Eliminating crystal water enables enhanced sodium storage performance in an oxalate-phosphate cathode material

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Article number107898
Journal / PublicationChinese Chemical Letters
Volume34
Issue number8
Online published14 Oct 2022
Publication statusPublished - Aug 2023

Abstract

The oxalate-phosphate polyanion-mixed cathode materials are promising for sodium-ion batteries (SIBs) due to their unique open-framework structures and high voltage property. However, materials of this type generally contain crystal water molecules in the lattice frameworks, which may affect their energy storage properties. This work aims to disclose the impacts of crystal water on physiochemical and electrochemical properties of Na2(VO)2(HPO4)2(C2O4)·2H2O (NVPC-W). It shows that the water molecules can be eliminated by vacuum drying at 150 °C. The elimination of water molecules does not change the crystal phase of the material, while the obtained Na2(VO)2(HPO4)2(C2O4) (NVPC) exhibits significant improvements in cycling stability, Coulombic efficiency, as well as rate performances. Kinetics analysis indicates that the existence of lattice water molecules hinders sodium-ion diffusion and promotes the degradation of electrodes. We believe the findings can help to develop high-performance cathode materials. © 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Research Area(s)

  • Battery, Cathode, Crystal water, Energy storage, V-based materials