Molten Na reduced T-Nb2O5 nanorods enable enhanced Na-storage performance

Abstract

Abundant oxygen vacancies are generated on the surface of the T-Nb2O5 nanorods by a molten Na reduction method, which is accomplished by immersing the pristine T-Nb2O5 nanorods into a melting Na liquid for a short period (30 min) at low temperature (200 °C). The incorporation of such oxygen vacancies gives black T-Nb2O5 nanorods and brings the advantages of enhanced sodium storage capacity, rate performance, and cycle stability, which originate from the expanded interplanar space, increased electronic conductivity, and boosted ion diffusion kinetics. The optimized T-Nb2O5 nanorods electrode delivers a capacity of 100.7 mAh/g at 1C and maintains 44.1 mAh/g at 5C after 1000 cycles, which is superior to those of the pristine sample and conventional H2 reduced samples. This work proposes a new and effective method for modulating oxygen vacancies and emphasizes the importance of modulating oxygen vacancies in metal oxide electrode materials toward high-performance sodium-ion batteries.