Multistage Activation of Anthracite Coal-Based Activated Carbon for High-Performance Supercapacitor Applications

Abstract

An anthracitic coal-derived activated porous carbon is proposed as a promising carbon electrode material for supercapacitor (SC) applications. The specific capacitance of this activated carbon SC electrode is related to the characteristics, such as specific surface area, pore size distribution, wettability, and conductivity. In the present work, a series of anthracite-based activated carbons (ABAC) were prepared via a multistage activation process and used as electrode materials for SCs. The multistage activation experiment was developed by exploring different activation temperatures, precursor/activating agent mass ratios, and process treating environments. The electrochemical performance of ABACs was evaluated in a three-electrode testing system. Multiple electrolytes were utilized, such as 1 M sulfuric acid (H2SO4) and 1 and 6 M potassium hydroxide (KOH) solutions. An optimum ABAC electrode was obtained, characterized by its largest wettability and superior conductivity, and achieved excellent electrochemical performance. The three-electrode system exhibited a specific capacitance of 288.52 and 260.30 F/g at 0.5 A/g in the 1 M H2SO4 and 6 M KOH electrolytes, respectively. It was found that moderate multistage activation temperatures are beneficial for the electrolyte uptake which enhances the specific capacitance. The high content of the oxygen functional groups on the activated carbon surface greatly improved its specific capacitance due to the increase in wettability. In the 1 M H2SO4 electrolyte, the working electrode exhibited better performance than in 1 M KOH because the ion diameter in the acidic electrolyte was more suitable for pore diffusion. The concentrated KOH electrolyte leads to an increase in specific capacitance due to increased ions being adsorbed by a certain number of the hydrophilic pores. Moreover, the specific capacitance of the optimum ABAC sample remained at 95.4% of the initial value after 1000 galvanostatic charge–discharge tests at 0.5 A/g, which is superior to the performance of SC grade commercial carbon.

One-Pot Ultrafast Molten-Salt Synthesis of Anthracite-Based Porous Carbon for High-Performance Capacitive Energy Storage

“…This is attributed to the highly active intercalation and pore-forming behavior of the KCl/K 2 CO 3 binary salts to anthracite at 900 °C, leading to an optimal number of active sites being produced in TPC. This value also exceeds many previously reported C g values of anthracite-based carbon materials − ,,− (Table S4) and carbon materials prepared by the conventional molten-salt method in tube furnaces ,,,− (Table S5). The thickness of the electrode is shown in Figure S8c, according to the formula for calculating the volume capacitance, the HPC and TPC electrodes exhibit volume capacitances of 231.2 F cm –3 and 142.6 F cm –3 , respectively.…”

“…8,9 As an inexpensive and widely distributed mineral, anthracite features high carbon content over 90% with abundant carbon skeletons, 10 holding unique advantages as a carbon source for preparing porous carbon material. 11 Transforming anthracite into novel energy storage materials facilitates the high addedvalue utilization of coal resources, thereby stimulating broad research interest. 12,13 Generally, the synthesis of anthracitebased porous carbon involves the use of strong oxidants 14 or activating agents, 15 making the reaction process corrosive and/ or hazardous.…”

Enhancing Supercapacitive Swing Adsorption of CO2 with Advanced Activated Carbon Electrodes

“…The results indicate that high surface area activated carbons with high specific capacitances investigated for supercapacitor research can be directly used for SSA. [51][52][53] Table S8 (Supporting Information) shows a comparison of capacitances of some recently reported biomass-derived porous carbon electrodes.…”

Review on Coal-Based Activated Carbon: Preparation, Modification, Application, Regeneration, and Perspectives

“…Song et al 120 prepared an electrode material for supercapacitors with anthracite as the raw material. The threeelectrode system exhibited specific capacitances of 288.52 and 260.30 F/g at 0.5 A/g in 1 M H 2 SO 4 and 6 M KOH electrolytes, respectively.…”