Bipolar electrochemical capacitors using double-sided carbon nanotubes on graphite electrodes
Bipolar electrochemical capacitors using double-sided carbon nanotubes on graphite electrodes
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DOI：
10.1016/j.jpowsour.2020.227765
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发表时间：
2020-03
影响因子：
9.2
通讯作者：
J. Hansson;Qi Li;A. Smith;Isaac Zakaria;T. Nilsson;Andreas Nylander;L. Ye;P. Lundgren;Johan Liu;P. Enoksson
中科院分区：
文献类型：
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作者：
J. Hansson;Qi Li;A. Smith;Isaac Zakaria;T. Nilsson;Andreas Nylander;L. Ye;P. Lundgren;Johan Liu;P. Enoksson
电化学电容器（EC）是小型化自供电系统的关键推动因素，随着物联网（IoT）的出现，这种系统有望变得无处不在。石墨上的垂直排列碳纳米管（VACNT）有望成为紧凑和低损耗EC的电极。然而，与所有EC一样，工作电压较低，并且更高电压器件的小型化需要双极设计。在本文中，我们展示了一个双极EC使用石墨/VACNTs电极使用焦耳加热化学气相沉积（CVD）装置制造。所构建的EC包含一层双面VACNTs在石墨上作为双极电极。与两个单独器件的串联连接相比，双极EC的体积能量密度提高了22%。对于堆叠更多的双极电极层，设想了更显著的提升。实现的能量增强，而不加重自放电（71.2%的保留1小时后），并在没有牺牲的循环稳定性（96.7%，超过50000次循环），由于VACNTs的均匀生长，从而消除电池不平衡的问题。
The electrochemical capacitor (EC) is a key enabler for the miniaturized self-powered systems expected to become ubiquitous with the advent of the internet-of-things (IoT). Vertically aligned carbon nanotubes (VACNTs) on graphite holds promise as electrodes for compact and low-loss ECs. However, as with all ECs, the operating voltage is low, and miniaturization of higher voltage devices necessitates a bipolar design. In this paper, we demonstrate a bipolar EC using graphite/VACNTs electrodes fabricated using a joule heating chemical vapor deposition (CVD) setup. The constructed EC contains one layer of double-sided VACNTs on graphite as bipolar electrode. Compared to a series connection of two individual devices, the bipolar EC has 22% boost in volumetric energy density. More significant boost is envisaged for stacking more bipolar electrode layers. The energy enhancement is achieved without aggravating self-discharge (71.2% retention after 1 h), and at no sacrifice of cycling stability (96.7% over 50000 cycles) owing to uniform growth of VACNTs and thus eliminating cell imbalance problems.