Carbon Materials For Supercapacitors Research Articles

Effect of puffing on electrochemical properties of sorghum seed based porous carbon materials in supercapacitors

Biomass-based carbon materials are renewable, affordable and environmentally friendly, possessing great potential in electrochemical energy storage as electrode materials in supercapacitors due to their large specific surface area and self-doped heteroatoms. However, the electrochemical properties of these carbon materials may be influenced to some extent by pretreatment procedures of carbon precursors. For this research, a range of porous carbon materials based on unpuffed and puffed sorghum seeds were synthesized under various pre‑carbonization and activation temperatures. Among them, the puffed sorghum seed-based porous carbon (PH-R6A7), prepared through pre‑carbonization at 600 °C and KOH activation at 700 °C, exhibits a higher graphitization degree, increased N and O content, as well as a greater variety of nitrogen-containing groups and significant increasing graphite nitrogen compared to unpuffed sorghum seed-based porous carbon (PC-R6A7) fabricated under similar conditions. These improvements result in enhanced conductivity and wettability of electrode materials, thereby boosting their electrochemical properties. In a three-electrode setup employing a 6 M solution of KOH, PH-R6A7 demonstrates an exceptional specific capacitance of 523.84 F g−1 at 1 A g−1 compared with PC-R6A7 of 366.00 F g−1; even at a high current density of 20 A g−1 it maintains a high level of capacitance at 387.94 F g−1. When employed in a double-electrode configuration at the same current density (i.e., 1 A g−1), PH-R6A7 also achieves higher specific capacitance of 357.83 F g−1 than PC-R6A7 (286.89 F g−1), accompanied by an increased energy density of 12.35 Wh kg−1 and 8.85 Wh kg−1 at a power density of 249.97 W kg−1 and 4.98 kW kg−1, respectively. Furthermore, after undergoing 10,000 cycles at 2 A g−1, PH-R6A7 demonstrates a superior capacitance retention of 99.68 % and coulomb efficiency of 99.91 %. PH-R6A7 fabricated through the combination method of puffing pretreatment and carbonization activation merits acknowledgment as an electrode material of superior performance and notable practical importance.

The relationship between the high-frequency performance of supercapacitors and the type of doped nitrogen in the carbon electrode

Nitrogen doping has been widely used to improve the performance of carbon electrodes in supercapacitors, particularly in terms of their high-frequency response. However, the charge storage and electrolyte ion response mechanisms of different nitrogen dopants at high frequencies are still unclear. In this study, melamine foam carbons with different configurations of surface-doped N were formed by gradient carbonization, and the effects of the configurations on the high-frequency response behavior of the supercapacitors were analyzed. Using a combination of experiments and first-principle calculations, we found that pyrrolic N, characterized by a higher adsorption energy, increases the charge storage capacity of the electrode at high frequencies. On the other hand, graphitic N, with a lower adsorption energy, increases the speed of ion response. We propose the use of adsorption energy as a practical descriptor for electrode/electrolyte design in high-frequency applications, offering a more universal approach for improving the performance of N-doped carbon materials in supercapacitors

Nitrogen-sulfur co-doped ZIF-8-derived carbon materials for supercapacitors with low self-discharge

Supercapacitors (SCs) have attracted extensive attention due to the properties of high power density, long cycle life, and high rate performance. However, the high self-discharge is one giant challenge for long-term energy storage applications of SC. Herein, we prepared a high-performance SC with low self-discharge based on nitrogen-sulfur co-doped ZIF-8-derived (NS-PC) materials. The synergistic effects of high-temperature carbonization and nitrogen-sulfur (N-S) doping are systematically investigated. With a carbonization temperature of 900 °C, assisted with N-S doping, the maximum specific capacitance of the NS-PC-900//NS-PC-900 symmetrical SC is 42.7 F g−1, while the power densities range from 650 to 13,000 W kg−1 at the energy densities of 10.04–7.5 Wh kg−1. The specific capacitance remains 95.7 % even after 20,000 charge-discharge cycles. More importantly, the as-prepared NS-PC-900//NS-PC-900 SC exhibits an ultra-low self-discharge rate of solely 0.025 V h−1 within 24 h. This work provides a universal strategy to fabricate high-performance SCs with low self-discharge.

