Limits...
From Soybean residue to advanced supercapacitors.

Ferrero GA, Fuertes AB, Sevilla M - Sci Rep (2015)

Bottom Line: Supercapacitor technology is an extremely timely area of research with fierce international competition to develop cost-effective, environmentally friendlier EC electrode materials that have real world application.Interestingly, when Li2SO4 is used, the voltage window is extended up to 1.7 V (in contrast to 1.1 V in H2SO4).Thus, the amount of energy stored is increased by 50% compared to H2SO4 electrolyte, enabling this environmentally sound Li2SO4-based supercapacitor to deliver ~12 Wh kg(-1) at a high power density of ~2 kW kg(-1).

View Article: PubMed Central - PubMed

Affiliation: Instituto Nacional del Carbón (CSIC), P.O. Box 73, Oviedo 33080, Spain.

ABSTRACT
Supercapacitor technology is an extremely timely area of research with fierce international competition to develop cost-effective, environmentally friendlier EC electrode materials that have real world application. Herein, nitrogen-doped carbons with large specific surface area, optimized micropore structure and surface chemistry have been prepared by means of an environmentally sound hydrothermal carbonization process using defatted soybean (i.e., Soybean meal), a widely available and cost-effective protein-rich biomass, as precursor followed by a chemical activation step. When tested as supercapacitor electrodes in aqueous electrolytes (i.e. H2SO4 and Li2SO4), they demonstrate excellent capacitive performance and robustness, with high values of specific capacitance in both gravimetric (250-260 and 176 F g(-1) in H2SO4 and Li2SO4 respectively) and volumetric (150-210 and 102 F cm(-3) in H2SO4 and Li2SO4 respectively) units, and remarkable rate capability (>60% capacitance retention at 20 A g(-1) in both media). Interestingly, when Li2SO4 is used, the voltage window is extended up to 1.7 V (in contrast to 1.1 V in H2SO4). Thus, the amount of energy stored is increased by 50% compared to H2SO4 electrolyte, enabling this environmentally sound Li2SO4-based supercapacitor to deliver ~12 Wh kg(-1) at a high power density of ~2 kW kg(-1).

No MeSH data available.


Related in: MedlinePlus

(a) XPS high resolution N 1s spectra of the porous carbon samples and (b) scheme of the different nitrogen binding motifs identified in the porous carbons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4645100&req=5

f3: (a) XPS high resolution N 1s spectra of the porous carbon samples and (b) scheme of the different nitrogen binding motifs identified in the porous carbons.

Mentions: The bulk chemical composition of defatted soybean and the dSb-derived porous carbons deduced by elemental analysis is shown in Table 1. It can be seen that the activated carbons have a large oxygen content, which decreases with the activation temperature from ~25% at 600 °C to ~14% at 800 °C. More importantly, N-doping is confirmed by values in the range of 1.6–4%. Furthermore, the nitrogen heteroatoms are uniformly distributed throughout the N-doped particles, as can be deduced from the elemental energy-dispersive X-ray (EDX) mapping images in Supplementary Fig. S2b-c online. The chemical nature of the nitrogen groups was examined by XPS analysis. High-resolution N 1s spectra are displayed in Fig. 3a and the relative contribution of each moiety is listed in Supplementary Table S1 online. The samples obtained at T > 600°C exhibit three main peaks that can be assigned to pyridinic-N (398.6 ± 0.2 eV), pyrrolic-/pyridonic-N (400.4 ± 0.2 eV) and quaternary-N (401.1 ± 0.2 eV), and a minor peak that is attributed to pyridine-N-oxides (402.9 ± 0.3 eV)3435. The identified binding motifs are depicted in Fig. 3b. A clear decrease in the number of less stable species, i.e. pyrrolic-/pyridonic-N, and an increase in the amount of more stable ones, i.e. pyridinic- and quaternary-N, is recorded with the rise in synthesis temperature. Thus, AS-800 contains almost half of the content of pyrrolic nitrogen of AS-600. It has been shown that pseudocapacitive interactions take place on the negatively charged pyrrolic-N and pyridinic-N groups, while the positive charge on quaternary-N and pyridine-N-oxides favours the electron transfer through the carbon, enhancing the conductivity of the carbon materials3637. The removal of oxygen functionalities, coupled to the increase in N-Q and N-X and carbon ordering with the rise in carbonization temperature, explains the enhancement of electronic conductivity as the synthesis temperature increases (see Table 1).


