Dual‐Supporter and Dual‐Salt Strategy for Solid Polymer Electrolyte with High Ionic Conductivity and Elastic Toughness

Abstract In recent years, ionic liquid (IL)‐based solid polymer electrolytes (SPEs) have attracted much attention as conducting or capacitive materials for stretchable electronics. To fabricate fast and mechanically robust electronic devices, the high ionic conductivity and high elastic toughness of the SPE are essential. However, it has been challenging to achieve both high ionic conductivity and high elastic toughness simultaneously because high ionic conductivity generally requires low crystallinity of the polymer chains. Herein, a facile strategy for fabricating highly conductive, mechanically robust, and thermally stable SPE is demonstrated. A glass fiber mesh and La 0.57 Li 0.29 TiO 3 particles as dual‐supporters are introduced, and 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) and bis(trifluoromethylsulfonyl)amine lithium salt (LiTFSI) (having the same anion) as the dual salt in the polymer electrolyte is introduced. Consequently, the SPE exhibits a superior ionic conductivity of 2.4 × 10 −2 S cm −1 at room temperature and an outstanding elastic toughness of ≈170.3 kJ m −2 . Finally, the dual‐salt/dual‐supporter SPE is successfully applied to high‐performance organic electrolyte‐gated transistors as gate dielectric materials and highly sensitive capacitive pressure sensors as force‐sensitive dielectric layers.