NMR Study on LiBr·H₂O-Al₂O₃ Composite Solid Electrolyte

Abstract

Enhancement of ionic conductivity in the LiBr·H₂O-Al₂O₃ composite solid electrolyte was studied by means of the ⁷Li spin-lattice relaxation time T₁. In α-LiBr·H₂O, T₁ was determined by the Li diffusion with an activation energy of 52kJ mol^-1. In the composite solid electrolyte, two values of T₁ were observed at each temperature. One of them was attributed to LiBr·H₂O, because it had the same value as T₁ of LiBr·H₂O, while the other had a very low activation energy of 18kJ mol^-1. This is the first time that the presence of a highly conductive phase in the composite solid electrolyte has been confirmed experimentally. Magnetization showed that the volumes of these two phases were about equal. The thickness of the highly conductive layer on an alumina particle was estimated to be 0.07∼0.2μm.