Topochemical stabilization and single-crystal transformations of a metastable 2D γʹ-V2O5 intercalation cathode

Abstract

The atomistic design of positive electrode materials requires understanding of (1) how guest cations diffuse through an intercalation host to fill empty interstices and (2) the distortions of the host lattice induced as a result of ion intercalation. Here, we report the use of topochemistry to access single-crystals of a metastable 2D van der Waals solid, γʹ-V2O5, and examine its single-crystal-to-single-crystal transformations upon lithiation up to γ-LiV2O5. High-resolution single-crystal diffraction provides an atomistic view of preferred interstitial sites occupied by Li ions and distortions of the 2D lattice in an extended solid-solution lithiation regime, which stands in stark contrast to the thermodynamic α-V2O5 phase. These results illustrate the potential of metastable compounds with reconfigured atomic connectivity to unlock lithiation pathways and mechanisms that are profoundly different from their thermodynamic counterparts. The study furthermore demonstrates the viability of combining topochemical modification with single-crystal diffraction to image intercalation phenomena with atomic resolution.