Lignite-derived porous carbon aerogels for high-performance supercapacitors via a mild H2O2 oxidation strategy

A low-cost, porous carbon aerogel derived from lignite has been successfully developed as an electrode material for supercapacitors designed for high-efficiency energy storage. The assembled device achieves an energy density of 7.92 Wh kg −1 , making it highly competitive. Unlike traditional methods requiring extensive cleaning, this work employs a mild, acid-free H 2 O 2 oxidation strategy to directly convert lignite into soluble precursors without extra impurity removal steps. This green approach significantly simplifies the preparation process and reduces chemical consumption. The selective oxidation introduces abundant oxygen-containing groups (e.g., -COOH, -OH), which facilitate the formation of a robust sol-gel network and induce a hierarchical microporous–mesoporous architecture (average pore size: 3.76 nm) during carbonization. Consequently, the optimized material (CA-700) delivers a specific capacitance of 252.65 F g −1 at 0.5 A g −1 . When assembled into a symmetric supercapacitor, the device exhibits excellent cycling stability, retaining 85.11% of its initial capacitance after 10,000 cycles. This study proposes a low-cost, green, and efficient process for upgrading abundant low-grade coal into high-value-added electrode materials, offering a more economical and environmentally friendly pathway for preparing supercapacitor electrodes.