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 53 INVESTIGATIONS ON PHYSICAL PROPERTIES OF SULFUR BASED COMPOSITE CATHODES IN LITHIUM SULFUR BATTERY FABRICATION G.Radhika 1 , K.Krishnaveni 2 , R.Subadevi 3 , M.Sivakumar 4 1,2,3,4 #120, Energy Materials Lab, Department of Physics, Alagappa University, Karaikudi-630 003, Tamil Nadu, India. (* Corresponding Author: susiva73@yahoo.co.in (M.Sivakumar)) ------------------------------------------------------------------------***---------------------------------------------------------------------- Abstract: Sulfur is a promising cathode material with a high theoretical capacity of 1672 mAh g -1 , but the challenges of the low electrical conductivity of sulfur and the high solubility of polysulfide intermediates still hinder its practical application. The use of conductive carbon framework is efficient and effective to obtain advanced composite cathodes for lithium–sulfur batteries. However, the loading amount of sulfur less than 70 wt% induces a limited energy density, which hinders the practical application of lithium–sulfur batteries. Herein, a scalable and one-step method is employed for carbon nanotube/sulfur composite cathode, in which aligned CNTs served as interconnected conductive frameworks to accommodate sulfur. The results of the SEM and XRD measurements reveal that the CNTs serve as the cores and are dispersed individually into the sulfur matrices; the sulfur with a high loading content was efficiently utilized for a lithium–sulfur cell with a much improved energy density. Key Words: sulfur battery; carbon nanotube; XRD; SEM; energy density. 1. INTRODUCTION Lithium-ion batteries are being increasingly used for large-scale energy storage systems, driven by the growth of markets such as electric vehicles and large scale energy storage systems [1, 2]. Their practical use in these new applications is still challenging, however, as long as the attainable energy density of Li-ion batteries is limited to their current forms. In this respect, intercalation-based cathode materials have almost approached their theoretical energy density limit [3-5]. It is anticipated that breakthroughs will probably come from chemical transformation or conversion chemistry, similar to the evolution of anodes from carbonaceous materials that function on the basis of intercalation chemistry, to conversion chemistry based on metal oxides or lithium alloys [6]. Li-S batteries become one of the most attractive candidates for the next generation high-energy rechargeable battery because of their high theoretical specific capacity (1675 mAh g -1 ), high theoretical energy density (2600 Wh kg -1 ), and economic cost [7-10]. Additionally, sulfur is abundant, low cost, and environmentally friendly. Therefore, lithium sulfur batteries have great potential for the next generation of high energy density lithium batteries. However, the lithium/sulfur battery systems investigated previously have some critical problems [11-13]. First, elemental sulfur is electrically and ironically insulating at room temperature, which leads to poor electrochemical performance and the low utilization of sulfur in the cathode. Second, Li2S and other insoluble compounds are generated and cover the active compounds during cycling, which inhibit access to lithium ions. Third, since the discharge process of the battery is composed of many steps and generates various forms of soluble intermediate lithium polysulfide, the liquid electrolyte can dissolve and cause a rapid irreversible loss of sulfur active materials over repeat cycles. Furthermore, the spread of these polysulfide’s to the anode can lead to the shuttle mechanism and this may cause more serious capacity loss. Consequently, the battery suffers because of the low utilization of active materials and because of poor cycle life. Over the past few decades, these above issues have been mitigated by moving from conventional electrodes to sulfur−carbon composites, in which the elemental sulfur is efficiently trapped within protecting carbon matrixes of various configurations (such as grapheme, [14,15] porous carbon, [16] and CNTs [17] ). Alternatively, it has also been proposed to contain sulfur in hollow carbon nanoparticles, as a method of targeted design of porous materials that could; allow for higher sulfur content while still retaining the benefits of a porous carbon shell that inhibits polysulfide dissolution [18-19]. Such mesoporous hollow carbon capsules might offer advantages over other porous