Temperature Dependent Characteristics of Activated Carbons from Walnut Shells for Improved Supercapacitor Performance

Abstract

Activated carbons (ACs) have been prepared from chemical treatment of walnut shells (WS) precursor at various temperatures (400‒800 °C) by using phosphoric acid (H3PO4) as activating agent. Influence of activation temperature on the porosity development and capacitive properties of resulting carbons was investigated. Thermal post-treatment of carbons previously activated at moderate temperature, e.g. 400 °C allowed further structural and porosity modification. Then, these carbons were investigated by scanning electron microscopy, Raman spectroscopy, energy-dispersive X-ray spectroscopy, electrochemical techniques and low temperature nitrogen adsorption exhibiting high BET specific surface area of approximately 2100 m2 g-1 and a total pore volume up to 1.3 cm3 g-1. Carbon material obtained through activation by H3PO4 at 400 °C and post-treated at 800 °C was used to make electrodes which were implemented to realize AC/AC capacitor using 1 mol L-1 Li2SO4. The electrochemical capacitor demonstrated high capacitance of 123 F g-1 per mass of one electrode, reduced cell resistance and stable capacitance for 5000 galvanostatic charge/discharge cycles at 1.0 A g-1.

Application of Carbons Produced from Rice Husk in the Process of Capacitive Deionization

“…From the obtained voltammograms illustrated in Fig. 4a, it was observed that all three types of electrode materials exhibit the nearly rectangular shape of cyclic voltammetry curves CVs, indicating a capacitive behavior that mainly arises from the charge and discharge of the EDL [20]. The highest capacitive current was observed for 2E cells based on RH-AC, while the lowest one for YP50F.…”

“…For CDI, the most promising materials for electrodes are those which have a high specific surface area, a large number of subnanometric pores, good electrical conductivity and low cost [13][14][15][16][17][18][19]. Due to these properties, nanoporous carbons have attracted the attention of researchers around the world [20][21][22].…”

Особенности Влияния Углеродных Нанотрубок И Нановолокон На Электрохимические Характеристики Композитных Электродов Для Электрохимических Конденсаторов

“…В настоящее время экономические причины и экологические проблемы привлекают значительное внимание исследователей к биомассе в качестве сырья для производства углеродных материалов. Так, в качестве прекурсора для получения активированного угля с большой площадью поверхности использовались древесина, листья, пивной осадок, рисовая шелуха и другие типы биомассы [4][5][6][7][8][9][10][11]. Активированные угли успешно получают из рисовой шелухи, карбонизированной в бескислородной атмосфере [12].…”

Modified Activated Graphene-Based Carbon Electrodes from Rice Husk for Supercapacitor Applications

“…Another kind of capacitance is pseudo-capacitance; in this case, the charge is stored via fast reversible surface redox reactions [2,4,5]. High SSA nanomaterials like porous carbon, carbon nanotubes, and graphene are applied to reach high capacitance values for EDLC [6][7][8][9][10]. Various methods to produce porous carbon from different kinds of raw materials have been reported; recent research has focused on the utilization of renewable carbon precursors.…”