CNT-functionalized electrospun fiber mat for a stretchable moisture-driven power generator

Abstract

With recent demand for next-generation wearable and stretchable electronics, development of reliable power systems that can accommodate the flexibility and stretchability of devices is necessary. Recently, a moisture-driven power generator (MPG) has been considered as one of the powerful candidates for providing energy to the next-generation wearable and stretchable devices. However, so far, currently developed MPG systems do not meet the stretchability requirements. Here, we report a stretchable MPG formed by layer-by-layer coating of carbon nanotubes on a stretchable electrospun fiber mat. By adding water to the stretchable MPG, an electrical double layer is developed at the interface between the carbon nanotubes and water. Transport of protons (H₃O⁺) in water induces the movement of electrons in the carbon nanotubes, inducing a pseudostreaming current. The MPG of 1 cm × 2 cm with 10 μL of deionized water generates a maximum open-circuit voltage (V_OC) of 419 mV, a maximum short-circuit (I_SC) current of 1.5 μA, and a maximum power output of 320 nW, depending on the loading of the carbon nanotubes. In addition, 0.6 M NaCl solution enhances the generated V_OC (∼800 mV), maximum I_SC (13 μA), and maximum power output of 10.4 μW by supplying additional Na⁺ ions to the carbon nanotube surface and reducing the resistance of the device, respectively. Furthermore, MPG can generate a V_OC of 600 mV and an I_SC of 0.7 μA even when stretched with a strain of 60%. The MPG reported here has the potential to be used as a reliable power generator for wearable and stretchable electronic devices.