Invited: Solid-State Lithium Thin-Film Batteries Capable of Fast Charging

Abstract

Solid-state Li batteries are promising energy storage devices owing to their high-energy densities with improved safety. However, the large resistance at the interface of solid-electrolytes and electrodes hinders the fast charging and discharge of solid-state Li batteries. Accordingly, understanding electronic and ionic transport properties across interfaces is crucial for designing highperformance solid-state lithium batteries. Here, we introduced the semiconductor technology and their knowledge into battery research. The model solid-electrolyte/electrode interfaces were fabricated using epitaxial thin film growth techniques. We succeeded in demonstrating the interface resistance below 5 Ωcm2 (Li 3 PO 4 /LiCoO 2 interface [1], [2], Li 3 PO 4 /LiNi 0.5 Mn 1.5 O 4 interface [3]); the value is smaller than that of liquid-electrolyte-based Li-ion batteries. Furthermore, we found that the deteriorated interfaces improve by annealing the model interfaces. These studies strongly encourage solid-state Li battery research by demonstrating a very low interface resistance leading to fast charging and discharging.