Reversible Li plating/stripping of anode-free all-solid-state batteries is enabled by the synergistic effect of superionic Li 5.5PS 4.5Cl 1.5 and Li-alloying interlayer.
Anode-free all-solid-state batteries (AFASSBs) have the advantages of a simplified manufacturing process because of the absence of a lithium anode. Here, we systematically investigate the effect of various solid electrolytes (SEs) on the electrochemical properties of AFASSBs without stack pressure. The results show that argyrodites promote Li plating/stripping, whereas other SEs are rapidly degraded. Interestingly, Li 5.5PS 4.5Cl 1.5, with an ionic conductivity of 9.8 mS cm −1, provides better capacity and cyclability than Li 6PS 5Cl (4.3 mS cm −1), indicating that superionic halogen-rich Li-argyrodites are beneficial for AFASSBs. A model study based on a prelithiated current collector reveals that the elimination of the initial Li nucleation reaction further improves the interfacial stability of Li 5.5PS 4.5Cl 1.5. Consequently, the combination of Li 5.5PS 4.5Cl 1.5 and Ag–C achieves the highest coulombic efficiency owing to the synergistic effect of a chlorine-rich SE and an Li-alloying interlayer. These findings show the potential of utilizing superionic halogen-rich Li-argyrodites and alleviating the Li nucleation overpotential in AFASSBs.