Molecular level one-step activation of agar to activated carbon for high performance supercapacitors

Abstract

Activated carbon was synthesized by a simple one-step calcination of deoxygenated agar in a hot KOH aqueous solution, in which KOH plays both deoxidant and activation agent. The deoxygenation course omits high temperature carbonization in the conventional technology and leads to molecular level activation of agar in subsequent one-step calcination. The one-step activated carbon has superior specific surface area of 1672 m 2 g −1 and total pore volume of 0.81 cm 3 g −1 . It also shows a maximum specific capacitance of 226 F g −1 in the KOH electrolyte, which is 1.4 times as high as that for the activated carbon by the conventional two-step method. This study provides potentially economical and effective means for the production of commercial activated carbon with high porosity for supercapacitors.

High‐performance activated carbons for electrochemical double layer capacitors: Effects of morphology and porous structures

“…The HTS products, which possessed oxygen‐functional groups, underwent intense reaction with KOH at a temperature higher than 500°C, resulting in the complete destroy and restructuring of the original carbon framework and the formation of different morphologies of the resultant ACs, as shown in Figure . The de‐oxygenation of the organic components in the carbon particles during the carbonization at ~500°C likely helped the ACs of HCAC‐x‐a maintain the skeletal structure in the carbon‐based spheres, which limited the structural destruction during the subsequent KOH activation …”

“…The deoxygenation of the organic components in the carbon particles during the carbonization at~500 C likely helped the ACs of HCAC-x-a maintain the skeletal structure in the carbon-based spheres, which limited the structural destruction during the subsequent KOH activation. 49 Figure 2D-F illustrates the distributions of the sizes of the AC spheres of HCAC-x-5 (x = 40, 20, and 10), which were calculated from the SEM images. The average sizes of the ACs of HCAC-x-5 are 3.14 ± 1.07 μm, 6.55 ± 1.03 μm, and 11.30 ± 1.71 μm, which are almost the same as 3.41 ± 0.70 μm, 6.72 ± 1.35 μm, and 11.45 ± 1.60 μm of their corresponding precursors, for the ACS of HCAC-10-5, HCAC-20-5, and HCAC-40-5, respectively.…”

Nitrogen‐Immobilized, Ionic Liquid‐Derived, Nitrogen‐Doped, Activated Carbon for Supercapacitors

“…Supercapacitors are being considered as promising energy storage devices because of their high power density, high reversibility, and long cycle life. The large surface area and high electronic conductivity of electrode materials are in demand because the capacitances of supercapacitors depend on the electrochemical double layer (EDL) formed by the interaction between the surface of the electrode materials and the electrolyte . Porous carbon materials are most commonly used as electrode materials for supercapacitors because they are economically, ecologically, and technologically acceptable according to modern green chemistry principles .…”

All-carbon positive electrodes for stable aluminium batteries

“…Dai and coworkers reported the electrochemical performance of Al/graphite rechargeable batteries at low temperature and the discharge capacity was superior than that at room temperature. According to the state-of-the-art, graphitic materials that hold high reversible ion intercalation/de-intercalation ability appear to be the most promising active positive electrode materials [23][24][25][26][27][28][29] . In the exploration of low-cost electrolytes, low-temperature melt salts were found to possess the ability to enable the active anions for fast transport in the electrolytes [10,11,30,31] .…”