Lignin-derived hard carbon (LHC) has emerged as a promising electrode material for supercapacitor applications due to its abundance, sustainability, and excellent electrochemical properties. However, one of the major challenges for free-standing LHC electrodes in practical applications is achieving a balance among high performance, sufficient mechanical strength, and scalable fabrication. In this study, we developed a cost-effective and production-efficient method that combines alkali metal doping with controlled pyrolysis temperature to precisely tailor the porosity and surface chemistry of free-standing LHC. The electrode with optimized surface properties and pore structure delivers high specific capacitance, excellent rate capability, and superior cyclability, even under high areal mass loading. This work highlights the potential of biomass-derived carbons for the scalable production of free-standing, high-performance electrodes for next-generation supercapacitors.
