Biomass‐based Hierarchical Porous Carbon for Supercapacitors: Effect of Aqueous and Organic Electrolytes on the Electrochemical Performance

Chi²,

et al. 2020

Adv Elect Materials

conductivity, abundant morphology, large surface area, and tunable surface properties, porous carbons have been widely used as electrode materials for supercapacitors. [6-9] Various porous carbons have been fabricated from the green precursor of biomass, which exhibits outstanding performance in supercapacitors. Theoretically, the specific capacitance of a supercapacitor depends on the specific surface area of the carbonaceous electrode materials. The larger the surface area, the more the charge accumulated on the interface between the electrode and electrolyte distributions. [2,10,11] Up to now, massive works have been performed to activate the electrode materials to obtain a higher specific surface area. Unfortunately, most of them used some strong corrosive etchants, such as KOH, NaOH, HNO 3 , and H 3 BO 3. [12-25] Recently, Zinc chloride (ZnCl 2) has been widely used to activate the carbon materials to prepare electrode materials with larger specific surface area and proper pore size distribution for high-performance supercapacitors. [24,26-30] It can give higher carbon yield through a dehydrating process allowing more carbon to remain in the structure. [26,27] However, these traditional activation methods can improve the specific surface area of carbon materials at the cost of graphitization. [31] It is known that the electrical conductivity is vital to the electrochemical performance, especially for the rate capability in supercapacitors, which can be improved by increasing the graphitization degree of carbons. [32,33] Cobalt (Co) catalytic graphitization is an effective method to improve the graphitization of carbon materials. Jiang et al. used cobalt nitrate as the graphitization catalyst to synthesize partially graphitized ginkgo-based activated carbons showing a high performance of 178 F g −1 at a scan rate of 500 mV s −1. [32] Chang et al. reported a method of Co 2+ catalyzed graphitization and KOH activation, by which an interconnected nitrogen-doped hierarchical porous carbon with small mesopore size (2-4 nm) and high microporosity (86.8%) was synthesized from the biomass of Firmiana simplex fluff and exhibited an ultrahigh capacitance in supercapacitors. [34] It shows great advantages over the high-temperature treatment with high energy consumption and the related reduction of the surface area. Biomass is a kind of naturally abundant and costeffective precursors to prepare porous carbon materials for The high specific surface area and the fine electrical conductivity are the vital impacts, but they are always a pair of mutually counterbalancing factors in carbon-based supercapacitors. Herein, a facile strategy of the combined CoCl 2 catalytic graphitization and ZnCl 2 activation is applied to synthesize porous carbonaceous materials with enriched nitrogen and oxygen doping from a cheap and abundant biowaste of peanut shells. The as-produced carbon materials possess high surface area (1745-2257 m 2 g −1), naturally nitrogen/ oxygen co-doping, and hierarchical porous structure. These physicochemical p...

Section: Resultsmentioning

confidence: 99%

Nitrogen/Oxygen Enriched Hierarchical Porous Carbons Derived from Waste Peanut Shells Boosting Performance of Supercapacitors

Chi²,

et al. 2020

Adv Elect Materials

“…So, in order to achieve a high energy density, expanding the potential window of the used electrolyte is the first choice that should be considered. In contrast to the narrow operating voltage of aqueous electrolytes, the organic electrolyte of 1 M [BMIm]BF 4 /AN can be operated at a wide potential window of 3 V on account of its unique properties 64 – 66 . And it was used to achieve possible higher energy and power densities of NHPC-5 based supercapacitors.…”

Section: Resultsmentioning

confidence: 99%

Eucalyptus derived heteroatom-doped hierarchical porous carbons as electrode materials in supercapacitors

Chi²,

Wenelska

et al. 2020

Sci Rep

Carbon-based supercapacitors have aroused ever-increasing attention in the energy storage field due to high conductivity, chemical stability, and large surface area of the investigated carbon active materials. Herein, eucalyptus-derived nitrogen/oxygen doped hierarchical porous carbons (NHPCs) are prepared by the synergistic action of the ZnCl 2 activation and the NH 4 Cl blowing. They feature superiorities such as high specific surface area, rational porosity, and sufficient N/O doping. These excellent physicochemical characteristics endow them excellent electrochemical performances in supercapacitors: 359 F g −1 at 0.5 A g −1 in a three-electrode system and 234 F g −1 at 0.5 A g −1 in a two-electrode system, and a high energy density of 48 Wh kg −1 at a power density of 750 W kg −1 accompanied by high durability of 92% capacitance retention through 10,000 cycles test at a high current density of 10 A g −1 in an organic electrolyte. This low-cost and facile strategy provides a novel route to transform biomass into high value-added electrode materials in energy storage fields.

“…Electrolytes are another key component of carbon-based EDLCs, which also have a great effect on the electrochemical performance of capacitors, especially in practical applications. 20,21 Consequently, the adopted electrolytes and carbon electrode materials mainly determine the overall electrochemical performance of capacitors. In order to provide a valuable reference for meeting the different demands of carbonbased EDLCs in practical applications, it is essential to establish the relationship between the structure of graphitized hierarchical porous carbons and their capacitive performance in different electrolytes.…”

Section: Introductionmentioning

confidence: 99%

A sustainable one-step strategy for highly graphitized capacitive carbons with hierarchical micro–meso–macro porosity

Chang

Liu

et al. 2022

Nanoscale Adv.