Tailoring argyrodite electrolyte for enhanced interface compatibility with lithium anode

Owing to high ionic conductivity and favorable deformation, lithium argyrodite-type sulfide solid electrolyte emerges as a prime candidate for next-generation all-solid-state lithium metal batteries. However, rampant side reactions and Li dendrite growth pose significant challenges for Li/Li₆PS₅Cl interface stability. In the study, an argyrodite-type electrolyte was tailored with greater Cl occupancy (90.01 %) on the anion sites of crystal lattice to boost anode interface stability besides balancing high ionic conductivity. It is demonstrated that the electrolyte could contribute Cl from 4d sites at the cost of its surface self-decomposition during the electrochemical process, thus, in situ inducing a LiCl-enriched interphase on the Cl-modified electrolyte. Taking advantage of favorable electron shielding and low migration barrier of LiCl species, the regulated interface structure relieves the electrolyte of severe degradation and suppresses Li dendrite growth via obstructing electron disturbance, with a concomitant of fast Li⁺ transport across the interface. With the tailored electrolyte, Li symmetric cell performs for 800 h at a current density of 0.5 mA cm⁻² without experiencing apparent short circuit. Moreover, the tailored electrolyte enables LCO||Li and LCO||Li-In cells with good cyclability over 550 cycles at 0.5 C and 10,000 cycles at 5 C, respectively.