Polyelectrolyte Complex Coating for Mitigating Decomposition at Argyrodite and Conductive Carbon Interfaces in...

Area of Science:

• Solid-state battery technology
• Electrochemical energy storage
• Materials science

Background:

• Sulfide-based solid electrolyte batteries (SEBs) offer high energy density for large-scale commercialization.
• Carbon additives like vapor-grown carbon fibers (VGCFs) are crucial for cathode utilization but can degrade sulfide electrolytes (e.g., Li6PS5Cl).
• Electrolyte decomposition at interfaces with cathode active materials and VGCFs limits cell capacity.

Purpose of the Study:

• To develop a protective coating for VGCFs to mitigate degradation in SEBs.
• To investigate the impact of a polyelectrolyte coating on VGCF interfaces within LiIn|LPSCl|LPSCl-NCM-VGCF (LiInSEBNCM) cells.
• To optimize coating thickness for improved cycling performance.

Main Methods:

• Application of a novel polyelectrolyte coating onto VGCFs.
• Evaluation of electrolyte oxidation at the VGCF interface using cyclic voltammetry.
• Assessment of cell performance through galvanostatic charge-discharge cycling.

Main Results:

• The polyelectrolyte coating effectively suppresses argyrodite oxidation at the VGCF|LPSCl interface.
• Coated VGCFs lead to improved cycling capacity in the LiInSEBNCM cells.
• An optimal polymer coating thickness was identified, balancing protection and VGCF aggregation for maximum performance.

Conclusions:

• Polyelectrolyte coatings on VGCFs are a viable strategy to enhance the stability and performance of sulfide-based solid-state batteries.
• Interface engineering is critical for overcoming degradation issues in high-energy-density solid-state batteries.
• Optimizing coating parameters is essential for maximizing the benefits of protective interlayers in SEBs.