Off-Stoichiometry of Sodium Iron Pyrophosphate as Cathode Materials for Sodium-Ion Batteries with Superior Cycling Stability

Yuhang Xin, Yingshuai Wang, Baorui Chen, Xiangyu Ding, Chunyu Jiang, Qingbo Zhou, Feng Wu, Hongcai Gao*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

As one of the important devices for large-scale electrochemical energy storage, sodium-ion batteries have received much attention due to the abundant resources of raw materials. However, whether it is a base station power source, an energy storage power station, or a start-stop power supply, long energy cycle life (more than 5000 cycles), high stability, and safety performance are application prerequisites. Regrettably, currently, few sodium-ion batteries can meet this requirement, mainly due to shortcomings in positive electrode performance. We report a sufficiently stable sodium-ion battery cathode material, Na2Fe0.95P2O7, that retains 97.5% capacity after 5000 charge/discharge cycles. The use of nonstoichiometry in the lattice enables simultaneous modification of the crystal and electronic structure, promoting Na2Fe0.95P2O7 to be extremely stable while still being able to achieve a capacity of 92 mAh g-1 and stable cycling at high temperatures up to 60 °C. Our results confirm the positive effect of nonstoichiometric ratios on the performance of Na2Fe0.95P2O7 and provide a reliable idea to promote the practical application of sodium-ion batteries.

Original languageEnglish
Pages (from-to)36509-36518
Number of pages10
JournalACS Applied Materials and Interfaces
Volume16
Issue number28
DOIs
Publication statusPublished - 17 Jul 2024

Keywords

  • cathode material
  • electrochemical energy storage
  • large-scale energy storage
  • sodium-ion batteries
  • the pyrophosphate structure

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