International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Special Issue: 09 | Sep -2017
p-ISSN: 2395-0072
www.irjet.net
One Day International Seminar on Materials Science & Technology (ISMST 2017) 4th August 2017 Organized by
Department of Physics, Mother Teresa Women’s University, Kodaikanal, Tamilnadu, India
OPTIMIZATION OF LITHIUM CONCENTRATION IN LITHIUM IRON ORTHOSILICATE VIA POLYOL ROUTE K.Diwakar1, R.Dhanaladkshmi1,2, P.Rajkumar1, R.Subadevi1, M.Sivakumar1 1#120,
Energy Materials Lab, Department of Physics, Alagappa University, Karaikudi-630 003, Tamil Nadu, India. of Physics, Thiagarajar College, #139-140, Kamarajar Salai, Madurai - 625009, Tamil Nadu, India. (* Corresponding Author: susiva73@yahoo.co.in (M.Sivakumar)) ---------------------------------------------------------------------***--------------------------------------------------------------------2Department
Abstract - In recent decade, silicate based cathode
materials have received a great attention due to its specific capacity (~330 mAh/g)(Ni et al. 2017). Hence, it is used as a Lithium intercalated electrode in LIBS. In this study, Lithium iron orthosilicate cathode materials were prepared by polyol method and studied the effect of concentration of Lithium in Li(2+x)FeSiO4/C composites (0 less than or equal x less than or equal 0.5) toward its physical property of Lithium iron orthosilicate. The as-prepared material was characterized by X-ray diffraction, FTIR, Raman and TEM. Structural determination was carried out with the help of powder XRD. Carbon coated on the as- synthesized materials was evident through D and G bands of Raman analysis. FTIR provides the valuable information on the stretching and bending vibrations of Si-O and Fe-O. Finally, the morphology of the as prepared sample shows nano sized crystallites. From the investigation, x=0.5 mol concentration of lithium has been optimized in terms of the structural aspect. Key Words: cathode, Lithium ion batteries, orthosilicate, polyol method, physical property.
1. INTRODUCTION Development and promotion of Lithium Ion Batteries (LIB) have widely dominated in commercial application for store and utilize energy in terms of electric, on account of its peculiar properties, LFSted as high energy conversion efficiency, low self discharge, better cycle life and light weight[1,2]. Choice of the cathode materials is very essential factor in LIBs to fix the price, control level of toxicity, improve safety problems and predict the capacity of battery. Apart from small scale usage, LIBs are frequently used in large scale applications such as hybrid electric vehicles, renewable power plant to store the intermediate energy[3]. More commercialized cathode materials for LIBs are layered, spinel and olivine structure. The presence of polyanionic compound in the cathode materials provides good thermal stability to the LIB, because of strong covalent bond interaction between Si-O. At the same time, Lithium transition metal orthosilicate (Li2FeSiO4) was considered a potential cathode material on account of its environmental benignancy, abundant source materials, inexpensive, structural stability and high theoretical capacity [(330 mAh © 2017, IRJET
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g-1) than LiFePO4 (170 mAh g-1) due to the probability which takes place multielectron reaction]. Significantly, practical electrochemical performance of Li2FeSiO4 was not considerably too good due to its low intrinsic electronic conductivity and slow lithium ion diffusion which inhibits its future applications in electric vehicles and plugin electric vehicles[4]–[7]. The improvement in the electronic conductivity was a major problem identified by many researchers. In order to achieve better electronic conductivity and lithium mobility three strategies can be suggested, conductive carbon coating on the active materials, particle size reduction and isovalent cation doping. Individually and merging all the strategies, these methods have been used to improve the electrochemical performance of Lithium iron orthosilicate. From their reports carbon coating and particle size reduction can effectively improve the electrochemical performance of LFS. Nishimura et al. [8] was intensively investigated the valid structure of LFS by combined the results of HR-XRD and TEM approaches. S. Zhang et al.[9] the LFS powder have nano distribution of crystallites about 80 nm, this attributes that nano size crystallites can be yielded molecular level mixing of starting materials. Decreasing the particle size of polyanion materials can shorten the diffusion path of Lithium ion. From the report of S. Zhang [10], comparative study between Li2Fe0.97Mg0.03SiO4 and Li2FeSiO4 was carried to understand the electrochemical performance and structural properties of the cathode material. Particularly, the role of dopant can enhance the structural stability, lithium ion diffusion capacity and reduces the electrochemical impedance of the material. V. Aravindan et al.[11] demonstrated that the composite electrode comprising of 42 wt% of carbon improve the electronic conduction of electrode. In this paper, an attempt was made to prepare nanosized Lithium iron orthosilicate/C by increase the concentration of Lithium (0.5) via polyol route, TTEG as a solvent. The structural and morphological properties of the prepared samples were investigated with the aid of XRD, FTIR, Raman Spectra and TEM.
2. Material and Method LFS nanocrystallites were synthesized by polyol route using TTEG as a solvent[12]. Here, stoichiometric amounts of ISO 9001:2008 Certified Journal
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