Electrochemically building three-dimensional supramolecular polymer hydrogel for flexible solid-state micro-supercapacitors

Conducting polymer hydrogels (CPHs) advantageously synergize the features of both hydrogels and conducting polymers and have gained ground in various applications such as energy storage devices, catalysis and sensors. Conventional synthesis of CPHs usually couples with introducing of non-conductive polymer frameworks or chemical oxidative initiators, which will inevitably lead to degraded electrochemical performance and long rinse time. Here, we report an electrochemical polymerization method free of frameworks and initiators to build three-dimensional (3D) polyaniline/phytic acid supramolecular hydrogel. This CPH provides high conductivity of 0.43 S cm(-1) and improved electrode interfaces between electronic transporting phase and ionic transporting phase. As a result, the CPHs exhibit large areal capacitance of 561.6 mF cm(-2) and specific capacitance of 311.3 F g(-1). Flexible solid-state micro-supercapacitors (MSCs) based on this CPHs deliver high areal capacitance of 135.9 mF cm(-2) and considerable integratable potential via tandem and parallel connection. Cyclic stability is demonstrated by 10,000 galvanostatic charge/discharge cycles with 76% capacitance retention. Besides, electrochemical performance of this device can be maintained under different mechanical loadings such as bending and twisting, which makes it a promising power supply candidate for future wearable electronics and on-chip integrated circuit. (C) 2019 Elsevier Ltd. All rights reserved.