Effect of Oligo(ethyleneoxy)cyclotriphosphazenes, Tetraglyme, and Other Small Molecules on the Ionic Conductivity of the Poly[bis(methoxyethoxyethoxy)phosphazene] (MEEP)/Lithium Triflate System

Abstract

Four small molecule cyclotriphosphazenes bearing linear and branched ethyleneoxy units have been synthesized as ion transport assistance (ITA) species to improve the ionic conductivity of poly-[bis(methoxyethoxyethoxy)phosphazene] (MEEP)-lithium triflate systems. The cyclotriphosphazenes were characterized by 31 P, 1 H, and 13 C nuclear magnetic resonance spectroscopy and infrared spectroscopy. MEEP was complexed with lithium triflate and combined with different amounts of each of the ITA molecules. Room temperature conductivity measurements and differential scanning calorimetry experiments were carried out on each of these mixtures. The effect of concentration of the ITA molecules and salt on the ionic conductivity of MEEP is reported. The general trend observed is an increased conductivity with increasing ITA molecule concentration. The effect of branching in the ITA molecule on the ionic conductivity was studied by comparing influence of branched versus linear side groups. Differential scanning calorimetry data indicate that these small molecules play a role in ionic cross-linking. The influence of high dielectric solvents on the ionic conductivity of MEEP/LiSO3CF3 systems was also studied. These solvents generated higher conductivities at the same concentration than did the cyclotriphosphazene ITA species.

Lithium-based ionic liquids as novel lubricant additives for multiply alkylated cyclopentanes (MACs)

“…1. The compounds, tri(methoxyethoxyethoxyethoxy)triazine (C 3 N 3 (OR) 3 ) and hexa(methoxyethoxyethoxyethoxy)cyclotriphosphazene (P 3 N 3 (OR) 6 ), were synthesized according to the method described in the literature [14]. Chlorotriazine (C 3 N 3 Cl 3 ) and hexachlorocyclotriphosphazene (P 3 N 3 Cl 6 ) were purchased from Alfa Aesar.…”

Methoxyethoxyethoxyphosphazenes as ionic conductive fire retardant additives for lithium battery systems

“…It was also reported that these polymers have a high onset temperature of thermal degradation (235 • C) together with a modest heat release capacity [23]. Moreover, small molecule cyclic phosphazenes with the same ethyleneoxy side groups have been used either as stand-alone electrolytes or as plasticizers for gel electrolytes, and they are known to function well as solvents and as additives that increase the ionic conductivity of the base macromolecular electrolyte [24,25] (Fig. 2).…”

Silicon-Containing Carbonates—Synthesis, Characterization, and Additive Effects for Silicon-Based Polymer Electrolytes

“…Over the past three decades, ion-conducting polymers have been investigated as promising and safe alternatives to the commercially available electrolytes currently used in lithium batteries [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The initial discoveries that polymer complexes could be used as either liquid [1] or solid [2] ionic conductors has led to the development of a wide range of polymer-based electrolytes.…”

“…However, PEO is crystalline at room temperature and can be electrochemically unstable. Therefore, efforts have focused on the combination of PEO with amorphous polymers such as polyphosphazenes [3][4][5][6][7][8] and polysiloxanes [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] via copolymerization reactions.…”

“…Although significant research has concentrated on the development of polysiloxane-PEO copolymer structures, alternative polymer electrolytes structures have also been investigated [3][4][5][6][7][8][27][28][29]. For example, Wnek and coworkers [27] introduced carbonate groups onto the polysiloxane backbone in order to study them as potential polymer electrolytes.…”