Relationship between network topology and negative electrode properties in Wadsley–Roth phase TiNb2O7

Abstract

Abstract Wadsley–Roth phase TiNb2O7, with an octahedral network consisting of TiO6 and NbO6, has attracted significant attention as a negative electrode material for lithium-ion batteries in recent years owing to its excellent safety and high discharge capacity. In this work, we investigated the effect of the network structure (intermediate-range structure), which is considered to form Li+ conduction pathways, on the electrode properties of TiNb2O7. To this end, we prepared TiNb2O7 samples with different charge/discharge properties and generated atomic configurations that simultaneously reproduce both total scattering and Bragg profile data. Topological analyses based on persistent homology demonstrated that the network disorder hidden in the average structure (crystal structure) significantly degrades the negative electrode properties. In conclusion, controlling the network topology is considered the key to improving the negative electrode properties of TiNb2O7.