Nanocrystalline Cellulose Confined in Amorphous Carbon Fibers as Capacitor Material for Efficient Energy Storage
Doha M. Sayed, Mohamed S. El‐Deab, Mohamed E. Elshakre, Nageh K. Allam
Abstract
The development of sustainable and renewable energy storage systems is a promising approach toward steady and reliable energy supply. In this study, cellulosic palm loofah fibers were used as a precursor to produce amorphous carbon (Am-C) with retained crystalline cellulosic planes via a simple activation method. The Am-C exhibits a fairly high BET surface area of 2000 m2/g and a 3D-microporous structure with small mesopores. The symmetric Am-C//Am-C supercapacitor device tested in 1.0 M NaCl aqueous electrolyte showed specific capacitances of 201 F/g at 5 mV/s and 337 F/g at 1 A/g. The device exhibits a stable performance across a potential window of 1.8 V with ultrahigh energy and power densities of 51.4 Wh/kg at 4.5 kW/kg and 16.95 Wh/kg at 18 kW/kg. The device showed extraordinary increasing capacitive behavior upon cycling at 10 A/g for over 25000 cycles. The exceptional device performance could be ascribed to the electrochemical graphitization during long-term cycling together with the enhanced wettability as confirmed via Raman, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and contact angle measurements.