In Situ Nanoscale Visualization of Stripping-Induced Failure Behavior in Aqueous Zinc Batteries

Abstract

Aqueous zinc batteries (AZBs) show great promise for large-scale energy storage due to their low cost, intrinsic safety, and environmental compatibility. However, their practical deployment is hindered by dendrite formation, residual zinc (Zn) accumulation, and limited cycle life. Recent studies have identified the stripping process as a critical factor governing battery longevity, yet the underlying failure mechanisms remain poorly understood. In this study, leveraging a fourth-generation synchrotron radiation source, we employed in situ nanoscale X-ray microscopy to visualize the morphological evolution from planar to mossy Zn during cycling at 50 mA cm–2. Combining observations of the entire cycling process with optical flow analysis of the stripping process on different substrates at 1 mA cm–2, we categorize the origins of residual Zn into four distinct pathways: (i) dendrites formed during plating; (ii) dendrites generated by crystallographically selective stripping; (iii) bulky Zn that loses electrical contact during stripping; and (iv) Zn fragments resulting from inward dissolution. Ex-situ XRD and DFT calculations further confirm the preferential dissolution of Zn(100) and Zn(101) over Zn(002). These findings highlight the critical role of the stripping process in AZB failure and demonstrate that minimizing local variations in dissolution behavior through kinetic modulation is one of the keys to achieving complete dissolution and enhancing Zn reversibility.