Regulating Capacitive Performance of Monolithic Carbon Sponges by Balancing Heteroatom Content, Surface Area and Graphitization Degree

Abstract

Monolithic electrodes show a great advantage in energy storage devices. Nitrogen/oxygen co-doped carbons sponges (NOCSs) prepared from carbonized melamine foams are directly applied as the supercapacitor electrodes without any additives and binders. The influence of carbonization temperatures from 650 to 950°C on the heteroatom (N and O) content, surface area, graphitization degree, and capacitor performance of carbon sponges are systematically investigated, and it is found that NOCS-850 delivers a better overall capacitive properties for its balanced heteroatom content, surface area, and graphitization degree. It possess specific capacitances of 338 F g À 1 at a scan rate of 1.0 mV s À 1 and 168.3 F g À 1 at a current density of 0.5 A g À 1 in 1.0 M H 2 SO 4. After 5000 cycles of repeated charging/discharging process, the capacitance retention remains 107%. When being assembled into an all-solid-state supercapacitor, the NOCS-850 has a energy density of 5.38 Wh kg À 1 at a power density of 233 W kg À 1. A red light-emitting diode can be successfully lighted by three connected all-solid-state supercapacitors of NOCS-850, illustrating its potential application in energy storage field.

KOH Chemical-Activated Porous Carbon Sponges for Monolithic Supercapacitor Electrodes

“…Figure a reveals the presence of carbon, nitrogen, and oxygen in all samples, confirming the characteristic of N/O co-doing in carbon materials. The peak-fitting of the C 1s spectrum reveals four peaks at 284.7, 285.5, 286.3, and 287.5 eV (Figure b) corresponding to C–C/CC, CN, C–O, and CO, respectively. , According to the N 1s XPS spectrum (Figure c), the doped nitrogen atoms exist in the forms of pyridinic (N-6, 398.4 eV), pyrrolic (N-5, 400.0 eV), quaternary (N-Q, 401.1 eV), and oxidized nitrogen (N-X, 403.0 eV). , The deconvolution of the O 1s XPS spectrum (Figure d) confirms the presence of four oxygen-containing species, which are referred to as O–I/II/III/IV. The O–I species with a low binding energy of 531.0 eV is quinone-type oxygen, and the O–II/III species at 532.3 and 533.5 eV correspond to the phenol-/ether-type oxygen, respectively.…”

“…The peak-fitting of the C 1s spectrum reveals four peaks at 284.7, 285.5, 286.3, and 287.5 eV (Figure 3b) corresponding to C−C/CC, C N, C−O, and CO, respectively. 23,25 According to the N 1s XPS spectrum (Figure 3c), the doped nitrogen atoms exist in the forms of pyridinic (N-6, 398.4 eV), pyrrolic (N-5, 400.0 eV), quaternary (N-Q, 401.1 eV), and oxidized nitrogen (N-X, 403.0 eV). 29,30 The deconvolution of the O 1s XPS spectrum (Figure 3d) confirms the presence of four oxygen-containing species, which are referred to as O−I/II/III/IV.…”

“…Therefore, it is urgent to develop a monolithic carbon-based electrode without using any additives. It is found that melamine sponge, a commercial formaldehyde–melamine resin, has a three-dimensional (3D) network structure. , After carbonization, the derived carbon materials well retain the 3D inner architecture as well as the monolithic outer structure. ,, Moreover, the doped heteroatoms can also contribute extra PC by surface redox reactions with electrolytes. , The free-standing porous structure along with abundant heteroatoms make melamine sponge a promising precursor for the monolithic electrode.…”

“…21,22 After carbonization, the derived carbon materials well retain the 3D inner architecture as well as the monolithic outer structure. 14,23,24 Moreover, the doped heteroatoms can also contribute extra PC by surface redox reactions with electrolytes. 22,25 The free-standing porous structure along with abundant heteroatoms make melamine sponge a promising precursor for the monolithic electrode.…”

Nitrogen and oxygen Co-doped porous carbon derived from yam waste for high-performance supercapacitors

“…Compared with single heteroatom doping, N and O co-doping enhanced the overall electrochemical properties of materials through a synergistic effect. 52,53 3.2 Electrochemical properties in the three-electrode system CV, GCD, and electrochemical impedance spectroscopy (EIS) techniques were applied to evaluate the electrochemical performance of the YPC-n samples in 6 M KOH in a threeelectrode system at 25 C. The CV proles of the YPC-n electrodes (Fig. 6a and S5a †) were measured at scan rates of 10 mV s À1 between À1.0 and 0 V. As observed, the CV curves generally present a symmetrical rectangular shape, which indicates that the electrochemical reaction is dominated by the EDLC.…”