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Isostructural and Multivalent Anion Substitution toward Improved Phosphate Cathode Materials for Sodium‐Ion Batteries
Author(s) -
Wang MeiYi,
Guo JinZhi,
Wang ZhiWei,
Gu ZhenYi,
Nie XueJiao,
Yang Xu,
Wu XingLong
Publication year - 2020
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201907645
Subject(s) - isostructural , cathode , electrochemistry , ion , materials science , chemical engineering , conductivity , inorganic chemistry , phosphate , sodium , chemistry , crystal structure , crystallography , electrode , organic chemistry , metallurgy , engineering
Abstract Polyanion‐type phosphate materials are highly promising cathode candidates for next‐generation batteries due to their excellent structural stability during cycling; however, their poor conductivity has impeded their development. Isostructural and multivalent anion substitution combined with carbon coating is proposed to greatly improve the electrochemical properties of phosphate cathode in sodium‐ion batteries (SIBs). Specifically, multivalent tetrahedral SiO 4 4− substitute for PO 4 3− in Na 3 V 2 (PO 4 ) 3 (NVP) lattice, preparing the optimal Na 3.1 V 2 (PO 4 ) 2.9 (SiO 4 ) 0.1 with high‐rate capability (delivering a high capacity of 82.5 mAh g −1 even at 20 C) and outstanding cyclic stability ( ≈ 98% capacity retention after 500 cycles at 1 C). Theoretical calculation and experimental analyses reveal that the anion‐substituted Na 3.1 V 2 (PO 4 ) 2.9 (SiO 4 ) 0.1 reduces the bandgap of NVP lattice and enhanced its structural stability, Na + ‐diffusion kinetics and electronic conductivity. This strategy of multivalent and isostructural anion substitution chemistry provides a new insight to develop advanced phosphate cathodes.