Ultrafast and Scalable Fabrication of Cu–CuxO Nanostructures for Stabilizing Lithium Metal Anodes via Flashlight Irradiation

Three-dimensional porous nanoarchitectures on current collectors are effective for stabilizing Li metal anodes. However, developing these nanostructures in a simple and cost-effective manner is challenging. To address this, we propose a flashlight-based ultrafast and scalable method for manipulating nanoarchitectures on Cu foil. Cu(OH)₂ nanorods directly grown on Cu foil that are exposed to a flashlight can be photothermally activated to undergo ultrafast phase conversion to a mixed phase of Cu and Cu_xO while minimizing their structural collapse. The transformed hybrid nanorods have a sufficient pore volume, a large lithiophilic surface, and efficient electrical conduction to stabilize the lithium anode, thereby improving the long-term cycling stability and rate performance of the Li metal battery. Notably, capacity retention is observed to be ∼96% after 200 cycles at 0.5 C and ∼70% of its maximum capacity under a high-rate condition (5 C). Our simple approach enables ultrafast, large-area fabrication of nanoarchitectures that can stabilize the Li metal anode. We believe that further development in conjunction with a roll-to-roll process will accelerate the commercialization of Li metal batteries.