Curcumin-Assisted Synergistic Design of Hierarchical Cubic MnO ₂ –Polypyrrole Composite for High-Performance Asymmetric Energy Storage

A sustainable, template-assisted approach is introduced for constructing a hierarchically porous electrode with outstanding electrochemical performance. Curcumin, serving as a sustainable soft template, steers polymerization to form a robust hierarchical nest-like architecture enriched with electroactive sites and continuous charge-transport channels. The intimate integration of MnO 2 within the curcumin-templated polypyrrole matrix (PPY), which enhances structural integrity, accelerates ion diffusion, and amplifies pseudocapacitive activity of MCPPY nanocomposites. For benchmarking, nontemplated MPPY composites, pristine MnO 2, and PPY electrodes were synthesized under identical conditions and systematically assessed. The MCPPY electrode delivers an outstanding specific capacitance of 1028 F g –1 at 1 A g –1, with an electroactive surface area of 1.2 × 10 –3 cm 2, achieving 50.2% utilization of its theoretical capacitance (2.47 × 10 3 F g –1 ) and a high areal capacitance of 19.5 F cm –2 . An asymmetric supercapacitor assembled using MCPPY exhibits a high energy density of 58.8 Wh kg –1 and power density of 2594 W kg –1 while maintaining 96.2% capacitance retention and 100% Coulombic efficiency over 12000 cycles. The device further demonstrates practical viability by powering a red LED for 10 min. This green templating approach offers an effective and scalable pathway toward high-performance, durable, and sustainable energy-storage materials.