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

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.