13C CP/MAS and 7Li NMR study of lithium perchlorate/poly(ethylene oxide)

Abstract

To study compositional dependent conductivity of Li+-ions in lithium perchlorate/poly(ethylene oxide) (LiClO4/PEO) electrolytes, mobility of the Li+-ions and morphology of the electrolytes are investigated by examining the spin-lattice relaxation time (T1) of 7Li and by high-resolution solid-state 13C NMR methods. It is shown that the amount of the mobile Li+-ion estimated from the shorter 7Li-T1 component is not directly compared with the reported conductivity. The high-resolution solid-state 13C NMR spectra show that there exists five different CH2 carbons in the LiClO4/PEO electrolytes. The five peaks are assigned to (1) the crystalline phase of pure PEO, (2) the amorphous phase of PEO with the Li+-ions, and three complex phases of the following ratio of (3) PEO:Li+ = 3:1, (4) x:1(3