A comprehensive exploration of Na+ ion transport in NaSICONs using molecular dynamics simulations

Abstract

Scandium-substituted Na_1+x+ySc_yZr_2−ySi_xP_3−xO₁₂ NaSICONs have emerged as promising electrolyte materials for all-solid-state sodium batteries. However, the comprehensive investigation of these multi-element structures is challenging due to their vast compositional space, leading to a limited number of compositions explored thus far. In this study, we address this issue by employing low-cost, yet high-precision force field molecular dynamics simulations based on density functional theory to investigate the Na⁺ mobility and resulting conductivity in Na_1+x+ySc_yZr_2−ySi_xP_3−xO₁₂ (0 ≤ x ≤ 3; 0 ≤ y ≤ 2). Our findings show that the incorporation of Sc³⁺- and Si⁴⁺-substituents enhances the conductivity, achieving values of 10⁻² S cm⁻¹ at room temperature for moderate to high substitution degrees. Moreover, our study demonstrates the efficacy of the applied methodology for large-scale screening, enabling the exploration of extensive configurational spaces of NaSICONs and other materials for potential use as solid-state electrolytes.