Carbon Materials For High-performance Supercapacitors Research Articles

Activated Carbon Derived from Waste Oil Shale Semi-Coke for Supercapacitor Application.

As fossil fuels gradually deplete, oil shale, one of the world's largest energy resources, has attracted much attention. Oil shale semi-coke (OSS) is the main byproduct of oil shale pyrolysis, which is produced in large quantities and causes severe environmental pollution. Therefore, there is an urgent need to explore a method suitable for the sustainable and effective utilization of OSS. In this study, OSS was used to prepare activated carbon by microwave-assisted separation and chemical activation, which was then applied in the field of supercapacitors. Raman, XRD, FT-IR, TEM, and nitrogen adsorption-desorption were adopted to characterize activated carbon. The results showed that ACF activated with FeCl3-ZnCl2/carbon as a precursor has larger specific surface area, suitable pore size, and higher degree of graphitization compared with the materials prepared by other activation methods. The electrochemical properties of several active carbon materials were also evaluated by CV, GCD, and EIS measurements. The specific surface area of ACF is 1478 m2 g-1, when the current density is 1 A g-1, the specific capacitance is 185.0 F g-1. After 5000 cycles of testing, the capacitance retention rate was as high as 99.5%, which is expected to provide a new strategy of converting waste products to low-cost activated carbon materials for high-performance supercapacitors.

Scalable Preparation of Nanostructured Hybrids of Transition Metal Sulfide/Oxide With Carbon Materials for High-Performance Supercapacitors

The ever-growing demands and rapid development of energy storage devices and systems pressed the need for low-cost yet highly performing electrode materials. The transition metal oxide and sulfide-based hybrids holds great promise as the active electrode materials in supercapacitors, due to their large surface area and variable oxidation states. These properties enable significantly high energy storage via electrical double layer and pseudocapacitive charge storage mechanisms. Herein, we discuss a facile, scalable, and environment-friendly preparation process to produce transition metal sulfide and oxides based on resource rich metals such as Mn, Fe, V etc. and their hybrids with carbonaceous materials, such as carbon nanotubes and graphene. This strategy encompasses solvent-less mixing of a metal salt, surfeit yet non-toxic abundant elemental sulfur and carbon precursor under continuous ball milling and thermo-annealing. The resulting nanohybrids were thoroughly investigated by means of several techniques. XRD, HRTEM, SEM, Raman and BET could gather insights on the morphology and the fine material structure, as well as on the spectroscopic properties. Finally, the electrochemical properties as supercapacitor components were investigated in regards with varyingly increasing carbon content. The nanohybrids were tested in both aqueous and organic electrolytes for bettering energy and power performances. Charge storage performances and components stability in both symmetric and asymmetric devices were assessed via CV, GCD, EIS.

Bio-Based Carbon Materials for High-Performance Supercapacitors.

Lignin, one of the components of natural plant biomass, is a rich source of carbon and has excellent potential as a valuable, sustainable source of carbon material. Low-cost lignosulfonate (LS) doped with polyaniline (PANI) has been used as a precursor to produce porous carbon. LS has a highly dispersed and sparse microstructure and can be accidentally doped with S atoms. N and S double-doped carbon can be directly synthesized with abundant mesopores and high surface area in a lamellar network using PANI as another doping source. This study explored the optimal conditions of LS/PANI material with different amounts of lignosulfonate and different carbonization temperatures. When the amount of lignosulfonate was 4 g and the carbonization temperature was 700 °C, graded porous carbon was obtained, and the electrochemical performance was the best. At 0.5 A/g, the specific capacitance reached 333.50 F/g (three-electrode system) and 242.20 F/g (two-electrode system). After 5000 charge/discharge cycles at 5 A/g, the material maintained good cycling stability and achieved a capacitance retention rate of 95.14% (three-electrode system) and 97.04% (two-electrode system). The energy and power densities of the SNC700 samples were 8.33 Wh/kg and 62.5 W/kg at 0.25 A/g, respectively, values that meet the requirements of today’s commercially available supercapacitor electrode materials, further demonstrating their good practicality. This paper provides an efficient double-doping method to prepare layered structures. Porous carbon is used for electrochemical energy storage devices.

