The cubic garnet-phase of Li7La3Zr2O12 is one of the most promising new electrolytes for use in an all-solid-state battery. We are proposing a total scattering experiment on samples concentrated in Li-7 isotope, with results to be analysed by the Reverse Monte Carlo method, to give unique information on the distribution of lithium positions and diffusion pathways. We have recent obtained a set of complementary x-ray total scattering data which will be combined with the proposed neutron scattering data in the analysis.