Fast ionic conductivity by thermal treatment with ultralow electronic transport in solid-state electrolyte Na3YCl6

Improving the ionic and electronic conductivities of solid-state electrolytes (SSEs) is urgently needed to develop commercially viable all-solid-state batteries. Here, we provide atomistic insights into the electronic transport properties and Na ionic conductivity of the halide-based SSE Na3YCl6 (NYC) with a trigonal structure and propose a way for improving ionic conductivity by amorphization. Our ab initio calculations, employing a highly accurate hybrid functional and many-body method, reveal high electric and thermal insulating behavior of crystalline NYC. Using machine learning interatomic potential-based molecular dynamics simulations, we demonstrate low ionic conductivity at room temperature in the crystalline phase, but a significantly higher value of 0.29 mS/cm in amorphous NYC simulated by thermal treatment, highlighting that amorphization is an effective way for improving ionic conductivity.