Organic Crosslinked Polymer-Derived N/O-Doped Porous Carbons for High-Performance Supercapacitor

Supercapacitors, as a new type of green electrical energy storage device, are a potential solution to environmental problems created by economic development and the excessive use of fossil energy resources. In this work, nitrogen/oxygen (N/O)-doped porous carbon materials for high-performance supercapacitors are fabricated by calcining and activating an organic crosslinked polymer prepared using polyethylene glycol, hydroxypropyl methylcellulose, and 4,4-diphenylmethane diisocyanate. The porous carbon exhibits a large specific surface area (1589 m2·g−1) and high electrochemical performance, thanks to the network structure and rich N/O content in the organic crosslinked polymer. The optimized porous carbon material (COCLP-4.5), obtained by adjusting the raw material ratio of the organic crosslinked polymer, exhibits a high specific capacitance (522 F·g−1 at 0.5 A·g−1), good rate capability (319 F·g−1 at 20 A·g−1), and outstanding stability (83% retention after 5000 cycles) in a three-electrode system. Furthermore, an energy density of 18.04 Wh·kg−1 is obtained at a power density of 200.0 W·kg−1 in a two-electrode system. This study demonstrates that organic crosslinked polymer-derived porous carbon electrode materials have good energy storage potential.

Exhaust gas based nanoarchitectonics for porous carbon materials for high-performance supercapacitor

Pyrolyzing carbon precursors will also lead to a large amount of exhaust gas, which is a waste of resources and a huge pollution. Therefore, realizing the full utilization of exhaust gas from carbon precursors is significant. Herein, cobalt (Co) modified hard templates with micropores or mesopores is used to prepare porous carbon for supercapacitors, in which Co species provide the active sites for the capture and deposition of exhaust gas derived from zeoliticimidazolate framework. Using N2 as protective and carrier gas, the whole process can be realized in a simple tubular furnace. The obtained PC can replicate the morphology and pore structure of the hard template with the characteristics of micropores or mesopores respectively. The microporous structure of PC gives it higher surface area and pore volume than PC with mesopores, which makes it have high capacitance of 445.7 F g−1 in supercapacitor.

A green route to synthesize nitrogen-enriched graphene-like carbon nanosheets from bio-oil for supercapacitors

Two-dimensional carbon materials with the combined characteristics of high surface area, plentiful exposed active sites as well as short ion transport distance, have received great attention for fast charge storage. Herein, an environmentally-friendly method is proposed for the fabrication of nitrogen-enriched graphene-like carbon nanosheet (NCS) from bio-oil by using graphitic carbon nitride (g-C3N4) as a self-sacrificing template and nitrogen source. Notably, compared with our previous work, the obtained carbon material possesses higher nitrogen content (8.09 at.%). Meanwhile, the carbon nanosheets have a much thinner thickness (~2.8 nm), large size and high electrical conductivity (85 S m−1). Consequently, the energy density of the symmetric supercapacitor displays high energy density of 10.6 W h kg−1 at a power density of 131.1 W kg−1 in 1 M H2SO4. This study proposes an eco-friendly and low-cost route for the preparation of graphene-like carbon materials for high-performance supercapacitors.

Biomass-Derived Carbon Materials for High-Performance Supercapacitors: Current Status and Perspective

Supercapacitors are electrochemical energy storage systems that depend on high-surface-area electrodes and can play a dominant role in areas that require high power delivery or uptake. And of various electrodes, biomass-derived carbonaceous electrodes have recently shown impressive promise in high-performance supercapacitors because of their widespread availability, renewable nature and low-cost electricity storage. Based on this, this review will discuss the current status of biomass-derived carbon materials in supercapacitors and highlight current research with a specific emphasis on the influences of structure and elemental doping on the electrochemical performance of corresponding carbon electrodes. This review will also discuss the gap between laboratory achievements and practical utilization in terms of these biomass-derived carbon materials and outline practical strategies for future improvement.

