Electrolyte breakthrough could help make next-gen solid-state batteries

Researchers at Japan’s Tohoku University have demonstrated that two pressure-assisted sintering methods—hot pressing (HP) and spark plasma sintering (SPS)—are equally effective for fabricating dense, high-quality garnet-type oxide solid electrolytes (Li₇La₃Zr₂O₁₂ or LLZO) for next-generation solid-state lithium metal batteries (SSLMBs). Both techniques achieve nearly full densification (~98%) in under five minutes without significant differences in ionic conductivity or microstructure. This challenges the previously held belief that SPS offers unique advantages due to a “plasma effect,” showing instead that densification is driven primarily by applied pressure and heat. The study, published in Small, highlights that either HP or SPS can be chosen based on factors such as cost, equipment availability, and scalability rather than presumed performance superiority. This finding is significant because conventional oxide electrolyte fabrication requires prolonged high-temperature sintering, which is costly and leads to lithium evaporation. By validating these rapid