Studies on a nanocomposite solid polymer electrolyte with hydrotalcite as a filler

Abstract

We have prepared a new nanocomposite polymer electrolyte using nanoparticles of hydrotalcite, an anionic clay, as the filler. Hydrotalcite has the chemical composition [M 1 − x 2+ M x 3+( OH) 2] x+ [(A x/ n n −·mH 2O] where M 2+ is a divalent cation (e.g. Mg 2+, Ni 2+, Co 2+,etc.) and M 3+ is a trivalent cation (e.g. Al 3+, Fe 3+, Cr 3+, etc.). A n− is an anion intercalated between the positively charged double hydroxide layers. The nanoparticles of [Mg 0.67Al 0.33(OH) 2] [(CO 3) 0.17·mH 2O] were prepared by the co-precipitation method (average particle size as observed by TEM ∼ 50 nm) and were doped into poly(ethylene glycol) PEG (m.w. 2000) complexed with LiClO 4. Samples with different wt.% of hydrotalcite were prepared and characterized using XRD, DSC, TGA, impedance spectroscopy and NMR. Ionic conductivity for the pristine sample, ∼ 7.3 × 10 − 7 S cm − 1 , was enhanced to a maximum of =1.1 × 10 − 5 S cm − 1 for 3.6 wt.% nanoparticle doped sample. We propose that the enhancement of ionic conductivity is caused by percolation effects of the high conductivity paths provided by interfaces between the nanoparticles and the polymer electrolyte.