Porous N self-doped carbon materials for high-performance supercapacitors via nanosized silica template combined with pyrolysis method

Advanced carbon with tunable priority and composition have been considered as the promising component for electrode materials of high-performance supercapacitor. Herein, the nitrogen self-doped porous carbon materials (NPCM) are fabricated via a one-step pyrolysis using 4,4′-bis (3,4-dicyanophenoxy) biphenyl (BPh) and nanosized silica as the precursor and sacrificial template, respectively. It was found that the obtained NPCM showed moderate specific surface area (550.5 m2 g−1) with nitrogen content of 2.1 at.%. Meanwhile, the electrode material based on the prepared NPCM exhibited great specific capacitance of 248 F g−1 at current density of 1 A g−1. The great capacitive performance is mainly due to the interaction of the following two factors: (i) the appropriate pore structure that facilitates the ion adsorption and transportation; (ii) the C–O, C=O, and N-6 functional groups derived from heteroatom doping, which contribute to increase pseudocapacitance active sites. Thanks to its tunable porosity and electrochemical properties, the novel NPCM electrode materials can have a promising prospect in the application to high-performance supercapacitors.

N, O self-doped hierarchical porous carbon materials for high-performance super-capacitors

Biomass carbon materials have been widely used as electrode materials for super-capacitors (SC) due to their economic, environmental, and sustainable characteristics. In this work, we proposed that the Sapindus Mukorossi Peel (SMP) was used as a precursor to prepare a Sapindus Mukorossi Peel-based activated carbon material (SMPC) through carbonization and KOH activation. The morphology and structure of SMPC were characterized by various test methods. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to characterize its electrochemical performance. The results show that SMPC has suitable pore size distribution, a large number of heteroatom functional groups and excellent electrical conductivity. In addition, the amount of activator also has an important influence on the performance of SMPC. When the mass ratio of carbon material to KOH is 1:3, the prepared sample SMPC-3 has the largest specific surface area (SSA) was 1254.5 m2/g. Moreover, SMPC-3 also has excellent electrochemical properties, high specific capacitance (at 1 A/g, the specific capacitance can reach 314.5F/g), good cycle stability (at 5 A/g, cyclic charge and discharge 5000 times, the specific capacitance is only lost by 4.2%.), superior rate performance (when the current density is increased from 0.5 A/g to 10 A/g, the specific capacitance retention rate is 80.4%). Assembling SMPC-3 // SMPC-3 into a symmetrical SC shows higher energy density (at 0.1 A/g, the energy density is 6.68 Wh/Kg) and power density (at 5 A/g, the power density is 3250 W/Kg).

Pore-structure regulation of biomass-derived carbon materials for an enhanced supercapacitor performance.

Herein, we report a dual-porogen synthesis strategy to fabricate a micro-/meso-/macroporous carbon material for supercapacitors from biomass. The hierarchically porous carbon material was produced in a facile way by pyrolyzing C10H14N2Na2O8/KOH (dual-porogen) and walnut peel (biomass carbon source) along with HCl solution etching. Such an admirable dual-porogen strategy opened up the closed pores and broadened the range of pore distribution for the carbon material from 0.55-1.76 nm to 0.59-2.53 nm as the mass ratio of walnut peel and C10H14N2Na2O8 increased from 1 : 0 to 1 : 2, making up for the shortcomings of the narrow microporous distribution caused by the use of potassium hydroxide exclusively. As expected, the hierarchically porous carbon materials with a regulated structure with an appropriate pore volume, broadened pore-size distribution, ultrahigh specific surface area, as well as the effective hetratom dopping manifested its remarkable capacitor performances. The highest specific capacitance for a porous carbon material achieved was 557.9 F g-1 (at 1 A g-1) and 291.0 F g-1 (at 30 A g-1). The highest power density could reach up to 5679.62 W kg-1, and energy density achieved was 12.44 W h kg-1, thus greatly promoting its use in the design and synthesis of high-performance electrode materials for supercapacitors.

