Operando  XAFS on a Hydrated Calcium Vanadium Bronze Cathode for Aqueous Zn-ion Storage

Chemphyschem. 2021 Nov 19. doi: 10.1002/cphc.202100674. Online ahead of print.ABSTRACTMultivalent ion storage and aqueous electrochemical systems continue to build interest for energy application. The Zn-ion system with 2 electron transfer and an ideal metal anode is a strong candidate but is still at the early stage of development. Using both in-situ near-edge (XANES) and X-ray absorption fine structure spectroscopy, EXAFS, a nanostructured cathode material, Ca x V 2 O 5 -H 2 O (CVO), was probed at the V- K absorption edge. This operando study determined the local electronic and geometric structure changes for CVO during galvanostatic cycling as the active material in an aqueous Zn-ion cell. The XANES data provides a fine resolution to track the evolution of the vanadium oxidative state and near-neighbor coordination sphere showing subtle shifts and delocalized charge. The Zn-ion influence on the V- K absorption edge are visualized using a difference technique called Δμ. Coupled with theoretical calculations and modeling, the extended region further confirms excellent electronic and structural reversibility of this vanadium oxide bronze in an aqueous Zn-ion electrochemical cell.PMID:34799966 | DOI:10.1002/cphc.202100674
Source: Chemphyschem - Category: Chemistry Authors: Source Type: research