Abstract

Orthorhombic Nb₂O₅-based nanoarchitectures have shown promise as electrode materials for Li-ion capacitors because they improve lithium ion transport and conductivity of Nb₂O₅ with high theoretical capacity. However, despite the several advantages of nanotubes, the facile synthesis of Nb₂O₅ nanotubes remains challenging. Herein, we present Nb₂O₅ nanotubes as an efficient ion- and electron-conducting electrode using environmentally friendly cellulose as sacrificial templates. The rational synthetic design based on sol–gel interactions with hydroxyl groups on the cellulosic surface enables uniformly covering the electrospun-cellulose one-dimensional templates with Nb₂O₅, resulting in unusual nanotubular Nb₂O₅ crystals featuring crystallographic iso-orientation owing to a controlled two-step calcination. Such crystallographically oriented nanotubes are favorable to fast Li⁺ intercalation kinetics for pseudocapacitive behavior with efficient lithium ion channels. The orthorhombic Nb₂O₅ nanotubes provide electrodes with a high initial capacity (163 mAh g⁻¹), excellent rate capability (95 mAh g⁻¹ at 5 A g⁻¹), and stable cycle performance (81.8% retention after 1000 cycles at 5 A g⁻¹) without any carbon composite and are thus superior to previously reported Nb₂O₅ electrodes. This simple strategy can open a new avenue for fabricating nanotubes of various transition metal oxides.

Graphic abstract

中文翻译：

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基于纤维素静电纺丝支架的正交晶体Nb 2 O 5纳米管的大功率锂离子电容器

摘要

正交晶的Nb ₂ O ₅基纳米体系结构有望成为锂离子电容器的电极材料，因为它们以较高的理论容量提高了锂离子的传输和Nb ₂ O _5的电导率。然而，尽管纳米管具有若干优点，但要容易地合成Nb ₂ O ₅纳米管仍然具有挑战性。在这里，我们介绍Nb ₂ O ₅纳米管作为高效的离子和电子导电电极，使用环保的纤维素作为牺牲模板。基于溶胶-凝胶与纤维素表面羟基的相互作用的合理合成设计可以使Nb ₂ O ₅均匀覆盖电纺纤维素一维模板，从而导致不寻常的纳米管Nb ₂ O ₅晶体由于受控的两步煅烧。这种晶体学取向的纳米管有利于具有有效锂离子通道的假电容行为的快速Li ⁺嵌入动力学。斜方Nb ₂ O ₅纳米管提供具有高的初始容量（163毫安克电极^-1），优良的速率能力（95毫安克^-1在5 A G ^-1），和稳定的循环性能（1000次循环后81.8％保留在5A克^-1）不含任何碳复合物，因此优于先前报道的Nb ₂ O ₅电极。这种简单的策略可以为制造各种过渡金属氧化物的纳米管开辟新途径。

图形摘要