Laser carbonization of lignin-based fiber membranes with heating treatment for flexible supercapacitors

[Display omitted] •Direct laser writing carbonization and heating treatment are used to manufacture carbon fibers.•Heat treatment can increase the specific surface area of carbonized lignin fiber.•A flexible supercapacitor constructed of carbon fibers has the qualities of being light, thin, and breathable. Electrode materials significantly impact supercapacitor performance and developing high-performance electrode materials is crucial in energy storage. Commonly used laser-induced electrode materials are currently limited by severe contamination and hard-to-change intrinsic properties. This paper proposes a method for fabricating high-performance supercapacitors by laser carbonizing the lignin composite fiber membranes with heating treatment. Lignin fiber can achieve superior tensile strength, stiffness, and carbonization degree under suitable heat treatment temperatures. Heat treatment at 450 °C has been proven to be the ideal temperature for supercapacitor performance. At a current density of 1 A/g, the supercapacitor can reach the highest specific capacitance of ∼391.2F/g. In addition, doping MoS2 boosted the device's performance to a specific capacitance of ∼527.8F/g, a power density of ∼500 W/kg, and an energy density of ∼73 Wh/kg at the same current density. In addition, lignin fibers are ideal materials in electronic textiles due to their soft, thin, and breathable properties. This study provides supportive evidence and technical guidance for improving the performance of flexible wearable supercapacitors.