Dual-Binder-Enabled 18-µm-Thick High-Conductivity Sulfide Electrolyte Film for High-Energy-Density All-Solid-State...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• High-energy-density all-solid-state batteries (ASSBs) require ultrathin, high ionic conductivity sulfide solid-state electrolytes (SSEs).
• Conventional binders hinder Li-ion transport kinetics in SSE films, and transport mechanisms are not fully understood.

Purpose of the Study:

• To develop an ultrathin SSE film with enhanced ionic conductivity and understand Li-ion transport mechanisms.
• To improve interfacial compatibility and kinetic stability in ASSBs.

Main Methods:

• Fabrication of an ultrathin SSE film (USF) using a Li-ion-conductive polymer binder (LiTFSI-PMEMA) and SSEs via dry processing.
• Characterization using cryogenic transmission electron microscopy (cryo-TEM), solid-state nuclear magnetic resonance (ssNMR), and theoretical simulations.
• Implementation in ASSBs and pouch cells for performance evaluation.

Main Results:

• A 18 µm thick USF with high ionic conductivity (1.56 mS cm⁻¹).
• A proposed Li+ transport model involving SSE, polymer binder, and interface regions.
• Exceptional interfacial compatibility and kinetic stability, achieving 70.3% capacity retention over 1500 cycles in ASSBs.
• A pouch cell delivering a high stack-level energy density of 322.7 Wh kg⁻¹.

Conclusions:

• The study provides crucial insights into multiphase Li-ion transport kinetics in SSE films.
• Demonstrates a scalable manufacturing strategy for sulfide-based ASSBs using conductive polymer binders.
• Highlights the potential of the developed USF for next-generation high-energy-density batteries.