Modification and characterization of microporous lithosilicates Li-conductors

• Applicant: Professorin Dr. SoHyun Park
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2004 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5439909

The microporous lithosilicate RUB-29 (Cs14Li24[Li18Si72O172]· 14H2O) belongs to a new class of zeolitic materials in which lithium occurs as a network-builder and -modifier, rather than the more usual case where Li is exclusively located in the pores and channels to charge-balance the anionic framework. Preliminary NMR and conductivity measurements suggest the Li+ cations are involved in fast hopping motions inside RUB-29. The framework lithium is partitioned exclusively into the Li2O portion of the framework, therefore, a pronounced increase of defect sites in RUB-29 can be ensured by isomorphic substitution of multi-valent cations for mono-valent Li+. Some examples of the substitution will be carried on here by hydrothermal synthesis to create RUB-29 derivatives as possible Li-battery materials with higher Li conductivity. Structures and Li dynamics of ion-exchanged RUB-29 materials are also under investigation to show effects of extraframework cations on Li motions in RUB-29. The concepts "modulated crystal structures" will be used for joined structure analysis with X-ray and neutron diffraction data to better deal with difficulties in analyzing the superstructure of RUB-29. Li-dynamics of Li+ cations will be determined using quasi-elastic neutron backscattering, impedance, and 6Li MAS NMR spectroscopy.

• DFG Programme: Research Grants