"Solid-in-Solid" Electrolyte via Scalable Melting Infiltration Method for High-Voltage Solid-State Lithium Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Solid electrolytes are crucial for safe, high-energy-density batteries but face challenges in electrochemical stability, interfacial contact, and manufacturing.
• Current solid-state battery (SSB) technologies are limited by electrolyte performance and scalable production methods.

Purpose of the Study:

• To develop a novel solid-in-solid electrolyte architecture for improved SSB performance and manufacturability.
• To investigate the ionic transport mechanisms and electrochemical properties of the new electrolyte system.
• To demonstrate the potential of the developed electrolyte for practical, high-power SSB applications.

Main Methods:

• Fabrication of a "solid-in-solid" electrolyte by infiltrating a porous lithium zeolite (LiX) with a melt-processable plastic crystal electrolyte (PCE).
• Characterization of ionic conductivity (0.55 mS/cm at 20 °C) and electrochemical stability.
• Solid-state nuclear magnetic resonance (NMR) spectroscopy to elucidate Li+ transport pathways.
• Development of a roll-to-roll-compatible melt infiltration strategy for scalable SSB fabrication.
• Performance testing of SSBs including rate capability, cycling stability, and voltage compatibility.

Main Results:

• The LiX-PCE electrolyte exhibits enhanced electrochemical stability compared to pure PCE.
• Three distinct Li+ transport pathways were identified: within LiX, within PCE, and at phase boundaries.
• Scalable roll-to-roll fabrication of SSBs using melt infiltration was demonstrated.
• Achieved excellent rate performance (up to 10 C), 93% capacity retention after 200 cycles at 2C, and 4.5 V compatibility.

Conclusions:

• The "solid-in-solid" LiX-PCE electrolyte offers a promising solution for overcoming limitations in current solid-state battery technology.
• The melt-processability and identified transport mechanisms provide critical design principles for high-performance solid-state electrolytes.
• This work presents a viable pathway toward practical, fast-charging, high-power solid-state batteries.