In situ and operando characterisation of Li metal – Solid electrolyte interfaces

The use of lithium metal as the negative electrode holds great promise for high energy density solid-state batteries (SSBs) future, but at same time presents major technical challenges in their development. Li metal, with its reactivity, soft and ductile nature, propensity towards mechanical deformation during electrochemical cycling, is susceptible to formation various defects such voids, cracks filamentary deposits - solid electrolyte interface, that eventually cause rapid degradation cell performance. In order gain insights into these interfacial processes identify mechanisms failure, situ operando characterisation approaches are essential. this perspective, we present our opinions on current state techniques, while highlighting existing limitations scope methods. We also endeavour opportunities future research developing building better evaluate metal-solid interface so guide appropriate choice materials further enable efficient SSB architectures.