From Soybean residue to advanced supercapacitors.

Ferrero GA, Fuertes AB, Sevilla M - Sci Rep (2015)

(a) XPS high resolution N 1s spectra of the porous carbon samples and (b) scheme of the different nitrogen binding motifs identified in the porous carbons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645100&req=5

f3: (a) XPS high resolution N 1s spectra of the porous carbon samples and (b) scheme of the different nitrogen binding motifs identified in the porous carbons.
Mentions: The bulk chemical composition of defatted soybean and the dSb-derived porous carbons deduced by elemental analysis is shown in Table 1. It can be seen that the activated carbons have a large oxygen content, which decreases with the activation temperature from ~25% at 600 °C to ~14% at 800 °C. More importantly, N-doping is confirmed by values in the range of 1.6–4%. Furthermore, the nitrogen heteroatoms are uniformly distributed throughout the N-doped particles, as can be deduced from the elemental energy-dispersive X-ray (EDX) mapping images in Supplementary Fig. S2b-c online. The chemical nature of the nitrogen groups was examined by XPS analysis. High-resolution N 1s spectra are displayed in Fig. 3a and the relative contribution of each moiety is listed in Supplementary Table S1 online. The samples obtained at T > 600°C exhibit three main peaks that can be assigned to pyridinic-N (398.6 ± 0.2 eV), pyrrolic-/pyridonic-N (400.4 ± 0.2 eV) and quaternary-N (401.1 ± 0.2 eV), and a minor peak that is attributed to pyridine-N-oxides (402.9 ± 0.3 eV)3435. The identified binding motifs are depicted in Fig. 3b. A clear decrease in the number of less stable species, i.e. pyrrolic-/pyridonic-N, and an increase in the amount of more stable ones, i.e. pyridinic- and quaternary-N, is recorded with the rise in synthesis temperature. Thus, AS-800 contains almost half of the content of pyrrolic nitrogen of AS-600. It has been shown that pseudocapacitive interactions take place on the negatively charged pyrrolic-N and pyridinic-N groups, while the positive charge on quaternary-N and pyridine-N-oxides favours the electron transfer through the carbon, enhancing the conductivity of the carbon materials3637. The removal of oxygen functionalities, coupled to the increase in N-Q and N-X and carbon ordering with the rise in carbonization temperature, explains the enhancement of electronic conductivity as the synthesis temperature increases (see Table 1).

Bottom Line: Supercapacitor technology is an extremely timely area of research with fierce international competition to develop cost-effective, environmentally friendlier EC electrode materials that have real world application.Interestingly, when Li2SO4 is used, the voltage window is extended up to 1.7 V (in contrast to 1.1 V in H2SO4).Thus, the amount of energy stored is increased by 50% compared to H2SO4 electrolyte, enabling this environmentally sound Li2SO4-based supercapacitor to deliver ~12 Wh kg(-1) at a high power density of ~2 kW kg(-1).

View Article: PubMed Central - PubMed

Affiliation: Instituto Nacional del Carbón (CSIC), P.O. Box 73, Oviedo 33080, Spain.

ABSTRACT
Supercapacitor technology is an extremely timely area of research with fierce international competition to develop cost-effective, environmentally friendlier EC electrode materials that have real world application. Herein, nitrogen-doped carbons with large specific surface area, optimized micropore structure and surface chemistry have been prepared by means of an environmentally sound hydrothermal carbonization process using defatted soybean (i.e., Soybean meal), a widely available and cost-effective protein-rich biomass, as precursor followed by a chemical activation step. When tested as supercapacitor electrodes in aqueous electrolytes (i.e. H2SO4 and Li2SO4), they demonstrate excellent capacitive performance and robustness, with high values of specific capacitance in both gravimetric (250-260 and 176 F g(-1) in H2SO4 and Li2SO4 respectively) and volumetric (150-210 and 102 F cm(-3) in H2SO4 and Li2SO4 respectively) units, and remarkable rate capability (>60% capacitance retention at 20 A g(-1) in both media). Interestingly, when Li2SO4 is used, the voltage window is extended up to 1.7 V (in contrast to 1.1 V in H2SO4). Thus, the amount of energy stored is increased by 50% compared to H2SO4 electrolyte, enabling this environmentally sound Li2SO4-based supercapacitor to deliver ~12 Wh kg(-1) at a high power density of ~2 kW kg(-1).

No MeSH data available.


Related in: MedlinePlus