Starch-Derived Hierarchical Porous Carbon with Controlled Porosity for High Performance Supercapacitors

Abstract

The development of green and clean synthetic techniques to produce carbon materials for energy storage and conversion applications has motivated researchers to use sustainable biomass. In this study, hierarchical porous carbon (HPC) with very high specific surface area and controlled porosity is synthesized by a novel and facile method, which employs an exothermic pyrolysis process of starch−magnesium nitrate raw materials with subsequent high temperature thermal treatment and acid washing. The biomass starch acts as both a reductant and carbon source, while magnesium nitrate is an oxidant and provides MgO template as pore creator. The vigorous exothermic pyrolysis of starch−magnesium nitrate mixture introduces MgO@C precursor with a highly 3D porous network containing meso-and macropores. After MgO template is removed, plenty of micro-and mesopores are further created. Experimental parameters including calcination temperature, starch−nitrate ratio, and magnesium salt species are comprehensively evaluated. The HPC shows a very large specific surface area up to about 2300 m 2 g −1 and a hierarchical porous architecture composed of interconnected micro-, meso-and macropores. As an electrode material for supercapacitors, the HPC exhibits high specific capacitance (229 F g −1 at 1 A g −1 in a 6 M KOH electrolyte), good rate capability (211 F g −1 at even 10 A g −1 ) and outstanding cycling stability (94% capacitance retention after 10 000 cycles at 2 A g −1 ). The superior electrochemical performance of the HPC stems from both high surface area and the hierarchical multiporous structure, which provides an accessible pathway for electrolyte transport. These results demonstrate a very effective and low-cost method for scalable preparation of HPC using green biomass carbon source for supercapacitors, which also has potential applications such as adsorbent for water/gas treatment.

Hierarchical Porous Carbon Derived from Sichuan Pepper for High-Performance Symmetric Supercapacitor with Decent Rate Capability and Cycling Stability

“…Due to the increasing deterioration of environment and the urgent demand for clean and renewable energy, advanced energy storage technologies have gained considerable attention [1,2,3]. Among diverse energy storage systems, electrochemical capacitor, so-called supercapacitor, is recognized as one of the most promising next-generation candidates because of its ultrahigh power density, short charge/discharge time, long cycle life, stable performance, and broad working temperature, which has found many applications in consumer electronics, backup power supply, hybrid electrical vehicle, and implantable medical devices [3,4,5]. Based on the charge storage mechanism, supercapacitors can be classified as electrical double-layer capacitors (EDLCs) and pseudocapacitors [6,7].…”

“…Especially, porous carbon derived from natural substances stands out and becomes a hotspot in the field of supercapacitor, since its renewable precursor, abundant resources and easy fabrication process make it quite suitable for large-scale production and application [11,12,13,14,15,16,17]. For instance, some effective strategies, including one-step activation, template method as well as combination of carbonization and activation, have been proposed to synthesize porous carbon by adopting wheat straws, rice bran, almond shells, pig nails, plant leaves, corn, silk and starch as raw materials [5,11,12,13,14,15,16,17]. These biomass-derived porous carbon products feature substantial micropores (˂2 nm), resulting in large specific surface area and presenting high specific capacitance.…”

Improved Ion‐Transfer Behavior and Capacitive Energy Storage Characteristics of SnO2 Nanospacer‐Incorporated Reduced Graphene Oxide Electrodes

“…In a Nyquist plot, typically, an ideal capacitor without diffusion resistance exhibits a vertical curve at the low frequency region, [36,37] so that the RGOÀ SnO 2 À NR electrode with the nearly steep profile indicates more ideal capacitive characteristic than the RGOÀ SnO 2 À NP and bare RGO electrodes, as displayed in Figure 6a. In a Nyquist plot, typically, an ideal capacitor without diffusion resistance exhibits a vertical curve at the low frequency region, [36,37] so that the RGOÀ SnO 2 À NR electrode with the nearly steep profile indicates more ideal capacitive characteristic than the RGOÀ SnO 2 À NP and bare RGO electrodes, as displayed in Figure 6a.…”

“…The reaction properties of the electrode surface were further analyzed through the electrochemical impedance spectroscopy (EIS) measurement, which is a powerful tool to investigate the frequency responsive behaviors. In a Nyquist plot, typically, an ideal capacitor without diffusion resistance exhibits a vertical curve at the low frequency region, [36,37] so that the RGOÀ SnO 2 À NR electrode with the nearly steep profile indicates more ideal capacitive characteristic than the RGOÀ SnO 2 À NP and bare RGO electrodes, as displayed in Figure 6a. Moreover, the magnified Nyquist plots of the three samples in the inset of Figure 6a clearly show the Warburg impedance indicating the transition domain with a slope of almost 45°in the medium frequency region (between the semicircle and steep linear curve), which is related to the mass transfer at the electrolyte/ electrode interface.…”

Biomass-Derived Porous Carbon-Based Nanostructures for Microwave Absorption

“…The template method is a powerful tool to synthesize biomass-derived PC with tailored pore dimension and distribution. The involved hard and soft templates are both vital to the synthesis of PC materials with regulable pore dimension and surface area [82][83][84][85]. As for template method, the technology is grounded on the self-assemble of block copolymers, surfactants, organic compounds, and so forth [86,87].…”