Heteroatom-doped porous carbons derived from lotus pollen for supercapacitors: Comparison of three activators

Facile preparation of carbon-based electrode materials with high specific surface area and controllable pore structure through a green and mild strategy is highly desirable for high-performance supercapacitors. Here, hierarchically porous carbon materials were prepared by three types of metal chlorides, including ZnCl2, FeCl3, and CuCl2. Compared with porous carbons obtained by traditional ZnCl2 or FeCl3 activation, hierarchically porous carbon obtained by a facile CuCl2 activation possessed higher yield, larger specific surface area, more developed hierarchical pore structure, and higher heteroatom contents. Benefiting from the synergy of unique morphology, hierarchical pore architecture with abundant micro-/mesopores and coexistence of numerous redox-active nitrogen and sulfur funtionalities, the as-prepared hierarchically porous carbon activated by CuCl2 exhibited superior electrochemical performance in aqueous electrolyte, including a large specific capacitance of 389.3 F g−1 at a current density of 1 A g−1, excellent rate capability and good cycling stability in a three-electrode system. Moreover, the assembled carbon-based symmetric supercapacitor based on CuCl2-activated carbon electrode delivered a significantly increased energy density of 30.4 Wh kg−1 at a power density of 496.0 W kg−1 in comparison to ZnCl2 or FeCl3-activated carbon electrodes. Therefore, CuCl2 activation is proved to be an effective chemical activation agent for the synthesis of biomass-derived carbon materials for high-performance supercapacitors.

Cattail fiber-derived hierarchical porous carbon materials for high-performance supercapacitors

Biomass-derived porous carbon materials are very promising in the fields of energy storage and conversion, owing to their fascinating features, such as superior renewability, low cost and environmental friendliness. Correspondingly, developing a safe and energy effective strategy for fabricating advanced carbon from biomass has drawn tremendous attention. In the present work, cattail fiber-derived porous carbon is prepared with an impregnation-single stage calcination method by using K2CO3 as the activating agent. The dosage of K2CO3 and calcination temperature are optimized according to the supercapacitive performance of the corresponding carbon materials. The optimal CPC-2-600, which is fabricated with a mass ratio of 2:1 for K2CO3 to cattail fibers and calcined at 600 °C, possesses much larger specific surface area and more abundant micropores and mesopores than the pristine carbon fabricated without using K2CO3 (denoted as CPC-0-600), leading to an improved supercapacitive behavior. As the electrode material for the three-electrode supercapacitors, CPC-2-600 displays a specific capacitance of 273.8 F g−1 at 1.0 A g−1 in 6.0 M KOH solution, as well superior rate capability. Moreover, the CPC-2-600-based symmetrical configuration delivers an energy density of 27.44 Wh kg−1 at 400 W kg−1. Even the power density is up to 8000 W kg−1, the energy density is still maintained as high as 16.67 Wh kg−1, which is much superior to CPC-0-600. Also, the symmetrical configuration exhibits good cycling stability. This work offers a hierarchical porous carbon from cattail fibers for high-performance supercapacitors. Moreover, the mild, effective and low-cost fabrication strategy is also suitable for preparing other biomass-based carbon, which is promising in heterogeneous catalysis, energy storage and conversion devices, and so on.

Hierarchically Porous N, P-Codoped Carbon Materials for High-Performance Supercapacitors

Carbon materials with heteroatom doping have drawn enormous attention as electrode materials owing to their tunable surface properties and adjustable structures, yet their facile obtainment has bee...

Biomass Straw Based Activated Porous Carbon Materials for High-Performance Supercapacitors

Biomass straws are often regarding as agricultural waste, usually burned off in rural areas, which results in severe resource waste and air pollution. In this work, biomass-based porous carbon material with a lamellar microstructure is obtained via simple hydrothermal and subsequent KOH activation, the optimum activate process is determined by the proportion of activator. Scanning electron microscopy (SEM) and nitrogen adsorption techniques are conducted to investigate the physical properties of the materials. Cyclic voltammetry and constant current discharge/charge in the three-electrode system and symmetrical double-layer capacitors results indicate the best electrochemical performance of SCA-1.5 electrode material, with a capacity of 250.0 F g-1 at 1.0 A g-1. And notably, high recycling stability at a high cycling rate of 1.0 A g-1 after 18,000 cycles.

B/N-Codoped Carbon Nanosheets Derived from the Self-Assembly of Chitosan-Amino Acid Gels for Greatly Improved Supercapacitor Performances.

