Ag-modification argyrodite electrolytes enable high-performance for all-solid-state lithium metal batteries

Solid-state batteries combined with high-voltage layered cathode and lithium metal anode display good safety and high energy density, showing great potential as next-generation energy storage devices. However, the low ionic conductivity and poor stability with lithium metal of most solid electrolytes inhibit the development of solid-state lithium metal batteries. Herein, Ag+ is successfully integrated into Li5.5PS4.5Cl1.5 structure with improved ionic conductivity and better lithium metal stability for the yielded Li5.5-xAgxPS4.5Cl1.5 (x = 0, 0.02, 0.05, 0.10) electrolytes. Ag+ dopant is carefully tailored to achieve the optimal Li5.45Ag0.05PS4.5Cl1.5 electrolyte with a high Li-ion conductivity of up to 9.1 mS cm−1 and a large CCD value of 1.8 mA cm−2. The corresponding battery with LiNi0.6Mn0.2Co0.2O2 cathode and Li-In anode delivers a high initial discharge capacity of 154.9 mAh g−1 at 1.0C and maintains 94.5% of this value after 100 cycles. However, the same cathode shows low discharge capacities and fast degradation of capacities with bare lithium metal anode in solid-state batteries. A facial 3D host lithium metal with Ag and LiNO3 particles on the surface is designed as the anode for this battery, showing much higher capacities and superior cyclability at different C-rates. The corresponding battery delivers discharge capacities of 140.6 mAh g−1 and 105.4 mAh g−1 when cycled at 0.1C and 0.5C. These superior electrochemical performances are attributed to the dual modification of Ag+ both in solid electrolytes and lithium metal anodes.