Oxygen vacancies enhance the lithium ion intercalation pseudocapacitive properties of orthorhombic niobium pentoxide.,Journal of Colloid and Interface Science

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Oxygen vacancies enhance the lithium ion intercalation pseudocapacitive properties of orthorhombic niobium pentoxide.
Journal of Colloid and Interface Science ( IF 9.4 ) Pub Date : 2019-12-06 , DOI: 10.1016/j.jcis.2019.12.015
Songmin Zhang ₁ , Guanglan Liu ₁ , Wenming Qiao ₁ , Jitong Wang ₁ , Licheng Ling ₁

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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 (H2) 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, theformation 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 (DLi) further explains the high rate-performance of H-Nb2O5. When the electrode thickness increased to 150 μm, 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.

中文翻译：

氧空位增强了正交晶态五氧化二铌的锂离子嵌入假电容特性。

正交晶态五氧化二铌（T-Nb2O5）是最有希望的具有快速锂离子（Li +）插层拟电容响应的储能材料之一，但在制成厚电极时要实现高速率的电荷转移反应仍然是一个关键的挑战。在本文中，我们报道了一种通过氢（H2）还原在T-Nb2O5中产生固有缺陷的简便方法，该方法有效克服了电化学利用率和速率能力的局限性。由于引入了大量的活性位，具有氧空位的氢化（H-）Nb2O5的比容量在0.5 A g-1时达到649 C g-1，大大超过了T-Nb2O5的580 C g-1的比容量。。此外，氧空位的形成导致供体密度增加和电导率提高，加快电荷存储动力学并实现出色的长期循环稳定性（2000次循环后保留86％）。电化学阻抗谱（EIS）图的分析和Li +扩散系数（DLi）的计算进一步说明了H-Nb2O5的高倍率性能。当电极厚度增加到150μm时，H-Nb2O5仍具有出色的电化学性能。因此，氧空位的引入为改善各种过渡金属氧化物的电化学性能提供了一种新的方法。当电极厚度增加到150μm时，H-Nb2O5仍具有出色的电化学性能。因此，氧空位的引入为改善各种过渡金属氧化物的电化学性能提供了一种新的方法。当电极厚度增加到150μm时，H-Nb2O5仍具有出色的电化学性能。因此，氧空位的引入为改善各种过渡金属氧化物的电化学性能提供了一种新的方法。

更新日期：2019-12-06

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