Dual Molecules Cooperatively Confined In‐Between Edge‐oxygen‐rich Graphene Sheets as Ultrahigh Rate and Stable Electrodes for Supercapacitors

Abstract

Noncovalent modification of carbon materials with redox‐active organic molecules has been considered as an effective strategy to improve the electrochemical performance of supercapacitors. However, their low loading mass, slow electron transfer rate, and easy dissolution into the electrolyte greatly limit further practical applications. Herein, this work reports dual molecules (1,5‐dihydroxyanthraquinone (DHAQ) and 2,6‐diamino anthraquinone (DAQ)) cooperatively confined in‐between edge‐oxygen‐rich graphene sheets as high‐performance electrodes for supercapacitors. Cooperative electrostatic‐interaction on the edge‐oxygen sites and π–π interaction in‐between graphene sheets lead to the increased loading mass and structural stability of dual molecules. Moreover, the electron tunneling paths constructed between edge‐oxygen groups and dual molecules can effectively boost the electron transfer rate and redox reaction kinetics, especially at ultrahigh current densities. As a result, the as‐obtained electrode exhibits a high capacitance of 507 F g−1 at 0.5 A g−1, and an unprecedented rate capability (203 F g−1 at 200 A g−1). Moreover, the assembled symmetrical supercapacitor achieves a high energy density of 17.1 Wh kg−1 and an ultrahigh power density of 140 kW kg−1, as well as remarkable stability with a retention of 86% after 50 000 cycles. This work may open a new avenue for the efficient utilization of organic materials in energy storage and conversion.

Regulating B-Site Metals in Delafossite to Reach Efficient and Selective Peroxymonosulfate Activation for Water Remediation

“…In electrochemical impedance spectroscopy (EIS), when the semicircle’s radius in the high-frequency region is smaller and the straight line in the low-frequency region is more vertical, it signifies a reduction in the electrochemical mass transfer impedance of the catalyst, rendering electron transfer within the catalyst more efficient . As depicted in Figure a, among the four catalysts (CuFeO 2 , CuMnO 2 , CuCoO 2 , and CuCrO 2 ), CuCrO 2 displayed the smallest semicircle radius in the high-frequency region and the straightest line in the low-frequency region followed by CuCoO 2 , CuMnO 2 , and CuFeO 2 .…”

Electrode Materials, Structural Design, and Storage Mechanisms in Hybrid Supercapacitors

“…However, the practical performance of graphene is far below the ideal one due to various reasons. One of the main reasons is that the 2D layered graphene sheets can easily restack to form dense lamellar microstructures, which greatly decreases the specific surface area of the original graphene sheets, causes inferior ion transport capabilities, and renders a substantial number of active sites inaccessible to reactants [ 245 , 246 , 247 , 248 ]. Therefore, a number of strategies have been developed to prevent aggregation of graphene sheets so as to increase surface area and promote the transport of electrolyte ions, including fabricating 3D porous nanostructures [ 249 , 250 ], nitrogen doping [ 251 , 252 , 253 ], and surface modification using molecular modifiers [ 254 , 255 ].…”