Eco-Friendly Preparation of Biomass-Derived Porous Carbon and Its Electrochemical Properties

Abstract

High-porosity activated carbon (AC) was prepared from low-cost coconut shells (CS) using KOH as an activating agent with different KOH/char mass ratios. To cut down the amount of KOH used for AC preparation, freezing pretreatment for a certain number of times was carried out on CS before carbonization, which resulted in the maximum increase in the specific surface area ( S BET ) and total pore volume of 92.8 and 44.4%, respectively, in the resultant biochar. For the sake of description, AC from CS undergoing x times of freezing pretreatment and with a KOH/char ratio of y is denoted as AC- xy . The S BET values of AC-13 and AC-24 are 193 and 166 m 2 g –1 larger than that of AC-05 (2217 m 2 g –1 ), respectively. At a current density of 0.25 A g –1 , the specific gravimetric capacitance ( C g ) values of AC-05, AC-13, and AC-24 are 386, 403, and 425 F g –1 . Moreover, a symmetric supercapacitor based on AC-24 exhibits a high energy density of 14.7 Wh kg –1 at a power density of 120 W kg –1 . The energy density retention rate of AC-24 is 71.1% with the power density increased by about 110 times, indicating excellent rate capability. Additionally, a capacitance retention rate of about 95% after 3000 cycles implies an outstanding cycle lifetime of an AC-24-based capacitor. The freezing strategy developed here provides a novel route for low-cost and eco-friendly production of AC from biomass wastes for high-performance supercapacitors.

Advances in Micro-/Mesopore Regulation Methods for Plant-Derived Carbon Materials

“…Hou et al [ 97 ] carbonized freeze-dried lotus as a carbon precursor to prepare multi-porous biochar with outstanding microporosity (76.0%). In addition, Wang et al [ 98 ] further explored the influence of the number of freezing times on the freezing treatment effect ( Figure 9 ). It is found that the freezing pretreatment for three times possessed larger specific surface area, microporosity and pore volume, namely that the increase in the number of freeze–thaw cycles was beneficial to form more pores.…”

3D hierarchical tri-doped porous carbon derived from calcium lignosulfonate for high-performance zinc ion hybrid capacitors

“…The specific surface area and pore size distribution are the most important factors affecting the capacitive properties of carbon materials. [21][22][23] Therefore, the morphology and porous structure of LHPCs are studied and shown in Fig. 2.…”

Sustainable high-efficiency removal of cationic and anionic dyes using new super adsorbent biochar: performance, isotherm, kinetic and thermodynamic evaluation

“…21,22 Biochar has numerous applications in the modern world including food packaging, feed supplementation, 23 filtration of drinking water, 24 hygiene of humans and kitchen waste, cosmetics, 25 and composting agents. It is additionally utilized as an adsorbent in functional clothes and soil enrichment, 26 and as carbon electrodes in supercapacitors for the storage of energy 27 and wastewater treatment. 28 Biochar is a carbon-rich material acquired via the thermochemical transformation of biomass under a controlled atmosphere.…”