Mirrored Stability and Reversibility in the Local Structure of Hydrated ZnxV2O5 for Aqueous Zinc Ion Shuttling

Abstract

Abstract. The hydrated vanadium oxide intercalated with various ions continues to spark interest as a possible candidate for multivalent ion cathode hosts. The zinc vanadium bronze (ZnxV2O5-yH2Oy∼0.25) as a Zn-ion intercalation cathode shows excellent cycling and competitive energy density. This operando and ex situ study, using synchrotron-based X-ray absorption near-edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), and near-edge X-ray absorption fine structure (NEXAFS), investigates the local electronic and geometric structure of this candidate material during electrochemical cycling in an aqueous electrochemical in-situ cell. The study reveals a clear charge compensation process upon ion intercalation by tracking the V-K absorption edge. The cycling stability and high-rate recovery are also assessed by comparing early cycle X-ray absorption (XAS) data and post-rapid-cycling XAS data. These experiments evince significant, yet highly reversible, local chemical and structural changes in this hydrated zinc vanadium oxide for multivalent ion (de)intercalation.