Boosting Ionic Conductivity in Zirconium-Based Oxychloride Solid Electrolytes via Br Doping for All-Solid-State Batteries

With the increasing demand for high-energy density and high-safety energy storage systems, all-solid-state batteries have emerged as a key development direction for next-generation lithium battery technology. Zirconium-based oxychloride solid electrolytes possess good compatibility with high-voltage cathodes and relatively low material cost. However, their ionic conductivity still requires further improvement. In this work, a series of Li3–xZrCl4O1.5–xBrx electrolytes were synthesized via a ball milling method. Br doping increases the concentration of Li+ vacancies and lowers the migration energy barrier while preserving the amorphous structure. When x = 0.025, the ionic conductivity reaches 3.4 mS cm–1 with an activation energy of 0.239 eV. An all-solid-state battery was assembled using a LiNi0.8Mn0.1Co0.1O2 cathode and a Li–In anode. The cell delivers a discharge capacity of 143 mAh g–1 after 200 cycles at 0.5 C with a coulombic efficiency of 99.9%, indicating excellent cycling stability.