Robust I···H-O Intramolecular Halogen Bond Boosts Reversible I₃^-/I^- Redox Behavior for Sustainable Potassium-Iodine...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Potassium-iodine batteries offer high power and sustainability but face challenges with polyiodide dissolution and complex electrode fabrication.
• These issues limit performance and hinder widespread adoption of this promising battery technology.

Purpose of the Study:

• To develop a scalable and cost-effective electrode material for high-performance potassium-iodine batteries.
• To address polyiodide dissolution and simplify electrode production for improved energy storage solutions.

Main Methods:

• A "solution-adsorption" strategy was employed for scale-up production of Ti3C2(OH)x-wrapped carbon nanotube paper (CNP).
• Characterization and theoretical calculations were used to understand the interaction between CNP and the iodine redox couple.
• A 100 mAh pouch cell was fabricated using the developed electrode.

Main Results:

• CNP demonstrated strong affinity for the I3-/I- redox couple, with Ti-OH groups on MXene forming stable intramolecular halogen bonds to prevent polyiodide dissolution.
• The free-standing electrode facilitated reversible redox chemistry, leading to high-performing potassium-iodine batteries.
• The fabricated pouch cell achieved a high energy density of 130 Wh kg-1 with a 10-minute charge/discharge cycle, outperforming existing battery systems.

Conclusions:

• The synergistic effect between CNP and MXene enables a simple, scalable electrode fabrication for high-performance potassium-iodine batteries.
• This cost-effective potassium-iodine battery technology (US$255 kWh-1) presents a sustainable alternative for grid-scale energy storage.
• The developed battery system offers a competitive combination of high energy and power density.