Highly Efficient KOH Activation Method for the Formation of Enzymatic Hydrolysis Residual Lignin-Based Porous Carbon Materials

Abstract

 Using lignin residue after enzymatic hydrolysis as raw material, resultant lignin-based porous carbon materials were constructed by optimizing the KOH activation process. A single-step activation approach was utilized to investigate how various parameters—including the carbon-to-alkali ratio, activation temperature, and activation duration—influence the physiochemical performance of lignin-derived porous carbon materials. The specific characteristics of the as-synthesized products were tested. Symmetric supercapacitor devices were constructed with KOH serving as the electrolyte medium to assess the material's cycling durability under prolonged galvanostatic charge-discharge conditions. It can be concluded from the experimental findings that the porous carbon specimen designated as ELC700-2-4, which exhibits a large SSA of 3067 m²/g and a microscale pore percentage of 62.18%, can be successfully synthesized under the conditions of an activation temperature of 700 °C, a carbon‑to‑alkali mass rate of 4-to-1, and an carbonization duration of 2 hours. Performance evaluation using a three-electrode configuration reveals that the material exhibits remarkable electro and chemical performance within KOH, delivering a specific capacitance at a current density of 1 A/g with value of 443 F/g. Meanwhile, the ELC700-2-4 electrode achieves a specific capacitance of 250 F/g at 1 A/g and maintains 95.55% of its original capacitance after 10,000 consecutive cycles, reflecting superior cycling stability under repeated charging and discharging processes. At a power density of 500.16 W/kg, the symmetric capacitor shows a high energy density of 8.6 W·h/kg.