Scavenging Meets Reinforcement: A Dual-Functional Electrolyte Additive Approach to Dendrite-Free Lithium-Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-metal solid-state batteries (ASSBs) face challenges with stable low-pressure operation due to poor interfacial contact and lithium dendrite growth.
• Achieving reliable performance in ASSBs is crucial for next-generation energy storage solutions.

Purpose of the Study:

• To develop a dual-functional additive strategy for sulfide-based solid electrolytes (SEs) to improve interfacial stability and enable low-pressure operation in Li-metal ASSBs.
• To address the limitations of current ASSB technology by enhancing mechanical robustness and electrochemical performance.

Main Methods:

• Incorporation of mechanically robust and lithium-scavenging Li4Ti5O12 (LTO) particles into sulfide-based SEs via powder mixing and cold pressing.
• Careful control of LTO particle size to localize them at grain boundaries and pores without hindering Li-ion conduction.
• Fabrication of LTO-incorporated composite solid electrolytes (LTO-CSE) and testing in custom-built spring-loaded cells.

Main Results:

• The LTO-CSE demonstrated enhanced mechanical reinforcement and electrochemical scavenging, improving current homogenization through zero-strain lithiation.
• Significantly improved stability at high current densities and low stack pressures (down to 2 MPa) was observed.
• The critical current density was raised from 4.5 to 7.5 mA cm⁻² at 10 MPa, and full cells achieved over 900 stable cycles with a high areal capacity of ≈3.5 mAh cm⁻².

Conclusions:

• The developed LTO-CSE offers a scalable approach to overcome key challenges in Li-metal ASSBs, particularly concerning low-pressure operation and dendrite suppression.
• This work establishes a generalizable design framework for creating robust and high-performance solid electrolytes for advanced solid-state batteries.
• The findings suggest a promising pathway for the commercialization of safer and more efficient ASSBs.