Na 3 MnZr(PO 4 ) 3: A High-Voltage Cathode for Sodium Batteries

Hongcai Gao, Ieuan D. Seymour, Sen Xin, Leigang Xue, Graeme Henkelman, John B. Goodenough* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

201 Citations (Scopus)

Abstract

Sodium batteries have been regarded as promising candidates for large-scale energy storage application, provided cathode hosts with high energy density and long cycle life can be found. Herein, we report NASICON-structured Na 3 MnZr(PO 4 ) 3 as a cathode for sodium batteries that exhibits an electrochemical performance superior to those of other manganese phosphate cathodes reported in the literature. Both the Mn 4+ /Mn 3+ and Mn 3+ /Mn 2+ redox couples are reversibly accessed in Na 3 MnZr(PO 4 ) 3 , providing high discharge voltage plateaus at 4.0 and 3.5 V, respectively. A high discharge capacity of 105 mAh g -1 was obtained from Na 3 MnZr(PO 4 ) 3 with a small variation of lattice parameters and a small volume change on extraction of two Na + ions per formula unit. Moreover, Na 3 MnZr(PO 4 ) 3 exhibits an excellent cycling stability, retaining 91% of the initial capacity after 500 charge/discharge cycles at 0.5 C rate. On the basis of structural analysis and density functional theory calculations, we have proposed a detailed desodiation pathway from Na 3 MnZr(PO 4 ) 3 where Mn and Zr are disordered within the structure. We further show that the cooperative Jahn-Teller distortion of Mn 3+ is suppressed in the cathode and that Na 2 MnZr(PO 4 ) 3 is a stable phase.

Original languageEnglish
Pages (from-to)18192-18199
Number of pages8
JournalJournal of the American Chemical Society
Volume140
Issue number51
Early online date2 Dec 2018
DOIs
Publication statusPublished - Dec 2018

Bibliographical note

Acknowledgements:
The synthesis, analysis, and electrochemical characterization of the electrode material were supported by the U.S. Department of Energy, Office of Basic Energy Sciences (Grant number DE-SC0005397). J.B.G and G.H also acknowledge support from the Robert A. Welch Foundation (Grants F-1066 and F-1841). The calculations were done at the National Energy Research Scientific Computing Center and the Texas Advanced Computing Center.

Data Availability Statement

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/jacs.8b11388.
Experimental details; computational methodology; TGA of the cathode material; XRD pattern and TEM image of the cycled cathode; structure of supercells for DFT calculations; XPS spectra of the cathode at different charging state; crystallographic data of the cathode material; comparison with other cathode materials; magnetic moment and Bader charge calculations (PDF).

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