Prestretching-Enhanced Conductive Hydrogel Electrode for Supercapacitors with High Areal Capacitance and Excellent Stretching Stability

The challenge to prepare conductive hydrogel electrodes for stretchable supercapacitors with high areal capacitance and excellent stability during stretching has attracted tremendous attention from researchers. Herein, a method to enhance the performance of a conductive hydrogel electrode is reported. The in situ oxidative polymerization of aniline monomer is performed in the prestretched polyacrylamide (PAAm) hydrogel. After releasing the hydrogel, the polyaniline (PANI) nanoparticles can shrink with the PAAm substrate to form a dense and continuous conductive network. Due to the enhanced conductive networks, the prestretched PAAm-PANI conductive hydrogel with prestrain of 500% (PPCH5) electrode shows high areal capacitance of 509.9 mF cm(-2) at 0.5 mA cm(-2). The symmetrical stretchable supercapacitor based on PPCH5 electrodes exhibits a high areal capacitance of 219.7 mF cm(-2). The device shows high capacitance retention of 68.5% even when stretched to 200% strain and noncapacitance decays after 2000 stretching cycles at 100% strain. This strategy can be expanded to the carbon nanotubes (CNT)-filled hydrogel systems. The PAAm-PANI-CNT conductive hydrogel with prestrain of 500%-based supercapacitor shows specific capacitance of 1429.87 mF cm(-2). The results demonstrate that prestretching is a highly effective method to enhance capacitance and stretching stability of PANI hydrogel electrode for stretchable supercapacitors.