Vacuum dealloyed brass as Li-metal battery current collector: Effect of zinc and porosity

“Anode-free” lithium-metal batteries promise significantly higher energy density than conventional graphite-based lithium-ion batteries; however, lithium dendrite growth can lead to internal short circuits with associated safety risks. While porous current collectors can suppress dendrite growth, optimal porosity and composition remain unknown. Here, we show that the temperature during vapor phase dealloying (VPD) of α-brass (Cu₆₃Zn₃₇) controls the surface Zn concentration, decreasing from 8% to below 1% from 500 – 800°C. The surface composition is controlled by the temperature-dependent diffusion. A battery cell maintains > 90% Coulombic efficiency (CE) over 100 cycles when the Zn content is the lowest, whereas the higher-Zn samples degraded to ∼70% CE. The difference in surface composition has hence dramatic effects on battery performance, and our results demonstrate how precise compositional control enables stable Li-metal battery operation, establishing ∼1 at.% surface Zn as optimal for preventing capacity fading and uniform lithium plating, while establishing predictive relationships between processing temperature and surface composition. This work provides design rules for multifunctional current collectors and demonstrates scalable VPD production for next-generation batteries.