Abstract:

Sulfide based all solid state lithium batteries (ASSLBs) have attracted widespread interest in the industry due to their potential to address the limited energy density and safety concerns of conventional Li-ion batteries,while benefiting from the high ionic conductivity (10^-3—10^-2 S/cm) and ductility of sulfide solid electrolytes(SEs). However, the production of thick electrolyte membranes to obtain enough mechanical strength, and the preparation of sulfide materials and positive electrode composite membranes to reduce interface impedance, resulted in a lower energy density in ASSLBs compared to their theoretical energy density. From this, it can be seen that sulfide solid electrolyte membranes are crucial for the performance of ASSLBs, and the fabrication of ultra-thin and strong sulfide-based solid electrolyte (SSEs) membranes stands as a critical solution to this challenge. This paper begins with a concise analysis of the criteria and preparation challenges for thin SSEs membranes through a review of recent literature. It then systematically summarizes existing preparation techniques, detailing the advantages and limitations of each method. These techniques are broadly categorized into wet-process (e.g., cold/hot pressing, tape casting, infiltration, 3D printing and et al) and dry-process approaches (e.g., powder compaction and binder fibrillation). Notably, tape casting and infiltration methods demonstrate potential for large-scale fabrication and compatibility with conventional liquid lithium-ion battery electrode production lines. Binder fibrillation, being solvent-free, significantly reduces environmental impact and manufacturing costs. Finally, the paper outlines future development directions for thin SSEs membranes.

Key words: sulfide-based solid electrolyte membranes, wet-process, slurry, binder, solvent-free