Spatially confined building of environmental-adaptive hydrogel electrolyte for supercapacitors

Developing hydrogel electrolytes combining enhanced ionic conductivity, great electrolyte/electrode interfacial contact and high electrochemical stability represents the basic demand of flexible electronic devices for cryogenic applications, but is still a formidable challenge at present. Herein, inspired by the antifreeze mechanism of antifreeze proteins (AFP), we developed a facile spatially confined strategy to stabilize water in molecular level so as to prevent freezing meanwhile maintain other critical features of hydrogels at subzero temperature. Meriting from unique AFP-mimetic structure, the polyacrylic acid-DMSO hydrogel prepared by rapid one-pot photo-polymerization embodies merits of excellent flexibility, large ionic conductivity, and strong interfacial adhesiveness with almost all types of surfaces at temperature down to -40 degrees C. As-assembled supercapacitor delivers remarkable specific capacitance of 73 F g(-1) at -40 degrees C (similar to 70% of the capacitance at 20 degrees C), 84.5% of capacitance retention after 5000 charge-discharge cycles at -40 degrees C, and 85.8% of capacitance retention after 1000 cycles at an extreme bending angle of 180 degrees and -40 degrees C, evidently manifesting high efficiency/stability toward cyclic charge-discharge operation and structure deformation in cold climates. It is believed that this work will play an exemplary role in designing anti-freezing hydrogel electrolytes for reliable, flexible electronic devices working at extremely cold environments.