Tip-localized stack pressure field distribution towards inactive Zn loss reduction for reversible zinc metal batteries

Zero-valent metallic zinc (Zn)-dominant inactive Zn loss is a key factor influencing the reversibility of electrochemical plating/stripping reactions in the Zn metal anode of Zn batteries. Current research in this field primarily focuses on strategies for tuning electrochemical reactions to suppress Zn dendrite growth and electrolyte decomposition. However, the correlation between inactive Zn loss and physical tuning methods, especially the effect of the straightforward and efficient mechanical stack pressure that does not require chemical modifications to the electrode or electrolyte, has rarely been studied. Herein, we investigate the quantitative relationship between stack pressure and inactive Zn formation and discover the effect of a tip-centralized pressure field applied to Zn deposition particles during stacking, modifying vertical dendritic Zn deposition to a dense, uniform structure. Simultaneously, homogeneous Zn stripping and reduced inactive Zn formation are achieved owing to stack pressure. Under an optimal stack pressure of 867 kPa, we obtain a notable reduction of 86.93 % in the inactive metallic Zn loss amount, along with a 500 % increase in the cycle life in the half-cell. These findings on the mechanism and structure-performance relationship of stack pressure-tailored inactive Zn formation provide critical theoretical insights for constructing efficient Zn metal batteries.