Super Ionic Li3-2xMx(OH)1-yNyCl (M=Ca, W, N=F) Halide Hydroxide as an Anti-Perovskite Electrolyte for Solid-State Batteries

Lithium halide hydroxide (Li 2 OHX) as a new class of low-cost, lightweight solid electrolyte (SSE) shows promising lithium-ion conductivity for advanced solid-state batteries. Here, using solid-state synthesis and extensive materials characterization, the impurity-free Li 3–2x M x (OH) 1-y N y Cl (M=Ca, W, N=F) are reported, having σ gb = 23.7 mS cm −1 and σ b = 9.6 mS cm −1 at 140 °C for x = y = 0 . Substituted smaller anionic dopants, such as F − , facilitate the movement of Li ions within the anti-perovskite framework through rotational disordering in local coordination, resulting in the highest ion conductivity of 0.28 mS cm −1 at 25 °C. Using a strong combination of XRD, FTIR, pH, elemental EDS analysis, and calculated activation energies, it is demonstrated that the presence of H in these SSEs yields significantly higher Li + -ionic conductivity. Rotation of an OH-group in enlarged Cl-O-Cl triangular in the synthesized SSEs and their fully defected/ disordered structures enhance Li-ion conductivity.