Effect of nanosized Mg 0.6 Ni 0.4 O prepared by self-propagating high temperature syn- thesis on sulfur cathode performance in Li/S batteries Yongguang Zhang a , Zhumabay Bakenov b , Yan Zhao a , Aishuak Konarov a , The Nam Long Doan a , Kyung Eun Kate Sun a , Assiya Yermukhambetova b , P. Chen a, ⁎ a Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L3G1 b School of Engineering, Nazarbayev University, 53 Kabanbay Batyr Avenue, Astana 010000, Kazakhstan abstract article info Article history: Received 8 January 2012 Received in revised form 29 August 2012 Accepted 13 October 2012 Available online 22 October 2012 Keywords: Self-propagating high temperature synthesis Mg 0.6 Ni 0.4 O Sulfur cathode additive Lithium–sulfur battery Nanostructured magnesium nickel oxide Mg 0.6 Ni 0.4 O was successfully synthesized by self-propagating high temperature synthesis (SHS) followed by heat treatment. The effect of the precursor composition and calci- nation temperature on the Mg 0.6 Ni 0.4 O powder properties was investigated. These particles were used as an additive to prepare S/Mg 0.6 Ni 0.4 O composite via ball-milling with sulfur. The composite preparation condi- tions were optimized to achieve the higher specific surface area without compromising the sample crystallin- ity. The SEM observation revealed that the sulfur morphology was drastically changed by the Mg 0.6 Ni 0.4 O addition, from smooth to rough agglomerated particles. This change has enhanced the electrochemical performance of the composite cathode. Cyclic voltammetry and charge–discharge tests demonstrated en- hanced reversibility and high sulfur utilization in a Li/S cell with S/Mg 0.6 Ni 0.4 O cathode, delivering about 850 mAh g -1 of reversible capacity at the initial cycle. The effect of the Mg 0.6 Ni 0.4 O heat treatment temper- ature on the S/Mg 0.6 Ni 0.4 O cycling performance was also investigated. The cathode with Mg 0.6 Ni 0.4 O calcined at 700 °C exhibited enhanced capacity retention which could be due to its high specific surface area and nanosized structure. © 2012 Published by Elsevier B.V. 1. Introduction New energy sources are vital for the existence and sustainable de- velopment of our modern society. Currently, fossil fuels have met al- most all of the energy demands of mankind. However, the limited resources of fossil fuels or oil, which may last for only a few more de- cades, and environmental impact of burning fossil fuels call for clean- er and renewable energy sources, such as wind and solar energies [1,2]. One problem for those energies is the fluctuation of the energy input/output, which requires reliable, low cost and environmentally friendly, large scale energy storage systems [3,4]. Lithium-ion batte- ries are the most promising candidate for these applications; howev- er, current cathode materials, such as those based on transition metal oxides and phosphates, have an inherent theoretical capacity limit of 300 mAh g -1 , and a maximum practically usable capacity of only 210 mAh g -1 has been reported [5–8]. Therefore, elemental sulfur (S) is a more attractive candidate due to its low cost, environmental harmlessness and a highest theoretical capacity among known cath- ode materials of 1672 mAh g -1 and theoretical specific energy densi- ty of 2600 Wh kg -1 [9]. However, because of the insulating nature of S, large volume changes during lithium reaction processes and the solubility of polysulfides, as charge–discharge reaction products, into the liquid electrolytes, the practical application of S as a cathode active material in lithium rechargeable batteries has not been suc- cessful yet. Much effort has been dedicated to improve the Li/S system, and various types of conductive carbon materials [6,10–13] and conduc- tive polymers [14–17] have been used in order to both enhance the electronic conductivity of the cathode composites and limit the disso- lution of polysulfides into the electrolytes. Song et al. [18] introduced the use of nanosized Mg 0.6 Ni 0.4 O prepared by a sol–gel method as an electrochemically inactive additive to a sulfur cathode. It was con- cluded that the nanosized Mg 0.6 Ni 0.4 O had not only the polysulfide adsorption effect but also exhibited the catalytic effect towards the Li/S redox reactions. The initial specific discharge capacity of 1185 mAh g -1 could be achieved at 0.1 C galvanostatic cycling. How- ever, the S content in the composite cathode was very low reaching only 16 wt.% and too much an amount of Mg 0.6 Ni 0.4 O (12 wt.%) was added into the composite cathode. Despite the convenience of the sol–gel method to synthesize nanosized Mg 0.6 Ni 0.4 O particles, it is a time consuming technique, which results in a high content of the side products, such as oxynitride, causing dangerous environmental pollution. Therefore, the development of a simpler method to prepare nanosized Mg 0.6 Ni 0.4 O is necessary. Furthermore, the reported con- tent of sulfur [18] is not acceptable for practical batteries because it cannot provide sufficient gravimetrical capacity of the battery. Powder Technology 235 (2013) 248–255 ⁎ Corresponding author. Tel.: +1 519 888 4567x35586; fax: +1 519 746 4979. E-mail address: p4chen@uwaterloo.ca (P. Chen). 0032-5910/$ – see front matter © 2012 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.powtec.2012.10.023 Contents lists available at SciVerse ScienceDirect Powder Technology journal homepage: www.elsevier.com/locate/powtec