Kraft lignin-derived free-standing carbon nanofibers mat for high-performance all-solid-state supercapacitor

• Published in: Materials chemistry and physics 2021-05, Vol.264, p.124454, Article 124454
• Main Authors: Singh, Mandeep, Gupta, Ashish, Sundriyal, Shashank, Jain, Karishma, Dhakate, S.R.
• Format: Article
• Language: English
• Subjects: Aqueous electrolytes; Carbon fibers; Carbon nanofiber; Electrochemical analysis; Electrodes; Electrolytes; Energy density; Energy storage; Free-standing; Heat treatment; Kraft lignin; Lignin; Nanofibers; Polymer gels; Solid state; Solid-state supercapacitor; Sulfuric acid; Supercapacitors; Workstations
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.124454

In the present investigation, renewable kraft lignin-based nanofibers were synthesized by facile electrospinning technique and further converted into carbon nanofibers (CNFs) by heat treatment at different temperatures (600, 800 and 1000 °C). These different heat treated carbon nanofiber mats were characterized using SEM, Raman, FTIR, BET and electrochemical workstation. These CNFs were used as a free-standing electrode and characterized for electrochemical performance using a three-electrode system. Among different electrodes, the 800 °C heat treated CNF electrode shows higher specific capacitance (196.63 F/g @ 1 A/g) as compared to the 600 and 1000 °C heat treated CNF electrodes. Based on the electrochemical performance, 800 °C heat treated CNF electrode is selected to assemble two different types of symmetrical supercapacitor devices i.e., aqueous (using 1 M H2SO4) and solid-state electrolyte using PVA-1M H2SO4 polymer gel. The solid-state electrolyte device operating potential window of 0–2 V which is higher than that of an aqueous electrolyte based device. In addition to this, it delivers higher energy and power density as 62.6 Wh/kg and 1.25 kW/kg respectively with an efficiency of 99.5% after 10,000 cycles. These remarkable results of Kraft lignin-derived ribbon type CNF based solid-state symmetrical supercapacitor device opens new paths for the development of futuristic carbon-based free-standing mat as energy storage devices. •Lignin (90%) based carbon nanofibers synthesized by electrospinning and heat treatment at different temperatures.•Effect of heat treatment on microstructure, surface area and functional groups has been studied extensively.•The assembled symmetrical solid state supercapacitor device operates within a wide potential window of 0–2 V.•It shows superior long cycle life of 99.5% after 10,000 charge-discharge cycles.•The solid-state supercapacitor device shows high values of energy (62.6 Wh/kg) and power (1.25 kW/kg) density.