Self-Derived Stress-Release Phase Enables High-Performance Self-Healing Sodium Anodes

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Self-healing anodes in alkali-ion batteries are crucial for long-term stability.
• The precise mechanism of self-healing, especially concerning stress evolution, requires further elucidation.
• Liquid metals offer unique properties for developing self-healing electrode materials.

Purpose of the Study:

• To investigate the self-healing mechanism in liquid metal-enabled anodes from a stress evolution perspective.
• To demonstrate a self-derived stress-release phase strategy for enhanced sodium storage.
• To evaluate the electrochemical performance of gallium selenide (Ga2Se3) as a self-healing anode material.

Main Methods:

• Theoretical calculations to understand the role of liquid gallium (Ga).
• In situ X-ray diffraction (XRD) analysis to observe structural changes during cycling.
• Electrochemical performance testing in half and full sodium-ion battery cells.

Main Results:

• Liquid Ga was successfully self-derived during the conversion reaction in Ga2Se3.
• A unit-cell 'breathing' mechanism induced by liquid Ga was identified as the stress-release phase.
• Ga2Se3 anodes exhibited excellent cycling performance (≈200 mAh g⁻¹ at 10 A g⁻¹) and capacity retention (91.5% after 150 cycles).

Conclusions:

• Self-derived stress-release phases are key to achieving self-healing behavior in electrodes.
• The liquid Ga in Ga2Se3 effectively heals cracks and alleviates strain, ensuring long-term stability.
• This strategy offers a new paradigm for designing high-performance sodium-ion battery anodes.