SISGR: Linking Ion Solvation and Lithium Battery Electrolyte Properties

The solvation and phase behavior of the model battery electrolyte salt lithium trifluoromethanesulfonate (LiCF3SO3) in commonly used organic solvents; ethylene carbonate (EC), gamma-butyrolactone (GBL), and propylene carbonate (PC) was explored. Data from differential scanning calorimetry (DSC), Raman spectroscopy, and X-ray diffraction were correlated to provide insight into the solvation states present within a sample mixture. Data from DSC analyses allowed the construction of phase diagrams for each solvent system. Raman spectroscopy enabled the determination of specific solvation states present within a solvent-ÃÂÃÂsalt mixture, and X-ray diffraction data provided exact information concerning the structure of a solvates that could be isolated Thermal analysis of the various solvent-salt mixtures revealed the phase behavior of the model electrolytes was strongly dependent on solvent symmetry. The point groups of the solvents were (in order from high to low symmetry): C2V for EC, CS for GBL, and C1 for PC(R). The low symmetry solvents exhibited a crystallinity gap that increased as solvent symmetry decreased; no gap was observed for EC-LiTf, while a crystallinity gap was observed spanning 0.15 to 0.3 mole fraction for GBL-LiTf, and 0.1 to 0.33 mole fraction for PC(R)-LiTf mixtures. Raman analysis demonstrated the dominance of aggregated species in almost all solvent compositions. The AGG and CIP solvates represent the majority of the species in solutions for the more concentrated mixtures, and only in very dilute compositions does the SSIP solvate exist in significant amounts. Thus, the poor charge transport characteristics of CIP and AGG account for the low conductivity and transport properties of LiTf and explain why is a poor choice as a source of Li+ ions in a Li-ion battery

SISGR: Linking Ion Solvation and Lithium Battery Electrolyte Properties

The solvation and phase behavior of the model battery electrolyte salt lithium trifluoromethanesulfonate (LiCF3SO3) in commonly used organic solvents; ethylene carbonate (EC), gamma-butyrolactone (GBL), and propylene carbonate (PC) was explored. Data from differential scanning calorimetry (DSC), Raman spectroscopy, and X-ray diffraction were correlated to provide insight into the solvation states present within a sample mixture. Data from DSC analyses allowed the construction of phase diagrams for each solvent system. Raman spectroscopy enabled the determination of specific solvation states present within a solvent-ÃÂÃÂsalt mixture, and X-ray diffraction data provided exact information concerning the structure of a solvates that could be isolated Thermal analysis of the various solvent-salt mixtures revealed the phase behavior of the model electrolytes was strongly dependent on solvent symmetry. The point groups of the solvents were (in order from high to low symmetry): C2V for EC, CS for GBL, and C1 for PC(R). The low symmetry solvents exhibited a crystallinity gap that increased as solvent symmetry decreased; no gap was observed for EC-LiTf, while a crystallinity gap was observed spanning 0.15 to 0.3 mole fraction for GBL-LiTf, and 0.1 to 0.33 mole fraction for PC(R)-LiTf mixtures. Raman analysis demonstrated the dominance of aggregated species in almost all solvent compositions. The AGG and CIP solvates represent the majority of the species in solutions for the more concentrated mixtures, and only in very dilute compositions does the SSIP solvate exist in significant amounts. Thus, the poor charge transport characteristics of CIP and AGG account for the low conductivity and transport properties of LiTf and explain why is a poor choice as a source of Li+ ions in a Li-ion battery

Effect of fibre spinning conditions on the electrical properties of cellulose and carbon nanotube composite fibres spun using ionic liquid as a benign solvent

The aim of this study was to develop electrically conductive fibres from cellulose. To achieve this, the effect of fibre extrusion speed and fibre winding speed on the degree of alignment of multiwall carbon nanotubes (MWNTs), as well as the resulting electrical properties of the cellulose/MWNTs composite fibres were systematically studied. 1-Ethyl-3-Methylimidazolium Acetate (EMIMAc) was used as an environmentally benign solvent for dissolution of cellulose as well as for dispersion of MWNTs in the solution dope. To achieve good dispersion of MWNTs in the cellulose solution dope, MWNTs were non-covalently functionalized using carboxymethyl cellulose (CMC). This significantly improved the dispersion of MWNTs in the solution dope. The degree of alignment of MWNTs after both fibre extrusion and winding, was studied using scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The degree of alignment of MWNTs was correlated with the electrical properties. A significant decrease in electrical conductivity accompanied the increase in degree of alignment of MWNTs when fibres were spun with higher extrusion speed. The decrease was also measured when fibres were spun with higher winding speed using a constant extrusion speed. However, the decrease in conductivity due to winding was low relative to fibres spun at highest extrusion speed

