Ethylene Glycol-Choline Chloride Based Hydrated Deep Eutectic Electrolytes Enabled High-Performance Zinc-Ion Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous rechargeable zinc-ion batteries (ARZIBs) offer a safe and cost-effective energy storage solution.
• Challenges in ARZIBs include electrode stability and electrolyte performance.
• Developing advanced electrolytes and electrode materials is crucial for ARZIB development.

Purpose of the Study:

• To develop novel hydrated deep-eutectic electrolytes (HDEEs) for ARZIBs.
• To synthesize and investigate a V10O24·nH2O@rGO composite cathode material.
• To evaluate the electrochemical performance of the HDEE and cathode combination in ARZIBs.

Main Methods:

• Formulation and characterization of ethylene glycol-choline chloride (Eg-ChCl) based HDEEs.
• Synthesis of a V10O24·nH2O@rGO composite cathode.
• Electrochemical testing including cycling, rate capability, and stability studies.
• Fabrication and testing of a flexible pouch-cell prototype.

Main Results:

• The optimized 1-0.5-4-2 HDEE exhibited low viscosity, high Zn2+ conductivity (20.38 mS cm-1), and a high Zn transference number (0.937).
• The HDEE demonstrated a wide electrochemical stability window (>3.2 V) and enabled dendrite-free Zn stripping/plating for over 1000 hours.
• The ZnǁV10O24·nH2O@rGO//HDEE cell achieved a high reversible capacity (≈365 mAh g-1), excellent rate performance, and remarkable cycling stability (≈63.10% retention after 4000 cycles at 10 A g-1).
• The system showed stable performance across a wide temperature range (0-80 °C).

Conclusions:

• The developed HDEEs and V10O24·nH2O@rGO composite offer a promising approach for high-performance and safe ARZIBs.
• The optimized electrolyte composition significantly enhances Zn ion transport and electrode stability.
• The flexible pouch-cell prototype demonstrates the practical potential of this technology for various applications.