A new class of carbonate–oxychloride solid electrolytes for high-performance sodium-ion all-solid-state batteries

Novel Na-ion solid-state electrolytes (MCl y – x Na 2 CO 3 , M = Ta, Nb, Hf, Zr, and Al) were synthesized rapidly by ball milling. Conductivity of 1.11 mS cm −1 was achieved in 10 min for TaCl 5 –1.2Na 2 CO 3 , with optimized TaCl 5 –0.5Na 2 CO 3 reaching 5.01 mS cm −1 .