Li⁺ Conduction Mechanism in Anion-Substituted Halide Solid Electrolytes for All-Solid-State Batteries

The recent emergence of halide superionic conductors, such as Li₃YCl₆, as solid electrolyte (SE) materials for all-solid-state batteries (ASSBs) is considered a game changer. These halide SEs offer a combination of advantageous properties that include excellent (electro)chemical oxidative stability, high Li⁺ conductivity, and mechanical deformability. This unique combination of properties position halide SEs as promising candidates for the development of next-generation ASSBs, surpassing the limitations of sulfide or oxide SEs.<br/>However, despite these benefits, the practical deployment of these materials has been hindered by the high cost associated with the use of expensive or rare transition metals. To overcome this, a cost-effective and abundant Zr-based compound Li₂ZrCl₆ has emerged. Yet, there remains a need to improve Li⁺ conductivity further and develop a more comprehensive understanding of the underlying ion conduction mechanisms.<br/>This presentation delves into the impact of anion substitution on changes in the local structure and ion conductivity of halide SE, offering an in-depth explanation of the ion conductivity mechanism. Particularly, we present noteworthy findings that demonstrate nearly twofold enhancements in ion conductivity upon anion-substitution of halide superionic conductors. Furthermore, we also investigate the feasibility of these materials in ASSB cells.<br/><br/>References<br/>[1] <i>Adv. Energy Mater. </i><b>2021</b>, <i>11</i>, 2003190. <br/>[2] <i>ACS Energy Lett. </i><b>2022</b>, <i>7</i>, 1776.<br/>[3] <i>Nat. Commun</i>. <b>2023</b>, <i>14</i>, 2459.