Facile, Scalable, Eco-Friendly Fabrication of High-Performance Flexible All-Solid-State Supercapacitors

• Main Authors: Jincy Parayangattil Jyothibasu, Rong-Ho Lee
• Format: Article
• Language: English
• Published: MDPI AG 2018-11-01
• Series: Polymers
• Subjects: kapok fiber; polypyrrole; carbon nanotube; freestanding electrode; all-solid-state symmetric supercapacitor
• Online Access: https://www.mdpi.com/2073-4360/10/11/1247

A highly porous freestanding supercapacitor electrode has been fabricated through a simple, inexpensive, bulk-scalable, and environmentally friendly method, without using any extra current collector, binder, or conducting additive. Benefiting from its unique micro-tubular hollow structure with a thin cell wall and large lumen, kapok fiber (KF) was used herein as a low-cost template for the successive growth of polypyrrole (PPy) through in situ chemical polymerization. This PPy-coated KF (KF@PPy) was blended with functionalized carbon nanotubes (<i>f</i>-CNTs) to form freestanding conductive films (KF@PPy/<i>f</i>-CNT) through a simple dispersion and filtration method. The hybrid film featuring the optimal composition exhibited an outstanding areal capacitance of 1289 mF cm^&#8722;2 at a scan rate of 5 mV s^&#8722;1. Moreover, an assembled all-solid-state symmetric supercapacitor featuring a PVA/H₂SO₄ gel electrolyte exhibited not only areal capacitances as high as 258 mF cm^&#8722;2 (at a scan rate of 5 mV s^&#8722;1) but also excellent cycling stability (97.4% of the initial capacitance after 2500 cycles). Therefore, this efficient, low-cost, scalable green synthesis strategy appears to be a facile and sustainable way of fabricating high-performance flexible supercapacitors incorporating a renewable cellulose material.