A novel dicationic room temperature ionic liquid, 1,1′-(5,14-dioxo-4,6,13,15-tetraazaoctadecane-1,18diyl) bis(3-(sec-butyl)-1H-imidazol-3-ium) bis((trifluoromethyl)-sulfonyl) imide has been synthesized and fully characterized. Its thermal and electrochemical analyses along with transport properties have been studied. We propose it as a potential nominal additive to the commonly used conventional organic carbonate electrolyte mixture and study its adaptability in Lithium-ion batteries which are the prime power sources for ultraportable electronic devices. We have compared the performance characteristics of the full cells made without and with this ionic liquid. The cells comprise lithium nickel cobalt manganese oxide cathode, graphite anode and ethylene carbonate-dimethyl carbonate (1:1, v/v + Lipf 6) mixture electrolyte with nominal amount of ionic liquid as additive. The major concern with conventional electrolytes such as degradation of the materials inside batteries has been addressed by this electrolyte additive. Additionally, this additive is safer at relatively higher temperature. In its presence, the overall battery life is enhanced and it shows good cycling performance and coulombic efficiency with better discharge capacities (22% higher) after 100 cycles. Even after the increase in current rate from 10 mA/g to 100 mA/g, the cell still retains around 73% of capacity. Lithium-ion batteries (LIBs) 1,2 which possess high energy density have been in high demand as energy storage solution in lot of portable electronic gadgets/devices such as mobile phones and laptops. Further, they have the potential to serve as the most promising energy storage options for the next generation electric vehicles and smart grid technology 3,4. The enhancement of operational safety in LIBs has been a major concern for last few decades. The stringent requirement for enhanced safety compels extensive studies those are focused towards the improvement in their safety and stability for long cycles without compromising on their performance 5. The commercial batteries available in the market are mainly fabricated with organic carbonates along with lithium hexafluorophosphate (LiPF 6) as electrolytes 6-8 , which are prone to ignition or even explosion when cells are damaged or exposed to high temperatures. Safety should be the core of the design philosophy of a battery 9-11. In an excellent review, Zhang has meticulously discussed the effect of electrolyte additives to enhance the performance of LIBs by many fold like facilitating the formation of SEI, increase in cycling of LIB, enhancing thermal stability as compared to carbonate based organic electrolytes, as a cathode protecting material and even improving the physical properties of the electrolytes 10. Han et al. 12 and Kang et al. 13 showed that additives can enhance the electrochemical cell performances of LIBs. During the cyclical operations of these cells, the instability of the Li/electrolyte interface might end up into short-circuiting of the cells due to dendrite formation on...
Abstract:Compounds based on the [3 × 3] nonamanganese(II) square grid motif and featuring additional manganese(II) ions linked to the grid core were isolated through a strict self-assembly approach. Extended tritopic picolinic dihydrazide ligands were used, which contain terminal ester groups and differ in the R substituent on the para position of the central pyridine ring (H 2 L 1 , R = OCH 3 ; H 2 L 2
We herein report a structurally characterized Schiff base ligand, L formed by the condensation of 1,1-bis-[2-hydroxy-3-acetyl-5-methylphenyl]methane with 2-picolyl amine. It utilizes the three signalling mechanisms ESIPT, chelation enhanced fluorescence (CHEF) and C=N isomerization to serve as a "Turn-On" fluorescence chemosensor for Al 3+ . L has high selectivity for Al 3+ in MeOH. Reversible nature of this chemosensor makes it cost effective. This joins the rare family of ditopic fluorescent chemosensor. When this Schiff-base receptor was treated with Al 3+ salt in MeOH, the fluorescence intensity abruptly increased. Other metal ions did not show such significant effect on the fluorescence. Detection limit for this chemosensor was found to be 0.7 μM.
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