Impact of Transport Properties at The Grain-Scale Engineering of Solid Electrolytes: Case Studies on Anti-Perovskite

Antiperovskites of composition M₃AB (M = Li, Na, K; A = O; B = Cl, Br, I, NO₂, etc.) have recently been investigated as solid-state electrolytes for all-solid-state batteries. Inspired by the impressive ionic conductivities of Li₃OC_l0.5Br_0.5 and Na₃OBH₄ as high as 10^-3 S/cm at room temperature, many variants of antiperovskite-based Li-ion and Na-ion conductors have been reported, and K-ion antiperovskites are emerging. These materials exhibit low melting points and thus have the advantage of easy processing into thin body and intimate contacts with electrodes. However, there are also issues in interpreting the stellar materials and reproducing their high ionic conductivities. We synthesized the antiperovskite materials by melt casting method and processed them through isostatic pressing (ISP) and conventional approaches. In this presentation, we discuss the critical role of isostatic pressing (ISP) on the crystal- and micro-structural features that originate the higher ionic conductivities of antiperovskites compared to conventional processing. We then discuss its impact on the electrochemical performance of the systems and scalable processing of solid-state battery (SSB) components, and their integration is a key bottleneck toward practical deployment. Finally, we also provide some key perspectives, challenges, and future directions for large-scale production of SSB components and integration.