Asymmetric Flexible MXene-Reduced Graphene Oxide Micro-Supercapacitor

Abstract
Current microfabrication of micro-supercapacitors often involves multistep processing and delicate lithography protocols. In this study, simple fabrication of an asymmetric MXene-based micro-supercapacitor that is flexible, binder-free, and current-collector-free is reported. The interdigitated device architecture is fabricated using a custom-made mask and a scalable spray coating technique onto a flexible, transparent substrate. The electrode materials are comprised of titanium carbide MXene (Ti3C2Tx) and reduced graphene oxide (rGO), which are both 2D layered materials that contribute to the fast ion diffusion in the interdigitated electrode architecture. This MXene-based asymmetric micro-supercapacitor operates at a 1 V voltage window, while retaining 97% of the initial capacitance after ten thousand cycles, and exhibits an energy density of 8.6 mW h cm−3 at a power density of 0.2 W cm−3. Further, these micro-supercapacitors show a high level of flexibility during mechanical bending. Utilizing the ability of Ti3C2Tx-MXene electrodes to operate at negative potentials in aqueous electrolytes, it is shown that using Ti3C2Tx as a negative electrode and rGO as a positive one in asymmetric architectures is a promising strategy for increasing both energy and power densities of micro-supercapacitors.

Citation
Couly C, Alhabeb M, Van Aken KL, Kurra N, Gomes L, et al. (2017) Asymmetric Flexible MXene-Reduced Graphene Oxide Micro-Supercapacitor. Advanced Electronic Materials: 1700339. Available: http://dx.doi.org/10.1002/aelm.201700339.

Acknowledgements
The authors acknowledge Kathleen Maleski for designing the mask structure with AutoCAD and Bilen Akuzum for laser cutting of Kapton sheets. The authors also acknowledge Leah Clark for the schematic design. Material synthesis and electrochemical characterization work of M.A. and K.L.V.A. were funded by the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Research reported in this publication was partially supported by King Abdullah University of Science and Technology (KAUST). C.C. was supported by the Erasmus Mundus joint master program, Materials for Energy Storage and Conversion (M.E.S.C.). A.M.N-S. was supported by CIC energiGUNE, the Basque Government Scholarship for predoctoral formation (PRE_2015_2_0096) and the Egonlabur Traveling Grant (EP_2016_1_0030). XRD and SEM were performed at the Centralized Research Facilities (CRF) at Drexel University.

Publisher
Wiley

Journal
Advanced Electronic Materials

DOI
10.1002/aelm.201700339

Additional Links
http://onlinelibrary.wiley.com/doi/10.1002/aelm.201700339/full

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