Manipulating Interphase Chemistry for Aqueous Zn Stabilization: The Role of Supersaturation

Abstract The limited cycling durability of Zn anode, attributed to the absence of a robust electrolyte‐derived solid electrolyte interphase (SEI), remains the bottleneck for the practical deployment of aqueous zinc batteries. Herein, we highlight the role of local supersaturation in governing the fundamental crystallization chemistry of Zn 4 SO 4 (OH) 6 ⋅xH 2 O (ZSH) and propose a subtle supersaturation‐controlled morphology strategy to tailor the interphase chemistry of Zn anode. By judiciously creating local high‐supersaturation environment with organic caprolactam to manipulate the precipitation manner of zinc sulfate hydroxide (ZSH), lattice‐lattice matched heterogeneous nucleation of ZSH (001) and Zn (002) is realized in aqueous ZnSO 4 , producing a dense, pseudo‐coincidence interface capable of functioning as decent SEI. The plating/stripping efficacy of Zn is significantly boosted, as reflected by the great improvement of the initial (from 59.9 % to 84.1 %) and average (from 94.0 % to 99.2 %) coulombic efficiency. Accordingly, the cyclic endurance of Zn anode is prolonged from 50 h to over 7000 h at 0.5 mA cm −2 /1 mAh cm −2 , witnessing 140‐fold lifespan extension. Profiting from supersaturation‐mediated Zn stabilization, the performance deterioration of zinc‐vanadium batteries is also alleviated, even with a low N/P ratio of 4.4. This work is anticipated to deepen current understanding on the control of the anodic chemistry.