A Superior Li ₂ CO ₃ -Derived Li ₂ ZrOCl ₄ Electrolyte Enabling High-Performance All-Solid-State Lithium Batteries

All-solid-state lithium batteries (ASSLBs) are promising next-generation energy storage systems due to their superior safety. While low-cost Li2ZrCl6 is a candidate halide solid electrolyte, its ionic conductivity remains modest (0.33 mS cm–1). Herein, we report a highly conductive amorphous halide solid electrolyte (1.64 mS cm–1), synthesized using high-energy Li2CO3 as a precursor to replace conventional Li2O. This approach enhances reaction efficiency and reduces cost. The resulting Li2ZrOCl4 (LZOC) structure facilitates Li+ migration, as confirmed by experimental and theoretical results. ASSLBs incorporating the LZOC electrolyte with a Li–In anode and uncoated LiCoO2 (LCO) cathode demonstrate excellent cycling stability (97% capacity retention after 200 cycles at 1 C) and high-rate capability (over 70 mAh g–1 at 2 C). This work establishes the use of low-cost Li2CO3 as a practical strategy for developing high-performance, cost-effective ASSLBs.