Mechanically Strong, Freeze-Resistant, and Ionically Conductive Organohydrogels for Flexible Strain Sensors and Batteries.

ABSTRACT

Conductive hydrogels as promising material candidates for soft electronics have been rapidly developed in recent years. However, the low ionic conductivity, limited mechanical properties, and insufficient freeze-resistance greatly limit their applications for flexible and wearable electronics. Herein, aramid nanofiber (ANF)-reinforced poly(vinyl alcohol) (PVA) organohydrogels containing dimethyl sulfoxide (DMSO)/H2 O mixed solvents with outstanding freeze-resistance are fabricated through solution casting and 3D printing methods. The organohydrogels show both high tensile strength and toughness due to the synergistic effect of ANFs and DMSO in the system, which promotes PVA crystallization and intermolecular hydrogen bonding interactions between PVA molecules as well as ANFs and PVA, confirmed by a suite of characterization and molecular dynamics simulations. The organohydrogels also exhibit ultrahigh ionic conductivity, ranging from 1.1 to 34.3 S m-1 at -50 to 60 °C. Building on these excellent material properties, the organohydrogel-based strain sensors and solid-state zinc-air batteries (ZABs) are fabricated, which have a broad working temperature range. Particularly, the ZABs not only exhibit high specific capacity (262 mAh g-1 ) with ultra-long cycling life (355 cycles, 118 h) even at -30 °C, but also can work properly under various deformation states, manifesting their great potential applications in soft robotics and wearable electronics.