Molecular Evolution of Target Organosulfur Enables High-Performance Aqueous Zinc Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Organic cathode materials are promising for aqueous zinc-ion batteries (AZIBs) due to sustainability and tunability.
• Key challenges include low voltage, slow kinetics, and high solubility of n-type materials, limiting their practical use.

Purpose of the Study:

• To address limitations of current organic cathode materials for AZIBs.
• To develop a high-performance, stable, and cost-effective organic cathode material through molecular evolution.

Main Methods:

• Molecular evolution and rational selection of organodisulfide 2,2 -dithiobis(benzothiazole) (MBTS) as an n-type cathode material.
• Utilized density functional theory (DFT) calculations to understand reaction mechanisms and synergistic effects.
• Fabricated and tested pouch cells with MBTS electrodes under various conditions, including high mass loading.

Main Results:

• MBTS exhibits a reduced sulfur-sulfur bond dissociation energy due to N-containing benzothiazole rings, enhancing discharge voltage (1.02 V) and kinetics.
• Achieved a high specific capacity of 153.6 mAh g^-1 at 0.05 A g^-1 with low overpotential (100 mV).
• Demonstrated excellent rate capability (124.4 mAh g^-1 at 1 A g^-1), stable cycling (96.8% retention over 200 cycles), and high performance under ultrahigh mass loading (18.2 mg cm^-2).

Conclusions:

• MBTS is a highly effective n-type cathode material for AZIBs, overcoming common limitations.
• The molecular design strategy and DFT insights provide a pathway for developing advanced organic electrode materials.
• The material's performance under high mass loading suggests significant potential for practical AZIB applications.