Stability of the Argyrodite Electrolyte in Li-In Based All-Solid-State Batteries

Li-In alloy has been largely used as a working anode in all-solid-state full cells. Incorporating indium can help stabilize the interface by suppressing the decomposition of the solid electrolyte. However, the Li-In phase diagram is complex and involves multiple phases depending on the composition. Understanding the relationship between the Li-In composition and electrochemical performance as well as identifying the root causes of cell failure is crucial for advancing this technology. Here, we present a compressive analysis of the impact of the Li-In composition on the interfacial stability of the argyrodite electrolyte in all-solid-state batteries. The Li0.5In alloy, composed of LiIn and In phases, significantly improves the interfacial stability. In contrast, when using the Li-In or Li metal anode, we observe the accumulation of large Li deposits within the solid electrolyte as well as a thick interface composed of Li2S, leading to a shortened cycle life. The Li0.5In anode enables a high critical current density of 2.0 mA cm(-2) and extends cycling for 1000 h at 0.5 mA cm(-2). Additionally, a reversible capacity of 120 mAh g(-1) is achieved over 700 cycles in the LiCoO2|Li6PS5Cl|Li0.5In full cell.