Ternary systems engineered conductive hydrogel with extraordinary strength, environmental adaptability and excellent electrochemical performances for flexible power supply devices

Abstract

The easy failure, poor environmental adaptability and unsatisfactory electrochemical performances of hydrogels hinder their applications as key components of flexible power supply devices (PSDs). Herein, a PAA-based hydrogel with extraordinary strength and environmental adaptability is designed via a ternary system, consisting of the tannin-modified MXene (TA@MXene), ZnCl2-cellulose and malic acid (MA) electrolyte. The TA@MXene and ZnCl2-cellulose promote the crosslinking of hydrogel via forming multi networks, endowing the hydrogel with 1.9 MPa tensile strength and 620 % stretchability. Furthermore, the hydrogel has 38.4 mS·cm−1 conductivity, thanks to the effective ion transfer channels in the hydrogel. The MA electrolyte provides a stable pH environment via forming an acid ionization system; also, MA and the high-concentration ZnCl2 solution enhance their electrochemical performance at extreme environments. Three typical PSDs were assembled using the resultant hydrogel as electrolyte/electrode. The as-prepared supercapacitors display a high specific capacity (173.5 mAh·g−1), a superior energy density (208.2 Wh·kg−1) and outstanding capacity retention (92.1 % after 5000 cycles); flexible batteries efficiently respond to strain signals, with 0.77 V open-circuit voltage (Voc); the as-assembled TENG has a 110 V Voc (100 % stretching deformation). We present a design strategy for the construction of advanced hydrogels based a ternary system that will promote flexible PSDs towards practical use.