Silver exsolution from Li-argyrodite electrolytes for initially anode-free all-solid-state batteries

Achieving stable cyclability in initially anode-free all-solid-state batteries is challenging due to non-uniform Li (de)plating, especially under practical operating conditions. Here, we introduce a bilayer comprising a silver(Ag)-doped Li-argyrodite electrolyte layer in contact with the undoped Li-argyrodite electrolyte. During charging, electrochemical exsolution of Ag⁺ from the silver-doped Li argyrodite forms nanoscale, lithiophilic silver seeds along grain boundaries and in pores where they are accessible for electron transfer. These silver seeds alloy with Li to induce uniform Li plating underneath and return to the electrolyte layer upon Li stripping to enhance the reversibility during cycling. With silver exsolution, a pouch-type full-cell with a volumetric energy density of 1312 Wh L^-1 (excluding the packaging materials) and areal discharge capacity of 7.0 mAh cm^-2 at 0.7 mA cm^-2, demonstrated stable cycling at a practical stack pressure of 2.0 MPa. This study highlights that Ag⁺ diffusion in the Li-argyrodite solid electrolyte and its electrochemical exsolution are an effective strategy for robust, high-energy-density initially anode-free all-solid-state batteries.