Homogenizing Zn Deposition in Hierarchical Nanoporous Cu for a High‐Current, High Areal‐Capacity Zn Flow Battery
Yang Li, Liangyu Li, Yunhe Zhao, Canbin Deng, Zhibin Yi, Diwen Xiao, Nauman Mubarak, Mengyang Xu, Jie Li, Guangfu Luo, Qing Chen, Jang‐Kyo Kim
Abstract
Abstract A Zn anode can offset the low energy density of a flow battery for a balanced approach toward electricity storage. Yet, when targeting inexpensive, long‐duration storage, the battery demands a thick Zn deposit in a porous framework, whose heterogeneity triggers frequent dendrite formation and jeopardizes the stability of the battery. Here, Cu foam is transferred into a hierarchical nanoporous electrode to homogenize the deposition. It begins with alloying the foam with Zn to form Cu 5 Zn 8 , whose depth is controlled to retain the large pores for a hydraulic permeability ≈10 −11 m 2 . Dealloying follows to create nanoscale pores and abundant fine pits below 10 nm, where Zn can nucleate preferentially due to the Gibbs–Thomson effect, as supported by a density functional theory simulation. Morphological evolution monitored by in situ microscopy confirms uniform Zn deposition. The electrode delivers 200 h of stable cycles in a Zn–I 2 flow battery at 60 mAh cm −2 and 60 mA cm −2 , performance that meets practical demands.