Size effect of cubic ZrO2 nanoparticles on ionic conductivity of polyethylene oxide-based composite

Abstract

A solvent free solid composite polymer electrolyte (SCPE) film consisting of high molecular mass polyethylene oxide (PEO) with sodium perchlorate (NaClO 4 ) as electrolytic salt and cubic zirconium oxide (ZrO 2 ) nanoparticles as the filler has been prepared by solution casting technique to influence the transport properties. X-ray diffraction and Fourier transform infrared spectroscopy confirm the formation of the SCPE film, whereas atomic force microscopy reveals the presence of a network of interconnected nanoparticles forming uniform surface feature of relatively low roughness. The highest ionic conductivity (r ¼ 6.96 Â 10 À5 S-cm À1 ) for PEO 25 -NaClO 4 with 5 wt. % ZrO 2 nanoparticles of the smallest size 4.5 nm is an order of magnitude higher than the pure PEO 25 -NaClO 4 at room temperature. The conductivity enhancement is due to the creation of additional sites and favorable conduction pathways for ionic transport through Lewis acid-base type interactions between the polar surface groups of the ceramic filler and the electrolyte ionic species.

Composite Polymer Electrolytes: Nanoparticles Affect Structure and Properties

“…The importance of polymer crystallinity in the study of CPEs cannot be overrated. Crystallinity is affected by temperature, amount of lithium salt and nanoparticle changes [26,62,63,64,67,68]. Crystallinity underlies the performance of CPEs such as conductivity and mechanical strength.…”

“…The polymer chain conformation influences the dynamics of the lithium ions coordinated with the polymer backbones [ 69 ] because Li + ions exhibit different binding energies with the different conformers [ 70 ]. The polymer chain conformation can change due to nanoparticle addition as shown by Raman [ 62 ] and FTIR spectroscopy [ 67 , 71 , 72 ]. In the 700–1600 cm −1 Raman spectra of a PEO-sodium montmorillonite system, there are four characteristic regions corresponding to four types of vibration bands: CH 2 rocking vibrations, C–O–C stretching vibrations, CH 2 twisting vibrations and CH 2 bending vibrations [ 62 ].…”

Separators - Technology review: Ceramic based separators for secondary batteries

“…In the case of gel polymer electrolytes, an enhanced ion conductivity in comparison with the separator without ceramic fillers was reported [51]. This finding was assigned to the interaction of the polar surface groups of the gel electrolyte and the ceramic particles, which created additional conduction pathways for the ion transport.…”

“…More than a decade ago, Prosini et al [59] reported the development of a composite separator for lithium-ion batteries that utilized Al 2 O 3 , MgO 2 , and LiAlO 2 ceramic particles as fillers for a PVDF-HFP polymer matrix. Among them, Al 2 O 3 became the most popular filler [50,54,56,59,62,63], but TiO 2 [64], CaCO 3 [58], SiO 2 [14,50,54,63,65] and ZrO 2 [50,51,63] have also been used. In general, besides the mentioned oxides and carbonates, also nitrides or carbides of Si, Al, Zr, Sn, Ce or Y have been suggested [50], such as SiC [63].…”

“…Ceramic particles added to a polymeric binder or polymer electrolyte can be also processed in other ways. The mixture can be applied directly on an electrode by e. g. hot lamination [59], spraying [65] or a solution casting technique [51]. Except for the hot lamination route, a drying step is necessary, which can be followed by curing [65].…”