Recognition of V3+/V4+/V5+ Multielectron Reactions in Na3V(PO4)2: A Potential High Energy Density Cathode for Sodium-Ion Batteries

Molecules. 2020 Feb 24;25(4):1000. doi: 10.3390/molecules25041000.

Abstract

Na3V(PO4)2 was reported recently as a novel cathode material with high theoretical energy density for Sodium-ion batteries (SIBs). However, whether V3+/V4+/V5+ multielectron reactions can be realized during the charging process is still an open question. In this work, Na3V(PO4)2 is synthesized by using a solid-state method. Its atomic composition and crystal structure are verified by X-ray diffraction (XRD) and neutron diffraction (ND) joint refinement. The electrochemical performance of Na3V(PO4)2 is evaluated in two different voltage windows, namely 2.5-3.8 and 2.5-4.3 V. 51V solid-state NMR (ssNMR) results disclose the presence of V5+ in Na2-xV(PO4)2 when charging Na3V(PO4)2 to 4.3 V, confirming Na3V(PO4)2 is a potential high energy density cathode through realization of V3+/V4+/V5+ multielectron reactions.

Keywords: energy density; multielectron reaction; polyanion; solid-state NMR.

MeSH terms

  • Cations, Monovalent
  • Electric Power Supplies*
  • Electricity
  • Electrochemical Techniques
  • Electrodes
  • Electrons*
  • Humans
  • Sodium / chemistry*
  • Solar Energy
  • Vanadium Compounds / chemical synthesis
  • Vanadium Compounds / chemistry*

Substances

  • Cations, Monovalent
  • Vanadium Compounds
  • Sodium