This work presents an efficient strategy for preparing chitosan (CS)-derived boron (B), nitrogen (N)-codoped porous carbon (C) nanosheets by using three amino acids with different acidities and the help of boric acid. Amino acids act not only as a N sources but also as the structure-directing agents through the interaction with CS to induce the formation of special morphology and structure. Boric acid serves both as the B source and as the reactive template, improving activition efficiency to creat more pores. When amino acids with different acidities are added, the morphology of the prepared samples changes from large bulks to thin nanosheets. In particular, the as-prepared carbon formed by a CS-aspartic acid gel precursor shows thin curved nanosheets. After adding KOH and boric acid, the samples possess loose and cross-linked morphologies with porous structure, which is favorable for ion transport and has benefit for the supercapacitor (SC) performance. As a result, the obtained B/N-codoped porous carbons show enhanced electrochemical performance. The sample CS/His-B prepared with basic amino acid shows the superior capacitance of 478 F g-1. Meanwhile, the assembled symmetric SC achieves a maximum energy density of 30.1 Wh kg-1 when the power density is 225.1 W kg-1 and demonstrates an ultralong cycling life for which the retention of capacitance is approximately 100% after 100 000 cycles. The maximum area capacitance is up to 12.7 F cm-1 with 50 mg of active material loaded. For an all-solid-state SC using KOH-polyvinyl alchydroohol (PVA) electrolyte, the device owns a wide potential range of 1.4 V, which shows an excellent maximum energy density of 14.4 Wh kg-1 and still remains 4.4 Wh kg-1 at the power density of 1049.5 W kg-1. B/N-codoped carbon nanosheets derived from the self-assembly of chitosan-amino acid gels represent a promising route for preparing carbon materials for high-performance SCs.

Laser direct writing of heteroatom-doped porous carbon for high-performance micro-supercapacitors

Simultaneously improving the specific surface area, pore size distribution, heteroatom doping, and electrode/electrolyte interface of carbon materials for high-performance supercapacitors or micro-supercapacitors (MSCs) is difficult, especially in one-step laser direct writing process. This study demonstrates a general and effective strategy for the first time to prepare heteroatom-doped porous carbon structures with high specific surface area, narrow pore size distribution, heteroatom doping, and improved electrode/electrolyte interface, through one-step laser direct writing on precursor-incorporated polyimide (PI) films, which endow the MSC with dramatically improved capacitive performance. The typical MSC prepared on the PI/H3BO3 film exhibits an ultrahigh specific capacitance of 65.7 mF/cm2 at 0.05 mA/cm2, which is more than 5400% of the 1.2 mF/cm2 and 250% of the 25.5 mF/cm2 for MSCs prepared on as-prepared H3BO3-free PI film and commercial PI film, respectively. Moreover, the MSC shows excellent cycling stability (>50000 cycles), outstanding flexibility (foldable), long-term stability (>6 months), and the capability of delivering high voltage and energy by connecting in series and parallel, which make it a promising energy storage component in next-generation portable electronics. What’s more, P-doped porous carbon MSCs and fluorinated porous carbon MSCs with high capacitive performances were also demonstrated by incorporating H3PO4 or NaBF4 into PI films followed by the same laser direct writing process, suggesting the generality of this approach. The strategy proposed in this work paves a new avenue for modulating structures and components and improving electrode/electrolyte interface of carbon materials for high-performance supercapacitors.

Highly graphitized and N, O co-doped porous carbon derived from leaves of viburnum sargenti with outstanding electrochemical performance for effective supercapacitors

Constructing the porous graphitic carbon materials based on the renewable biomass-derived raw materials has raised widely attention in recent years. Herein, this work proposes a cost-effective and eco-friendly approach for fabricating the highly graphitic porous carbon (HGPC) materials using leaves of viburnum sargenti for the first time. The as-prepared carbon sample exhibits a moderate specific surface area of 762.3 m2/g, a high oxygen content of 16.75 at.%, which could contribute additional pseudocapacitance during electrochemical reaction process. And the doping of nitrogen atom (0.53 at.%) could availably improve the conductivity. Consequently, the HGPC electrode delivers an excellent specific capacitance of 612.8 F/g at 0.5 A/g and a remarkable cycling stability with 96.02% capacitance retention over 10,000 cycles. Additionally, the assembled HGPC//HGPC symmetric supercapacitor presents an ultrahigh energy density of 25.6 Wh/kg at the power density of 450 W/kg. This facile technique holds great promise to offer an effective and universal methodology for fabricating renewable biomass-derived carbon materials for high-performance supercapacitors.

