Agarose-Based Hierarchical Porous Carbons Prepared with Gas-Generating Activators and Used in High-Power Density Supercapacitors

Abstract

Due to their high surface areas and large pore volumes, porous carbons (PCs) are valuable materials for use as electrodes in energy storage and conversion devices. Biomass is an ideal precursor for the preparation of PCs in part because it is sustainable and eco-friendly. Herein, new methodology for converting agarose, a naturally occurring type of biomass that forms robust hydrogels, into PCs with tunable pore structures and high electrochemical performance is described. The synthetic process is straightforward and entails heating a gel that is composed of agarose and potassium oxalate (K 2 C 2 O 4 ). Since the salt transforms into gaseous byproducts at elevated temperatures, the decomposition process was harnessed to create activated, open pores as the hydrogel underwent carbonization. For example, a PC with a surface area of 1754.9 m 2 g −1 and a pore volume of 2.643 cm 3 g −1 was obtained by heating a mixture of agarose and K 2 C 2 O 4 in a 1:3 weight ratio at 700 °C. The material was subsequently used as the electrode material in a supercapacitor and found to display a specific capacitance of 166.0 F g −1 at 0.125 A g −1 . Varying the quantity of added K 2 C 2 O 4 resulted in predictable changes in porosity and thus offered a means to tune the textural properties and the electrochemical performance of the PCs. For example, changing the feed ratio of agarose to K 2 C 2 O 4 to 1:6 afforded a PC that exhibited a high persistent specific capacitance (64.1 F g −1 at 5 A g −1 after 10,000 cycles) and a high-power density (20 kW kg −1 at 10 A g −1 ).

Biomass-derived porous carbon materials: synthesis, designing, and applications for supercapacitors

“…13a. 155 By changing the quantity of K 2 C 2 O 4 and the temperature, the sample featured a large number of 3D, crosslinked pores in Fig. 13b and c.…”

“…Fig.13a 155. By changing the quantity of K 2 C 2 O 4 and the temperature, the sample featured a large number of 3D, crosslinked pores in Fig.13b and c. Under optimized conditions, the obtained carbon electrode exhibited a capacitance of 166 F g −1 .…”

Recent Progress in Polysaccharide-Based Materials for Energy Applications: A Review

“…The first strategy involves the carbonization of such polysaccharides in order to obtain a conductive carbon derivative. Hwang et al 51 prepared a porous carbon material using agarose-based hydrogel as a natural and nontoxic precursor. The process involved heating the gel composed of agarose and potassium oxalate (K 2 C 2 O 4 ) to carbonize it.…”

Nonstoichiometric Scandium Oxide Hybridized in N-Doped Porous Graphitic Carbon Promotes the Rate Capability of Lithium–Sulfur Batteries

“…Porous carbons that are prepared from biomass-derived materials have found utility in applications that range from CO 2 reduction through solar–thermal energy conversion to energy storage technology. − Lithium–sulfur (Li–S) batteries are highly regarded as promising next-generation energy storage devices largely because of their high theoretical energy density (2600 W h kg –1 ). In addition, elemental sulfur is abundant, inexpensive, and friendly to the environment.…”