Fabrication of hierarchical porous biomass-based carbon aerogels from liquefied wood for supercapacitor applications

Hierarchical porous carbon aerogels were synthesized from liquefied wood via physical and chemical activation processes. The morphology and structure of the KOH-treated carbon aerogel (K-LWCA) and the steam-treated carbon aerogel (H-LWCA) were systematically investigated via scanning electron microscopy, N₂ adsorption–desorption tests, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Additionally, the electrochemical properties of K-LWCA and H-LWCA were evaluated via cyclic voltammetry, galvanostatic charge–discharge processes, and electrochemical impedance spectroscopy. Both H-LWCA and K-LWCA exhibited high specific surface areas (1996 and 1780 cm² g⁻¹, respectively) and well-developed hierarchical porous structures. Compared with H-LWCA, K-LWCA demonstrated higher specific capacitance, improved performance, and superior cyclic stability owing to its higher concentration of defects and hydrophilic functional groups. Moreover, K-LWCA exhibited an optimal mass-specific capacitance of 201.47 F g⁻¹ at 0.5 A g⁻¹, achieved an ideal capacitance retention of 70.15% at 20 A⁻¹, and maintained excellent cycling stability with a retention rate of 94.11% after 5000 cycles. Furthermore, the button symmetric supercapacitor device assembled using K-LWCA demonstrated a specific capacitance of 117.78 F g⁻¹ at 0.5 A g⁻¹ and exhibited an energy density of 9.2 Wh kg⁻¹ at a power density of 375 W kg⁻¹. Therefore, this study provides a novel method for preparing biomass-derived carbon aerogel electrode materials suitable for practical supercapacitor applications.