Origin and Solution of Poor Cell-to-Cell Reproducibility in Zinc Metal Anodes at High Areal Capacity

Cell-to-cell reproducibility is a critical bottleneck in translating metal batteries from laboratory demonstrations toward commercial products, yet it remains poorly understood. Here, we find that the cell-to-cell reproducibility of zinc metal anodes decreases significantly at high areal capacities. We further identify that substrate imperfections reduce the physical adhesion between the deposit and the substrate, thereby accounting for the poor cell-to-cell reproducibility. This weak physical adhesion originates from early zinc nuclei at tips, which then grow uncontrollably along the imperfect surface, resulting in interfacial void formation. These voids may induce "micro-reactor-like reactions", further weakening the mechanical interaction. We overcome this challenge by introducing tetramethylammonium cations to regulate the early nucleation process by filling gaps in between, thereby maintaining strong mechanical adhesion. As a result, the cell-to-cell reproducibility of the zinc metal anodes is improved by fivefold and pouch-cell configurations are demonstrated at ultrahigh areal capacity conditions. A 6.8-Ah Zn||VO₂ pouch cell delivers a high areal capacity of 6.3 mAh cm^-2, while a 2.2-Ah Zn||MnO₂ pouch cell shows a high areal capacity of 5.1 mAh cm^-2, indicating its readiness toward practical-scale applications. Our findings on the mechanical adhesion would accelerate the commercialization of zinc metal batteries.