Highly-fluorous pyrazolide-based lithium salt in PVDF-HFP as solid polymer electrolyte

• Usage of a new, highly fluorous lithium salt in a PVDF-HFP host
• Salt concentration in the polymer-in-salt system up to 80 wt.%
• Determination of fluorophilicity
• Decomposition of LiPFAPB14 is inhibited by PVDF-HFP.
• Fast membrane preparation by an easy solution casting technique

For the first time, the concept of fluorophilicity fi is adapted to the development of a novel solid polymer electrolyte (SPE) by computationally evaluating a new class of lithium salts, the perfluoroalkylated pyrazolides. An SPE consisting solely of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) and different concentrations of highly-fluorous lithium [5-(perfluorobutyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] trifluoroborate (LiPFAPB14) is reported. Membranes with a salt concentration up to 80 wt.% are prepared and are investigated by 3D laser scanning confocal microscopy, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) concerning the correlation between the LiPFAPB14 salt concentrations with the miscibility in PVDF-HFP. Membrane performances as SPE are evaluated by impedance spectroscopy revealing ionic conductivities of 1.4 × 10− 4 S cm− 1 at 90 °C with 80 wt.% LiPFAPB14.