A research group at Tohoku University has achieved a significant technological milestone in the field of next-generation energy storage. The team has developed a pioneering ultrasonic bonding method for oxide-based all-solid-state batteries. This technique allows for the formation of a stable interface between lithium metal and garnet-type solid electrolytes at room temperature in just a few seconds.
The primary challenge with garnet-type solid electrolytes, specifically lithium lanthanum zirconium oxide, has been the high interface resistance caused by insulating passive films on the lithium surface. Traditionally, overcoming this required energy-intensive high-temperature treatments or the hazardous use of molten lithium. The new method utilizes ultrasonic vibrations to effectively break down these insulating layers. Under applied pressure, the lithium metal undergoes plastic deformation, creating a dense and seamless contact with the lithium lanthanum zirconium oxide.
Initial results showed an interface resistance of approximately two hundred twenty-five ohms per square centimeter. However, by incorporating a thin intermediate metal layer, the researchers successfully reduced this resistance to a remarkable one point five ohms per square centimeter. This advancement significantly lowers the barriers to mass-producing all-solid-state batteries, which are safer and more energy-dense than current liquid-electrolyte versions. The research team plans to continue their work by analyzing the microscopic structures and the impact of surface roughness and grain boundaries to further optimize the bonding quality.
