High-power lithium-ion capacitor using orthorhombic Nb 2 O 5 nanotubes enabled by cellulose-based electrospun scaffolds
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ORIGINAL RESEARCH
High-power lithium-ion capacitor using orthorhombic Nb2O5 nanotubes enabled by cellulose-based electrospun scaffolds Jong Chel Park . Sangbaek Park . Dong-Wan Kim
Received: 4 July 2020 / Accepted: 15 September 2020 Ó Springer Nature B.V. 2020
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 electronconducting 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 onedimensional 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.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10570-020-03468-0) contains supplementary material, which is available to authorized users. J. C. Park D.-W. Kim (&) School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea e-mail: [email protected] S. Park (&) Center for Energy Materials Research, Korea Institute of Science and Technology (KIST), Seoul 02792, South Korea e-mail: [email protected]
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Cellulose
Graphic abstract
Keywords Electrospinning Cellulose T-Nb2O5 nanotubes Lithium-ion capacitor Supercapacitor
Introduction Supercapacitors are considered a next-generation energy storage device capable of fast charging within a few seconds, long-term cycling stability, and high power density (Brezesinski et al. 2010a, b; Kim et al. 2012; Augustyn et al. 2013; Come et al. 2014; Wang et al. 2016; Xiong et al. 2018; Li et al. 2019a, b). Their energy storage mechanisms are basically different from those of conventional Li-ion batteries, wherein the capacitance usually emerges from surface reactions such as those that are characteristic of capacitive behaviors (Conway 1991, 2013; Ko¨tz and Carlen 2000). Particularly, transition metal oxides with pseudocapacitive behaviors indicate much higher specific capacitance compared than
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