Composite of manganese dioxide impregnated in porous hollow carbon spheres for flexible asymmetric solid‐state supercapacitors

Abstract

Compared with symmetric supercapacitors, asymmetric supercapacitors are been widely applied in energy storage devices because of delivering an impressible energy density. Herein, a simple temple strategy was used to fabricate the porous hollow carbon spheres (PHCS) with high specific surface area of 793 m 2 g −1 , large pore volume of 1.0 cm 3 g −1 and pore size distribution from micropores to mesopores, serving as the capacitive electrodes of asymmetric supercapacitors. Subsequently, manganese dioxide (MnO 2 ) was impregnated into the PHCS to form a faradic electrode with a promising performance, owing to a synergistic effect between high capacity MnO 2 and conductive PHCS. Furthermore, the flexible asymmetric solid-state devices were constructed with PHCS anode, PHCS@MnO 2 cathode, and PVA/LiCl electrolyte, extending a voltage window up to 1.8 V. The extensive voltage window would lead to an increased energy density. In our case, the flexible asymmetric sandwich exhibit excellent electrochemical performance in terms of a high energy density capacity of 26.5 W·h kg −1 (900 W kg −1 ) and superior cycling performance (10 000 cycles). Therefore, the developed strategy provides a strategy to achieve the PHCS-based composites for the application in the asymmetric solid-state supercapacitors, which will enable a widely field of flexible energy storage devices.

Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

“…Rajeswari et al report that ZnO cyclic voltammetry (CV) polt is quasi‐rectangular shape within current and potential axes without an obvious redox peak because ZnO is not a good pseudocapacitive. Wang et al synthesized cobalt oxide encamped with carbon sphere and obtained an awesome energy density of 900 W kg −1 and superior cycling stability of 10 000 cycles, this was possible due to addition of carbon derivative.…”

Hierarchitecture Co 2 (OH) 3 Cl@FeCo 2 O 4 composite as a novel and high‐performance electrode material applied in supercapacitor

“…Among electrode materials, transition metal oxides (TMOs) show the higher performance ascribed to their complex valence states, while carbon materials usually shows a lower performance. It can reveals promising prospects of TMOs in supercapacitors application …”

“…It can reveals promising prospects of TMOs in supercapacitors application. [16][17][18][19][20][21][22] Among TMOs, RuO 2 has used as SCs electrode materials because of its highest capacity and ideal capacitive behavior, but the practical application has been restricted by its expensive costs and high toxicity. 23,24 Researchers are focusing on spinel structure MCo 2 O 4 (M = Fe, Ni, Zn, Mn) ascribed to their low cost and high electrochemical performances used as supercapacitor electrode.…”

Synthesis of porous flower‐like Ni‐Co‐Mo‐S nanostructures on Ni foam for battery‐supercapacitor hybrid devices

“…Supercapacitors (SCs) were regarded as one of the most promising energy storage devices because of their superior power density, fast charge/discharge process, and ultralong cycle stability . But the practical applications of SCs were dramatically limited by the low energy density . Currently, battery‐supercapacitor hybrid (BSH) device composed of a capacitive electrode and a battery‐type electrode was used to increase energy density .…”

“…[1][2][3][4][5][6] But the practical applications of SCs were dramatically limited by the low energy density. [7][8][9] Currently, battery-supercapacitor hybrid (BSH) device composed of a capacitive electrode and a battery-type electrode was used to increase energy density. [10][11][12][13] In general, the working voltage of the BSH device could be enlarged by utilizing different potential windows of two electrodes.…”