Abstract:
Lithium ion batteries are the main power source for many technologies used in our day to day lives. Improving battery efficiency and safety is of major importance for next generation batteries. The transition from organic battery electrolytes to solid-state materials could resolve some of the safety issues currently plaguing lithium ion batteries. Lithium containing garnet oxides have been suggested as a potential candidate for next generation battery electrolytes due to their electrochemical potential and greater operational stability. Interest in lithium containing garnet oxides as solid-state electrolytes has been increasing over the last decade and a half. The investigation of a new vanadium doped lithium containing garnet oxide and further exploration of structural analysis of tantalum doped garnet oxides was the aim of this project. No successful doping was achieved with the proposed material of Li6.75La3Zr1.75V0.25O12 with Li7La3Zr2O12 and vanadium oxides forming instead. Standard laboratory X-ray powder diffraction, synchrotron sourced X-ray powder diffraction and neutron powder diffraction were all utilized in further exploring the garnet materials of Li7-xLa3Zr2-xTaxO12 (x = 0 – 1). Powder diffraction data sets were processed by Rietveld refinements in determination of the phases present in each analysis. The results of room temperature X-ray, synchrotron and neutron powder diffractions showed little variation of lithium occupancies in tetrahedral and octahedral sites. High temperature neutron powder diffraction revealed a transition in lithium occupancy from tetrahedral to octahedral sites within the garnet with increased temperature. The results from this work indicates more work is required to find a possible synthesis route for the incorporation of vanadium into lithium containing garnet oxides. Further high temperature analysis should be conducted on lithium containing garnet oxide systems as these materials could be ideal for industrial level batteries which operate at temperatures higher then room temperature.