Applying machine learning to understand the properties of biomass carbon materials in supercapacitors

Carbon is a fundamental material in developing electrochemical double-layer capacitors (EDLCs), also known as supercapacitors. Many studies have proven the impact of various carbon material properties, such as surface area, pore volume, and chemical surface composition, on the specific capacitance of supercapacitors (EDLCs). However, research endeavors to comprehensively evaluate the contribution of these material properties in correlation with experimental parameters, such as electrolyte concentration, voltage window, and current density, are scarce. This study aimed to employ machine learning algorithms to comprehend the interdependence between the properties of biomass-based carbon and the aforementioned experimental parameters with the capacitance of EDLCs. Four models of the machine learning algorithms were utilized in this study, including linear regression (LR), M5-Rules, Random Tree (RT), and Multi-Layer Perceptron (MLP), to determine the most suitable algorithm for analyzing and predicting the capacitance of EDLCs. The results revealed that the MLP model exhibited the highest determination correlation coefficient (R) of 0.871 with a Mean Absolute Error (MAE) of 45.069 F/g. Besides, the study utilized a machine learning correlation attribute model and observed that the supercapacitor’s surface area and pore volume demonstrated significant correlations with the same correlation ratio of 0.4. In conclusion, these findings emphasize the importance of considering surface area and pore volume in developing and optimizing supercapacitors. Finally, this study adds knowledge in supercapacitors and provides valuable insights for designing and developing high-performance energy storage devices.

Tuning N/O-doped carbon materials for supercapacitors by direct pyrolysis of imidazolinium polymer

Using structurally adjustable polymer to develop pseudocapacitive carbon materials with rich faradaic-active functionalities in the readily accessible skeleton for supercapacitors is important and still challenging. In this paper, using the “aromatic aldehydes ammonia condensation” idea and starting from the terephthalaldehyde and ammonium, highly pseudocapacitive active porous carbon materials were fabricated by simple “one pot method” and pyrolysis. The iodine-modified imidazolinium network polymer synthesized carbon at 700 °C (INP-I-700) shows a high specific surface area (606 m2 g−1) and pore volume of 0.30 cm3 g−1. Thanks to the hierarchically microporous, mesoporous and macroporous structure and diverse pseudocapacitive active N,O species, the ammonium iodide synthesized imidazolinium polymer derived INP-I-700 porous carbon material demonstrates a high specific capacitance of 199.1 F g−1 at 1 A g−1, along with superior cycling stability for symmetric supercapacitor configure with 99 % capacity retention after 10,000 cycles in 1 M Na2SO4 aqueous electrolyte. Furthermore, an attractive energy density of 27.7 Wh/kg at power density of 496.5 W/kg in Na2SO4 electrolyte in the voltage range of 0–2.0 V for the assembled symmetric system can be reached. The outcome of this paper can provide guidance for the construction of functionalized carbon-based materials with large specific surface area.

In-situ activator-induced evolution of morphology on carbon materials for supercapacitors.

Carbonaceous materials with diverse morphologies have shown unique and excellent performance in many fields, such as catalysis, adsorption, separation and energy storage. However, regulating the structural changes of these morphologies accurately using simple approaches is a difficult process. In this study, porous carbon materials with a morphology that changed from carbon spindles to fold-carbon spheres and then to regular carbon spheres were prepared assisted by in-situ activator of KNO3 in co-assembly of resorcinol/phenol resin and 1-alkyl-3-methylimidazolium bromide. The activation of KNO3 greatly improves the hydrophily, pore volume and surface area of the inert carbon skeleton, and increases heteroatom defects for the carbon framework. As electrode materials of supercapacitors, the influence of different structures on energy storage performance was studied. The obtained fold-carbon spheres showed a higher capacitance (405 F g-1) than flake, spindle and spherical porous carbon, which is due to convenient electrolyte transmission and completely available active sites.

