An efficient all-solid-state battery (ASSB) was designed using a hybrid system composed of a thin film solid electrolyte and a thick composite electrode fabricated by spark plasma sintering (SPS). The optimized parameters for preparing the composite electrode were identified, including the optimal SPS conditions to inhibit decomposition of the active material and the most suitable composite electrode formulation (active material/solid electrolyte/electrical conductor ratios) to ensure good ionic and electronic percolation. The composite electrode fabricated by SPS exhibited good mechanical properties. The all-solid-state battery fabricated using the thin and thick film process displayed a maximum surface capacity of 0.30 mAh cm−3 at 80 °C. The battery also showed good stability of the interfacial contact between the composite electrode and thin film solid electrolyte. Furthermore, no diffusion of solid electrolyte materials from the composite electrode to the thin film electrolyte was observed after several cycles.