A Highly Durable, Flexible and Asymmetric Supercapacitor with “All‐Organic” Polymeric Electrodes Employing Al‐Ion Electrochemistry

Conducting organic polymers are key components of flexible supercapacitors that power wearable devices and smart electronics. This work presents a flexible supercapacitor using Schiff base polymers (SBP) positive and poly-anthraquinone sulfides (PAQS) negative electrodes in aqueous Al₂(SO₄)₃ electrolyte. The doping/dedoping of Al³⁺ ions in the polymeric structure enables pseudoFaradaic charge storage. SBP and PAQS show respective specific capacitances of 1375 and 1166 mF g^-1 at 50 mA g^-1, with >95% capacitance retention after 3000 cycles at 70 mA g^-1. The 1.2 V flexible asymmetric pouch cell, utilizing low-cost stainless steel (SS304) current-collectors and electrolyte-soaked filter paper separators, exhibits a specific capacitance of 750 mF g^-1 at 50 mA g^-1 and retains 97% capacitance after 3000 cycles at 70 mA g^-1. The supercapacitor demonstrates excellent power performance with a response time of 70 μs, achieving an energy density of 150 mWh kg^-1 at 30 W kg^-1 and a power density of 60 W kg^-1 at 83 mWh kg^-1. Its electrochemical performance remains stable across flat, bent, and rolled states, highlighting its flexibility and mechanical stability. Beyond performance, the scalability, low cost, and environmental impact of the polymeric electrodes make this technology promising for next-generation flexible energy storage.