Free-standing Sandwich Structure MoO 3 -rGO Composite Film Electrode for Flexible Supercapacitors
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.266
Free-standing Sandwich Structure MoO3-rGO Composite Film Electrode for Flexible Supercapacitors Le Yu1,2, Shixi Zhao1, Qilong Wu1,2, Xiaoxiao Zheng1,2, Yifeng Wang1,2, Guodan Wei*,3 1
Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, P. R. China
2
School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China
3
Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518057, P. R. China
ABSTRACT: The research of high-performance flexible supercapacitors is urgent due to the rapid development of wearable and portable electronics. The key challenge is the preparation of flexible electrodes with high areal capacitance since electrodes are the most important part of supercapacitors. Compared to those conventional electrodes loading with typical flexible substrates such as textile, PET, paper et al, free-standing electrodes have many advantages such as more efficient capacity contribution, solidly embedded active materials and thinner thickness. Herein, we have successfully fabricated a novel sandwich-like structure freestanding MoO3-rGO (reduced graphene oxide) composite film electrode for flexible supercapacitors using simple vacuum filtration method followed by HI reduction process. The obtained MoO3-rGO composite film electrode shows excellent electrochemical performance, whose areal specific capacitance reaches 8972 mF·cm-2 (1.5 mA·cm-2). Here, MoO3 provides pseudocapacitance and rGO provides double-layer capacitance. After cycling for 2000 cycles, the capacity retention is 86.7%, showing good cycle stability. Besides, the as-prepared composite film has good flexibility and will not break easily during following bending, rolling, folding or twisting steps. This study has been approved to be an important step for the highperformance electrode design for free-standing flexible supercapacitors.
INTRODUCTION Intelligent electronics have developed towards folding, wearable, portable devices and so on, which puts forward higher requirements for flexible energy storage devices. Ideal flexible energy storage devices needs not only high energy and power density, but also good flexibility, high mechanical strength, thin thickness as well as light
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mass for portability [1-2]. Among all kinds of energy storage devices, supercapacitors are good candidates for flexible energy storage devices because their significant advantages of high power density, high safety and simple structure [3-4]. However, it still remains challenging to fabricate flexible and free-standing electrodes. One way to prepare a flexible electrode is loading active materials on flexible substrate, such as textile, PET, paper [5] and so on. Generally, these subs
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