Issue 7, 2023

Substituting inert phosphate with redox-active silicate towards advanced polyanion-type cathode materials for sodium-ion batteries

Abstract

Polyanion-type phosphate materials with Na-super-ionic conductor structures are promising for next-generation sodium-ion battery cathodes, although the intrinsically low electroconductivity and limited energy density have restricted their practical applications. In this study, we put forward substituting an inert phosphate with a redox-active silicate to improve the energy density and intrinsic electroconductivity of polyanion-type phosphate materials, thus enabling an advance in sodium-ion battery cathodes. As a proof of concept, some of the phosphate of Na3V2(PO4)3 was replaced by silicate to fabricate Na3V2(PO4)2.9(SiO4)0.1, which exhibited a higher average discharge voltage of 3.36 V and a higher capacity of 115.8 mA h g−1 than pristine Na3V2(PO4)3 (3.31 V, 109.6 mA h g−1) at 0.5 C, therefore improving the energy density. Moreover, the introduced silicate enhanced the intrinsic electroconductivity of Na3V2(PO4)3 materials, as confirmed by both theoretical simulation and electrochemical measurements. After pairing with a commercial hard carbon anode, the optimized Na3V2(PO4)2.9(SiO4)0.1 cathode enabled a stable-cycling full cell with 90.1% capacity retention after 300 cycles at 5 C and a remarkable average coulombic efficiency of 99.88%.

Graphical abstract: Substituting inert phosphate with redox-active silicate towards advanced polyanion-type cathode materials for sodium-ion batteries

Supplementary files

Article information

Article type
Paper
Submitted
25 Nov 2022
Accepted
03 Jan 2023
First published
04 Jan 2023

Nanoscale, 2023,15, 3345-3350

Substituting inert phosphate with redox-active silicate towards advanced polyanion-type cathode materials for sodium-ion batteries

R. Sun, M. Dou, Y. Zhang, J. Chen, Y. Chen, B. Han, K. Xia, Q. Gao, X. Liu, Z. Cai and C. Zhou, Nanoscale, 2023, 15, 3345 DOI: 10.1039/D2NR06602E

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