Building π–π-conjugated molecule adsorption layer on Zn anode for ultra-stable aqueous zinc-ion batteries

The absence of a solid electrolyte interphase (SEI) to protect the Zn anode in an aqueous environment poses significant challenges for guaranteeing the long-term operation of aqueous zinc-ion batteries (AZIBs). Here, we solve this problematic issue by employing a representative additive, diaminobenzenesulfonic acid (DA), with a π–π-conjugated structure. Besides exerting the conventional regulatory effect of reshaping the solvation framework of Zn 2+ and reconfiguring the hydrogen bond network of the bulk electrolyte, the introduction of DA builds a unique π-π-conjugated adsorption layer on the Zn anode, which reduces the energy barrier for the electrolyte solvent decomposition, thereby promoting stable SEI formation to effectively safeguard the Zn anode against attack from corrosive electrolytes. Furthermore, the selective adsorption of DA directs ordered Zn(002) deposition, thereby fundamentally preventing the formation of Zn dendrites. Consequently, the Zn||Zn symmetric cell exhibits a lifespan of 400 h at both a high current density of 10 mA cm −2 and an areal capacity of 10 mAh cm −2 . Moreover, when coupled with a V 2 O 5 cathode, the Zn||V 2 O 5 full cell exhibits 93.6% capacity retention after 2000 cycles at 1 A g −1 . This study pioneers a promising strategy for developing stable and reversible Zn anodes based on an in-depth understanding of the correlation between additive molecular structures and Zn anode deposition performance. • Diaminobenzenesulfonic acid (DA) with the π-conjugated structure is utilized as an organic molecule additive in the ZnSO 4 electrolyte. • The unique π–π-conjugated adsorption layer on the Zn anode establishes a stable Zn anode interface. • The introduction of DA facilitates the formation of a robust SEI to protect Zn anode against electrolyte corrosion.