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
ACTIVATION OF SEPIOLITE BY VARIOUS ACID TREATMENTS C.Kalaiselvi1, M.Sivakumar2, R.Subadevi3 1,2,3 #120,
Energy Materials Lab, Department of Physics, Alagappa University, Karaikudi- 630003. Tamil Nadu, India. * ( Corresponding Author(s): susimsk@yahoo.co.in (R.Subadevi) ; susiva73@yahoo.co.in (M.Sivakumar)) ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - The rechargeable Li-S battery is an attractive
candidate for the next generation of energy storage device. LiS battery based on redox coupling has high theoretical specific capacity and energy density. Large volumetric expansion of sulfur coupled with polysulphide dissolution during lithiation process is one among the problems faced by Li-S battery. To come across this issue, conducting additive materials are used as a positive electrode with sulfur. In this work, sieved sepiolite has been selected for sulfur based composite material to face the above provocation. Sepiolite is a hydrated magnesium silicate clay mineral with layered chain structure and fibrous morphology. It could be an absorbing material for lithium – sulfur batteries due to its ion transmission channel and large pore volume. Sepiolite was activated with different acid treatment (HCl, H2SO4, and HNO3) to employ as cathode materials, in order to improve cyclability of Li-S batteries. The obtained composites are characterized by using XRD, FT-IR and SEM analyses. In XRD pattern, acid treatment increases the surface area, because it virtually destroys the minerals and produces amorphous silica. The functional vibrations of the prepared composites are analyzed by FT-IR spectra. The fibrous morphology of the particles was observed by SEM images. Key Words: Lithium sulfur battery, energy density, polysulphide, sepiolite, acid treatment,
1. INTRODUCTION
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Sepiolite (Sep) is a hydrated magnesium silicate having the half-unit cell chemical formula of Mg4Si12O30 (OH)4.12H2O[7-9].Sep is categorized in natural clay minerals with the needle-like or fiber-like morphology consisting of several blocks and tunnels which are oriented toward the fiber axis. This has been commonly used in several technological and industrial applications. The surface of sepiolite has a great ability for grafting reactions with organosilanes due to its high content of silanol groups that are very susceptible to the reactions [10]. Many of these applications are based on the good adsorptive, rheological and catalytic properties [11,12]. The development of the porosity and of the number of acid centres and the size of the silica fibres in the solids are characterized as a function of the acid activation. The Lithium-sulfur battery is a liquid electrochemical system, in which the dissolution of lithium polysulfide plays an essential role in the battery performance [6].
2. EXPERIMENTAL WORK
Li-S battery is an electrochemical storage device through electrical energy can be stored in sulfur electrode [1]. These batteries have gained intense attention, because they have a high theoretical energy than that of current Li-ion cells. This is due to the very high specific capacity 1675mAh/g based on two electron reaction [2]. In addition, sulfur is low cost, plenteous, safety and environmental compatibility are some of the most important parameters [3].However, Li-S batteries also bear from numerous tribulations. One among this crisis was high solubility of the intermediate products of lithium polysulfides in the organic electrolyte lowers the consumption of sulfur and hence results in poor cycle performance of the batteries [4]. Sulfur and lithium sulfide © 2017, IRJET
are both insulators, which necessitates the incorporation of conductive additives into the electrodes [5]. To overcome the insulation of sulfur hub on introducing electrical conductive additives are used. Micropores act as the host of the impregnated sulfur and prevent the dissolution of polysulfides. In the present study, sieved sepiolite was used as an additive material to develop the above inherent troubles.
Impact Factor value: 5.181
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2.1. Material preparation: Sepiolite powder was purchased from Sigma-Aldrich, different acids (HCl, H2SO4 and HNO3) from Nice Company, Sulfur Alfa-Aaser. Acid treatment Conc. Hydrochloric acid (5ml) and 10ml of deionised water were mixed vigorously and then getting dilutes hydrochloric acid. The 10ml of dilute HCl were added to the 1 gram of sieved sepiolite material. After that, without ISO 9001:2008 Certified Journal
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