Deposition and Confinement of Li Metal along an Artificial Lipon-Lipon Interface

Lithium phosphorus oxynitride (Lipon) is an amorphous solidstate electrolyte that can completely suppress Li penetration from the anode to the cathode, commonly referred to as dendrites. The key to the Lipon performance is thought to be its homogeneous and pore-free morphology. To test this, we present a modified thin film battery configuration with a lithium cobalt oxide cathode, a Lipon electrolyte, and a top layer with a copper current collector and an artificial Lipon-Lipon interface parallel to the cathode. Upon electrochemical cycling, Li metal rapidly deposits at the edge of this Cu current collector and then proceeds to plate along the 2D Lipon-Lipon interface. As the Li is confined to this 2D plane, it confirms the ability of Lipon to suppress Li penetration. It also demonstrates that the homogeneous interface-free morphology of Lipon is key to its performance.