Structure and dynamics in an organic ionic plastic crystal, N-ethyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl) amide, mixed with a sodium salt

Abstract

We present for the first time, the solid state phase behaviour of the organic ionic plastic crystal (OIPC) N-methyl-N-ethyl-pyrrolidinium bis(trifluoromethanesulfonyl)amide, [C2mpyr][NTf2], upon mixing with the sodium salt, Na[NTf2].

A study of phase behavior and conductivity of mixtures of the organic ionic plastic crystal N-methyl-N-methyl-pyrrolidinium dicyanamide with sodium dicyanamide

“…However, an extra peak was observed at 88 ± 1°C in the binary systems containing Na[N(CN) 2 ], and the enthalpy (i.e., area) of this peak increased significantly relative to that of the final melting peak as the Na[N(CN) 2 ] concentration increased, as shown in Table 1. This effect was also seen in mixtures of Na[NTf 2 ] and [C 2 mpyr][NTf 2 ] [41]. As previous studies on Na [41] and Li salt [15,40,42,43] 2 ] binary system, when we examine the shapes of the transitions at 15 and 25 mol% salt, we see "tails" or "shoulders", which are indicative of two separate peak positions.…”

“…This effect was also seen in mixtures of Na[NTf 2 ] and [C 2 mpyr][NTf 2 ] [41]. As previous studies on Na [41] and Li salt [15,40,42,43] 2 ] binary system, when we examine the shapes of the transitions at 15 and 25 mol% salt, we see "tails" or "shoulders", which are indicative of two separate peak positions. This behavior implies that the eutectic composition is around 20 mol% salt, and that the 20 mol% mixture melts at the eutectic temperature, T E .…”

“…Beyond the eutectic composition, slight decreases in enthalpy were observed while a new melting transition (liquidus) associated with a second solid phase appeared. [41]. Of course, the phase diagram is probably much more complex than this, as is highlighted from the NMR data below.…”

Phase Behavior of the [N(C₂H₅)₄][BF₄]-[N(C₃H₇)₄][BF₄] Binary System

“…3,12,[15][16][17] During considerable efforts to increase the ionic conductivity of OIPCs, the method of doping of the salts of target ions into OIPCs has been adopted since it was reported to significantly increase the ionic conductivity up to several orders of magnitude. 5,7,9,[18][19][20][21][22][23] Among these materials, [N-ethyl-N-methylpyrrolidinium][N(SO 2 -CF 3 ) 2 ] was one of the OIPCs to exhibit high ionic conductivity, and doping with Li[N(SO 2 CF 3 ) 2 ] salt to this OIPC was found to result in enhancement in ionic conductivity by twenty times and was very attractive for lithium secondary battery application. 5,19,20 Addition of an inorganic salt to OIPCs has been mainly carried out to introduce mobile ions such as Li + to achieve good ion conduction, whereas mixing two OIPCs is also considered as a method to obtain high ionic conductivity, which typically focuses on the change of their structural and thermal properties.…”

17th International Meeting on Lithium Batteries

“…Maria Forsyth (Deakin University, Australia) presented organic ionic plastic crystals (OIPCs, solidifi ed ionic liquids), which show good electrochemical behaviour. Phosphonium based OIPCs incorporating Na salts show electrochemical properties similar to Li containing analogues (62)(63)(64). However, the presence of multiple phases, high viscosity and high-temperature eutectics remain issues which can be altered by a careful choice of ion combination (65).…”