Stable Flexible Electronic Devices under Harsh Conditions Enabled by Double-Network Hydrogels Containing Binary...

Hydrogels are increasingly used in flexible electronic devices, but the mechanical and electrochemical stabilities of hydrogel devices are often limited under specific harsh conditions. Herein, chemically/physically cross-linked double-network (DN) hydrogels containing binary cations Zn²⁺ and Li⁺ are constructed in order to address the above challenges. Double networks of chemically cross-linked polyacrylamide (PAM) and physically cross-linked κ-Carrageenan (κ-CG) are designed to account for the mechanical robustness while binary cations endow the hydrogels with excellent ionic conductivity and outstanding environmental adaptability. Excellent mechanical robustness and ionic conductivity (25 °C, 2.26 S·m^-1; -25 °C, 1.54 S·m^-1) have been achieved. Utilizing the DN hydrogels containing binary cations as signal-converting materials, we fabricated flexible mechanosensors. High gauge factors (resistive strain sensors, 2.4; capacitive pressure sensors, 0.82 kPa^-1) and highly stable sensing ability have been achieved. Interestingly, zinc-ion hybrid supercapacitors containing the DN hydrogels containing binary cations as electrolytes have achieved an initial capacity of 52.5 mAh·g^-1 at a current density of 3 A·g^-1 and a capacity retention rate of 82.9% after 19,000 cycles. Proper working of the zinc-ion hybrid supercapacitors at subzero conditions and stable charge-discharge for more than 19,000 cycles at -25 °C have been demonstrated. Overall, DN hydrogels containing binary cations have provided promising materials for high-performance flexible electronic devices under harsh conditions.