Local Structure in a new Class of Metastable Solid Li-ion Electrolytes

All-solid-state batteries based on solid electrolytes (SEs) are promising candidates for safe and high energy density Li-ion batteries. Sulphide-based electroytes proved to be exceptionally good ionic conductors, superior to many commonly used liquid electrolytes. However, the main drawback of these sulphide SEs is their poor chemical stability, especially towards lithium metal. We have synthesised a new metastable SE class that would not decompose in contact with lithium metal anodes. Nuclear magnetic resonance (NMR) and in-house powder x-ray diffraction allowed us to establish a preliminary structure model of these SEs. However, due to the low scattering intensity of lithium atoms, the location of excess Li cations is unknown. We propose to carry out high quality total neutron scattering to determine both the local and long-range structure present in these materials.