Facile Synthesis of Polyacrylic Acid/Graphene Oxide Composite Hydrogel Electrolyte for High-Performance Flexible Supercapacitors

The development of hydrogel electrolytes plays a critical role in high-performance flexible supercapacitor devices. Herein, a composite hydrogel electrolyte of polyacrylic acid (PAA) and graphene oxide (GO) has been successfully prepared, where the oxygen-containing functional groups of GO may crosslink and form hydrogen bonds with carboxyl on the molecular chain of PAA, thereby significantly enhancing the mechanical properties of a PAA-based gel electrolyte. The tensile strength increases from 4.0 MPa for pristine PAA gel to 6.1 MPa for PAA/GO composite gel, with the elongation at break rising from 1556% to 1950%. Meanwhile, GO promotes the transportation of electrolyte ions, which are favorable for enhancing the ionic conductivity of the PAA hydrogel. As a result, the assembled supercapacitor based on PAA/GO composite hydrogel electrolyte shows enhanced capacitance retention of 64.3% at a large current density of 20 A g−1 and excellent cycling stability over 10,000 cycles at 5 A g−1. Furthermore, the fabricated flexible supercapacitor devices could maintain outstanding electrochemical performance at various bending angles of 0–90°, indicating a promising prospect for the PAA/GO hydrogel electrolyte in flexible wearable fields.