Lignin based regenerated cellulose guided supramolecular reassembly from waste MDF into nitrogen-doped hierarchical carbons for sustainable energy storage.

The efficient and sustainable conversion of lignocellulosic biomass into carbon materials remains a significant challenge due to weak interfacial interactions and poor pore structure control. Herein, a supramolecular deconstruction-reconstruction strategy coupled with defect engineering is reported for the upcycling of waste medium-density fiberboard into nitrogen-doped biochar for supercapacitor electrodes, thereby mitigating landfill waste and reducing environmental impact. Acidic lithium bromide selectively disrupts cellulose fibers, followed by ethanol-induced regeneration into a sub-nanoporous template. This template binds lignin via π-π stacking, constructing a mesoporous network with large specific surface area. Melamine-urea-formaldehyde resin acts as an in-situ nitrogen source, achieving uniform doping to enhance capacitive storage. The biochar achieves a specific capacitance of 333.8F/g in 6 M KOH, while the symmetric supercapacitor exhibits 17.7 Wh/kg energy density and 95.3 % capacitance retention over 10,000 cycles. This work integrates component synergy, hierarchical structure and surface chemistry, providing a scalable pathway for biomass-derived energy storage materials.