Homogenizing Interfacial Electric Fields through a Nanoporous CaSO4-Based Artificial SEI for Long-Lifespan Zinc Metal Anodes

Despite the high energy density, intrinsic safety, and low cost that render aqueous zinc-ion batteries attractive, their practical viability is compromised by capacity decay and internal short circuits-phenomena traceable to uncontrolled dendritic growth during non-uniform Zn stripping/plating. In this work, we propose a cost-effective nanoporous CaSO4 coating strategy to enable the uniform zinc deposition. In situ dendrite visualization, scanning electron microscopy, and laser confocal microscopy collectively corroborate its exceptional dendrite-suppression capability. The artificial interlayer's ability to homogenize the interfacial electric field underpins the remarkable cyclability of the Zn@CaSO4 symmetric cell. Consequently, it maintains stable operation for over 1700 h at 1 mA cm-2 and 1 mAh cm-2, a duration that represents a 16-fold improvement relative to an unmodified Zn electrode. Furthermore, extended cycling reveals the durability of the Zn@CaSO4||MnO2 configuration. At a current density of 1 A g-1, it maintains a specific capacity of 158 mAh g-1 over 1000 cycles, achieving a capacity retention as high as 72.7%. The study pioneers nanoporous CaSO4 as a low-cost, eco-friendly, and readily scalable protective layer for Zn anodes, significantly enhancing cycling stability and capacity retention.