Studies on the inhibition of lithium dendrite formation in sulfide solid electrolytes doped with LiX (X = Br, I)

A promising method to increase the energy density of all-solid-state batteries (ASSBs) featuring lithium ions as carriers is to employ Li metal as the anode. However, this has been accompanied by safety problems like flammable accidents associated with lithium dendrites originating from reactions with the solid electrolyte, leading to reduced battery performance. To overcome this issue toward the commercialization of ASSBs, various approaches have been proposed by many researchers. Among the suggested solutions, the use of lithium-halide doped Li3PS4, to suppress lithium dendrite formation, has attracted attention. LiI-doped Li3PS4 has shown the highest lithium dendrite growth suppression among lithium-halide-doped systems, but the reason for this is unclear. Thus, we attempted to clarify the cause of this suppression by comparing LiBr-doped Li3PS4 with LiIdoped Li3PS4. Investigation using various methods such as electrochemical evaluation, X-ray absorption spectroscopy, X-ray computed tomography, and pair distribution function analysis revealed that two factors affect the suppression of Li dendrite growth: the suppression of the current density distribution by improving the ionic conductivity and the stable interfacial layer. This is the main reason LiI-doped Li3PS4 shows excellent Li dendrite suppression.

Automated summary

To increase the energy density of all-solid-state batteries, researchers have proposed using Li metal as the anode. However, safety issues associated with lithium dendrites have been a concern. One proposed solution is to use lithium-halide doped Li3PS4 to suppress the formation of lithium dendrites. This study compared LiBr-doped Li3PS4 with LiI-doped Li3PS4 to investigate the reason for the excellent suppression of lithium dendrites by LiI. The results revealed that the suppression is due to the improvement of ionic conductivity and the formation of a stable interfacial layer.