Lithium Plating and Stripping Facilitated by Thin Sputtered Silver and Carbon Interlayers in Anode-Free All-Solid-State Batteries

Abstract Solid-state batteries (SSBs) with Li metal anodes offer higher energy density than conventional lithium-ion batteries, but Li anodes present both manufacturing and subsequent cycling challenges. Anode-free configurations mitigate some of the manufacturing issues by plating Li onto a current collector to form the anode during the first charge; however, any uneven Li deposition and subsequent stripping leads to low Coulombic efficiency during cycling and promotes Li dendrite formation and associated early cell failure. We study Li plating and stripping in an anode-free SSB configuration using an interlayer composed of a 100 nm Ag film sputtered onto a 1 μm particulate carbon layer on a Cu current collector, easily manufactured using laboratory standard equipment and materials. During charging, Ag reduced the overpotential for the onset of Li plating and facilitated Li deposition at the Cu/C interface. Cross-sectional microscopy tracked the evolution of the anodic interface during cycling and demonstrated the formation of a dense Li layer during charging but incomplete stripping during discharge, resulting in micro-cavity formation and decreased Li utilization. Anode-free full cells using the sputtered Ag/C bilayer, a Li–Ni–Mn–Co oxide (NMC) cathode, and a sulfide electrolyte had a capacity >200 mA h/g, representing a 25% increase over a C-only interlayer, and an initial Coulombic efficiency of 86%. These findings highlight the catalytic efficiency of Ag and C even in thin but readily scalable and easily prepared layers.