A wearable system based on core-shell structured peptide-Co9S8 supercapacitor and triboelectric nanogenerator

Abstract

We report a new core-shell structure of peptide-Co9S8 nanobricks for supercapacitor electrode. The nanostructured peptide is intrinsically flexible and biocompatible, which is highly suited for wearable supercapacitor electrodes. However, the application of the nanostructured peptide is often limited by its generally low power density and energy density, and its long-term stability is also a concern. Herein, the core-shell structure of peptide-Co9S8 nanobricks is synthesized by conformally coating a thin shell layer of Co9S8 via atomic layer deposition (ALD) onto self-assembled peptide nanobricks. The shell layer can not only protect the peptide material from being attacked by the electrolyte but also contribute extra capacitance to the supercapacitor. The supercapacitors made of the peptide-Co9S8 nanobricks exhibit a high capacitance of 1.3 F/cm2 at 0.7 mA/cm2 and a much improved cycling stability of 96% capacitance retention after 5000 charge-discharge cycling. High-performance flexible solid-state asymmetric supercapacitor (SC) can be also made from the core-shell peptide-Co9S8 nanobricks with activated carbon. The flexible asymmetric supercapacitor can also be coupled with a triboelectric nanogenerator (TENG) to afford a flexible self-powered TENG/SC system. The TENG/SC system with 2.7-h continuously charging by TENG can power a red LED for 21 min, which demonstrates its excellent performance of self-charging and energy-supplying, and therefore it is of great promise for future wearable electronics applications.