The feasibility of spatially resolved Raman spectroscopy probing diffusion multiples as a high-throughput method to study phase transformations in Li-ion conductors is demonstrated. The method is applied to the pseudobinary LiBH 4-LiI system, which shows high Li-ion conductivity in the HT-phase of LiBH4. The vibrational properties measured as a function of composition and temperature corroborate the formation of a solid solution of Li (BH4)1-cIc over nearly the entire phase diagram (0<c0.8±0.2). The results shed light on anharmonic effects responsible for the structural phase transformation in this system. © 2010 American Institute of Physics.