Carbon nanotube yarns as strong flexible conductive capacitive electrodes

• Carbon nanotube (CNT) yarn is a new material with many potential applications in electrochemistry
• We show the use of CNT yarns as capacitive electrodes for energy generation from mixing seawater and river water
• CNT yarns can be used as capacitive electrodes and as electron-conducting flexible scaffolds
• CNT yarns can be coated with an ion-exchange membrane and are expected to be stable in aqueous solutions

Carbon nanotube (CNT) yarn, consisting of 23 μm diameter CNT filaments, can be used as capacitive electrodes that are long, flexible, conductive and strong, for applications in energy and electrochemical water treatment. We measure the charge storage capacity as function of salt concentration, and use Gouy–Chapman–Stern theory to describe the data. CNT yarn can also be used as conductive scaffold for the application of a porous activated carbon (AC) layer. We show the potential of CNT yarn for the generation of electrical energy from environmental entropy differences, by coating yarn (both with and without AC coating) with ion-exchange membranes (IEMs) and generating power from the salt concentration difference between river water and seawater. The use of flexible and conductive CNT yarns as capacitive electrodes and electrode scaffolds breaks with the paradigm of planar static electrodes, and opens up a range of alternative designs for electrochemical cells with enhanced performance.

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