Interfacial analysis of in-situ anode formation in solid-state batteries with nanometric current collector

Li preferentially nucleates along polishing lines acting as surface defects helping to spread Li all over the surface. • Sputtering nanometric Cu on LLZO is an efficient method to fabricate anode-less Solid-State Batteries. • The polishing procedure smoothen the electrolyte surface to ensure uniform deposition of Cu current collector and Li. • The low interfacial resistance of plated Li compared with Li foil evidences the improved interface between Cu and LLZO. • Anode-less half cells with 50 nm sputtered Cu cycled for 100 of cycles without pressure. • Interfacial resistance of electroplated Li decreased significantly while going from nucleation to growth process. • Morphology and sites of electrodeposited Li can vary depending upon the current collector thickness. Anode-less solid-state batteries are at the technological forefront of electrochemical storage devices, addressing challenges associated with the processing of thin Li metal anodes and offering potential for superior energy density and lower cost. While the removal of Li metal anode is a promising opportunity, several scientific hurdles remain, particularly the design of interfaces that enable uniform and reversible Li deposition. In this work, we engineered the surface of Li 7 La 3 Zr 2 O 12 solid electrolyte with a thin sputtered nanometric Cu layer to enhance the efficiency of reversible Li deposition. We investigated the nucleation and growth of Li as a function of the Cu layer thickness, which serves as a current collector for cycling the cells without the need of external pressure. The evolution of interfaces was studied during cycling to understand Li nucleation and growth. The morphology of electrodeposited Li was investigated with ex-situ scanning electron microscopy. It is demonstrated that the rational design and engineering of nanometric current collectors is key to develop ceramic electrolyte anode-less devices, laying the groundwork for future advancements in this promising concept.