Advanced High‐Energy All‐Solid‐State Hybrid Supercapacitor with Nickel‐Cobalt‐Layered Double Hydroxide Nanoflowers Supported on Jute Stick‐Derived Activated Carbon Nanosheets

Abstract Developing efficient, lightweight, and durable all‐solid‐state supercapacitors is crucial for future energy storage systems. The study focuses on optimizing electrode materials to achieve high capacitance and stability. This study introduces a novel two‐step pyrolysis process to synthesize activated carbon nanosheets from jute sticks (JAC), resulting in an optimized JAC‐2 material with a high yield (≈24%) and specific surface area (≈2600 m 2 g −1 ). Furthermore, an innovative in situ synthesis approach is employed to synthesize hybrid nanocomposites (NiCoLDH‐1@JAC‐2) by integrating JAC nanosheets with nickel‐cobalt‐layered double hydroxide nanoflowers (NiCoLDH). These nanocomposites serve as positive electrode materials and JAC‐2 as the negative electrode material in all‐solid‐state asymmetric hybrid supercapacitors (HSCs), exhibiting remarkable performance metrics. The HSCs achieve a specific capacitance of 750 F g −1 , a specific capacity of 209 mAh g −1 (at 0.5 A g −1 ), and an energy density of 100 Wh kg −1 (at 250 W kg −1 ) using PVA/KOH solid electrolyte, while maintaining outstanding cyclic stability. Importantly, a density functional theory framework is utilized to validate the experimental findings, underscoring the potential of this novel approach for enhancing HSC performance and enabling the large‐scale production of transition metal‐based layered double hydroxides.