Garnet related lithium ion conductor processed by spark plasma sintering for all solid state batteries

Oxide-based all solid state battery (ASSB) systems require highly enhanced cell assemblies technology in the light of the sintering issue, although various inorganic-based lithium ion conductors have been proposed and attempted to be adopted in battery systems. Here, the compatibility of Li-La-(Zr-Ta)-O garnet related lithium ion conductors with ASSB systems processed by spark plasma sintering (SPS) is reported. Further, the challenges with respect to the material and processing are also discussed. Li7−xLa3Zr1.5Ta0.5O12−d processed by SPS shows a high ionic conductivity of 1.35 × 10−3 S cm−1 and 1.23 × 10−2 S cm−1 at 25 °C and 80 °C, respectively. In addition, the material also shows good structural stability, which is a critical challenge encountered in garnet structured materials treated under severe SPS process conditions. An ASSB assembled by SPS using the Li4Ti5O12-Li7−xLa3Zr1.5Ta0.5O12−d composite electrode shows a surface capacity of 0.2 mAh cm−2 at 80 °C. The battery shows a well-organized structure with a good lithium diffusion percolation path and the low solid contact resistance without any defects and undesirable reactions arising from the sintering method.