Mechanisms of Porous Carbon‐based Supercapacitors

Abstract

Supercapacitors are electrochemical energy storage devices that function by the adsorption of ions from an electrolyte onto an electrode with a high surface area. Due to the advantages such as high‐power density and a longer life span, supercapacitors bearing nanoscale porous carbon‐based electrodes, have gained special interest. The high specific surface area of nano‐scale porous carbon‐based electrodes could substantially increase the energy density of supercapacitors. Here we review the research pertaining to the energy storage of supercapacitors and the mechanism regulating the microscopic energy storage within nanopores. The advantages and challenges of various in situ characterization techniques and simulation techniques in the energy storage mechanism were discussed. The effective combination of in situ characterization techniques and computer simulations has been highlighted since it provides a useful means to understand the intrinsic properties of the electrode/electrolyte interface and various physicochemical reactions that take place during charging/discharging. This understanding is valuable for the design and development of next‐generation supercapacitors with the high power density and high energy density.

N and P Co‐doped Green Waste Derived Hierarchical Porous Carbon as a Supercapacitor Electrode for Energy Storage: Electrolyte Effects

“…The PW larger mesopore volume made it easier for the solvated large‐sized cationic electrolyte (K + /Na + ) ions to enter the carbon pore structure [3,42,43] or become adsorbed in the outer Helmholtz layer of the electrode surface [44] . Figure 4b shows the CV curves of NPW in various electrolytes at a scan rate of 25–200 mV s −1 .…”

“…The PW larger mesopore volume made it easier for the solvated large-sized cationic electrolyte (K + /Na + ) ions to enter the carbon pore structure [3,42,43] or become adsorbed in the outer Helmholtz layer of the electrode surface. [44] Figure 4b shows the CV curves of NPW in various electrolytes at a scan rate of 25-200 mV s À 1 . Even at a high scan rate of 200 mV s À 1 , NPW maintained a nearly quasi-rectangular shape, demonstrating good rate performance due to improved surface and physicochemical properties.…”

Dual function composite fibers of cellulose with activated carbon aerogel and carbide derived carbon

“…The carbon materials of principal interest in cellulose have usually been the carbon nanotubes 18 or reduced graphene oxides 19 due to their good electric conductivity. Carbide‐derived carbon (CDC) 20 is a widely used electrode material in supercapacitors, 20 its etching temperature determines a narrow pore size distribution, typically in range of 0.6–1.1 nm, leading to specific capacitances in the range of 90–150 F g −1 in organic electrolytes 21 . Activated carbon aerogels (ACA) 22 are another class of carbon materials used in supercapacitors consisting of a synthetic gel that over cross‐linkage, drying and carbonization is turned into a highly porous ultra‐light 3D network, then activated chemically or physically to create more micropores and to increase the specific surface area 23 .…”

“…Carbide-derived carbon (CDC) 20 is a widely used electrode material in supercapacitors, 20 its etching temperature determines a narrow pore size distribution, typically in range of 0.6-1.1 nm, leading to specific capacitances in the range of 90-150 F g À1 in organic electrolytes. 21 Activated carbon aerogels (ACA) 22 are another class of carbon materials used in supercapacitors consisting of a synthetic gel that over cross-linkage, drying and carbonization is turned into a highly porous ultra-light 3D network, then activated chemically or physically to create more micropores and to increase the specific surface area. 23 ACA materials have reached specific capacitance in organic electrolytes 24 up to 152 F g À1 while those made from green sources (coffee grounds) with even smaller pore sizes of 2-4 nm 25 have reached specific capacitance of 220 F g À1 .…”

Effects of Ionic Size and Hydrophobicity on Charging Dynamics at Microporous Pt

“…22 In this case, ions with a charge opposite to that of the electrode surface are excessively present in the nanopores, and ions with the same charge are present in a small amount. This permselectivity has mainly been applied to electrochemical supercapacitors, 23 capacitive deionization, 24 and conductometry. 25,26 The size effect of the ions becomes more pronounced as the pore size decreases.…”