Anchoring Sn Nanoparticles in Necklace‐Like B,N,F‐Doped Carbon Fibers Enables Anode‐Less 5V‐Class Li‐Metal Batteries

Li metal batteries (LMBs), particularly with a limited Li metal anode and a 5V-class cathode, offer significantly higher energy density compared to the state-of-the-art Li-ion batteries. However, the limited Li anode poses severe challenges to cycling stability due to low efficiency and large volume expansion issues associated with Li. Herein, we design a lightweight and functionalized host composed of Sn nanoparticles embedded into necklace-like B,N,F-doped carbon macroporous fibers (Sn@B/N/F-CMFs) toward anode-less 5V-class LMBs. The macroporous framework can decrease the local current density to homogenize Li deposition and release structural stress to realize high areal capacity of over 40 mAh cm^-2. The lithiophilic B,N,F-doped carbon and Sn nanoparticles can function as high-affinity Li⁺ binding sites to uniformize Li nucleus growth on the internal and external surface of hollow fibers. Accordingly, the Sn@B/N/F-CMFs enable stable dendrite-free Li plating/stripping behaviors for 1700 h even in the carbonate-based electrolyte. When coupled with a 5V-class LiNi_0.5Mn_1.5O₄ cathode, the assembled anode-less pouch cell also displays stable cycling performance even under harsh conditions.