CHAPTER 3: Electrolyte Development for Solid-state Lithium Batteries

In this chapter, we report on the recent progress in the development of Li-ion electrolytes for next- generation Li batteries. With a brief overview of state-of-the-art organic polymer electrolytes for Li-ion batteries, the status of solid-state (ceramic) Li-ion electrolyte research based on various inorganic compounds including Li₃N, Li-β-alumina, Li₃PO₄, Li₄SiO₄, Li-based sodium super ionic conductors (NASICON) structure, LiM₂(PO₄)₃ (M = Zr, Ti, Ge), lithium super ionic conductor (LISICON) Li₁₄Zn(GeO₄), perovskite-type La_(2/3)−xLi_3xTiO₃ (LLTO), anti-perovskite Li₃OX (X = Cl, Br) and garnet-type structure Li₅La₃M₂O₁₂ (M = Nb, Ta, Sb), Li₆La₂AM₂O₁₂ (A = Ca, Sr, Ba; M = Nb, Ta), and Li₇La₃M₂O₁₂ (M = Zr, Hf) are reviewed. Among these solid Li-ion electrolytes, some of the Zr and Ta-based Li-stuffed garnet-type oxides such as Li₅La₃Ta₂O₁₂, Li₇La₃Zr₂O₁₂ and Li_7−xLa₃Zr_2−xTa_xO₁₂, and Li_4−xSi_1−xP_xO₄ membranes were found to be stable against chemical reaction with elemental Li and electrochemically stable at high voltages, which may enable high energy density Li-ion batteries. Application of selected solid-state Li-ion electrolytes in all-solid-state Li-ion batteries is presented in this chapter.