Orthorhombic Nb2O5-x for Durable High-Rate Anode of Li-Ion Batteries

• Published in: iScience Vol. 23; no. 1; p. 100767
• Main Authors: Liu, Zichao, Dong, Wujie, Wang, Jianbo, Dong, Chenlong, Lin, Yue, Chen, I-Wei, Huang, Fuqiang
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 24.01.2020; Elsevier
• Subjects: Chemical Synthesis; Energy Materials; Energy Storage; Energy Materials; Energy Storage; Chemical Synthesis
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2019.100767

Li4Ti5O12 anode can operate at extraordinarily high rates and for a very long time, but it suffers from a relatively low capacity. This has motivated much research on Nb2O5 as an alternative. In this work, we present a scalable chemical processing strategy that maintains the size and morphology of nano-crystal precursor but systematically reconstitutes the unit cell composition, to build defect-rich porous orthorhombic Nb2O5-x with a high-rate capacity many times those of commercial anodes. The procedure includes etching, proton ion exchange, calcination, and reduction, and the resulting Nb2O5-x has a capacity of 253 mA h g−1 at 0.5C, 187 mA h g−1 at 25C, and 130 mA h g−1 at 100C, with 93.3% of the 25C capacity remaining after cycling for 4,000 times. These values are much higher than those reported for Nb2O5 and Li4Ti5O12, thanks to more available surface/sub-surface reaction sites and significantly improved fast ion and electron conductivity. [Display omitted] •A novel micro-etching strategy is developed to prepare porous nano-crystal Nb2O5•The obtained Nb2O5 remains the morphology of the precursor but reconstructs unit cell•Oxygen vacancies and Nb4+/Nb5+ are introduced to porous Nb2O5-x by anoxic annealing•Defect-rich and porous Nb2O5-x works as durable, high-rate, and safe anode of LIBs Energy Storage; Chemical Synthesis; Energy Materials