Ternary polymer electrolytes incorporating pyrrolidinium-imide ionic liquids

Abstract

Herein is reported the performance of ternary polymer electrolytes incorporating ionic liquids, showing higher ionic conductivity over a wide temperature range than binary polymer-salt systems, while guaranteeing higher safety compared to liquid, organic electrolytes or gel electrolytes. In particular, the electrochemical performance and the interactions between poly(ethylene oxide) (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and several pyrrolidinium-based ionic liquids is comparatively investigated. Eight different polymer electrolytes were produced to test the ionic conductivity and longtime (more than 1400 hours) cycling stability in symmetrical lithium cells. Thermal analysis was used to investigate the thermal stability and degree of crystallinity. Six of the eight investigated samples are found fully amorphous at room temperature. In general, the properties of the polymer electrolytes are influenced by both Ionic liquid ions. The ether function in the side chain of the pyrrolidinium increases the ionic conductivity but, in some cases, lowers the thermal and electrochemical stability.

Ionic‐Liquid‐Based Polymer Electrolytes for Battery Applications

“…[58] It was found that the replacement of Pyr 14 with Pyr 12O1 slightly increases the ionic conductivity while all other properties were almost constant for samples with TFSI, FSI, BETI, and IM 14 anions.M ixtures incorporating BETI and IM 14 showed, however, higher overpotential upon lithium plating/stripping,most likely aresult of the larger size of the anion. [58] It was found that the replacement of Pyr 14 with Pyr 12O1 slightly increases the ionic conductivity while all other properties were almost constant for samples with TFSI, FSI, BETI, and IM 14 anions.M ixtures incorporating BETI and IM 14 showed, however, higher overpotential upon lithium plating/stripping,most likely aresult of the larger size of the anion.…”

“…[58,61] The performance of the ternary polymer electrolytes is correlated to the ionic liquid used in terms of ionic conductivity,a nd electrochemical and thermal stabilities.F or example, Pyr 14 TFSI shows aw ide ESW and high ionic conductivity, significantly improving the performance of apolymer electrolyte when incorporated in it. It was shown that the addition of several ionic liquids can lead to completely amorphous polymer electrolytes if the ratio between the three components is chosen carefully.…”

Novel Ternary Polymer Electrolytes Based on Poly(lactic acid) from Sustainable Sources

“…If other salts, including ionic liquids, are added to the polymer matrix, this is here referred to as ternary solid polymer electrolyte (SPE). In the case of ionic liquids, which are salts molten below 100 °C, it was shown that a very efficient plasticization can be achieved while high thermal and electrochemical stability are maintained . This is especially true for pyrrolidinium‐based ionic liquids with fluorinated anions like TFSI, which are poorly flammable and therefore match the safety requirements of batteries very well …”

Ionic Liquid-Based Polymer Electrolytes via Surfactant-Assisted Polymerization at the Plasma–Liquid Interface

“…[6][7][8] For the development of new generation solid electrolytes, ionic liquids (ILs), which offer efficient ion conduction, negligible vapour pressure, and a large thermal and electrochemical stability window, have been incorporated into a mechanical polymer matrix to form solid-state IL-incorporated gel polymer electrolytes (ILGPEs). 4,[9][10][11][12] Depending on the method of preparation, IL-based polymer electrolytes can be classified into three categories including doping of polymer with ILs, in situ polymerization or crosslinking of the monomer in ILs, and synthesis of polymeric ionic liquids (PILs). 13,14 In the two former approaches, ILs are incorporated into a conventional polymer matrix to form an IL-based polymer gel electrolyte (ILPGE).…”