Ultrathin Two-Dimensional MnO₂/Graphene Hybrid Nanostructures for High-Performance, Flexible Planar Supercapacitors

Abstract

Planar supercapacitors have recently attracted much attention owing to their unique and advantageous design for 2D nanomaterials based energy storage devices. However, improving the electrochemical performance of planar supercapacitors still remains a great challenge. Here we report for the first time a novel, high-performance in-plane supercapacitor based on hybrid nanostructures of quasi-2D ultrathin MnO2/graphene nanosheets. Specifically, the planar structures based on the δ-MnO2 nanosheets integrated on graphene sheets not only introduce more electrochemically active surfaces for absorption/desorption of electrolyte ions, but also bring additional interfaces at the hybridized interlayer areas to facilitate charge transport during charging/discharging processes. The unique structural design for planar supercapacitors enables great performance enhancements compared to graphene-only devices, exhibiting high specific capacitances of 267 F/g at current density of 0.2 A/g and 208 F/g at 10 A/g and excellent rate capability and cycling stability with capacitance retention of 92% after 7000 charge/discharge cycles. Moreover, the high planar malleability of planar supercapacitors makes possible superior flexibility and robust cyclability, yielding capacitance retention over 90% after 1000 times of folding/unfolding. Ultrathin 2D nanomaterials represent a promising material platform to realize highly flexible planar energy storage devices as the power back-ups for stretchable/flexible electronic devices.

Two-dimensional vanadyl phosphate ultrathin nanosheets for high energy density and flexible pseudocapacitors

“…S13). Employing pseudocapacitor in-plane, micro-electrodes can potentially further enhance the performance of 2D hybrid VOPO4/graphene thin film, as it could mitigate the issues from contact resistance and electrolyte ions diffusion in the case of much higher mass loading 10,37 . Furthermore, the discharge voltage up to B1.0 V is a significant step for constructing high energy density supercapacitors.…”

Hyaluronic acid-functionalized bismuth oxide nanoparticles for computed tomography imaging-guided radiotherapy of tumor

“…[7][8][9][10][11][12] Additionally, nanoparticles (NPs) could be ideal candidates for accurate tumor-targeting imaging to locate tumors because of their prolonged circulation time, selective accumulation in tumors by the enhanced permeability and retention effect, and active targeting through conjugating with folic acid, antibodies, peptides, or hyaluronic acid (HA). 13 In addition, the X-ray dose of the surrounding tissue will be greatly reduced, and higher dose can be concentrated at the tumor region containing NPs.…”

Engineering Graphenes from the Nano- to the Macroscale for Electrochemical Energy Storage

“…and 208 F g −1 at 10 Ag −1 . This film also showed excellent rate capability and cycling stability with a high capacitance retention (92%) after 7000 charge/discharge cycles [67]. Wu et al proposed a strategy of utilizing the strong coupling and synergistic effect of graphene-conducting polymer nanosheets and electrochemically exfoliated graphene to construct a micrometer-thick graphene-conducting polymer hybrid film, which had a high density of 1.67 g cm −3 and an excellent electronic conductivity of 2120 S cm −1 , leading to an ultrahigh areal capacitance of 368 mF cm −2 and a volumetric capacitance of 736 F cm −3 [68].…”