Nanowires based solid-state asymmetric self-charging supercapacitor driven by PVA–ZnO–KOH flexible piezoelectric matrix

Abstract

The development of an efficient mechanical to electric energy conversion system and its functional integration with an energy storage device for self-powered portable devices are advanced research fields. In the traditionalconfiguration, an additional energy harvesting device is connected with an energy storage device for developing a self-charging unit. As a result, large amount of energy is lost because of the external rectifiers. Moreover, this type of external circuit makes the system bulky and thus, limits the practical applications of such devices. In this work, nanoparticles of Zinc oxide (ZnO) are employed as a piezoelectric material, and are combined with an asymmetric device for developing a self-charging asymmetric piezo-supercapacitor. The developed asymmetric piezo-supercapacitor comprises of Ni and Mg-Co nanowires-based binder-free electrodes that were employed as the anode and cathode, respectively, as well as a ZnO-based separator as energy harvester along with KOH as electrolyte. The electrochemical results reveal tremendous cyclic stability with capacitive retention of 100% and 96.5% for Mg-Co and Ni nanowires array based electrodes even after 10,000 repeated GCD cycles, respectively. In addition, the device attained a maximum voltage of ∼99 mV as a result of the compressive force via thumb press. The proposed facile as well as cost-effective approach for smart self-chargeable power package supercapacitor provides new insights for developing next generation all-in-one energy harvesting and storage devices.