Rechargeable magnesium-sulfur (Mg/S) batteries are considered a promising energy storage devices for grid-scale applications due to their high theoretical energy density, safety, and low cathode cost. However, the Mg/S batteries suffer from the low practical energy density mainly arising from the rapid dissolution of polysulfides and slow reaction kinetics between Mg and solid-phase sulfur. In this regard, we have introduced here the magnesium polysulfide (MgSx) catholyte as a liquid-phase active material to conquer the sluggish redox kinetics of Mg/S batteries. A polyaniline-coated carbon cloth (CC@PANI) has been incorporated as a current collector and a reservoir for magnesium-polysulfide(MgSx) catholyte. The MgSx containing CC@PANI cathode (i.e., CC@PANI@MgSx cathode) exhibits an initial reversible specific capacity of 514 mA h g−1 and retains 428 mA h g−1 after 25 cycles. The effect of MgSx catholyte on the electrochemical performance of the Mg/S batteries have been closely investigated through post-cycling characterization of Mg anode and computational studies. Besides, the phase transition of sulfur during magnesiation a complete reaction has been studied in the current report. © 2020

Priya Sudhir Johari

Physics

(SoNS) School of Natural Sciences

Muthuraj D.

Pandey M.

Krishna M.

Ghosh A.

Sen R.

Mitra S.

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

Journal of Power Sources

Volume expansion and elastic softening of the Sn anode on lithiation result in mechanical degradation and pulverization of Sn, affecting the overall performance of Li-Sn batteries. It can, however, be overcome with the help of void space engineering by using a LixSn phase as the prelithiated anode, where an optimal value for x is desired. Currently, Li4.25Sn is known as the most lithiated Li-Sn compound, but recent studies have shown that at high pressure, several exotic and unusual stoichiometries can be obtained that may even survive decompression from high-to-ambient pressure with improved mechanical properties. With a belief that hydrostatic pressure may help in realizing Li-richer (x &gt; 4.25) Li-Sn compounds as well, we performed extensive calculations using an evolutionary algorithm and density functional theory to explore all stable and low-energy metastable Li-Sn compositions at pressures ranging from 1 atm to 20 GPa. This not only helped us in enriching the chemistry of a Li-Sn system, in general, but also in improving our understanding of the reaction mechanism in Li-Sn batteries, in particular, and guiding a route to improve the performance of Li-ion batteries through synthesis of Li-rich phases. Besides the experimentally known Li-Sn compounds, our study reveals the existence of five unreported stoichiometries (Li8Sn3, Li3Sn1, Li4Sn1, Li5Sn1, and Li7Sn1) and their associated crystal structures at ambient and high pressure. Although Li8Sn3 has been identified as one of the most stable Li-Sn compound in the entire pressure range (1 atm-20 GPa) with R3m symmetry, the Li-rich compounds like Li3Sn1-P2/m, Li4Sn1-R3m, Li5Sn1-C2/m, and Li7Sn1-C2/m are predicted to be metastable at ambient pressure and found to get thermodynamically stable at high pressure. Here, the discovery of Li5Sn1 and Li7Sn1 opens up the possibility to integrate them as a prelithiated anode for efficiently preventing electrochemical pulverization, as compared to the experimentally known highest lithiated compound, Li17Sn4. © 2017 American Chemical Society.

ACS Applied Materials and Interfaces

Understanding the Lithiation of the Sn Anode for High-Performance Li-Ion Batteries with Exploration of Novel Li-Sn Compounds at Ambient and Moderately High Pressure

ACS Energy Letters

Free-Radical Catalysis and Enhancement of the Redox Kinetics for Room-Temperature Sodium–Sulfur Batteries

Role of Cu current collector on electrochemical mechanism of Mg–S battery

Advanced Functional Materials

Rechargeable Magnesium–Sulfur Battery Technology: State of the Art and Key Challenges

A free-standing reduced graphene oxide aerogel as supporting electrode in a fluorine-free Li2S8 catholyte Li-S battery

Magnesium polysulfide catholyte (MgSx): Synthesis, electrochemical and computational study for magnesium-sulfur battery application