Structural Influences on Lithium-Ion Transport in Bismuth Oxides: A Molecular Dynamics Approach

TL;DR

This study uses simulations to explore how the structure of bismuth oxide affects lithium-ion movement, aiming to improve solid electrolytes for batteries.

Contribution

The study reveals how structural features like layering and void fraction influence Li-ion transport in bismuth oxides.

Findings

Layered bismuth oxide structures show simpler and more efficient Li-ion diffusion pathways.

Li-free bismuth oxide phases with minimal void fraction exhibit the highest Li-ion diffusivity.

A strong inverse relationship exists between void fraction and Li-ion transport efficiency.

Abstract

This study investigates Li-ion diffusion characteristics in Li-contained and Li-free bismuth oxide crystals, aiming to explore their potential as solid electrolytes for next-generation lithium-ion batteries. Although bismuth oxide has been widely applied as a solid electrolyte in fuel cells, its suitability for Li-ion battery applications remains unexplored. Using molecular dynamics simulations, we analyzed the Li-ion diffusion behavior in two distinct Li-contained bismuth oxide crystals with layered and non-layered structures, as well as four Li-free bismuth oxide phases. It is demonstrated that the layered structure exhibits a simpler and more organized diffusion pathway compared to the complex and bottlenecked pathways in the non-layered structure, resulting in superior Li-ion diffusivity. For Li-free bismuth oxide phases, diffusion coefficients vary significantly depending on structural characteristics, with the highest diffusion coefficient observed in the phase with minimal void fraction. A notable inverse relationship between void fraction and Li-ion diffusivity efficiency highlights the importance of structural design in enhancing ionic transport. This study provides valuable insights into the diffusion mechanisms of Li ions in bismuth oxide systems and offers strategic guidance for designing high-performance solid electrolytes, contributing to the advancement of all-solid-state battery technologies.

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