Surface nitrided and carbon coated TiNb2O7 anode material with excellent performance for lithium-ion batteries
Surface nitrided and carbon coated TiNb2O7 anode material with excellent performance for lithium-ion batteries
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DOI：
10.1016/j.jallcom.2020.155241
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发表时间：
2020-09-15
影响因子：
6.2
通讯作者：
Yin, Geping
中科院分区：
文献类型：
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作者：
Gao, Jinlong;Cheng, Xinqun;Yin, Geping
氧化钛（TiNb2O7）由于具有五电子传递机制，具有较高的能量密度，被认为是锂离子电池极具前景的负极材料。然而，由于电子导电性差和Li+扩散率低，其实际应用受到严重限制。在这里，我们报道了一种新的表面氮化和碳包覆的TiNb2O7 (N-TiNb2O7@C)，采用双氰胺（DCDA）作为碳源和氮源，通过简单的改性工艺。经过煅烧处理后，在TiNb2O7表面包裹了一层薄薄的碳层，同时颗粒表面的部分Nb5+也被还原成NbN。获得的N-TiNb2O7@C提供了165 mAh的可逆容量。g（-1）和135 mAh。g（-1）分别在20℃和50℃的速率下。在10℃下还测量了良好的可循环性，其中容量保持在109.6 mAh。G(-1)，容量保持率为82.7%。N-TiNb2O7@C的优异性能可归因于煅烧过程中的碳涂层、表面氮化和Nb5+还原，共同提高了电子导电性和Li+扩散率。本研究展示了一种简便的改性工艺，可以有效地提高锂离子电池用TiNb2O7的电化学性能。(C) 2020 Elsevier B.V.版权所有
Owing to the five-electron transfer mechanism, titanium niobium oxide (TiNb2O7) possesses high energy density and is considered to be a promising anode candidate for Li-ion batteries. However, its practical application is severely limited due to the poor electronic conductivity and the low Li+ diffusivity. Here, we report a novel surface nitrided and carbon coated TiNb2O7 (N-TiNb2O7@C) via a facile modification process using dicyandiamide (DCDA) as both carbon and nitrogen sources. After a calcination process, TiNb2O7 was coated by a thin carbon layer, while part of the Nb5+ on the particle surface was reduced to form NbN simultaneously. The obtained N-TiNb2O7@C delivered the reversible capacities of 165 mAh.g(-1) and 135 mAh.g(-1) at the rates of 20 C and 50 C, respectively. Good cyclability at 10 C was also measured where the capacity remained at 109.6 mAh.g(-1) after 1000 cycles, featuring a capacity retention of 82.7%. The excellent performance of N-TiNb2O7@C can be attributed to the carbon coating, surface nitridation and Nb5+ reduction during the calcining process, which together improve the electronic conductivity and Li+ diffusivity. This study demonstrates a facile modification process to effectively improve the electrochemical performance of TiNb2O7 for Li-ion batteries. (C) 2020 Elsevier B.V. All rights reserved.