Constructing Calcium-Rich SEI and H₂O-Poor EDL Enables Stable Zinc-Ion Pouch Cells

Aqueous zinc-ion batteries (AZIBs) enable eco-friendliness, inherent safety, and low-cost energy storage, but they suffer from interfacial issues of Zn anode, which depends on the electrochemical behaviors in both solid electrolyte interphase (SEI) and electric double layer (EDL). Here, we introduce calcium l-aspartate (Ca-ASP), a bifunctional electrolyte additive that constructs calcium-rich SEI and H2O-poor EDL for stable zinc-ion pouch batteries. Ca2+ forms an inorganic SEI at the zinc anode interface and regulates Zn2+ diffusion via electrostatic shielding, while ASP– restructures the EDL to promote uniform zinc deposition. As a result, the zinc anode demonstrates exceptional performance with over a 4000 h cycle life and stable 300 h operation at a discharge depth of 86.2%. The Zn||NH4V4O10 full cells after 2000 cycles maintain 81.03% capacity. Furthermore, zinc-ion pouch cells enable stable cycling over 600 cycles without capacity decay. This work provides an effective solution for achieving stable zinc-ion pouch cells.