Stable Li Metal Anode Enabled by Space Confinement and Uniform Curvature through Lithiophilic Nanotube Arrays

Abstract

The application of lithium (Li) metal anodes in rechargeable batteries is primarily restricted by Li dendrite growth on the metal’s surface, which leads to shortened cycle life and safety concerns. Herein, well‐spaced nanotubes with ultrauniform surface curvature are introduced as a Li metal anode structure. The ultrauniform nanotubular surface generates uniform local electric fields that evenly attract Li‐ions to the surface, thereby inducing even current density distribution. Moreover, the well‐defined nanotube spacing offers Li diffusion pathways to the electroactive areas as well as the confined spaces to host deposited Li. These structural attributes create a unique electrodeposition manner; i.e., Li metal homogenously deposits on the nanotubular wall, causing each Li nanotube to grow in circumference without obvious sign of dendritic formation. Thus, the full‐cell battery with the spaced Li nanotubes exhibits a high specific capacity of 132 mA h g−1 at 1 C and an excellent coulombic efficiency of ≈99.85% over 400 cycles.This work presents a technique for suppressing lithium dendrite formation through ultrauniform curvature and space confinement. Lithium uniformly deposits/dissolves on the nanotube surfaces where the local current distribution is uniform due to the ultrauniform curvature. The nanotube spacing provides confined spaces to host deposited lithium. Thus, a full‐cell battery with spaced lithium nanotubes shows excellent specific capacity at high rates.