The research group led by Prof. MA Mingming at the University of Science and Technology of China has developed a supramolecular strategy to prepare conductive hydrogels with outstanding mechanical and electrochemical properties, which are utilized as electrodes for flexible solid-state supercapacitors with high performance. This work has been published in Angewandte Chemie International Edition (DOI: 10.1002/anie.201603417).

Flexible supercapacitors (FSCs) are attracting increasing attention as a potential solution for powering flexible electronics. Most of current FSCs are made by coating a thin layer of rigid electro-active materials on a flexible non-active substrate. In contrast, conducting polymer-based hydrogels are both electro-active and flexible, which are potentially useful to achieve compact FSCs with higher specific capacitances. However, the mechanical properties and cycling stability of current conducting polymer-based hydrogels are relatively low, which limit their applications for FSCs.

To address this challenge, the researchers led by Prof. MA have developed a new strategy to prepare conductive hydrogels with outstanding mechanical and electrochemical properties. The supramolecular assembly of a rigid conductive polymer (polyaniline) with a soft hydrophilic polymer (polyvinyl alcohol) through dynamic boronate bonds yields polyaniline–polyvinyl alcohol hydrogel (PPH), which shows remarkable tensile strength (5.3 MPa) and electrochemical capacitance (928 F g^-1). The flexible solid-state supercapacitor based on PPH provides a large capacitance (306 mF cm^-2 and 153 F g^-1) and a high energy density of 13.6 Wh kg^-1, superior to other flexible supercapacitors. The robustness of the PPH-based supercapacitor is demonstrated by the 100 % capacitance retention after 1000 mechanical folding cycles, and the 90 % capacitance retention after 1000 galvanostatic charge–discharge cycles. The high activity and robustness enable the PPH-based supercapacitor as a promising power device for flexible electronics.

The structure and mechanical strength of the supramolecular hydrogel, and the performance of the flexible supercapacitor (Courtesy of MA Mingming and Angewandte Chemie International Edition)

This work was financially supported by the NSFC and the Recruitment Program of Global Experts. (CAS Key Laboratory of Soft Matter Chemistry, iChEM, School of Chemistry and Materials Science)

Publication link: http://onlinelibrary.wiley.com/doi/10.1002/anie.201603417/full