Synergistic Effect of 3D Current Collectors and ALD Surface Modification for High Coulombic Efficiency Lithium Metal Anodes

Abstract

Improving the performance of Li metal anodes is a critical bottleneck to enable next‐generation battery systems beyond Li‐ion. However, stability issues originating from undesirable electrode/electrolyte interactions and Li dendrite formation have impaired long‐term cycling of Li metal anodes. In this work, we have developed a bottom‐up fabrication process of vertically aligned and highly uniform Cu pillar arrays on a Cu foil via templated electrodeposition for use as a 3D current collector.[1] By rationally controlling geometric parameters of the 3D current collector architecture, including pillar diameter, spacing, and length, we have demonstrated the morphology of Li plating/stripping upon cycling can be controlled and optimal cycling performance can be achieved. In addition, we showed that deposition of an ultrathin layer of ZnO by atomic layer deposition on the current collector surface can facilitate the initial Li nucleation, which dictates the morphology and reversibility of subsequent cycling. This core–shell pillar architecture allows for the effects of geometry and surface chemistry to be decoupled and individually controlled to optimize the electrode performance in a synergistic manner. Using this model platform, we have demonstrated Li metal anodes with Coulombic efficiency up to 99.5% at 0.5 mA/cm2 and 99.4% at 1 mA/cm2, which are among the highest reported values to date. The results gained from this work can thus provide a pathway toward high‐efficiency and long‐cycle life Li metal batteries with reduced excess Li loading. [1] K.-H. Chen, A.J. Sanchez, E. Kazyak, A.L. Davis, N.P. Dasgupta, Adv. Energy Mater. 9, 1802534 (2019).