Template Synthesis of 2D Carbon Nanosheets: Improving Energy Density of Supercapacitors by Dual Redox Additives Anthraquinone-2-sulfonic Acid Sodium and KI

Abstract

How to massively produce 2D carbon materials remains an interesting issue. In this work, by a template carbonization approach, 2D carbon nanosheets possessing large surface area of 1229 m2 g–1 and high pore volume of 1.66 cm3 g–1 have been synthesized, using sodium stearate as the carbon source and magnesium powder as a hard template. More importantly, dual redox additives KI and anthraquinone-2-sulfonic acid sodium (AQS) are developed for remarkably improving the capacitances; neutral KNO3 electrolyte can synchronously extend the operating voltage window. It is revealed that KI and AQS undergo redox reactions at the positive and negative electrodes, respectively; the operating voltage window can be prolonged up to 1.8 V, larger than the limitation of water (1.23 V). Introducing dual redox additives KI and AQS into KNO3 electrolyte results in a high energy density of 33.81 Wh kg–1. The present strategy that utilizes dual redox additives occurring at the positive and negative electrodes respectively has pr...