A percent-level amide additive for stable aqueous zinc-ion batteries

Abstract

The Zn anode/electrolyte interface faces critical challenges, including hydrogen evolution reaction, corrosion, and dendrite growth that degrade battery performance. This study employs 1 mol% N-(2-hydroxyethyl) succinimide (NHS) as a multifunctional electrolyte additive to address these issues. The carbonyl groups (C=O) in NHS can strongly coordinate with Zn atoms and water molecules, selectively adhering to the Zn anode surface to displace H₂O, thereby suppressing parasitic reactions while simultaneously reducing water activity in the electrolyte. The NHS can regulate Zn²⁺ solvation by replacing water molecules in the primary solvation sheath, thereby further facilitating Zn²⁺ desolvation by reducing the number of bound water molecules. Additionally, the NHS on the anode surface enables a homogeneous Zn²⁺ flux, resulting in uniform zinc deposition. As a result, the NHS enables a ZnZn symmetric cell to achieve 7,500 h cycling at 1 mA·cm⁻², and a ZnCu cell to maintain 99.8% Coulombic efficiency over 3200 cycles. The ZnV₂O₅ full cell retains 82.5% capacity after 7,000 cycles. These findings highlight the proficiency of the NHS in securing Zn anodes for enhanced battery performance.