Perfluoroaryl‐elemental sulfur SNAr chemistry in covalent triazine frameworks with high sulfur contents for lithium–sulfur batteries

In order to address the challenges associated with lithium–sulfur batteries with high energy densities, various approaches, including advanced designs of sulfur composites, electrolyte engineering, and functional separators, are lately introduced. However, most approaches are effective for sulfur cathodes with limited sulfur contents, i.e., <80 wt%, imposing a significant barrier in realizing high energy densities in practical cell settings. Here, elemental sulfur-mediated synthesis of a perfluorinated covalent triazine framework (CTF) and its simultaneous chemical impregnation with elemental sulfur via SNAr chemistry are demonstrated. SNAr chemistry facilitates the dehalogenation and nucleophilic addition reactions of perfluoroaryl units with nucleophilic sulfur chains, achieving a high sulfur content of 86 wt% in the resulting CTF. The given sulfur-impregnated CTF, named SF-CTF, exhibits a specific capacity of 1138.2 mAh g−1 at 0.05C, initial Coulombic efficiency of 93.1%, and capacity retention of 81.6% after 300 cycles, by utilizing homogeneously distributed sulfur within the micropores and nitrogen atoms of triazine units offering high binding affinity toward lithium polysulfides

Carbon-Coated SnO2 Nanorod Array for Lithium-Ion Battery Anode Material

Carbon-coated SnO2 nanorod array directly grown on the substrate has been prepared by a two-step hydrothermal method for anode material of lithium-ion batteries (LIBs). The structural, morphological and electrochemical properties were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurement. When used as anodes for LIBs with high current density, as-obtained array reveals excellent cycling stability and rate capability. This straightforward approach can be extended to the synthesis of other carbon-coated metal oxides for application of LIBs

Low dimensional nanostructures of fast ion conducting lithium nitride

As the only stable binary compound formed between an alkali metal and nitrogen, lithium nitride possesses remarkable properties and is a model material for energy applications involving the transport of lithium ions. Following a materials design principle drawn from broad structural analogies to hexagonal graphene and boron nitride, we demonstrate that such low dimensional structures can also be formed from an s-block element and nitrogen. Both one- and two-dimensional nanostructures of lithium nitride, Li3N, can be grown despite the absence of an equivalent van der Waals gap. Lithium-ion diffusion is enhanced compared to the bulk compound, yielding materials with exceptional ionic mobility. Li3N demonstrates the conceptual assembly of ionic inorganic nanostructures from monolayers without the requirement of a van der Waals gap. Computational studies reveal an electronic structure mediated by the number of Li-N layers, with a transition from a bulk narrow-bandgap semiconductor to a metal at the nanoscale

Lithium–Sulfur Battery Electrolytes

The electrolyte is at the very heart of any battery concept physically, but more and more also mentally amongst battery researchers and developers. This is largely due to the growing insight that many problems related to overall efficiency, life-length, and safety often originate in the electrolyte. This is perhaps even more a truth for the Lithium-Sulfur (Li–S) battery technology and hence large efforts are today focused on novel Li–S battery electrolytes — materials as well as concepts. In this chapter we will start by summarizing the similarities and differences in demands and design as compared to the Li-ion battery (LIB) technology, as the latter is more familiar to most readers. We then move to two large sections of liquid and solid electrolytes, respectively, outlining the materials and methods used. In each of the sections we point to a few specific topics and how these are researched today, keeping the comparison with the LIB as a way to more easily understand the unique features/issues/problems that electrolytes for Li–S batteries are facing. The chapter is made at a level and limited to a scope where the open literature is sufficient and plentiful, but of course studying the patent literature and gaining the hidden industry know-how may definitively extend the scope for the interested reader. Overall we hope that after reading this chapter, armed with a basic knowledge of the types of electrolytes and the materials presently in use in Li–S batteries, it will be easier for the reader to understand the needs, limitations, problems, but also the possibilities. This should finally open for suggestions of how to rationally improve the electrolytes with in the end enhanced performance of future Li–S batteries

The effect of curcumin on healing in an animal nasal septal perforation model

Objectives/Hypothesis We investigated the effect of intranasal topical curcumin on nasal septum mucosa wound healing in a nasal septal perforation model produced in rabbits. Study Design Experimental study. Methods Fourteen male New Zealand rabbits were included in the study. For each rabbit, 5-mm-diameter circular perforations were created at 5 mm away from the columella to the nasal septum. Curcumin (study group) and saline (control group) were administered intranasally once daily for 10 days. At the end of the 10th day, the animals were sacrificed and the nasal septum specimens were sent for histological examination. Epithelial regeneration and degeneration, cartilage degeneration and regeneration, presences of fibroblast, eosinophil, acute/chronic inflammatory and giant cells, capillary density, amounts of granulation tissue and collagen, and macroscopic closure rate of perforation parameters were compared in each group. Results Epithelial and cartilage regeneration, and the amounts of collagen and granulation tissue were significantly higher in the curcumin group compared to the control group (P .05). Conclusions Topical application of curcumin improves the wound-healing process of nasal septum perforation in the animal model. Therefore, curcumin can be used as a safe and effective medical agent to prevent the development of septal perforation. Level of Evidence NA Laryngoscope, 201

The Use of Lithium (Poly)sulfide Species in Li–S Batteries

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The Use of Lithium (Poly)Sulfide Species in Li\textendashS Batteries

International audienceEmerging lithium ion (Li-ion) batteries for load levelling and transport is challenging, especially for materials chemistry, and will be a major focus for upcoming years. However, in the longer term, Li-ion batteries (LIBs) cannot deliver high-energy densities and more radical approaches are necessary. There are several options to go beyond this limit and one of the possibilities for achieving longer storage life and high-energy batteries associated with cost and environmental advantages is the lithium\textendash sulfur (Li\textendash S) system which can theoretically offer three to five fold increase in energy density compared with conventional Li-ion cells. Although the Li\textendash S system has interested the battery community for more than five decades, 1 it still faces issues such as poor cycle life, to reach the market place.2 \textcopyright 2017 by World Scientific Publishing Europe Ltd

Rechargeable aqueous electrolyte batteries: from univalent to multivalent cation chemistry

Water based electrolytes enable very high ionic conductivity, and are particularly attractive for high power density batteries. The main advantages of water-based electrolytes are their lower cost and non-flammability, while their principal disadvantage is the limited thermodynamic electrochemical window of water. Yet, the latter is currently being challenged, through the use of highly concentrated electrolytes (“water in salt concept”). Strong research focus is currently placed on rechargeable M-ion batteries (M = Li, Na) mimicking the organic Li-ion or Na-ion batteries, which will despite falling shorter in energy density exhibit cost advantages. Moreover, they should be expected to deliver very attractive power densities. The main challenge at this stage is the development of new negative electrodes able to operate at lower potentials. A more challenging topic is divalent ion concepts (M = Zn) using a Zn metal anode which could, in principle, deliver higher energy density, but for which issues still remain related to (i) developing appropriate positive electrode materials for reversible Zn ion insertion and (ii) side reactions involving mostly H+ or OH− species, which are not yet mastered