Electrospun Li1.3Al0.3Ti1.7(PO4)3 nanofibers as ion-conducting fillers for polyethylene oxide/poly(vinylidene fluoride) composite solid electrolytes

Polyethylene oxide (PEO)-based composite solid electrolytes containing electrospun lithium aluminum titanium phosphate (LATP) and poly(vinylidene fluoride) (PVDF) nanofibers were fabricated to investigate the influence of LATP filler morphology on ionic conduction. LATP precursor nanofibers with the nominal composition Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 were prepared by electrospinning followed by calcination, whereas PVDF nanofibers were incorporated as a fibrous structural component without heat treatment. TGA/DTG analysis showed multistep removal of residual solvents and precursor-derived organic species, and XRD confirmed crystallization of NASICON-type LATP. A weak AlPO 4 secondary-phase peak was already detectable at 800 °C and became more evident at 900 and 1000 °C; therefore, 700 °C was selected as the calcination temperature. DSC analysis showed a composition-dependent effect of filler morphology on PEO crystallinity; notably, at 25 wt% LATP the nanofiber-containing membrane exhibited a lower PEO crystallinity (17.4%) than the corresponding particle-containing membrane (43.7%). Electrochemical impedance spectroscopy showed that the ionic conductivity varied strongly with LATP filler morphology and composition, reaching 1.19 × 10 −4 S cm −1 at room temperature for the 25 wt% sample, whereas the corresponding particle-filled membrane exhibited 5.15 × 10 −6 S cm −1 . Because LATP and PVDF fractions were varied simultaneously, the conductivity trend is interpreted as a combined compositional, morphological, and interfacial effect rather than as an isolated LATP-content effect.