Synthesis of Fe/N Co-doped Porous Carbon Spheres Derived from Corncob for Supercapacitors with High Performances

Abstract

Corncob, as a sustainable biomass waste, is mainly composed of hemicellulose. Herein, on the basis of natural corncob as substrates, Fe/N co-doped porous carbon spheres were designed via a consecutive FeCl3-mediated hydrothermal reaction and mild KHCO3 activation route for supercapacitor electrode materials. Owing to the low hydrolysis temperature of hemicellulose and hydrolysis promotion of Fe3+, the corncob-derived hydrochar exhibited special carbon sphere morphology. Interestingly, the carbon sphere morphology was well-preserved upon the melamine-mediated KHCO3 activation. As a result of the short ion diffusion distance, unique packing architecture, and developed micro–mesoporous structure of the carbon spheres, optimized CCAC-Fe-M-50% manifested superior ion transfer kinetics and rate performances (87% up to 20 A g–1). Meanwhile, the electrochemical investigation of CCAC-Fe-M-50% in a three-electrode setup illustrated high capacitance (338 F g–1 at 1 A g–1). In a two-electrode setup, the CCAC-Fe-M-50%||CCAC-Fe-M-50% device revealed supreme cyclability (102.7% retention after 5000 cycles) and extremely low R ct (0.59 Ω) and R s (4.54 Ω). These superior properties were attributed to the large S BET (2305.7 m2 g–1), the multiple redox possibilities (Fe3+, Fe2+, and N functional groups), and the carbon sphere morphology with a micro–mesoporous structure, which enhanced ion physisorption, pseudocapacitance, and electrolyte/ion diffusion, respectively. Besides, the fabricated CCAC-Fe-M-50%||CCAC-Fe-M-50% device in a neutral electrolyte demonstrated a superb energy density (E D) of 18.60 Wh kg–1 at the power density (P D) of 455 W kg–1. The currently presented strategy with superior results might lead to the novel development of biomass-based ultraperformance electrode materials for supercapacitors and other high-tech applications.

Ultrastable Asymmetric Supercapacitor Device with Chemically Derived and Mechanically Activated NiCo2O4

“…For the electrode preparation, a gel was formed by taking the prepared sample, activated carbon, and PVDF in a weight percentage of 85:10:5 and mixed with the N -methyl pyrrolidine (NMP). After sonication for 30 min, the obtained slurry was pasted onto the one end of the graphite rod and held at 60 °C for 6 h. By using the following equation, the specific capacitance value of two materials from the CV curve can be studied at various scan rates, − where m represents the mass of the deposited sample and v denotes the scan rate. From the integral area of the CV curve, the current in the CV curve can be calculated, which is represented by the following equation, − where V c and V a describe the highest and lowest voltage potential limit, respectively.…”

“…In this work, for the two-electrode system, a hybrid supercapacitor device has been constructed using activated carbon as the negative electrode and the 1 h milled sample as the positive electrode. At this stage activated carbon plays a crucial role in getting excellent electrochemical performance with the advantages of high specific surface area (1000–3000 m 2 g –1 ), and high conductivity. , This porous structure and robust conductivity of activated carbon help in rapid electron–ion transportation through the electrolyte and electrode. Hence, high specific capacitance can be achieved by the device.…”

Repurposing N-Doped Grape Marc for the Fabrication of Supercapacitors with Theoretical and Machine Learning Models

“…In particular, using biomass waste to produce carbon materials for energy storage can yield value-added products and address challenging waste disposal problems [ 10 ]. Various studies in the literature have shown the exemplary designs and competitive electrochemical performances of biomass-based low-cost carbons compared with conventional AC [ 11 , 12 , 13 ]. Various biomass resources—such as sugarcane [ 10 ], rice husk [ 14 ], fishbone [ 15 ], garlic skin [ 16 ], wheat straw [ 17 ], etc.—have been employed to prepare AC electrodes.…”

Preparation of N/O co-doped porous carbon by a one-step activation method for supercapacitor electrode materials

“…Nitrogen doping is one of the most prevalent modification tactics for boosting electrochemical performance. Nitrogen-doping strategies include introducing extra nitrogen from ammonia, 9 urea, 10 melamine 11 etc. , or using nitrogen-rich substances (poly-aniline 12 , polyacrylonitrile 13 , gelatin 14 etc. )…”