期刊
ADVANCED FUNCTIONAL MATERIALS
卷 32, 期 12, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.202107060
关键词
fast charging; intercalation pseudocapacitance; lithium-ion batteries; oxygen vacancies; T-Nb; O-2; (5)
类别
资金
- National Key R&D Program of China [2016YFB0901600]
- NSAF [U1830113]
- National Natural Science Foundation of China [51772313, 21975276]
- Shanghai Science and Technology Committee [20520710800]
- DOE Office of Science [DE-SC0012704]
This study investigated a method to improve the low electric conductivity and particle pulverization issues of T-Nb2O5 by enriching oxygen vacancies, thereby enhancing its electric conductivity and electrochemical kinetics, and constructing a Nb2O5-x electrode with excellent cycling stability and high-rate performance under the control of oxygen defects.
Metastable orthorhombic niobium pentoxide (T-Nb2O5) is a promising anode to fulfill the requirements for high-rate Li-ion batteries (LIBs). Stoichiometric T-Nb2O5 is plagued by low electric conductivity and particle pulverization after repeated charge/discharge processes. In this work, oxygen vacancies are implanted into T-Nb2O5 particles via acid immersion of Nb2O5 center dot nH(2)O with the formation of Lewis acid sites. The multiple characterizations and simulations reveal the lengthening of Nb-O bonds, and the transformation from NbO7 pentagonal bipyramids and NbO6 tetragonal bipyramids in T-Nb2O5-x. The enrichment of oxygen vacancies endows T-Nb2O5-x with higher electric conductivity, better electrochemical kinetics, larger pseudocapacitive contribution. O-doped graphitic C3N4 is creatively proposed as a trace oxygen pump to repair excessive oxygen vacancies, and it also serves as a sacrifice template for Nb2O5-x growth to construct a porous and monolithic electrode network. Defect-modulated Nb2O5-x displays extraordinary cycling stability (164 mAh g(-1) at 5 C after 1100 cycles), high capacity retention (104 mAh g(-1)) at an ultrahigh rate (25 C), and large areal capacity (0.74 mAh cm(-2)) under high mass loading (4 mg cm(-2)). The practical prospect is proved by Nb2O5-x/LiNi0.8Co0.1Mn0.1O2 full cells with high average platform (2.12 V) and high specific capacity (229 mAh g(-1)). The oxygen-defect modulation strategy on oxide anodes provides an alternative solution to fast-charging and durable LIBs.
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