An ultrafast process for the fabrication of a Li metal–inorganic solid electrolyte interface

A lithium anode is expected to be applied to next-generation batteries using inorganic solid electrolytes (ISEs). When joining Li with ISEs, interfacial reactions often cause performance degradation and have been avoided. In this report, we demonstrate a new strategy for the ultrafast formation of a good interface between Li and ISEs, using a reactive process (ultrasonic-assisted fusion welding method). We found that ultrasonic irradiation helps in suitable interface formation between molten Li and ISEs, and the joining process finishes in just a few seconds. The obtained interface showed a low resistance and could be used under a high current density of 0.5 mA cm−2. The development of prototype cells for next-generation batteries was promoted by this ultrafast process.