Polarised QENS for determining the Haven Ratio in Lithium Solid State Electrolytes

All solid state batteries offer a potential route to address the poor range, slow charging, and safety issues associated with current liquid electrolyte batteries in cars, by utilizing metal anodes. However, reaching commercial SSBs is a multi-faceted problem with many limitations; one of which is the reduction in ionic conductivities as you go from liquid to solid electrolytes. Understanding the specific role of the prefactors that drive diffusion is vital for creating solid electrolytes with faster dynamics. One such prefactor is the Haven ratio, the ratio between ion and charge drive diffusion.
Here we will attempt to experimentally determine the microscopic Haven ratio by separating the coherent and incoherent dynamical structure factors of Li6PS5Cl (lithium-7 enriched). The incoherent scattering will represent single ion diffusion through the bulk structure, whilst coherent scattering will be presented if caterpillar diffusion is present. By isolating these two types of diffusive mechanisms, one will be able to accurately determine whether there is significantly more caterpillar diffusion than predicted by DFT calculations and whether the macroscopic Haven ratio is accurate. From this understanding, novel solid-state electrolytes for the electric vehicle market that optimize the Haven ratio, by maximizing the amount of charge-driven diffusion, will be synthesized.