Polyaniline hydrogel anchored in carbon cloth network to support Co(OH)2 as flexible electrode for high-energy density supercapacitor

A versatile, highly stretchable, and anti-freezing alginate/polyacrylamide/polyaniline multi-network hydrogel for flexible strain sensors and supercapacitors

Conductive hydrogels have great potential as electrolyte materials for flexible strain sensors and supercapacitors. However, it remains a challenge to develop multifunctional hydrogels with excellent frost resistance, toughness, ionic conductivity, and electrochemical properties using simple methods. Herein, a "chemical-physical-ionic" cross-linked sodium alginate/polyacrylamide/polyaniline (SA/PAM/Ca2+/PANI) multi-network hydrogel was developed by in situ polymerization of aniline monomer within a Ca2+-crosslinked SA/PAM hydrogel network. The SA/PAM/Ca2+/PANI hydrogel shows excellent mechanical properties, (tensile strength of 0.577 MPa at a strain of 1991 %), high toughness (5.52 KJ·m-3), and high ionic conductivity (16.51 S·m-1 at 25 °C and 11.08 S·m-1 at -20 °C). The SA/PAM/Ca2+/PANI hydrogel-based strain sensor exhibited high sensitivity (gauge factor of 3.82 at 60-500 % strain), an extensive detection range (0-2000 %), and excellent frost resistance. The strain sensor can accurately monitor various human motions, as well as electrocardiograph (ECG) signals during both rest and exercise. The supercapacitor assembled with the SA/PAM/Ca2+/PANI hydrogel electrolyte exhibited a high surface capacitance (177.19 mF·cm-2 at 2 mA·cm-2), maximum energy density (21.93 Wh·kg-1), and high power density (3089 W·kg-1). Moreover, it maintained satisfactory electrochemical stability with 77.8 % capacitance retention after 4000 cycles. Therefore, the versatile SA/PAM/Ca2+/PANI hydrogel shows promising potential for applications in flexible wearable electronic devices.

Conducting polymer hydrogels as a sustainable platform for advanced energy, biomedical and environmental applications

Environmentally friendly polymeric materials and derivative technologies play increasingly important roles in the sustainable development of our modern society. Conducting polymer hydrogels (CPHs) synergizing the advantageous characteristics of conventional hydrogels and conducting polymers are promising to satisfy the requirements of environmental sustainability. Beyond their use in energy and biomedical applications that require exceptional mechanical and electrical properties, CPHs are emerging as promising contaminant adsorbents owing to their porous network structure and regulable functional groups. Here, we review the currently available strategies for synthesizing CPHs, focusing primarily on multifunctional applications in energy storage/conversion, biomedical engineering and environmental remediation, and discuss future perspectives and challenges for CPHs in terms of their synthesis and applications. It is envisioned to stimulate new thinking and innovation in the development of next-generation sustainable materials.