Development for Materials Providing Breakthrough in Electric Double Layer Capacitor Performance

为了提高双电层电容器（edlc）的性能，我们对电极和电解质材料进行了大量改进。经过我们的努力，我们取得了丰硕的成果：一种基于PVdF-HFP的凝胶电解质已应用于edlc。技术更新，即极薄凝胶电解质膜（厚度约10μm）和电极-电解质界面结的优化，成功地提供了突出的EDLC性能。特别地，当采用极高倍率的充放电电流时，凝胶EDLC的放电电容没有减小，而采用常规有机电解质的EDLC的放电电容却有所减小。这一结果值得注意，因为我们的凝胶EDLC非常薄，如上所述，并且包含通常的活性炭片电极。我们也尝试改进edlc的电极材料。将活性炭电极暴露于氟化或烷氧基硅烷气体产生的冷等离子体中，可以诱导表面官能团的生成，并优化电极界面的孔径分布。这种改性提高了碳电极的速率性能。此外，我们将“碳纳米管片”应用于EDLC电极，将碳纳米管垂直定向在类似地毯堆的铝箔上。研究发现，碳纳米管片电极适合于高速率循环；即使在大电流下，该电极也能提供高电容，以至于使用普通活性炭电极的EDLC的电容变为零。此外，我们还尝试将上述一些技术应用到可充电锂电池系统中。

To enhance the performance of electric double layer capacitors(EDLCs), we attempted to improve electrode and electrolyte material drastically. As a result of the effort, we have got fruitful achievement as follows :A gel electrolyte based on PVdF-HFP has been applied to EDLCs. Technical renewal, i.e., an extremely thin gel electrolyte film(thickness : ca.10μm) and the optimization of electrode-electrolyte interface junction, successfully provided prominent EDLC performance. Especially, when an extremely high rate charge-discharge current was applied to the present gel EDLC, no decrease in discharge capacitance was observed while the corresponding EDLC with a conventional organic electrolyte showed a decrease in the capacitance. This result is noteworthy because our gel EDLC is very thin as described above and contains usual activated carbon sheet electrodes.We have also attempted to improve electrode material for EDLCs. The exposure of activated carbon electrode to cold plasma generated from fluorinated or alkoxysilane gas induced the generation of surface functional groups and the optimization of pore size distribution at an electrode interface. This modification enhanced the rate capability of the carbon electrode. Furthermore, we applied "carbon nanotube sheet", carbon nanotubes oriented vertically on an aluminum foil like carpet pile, to an EDLC electrode. It was found that the carbon nanotube sheet electrode is suitable for a high rate cycling ; the electrode can provide a high capacitance even with a high current in so much that the capacitance of an EDLC with usual activated carbon electrodes becomes zero.In addition, we tried to apply some of the above-mentioned technologies to rechargeable lithium battery systems.