Highly Conducting Bombyx mori Silk Fibroin-Based Electrolytes Incorporating Glycerol, Dimethyl Sulfoxide and [Bmim]PF6

authors	Fernandes, TCD; Rodrigues, HMR; Paz, FAA; Sousa, JFM; Valente, AJM; Silva, MM; Bermudez, VD; Pereira, RFP
nationality	International
journal	JOURNAL OF THE ELECTROCHEMICAL SOCIETY
keywords	IONIC-LIQUID; MECHANICAL-PROPERTIES; SCAFFOLDS; FILMS; HEXAFLUOROPHOSPHATE; FABRICATION; CHALLENGES; BATTERIES; MEMBRANES; FIBERS
abstract	Green, transparent and flexible electrolyte films composed of a Bombyx mori silk fibroin (SF) host biopolymer doped with glycerol (G), dimethyl sulfoxide (DMSO, D) and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) ionic liquid (IL), were synthesized. The materials were represented by the notation SF@GD@ILx (x = 15, 20 and 30 is the mass ratio of SF/[Bmim]PF6 in %). SF@, SF@G, SF@D and SF@GD samples were also prepared. DMSO was found to play a dual-role, acting as solvent of [Bmim]PF6, and enhancing ionic conductivity. DMSO, alone or combined with [Bmim]PF6, led to the increase of the mean roughness and induced the formation of more ordered Silk II conformations (beta-sheets). No structural modifications were detected in the SF@GD@ILx samples upon increasing the temperature up to 100 degrees C. The highest ionic conductivity was exhibited by the IL-rich sample SF@GD@IL30 (1.07 and 4.61 mS cm(-1), at 22 and 100 degrees C, respectively). In the [Bmim]PF6-doped electrolytes free and coordinated PF6- ions coexist. The weight losses occurring below 200 degrees C involved essentially the release of adsorbed water and DMSO. The suitable mechanical properties, high ionic conductivity and good electrochemical stability suggest that these electrolytes are attractive candidates for application in electrochemical devices. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
publisher	ELECTROCHEMICAL SOC INC
issn	0013-4651
isbn	1945-7111
year published	2020
volume	167
issue	7
digital object identifier (doi)	10.1149/1945-7111/ab8313
web of science category	Electrochemistry; Materials Science, Coatings & Films
subject category	Electrochemistry; Materials Science
unique article identifier	WOS:000524001500001