460686 Nanostructured Transition Metal Nitrides As Promising Cathode Materials for Lithium Sulfur Batteries

Wednesday, November 16, 2016: 4:35 PM
Mason (Hilton San Francisco Union Square)
Negar Mosavati, Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, MI, Steven Salley, Chemical Engineering and Materials Science, Wayne State University, Detroit, MI and Simon Ng, Chemical Engg., Wayne State University, Detroit, MI

The Lithium Sulfur (Li-S) battery system is considered as one of the most promising options for electric vehicles to achieve a higher driving range, due to their higher energy density compared to conventional lithium ion batteries. However, there are some challenges facing Li−S battery commercialization, such as: low active material utilization due to the insulating nature of sulfur, high self-discharge products due to redox shuttle reactions, and high rate of capacity fade due to the irreversible deposition of lithium sulfide (Li2S, Li2S2) on the cathode and Li anode surface. Much of the research has focused on enhancing carbon materials’ electrical conductivity and ability to absorb and accommodate polysulfides in order to enhance Li/S battery cycleability and capacity performance.

In this research, we investigated different transitional metal nitrides such as: Tungsten nitride (WN), Molybdenum Nitride (Mo2N) and Vanadium Nitride (VN) as novel cathode materials for Li/dissolved polysulfide batteries. Transition metal nitrides are well known materials for super-capacitors and lithium-ion batteries due to their high reversible insertion and extraction of ionic species and the capability of storing lithium by the intercalation mechanism. In order to obtain a better understanding of the electrochemical performance and the mechanisms underlying polysulfides redox reactions of all cathode materials, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analysis, in addition to electrochemical spectra (EIS) and cyclic voltammetry (CV) measurement have been applied. Among these metal nitrides, WN exhibited the most promising capacity performance as it can adsorb lithium polysulfides effectively and transfer electrons in a facile manner. As a result, the active material and surface area loss were reduced and the capacity and capacity retention of the cell were enhanced.

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