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

Li 4 Ti 5 O 12 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 Nb 2 O 5 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 Nb 2 O 5-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 Nb 2 O 5-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 Nb 2 O 5 and Li 4 Ti 5 O 12 , thanks to more available surface/sub-surface reaction sites and significantly improved fast ion and electron conductivity.