Operando electrochemical pressiometry probing interfacial evolution of electrodeposited thin lithium metal anodes for all-solid-state batteries

• Thin Li metal anodes (∼ 10 μm) were fabricated by scalable electrodeposition. • In/Li x In protective layer was coated on Li metal surface via electroless plating. • The Li-solid electrolyte side reactions and penetrating Li growth were alleviated. • Interfacial evolution was probed via operando electrochemical pressiometry. All-solid-state Li metal batteries with ultimate energy density require stabilization at the Li/solid electrolyte interfaces. Further, the use of conventional thick (hundreds of μm) Li metal anodes (LMAs) hinders an impartial evaluation of full cells. In this study, interfacial evolution is compared for thin LMAs (∼ 10 μm thick) prepared by a scalable electrodeposition, with varying protective In/Li x In layer formed via electroless plating. The positive effects of the In/Li x In layer are confirmed for both Li/Li 6 PS 5 Cl/Li symmetric cells and LiNi 0.70 Co 0.15 Mn 0.15 O 2 /Li 6 PS 5 Cl/Li full cells. Complementary analysis including electrochemical, ex situ X-ray photoelectron spectroscopy, operando electrochemical pressiometry, and cross-sectional scanning electron microscopy measurements discloses complex Li/Li 6 PS 5 Cl interfacial evolutions affected by the In/Li x In coatings, that is, suppressed side reactions and penetrating Li growth. Importantly, a new indicator from operando electrochemical pressiometry analysis, the capacity-normalized pressure change difference Δ(ΔP Q ) successfully predicts the dendritic growth of Li during cycling of LiNi 0.70 Co 0.15 Mn 0.15 O 2 /Li full cell.