Electrochemical preparation of nanostructured TiO 2 as anode materials for Li ion batteries
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1127-T01-02
Electrochemical preparation of nanostructured TiO2 as anode materials for Li ion batteries Huanan Duan1, Xiangping Chen1, 2, Joe Gnanaraj3, and Jianyu Liang1 1 Department of Mechanical Engineering, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, U.S.A. 2 College of Material Science & Technology, South China University of Technology, Guangzhou, Guangdong 510644, China. 3 Yardney Technical Products, Inc., 82 Mechanic Street, Pawcatuck, CT 06379, U.S.A. ABSTRACT TiO2 is an attractive anode material for Li-ion batteries due to its high capacity, high mechanical stability during Li intercalation/deintercalation process, limited side reactions with the electrolyte, low cost, and environmental friendliness. In this study, titanium hydroxide gel films were prepared in acidic aqueous solutions of TiOSO4, H2O2 and KNO3 by potentiostatic cathodic electrosynthesis on various copper substrates, including planar Cu foil, mechanically polished planar Cu foil, and Cu nanorod arrays grown on Cu foil. Crystalline TiO2 films were obtained by heat treating the electrodeposited titanium hydroxide gel films at 500 oC in argon atmosphere. The morphology and microstructure of the TiO2 films were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). SEM results showed that after deposition, each Cu nanorod has been covered by a layer of TiO2 gel, forming a core-shell structure. The effects of Cu nanorod arrays on the morphology and the electrochemical property of the TiO2 deposits were discussed. INTRODUCTION Lithium-ion (Li-ion) batteries are attractive candidates for use as power storage in many applications because of their high specific energy, energy density and cycle life. The conventional Li-ion batteries have achieved great commercial success since their invention in 1980’s. However, They have been suffering from two major problems. Firstly, when the charge/discharge rate is higher than 1 C (C defined as the full use of the capacity in 1 h) or Li ions are inserted into graphite at a potential of less than 1 V versus Li+/Li, lithium may be plated on the carbon electrode surface causing safety hazard [1]. Secondly, slow solid-state diffusion of Li+ within the electrode materials limits the rate capability of Li-ion batteries [2,3]. Therefore there is a vigorous research effort on using nanomaterials to improve the safety and the rate capabilities of electrodes. TiO2 is a promising anode material for next-generation Li ion batteries. Various nanoforms of TiO2, including nanocrystalline anatase, amorphous TiO2 and TiO2 nanotubes, have been studied as high-rate Li-ion anode materials and indeed demonstrated improved property at high current densities [4,5,6,7,8,9]. Of the various polymorphs of TiO2, anatase, amorphous or unique nanostructured TiO2 is desirable for fast and high volume lithium insertion/desertion. It has also been shown that not only the particle size of the active materials making up the electrode but also the size of grains within these particles plays cri
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