Lithium ion batteries are considered as a promising candidate for electric vehicles and other similar demanding applications. Electrolyte is one of the main components of a rechargeable battery and safety of a battery largely depends on it. Various types of liquid electrolytes were developed over time to enhance the performance of the battery. However, liquid electrolytes promote the growth and formation of lithium dendrites, which cause short circuit in the battery which eventually leads to fire hazard. Solid state electrolyte was found to be a better alternative, because it suppresses the growth and formation of the lithium dendrites between the electrodes. Garnet-type Li₇La₃Zr₂O₁₂ (LLZO) has been considered as a promising candidate for next-generation solid-state electrolyte in lithium batteries because it possesses high ionic conductivity, wider electrochemical and thermal stability window.

This is the first report of doping LLZO by eutectic Al-Si alloy. Al-Si alloy is added because Al is considered as a cubic phase stabilizer and Si helps in modifying the path of lithium ions in LLZO. Further, lithium based solid state batteries are fabricated by using lithium foil anode, LLZO based electrolyte and LiFePO₄ cathode material. The doped Ai-Si LLZO solid electrolyte showed better electrochemical performance over the bare LLZO solid electrolyte. Thus, the Al-Si doped LLZO could be a candidate material for solid electrolyte for next generation all solid state lithium batteries.