3D Macroporous Graphene Frameworks for Supercapacitors with High Energy and Power Densities

Abstract

In order to develop energy storage devices with high power and energy densities, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate high-performance supercapacitors by building a three-dimensional (3D) macroporous structure that consists of chemically modified graphene (CMG). These 3D macroporous electrodes, namely, embossed-CMG (e-CMG) films, were fabricated by using polystyrene colloidal particles as a sacrificial template. Furthermore, for further capacitance boost, a thin layer of MnO(2) was additionally deposited onto e-CMG. The porous graphene structure with a large surface area facilitates fast ionic transport within the electrode while preserving decent electronic conductivity and thus endows MnO(2)/e-CMG composite electrodes with excellent electrochemical properties such as a specific capacitance of 389 F/g at 1 A/g and 97.7% capacitance retention upon a current increase to 35 A/g. Moreover, when the MnO(2)/e-CMG composite electrode was asymmetrically assembled with an e-CMG electrode, the assembled full cell shows remarkable cell performance: energy density of 44 Wh/kg, power density of 25 kW/kg, and excellent cycle life.

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

“…The vertical line at low frequency indicates the diffusive behavior of electrolyte ions in the electrode, [8] and the more vertical line of GQD/MnO 2 -3 than others suggests lower ion diffusion resistance and faster ion diffusion behavior. [45] The slope of ≈45° lines reveals the diffusion behavior on the electrolyte/ electrode interface. [46] In the high-frequency region, the diameter of semicircle denotes charge transfer resistance (R ct ).…”

Materials Design and System Construction for Conventional and New‐Concept Supercapacitors

“…For example, Huh et al build three‐dimensional graphene films by using polystyrene colloidal particles as a sacrificial template 137. Zhang et al obtained porous three‐dimensional graphene‐based bulk materials through efficient and industrially scalable approach 138.…”

Morphological characterization and impedance spectroscopy study of porous 3D carbons based on graphene foam-PVA/phenol-formaldehyde resin composite as an electrode material for supercapacitors

“…This indicates that porous electrodes based on these activated materials have excellent rate performance and a rapid ion transport mechanism. 36 The cell capacitance is calculated from the discharge curve using equation 1:…”