Anode‐Free Lithium Metal Batteries Based on an Ultrathin and Respirable Interphase Layer

Abstract Anode‐free lithium (Li) metal batteries are desirable candidates in pursuit of high‐energy‐density batteries. However, their poor cycling performances originated from the unsatisfactory reversibility of Li plating/stripping remains a grand challenge. Here we show a facile and scalable approach to produce high‐performing anode‐free Li metal batteries using a bioinspired and ultrathin (250 nm) interphase layer comprised of triethylamine germanate. The derived tertiary amine and LixGe alloy showed enhanced adsorption energy that significantly promoted Li‐ion adsorption, nucleation and deposition, contributing to a reversible expansion/shrinkage process upon Li plating/stripping. Impressive Li plating/stripping Coulombic efficiencies (CEs) of ≈99.3 % were achieved for 250 cycles in Li/Cu cells. In addition, the anode‐free LiFePO4 full batteries demonstrated maximal energy and power densities of 527 Wh kg−1 and 1554 W kg−1, respectively, and remarkable cycling stability (over 250 cycles with an average CE of 99.4 %) at a practical areal capacity of ≈3 mAh cm−2, the highest among state‐of‐the‐art anode‐free LiFePO4 batteries. Our ultrathin and respirable interphase layer presents a promising way to fully unlock large‐scale production of anode‐free batteries.