Ion beam analysis of partial lithium extraction of LiMn 2 O 4 by chemical delithiation E. Andrade a,⇑ , A. Romero Núñez b , A. Ibarra Palos b , J. Cruz a , M.F. Rocha c , C. Solis a , O.G. de Lucio a , E.P. Zavala a a Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 México, D.F., Mexico b Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, México D.F. 04510, Mexico c ESIME-Z, Instituto Politécnico Nacional, U.P. ALM, G.A. Madero, México D.F. 07738, Mexico article info Article history: Received 8 October 2010 Received in revised form 9 December 2010 Available online 21 December 2010 Keywords: LiMn 2 O 4 Chemical delithiation XRD EBS NRA abstract Lithium manganese oxide, LiMn 2 O 4 , has been studied by many research groups. This material is a great candidate to be used as positive electrode in rechargeable lithium-ion batteries because of its low cost, abundant precursors and non-toxicity. LiMn 2 O 4 has a spinel Fd-3m structure and shows a reversible extraction and insertion of lithium ions that is one of the most important characteristic of positive elec- trodes in rechargeable batteries. In this work, LiMn 2 O 4 samples were synthesized by solid state reaction. A partial lithium removal was performed on this system by chemical delithiation using HCl aqueous solutions at different concentra- tions. Six partial-extracted compounds were obtained and characterized by Ion beam analysis (IBA) in order to obtain the Li concentrations. X-ray diffraction (XRD) and Rietveld analyses were also performed. A rigorous study of lithium contents is critical to analyze the structure properties of these compounds and samples production parameters. The IBA method used in this work was the analysis of energy spectra of elastic backscattered (EBS) proton from Mn, O and Li nuclei and the a-particles energy from the 7 Li(p,a) 4 He nuclear reaction (NR). Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction Many actual environmental problems are consequence of the use of non-renewable and fossil-based energy sources. To sustain growing industrial and societal energy demands in an environmen- tally friendly way, will require the use of clean energy sources such as solar, wind, nuclear, electric batteries, etc. Lithium-ion battery technology offers storage and energy conversion devices with high energy density, power and long life suitable for several new appli- cations like hybrid and electric vehicles [1]. In addition, the lithium- ion battery has become the basis of a huge market for portable de- vices because it offers smaller sizes and longer runtime than other rechargeable technologies as lead acid and nickel-metal hydride [2]. One of the reasons to use lithium ion is its lightness and its high electropositive potential [2]. It is also a strategic material that can be used in other energy applications such as nuclear fusion. Lithium is widely distributed on Earth; the biggest deposits have been found in Bolivia, Argentina, and more recently, in Mexico. Basically, a Li-ion cell consists of a positive and negative elec- trode and an electrolyte between them, which must be ionic con- ductor and electronic insulator. Once positive and negative electrodes are linked by external connector a spontaneous electro- chemical reaction take place, in which chemical energy is trans- formed into electrical energy [3]. A reverse reaction can proceed under an applied electric current. These reactions are known as discharge and charge processes and involve a diffusion of lith- ium-ion to the positive electrode: insertion and extractions, respectively. Some characteristics of the batteries, as rate perfor- mance, are usually limited by positive electrode and several re- searches are in progress to develop major capacitive materials [4]. Current lithium-ion positive electrode material mostly consists of LiCoO 2 that has high cost and toxicity. One attractive material to be used as positive electrode is the LiMn 2 O 4 spinel, with an Fd-3m space group, that has lower cost and toxicity compared to LiCoO 2 . To obtain LiMn 2 O 4 spinel with excellent electrochemical character- istics, several techniques, such as sol–gel, melt-impregnation and solid-state process [5–7] have been developed. Although these methods improve the electrochemical properties of spinel, to some extent, there are still some problems, such a phase transition near to the room temperature and difficult operation or scale-up. The consequence of the phase transition is a fading in the capacity, due to the presence of an undesirable impure phase, and produces a decrease in delivered energy. Therefore, much research is direc- ted towards synthesizing lithium–manganese spinel oxides with characteristics that can overcome these problems. One way to overcome them is the lithium extraction of the LiMn 2 O 4 . This 0168-583X/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2010.12.036 ⇑ Corresponding author. E-mail address: andrade@fisica.unam.mx (E. Andrade). Nuclear Instruments and Methods in Physics Research B 269 (2011) 440–443 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb