Designing 3D Nanoporous Cu/Cu₂O (Bi) with Bimodal Porosity as a High-Rate and Capacity Zinc Anode Host

We report a bimodal nanoporous Cu/Cu₂O doped with bismuth (np-Cu/Cu₂O (Bi)) by dealloying an Al-Cu-Bi-based two-phase precursor alloy. Different from the typically used unimodal porous Cu, the bimodal structure provides big pores (hundreds of nanometers) for enough Zn deposition (high capacity) and small pores (10 nm) with a high specific surface area for high rates. Moreover, the formation of the Cu₂O surface with Bi doping significantly reduces the Zn deposition overpotential. The np-Cu/Cu₂O (Bi)-based half cells and symmetric cells exhibit much lower Zn deposition overpotential (88.7 mV) and excellent cycling stability (over 260 h), respectively, even at a large current density of 50 mA cm^-2, obviously outperforming the pure Zn-based cells and most reported results. The dendrite issue and side reaction are also largely limited by the bimodal nanoporous structure design and surface modification. This work provides inspiration for developing an advanced Zn anode through porosity design and surface chemistry modulation.