Highly conductive and mechanically robust nanocomposite polymer electrolytes for solid-state electrochemical thin-film devices

Abstract

Abstract Ionic liquid-based polymer electrolyte composites (PECs) with high mechanical strength and ionic conductivity were fabricated by using a semicrystalline homopolymer network. Morphological, mechanical, and electrical properties of semicrystalline homopolymer-based PECs were investigated over the composition range of 10–50 polymer wt%. The PECs consisted of poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]). The amorphous PVDF chains were solvated by the liquid electrolyte and interconnected the phase-separated PVDF crystalline-domains, acting as physical crosslinks. The ionic conductivity and specific capacitance of the homopolymer PECs were found to be very high, ranging from 0.4 to 4.9 mS/cm and from 2.6 to 9.1 μF/cm2, respectively. The elastic moduli of the PECs that range from 4 to 38 MPa were also greater than those of PECs prepared by using other polymeric networks. These PECs were successfully applied as electrolyte membranes in electrical double layer supercapacitors and as high-capacitance gate insulators in electrochemical thin-film transistors. These results provide detailed systematic data for fabricating high-performance solid polymer electrolytes for electrochemical thin-film devices.