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 x 10(-3) S cm(-1) and 1.23 x 10(-2) S cm(-1) at 25 degrees C and 80 degrees 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 degrees 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. (C) 2013 Elsevier B.V. All rights reserved.