Mill scale-derived hematite as a low-cost supercapacitor electrode material
9th International Symposium on Materials for Energy Storage & Conversion (MESC-IS-2025), Kocaeli, Türkiye, 1 - 04 Eylül 2025, ss.42, (Özet Bildiri)
- Yayın Türü: Bildiri / Özet Bildiri
- Basıldığı Şehir: Kocaeli
- Basıldığı Ülke: Türkiye
- Sayfa Sayıları: ss.42
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
Energy has become an increasingly critical need in modern societies. Sectors such as industry, transportation, agriculture, and healthcare rely on a continuous power supply, making energy production and management a strategic priority. In this context, the efficient storage and reuse of energy through highperformance storage systems have gained great importance [1]. Due to the limitations of conventional storage systems like lithium-ion and lead-acid batteries, supercapacitors have attracted growing interest as next-generation electrochemical energy storage devices. Their key advantages include long cycle life (>1000 cycles), lightweight structure, fast chargedischarge capability, and reliable operation over a wide temperature range [2]. Transition metal oxides are commonly used as electrode materials in supercapacitors because their multiple oxidation states enable redox reactions that enhance specific capacitance and energy density [3]. However, their high production cost limits commercial use. Utilizing recycled waste-derived materials as electrodes offers a cost-effective and environmentally sustainable alternative [4,5]. Mill scale is a brittle layer of iron oxide formed on steel surfaces during high-temperature processes such as hot rolling or heat treatment. It mainly consists of FeO, Fe₃O₄, and Fe₂O₃, depending on the processing conditions [6]. Although often treated as waste, its high iron oxide content makes it a promising low-cost electrode material for energy storage applications. In the present study, mill scale was subjected to chemical treatment using sulfuric acid (H₂SO₄) solutions to leach iron ions. The pH of the resulting solution was carefully adjusted to facilitate the precipitation of iron hydroxide. Subsequently, a thermal treatment was applied to convert the precipitate into hematite (Fe₂O₃). The structural and morphological properties of the synthesized Fe₂O₃ were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, which provided insights into its crystallographic phases and surface morphology, respectively. The obtained Fe₂O₃ was then utilized as an active electrode material in the fabrication of asymmetric coin-cell supercapacitors. The electrochemical performance of the assembled supercapacitors was systematically evaluated through a series of electrochemical techniques, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) measurements. These analyses were employed to assess key performance metrics such as specific capacitance, charge-discharge capability, and the cycling stability of the Fe₂O₃-based supercapacitors.