R-Nb2O5 has an ‘idealized’ V2O5 structure and Wadsley–Roth-like structural stability during Li-ion battery cycling

Abstract

The adoption of batteries across diverse applications requires electrode materials with a wider range of performance metrics, such as cost, safety, and material availability. Along the path to discovering new commercially viable materials, a fundamental understanding of chemical and atomic structure features that provide structural stability and effective ion transport is essential. In support of new understanding, we report the cycling behavior of metastable R-Nb₂O₅. R-Nb₂O₅ adopts an ‘idealized’ V₂O₅ structure, in which [NbO₆] octahedra alternate in edge- and corner-sharing resulting in ReO₃-like slabs, whereas Wadsley–Roth materials have ReO₃-like blocks, linked through edge-sharing octahedra at intersecting crystallographic shear planes. We find that this slab structure is stable during cycling, with minor atomic structure changes and cycling curves that are symmetric on discharge and charge, resembling the behavior of Wadsley–Roth materials more than other related materials, such as ReO₃, V₂O₅, or Nb₃O₇F. Based on our findings, R-Nb₂O₅ can serve as a ‘structural bridge’ between Wadsley–Roth block structures and V₂O₅, through which we can relate inter- and intra-polyhedral structures to cycling behavior and structural stability during cycling.