Translational materials research - From laboratory to product: A 1200 F cylindrical supercapacitor from petroleum coke derived activated carbon sheets

Cylindrical supercapacitors are ideal energy storage devices for electric vehicle applications because of their safety, high power, and capacitance. In this regard, synthesis and utilization of activated carbon materials in supercapacitors for commercial usage is the need of the hour. Many researchers have reported the synthesis of carbon-based materials for supercapacitor application. However, the studies and application of such materials are limited to laboratory coin-cell level testing. In this work, for the first time, we have not only synthesized activated carbon sheets with a surface area of 2394 m2/g from petroleum coke but also demonstrated the commercial applicability of petroleum coke derived activated carbon sheets by fabricating a cylindrical supercapacitor with the specifications of 2.7 V and 1200 F, and the dimension of (60 × 80 mm) (D × H). The cylindrical supercapacitor exhibited a high capacitance of 1202 F with a stored energy of 1.22 Wh and a gravimetric energy density of 5.05 Wh/Kg. Also, the indigenous cylindrical device was diffusely compared with a commercially available supercapacitor of similar size, and the fabricated supercapacitor in this work reveals a great potential in terms of promising electrochemical properties for commercial applicability. The results also demonstrate that the petroleum coke carbon-based supercapacitor developed in this work can be used as an alternative to the commercial coconut charcoal carbon-based supercapacitor due to the inexpensive petroleum coke with rich carbon content.

Preparation and Application of Graphene and Derived Carbon Materials in Supercapacitors: A Review

Graphene has recently attracted a wide range of research interests due to its rigorous two-dimensional structure and extraordinary electrical, thermal and mechanical properties. As a conductive agent, an activated carbon supercapacitor can obtain better performance. This paper summarizes the latest research progress, mainly from two aspects: (1) the preparation of an activated carbon base for a supercapacitor based on waste sugar solution and the relationship between pore structure and activation parameters, and (2) the application of the two-dimensional materials graphene and its composite materials in electric double-layer capacitors, graphene–polymer composite tantalum capacitors, graphene–transition metal oxide composite tantalum capacitors, and asymmetric super capacitors. The studies found that graphene and its composite materials have obvious advantages in improving the cycle efficiency, conversion rate, and energy density of supercapacitors, the overall energy efficiency of mechanical systems, and the chemical properties of nanoelectronics. Therefore, it is urgent to summarize these works in order to promote the next development. Graphene is expected to be effectively and environmentally quantified in the near future, and its application in supercapacitors will be further expanded and matured.

Synthesis of N/P/S Co‐Doped 3D Cross‐Linked Carbon Nanosheets by Double Activation Method for High‐Performance Supercapacitors

AbstractIt is still a challenge to prepare heteroatoms‐doped carbon materials for supercapacitors by an acid‐free and alkali‐free synthesis method. Herein, the N/P/S co‐doped carbon nanosheets (NPS‐CNs) were synthesized by an in‐situ K2CO3 and Na2S2O3 ⋅ 5H2O double activation method from pyrene as carbon source, melamine‐phytic acid supramolecular aggregate as N and P source without the presence of acid and alkali. The as‐prepared NPS‐CN featured three‐dimensional cross‐linked nanosheets with abundant pores, boosting the stability of carbon skeleton and promoting the transfer of ion and electron. The abundant micropores together with high heteroatom content (15.09 %) provided abundant active sites and defects for ion adsorption. Benefitting from these merits, the NPS‐CN electrode exhibits a high specific capacitance of 485.1 F g−1 at 0.05 A g−1 as well as good rate performance of 350.3 F g−1 at 20 A g−1 in three electrode system. Simultaneously, the specific capacitance of the NPS‐CN capacitor reached 305.0 F g−1 at 0.05 A g−1 and retained 201.2 F g−1 at 100 A g−1 in two electrode system. Importantly, NPS‐CN capacitor presented an excellent cycle stability (93.4 % of initial capacitance after 30,000 charge/discharge cycles). This work opened a less harmful route to prepare NPS‐CNs from small polycyclic aromatic hydrocarbons for energy storage devices.

Rapeseed meal-derived N,S self-codoped porous carbon materials for supercapacitors

N,S self-doped porous carbon with high specific surface area and gravimetric specific capacitance from rapeseed meal was successfully synthesized.

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.

