Engineering Current Collector with 2D TiO₂ Nanosheets for Stable Lithium Metal Batteries

Abstract The formation of lithium dendrites, driven by the non‐uniform deposition of lithium, remains a critical challenge for the performance and safety of lithium metal batteries. To address this issue, we engineer the surface of copper current collectors by depositing ultra‐thin 2D TiO2 nanosheets with varying thicknesses (0–1200 nm) as a protective layer. Half‐cells without the 2D TiO2 coating exhibit a significant decline in Coulombic efficiency after only 65 charge‐discharge cycles. In contrast, the modified current collector with the smoothest surface achieves remarkable cycling stability, maintaining ~97.6 % Coulombic efficiency after 200 cycles. Full cells incorporating these nanosheets demonstrate a good discharge capacity of ~134 mAh/g after 150 cycles at a 1 C rate. The improved electrochemical performance is attributed to the high lithium affinity and reduced surface roughness of the current collector facilitated by the 2D TiO₂ buffer layer. These findings emphasize the crucial role of 2D TiO₂ nanosheets in regulating Li‐ion deposition, thereby significantly improving the cycling stability and performance of lithium metal batteries.