Ultrathin Hierarchical Porous Carbon Nanosheets for High‐Performance Supercapacitors and Redox Electrolyte Energy Storage

Abstract

The design of advanced high-energy-density supercapacitors requires the design of unique materials that combine hierarchical nanoporous structures with high surface area to facilitate ion transport and excellent electrolyte permeability. Here, shape-controlled 2D nanoporous carbon sheets (NPSs) with graphitic wall structure through the pyrolysis of metal-organic frameworks (MOFs) are developed. As a proof-of-concept application, the obtained NPSs are used as the electrode material for a supercapacitor. The carbon-sheet-based symmetric cell shows an ultrahigh Brunauer-Emmett-Teller (BET)-area-normalized capacitance of 21.4 µF cm (233 F g ), exceeding other carbon-based supercapacitors. The addition of potassium iodide as redox-active species in a sulfuric acid (supporting electrolyte) leads to the ground-breaking enhancement in the energy density up to 90 Wh kg , which is higher than commercial aqueous rechargeable batteries, maintaining its superior power density. Thus, the new material provides a double profits strategy such as battery-level energy and capacitor-level power density.

Synthesis Strategies of Porous Carbon for Supercapacitor Applications

“…The HPCNFs‐N exhibited a high SSA of 417.9 m 2 g −1 and specific capacitances of 307.2 and 193.4 F g −1 at 1 and 50 A g −1 , respectively. PCNSs can be fabricated by pyrolysis of K‐MOF nanorods at temperatures of 200, 450, and 800 °C (Figure 11c) 187. The carbon nanosheets possessed the highest SSA of 1678 m 2 g −1 among various MOF‐derived porous carbons, which may be ascribed to the small‐sized potassium compounds after pyrolysis and the possible activation effect of potassium oxide and carbonates.…”

Three‐Dimensional Graphene‐based N‐doped Carbon Composites as High‐Performance Anode Materials for Sodium‐ion Batteries

“…248 was observed in the NCL@GF and NCF-GF, implying an amorphous carbon phase. [20] The specific surfacea rea of the NCL@GF wasr ecorded up to 277 m 2 g À1 by Brunauer-Emmett-Teller (BET) method, which markedly contrasted thato fG F(% 179 m 2 g À1 )a nd NCF-GF (57 m 2 g À1 )( FigureS2b). In PI and PI@GF samples, the peaks at 1650 and 1334 cm À1 corresponded to the C=O symmetric stretching vibration andC ÀNs tretching vibration, respectively.…”

Design and Fabrication of Printed Paper‐Based Hybrid Micro‐Supercapacitor by using Graphene and Redox‐Active Electrolyte

“…[24] Pech andc o-workers reported ac apacitance of 2.1 mF cm À2 for an inkjet-printed graphene micro-supercapacitor with an Et 4 NBF 4 electrolyte, [25] whereas Bae et al attained around 0.4 mF cm À2 areal capacitance by using graphene and ZnO nanowires. [28,29] The amountso fi odide species adsorbed onto the graphene surfacew ere found to be 86 at %, which slightly decreaseda fter the first charge (to around7 8at%)a nd thereafter remained constant (at around 77 at %). [27] The general goal of hybrid materials design is to combine the properties and identify synergies between two different materials.…”