Journal
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Volume 562, Issue -, Pages 193-203Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2019.12.015
Keywords
Orthorhombic Nb2O5; Oxygen vacancies; Li+ intercalation pseudocapacitance
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Funding
- National Natural Science Foundation of China [U1710252]
- Young Elite Scientists Sponsorship Program by CAST [2017QNRC001]
- Fundamental Research Funds for the Central Universities [222201817001, 50321041918013]
- Shanghai Rising Star Program [17QB1401700]
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While orthorhombic niobium pentoxide (T-Nb2O5) is one of the most promising energy storage material with rapid lithium ion (Li+) intercalation pseudocapacitive response, a key challenge remains the achievement of high-rate charge-transfer reaction when fabricated into thick electrodes. Herein, we report a facile method to create intrinsic defects in T-Nb2O5 through a hydrogen (H-2) reduction, which is effective to overcome the limitations of electrochemical utilization and rate capability. Due to the high number of active sites introduced, the specific capacity of hydrogenated (H-) Nb2O5 with oxygen vacancies reaches 649 C g(-1) at 0.5 A g(-1), greatly exceeding that of T-Nb2O5 which is 580 C g(-1). In addition, the formation of oxygen vacancies leads to increased donor density and enhanced electrical conductivity, which accelerates charge storage kinetics and enables excellent long-term cycling stability (86% retention after 2000 cycles). The analysis of electrochemical impedance spectroscopy (EIS) plots and the calculation of Li+ diffusion coefficients (D-Li) further explains the high rate-performance of H-Nb2O5. When the electrode thickness increased to 150 mu m, the H-Nb2O5 still delivers excellent electrochemical properties. Therefore, the introduction of oxygen vacancies provides a new method towards the improvement of the electrochemical properties of various transition metal oxides. (C) 2019 Elsevier Inc. All rights reserved.
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