Aliovalent substitution of Al3+ in Li2ZrCl6 solid electrolyte towards large-scale application

Halide solid electrolytes , known for their stability to 4 V-class cathodes and deformability, emerge as promising candidates for high-performance all-solid-state batteries. Unfortunately, their synthesis often involves expensive elements, limiting mass production and cost-effectiveness. In this study, aliovalent-substituted Li 2 ZrCl 6 with Al 3+ is fabricated by one-step ball milling , exhibiting lower cost, higher ionic conductivity and a wider electrochemical window. The cost is reduced by approximately 13.4 % through a 25 % aliovalent substitution. Li + conductivity of Li 2+x Zr 1-x Al x Cl 6 increases from 0.12 mS/cm ( x = 0) to a peak of 1.13 mS/cm ( x = 0.25) at 25 °C, and activation energy (Ea) reduces from 0.43 eV to 0.29 eV, which is attributed to the extension of Li + migration pathways along intra- and inter- ab-plane around Al sites as revealed by AIMD and BVSE calculations. Both experimental result and calculation indicate that the substitution of Al 3+ improves the oxidation potential from 4.1 V in Li 2 ZrCl 6 to 4.3 V in Li 2.25 Zr 0.75 Al 0.25 Cl 6 . Furthermore, the excellent electrochemical performance of all-solid-state batteries is demonstrated using Al 3+ -substituted Li 2 ZrCl 6 and commercial LiNi 0.8 Co 0.1 Mn 0.1 O 2 . The unravelled multifaceted effects of Al 3+ aliovalent substitution in Li 2 ZrCl 6 solid electrolyte endow it highly advantageous for future applications in halide-based all-solid-state lithium batteries.