Highly efficient ion-transport "polymer-in-ceramic" electrolytes boost stable all-solid-state Li metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Polymer-in-ceramic (PIC) electrolytes offer thermal and mechanical advantages for all-solid-state batteries (ASSBs).
• Challenges remain in achieving fast lithium-ion transport and uniform Li+ deposition in PIC electrolytes.
• The influence of ceramic particle size on Li+ transport and anode compatibility is not well understood.

Purpose of the Study:

• To optimize ceramic particle size in PIC electrolytes for balanced ionic conductivity and anode compatibility.
• To investigate the effect of ceramic particle size on lithium-ion transport mechanisms.
• To enhance the performance of all-solid-state batteries through optimized PIC electrolytes.

Main Methods:

• Preparation and characterization of PIC electrolytes with varying ceramic particle sizes.
• Electrochemical impedance spectroscopy to measure ionic conductivity.
• Li/PIC/Li symmetric cell cycling to evaluate Li+ deposition and stability.
• Assembly and testing of Li/PIC/LiFePO4 cells to assess battery performance.

Main Results:

• An optimized ceramic particle size of 17 μm was identified, balancing interfacial impedance and surface roughness.
• The 17 μm PIC electrolyte exhibited enhanced Li+ conductivity (4.11 × 10^-4 S cm^-1 at 60°C) and a high transference number (0.74).
• Li/PIC/Li symmetric cells demonstrated stable cycling for 2800 hours, and Li/PIC/LiFePO4 cells showed excellent capacity retention (93.28% after 100 cycles).

Conclusions:

• Moderate ceramic particle size is crucial for optimizing Li+ flux and conductivity in PIC electrolytes.
• The optimized 17 μm PIC electrolyte significantly improves ionic conductivity and lithium anode compatibility.
• This study provides a pathway for developing high-performance and stable all-solid-state batteries using tailored PIC electrolytes.