Polymeric Backbone Eutectogels as a New Generation of Hybrid Solid-State Electrolytes

Abstract

This work introduces the polymeric eutectogel (P-ETG) solid composite electrolytes (SCEs) developed from the encapsulation of a liquid deep eutectic solvent (DES) electrolyte within a solid amide-based polymer backbone. Compared to their silica-based eutectogel counterparts, the P-ETGs can be efficiently processed by means of UV curing from liquid precursors and possess superior mechanical flexibility. The P-ETGs are characterized by a good electrochemical stability (up to 4.5 V vs Li) and high ionic conductivity up to 0.78 mS cm–1. The potentiality of P-ETG for application in Li/Li-ion batteries is substantiated by stable cycling results of Li/P-ETG/LiFePO4 cells over 100 cycles at C/5 to 1C rates. The fire-hazards analysis reveals the improved safety of P-ETGs in contrast to the conventional liquid electrolytes (1 M LiPF6 in EC/DEC).

Low‐Molecular‐Weight Supramolecular‐Polymer Double‐Network Eutectogels for Self‐Adhesive and Bidirectional Sensors

“…[ 1 ] Owing to the intrinsic characteristics of high conductivity, low vapor pressure, high thermostability, and low cost of DESs, [ 2 ] eutectogels are alternative flexible ionic conductors to temperature intolerant hydrogels and expensive ionic liquid gels, exhibiting potential applications in energy, (bio)electronics and environmental sciences. [ 1,3 ] Despite the recent developments, current polymer eutectogels, such as frequently used polyacrylamide and polyacrylate eutectogels, experience several issues, for example, lack of self‐recovery and self‐healing, limited stretchability and conductivity, and insufficient surface‐adaptive adhesion. [ 4 ] On the other hand, low‐molecular‐weight supramolecule eutectogels, which are self‐assembled by small molecules via reversible noncovalent interactions, demonstrate excellent self‐healing capabilities and comparable conductivity to neat DESs, however, they exhibit inferior mechanical performance and processability.…”

Deep Eutectic Solvents as Nonflammable Electrolytes for Durable Sodium‐Ion Batteries

“…Pure NMA has a flash point of 108 °C and its low vapor pressure prohibits the formation of combustible vapor, which explains the difficult ignition of 1.52 and 3.42 m NaTFSI/NMA. [ 42 ] The further decrease in flammability of 5.86 m NaTFSI/NMA can be explained by the strong ionic interactions, which further decrease the vapor pressure. The flammability of electrolytes can be classified using the self‐extinguishing time (SET), which expresses the flame's lifetime normalized to the sample mass.…”

Deep eutectics and analogues as electrolytes in batteries

“…232 LiTFSI-based DESs were for instance incorporated into polymer backbones, 233,234 or silica matrices, 235 obtaining electrolytes with enhanced conductivity and good electrochemical stability, some showing good performances when applied in Li/Li-ion batteries. 234,235 The gelation of DES electrolytes by functional polymers was also used as a strategy to get non-flammable quasi-solid electrolytes that not only presented improved ionic conductivity and electrochemical stability, but also possessed superior mechanical strength and flexibility, as well as enhanced safety because they avoided leakage risks of toxic or corrosive liquids. 142,236,237 Tested in LIBs, some of these gel electrolytes showed a high potential for safe, robust and high performance devices.…”