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

## TL;DR

This paper introduces sulfated nanocellulose to improve the performance of aqueous zinc-ion batteries by stabilizing the zinc anode interface.

## Contribution

The use of sulfated nanocellulose as an anion-rich additive to engineer the interfacial solvation structure of Zn anodes is novel.

## Key findings

- Sulfated nanocellulose reduces interfacial H2O activity and suppresses hydrogen evolution.
- A low-coordination Zn2+ solvation shell forms at the interface, enhancing stability during cycling.
- 1.5 Ah pouch cells with high coulombic efficiency over 500 cycles were achieved using this method.

## Abstract

This work introduces sulfated nanocellulose as an anion-rich additive to tailor the Zn anode interfacial solvation structure, reducing interfacial H2O activity and suppressing hydrogen evolution.In-situ attenuated total reflection Fourier transform infrared and fluorescence interface-extended X-ray absorption fine structure reveal the formation of a low-coordination Zn2+ solvation shell at the interface, facilitating rapid desolvation kinetics, enhancing interfacial stability during cycling.Practical aqueous Zn–MnO2 pouch cells (1.5 Ah), underscoring the potential of interfacial solvation engineering for high-performance aqueous zinc-ion batteries.

This work introduces sulfated nanocellulose as an anion-rich additive to tailor the Zn anode interfacial solvation structure, reducing interfacial H2O activity and suppressing hydrogen evolution.

In-situ attenuated total reflection Fourier transform infrared and fluorescence interface-extended X-ray absorption fine structure reveal the formation of a low-coordination Zn2+ solvation shell at the interface, facilitating rapid desolvation kinetics, enhancing interfacial stability during cycling.

Practical aqueous Zn–MnO2 pouch cells (1.5 Ah), underscoring the potential of interfacial solvation engineering for high-performance aqueous zinc-ion batteries.

The online version contains supplementary material available at 10.1007/s40820-025-01935-6.

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.

The online version contains supplementary material available at 10.1007/s40820-025-01935-6.