Nitrogen Codoped Unique Carbon with 0.4 nm Ultra‐Micropores for Ultrahigh Areal Capacitance Supercapacitors

Abstract

A full understanding of ion transport in porous carbon electrodes is essential for achieving effective energy storage in their applications as electrochemical supercapacitors. It is generally accepted that pores in the size range below 0.5 nm are inaccessible to electrolyte ions and lower the capacitance of carbon materials. Here, nitrogen-doped carbon with ultra-micropores smaller than 0.4 nm with a narrow size distribution, which represents the first example of electrode materials made entirely from ultra-microporous carbon, is prepared. An in situ electrochemical quartz crystal microbalance technique to study the effects of the ultra-micropores on charge storage in supercapacitors is used. It is found that ultra-micropores smaller than 0.4 nm are accessible to small electrolyte ions, and the area capacitance of obtained sample reaches the ultrahigh value of 330 µF cm , significantly higher than that of previously reported carbon-based materials. The findings provide a better understanding of the correlation between ultra-micropore structure and capacitance and open new avenues for design and development of carbon materials for the next generation of high energy density supercapacitors.

Space‐Confined Synthesis of ZIF‐67 Nanoparticles in Hollow Carbon Nanospheres for CO2 Adsorption

“…The key to success of HCSs in various applications is based on the availability of precisely controlled diameter and shell thickness, surface chemistry, and dispersibility in media. Numerous investigations have been devoted to the synthesis of porous carbon spheres via various strategies, including hard or soft‐templating method, emulsion self‐assembly process, and stöber‐based routes . Among the studies reported, many have focused on the preparation of hollow structural units with tunable sizes.…”

Template‐Induced Self‐Activation Route for Hierarchical Porous Carbon Derived from Interpenetrating Polymer Networks as Electrode Material for Supercapacitors

“…The smaller semicircle of HPC-1 than those of the other samples at highfrequency region of the EIS spectra indicates its much better electrochemical capacitive properties, lower charge transfer resistance and diffusion resistance. [57] The slope at low fre-quency becomes much steeper for HPC-1, confirming its higher capacitive behavior. The relationship between the specific capacitance and the loading current density of the samples are plotted in Figure 6e.…”

“…hold that the semicircle loop was ascribed to the resistance between active material particles and the contact resistance at the current collector/active material. The smaller semicircle of HPC‐1 than those of the other samples at high‐frequency region of the EIS spectra indicates its much better electrochemical capacitive properties, lower charge transfer resistance and diffusion resistance . The slope at low frequency becomes much steeper for HPC‐1, confirming its higher capacitive behavior.…”

Electrochemical Supercapacitors: From Mechanism Understanding to Multifunctional Applications

“…[ 35 ] Mass change recorded by EQCM revealed that the nanopores in N‐doped carbon microspheres (pore size < 0.4 nm) are accessible for both cations and anions, harnessing high capacitance of 330 µF cm −2 (normalized to surface area). [ 36 ] However, linear gravimetric quantification is only conclusive when no dissipation factor (the ratio of full resonance width peak to the related resonance frequency) variation is involved. [ 14 ] In this case, hydrodynamic spectroscopy (EQCM‐D) needs to be incorporated, which can operate under different overtones enabling different penetration depth.…”