Confining Conversion Chemistry in Intercalation Host for Aqueous Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conversion-type anode materials are crucial for high-capacity aqueous rechargeable batteries (ARBs).
• Existing materials suffer from poor cycling stability and slow reaction kinetics, limiting their practical application.
• Confining conversion reactions within an intercalation host offers a potential solution to these challenges.

Purpose of the Study:

• To develop a novel anode material that overcomes the limitations of current conversion-type anodes in ARBs.
• To demonstrate the effectiveness of confining conversion chemistry within an intercalation host structure.
• To explore the potential of this new material for next-generation energy storage devices.

Main Methods:

• Synthesis of an integrated layered anode material, iron oxide hydroxide-pillared titanate (FeNTO), using sodium titanates as a model intercalation host.
• Characterization of the FeNTO material's structure and electrochemical performance.
• Testing of FeNTO in various aqueous electrolytes and fabrication of quasi-solid-state ARB pouch cells.

Main Results:

• The FeNTO material exhibits spatially and kinetically confined conversion reactions within its sub-nano interlayer.
• Achieved significantly reduced redox polarization (4-6 times lower), an ultralong lifespan (up to 8700 cycles), and excellent rate performance.
• Demonstrated universal cation intercalation for charge compensation, enabling operation in diverse aqueous electrolytes (Li+, Na+, K+, Mg2+, Ca2+, etc.).
• Successful large-scale synthesis of FeNTO thin film and powder, and fabrication of high-voltage ARB pouch cells.

Conclusions:

• Confining conversion chemistry within an intercalation host is a powerful strategy to enhance anode material performance for ARBs.
• FeNTO represents a disruptive electrode material with potential for advanced energy storage applications.
• The developed material and cell design enable robust ARBs for wearable electronics, even under extreme mechanical stress.