Aqueous Zinc-Ion Pouch Cells: From Failure Mechanisms to Practical Solutions.

Aqueous zinc-ion batteries (AZIBs) have been regarded as promising candidates for stationary energy storage owing to their low cost, inherent safety, and high volumetric energy density. To fully leverage these advantages in practical applications, the pouch cell configuration offers a favorable design with compactness and lightweight packaging. Nonetheless, commercial viability remains limited by inadequate cycling stability in pouch cells, despite the extended cycle life achieved in coin cells. In this review, we emphasize the performance gap between materials-level coin cells and device-level pouch cells and elucidate the failure mechanisms in pouch-type zinc-ion batteries. These mechanisms include internal short-circuits caused by severe zinc dendrite growth under high area capacity conditions, and high polarization resulting from by-product accumulation and hydrogen evolution due to water-induced corrosion. We then comprehensively review recent progress in zinc-ion pouch cells, highlighting strategies such as artificial protective layers on the Zn anode, separator modifications, and electrolyte design. Finally, we propose a future research direction to advance and commercialize zinc-ion battery technology.