A Coconut Leaf Sheath Derived Graphitized N‐Doped Carbon Network for High‐Performance Supercapacitors

Abstract

A highly graphitized nitrogen‐doped carbon network is synthesized from biomass, obtained from coconut tree leaf sheath and successfully demonstrates high energy storage properties for use in supercapacitors. A simple thermal physical activation in carbon dioxide atmosphere also enables the electrochemical activity of the carbon to be improved. A detailed study is carried out to understand the dependence of the electrochemical performance on parameters such as the concentration of urea used for doping, the activation temperature, and time of activation. An optimized sample is obtained to give a very high electrochemical performance. Our best sample, obtained by using a 0.5 M urea solution for doping, annealed at 700 °C under a N2 atmosphere and activated at an activation temperature of 800 °C under a CO2 atmosphere, named 0.5 M‐700 N‐800C, gave a very high specific capacitance of 360.9 F g−1 in 2 M KOH in the potential window of 0 to −1.1 V. This performance as a negative electrode exceeds the specific capacitance of graphene hydrogels (305 F g−1) that we prepared and is more than that of commercially available activated carbon 218.18 F g−1. Thus, it brings to light the possibility of using our material as an efficient, cheap substitute for negative electrode materials like graphene, carbon nanotubes, and activated carbon. This process is facile, extremely cheap, and environmental friendly, which utilizes urea, a non‐hazardous nitrogen dopant.

N‐Doped Hierarchical Porous Carbon with Open‐Ended Structure for High‐Performance Supercapacitors

“…In order to study the rate capability of electrodes, the capacitance retention was calculated at various current densities from GCD curves (Figure e). In detail, the capacitance based on the symmetric A‐HCS electrode decreased from 235 to 171 F/g as the current density increased from 0.2 to 30 A/g, showing a capacitance retention as much as 73 %, which is also higher than the commerical activated carbon ,. In contrast, the capacitance retention is only 46 % for A‐NP.…”

“…EDLCs have been widely utilized in portable electronic devices due to their distinctive electrical properties. In general, EDLCs prefer to employ carbon materials with high surface area, porosity and high electrical conductivity as electrode materials, such as activated carbons,, carbon aerogel, carbon nanosheets,, carbon nanotubes, carbon spheres,, hollow carbon spheres, carbon network, and carbon nanofibers …”

Incorporating Gadolinium Oxide (Gd2O3) as a Rare Earth Metal Oxide in Carbon Nanofiber Skeleton for Supercapacitor Application

“…Additionally, the stability of the electrode materials must ensure a long cycle life and reliable operation. Three main categories of electrode materials are commonly employed: carbon materials, [5][6][7][8] polymers, [9,10] and metal oxides. [11][12][13][14] All three of these materials offer a significant surface area with accessible pore size to facilitate the movement of electrolyte ions.…”

Preparation of Nitrogen and Sulfur Co‐doped and Interconnected Hierarchical Porous Biochar by Pyrolysis of Mantis Shrimp in CO2 Atmosphere for Symmetric Supercapacitors

“…controlled the SSA and pore distribution of nitrogen‐doped carbon aerogels by changing the CO 2 activation time to make the maximum SSA 1415.0 m 2 g −1 with a corresponding specific capacitance of 178.9 F g −1 at 1 A g −1 . Based on the two‐step method, Jin et al [21] . used CO 2 to open pores, widen and generate new pores on the pre‐carbonized spores to form a porous structure with a high SSA.…”