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

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).