Unlocking the chemical space in anti-perovskite conductors by incorporating anion rotation dynamics

CH Guan and Y Yang and RX Ouyang and HR Jing and JQ Yan and GY Li and HA Duan and H Zhu, ENERGY STORAGE MATERIALS, 62, 102936 (2023).

DOI: 10.1016/j.ensm.2023.102936

Anti-perovskite compounds have drawn significant research interest as promising next-generation electrolytes for solid-state batteries, due to the high chemical stability against Li-metal, the negligible electronic conductivity and low cost. However, the low ionic conductivity, and the deficient fundamental understandings of ion transports impede the further optimization of the lithium anti-perovskite electrolytes. Herein, we reveal that exchanging anion lattice sites in the anti- perovskite could promote the structure stabilities and ionic conduc- tivities simultaneously, by incorporating the rotational dynamics of anion clusters and strengthening the coupling between Li migrations and cluster rotations. Based on high-throughput calculations by density func-tional theory (DFT), twelve new anti-perovskite materials are predicted to exhibit superionic conductivity, among which the highest ionic conductivity of 10.9 mS/cm in Li3BrSO4 can be achieved (hundreds of times higher than the ionic conductivity of typical Li3OCl antiperovskite, 0.021 mS/cm). Furthermore, the local dif-ference frequency center is proposed to quantitatively characterize the coupled degree of Li migration and cluster rotation, revealing the contribution of paddlewheel effect to the ionic conductivity. Our proposed cation- anion dynamics coupling in site-exchanged and cluster-based antiperovskites not only open a new avenue for under-standing the key role played by rotational dynamics on fast lithium mobility, but also can be generally applied to develop other fast ionic conductors with cluster dynamics.

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