Freeze-Resistant and Tough Cellulose-Integrated Conductive Hydrogels for Flexible Supercapacitors and Self-Powered Electronic Devices

Hydrogel electrolytes hold significant promise for flexible and wearable electronics but often suffer from limited ionic conductivity, poor mechanical integrity, and vulnerability to extreme environmental conditions. Herein, a cellulose-integrated conductive hydrogel electrolyte (MCBH-Zn) with outstanding mechanical strength and freeze resistance is reported. The MCBH-Zn hydrogel achieves a high compressive strength of 5.16 MPa and a tensile fracture stress of 312 kPa, enabled by the synergistic effects of a covalently cross-linked polyacrylamide (PAM) network, hydrogen bonding between PAM and cellulose, and coordination interactions between bentonite (BT) and cellulose. Additionally, it delivers excellent ionic conductivity of 88.9 mS cm –1 at room temperature and 27.3 mS cm –1 at −60 °C. Consequently, a flexible solid-state zinc-ion hybrid supercapacitor (MCBH-ZHSC) assembled with MCBH-Zn delivers stable electrochemical behavior across a wide temperature range and maintains a superior capacity retention of 93% after 10,000 cycles at 10.0 A g –1 . Furthermore, the MCBH-Zn-based wearable device demonstrates self-sustained flexibility and efficient energy harvesting and conversion. This work offers a facile strategy for engineering high-performance hydrogel electrolytes tailored for next-generation wearable technologies.