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Electrochemical investigations of high-voltage Na4Ni3(PO4)2P2O7 cathode for sodium-ion batteries...

by P. Ramesh Kumar, Hamdi Ben Yahia, Ilias Belharouak, Md Ruhul Amin, Rachid Essehli
Publication Type
Journal
Journal Name
Journal of Solid State Electrochemistry
Publication Date
Page Numbers
17 to 24
Volume
24
Issue
1

The electrochemical properties of carbon and reduced graphene-coated Na4Ni3(PO4)2P2O7 materials have been evaluated as high-voltage positive electrodes for sodium-ion batteries. Na4Ni3(PO4)2P2O7 exhibits the highest Ni3+/Ni2+ redox potential of 4.8 V vs. Na+/Na with a theoretical capacity of 127 mAh g−1. Here, we report on the synthesis and characterizations of Na4Ni3(PO4)2P2O7-reduced graphene oxide and Na4Ni3(PO4)2P2O7-carbon composites. The high-voltage dimethyl carbonate–based electrolyte has been chosen to explore the electrochemical properties of Na4Ni3(PO4)2P2O7 as a cathode. Carbon-coated Na4Ni3(PO4)2P2O7 composite electrode delivers a stable discharge capacity of 51 mAh g−1 at 0.1 C rate for 40 cycles which corresponds to a reversible intercalation/de-intercalation of 1.3 sodium ions. The structural deformation has been observed during the charge–discharge process beyond the removal of 1.3 Na+ ions and has been confirmed by in situ PXRD measurements. The present results provide a guideline to improve the performances of the high-voltage Na4Ni3(PO4)2P2O7 material for the next generation sodium-ion batteries.