Hanyang University Determines Minimum Effective Thickness for Cathode Protection Layer in Sulfide-Based Solid-State Batteries

A research team led by Professor Tae Joo Park from the Department of Materials Science and Chemical Engineering at Hanyang University in South Korea has systematically investigated the minimum effective thickness of cathode protective layers in sulfide-based all-solid-state batteries (ASSBs). These batteries, which employ solid-state electrolytes, hold promise for enhanced safety and energy density. However, chemical incompatibility exists at the interface between the cathode active materials and the sulfide electrolyte. A common approach to mitigate side reactions is to coat the cathode surface with a protective layer. Previous studies suggested that such layers should be kept below 5 nanometers to maintain lithium-ion transport and interfacial stability, yet the precise minimum effective thickness remained unclear. The team experimentally determined the minimal thickness required for effective protection, providing quantitative guidance for interface design. Their findings have been published in the journal *Energy Storage Materials*.