Nano Carbon/Vertical Graphene/MnO₂ Nanosheets Composite Particles for High‐Performance Supercapacitors

Abstract

Compounding carbon substrate materials with pseudocapacitive materials is an important strategy for making high-performance supercapacitor materials. Nano carbon black (CB) is widely used as the conductive additive in energy storage devices owing to its low cost, high conductivity, good spreadability, and excellent ability of adsorbing electrolyte, reducing the binder consumption, adjusting the pore size and fraction of the electrode, and high-voltage operation. However, very little attention has been paid to applying CB as the substrate materials for producing composite active materials. Herein, a surface-modified CB is developed by growing vertical graphene nanosheets on the surface of CB by chemical vapor deposition. After growing MnO 2 nanosheets on the modified CB, the obtained nanocomposites deliver high specific capacitance, rate performance, and cycling stability. The assembled symmetric supercapacitor obtains a high energy density of 54 Wh kg À1 at a power density of 181 W kg À1 . Systematic experimental research reveals the superior performance benefits from the surface modification of CB by vertical graphene nanosheets, which improves the electrical conductivity, thermal stability, and pore structure of the whole electrodes. This method is of great promise for the development of new materials for highperformance supercapacitors.

A Conjugately Configured Supercapacitor with Suppressed Self-Discharge by Coupling Pairs of Presodiated Manganese Oxides

“…The crystal structure of MnO 2 is known for significantly influencing its pseudocapacitive performance. − So, we prepared MnO 2 with various phases as samples to study suitable candidate materials. The XRD patterns given in Figure a indicate that the prepared MnO 2 samples have desired phases and high purity.…”

Stabilizing Semi-Crystalline Phase in CsPbBr3 Nanocrystals for Supercapacitor Application

“…Carbon allotropes with high porosity and surface area have traditionally been used as EDLC electrodes because of their high electrical conductivity. 1,27,28 Adsorption of negative ions from the electrolyte on the positively charged electrode creates a double layer. The high-power density of these devices is due to the rapid diffusion of ions from the electrolyte to the electrode surface.…”

In Situ S‐Doped Graphene Film using NaHSO3 as Sulfur Source for High‐Performance Flexible Supercapacitors

“…[ 3–5 ] As for electrode material, plentiful research efforts have been mainly devoted to the exploration of various carbonaceous materials including carbon black, carbon nanotubes, carbon nanofibers, and graphene. [ 6–11 ] Among them, graphene is regarded as one of the most desirable electrode materials applied in electrochemical energy storage devices, owing to its inherent physicochemical properties, such as excellent flexibility, electrical conductivity, stable chemical performance, and outstanding cycle stability. [ 12–14 ]…”

“…[3][4][5] As for electrode material, plentiful research efforts have been mainly devoted to the exploration of various carbonaceous materials including carbon black, carbon nanotubes, carbon nanofibers, and graphene. [6][7][8][9][10][11] Among them, graphene is regarded as one of the most desirable electrode materials applied in electrochemical energy storage devices, owing to its inherent physicochemical properties, such as excellent flexibility, electrical conductivity, stable chemical performance, and outstanding cycle stability. [12][13][14] However, graphene sheets are prone to agglomeration because of the strong π-π interactions and van der Waals force between graphene sheets, which greatly reduce their effective specific surface area, electrical conductivity, and electrochemical performance.…”