Thermal, structural and dynamic properties of ionic liquids and organic ionic plastic crystals with a small ether-functionalised cation

Abstract

Organic ionic plastic crystals (OIPCs) and ionic liquids (ILs) are promising safer electrolytes for energy storage applications. While ether-functionality in ILs is well known to impart beneficial properties such as...

Structure and interactions of novel ether-functionalised morpholinium and piperidinium ionic liquids with lithium salts

“…Liquid-state 1 H, 13 C and 19 F NMR spectra were collected on a 9.4 T Bruker Avance III instrument. Mass spectroscopy was performed on an Agilent 1200 series HPLC system.…”

“…The DW values (Table S6, ESI †) increase with temperature, indicating ion pairing as temperature increases, and lie between 0.15-0.27 over the temperature range analysed, with the general trend from most dissociated to least dissociated (i.e. lowest to highest DW values) in the order 13,62 Upon addition of Li-salt the DW values increase to 0.21-0.32 due to Li + interacting with anions that form ion pairs and aggregates. As the temperature increases, DW increases more for the TFSI-based electrolytes, indicating a higher degree of ion association or Li + aggregates forming at higher temperatures than for FSI-based electrolytes.…”

“…[9][10][11][12] For example, at 30 1C, the viscosity and ionic conductivity of the neat IL (without any lithium salt) 1-methoxymethyl-1,1,1-trimethylammonium TFSI [N 111,1O1 ] [TFSI] is 44 mPa s and 4.8 mS cm À1 , compared to 63 mPa s and 3.5 mS cm À1 for the alkyl equivalent 1-propyl-1,1,1-trimethylammonium TFSI [N 1113 ][TFSI]. 13,14 In another study, the viscosity and ionic conductivity of (N-(2-methoxyethoxy)methyl)-N-methylpiperidinium TFSI [C (1O2O1) mpip][TFSI] at 30 1C is 69 mPa s and 2.3 mS cm À1 respectively, compared to 132 mPa s and 0.8 mS cm À1 for N-hexyl-N-methylpiperidinium TFSI [C 6 mpip][TFSI]. 15 For lithium batteries, IL electrolytes are prepared by dissolving the corresponding lithium salt (e.g.…”

“…The methoxymethyl chain has been less explored in comparison to longer ether-functionalised chains but has previously been employed on cations such as N-methoxymethyl-N-methylpyrrolidinium [C 1O1 mpyr] + and 1-methoxymethyl-1,1,1-trimethylammonium [N 111,1O1 ] + to demonstrate the promising benefits of the chain. 13,22 [FSI] at 25 1C is 31 mPa s, lower than most ILs, and 0.32 kg mol À1 LiFSI in [C 1O1 mpyr][FSI] has been used to demonstrate stable lithium plating and stripping with a higher current density than alkyl ILs. 23 [C 1O1 mpip][TFSI] has previously been synthesised at 27% yield, and an improved synthetic method is reported here.…”

“…13 C NMR (DMSOd 6 , 100 MHz): d 119 47. (CF 3 , J CF = 320.07 Hz), 91.63 (NCH 2 O), 60.93 (OCH 3 ), 56.43 (CH 2 CH 2 N), 44.12 (NCH 3 ), 20.85 (CH 2 CH 2 CH 2 N), 18.83 (CH 2 CH 2 N) ppm.…”