FTIR study of ion dissociation in PMMA based gel electrolytes containing ammonium triflate: Role of dielectric constant of solvent

Room temperature, ultrafast and one-step synthesis of highly fluorescent sulfur quantum dots probe and their logic gate operation

The direct and rapid conversion of abundant and cheap elemental sulfur into fluorescent sulfur quantum dots (SQDs) at room temperature is a critical and urgent challenge. Conventional synthesis methods require high temperatures, high pressures, or specific atmospheric conditions, making them complex and impractical for real applications. Herein, we propose a simple method for synthesizing SQDs simply by adding H2O2 to an elemental sulfur-ethylenediamine (S-EDA) solution at room temperature. Remarkably, within a mere 10 min, SQDs with a photoluminescence quantum yield of 23.6 % can be obtained without the need for additional steps. A comprehensive analysis of the mechanism has demonstrated that H2O2 is capable of converting Sx2- ions generated in the S-EDA solution into zero-valent sulfur atoms through oxidation. The obtained SQDs can be utilized as a fluorescent probe for detection of tetracycline (TC) and Ca2+ ions with the limit of detection (LOD) of 0.137 μM and 0.386 μM respectively. Moreover, we have developed a sensitive logic gate sensor based on SQDs, harnessing the activated cascade effect to create an intelligent probe for monitoring trace levels of TC and Ca2+ ions. This paper not only presents a viable approach for ultrafast and scalable synthesis of SQDs at room temperature, but also contributes to the efficient utilization of elemental sulfur resources.

Unveiling the Mysteries: Acetonitrile's Dance with Weakly-Solvating Electrolytes in Shaping Gas Evolution and Electrochemical Performance of Zinc-ion Batteries

Aqueous Zn-metal battery (AZMB) is a promising candidate for future large-scale energy storage with commendable capacity, exceptional safety characteristics, and low cost. Acetonitrile (AN) has been widely used as an effective electrolyte constituent to improve AZMBs' performance. However, its functioning mechanisms remain unclear. In this study, we unveiled the critical roles of AN in AZMBs via comparative in situ electrochemical, gaseous, and morphological analyses. Despite its limited ability to solvate Zn ions, AN-modulated Zn-ion solvation sheath with increased anions and decreased water achieves a weakly-solvating electrolyte. As a result, the Zn||Zn cell with AN addition exhibited 63 times longer cycle life than cell without AN and achieved a 4 Ah cm-2 accumulated capacity with no H2 generation. In V2O5||Zn cells, for the first time, AN suppressing CO2 generation, elevating CO2-initiation voltage from 2→2.44 V (H2: 2.43→2.55 V) was discovered. AN-impeded transit and Zn-side deposition of dissolved vanadium ions, known as "crosstalk," ameliorated inhomogeneous Zn deposition and dendritic Zn growth. At last, we demonstrated an AN-enabled high-areal-capacity AZMB (3.3 mAh cm-2) using high-mass-loading V2O5 cathode (26 mg cm-2). This study shed light on the strategy of constructing fast-desolvation electrolytes and offered insights for future electrolyte accommodation for high-voltage AZMB cathodes.

Molecular Weight Enables Fine-Tuning the Thermal and Dielectric Properties of Polymethacrylates Bearing Sulfonyl and Nitrile Groups as Dipolar Entities

In this work, polymethacrylates containing sulfonyl and nitrile functional groups were successfully prepared by conventional radical polymerization and reversible addition-fragmentation chain-transfer polymerization (RAFT). The thermal and dielectric properties were evaluated, for the first time, considering differences in their molecular weights and dispersity values. Variations of the aforementioned properties do not seem to substantially affect the polarized state of these materials, defined in terms of the parameters ε'_r, ε"_r and tan (δ). However, the earlier appearance of dissipative phenomena on the temperature scale for materials with lower molecular weights or broader molecular weight distributions, narrows the range of working temperatures in which they exhibit high dielectric constants along with low loss factors. Notwithstanding the above, as all polymers showed, at room temperature, ε'_r values above 9 and loss factors below 0.02, presenting higher dielectric performance when compared to conventional polymer materials, they could be considered as good candidates for energy storage applications.

Flame retardant polyphosphoester copolymers as solid polymer electrolyte for lithium batteries

Solid-state lithium batteries are considered one of the most promising battery systems due to their high volumetric energy density, in this work a flame retarded polymer electrolyte is proposed.

