Low cost, high performance flexible asymmetric supercapacitor based on modified filter paper and an ultra-fast packaging technique

Abstract

A flexible all-solid-state asymmetric supercapacitor (FAAS) was prepared via a low-cost method with commonly used paper fibers as the substrate and a modified polymer-based hydrogel as the electrolyte. In the designed structure of the positive electrode, a three dimensional network of stacked thin film based on paper fibers (PFs), chemically reduced graphene oxide (RGO) and the electro-polymerization of polyaniline (PANI) nanorods was prepared via an extended filtration assisted method. The fabricated PF–RGO–PANI electrodes exhibit large specific capacitance of 587 F g⁻¹ at the current density of 0.8 A g⁻¹ and excellent cycling stability (99.6% retention of initials specific capacitance even after 5000 cycles). PF–RGO film was introduced as the negative electrode for the designed asymmetric supercapacitor. During the preparation process of FAAS, a glutaraldehyde (GA) cross-linked PVA–H₂SO₄ hydrogel was not only used as the electrolyte but also explored as a separator and external packaging material prepared by a fast layer-by-layer assembly technique within one minute. The resulted FAAS exhibits a maximum energy density and power density of 175 W h kg⁻¹ and 9200 W kg⁻¹. Moreover, superior mechanical stability of the FAAS has been demonstrated by testing its bending and folding performance, which retains over 84% of its original specific capacitance even after 2000 cycles of bending and folding. The simple and low-cost preparation process of electrodes, the ultra-fast flexible supercapacitor assembling and the efficient packaging technique proposed in this study provide a good contribution to the development of FAAS for the next generation flexible energy storage devices.