(Invited) Stable Anode-Free All-Solid-State Lithium Battery through Tuned Metal Wetting on the Copper Current Collector

Abstract

It is demonstrated that a standard copper foil current collector with appropriately modified surface chemistry will allow for stable lithium cycling in an anode-free all-solid-state lithium battery (AF-ASSB). An argyrodite solid electrolyte Li6PS5Cl (LPSCl) is employed without any modifications or secondary interlayers. The tuned lithophilic copper surface allows for stable plating and stripping, reducing the overpotentials and significantly improving the Coulombic efficiency (CE). During continuous plating experiments using half-cells (1 mA cm-2), the accumulated thickness of electrodeposited Li on Li2Te-Cu is more than 70 μm, which is the thickness of Li foil counter-electrode. Full AF-ASSB with NMC811 cathode delivers an initial CE of 83% at 0.2C, with a cycling CE above 99%. Post-mortem cryo-FIB-SEM analysis demonstrates uniform electrodeposited metal microstructure, with no signs of voids or dendrites at the collector-SE interface. The same copper current collector but unmodified leads to inhomogeneous Li plating, with “dead metal” formation and an irregular honeycomb-like solid electrolyte interphase (SEI) interspersed with pores. Density functional theory and mesoscale calculations provide complementary insight regarding nucleation-growth behavior. Unlike for conventional liquid-electrolyte metal batteries, the role of current collector/support lithiophilicity has not been explored for emerging AF-ASSBs. Figure 1