Large-area dendrite-free ultrathin Li-rich 3D Li-Sn alloy/graphene foil for high-performance all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) are highly sought after due to their inherent high energy density. However, the low stability of lithium metal with solid-state- electrolytes (SSEs) and the severe problem of lithium dendrites limit the lifespan of ASSLSBs. Here, we propose a large-area, ultrathin, and free-standing Li-rich anode (3D Li-Sn alloy/GF) for ASSLSBs, featuring a Li-Sn alloy foil (10–50 μm in thickness) supported by a three-dimensional (3D) graphene framework (GF). The high strength and 3D continuous structure of graphene ensure stable contact at the anode/SSE interface during delamination. Thanks to its high specific surface area, lithiophilic Li 22 Sn 5 nucleation sites can be uniformly distributed within the alloy phase, making lithium ions preferentially deposit towards the interior of the phase during lithium plating. The obtained lithium-rich alloy anode demonstrates an ultra-high lithium content (3282 mAh g −1 ) and a low potential platform (0.03 V vs. Li/Li + ), ensuring high energy density. This results in a long lifespan of up to 1200 h and a high critical current density of 4 mA cm −2 . The ASSLSBs exhibit excellent room-temperature cycling stability, with a capacity retention rate of 97.8 % after 235 cycles. Even with a high sulfur loading of 3.53 mg cm −2 , the anode maintains a high areal capacity of >3 mAh cm −2 , showcasing its potential for safe, long-life, high-energy-density ASSLSBs.