Solid polymer electrolyte based on pluronic P123 triblock copolymer-siloxane organic-inorganic hybrid

A novel organic-inorganic hybrid electrolyte based on poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (Pluronic P123) complexed with LiClO₄ via the co-condensation of an epoxy trialkoxysilane and tetraethylorthosilicate was prepared. Characterization was madeby a variety of techniques including powder X-ray diffraction, AC impedance, differential scanning cabrimetry (DSC), thermogravimetric analysis (TGA), and multinuclear solid state NMR measurements. The hybrid with [O]/[Li] = 16 exhibited a mesophase with a certain degree of ordering, which arose by the self-assembly of P123 with the silica network. The P123 triblock copolymer acts as a structure-directing surfactant to organize with silica networks and as a polymer matrix to dissolve alkali lithium salts as well. The DSC results indicated the formation of transient crosslinking between Li⁺ ions and the ether oxygens of the EO and PO segments, resulting in an increase the T_g with in creasing salt concentrations. Variable temperature ⁷Li-{¹H} MAS NMR spectra revealed the presence of two different local environments for lithium cations, probably due to the lithium cat ions in the polymer-rich domain and in the silica-rich do main, re spectively. A combination of XRD and conductivity results suggests that the drastically enhanced conductivity for the ordered hybrid electrolyte is closely related to the formation of mesophase, which may pro vide unique Li⁺ conducting pathways.