From Phenolated Lignin to Few-Layered Graphene: Laser-Induced Carbonization for Micro-Supercapacitor Application

This study explores the potential of phenolated lignin as a precursor for synthesizing graphene-like carbon materials through laser-induced carbonization (LIC). Key parameters─including formulation, laser speed, laser power, and lignin loading─were optimized to enhance the quality of the resulting LIC materials. Under optimized conditions, this method produced a high-quality, few-layer graphene-like carbon material. Comprehensive materials characterization (XPS, XRD, TGA, Raman spectroscopy, sheet resistivity, and elemental analysis) revealed that the material’s conductivity is driven by the formation of an sp2-hybridized conjugated carbon system and the reduction of both sp3-hybridized carbon and oxygen groups. The introduction of phenolic groups into the lignin structure enhanced its thermostability and conversion efficiency to graphene-like carbon, achieving a low sheet resistance of 6.7 Ω·sq–1. This study demonstrates that phenolated lignin is a promising precursor for the synthesis of conductive graphene-like carbon materials with excellent electronic properties, making it suitable for micro-supercapacitor applications. Furthermore, the resulting printed device exhibited a specific capacitance of 454 mF cm–3 (1.4 mF cm–2) at a scan rate of 5 mV s–1 in cyclic voltammetry (CV) mode and 286 mF cm–3 (0.86 mF cm–2) at a current density of 0.05 mA cm–2 in galvanostatic charge–discharge (GCD) mode.