Pyrrole-enabled free water activity suppression and zincophilic-hydrophobic interfacial engineering for highly stable Zn metal anode

Aqueous zinc-ion batteries (AZIBs) have shown significant potential, however, their large-scale application is hindered by the active water-induced dendrite growth, hydrogen evolution reaction (HER), corrosion, and passivation on the Zn anode surface. Herein, pyrrole (Py) was introduced as an additive in the ZnSO 4 electrolyte to enhance the reversibility and stability of Zn 2+ deposition/stripping. The results demonstrated that Py effectively reduces the activity of free water outside the Zn 2+ solvation shell and in situ forms a polypyrrole (PPy)-rich interfacial layer on zinc surface with zincophilic and hydrophobic properties. The above synergy effectively suppresses the activity of water and eventually promotes uniform Zn deposition. The electrochemical performance demonstrated that in the electrolyte with 100 ​mM ​Py, the Zn//Zn symmetric cell exhibited a stable cycle lifetime up to 3 130 ​h, and the Zn//Cu half-cell maintained a high Coulombic efficiency of over 99.5 ​% after 800 cycles. Furthermore, the Zn//NVO@PPy full battery showed a high capacity retention of 73.9 ​% after 1 500 charge/discharge cycles at 3 ​A ​g −1 . Overall, the proposed Py additive not only reduced the free water activity, but also facilitated the formation of a stable hydrophobic-zincophilic interface layer, offering a promising strategy to improve the performance of Zn anodes in AZIBs.