Moving towards high-power, high-frequency and low-resistance CNT supercapacitors by tuning the CNT length, axial deformation and contact resistance

"In this paper it is shown that the electrochemical behaviour of vertically aligned multi-walled. carbon nanotube (VANT) supercapacitors is influenced by the VANTs’ length (electrode. thickness), by their axial compression and by their interface with the current collector. It is. found that the VANTs, which can be interpreted as a dense array of nanochannels, have an. active area available to ions that is strongly affected by the electrode’s thickness and. compressional state. Consequently, the tested thinner electrodes, compressed electrodes or a. combination of the two were found to be characterized by a significant improvement in terms. of power density (up to 1246%), knee frequency (58 822% working up to 10 kHz), equivalent. series resistance (ESR, up to 67%) and capacitance (up to 21%) when compared with thicker. and\/or uncompressed electrodes. These values are significantly higher than those reported in. the literature where long VANTs with no control on compression are typically used. It is also. shown that the ESR can be reduced not only by using shorter and compressed VANTs that. have a higher conductance or by improving the electrode\/collector electrical contact by. changing the contact morphology at the nanoscale through compression, but also by. depositing a thin platinum layer on the VANT tips in contact with the current collector (73%. ESR decrease)"