Facile synthesis of nitrogen and oxygen co-doped hierarchical porous carbon materials for high performance super capacitors

Nitrogen and oxygen co-doped hierarchical porous carbons (NOPCs) is prepared by the pyrolysis of polyethylene glycol-200 (PEG) and triazine carbon forming agent (CFA) using MgO as template. The PEG/CFA/MgO mixtures were compacted to form a consolidate solids, which play a key role for the formation of NOPCs. The morphology, microstructure, phase structure, textural property, surface element composition and thermal stability properties of NOPCs were investigated. It was demonstrated that the NOPCs exhibit hierarchical porous structure, high specific surface area (the largest SBET of 1244 m2/g), and abundant mesopore structures without any activation. Benefiting from the unique porous structure and rich heteroatom functional group (1.34 at % N and 20.33 at % O), the NOPC-900 electrode shows a specific capacitance of up to 347 F/g at 0.5 A/g and can keep 187 F/g even at 50 A/g. Moreover, the NOPC-900 electrode shows good cycle life with capacitance retention of 90% after 10,000 cycles. This paper provides a new, convenient way to construct hierarchical porous carbon materials for super capacitors.

Bimetallic sulfide based on various carbon materials for supercapacitors

The NiCo2S4/C hybrid material was successfully prepared by a simple one-step hydrothermal method. Carbon composite increases the specific surface area of the material and provides more ion attachment points during the electrochemical process. Conducive to the ion transportation and transfer, the composition of carbon material greatly improves the conductivity of the hybrid material. Electric double-layer capacitor materials can accept transferred ions faster than pseudocapacitor materials, enable the hybrid materials better adapt to intensity current changes. Compared with a single carbon material or a pseudocapacitance material, it has a higher specific capacity. This discovery is of great significance to the research of pseudocapacitive materials and supercapacitors.

Carbon nanomaterials for supercapacitors: two electrode scheme

In this paper, the electrochemical and texture characteristics of electrode materials made of a number of promising carbon materials for supercapacitors were considered. Carbon nanofibers, thermally expanded graphite, and activated carbon derived from rice hulls were used as electrodes for supercapacitors. The paper presents a technique of synthesis of these electrode materials. A comparison of the capacitive characteristics of the electrodes using two-electrode scheme was carried out.

Biomass-derived highly porous nitrogen-doped graphene orderly supported NiMn2O4 nanocrystals as efficient electrode materials for asymmetric supercapacitors

Herein, three-dimensional N-doped porous graphene materials (3DPNG) are successfully synthesized by potassium ferrate (K2FeO4) activation and graphitization using biomass-loofah as carbon source and dicyandiamide as nitrogen source. Furthermore, the mesoporous structure and defects on the surface of 3DPNG can regulate the in-situ growth of NiMn2O4 nanocrystals formation NiMn2O4/3DPNG composite and achieve conductive networks effectively, which not only make electrolyte ions contact with internal NiMn2O4 nanoparticles, but also provide a good electron transport path for electrochemical reaction. Detailed electrochemical characterization indicate that the NiMn2O4/3DPNG electrode exhibits a specific capacitance as high as 1308.2 F g−1 at a current density of 1 A g−1, demonstrates good rate characteristics of 77.9% when current density increased to 15 A g−1. The calculation of contribution rate of pseudocapacitance demonstrate that the behavior of electrode is combining diffusion property and pseudocapacitive property. Besides, a asymmetric supercapacitor (ASC) is assembled using NiMn2O4/3DPNG as positive electrode, 3DPNG as negative electrode, which displays excellent cyclic stability (91.6% retention after 10,000 cycles) and high energy density (45.25 Wh kg−1 at the power density of 11380 W kg−1), implying the great potential application of biomass-derived carbon materials in supercapacitors.

Facile Synthesis of N,S-Codoped Hierarchically Porous Carbon with High Volumetric Pseudocapacitance

For the purpose of obtaining high-volumetric-pseudocapacitance carbon materials for supercapacitors, the nitrogen, sulfur-codoped carbon (NSC) with a unique hierarchically porous structure is synth...

