Bis[1,3-bis­(2-cyano­phen­yl)triazenido]mercury(II)

In the title compound, [Hg(C14H8N5)2], the central atom is four-coordinated by two bidentate 1,3-bis­(2-cyano­phen­yl)triazenide ligands in a distorted square-planar geometry. The asymmteric unit is composed of one ligand molecule and one HgII ion, which is disordered over two sites, one lying on an inversion center and the other on a general position with site-occupancy factors of 0.2378 (7) and 0.3811 (7), respectively. The monomeric mol­ecules of the complex are linked into pairs through non-classical C—H⋯N hydrogen bonds. The resulting dimeric units are assembled by translation along the crystallographic c axis into chains linked through secondary π–π inter­actions [centroid–centroid distances = 3.685 (2) and 3.574 (2) Å], as well as C—H⋯π stacking inter­actions, resulting in a two-dimensional architecture

Effect of LiNO3 additive and pyrrolidinium ionic liquid on the solid electrolyte interphase in the lithium sulfur battery

The lithium-sulfur (Li-S) battery in which the ionic liquid (IL) C4mpyr-TFSI is a major component of the electrolyte has attracted much attention by researchers due to the ability of the IL to suppress the polysulfide shuttle effect, combined with advantageous properties of thermal, chemical and electrochemical stability. In a largely parallel stream of research, LiNO3 has come to be known as an additive for improving Li-S battery performance through its influence on protecting the lithium anode and beneficial interaction with the polysulfide shuttle. In this work a deeper understanding is sought of the combined effects of LiNO3 and C4mpyr-TFSI on the factors that impact Li-S cell performance. Specifically, we investigate the formation of the protective surface film on lithium anode and results are compared with those for a typical organic electrolyte for the Li-S battery, DOL:DME. Electrochemical impedance spectroscopy (EIS) confirms that the LiNO3 additive is vital to achieving acceptable levels of performance with the organic electrolyte. Although LiNO3 improves the performance of a battery assembled with IL containing electrolyte, it shows a higher impact in the organic electrolyte based battery. Furthermore X-ray photoelectron spectroscopy (XPS) spectra confirm the participation of C4mpyr-TFSI on the formation of the interphase layer on the anode

Suppressed Polysulfide Crossover in Li–S Batteries through a High-Flux Graphene Oxide Membrane Supported on a Sulfur Cathode

Utilization of permselective membranes holds tremendous promise for retention of the electrode-active material in electrochemical devices that suffer from electrode instability issues. In a rechargeable Li–S batterya strong contender to outperform the Li-ion technologymigration of lithium polysulfides from the sulfur cathode has been linked to rapid capacity fading and lower Coulombic efficiency. However, the current approaches for configuring Li–S cells with permselective membranes suffer from large ohmic polarization, resulting in low capacity and poor rate capability. To overcome these issues, we report the facile fabrication of a high-flux graphene oxide membrane directly onto the sulfur cathode by shear alignment of discotic nematic liquid crystals of graphene oxide (GO). In conjunction with a carbon-coated separator, the highly ordered structure of the thin (∼0.75 μm) membrane and its inherent surface charge retain a majority of the polysulfides, enabling the cells to deliver very high initial discharge capacities of 1063 and 1182 mAh g_electrode^–1 for electrodes with 70 and 80% sulfur content, respectively, at the practical 0.5 C rate. The very high sulfur utilization and impressive capacity retentions of the high sulfur content electrodes result in some of the highest performance metrics in the literature of Li–S (<i>e.g.</i>, electrode capacity of 835 mAh g_electrode^–1 after 100 cycles at 0.5 C with a sulfur content of 80%). We show that the structural order of the shear-aligned GO membrane is key in maintaining good kinetics of the charge transfer processes in Li–S batteries