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One pot preparation of CoMoO4 nanowires covered by CoMoO4 nanosheets for application in asymmetric supercapacitors Jing Wang1,* 1 2

, Shen Wang2, Jiang Chang1, and Xiangyang Jin1

School of Light Industry, Harbin University of Commerce, Harbin 150028, People’s Republic of China MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China

Received: 10 July 2020

ABSTRACT

Accepted: 3 October 2020

In this work, we report for the first time to prepare the CoMoO4 materials by a one-step simple water bath heating process. The morphology of the materials changes greatly when the temperature changes at a certain stage. The experimental results indicate the CoMoO4 is nanowire structure at 90 °C. When the temperature is 150 °C, the morphology of CoMoO4 is nanosheet structure. What is interesting in the experiment is that when we continuously adjust the temperature from 90 to 150 °C, we found that the CoMoO4 nanowires were covered by CoMoO4 nanosheets. The electrochemical performances of CoMoO4 nanowires, CoMoO4 nanosheets, and CoMoO4 nanowires covered by CoMoO4 nanosheets were researched. The electrochemical test results show that the CoMoO4 nanowires covered by CoMoO4 nanosheets demonstrate high specific capacitance 1960 F/g at a current density of 1 A/g, rate property 64.29%, and cycle performance with 98.79% capacitance retention after 10000 cycles. Furthermore, the CoMoO4 nanowires covered by CoMoO4 nanosheets were used as the positive material and active carbon as the negative material were assembled into the asymmetric supercapacitor device. This asymmetric supercapacitor device shows high energy density 55.47 Wh/kg and power density 12000 Wh/ kg, and cycle performance with the capacitance retention 92.86% after 10000 cycles. These excellent results indicate the CoMoO4 nanowires covered by CoMoO4 nanosheets have potential competition in energy storage.

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Springer Science+Business

Media, LLC, part of Springer Nature 2020

Address correspondence to E-mail: [email protected]

https://doi.org/10.1007/s10854-020-04604-z

J Mater Sci: Mater Electron

1 Introduction In recent years, serious environmental pollution and energy shortage have brought a lot of inconvenience to human life. Therefore, green and clean energy is increasingly important and needed. Among the numerous energy storage devices, supercapacitors are considered as one of the most satisfactory devices [1–3]. Because of their high power density, easy to maintain, fast charge and discharge, long cycle life and many other advantages, which are favored by researchers [4, 5]. However, the disadvantage is that the low energy density compared with Li batteries will limit its further used in practice. The energy density can be improved by the selection of materials and widening the voltage window according to the equation of energy density E ¼ 1=2CV2 [6, 7]. Usually, the electrode materials can be divided in