Physicochemical properties of N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide for sodium metal battery applications.

The physicochemical properties of a range of NaNTf2 (or NaTFSI) salt concentrations in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (or C3mpyrFSI) ionic liquid were investigated by DSC, conductivity, cyclic voltammetry and diffusivity studies. Cyclic voltammetry indicated a stable sodium plating behavior with a current of 5 mA cm(-2) at 25 °C to 20 mA cm(-2) at 100 °C, along with high reversibility identifying this electrolyte as a possible candidate for sodium-ion or sodium metal battery applications. (23)Na NMR chemical shifts and spectral linewidths (FWHM) indicate a complex coordination of the Na(+) ion which is dependent on both temperature and salt concentration with an apparently stronger coordination to the NTf2 anion upon increasing the NaNTf2 concentration. Temperature dependent PFG-NMR diffusion measurements show that both FSI and NTf2 have a comparable behaviour although the smaller FSI anion is more diffusive.

Modular synthesis of linear Bis- and Tris-monodentate fused [6]Polynorbornane-Based Ligands and their assembly into coordination cages

A modular approach has been developed for the synthesis of rigid linear di- and tritopic ligands based on a fused [6]polynorbornane scaffold. The design provides up to three sites for installing functionality, including both "ends" and a "central" position with the advantage that each region can be independently addressed during synthesis. To illustrate the utility of the approach, both pyridyl and picolyl units were incorporated to provide six new ligands, with centers and ends either matched or mismatched. Indeed, both [M2 L4 ] cages with endohedral functionality and [M3 L4 ] complexes were cleanly produced from these ligands with assembled structures confirmed by using (1) H NMR spectroscopy, HRMS, and molecular modelling.

Physical properties of high Li-ion content N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide based ionic liquid electrolytes

Electrolytes based on bis(fluorosulfonyl)imide (FSI) with a range of LiFSI salt concentrations were characterized using physical property measurements, as well as NMR, FT-IR and Raman spectroscopy. Different from the behavior at lower concentrations, the FSI electrolyte containing 1 : 1 salt to IL mole ratio showed less deviation from the KCl line in the Walden plot, suggesting greater ionic dissociation. Diffusion measurements show higher mobility of lithium ions compared to the other ions, which suggests that the partial conductivity of Li(+) is higher at this higher composition. Changes in the FT-IR and Raman peaks indicate that the cis-FSI conformation is preferred with increasing Li salt concentration.