capacitance of the hybrid cell. The voltage window of the whole cell is extended up to 1.5 V because of the high over-potentials of oxygen and hydrogen evolution reactions in the neutral electrolyte. Compared with raw CNT, the FCNT has better wettability in the aqueous electrolyte and contributes to increase the electric double layer capacitance of the cell. As a result, the maximum energy density of 28.3 Wh kg−1is obtained from the hybrid EC at 0.5 A g−1without sacrificing its power density, which is around 4 times larger than that of the electrical double layer capacitor constructed by FCNT electrodes and 1 M Na2SO4electrolyte. Moreover, the discharge capacity retained 86.3% of its initial performance after 10000 cycles of galvanostatic charge and discharge test (10 A/g), suggesting its long life cycle even at high current loading.