Encapsulating Hollow Perovskite Fluorides in Atomic Mn‐Embedded N‐Doped Carbon Fibers for Anode‐Less 5 V‐Class Li Metal Batteries

Anode‐less Li metal batteries (ALLMBs) guarantee high energy density but face critical challenges such as dendrite growth, large volume change, and energy density sacrifice imposed by heavy Cu current collectors. Herein, we report a three‐dimensional (3D) lightweight host comprising N‐doped carbon macroporous fibers encapsulating atomically dispersed Mn‐N sites and hollow NaMg(Mn)F 3 cubes (NMMF@Mn/N‐CMFs) for ALLMBs. The well‐dispersed Mn‐N sites and hollow NMMF cubes function as lithiophilic nucleation sites to promote uniform Li nucleus growth on both the external and internal surfaces of the hollow fibers. The 3D macroporous networks and internal hollow structures mitigate structural stress and uniformize Li growth by accommodating volume change and decreasing local current density. As a result, the NMMF@Mn/N‐CMFs host displays an average Coulombic efficiency of 98.9% for 1500 cycles at 5.0 mA cm −2 . When paired with a LiNi 0.5 Mn 1.5 O 4 cathode, the assembled 5 V‐class anode‐less pouch cell delivers enhanced stability with 95.8% capacity retention over 120 cycles. Besides, a 0.31 Ah pouch cell under anode‐less conditions shows an energy density of 536 Wh kg −1 , calculated based on the active materials of electrodes.