Achieving Ah-Level Zn-MnO₂ Pouch Cells via Interfacial Solvation Structure Engineering

Aqueous zinc-ion batteries (AZIBs) offer a safe, cost-effective, and high-capacity energy storage solution, yet their performance is hindered by interfacial challenges at the Zn anode, including hydrogen evolution, corrosion, and dendritic Zn growth. While most studies focus on regulating Zn²⁺ solvation structures in bulk electrolytes, the evolution of interfacial solvation-where Zn²⁺ undergoes desolvation and deposition-remains insufficiently explored. Here, we introduce sulfated nanocellulose (SNC), an anion-rich biopolymer, to tailor the interfacial solvation structure without altering the bulk electrolyte composition. Using in situ attenuated total reflection Fourier transform infrared spectroscopy and fluorescence interface-extended X-ray absorption fine structure, we reveal that SNC facilitates the formation of a low-coordinated Zn²⁺ solvation shell at the interface by weakening H₂O coordination. This transformation is driven by electrostatic interactions between Zn²⁺ and anchored sulfate groups, thereby reducing water activity, improving interfacial stability during charge/discharge, and suppressing parasitic reactions. Consequently, a high average coulombic efficiency of 99.6% over 500 cycles in Zn|Ti asymmetric cells and 1.5 Ah pouch cells (13.4 mg cm^-2 loading, remained stable over 250 cycles) were achieved in SNC-induced AZIBs. This work underscores the importance of interfacial solvation structure engineering-beyond traditional bulk electrolyte design-in enabling practical, high-performance AZIBs.