International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 04 Special Issue: 09 | Sep -2017 www.irjet.net p-ISSN: 2395-0072 One Day International Seminar on Materials Science & Technology (ISMST 2017) 4 th August 2017 Organized by Department of Physics, Mother Teresa Women’s University, Kodaikanal, Tamilnadu, India © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 49 SYNTHESIS AND STRUCTURAL ANALYSIS OF NaFePO4 NANOCOMPOSITE FOR SODIUM ION BATTERIES V. Priyanka 1 , R.Subadevi 2 , M.Sivakumar 3 * 1,2,3 #120, Energy Materials Lab, Department of Physics, Alagappa University, Karaikudi-630 003, Tamil Nadu, India. (* Corresponding Author: susiva73@yahoo.co.in (M.Sivakumar) ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Sodium-ion batteries (SIBs) have attracted attention as a competitive alternative to LIBs because of their low cost and the wide availability of sodium resources. Polyanionic Transition-metal phosphates with open- framework structures have been subject to growing scientific interest as electrode materials for sodium-ion batteries. This is mainly due to the remarkable structural and thermal stabilities of this class of materials. In particular, iron-based phosphate compounds such as NaFePO4 have been intensively studied as positive electrode materials for sodium ion batteries. The material is synthesized via sol-gel and solid state methods and its structural studies have been analyzed. The crystalline nature of the material was analyzed using X-ray diffraction for both the methods. The intensity of the peaks of NaFePo4 prepared by sol-gel method seems to be higher than solid state method. The presence of functional groups and vibrational peaks of PO4 3- groups were identified using Fourier transform infra – red spectroscopy. The raman shift for Fe-O vibrations was investigated by laser raman spectroscopy. The morphology and the microstructure of the sample were studied using scanning electron microscopy. The particle size was found to between 100-150nm. The results revealed that as prepared NaFePO4 nano composite prepared by sol-gel method serves as promising cathode material for sodium ion batteries. Key Words: Sodium ion batteries, NaFePO4, Cathode material, Structural studies, Sol-gel method. 1. INTRODUCTION Vehicle electrification is one of the most significant solutions that address the challenges of fossil fuels depletion, global warming, CO2 pollution and so on. Sodium is the fourth most abundant element in the earth’s crust and United States alone has huge reserves of 23 billion tons of soda ash. Therefore, sodium-ion chemistry is an attractive and alternative energy storage technology to replace LIB because of its abundance (uniformly distributed everywhere across the world) and inexpensive raw material cost for preparing sodium-based electrode materials [1, 2]. Sodium has a redox potential of ENa + /Na = −ʹ.7ͳ V versus standard hydrogen electrode; it is only 0.3 V above that of lithium indicates that rechargeable cells based on sodium chemistry are one of the promising energy storage technologies. Besides these advantages, so many sodium-based energy storage technologies are available, such as, sodium– sulfur cells, sodium–air cells, ZEBRA cells and sodium ion cells [3]. As compared with other sodium-based storage technologies, sodium ion cells possess advantages such as high voltage (approximately 3.6 V), operating well even at room temperature, inexpensive electrode and electrolyte-active materials and, more significantly, easy portability[4]. In view of safety and cost concerns, polyanion-based compounds have been explored for LIBs during the last two decades. These include olivine phosphates [LiMPO4 (M=Fe, Mn, Ni, etc.)], tavorite fluorophosphates and fluorosulfates[5]. 2. EXPERIMENTAL 2.1 Method 1(S1): In solid state method all the raw materials such as sodium acetate, Iron(II) sulphate and Ammonium dihydrogen phosphate are taken in the stiochiometric ratio. It is ball milled for 4 hours and dried at 150 ° C for 12 hours. After ball milling the raw materials are calcined at 350°C for 4 hours. Again it is calcined at 600 ° C for 6 hours by passing argon gas. 2.2 Method 2(S2): In sol gel method, Initially sodium acetate and citric acid were dissolved in 20ml of de-ionized water under magnetic stirring at 80°C. Then a stiochiometric amount of Iron(II) sulphate and Amonium dihydrogen phosphate were added to the above solution and stirred until a gel was formed. Once the formation of gel occurs it is transferred into a petridish and dried at 120°C for 10 hours under vacuum to form xerogel. Finally, the xerogel was finely ground and then calcined at 800°C for 10 hours under argon atmosphere. 2.3 Characterization: To find out the crystalline phase structure of the as-prepared materials, powder X-ray