High‐Power and Large‐Area Anodes for Safe Lithium‐Metal Batteries

Abstract The lithium deposited via the complex electrochemical heterogeneous lithium deposition reaction (LDR) process on a lithium foil‐based anode (LFA) forms a high‐aspect‐ratio shape whenever the reaction kinetics reach its limit, threatening battery safety. Thereby, a research strategy that boosts the LDR kinetics is needed to construct a high‐power and safe lithium metal anode. In this study, the kinetic limitations of the LDR process on LFA are elucidated through operando and ex situ observations using in‐depth electrochemical analyses. In addition, ultra‐thin (≈0.5 µm) and high modulus (≥19 GPa) double‐walled carbon nanotube (DWNT) membranes with different surface properties are designed to catalyze high‐safety LDRs. The oxygen‐functionalized DWNT membranes introduced on the LFA top surface simultaneously induce multitudinous lithium nuclei, leading to film‐like lithium deposition even at a high current density of 20 mA cm −2 . More importantly, the layer‐by‐layer assembly of the oxygen‐functionalized and pristine DWNT membranes results in different surface energies between the top and bottom surfaces, enabling selective surface LDRs underneath the high‐modulus bilayer membranes. The protective LDR on the bilayer‐covered LFA guarantees an invulnerable cycling process in large‐area pouch cells at high current densities for more than 1000 cycles, demonstrating the practicability of LFA in a conventional liquid electrolyte system.