TiO2/GO-coated functional separator to suppress polysulfide migration in lithium-sulfur batteries

Lithium-sulfur batteries render a high energy density but suffer from poor cyclic performance due to the dissolution of intermediate polysulfides. Herein, a lightweight nanoporous TiO₂ and graphene oxide (GO) composite is prepared and utilized as an interlayer between a Li anode and a sulfur cathode to suppress the polysulfide migration and improve the electrochemical performance of Li/S batteries. The interlayer can capture the polysulfides due to the presence of oxygen functional groups and formation of chemical bonds. The hierarchically porous TiO₂ nanoparticles are tightly wrapped in GO sheets and facilitate the polysulfide storage and chemical absorption. The excellent adhesion between TiO₂ nanoparticles and GO sheets resulted in enhanced conductivity, which is highly desirable for an efficient electron transfer process. The Li/S battery with a TiO₂/GO-coated separator exhibited a high initial discharge capacity of 1102.8 mAh g^-1 and a 100th cycle capacity of 843.4 mAh g^-1, which corresponds to a capacity retention of 76.48% at a current rate of 0.2 C. Moreover, the Li/S battery with the TiO₂/GO-coated separator showed superior cyclic performance and excellent rate capability, which shows the promise of the TiO₂/GO composite in next-generation Li/S batteries.

Study of PVAc-PMMA-LiCl polymer blend electrolyte and the effect of plasticizer ethylene carbonate and nanofiller titania on PVAc-PMMA-LiCl polymer blend electrolyte

lithium ion conducting polymer electrolyte is one of the essential components of modern rechargeable lithium batteries because of its good interfacial contact with electrodes and effective mechanical properties. A solid lithium ion conducting polymer blend electrolyte is prepared using poly (vinyl acetate) (PVAc) and poly (methyl methacrylate) (PMMA) polymers with different molecular weight percentages (wt%) of lithium chloride (LiCl) by the solution casting technique with tetrahydrofuran as a solvent. The polymer electrolytes were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), Thermogravimetry (TG), AC impedance spectroscopy and ionic transport measurements. XRD and FTIR studies confirm the amorphous nature of the polymer electrolyte and the complexation of salt with polymer. The thermal behavior of polymer electrolytes has been studied from DSC and TG. The highest conductivity obtained using AC impedance spectroscopy is 1.03×10−5 Scm−1 at 303 K for 70 wt%PVAc:30 wt%PMMA:0.8 wt% of LiCl polymer-salt complex. The plasticizer ethylene carbonate (EC) and nanofiller titania (TiO2) were added to the optimized high conducting blend polymer electrolyte. An enhancement in conductivity by one order of magnitude was observed for the plasticized 70 wt%PVAc-30 wt%PMMA-0.8 wt% LiCl polymer electrolyte at ambient temperature. The ionic conductivity value obtained using AC impedance spectroscopy for the plasticized 70 wt%PVAc-30 wt%PMMA-0.8 wt% LiCl polymer electrolyte was 1.03×10−4 Scm−1. The highest conductivity obtained for 70 wt%PVAc-30 wt%PMMA-0.8% LiCl-6 mg TiO2 was 4.45×10−4 Scm−1. Dielectric properties of polymer films are studied and discussed. The electrochemical stability of 1.69 V and 2.69 V was obtained for 70 wt%PVAc-30 wt%PMMA-0.8% LiCl and 70 wt%PVAc-30 wt%PMMA-0.8% LiCl-6 mg TiO2 polymer electrolytes, respectively, using linear sweep voltammetry. The value of Li+ ion transference number was estimated by the DC polarization method and was found to be 0.99 for the highest conducting 70 wt%PVAc-30 wt%PMMA-0.8 wt% LiCl-6 mg TiO2 nanocomposite polymer electrolyte.

A nanospherical ordered mesoporous Lewis acid polymer for the direct glycosylation of unprotected and unactivated sugars in water

The design of robust solid catalysts which can selectively synthesize highly functionalized carbohydrate derivatives from unprotected and unactivated simple sugars in water is an outstanding challenge. Herein we describe the preparation of a novel nanospherical ordered mesoporous Lewis acid polymer (Sc(OTf)2-NSMP) by functionalizing the mesoporous phenol-formaldehyde polymer framework with scandium triflate groups. In the C-glycosylation reaction between D-glucose and dimedone with the Sc(OTf)2-NSMP catalyst, the conversion was 99% and the yield of xanthone-C-glucoside reached 92% after 2 days, which exceeded the previous best results. It was shown that other xanthone glycosides can be obtained from various sugars with moderate to good yields. Furthermore, the catalyst can be easily recovered and reused at least seven times without loss of catalytic activity.