Abstract
? 2022 Elsevier B.V.We developed a highly conductive and flexible, anti-freezing sulfonated lignin (SL)-containing polyacrylic acid (PAA) (SL-g-PAA-Ni) hydrogel, with a high concentration of NiCl2. Ni2+ contributes multi-functions to the preparation of the hydrogel and its final properties, such as fast polymerization reaction as a result of the presence of redox pairs of Ni3+/Ni2+ and hydroquinone/quinone, and anti-freezing properties of the hydrogel due to the salt effects of NiCl2 so that at ?20 °C the hydrogel shows similar properties to those at the room temperature. Thanks to the effective coordinations of Ni2+ with catecholic groups and carboxylic groups, as well as the rich hydrogen bonding capacity, the resultant hydrogel possesses excellent mechanical properties. High ionic conductivity (6.85 S·m?1) of the hydrogel is obtained due to the supply of high concentration of Ni2+. Moreover, the ionic solvation effect of NiCl2 in the hydrogel imparts excellent water retention ability, with water retention of ~93 % after 21-day storage. The SL-g-PAA-Ni hydrogel can accurately detect various human motions at ?20 °C. The supercapacitor assembled from SL-g-PAA-Al hydrogel at ?20 °C manifests a high specific capacitance of 252 F·g?1, with maximum energy density of 26.97 Wh·kg?1, power density of 2667 W·kg?1, and capacitance retention of 96.7 % after 3000 consecutive charge-discharge cycles.
NSTL
Elsevier