Overcoming the conversion reaction limitation at three-phase interfaces using mixed conductors towards energy-dense...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) all-solid-state batteries (ASSBs) offer potential for safe, high-energy-density storage.
• Current Li-S ASSBs face challenges with sluggish sulfur conversion kinetics and limited sulfur utilization due to restricted three-phase boundaries.

Purpose of the Study:

• To overcome kinetic limitations in Li-S ASSBs by enhancing sulfur conversion reactions.
• To improve active sulfur utilization and overall battery performance in Li-S ASSBs.

Main Methods:

• Development and implementation of mixed ionic-electronic conductors (MIECs) within sulfur cathodes.
• Utilizing advanced microscopic and tomographic analyses to study reaction interfaces and material conversion.
• Investigating the impact of MIECs on sulfur conversion at sulfur-MIEC interfaces.

Main Results:

• MIECs promote conversion reactions at sulfur-MIEC interfaces, complementing traditional three-phase boundaries.
• Emergence of mixed-conducting domains at sulfur-MIEC boundaries facilitates thorough conversion of sulfur to Li₂S.
• Achieved high active sulfur ratios (up to 87.3%) and conversion degrees (>94%) in Li-S ASSBs.
• Demonstrated high discharge capacity (>1,450 mAh g⁻¹) and long cycle life (>1,000 cycles).

Conclusions:

• The integration of MIECs effectively enhances sulfur conversion and active material utilization in Li-S ASSBs.
• This strategy offers a promising pathway for developing next-generation safe and energy-dense battery technologies.
• The approach is applicable to improving other conversion cathode materials.