High Performance N‐Doped Carbon Electrodes Obtained via Hydrothermal Carbonization of Macroalgae for Supercapacitor Applications

Abstract

The conversion of bio‐waste into useful porous carbons constitutes a very attractive approach to contribute to the development of sustainable energy economy, even more as they can be used in energy storage devices. Here we report the synthesis of N‐doped carbons from hydrothermal carbonization of macroalgae, Enteromorpha prolifera (EP), followed by a mild KOH activation step. The obtained N‐doped carbons exhibited surface areas of up to ∼2000 m2/g with N‐loadings varied in the range of 1.4∼2.9 at %. By modifying activation temperature, we were able to tune the surface chemistry and porosity, achieving excellent control of their properties. The specific capacitance reached values of up to 200 F/g at 1 A/g in 6 M KOH for the sample obtained at activation temperature of 700 °C (AHC‐700). The symmetric supercapacitor using the sample activated at 800 °C (AHC‐800) as electrodes exhibited the highest cycling stability of the samples studied in this work, with capacitance retention of up to 96 % at 10 A/g, even after 10,000 cycles, constituting the highest reported for biomass‐derived carbon electrodes. These results show the great potential of N‐doped carbons as electrodes for supercapacitors and confirm the excellent electrochemical properties of biomass‐derived carbons in energy storage technologies.

N‐Doped Hierarchical Porous Carbon with Open‐Ended Structure for High‐Performance Supercapacitors

“…A comparison of gravimetric specific capacitance (C g ) of A‐HCS in this work with other N‐doped porous carbons reported in literature (Table S1). Obviously, the specific capacitance of the obtained A‐HCS electrode is much higher or at least comparable to those of most reported N‐containing porous carbon materials ,,,,,…”

Structural Rigging of Lignin Precursors for Customized Porous and Graphene‐Like Carbons towards Enhanced Supercapacitive Performance in Aqueous and Non‐Aqueous Electrolytes

“…By extrapolating the vertical portion to the real axis, the impressive small R ESR of 0.51 and 0.94 Ω is obtained for ALC‐6000‐800 and ACL‐32000‐800, respectively . The relaxation time τ 0 for ALC‐6000‐800 and ACL‐32000‐800 supercapacitors is also calculated to be as short as 0.83 s and 1.18 s, respectively, which guarantees a rapid response of both supercapacitors (Figure g) . Moreover, a close and excellent cycle performance of ALC‐6000‐800 by 93.8 % and ALC‐32000‐800 by 92.4 % capacitance retention after 10,000 cycles at a high current density of 10 A g −1 is observed (Figure h).…”

“…[2b] The relaxation time τ 0 for ALC-6000-800 and ACL-32000-800 supercapacitors is also calculated to be as short as 0.83 s and 1.18 s, respectively, which guarantees a rapid response of both supercapacitors (Figure 6g). [39] Moreover, a close and excellent cycle performance of ALC-6000-800 by 93.8 % and ALC-32000-800 by 92.4 % capacitance retention after 10,000 cycles at a high current density of 10 A g À 1 is observed (Figure 6h). As further demonstrated in the Ragone plots (Figure 7h and S10), ALC-32000-800 supercapacitor delivers a high energy density of 10.4 Wh kg À 1 at a power density of 0.25 kW kg À 1 and the energy density only drops to 5.3 Wh kg À 1 at 12.1 kW kg À 1 .…”

Conductive Silk‐Based Composites Using Biobased Carbon Materials

“…Increasing concentrations of biobased carbon lead to a significant reduction in the resistivity of the gauges (Figure g). This reduction is greater for chitin‐derived carbon than for wood‐derived carbon, which may be attributed to the doping effect of nitrogen functionalities in chitin‐derived carbon . The gauges from chitin show resistivities ranging from 62.9 Ω m (carbon content: 0.1 wt%) to 1.9 Ω m (carbon content: 20.0 wt%).…”