Poorly-crystallized poly(vinyl alcohol)/carrageenan matrix: Highly ionic conductive and flame-retardant gel polymer electrolytes for safe and flexible solid-state supercapacitors

Abstract

Gel polymer electrolyte (GPE) based on poly(vinyl alcohol) (PVA) is widely reported due to its excellent mechanical strength, low cost, nontoxicity, and chemical stability. However, the low ionic conductivity that attributed to semi-crystalline structure and the high flammability of PVA limits its application in solid-state supercapacitors (SSCs). Herein, we use self-flame-retardant carrageenans (Car) to form hygrogen bonds with PVA molecular chains and improve their energy of nucleation. The obtained blend PVA/Car GPE displays low crystallinity, high ionic conductivity and excellent flame-retardant performance. The SSCs fabricated by PVA/Car GPE and activated carbon electrodes exhibit a high specific capacitance (406 mF cm−2 at 5 mA cm−2) and an excellent rate performance (99.9% capacitance retention after 5500 cycles). Furthermore, the flexible SSC in the bent state does not show any change and can drive a light-emitting diode successfully. The present work highlights a novel biomass strategy to reduce the crystallinity of PVA and obtain flame-retardant hybrid GPE simultaneously, which provides opportunities for flexible electronics with greatly enhanced ionic conductivity and safety.