Sulfur and nitrogen codoped cyanoethyl cellulose?derived carbon with superior gravimetric and volumetric capacity for potassium ion storage

We fabricated sulfur and nitrogen codoped cyanoethyl cellulose-derived carbons (SNCCs) with state-of-the-art electrochemical performance for potassium ion battery (PIB) capacitor (PIC) anodes. At 0.2, 0.5, 1, 2, 5, 10 A g?1, the SNCC shows reversible capacities of 369, 328, 249, 208, 150, 121 mA h respectively. Due to a high packing density 1.01 g cm?3, volumetric are also uniquely favorable, being 373, 331, 251, 210, 151, 122 cm?3 at these currents, promising initial Coulombic efficiency 69.0% extended cycling stability 99.8% capacity retention after 1000 cycles. As proof principle, an SNCC-based PIC is tested, achieving 94.3 Wh kg?1 237.5 W sustaining over 6000 cycles 30 g?1 84.5% retention. The internal structure S N based on highly dilated defective graphene sheets arranged into nanometer-scale walls. Using baseline S-free carbon comparison (termed NCC), role doping resultant was elucidated. According galvanostatic intermittent titration technique impedance spectroscopy analyses, as well COMSOL simulations, this promotes rapid solid-state diffusion ions solid electrolyte interphase that stable during cycling. X-ray diffraction used probe storage mechanisms in SNCC, establishing intercalation presence KC36, KC24, KC8 phases low voltages.