Direct calculation of effective mobile ion concentration in lithium superionic conductors
Bowei Pu, Zheyi Zou, Jinping Liu, Bing He, Dezhi Chen, Da Wang, Yue Liu, Maxim Avdeev, Siqi Shi
Abstract
In the realm of lithium superionic conductors, pursuing higher ionic conductivity is imperative, with the variance in lithium-ion concentration playing a determining role. Due to the permanent and temporary site-blocking effects, especially at non-dilute concentrations, not all Li-ions contribute to ionic conductivity. Here, we propose a strategy to directly calculate effective mobile ion concentration in which multiple-ion correlated migration is considered in the percolation analysis with the input of Li-ion distributions and hopping behavior based on kinetic Monte Carlo simulation, termed P-KMC. We provide examples of two representative lithium superionic conductors, cubic garnet-type Li x A 3 B 2 O 12 (0 ≤ x ≤ 9; A and B represent different cations) and perovskite-type Li x La 2/3− x /3 TiO 3 (0 ≤ x ≤ 0.5), to demonstrate the direct dependence of the ionic conductivity on the effective mobile ion concentration. This methodology provides a robust tool to identify the optimal compositions for the highest ionic conductivity in superionic conductors.