Supramolecular Interface Buffer Layer for Stable Zinc Anode.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc ion batteries (AZIBs) face challenges like side reactions and uneven zinc plating.
• Controlling water activity and Zn²⁺ dynamics at the anode/electrolyte interface is crucial for AZIB performance.
• Existing methods struggle to effectively mitigate these interfacial issues.

Purpose of the Study:

• To investigate the use of (2-hydroxypropyl)-β-cyclodextrin (HBCD) as an electrolyte additive in AZIBs.
• To demonstrate how HBCD can create a supermolecule interface buffer layer to manage water and Zn²⁺.
• To enhance the stability and cycle life of AZIBs through improved anode/electrolyte interactions.

Main Methods:

• Utilizing (2-hydroxypropyl)-β-cyclodextrin (HBCD) as an electrolyte additive.
• Employing HBCD to form a protective layer on the zinc anode, screening active water molecules.
• Modulating Zn²⁺ ion transport and nucleation to achieve preferred crystal orientation.

Main Results:

• HBCD effectively adsorbs onto the anode, repelling active water and disrupting hydrogen bonds.
• A (002)-preferred zinc crystal texture was achieved, promoting uniform plating.
• Symmetric Zn//Zn batteries showed extended lifespan (350 h at 10 mA cm⁻²/10 mAh cm⁻²) and high Depth of Discharge (73.26%).
• Zn//NVO batteries achieved a high discharge capacity of 380.4 mAh g⁻¹ at 1 A g⁻¹.
• A full battery with a low N/P ratio (2.16) demonstrated stable cycling over 500 cycles with ≈260 mAh g⁻¹ capacity.

Conclusions:

• HBCD acts as an effective supermolecule interface buffer, significantly improving AZIB performance.
• The strategy of regulating water activity and Zn²⁺ dynamics with HBCD addresses key interfacial challenges.
• This approach offers a promising pathway for developing stable and high-performance aqueous zinc ion batteries.