With the conventional liquid electr

With the conventional liquid electrolytes being replaced by inorganic solid electrolytes, the long-standing safety issues in Li batteries could be greatly alleviated, and the energy density may also be further increased due to the broader electrochemical window [1-3]. Among the extensively studied inorganic solid electrolytes, oxides possess several attractive characteristics that are absent in sulfides [4-6]. For example, they are generally much more stable in ambient air, and the compatibility with high-potential cathodes are also a lot better [4-6]. Regardless, unlike the easily deformable sulfides, oxides are typically brittle; simply pressing the powder together only leads to very poor particle-particle contact and cannot generate macroscopically meaningful conductivity [7]. As such, sintering is needed to densify the ceramic. However, the high temperatures involved in this process create a grand challenge for solid-electrolyte fabrication.