Supercapacitors from Waste: Converting Pulp and Paper Mill Waste to Nitrogen Doped Supercapacitors

The conversion of waste into energy storage materials has become an important topic in the field of sustainability. The challenge being that new materials from waste should perform better than those that are currently available, be cost effective, environmental friendly and scalable. The was streams from pulp and paper mills make an ideal candidate for upgrading, as they contain a wide range of biomaterials that have the potential to be converted into carbon materials for supercapacitors. The challenge with these waste streams is that they are wet and contain a range of inorganic materials. To overcome this, hydrothermal carbonization was utilized to convert the waste streams into carbonaceous materials. Hydrothermal carbonization is a wet, low temperature, thermochemical carbonization technique that excels in converting wet biomass into carbon products that can be easily activated an converted into carbon electrodes for supercapacitors. Additionally, the carbon materials can be doped with nitrogen, phosphorus, boron and sulfur by simply adding the dopant to the raw material prior to carbonization. Doped carbon materials have displayed improved performance and stability over their non-doped counterparts, as the dopants provide additional charge storage sites, increasing capacitance. In this work we have examined the potential to upgrade black liquor, an inexpensive by product of the pulping process, via hydrothermal carbonization for supercapacitors. These materials have been doped with a range of readily available nitrogen sources (NH4Cl, melamine, urea) to increase the stability and capacitance of the electrode. Additionally, a range of activation agents (KOH, K2CO3, KHCO3 and melamine) were investigated to improve the capacitance and stability. The electrodes were tested in aqueous electrolytes, 4M KOH and 0.5M Na2SO4, with stable voltage windows of 1.1V and 1.8V, respectively. To examine the capacitance and cycle stability, cyclic voltametry and galvanostatic charge-discharge measurements were employed, finding that most materials had a capacitance <190 Fg-1 at 25 mV s-1. The electrochemical variations between the materials were further examined by Step Potential Electrochemical Spectroscopy, which allowed the decoupling of double layer and pseudocapacitance contributions. These were combined with in-depth X-ray Photoelecton Spectroscopy of the surface to draw correlations between pseudocapacitane from the carbon-oxygen/carbon-nitrogen functional groups and capacitance contributions from the double layer.

Preparation of Biomass‐Based Porous Carbons with High Specific Capacitance for Applications in Supercapacitors

AbstractSupercapacitors are developing in terms of high power and energy densities. Carbon materials can meet this challenge to a certain extent. A sustainable high‐performance carbon material for supercapacitors was prepared through the simple and green thermal pyrolysis of orange peels as raw materials by using KOH as an activator. The biomass‐derived carbon materials activated at different temperatures were evaluated as electrode materials. The adsorption properties, structure, and surface elemental chemical states of the prepared materials were studied. Carbonation temperature plays a key role in the preparation of materials, and it has different effects on the physical and electrochemical properties of materials. The opc700 and opc800 samples have large pore volumes, which provide the necessary space for the storage of electrolyte ions. The temperature has a pronounced effect on the specific surface area and the electrochemical performance. The specific surface area of opc800 is as high as 2004 m2 g−1 and the pore volume is 1.24 cm3 g−1. The maximum specific capacity of opc800 is 306.6 F g−1 at 0.5 A g−1 and the specific capacitance is 251.2 F g−1 at 20 A g−1.

Effect of Self‐Doped Heteroatoms in Biomass‐Derived Activated Carbon for Supercapacitor Applications

AbstractAs a green and effective energy storage device, supercapacitors have been attractive due to their high power density along with long cycle stability. Among various electrode materials, carbon materials have drawn significant attention due to their wonderful properties, such as high specific surface area, electronic conductivity, chemical stability and porous structures. In addition, challenges come from global warming and environmental pollution, biomass derived carbon materials feature the concepts of the sustainable development of chemistry. In this, the review not only summarizes the most advanced progress in biomass derived heteroatoms self‐doped carbon materials for supercapacitor, but also provides important guidelines for the future design of biomass‐derived carbons with heteroatoms doping in specific energy applications.

Diffusion: Revising the Concept of Pore Hierarchy for Ionic Transport in Carbon Materials for Supercapacitors (Adv. Energy Mater. 24/2018)

Diffusion: Revising the Concept of Pore Hierarchy for Ionic Transport in Carbon Materials for Supercapacitors (Adv. Energy Mater. 24/2018)