Heteroatom-doped porous carbon with tunable pore structure and high specific surface area for high performance supercapacitors

Abstract

Biomass-derived porous carbons with very high specific surface area (SSA) and heteroatom-doping are important for obtaining high performance supercapacitor. In this study, we report a simple and straightforward strategy, which involves the efficient and exothermic pyrolysis of Mg/K/Mg•K-nitrate-urea-cellulose mixture with subsequent high temperature carbonization and washing treatment, to produce N-doped porous carbon with tunable pore structure. The vigorous exothermic pyrolysis of Mg/K/Mg•K-nitrate-urea-cellulose induces the formation of large macropores. The subsequent high temperature carbonization and washing treatments remove Mg,K compounds and facilitate the creation of numerous micro and mesopores. The pore size distribution of the obtained carbon is quite dependent on the Mg•K ratio in the precursors. In this manner, the three-dimensional hierarchical porous carbon with SSA larger than 2700 m 2 g -1 is obtained. The obtained porous carbon as the electrodes for supercapacitor in two-electrode measurement shows high specific capacitance (279 F g -1 at 1 A g -1 in a 6 M KOH electrolyte), excellent cycling stability (larger than 89% capacitance retention after 10,000 cycles at 2 A g -1 ) and good rate capability (235 F g -1 at even 30 A g -1 ). These results indicate that biomass cellulose-derived heteroatom-doped hierarchical porous carbon is a promising material for supercapacitor.

Superior Multifunctional Activity of Nanoporous Carbons with Widely Tunable Porosity: Enhanced Storage Capacities for Carbon‐Dioxide, Hydrogen, Water, and Electric Charge

“…PMCs/CMCs also show excellent rate performance through their capacitance retention with respect to the increased current loads. As per comparative data represented in Figure k, these samples with SSA BET of ≈2500 m 2 g −1 exhibit equally good rate and capacity performance with respect to the large number of samples reported in the literature . For example, micro‐/mesoporous graphitic carbon, with SSA BET of over 4000 m 2 g −1 , shows a capacitance value of just 225 F g −1 (and C SSA of 5.5 µF cm −2 ) at 0.5 A g −1 , far less than 320 or 270 F g −1 for the PMC450 or UMC450 with SSA BET of 2500 or 1620 m 2 g −1 .…”

“…The aqueous EDLC capacities between 300–320 F g −1 at 500 mA g −1 in our PMCs/CMCs with specific porosity characteristics outperform many of the other high surface area carbons (Figures g and f, and Figures S9 and 10 and Table S1 in Supporting Information) . This clearly indicates that most of the samples with ultrahigh porosity, for example, the samples with SSA BET greater than 2500 m 2 g −1 show reduced tendency in their EDLC values, and associated areal capacities are lower than 10 µF cm −2 (Figure h).…”

“…Interestingly, all the adsorptive capacities for EDCL, CO 2 , H 2 and H 2 O vary in a similar manner, linearly with respect to the SSA BET or pore volume (Figures and g). Here it is interesting to note that with respect to the SSA BET the UMCs show relatively high gravimetric as well as areal (surface area normalized capacitance, C SSA ) EDLC capacity when compared to numerous other high surface area carbons in the literature (Figure g–i) . The EDLC capacities (deduced at current loads of 0.5–1.0 A g −1 ) of the high surface area carbons from literature are summarily presented in Figure g (Table and Table S1 in Supporting Information).…”

“…Such materials exhibit a wide range of porosities, with ultrahigh surface area being particularly targeted . These high porosities are achieved by simultaneously increasing the pore widths across several nanometers—commonly defined to be: microporosity, mesoporosity, and macroporosity respectively for pore widths of ≤2 nm, (2–50) nm, and ≥50 nm.…”

Fatsia Japonica-Derived Hierarchical Porous Carbon for Supercapacitors With High Energy Density and Long Cycle Life

“…Heteroatom doping is one of the common strategies for preparing high-performance supercapacitor carbon materials (Hou et al, 2018;Lee et al, 2018;Kim et al, 2019;Wu et al, 2019). Seeds are rich in a variety of active ingredients, so it is inferred SCHEME 1 | Schematic illustration of the fabrication process of HPCs.…”