AgPF₆ modified lithium interphases enable superior performance for Li_5.5PS_4.5Cl_1.5-based all-solid-state lithium metal batteries

All-solid-state lithium metal batteries (ASSLMBs) hold tremendous promise as next-generation energy storage devices due to their remarkable energy densities. Nevertheless, uncontrolled growth of lithium dendrites resulting from nonuniform deposition and significant volume expansion hinders the commercial application of ASSLMBs. Herein, we designed an AgPF₆ modified lithium composite anode to stabilize the interface between the lithium metal anode and Li_5.5PS_4.5Cl_1.5 electrolytes. The optimal AgPF₆ modified lithium composite accelerates Li diffusion within bulk lithium anode and facilitates the uniform deposition for lithium metal during the electrochemical process due to the generation of LiF-interface and Li–Ag alloy, which restricts the accumulation of inactive lithium. The enhanced compatibility between Li metal and sulfide electrolyte have been confirmed in both symmetric cells and ASSLMBs. The assembled AgPF₆@Li/Li_5.5AgPS_4.5Cl_1.5/AgPF₆@Li cells shows a high critical current density value of 2.1 mA cm⁻² and a stable lithium stripping/platting behavior up to 400 h at 0.1 mA cm⁻². The LiNi_0.6Mn_0.2Co_0.2O₂/Li_5.5PS_4.5Cl_1.5/AgPF₆@Li battery delivers an initial discharge capacity of 113.5 mAh g⁻¹ at 0.5C with superior capacity retention of 77.0% after 500 cycles at room temperature. This work proposes an effective strategy in designing composite lithium metal employing in sulfide-based ASSLMBs to achieve favorable energy density and excellent cyclability.