Tailoring Molecular Competitive Adsorption for Stable Ah-Level Aqueous Zinc Metal Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• The water-dominated inner Helmholtz plane (IHP) at the electrode/electrolyte interface causes parasitic reactions and Zn dendrite growth, limiting aqueous zinc-metal batteries (AZMBs).
• Controlling interfacial water and ion deposition is crucial for AZMB performance.

Purpose of the Study:

• To develop a universal competitive adsorption strategy to reconstruct interfacial molecular distribution and induce orderly Zn2+ deposition in AZMBs.
• To improve the cycling stability and coulombic efficiency of AZMBs using DL-malic acid as an additive.

Main Methods:

• Introducing DL-malic acid (DL) as an additive to the Zn anode.
• Investigating the formation of a water-shielding IHP layer and its effect on Zn2+ deposition.
• Evaluating the performance of symmetric cells, Zn||Cu asymmetric cells, and Zn||I2 full cells with DL additive.

Main Results:

• DL molecules preferentially adsorb on the Zn anode, forming a water-shielding IHP layer that excludes water.
• Uniform Zn2+ deposition is achieved due to abundant active sites and homogenized Zn2+ flux from DL.
• Symmetric cells showed 8600 cycles stability; Zn||Cu cells achieved 99.9% coulombic efficiency over 3600 cycles.
• Zn||I2 full cells demonstrated stable operation for 4000 cycles, and pouch cells maintained capacity retention.

Conclusions:

• DL-malic acid is an effective additive for suppressing parasitic reactions and promoting uniform Zn2+ deposition in AZMBs.
• The competitive adsorption strategy successfully reconstructs the interfacial structure, enhancing battery performance and stability.
• This approach offers a promising pathway for the development of high-performance and long-lasting aqueous zinc-metal batteries.