Electromechanical stability, electrochemical energy storage, and mechano-electrochemical energy harvesting of carbon nanotube buckles

Compared with the traditional two-or three-dimensional devices, one-dimensional (1D) coiled carbon nanotube (CNT) yarn-based devices can offer several advantages for wearable, downsizing, and implantable applications. However, coiled CNT yarns still exhibit several significant drawbacks, including structural instability. We propose micro-scale CNT buckled core-sheathed fibers with electrochemical multifunctionalities, including electromechanical stability, wearable supercapacitor application, and energy harvesting ability, to overcome the limitations of 1D coiled CNT yarns. These fibers maintain their electrical performance even under high stretchability conditions without any critical resistance change (less than 10%) because of the high stability of the CNT buckles (-600% tensile strain). In addition, these CNT buckled fibers exhibit improved capacitances (higher than those of the non-buckled structures) and can mechano-electrochemically generate electrical energy under a directed tensile strain (open-circuit voltage peak -0.6 mV at 4 Hz and 300% strain). Such multifunctional CNT buckle fibers hold great prospects in numerous applications, including stretchable electrodes, energy storage, and energy harvesting.