Composite Electrolytes for Lithium Batteries:  Ionic Liquids in APTES Cross-Linked Polymers

Abstract

Solvent free polymer electrolytes were made consisting of Li + and pyrrolidinium salts of trifluoromethanesulfonimide added to a series of hyperbranched poly(ethylene oxide)s (PEO). The polymers were connected by triazine linkages and crosslinked by a sol-gel process to provide mechanical strength. The connecting PEO groups were varied to help understand the effects of polymer structure on electrolyte conductivity in the presence of ionic liquids. Polymers were also made that contain poly(dimethylsiloxane) groups, which provide increased flexibility without interacting with lithium ions. When large amounts of ionic liquid are added, there is little dependence of conductivity on the polymer structure. However, when smaller amounts of ionic liquid are added, the inherent conductivity of the polymer becomes a factor. These electrolytes are more conductive than those made with high molecular weight PEO imbibed with ionic liquids at ambient temperatures, due to the amorphous nature of the polymer.

Application of quaternary polymer electrolyte based on ionic liquid in LiFePO4/Li, Li4Ti5O12/Li and LiFePO4/Li4Ti5O12 batteries

“…The increased interest in polymerized ionic liquids (PILs) is due to their comparatively high ionic conductivity and good mechanical strength [21,22]. Various polymers such as PEO [23][24][25][26][27][28][29][30][31], homo-and co-polymers of poly(vinylidene fluoride) (PVdF) [32][33][34][35][36][37] and poly(ethylene glycol) dimethyl ether [38] have been used to prepare polymer electrolytes with ionic liquids and have been studied over the last few years. Among them PVdF and its copolimers are important due to their high strength and good stability [39][40][41].…”

Pyrrolidinium-based polymeric ionic liquids as mechanically and electrochemically stable polymer electrolytes

“…Two main strategies have been pursued by the scientific community in an attempt to translate the benefits of ILs to polymer electrolytes for lithium batteries. The first strategy involves designing polymer electrolytes composed of conventional polymer matrices such as poly(ethylene oxide) derivatives and ionic liquids [5,7,[9][10][11]. The second strategy consists of synthesizing new functional polymers by polymerization of ionic liquid monomers and using them as matrices for polymer electrolytes [12][13][14][15].…”

Tuning the Properties of Functional Pyrrolidinium Polymers by (Co)polymerization of Diallyldimethylammonium Ionic Liquids

“…[9] Pyrrolidinium ionic liquids have emerged as one of the most promising ionic liquids for application in lithium batteries because of their superior electrochemical stability with respect to classic imidazolium ionic liquids. [10] Very recently, we reported the preparation of mechanically and electrochemically stable polymer electrolytes based in poly(diallyldimethylammonium bis(trifluoromethanesulfonyl)imide) blended with the corresponding pyrrolidi- The synthesis and polymerization of novel diallyldimethylammonium ionic liquid monomers is described. A free-radical polymerization follows a ring-closing cyclopolymerization mechanism similar to the one observed previously for diallyldimethylammonium halides that leads to pyrrolidinium functional polymers.…”