Palm Spathe Derived N-Doped Carbon Nanosheets as a High Performance Electrode for Li-Ion Batteries and Supercapacitors

Recently, biomass derived carbons have gained enormous attention mainly due to their abundance, the environmental, and cost factors associated with utility in energy conversion and storage systems. The search for new, robust, and economically viable carbon sources that can produce efficient porous carbons with desirable textural properties remains a current focus of research. The present study demonstrates a facile scalable method to produce hierarchical nitrogen-implanted carbon nanosheets (NCNS) with a large surface area of 1297 m2 g–1, a pore volume of 0.68 cm3 g–1, and mesopores of diameter 4.2 nm from palm spathe biomass (borassus flabellifer). The 2D carbon nanostructures stem from the implantation of alien nitrogen atoms into the aromatic carbon lattice or grafting of N onto the carbon basal planes or edge sites as evident from X-ray photoelectron spectroscopy. The X-ray diffraction, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy confirmed the 2D nanosheet morphology. The NCNS layered carbon nanostructures have been scrutinized as potential energy storage materials in Li-ion batteries (LIBs) and supercapacitors (SCs). Investigation of NCNS as anode materials in LIBs delivers a high reversible capacity of 477 and 414 mAh·g–1 at 0.1 and 0.2 C rate, respectively, with ∼100% Coulombic efficiency after 100 (dis)charge cycles. Tested as supercapacitors, the NCNS constructed electrode delivers an impressive specific capacitance of 268 and 218 F·g–1 at a applied current of 1 and 5 A·g–1, respectively. The electrode maintains a remarkable capacity retention of ∼99% Coulombic efficiency after 15 000 (dis)charges using 1 M H2SO4 as an aqueous electrolyte. The NCNS constructed electrode achieved a high energy density of 20.83 Wh·kg–1 with the power density of 37 494 W·kg–1. Such exquisite properties of biomass derived NCNS are mainly ascribed to a combined effect of 2D sheet morphology, large specific surface area, hierarchical bimodal pore architecture, and implanted nitrogen atoms.