Nano-sized Fe 3 O 4 /carbon as anode material for lithium ion battery Jie Wang a , Hailei Zhao a, b, * , Zhipeng Zeng a , Pengpeng Lv a , Zhaolin Li a , Tianhou Zhang a , Tianrang Yang a a School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China b Beijing Key Lab of New Energy Materials and Technologies, Beijing 100083, China highlights Nano-sized Fe 3 O 4 /C was prepared by a simple citric-nitrate combustion process. Fe 3 O 4 /C particles show coreeshell structure. Fe 3 O 4 /C powder displays high specic capacity and good cycling stability. Fe 3 O 4 /C composite exhibits a superior rate-capability. article info Article history: Received 28 January 2014 Received in revised form 29 May 2014 Accepted 19 August 2014 Available online 4 September 2014 Keywords: Composite materials Chemical synthesis Electron microscopy Electrochemical properties abstract Nano-sized Fe 3 O 4 /carbon material is prepared via a simple citric-nitrate combustion method combining with a hydrothermal carbon coating technique. The synthesized Fe 3 O 4 /carbon composite shows a high reversible specic capacity (ca. 850 mAh g 1 at 100 mA g 1 ; ca. 600 mAh g 1 at 500 mA g 1 ), good rate- capability as well as superior cycling stability as anode for lithium-ion batteries. The ameliorated elec- trochemical performance of Fe 3 O 4 /carbon electrode is associated to the nano-sized particle feature and the continuous carbon coating layer. The former provides short lithium-ion/electron diffusion distance, while the latter enables the fast electron transport pathways. Besides, the carbon layer can act as a protective component to prevent the active particle Fe 3 O 4 from aggregation and pulverization during the charge/discharge processes. © 2014 Elsevier B.V. All rights reserved. 1. Introduction In view of the ever-increasing environmental problems, including global warming, ecological concerns and the gradual depletion of oil resources, it is of signicance to develop clean and sustainable energy resources. The wind, solar and tidal energies are the representatives of clean energy resources. Their variation in time and dispersiveness in space necessitate the development of high performance energy storage technologies. Lithium ion batte- ries have been considered as the most attractive large scale storage sources owing to the outstanding advantages of no memory effect, longer lifespan, superior energy density, higher operating voltage, low maintenance and the environmental benignity. Lithium ion battery has been widely used in cellular phone, laptop computer, digital camera, and other electronic devices, and is being consid- ered for applications in electric and hybrid electric vehicles [1e6]. However, the graphite material using as the anode can not satisfy the demands for high energy density batteries because of its limited specic capacity (~372 mAh g 1 ). Besides, its inherent character- istics of the lower lithiation potential (below 0.2 V vs. Li þ /Li) and the co-intercalation of solvated lithium ion readily cause safety and capacity degradation problems [7e9]. Thereby, developing advanced anode materials with higher specic capacity to replace the current graphite-based anodes has become extremely urgent. Currently, many types of materials have been considered as the potential high capacity anode materials for lithium-ion batteries, such as Sn-based [7,10e12] and Si-based [13e15] alloys, and tran- sition metal oxides [16e25] (e.g. Fe 2 O 3 /Fe 3 O 4 , Co 3 O 4 , MoO 2 /MoO 3 , MnO 2 , CuO, etc.). Among them, the transition metal oxides are of the interest as the promising anode materials due to the superior theoretical specic capacity (ca. 500e1000 mAh g 1 ) [26] and the high operating potential that can effectively avoid the lithium dendrite formation and attendant safety problem. Different from the classical lithium insertion/extraction or lithium alloying/de- * Corresponding author. School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083, China. Tel./fax: þ86 10 82376837. E-mail addresses: hlzhao@ustb.edu.cn, hlzhao66@gmail.com (H. Zhao). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys http://dx.doi.org/10.1016/j.matchemphys.2014.08.037 0254-0584/© 2014 Elsevier B.V. All rights reserved. Materials Chemistry and Physics 148 (2014) 699e704