Ultra‐Sleek High Entropy Alloy Tights: Realizing Superior Cyclability for Anode‐Free Battery

Abstract The development of Li‐free anodes to inhibit Li dendrite formation and provide high energy density Li batteries is highly applauded. However, the lithiophobic interphase and heterogeneous Li deposition hindered the practical application. In this work, a 20 nm ultra‐sleek high entropy alloy (HEA, NiCdCuInZn) tights loaded with HEA nanoparticles are developed by a thermodynamically driven phase transition method on the carbon fiber (HEA/C). Multiple Li + transport paths and abundant active sites are enabled by the cocktail effect of different constituent elements in HEA. These active sites with gradient absorption energies (−3.18 to −2.03 eV) facilitate selective binding, providing a low barrier for homogeneous Li nucleation. Simultaneously, multiple transport paths promote Li diffusion behavior with uniform Li deposition. Thus, the HEA/C achieves high reversibility of Li plating/stripping processes over 2000 cycles with a coulombic efficiency of 99.6% at 5 mA cm −2 /1 mAh cm −2 in asymmetric cells, as well as over 7200 h at 60 mA cm −2 /60 mAh cm −2 in symmetric cells. Moreover, the anode‐free full cell with the HEA/C host has an average coulombic efficiency of 99.5% at 1 C after 160 cycles. This advanced HEA structure design shows a favorable potential application for anode‐free Li metal batteries.