Chlorine-rich lithium argyrodite enables stable interfacial Li plating/stripping behavior in anode-free all-solid-state batteries

Abstract

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 Li₆PS₅Cl (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.