Solid state NMR investigation of a novel Li ion ceramic electrolyte Li doped BPO_4

Over the last decade lithium ion conducting batteries have emerged as the leading technology in battery materials. Their performance, however, is limited to applications below around 50 deg C by the liquid nature of the electrolytes used. In the quest for a solid state electrolyte for use in high temperature applications the nano-crystalline ceramic lithium doped boron phosphate material was developed. Solid state nuclear magnetic resonance (NMR) has been employed to investigate some of the fundamental properties of this material including ionic mobility, defect structure, sample purity and ionic distribution. The findings of this work show that when synthesised at a reaction temperature above 600 deg C the loss of boron from the structure results in the incorporation of vacancy sites about which the Li ions gather in small clusters. Multiple-pulse multiple-quantum spin counting techniques are employed in an effort to count the number of quadrupolar "7Li nuclei interacting in a cluster though it is ultimately found that this technique is limited. Rotational echo double resonance (REDOR) curves are calculated and compared with experimental data in order to further investigate the dipolar coupling characteristics within the material. (author)Available from British Library Document Supply Centre- DSC:DXN060309 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo