Selective Confinement by a COF-Derived Sub-Nanoporous Interface for High-Performance CoF₂ Thermal Battery Cathodes.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Transition metal fluoride (TMF) cathodes suffer from dissolution issues in Li+-conducting systems, limiting their use in high-voltage thermal batteries.
• This dissolution leads to performance degradation and reduced cycle life, hindering the development of advanced energy storage.

Purpose of the Study:

• To address the dissolution barrier of TMF cathodes by developing a selective confinement strategy.
• To enable high-voltage thermal batteries with improved stability and energy density.

Main Methods:

• Constructed a sub-nanoporous carbon interface in situ on CoF2 particles using a covalent organic framework (COF).
• Engineered the interface with 0.54 nm pores to selectively confine dissolved species while allowing Li+ ion transport.
• Investigated the mechanism of ion confinement and its effect on battery performance.

Main Results:

• The engineered interface effectively suppressed the cathode shuttling effect by confining dissolved CoCl42- ions.
• The modified CoF2 cathode achieved a high discharge plateau (>2.5 V), specific capacity (365 mAh g-1), and specific energy (882 Wh kg-1).
• Demonstrated a high-performance thermal battery operating at 100 mA cm-2.

Conclusions:

• The developed ion-sieving carbon interface is a general and effective strategy for stabilizing TMF cathodes.
• This approach unlocks the potential of metal fluoride cathodes for advanced energy storage applications.
• The study provides a pathway for designing robust and high-performance batteries.