Crystal modification of iron oxide scale by potassium addition and its application to lithium-ion battery anodes

• Published in: Journal of power sources 2013-11, Vol.242, p.357-364
• Main Authors: Jung, Dong-Won, Han, Sang-Wook, Kong, Byung-Seon, Oh, Eun-Suok
• Format: Article
• Language: English
• Subjects: Anode active materials; Anodes; Applied sciences; Crystals; Cycles; Direct energy conversion and energy accumulation; Discharge; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical characterization; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Iron oxide scale; Iron oxides; Lamellar structure; Lithium-ion batteries; Lithium-ion battery; Materials; Potassium; Potassium iron oxide
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.05.091

This paper proposes a valuable method to reuse the iron oxide scale (IOS) often produced in the steel industry as an anode active material in lithium-ion batteries (LIBs). The IOS samples are prepared via quenching of carbon steel and simple oxidation at a high temperature with or without sequential treatment by potassium hydroxide. Morphological and physical characterizations confirm the formation of a lamellar structure of orthorhombic KFeO2 with a high degree of crystallinity in the potassium-added IOSs. Additionally, the potassium addition decreases the particle size of the crystals and increases the d-spacing between crystal layers. Electrochemical performance tests show that the discharge capacities of the IOS samples monotonically increased with increasing number of charge/discharge cycles regardless of the existence of potassium. In addition, the rate of increase is larger in the potassium-added IOS samples containing the lamellar KFeO2 structure. Consequently, after prolonged cycling (more than 500 cycles), the potassium-added IOS sample retains a discharge capacity of 1020 mAh g−1 with good cycling stability, while the IOS quenched sample only exhibits a capacity of 956 mAh g−1. This result is attributed to the unique structure of the KFeO2 crystals formed in the potassium-added IOS particles. [Display omitted] •We suggest a simple method to reuse iron oxide scale (IOS) as anode materials in LIBs.•The IOSs are successfully modified by KOH via a thermal diffusion process.•KOH-treated IOS exhibits excellent cyclic capability and high reversible capacity.•This improved performance is attributed to the unique structure of KFeO2 crystals.