*Article* **Active Carbon-Based Electrode Materials from Petroleum Waste for Supercapacitors**

**Abdualilah Albaiz, Muhammad Alsaidan, Abdullah Alzahrani, Hassan Almoalim, Ali Rinaldi \*,† and Almaz S. Jalilov \***

> Department of Chemistry and Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia

**\*** Correspondence: ali.rinaldi@tum.de (A.R.); jalilov@kfupm.edu.sa (A.S.J.)

† Current Address: Faculty of Chemistry, School of Natural Sciences, Technical University of Munich, Lichtenbergstrasse 4, 85748 Garching bei München, Germany.

**Abstract:** A supercapacitor is an energy-storage device able to store and release energy at fast rates with an extended cycle life; thus, it is used in various electrical appliances. Carbon materials prepared above 800 ◦C of activation temperatures are generally employed as an electrode material for supercapacitors. Herein, we report carbon materials prepared from a low-cost petroleum waste carbon precursor that was activated using KOH, MgO, and Ca(OH)<sup>2</sup> only at 400 ◦C. Electrode materials using low-temperature activated carbons were prepared with commercial ink as a binder. The cyclic voltammetry and galvanostatic charge–discharge were employed for the electrochemical performance of the electrodes, and studied in a 3-electrode system in 1 M solutions of potassium nitrate (KNO<sup>3</sup> ) as electrolyte; in addition, the supercapacitive performance was identified in a potential window range of 0.0–1.0 V. The best-performance activated carbon derived from vacuum residue with a specific surface area of 1250.6 m2/g exhibited a specific capacitance of 91.91 F/g.

**Keywords:** activated carbon; vacuum residue; supercapacitor; carbon nanotechnology
