Scalable,\nQuasi-Solid-State Bio-polymer Hydrogel Electrolytes\nfor High-Performance Supercapacitor Applications

Abstract

The development of eco-friendly, quasi-solid-state bio-polymer\nhydrogel electrolytes has become one of the challenging issues in\nenergy storage. The assembly of safer devices has still been the key\nto be addressed for safety reasons. The present work reports the synthesis\nof bio-polymer electrolytes using sodium carboxy methyl cellulose\n(C)/citric acid (CA) support, which was further intercalated by Hibiscus sabdariffa (H), at various fractions. Stable\nand scalable blends were produced, and the ion transport was effectively\nenhanced via insertion of H, which occurred through Na⁺ and H₃O⁺ ions from the corresponding “host\nand guest”, where no external salt as ion source was inserted.\nThe results showed that H in the hydrogel improved the ionic conductivity\nwhile maintaining the homogeneity and electrochemical stability. CCAH\nwas coated on the carbon composite electrodes, and the devices were\nassembled, followed by experimental analysis under ambient conditions.\nThe device exhibited excellent charge/discharge performance over 10,000\ncycles with a specific capacitance of 442 F g^–1.\nIn addition, the device offers a superior energy density of 72 W h\nkg^–1 at a power density of 331 W kg^–1. Using non-toxic quasi-solid-state bio-polymer electrolyte hydrogels\nin devices may pave the way for safe usage in emerging wearable electronics\nand energy storage systems.