期刊
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
卷 24, 期 1, 页码 17-24出版社
SPRINGER
DOI: 10.1007/s10008-019-04448-6
关键词
Sodium-ion batteries; High-voltage cathode; Phosphates; Electrolytes; In situ PXRD
The electrochemical properties of carbon and reduced graphene-coated Na4Ni3(PO4)(2)P2O7 materials have been evaluated as high-voltage positive electrodes for sodium-ion batteries. Na4Ni3(PO4)(2)P2O7 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)(2)P2O7-reduced graphene oxide and Na4Ni3(PO4)(2)P2O7-carbon composites. The high-voltage dimethyl carbonate-based electrolyte has been chosen to explore the electrochemical properties of Na4Ni3(PO4)(2)P2O7 as a cathode. Carbon-coated Na4Ni3(PO4)(2)P2O7 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)(2)P2O7 material for the next generation sodium-ion batteries.
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