Fiber welded EDTA-modified cellulose for remediation of heavy metal ions

Ethylenediaminetetraacetic acid (EDTA) is a well-known metal chelator and an attractive ligand for covalently modifying adsorbents for bioremediation. Cellulose, a naturally occurring biopolymer, has immense potential as an inexpensive, earth abundant, biocompatible scaffold for EDTA-facilitated environmental remediation; however, pretreatment of the material is required to achieve sufficient degrees of chemical modification. In this study, Natural Fiber Welding (NFW) is used to prepare commercial cotton Aida cloth for EDTA functionalization. Following NFW, the cotton scaffold was covalently modified with up to 0.56 mmol of EDTA per gram of adsorbent, a nearly 2.5-fold increase over native material. The welded EDTA-modified substrates were tested qualitatively against cobalt and quantitatively against nickel, reaching equilibrium binding capacities (qe) of up to 46 mg metal per g of adsorbent, on par with capacities reported from past work on EDTA-modified cellulose. In addition, adsorbent material could be regenerated using mild acid treatment with no significant loss in qe. Unlike the controls, the fiber-welded EDTA-Aida did not fray even after 3 chelation cycles, indicating enhanced textile robustness afforded through NFW treatment. Overall, NFW offers a new approach to converting commercially available, sustainable biomaterials into robust adsorbents for environmental remediation

Mesoporous Natural Fiber Welded Cellulose Containing Silver Nanoparticles as a Recyclable Heterogeneous Catalyst

Abstract Silver nanoparticles (AgNPs) are presented within mesoporous natural fiber welded (NFW) cellulose and demonstrated as robust catalysts to reduce 4‐nitrophenol using sodium borohydride. Growing AgNPs this way enables their retention within a nonderivatized, mesoporous, all‐cellulose NFW composite. At an AgNP loading of 1.0 wt%, no leaching is observed during rinsing with polar and nonpolar solvents or any of 12 catalyst cycles and the cloth is easily retrievable and reusable. Comparatively, a 1.0 wt% AgNP loading on non‐NFW cotton thread loses ≈95% of the starting Ag under similar conditions. Only at higher loadings is a very slow leaching observed in the NFW composite (<10% Ag loss). With a turnover frequency of 0.9 h–1 (as compared to 2.2 h–1 for the non‐NFW cotton thread), the catalytic activity suffers only minor impedance from the NFW structure while affording significant promise in future applications for leach‐resistant nonderivatized cotton (e.g., TiO2 or photonic nanomaterials). Finally, it is shown that combustion of AgNPs‐NFW composites creates Ag residues distinct from materials produced via combustion of AgNPs on non‐NFW cotton. While the residues produced comprise Ag and residual carbon, this method is viable for producing metal “sponges” from monometallic and bimetallic NPs on mesoporous cellulose

Accelerated Fabrication of Fiber-Welded Mesoporous Cotton Composites

Natural fiber-welded (NFW) biopolymer composites are rapidly garnering industrial and commercial attention in the textile sector, and a recent disclosure demonstrating the production of mesoporous NFW materials suggests a bright future as sorbents, filters, and nanoparticle scaffolds. A significant roadblock in the mass production of mesoporous NFW composites for research and development is their lengthy preparation time: 24 h of water rinses to remove the ionic liquid (IL) serving as a welding medium and then 72 h of solvent exchanges (polar to nonpolar), followed by oven drying to attain a mesoporous composite. In this work, the rinsing procedure is systematically truncated using the solution conductivity as a yardstick to monitor IL removal. The traditional water immersion rinses are replaced by a flow-through system (i.e., infinite dilution) using a peristaltic pump, reducing the required water rinse time for the maximum removal of IL to 30 min. This procedure also allows for easy in-line monitoring of solution conductivity and reclamation of an expensive welding solvent. Further, the organic solvent exchange is minimized to 10 min per solvent (from 24 h), resulting in a total combined rinse time of 1 h. This process acceleration reduces the overall solvent exposure time from 96 to 1 h, an almost 99% temporal improvement