One-step template carbonization-activation synthesis of nitrogen-doped hierarchical porous carbon for supercapacitors

Nitrogen-doped hierarchical porous carbon with a high-specific surface area has been successfully synthesized via a one-step template carbonization-activation of nicotinic acid. The mass ratio of Mg (OH)2 and KOH to carbon precursor plays a crucial role in controlling porosity and nitrogen content of the product. Our optimized sample shows a hierarchical porous structure with a high surface area (2608 m2 g−1), large pore volume (4.0 cm3 g−1), and reasonable incorporation of nitrogen (2.2%). In addition, the electrode made using this optimized material shows a maximum specific capacitance of 282 F g−1 at a current density of 1 A g−1 and outstanding rate performance (64% capacitance retention at 20 A g−1). An assembled symmetric capacitor using this material displays a maximum energy density of 21.5 Wh kg−1 and 95% retention over 5000 cycles at 5 A g−1 at 25 °C. Moreover, our facile, simple, and efficient method of fabrication paves the way large-scale application of these porous carbon materials for high-performance supercapacitors.

Hexagonal phase NiS octahedrons co-modified by 0D-, 1D-, and 2D carbon materials for high-performance supercapacitor

It's crucial to improve the electronic conductivity, active sites and structural stability of transition-metal sulfides for better performance. Herein, hexagonal-phase NiS octahedrons were obtained through phase transition and co-modified by multidimensional carbon, i.e. 0D carbon QDs, 1D CNTs, and 2D reduced graphene oxide (NiS@C QDs-CNTs-rGO). It delivers a significantly enhanced specific capacity of 241 mAh g−1 at a current density of 1 A g−1 and capacity of 149 mAh g−1 at 20 A g−1, superior to its counterparts with other phases NiS2@CNTs-rGO (154 mAh g−1 at 1 A g−1, 52 mAh g−1 at 20 A g−1) and Ni7S6@CNTs-rGO (167 mAh g−1 at 1 A g−1, 124 mAh g−1 at 20 A g−1). Furthermore, asymmetric supercapacitors (ASC) assembled by NiS@C QDs-CNTs-rGO and graphene hydrogel achieve a remarkable cycling stability (capacity retention of 82% after 5000 cycles). XPS results confirm that strong CS bonds exist between carbon matrix and NiS NPs, which stabilizes structural stability and thus leading to excellent long-term cycling stability. The excellent electrochemical performance could be ascribed to the improved conductivity and structural stability, the co-modified 0D, 1D, and 2D carbon structures, and strong CS bonds between active material and carbon matrix.

Polyhydroxyalkanoate-Modified Bacterium Regulates Biomass Structure and Promotes Synthesis of Carbon Materials for High-Performance Supercapacitors.

Biomass-derived carbons have been extensively explored as electrode materials in supercapacitors. However, the type of biomass selected and its specific structure affects the synthesis of the advanced biomass-derived carbon materials. A green and facile method for the synthesis of carbon material with nanoscale and microscale porous structures for supercapacitors has been developed, based on regulating the original cell structure of the bacterial strain. The cell structure is modified in situ by regulating the accumulation of polyhydroxyalkanoate under controlled cultivation conditions. The novel bacterial in situ modification and nitrogen doping endow this hierarchically derived carbon material with improved performance. This material exhibits an extremely high specific capacitance (420 F g-1 at 1 A g-1 ) and long cycling stability (97 % capacitance retention after 10 000 cycles at 5 A g-1 ) in aqueous electrolytes. More importantly, the symmetric supercapacitor delivers a superior energy density of 60.76 Wh kg-1 at 625 W kg-1 in an ionic liquid electrolyte system. Moreover, all components in the synthesis are low in cost, environmentally friendly, and biocompatible. With these unique features, the bacterial self-modification mode opens new avenues into the design and production of a wide range of hierarchical structures.