Plasma-enhanced SnO2-x thin films on copper current collector for safer lithium metal batteries

Anode-free lithium batteries are a safer and lighter alternative, because they eliminate the traditional host anode for lithium ions, thereby enhancing energy density and reducing the battery weight. However, challenges like dendritic growth and electrolyte decomposition persist, affecting battery lifespan. Here, we present a scalable technique using plasma enhanced chemical vapor deposition (PECVD) of a tin(IV) precursor to directly deposit an artificial solid electrolyte interface (SEI) on the copper current collector. The obtained SnO2-x coatings, modified by oxygen plasma, exhibited remarkable electrochemical properties. X-ray photoelectron spectroscopy (XPS) is employed to examine the surface composition and impact of plasma treatment, while long-term cycling and electrochemical impedance spectroscopy (EIS) confirm battery durability. Scanning electron microscopy (SEM) and contact angle measurements elucidate coating homogeneity, with lithium nucleation overpotential during first cycle providing further evidence for homogeneity during lithium de-/plating.