High‐Performance Asymmetric Supercapacitors Based on Multilayer MnO₂/Graphene Oxide Nanoflakes and Hierarchical Porous Carbon with Enhanced Cycling Stability

Abstract

In this work, MnO(2)/GO (graphene oxide) composites with novel multilayer nanoflake structure, and a carbon material derived from Artemia cyst shell with genetic 3D hierarchical porous structure (HPC), are prepared. An asymmetric supercapacitor has been fabricated using MnO(2)/GO as positive electrode and HPC as negative electrode material. Because of their unique structures, both MnO(2)/GO composites and HPC exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high voltage range of 0-2 V in aqueous electrolyte, which exhibits maximum energy density of 46.7 Wh kg(-1) at a power density of 100 W kg(-1) and remains 18.9 Wh kg(-1) at 2000 W kg(-1). Additionally, such device also shows superior long cycle life along with ∼100% capacitance retention after 1000 cycles and ∼93% after 4000 cycles.

Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

“…[22] The detailed discussion is shown in Figure S3 (Supporting Information). The peak intensity ratio between the disorder-induced D peak and sp 2 planes of GQDs are decreased after prolonging the deposition time of PECVD, which is mainly attributed to the edges of GQDs with a low stability that are etched away through growth of GQDs and finally become regular and straighter.…”

“…[8,9] Among TMO materials, MnO 2 is one of the most potential materials for supercapacitors due to its high theoretical specific capacitance, environmental friendliness, and the high practical voltage window (about 1 V). [2] However, it has suffered from intrinsically low conductivity and specific surface area, which severely restrict its further development in practical application of supercapacitors. In this regard, integrating nanostructured MnO 2 and conductive carbon materials to fabricate novel hybrid nanostructures is a plausible solution to overcome this obstacle.…”

“…Supercapacitors which pose faster charge/discharge rates and higher power density are becoming hot topics of current research worldwide. [1][2][3][4] However, the practical application of supercapacitors has long been a challenge because of their limited energy density. Thus, focused on the voltage undertaken by structural modification through Na + deintercalation and intercalation and found that the potential of the Mn 3 O 4 can be extended to 1.3 V through this method.…”

α-Fe2O3-Based Core-Shell-Nanorod–Structured Positiveand Negative Electrodes for a High-Performance α-Fe2O3/C//α-Fe2O3/MnOxAsymmetric Supercapacitor

“…8 The energy density of supercapacitors can be enhanced by increasing their capacitance as well as their operating-potential window, which can be achieved more easily with asymmetric supercapacitors (ASCs) than with the symmetric supercapacitors (SSCs) since, with suitable combination of positive and negative electrode materials, the operational potential window as high as 2 V has been achieved even with aqueous electrolytes. 6,[9][10][11][12][13][14] In recent years, efforts have been expended to explore several ASCs with different electrode materials based on redox-active transition-metal oxides, like RuO 2 , 15 SnO 2 , 23 etc., which are not commercially viable owing to their high cost and environmental incompatibility. Accordingly, there is need to explore certain alternative combinations of positive and negative electrode materials to design a high-performance, cost-effective and environmentally benign ASC.…”

High Specific Capacitance of Polyaniline/Mesoporous Manganese Dioxide Composite Using KI-H2SO4 Electrolyte

“…The polyaniline (PANI) could act as an active electrode material for a super-capacitor because of controllable electrical conductivity, high environmental stability, and capacitance performance [30][31][32]. Even though the theoretical specific capacitance of separate manganese dioxide can reach 1370 F/g [33], whereas the practical specific capacitance still keeps several hundred farads which need to be improved by researchers. The PANI also has higher specific capacitance, but the poor mechanical property seriously limits its practical applications.…”