Novel electrospun polymer electrolytes incorporated with Keggin-type hetero polyoxometalate fillers as solvent-free electrolytes for lithium ion batteries

In this study, solvent-free nanofibrous electrolytes were fabricated through an electrospinning method. Polyethylene oxide (PEO), lithium perchlorate and ethylene carbonate were used as polymer matrix, salt and plasticizer respectively in the electrolyte structures. Keggin-type hetero polyoxometalate (Cu-POM@Ru-rGO, Ni-POM@Ru-rGO and Co-POM@Ru-rGO (POM, polyoxometalate; rGO, reduced graphene oxide)) nanoparticles were synthesized and inserted into the PEO-based nanofibrous electrolytes. TEM and SEM analyses were carried out for further evaluation of the synthesized filler structures and the electrospun nanofibre morphologies. The fractions of free ions and crystalline phases of the as-spun electrolytes were estimated by obtaining Fourier transform infrared and XRD spectra, respectively. The results showed a significant improvement in the ionic conductivity of the nanofibrous electrolytes by increasing filler concentrations. The highest ionic conductivity of 0.28 mS cm(-1) was obtained by the introduction of 0.49 wt% Co-POM@Ru-rGO into the electrospun electrolyte at ambient temperature. Compared with solution-cast polymeric electrolytes, the electrospun electrolytes present superior ionic conductivity. Moreover, the cycle stability of the as-spun electrolytes was clearly improved by the addition of fillers. Furthermore, the mechanical strength was enhanced with the insertion of 0.07 wt% fillers to the electrospun electrolytes. The results implied that the prepared nanofibres are good candidates as solvent-free electrolytes for lithium ion batteries. (c) 2020 Society of Chemical Industry