Figure 4 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
![(a) Microporous, (b) mesoporous, and (c) macroporous carbon materials were synthesized using zeolite, mesoporous silica, a synthetic silica opal, respectively [58].](publication/349636151/figure/fig2/AS:995847177269249@1614439877149/a-Microporous-b-mesoporous-and-c-macroporous-carbon-materials-were-synthesized.png)
(a) Microporous, (b) mesoporous, and (c) macroporous carbon materials were synthesized using zeolite, mesoporous silica, a synthetic silica opal, respectively [58].
Source publication
In this review, the efforts done by different research groups to enhance the performance of the electric double-layer capacitors (EDLCs), regarding the effect of the modification of activated carbon structures on the electrochemical properties, are summarized. Activated carbon materials with various porous textures, surface chemistry, and microstru...
Context in source publication
Context 1
... general template synthesis route goes on through three typical passages: (1) Synthesis of the composite of carbon precursor and inorganic template, (2) Carbonization of the prepared composite material, and (3) Removal of the inorganic template. Figure 4 gives an illustration of various templates used in literature for the synthesis of micro-, meso-, and macroporous carbon for supercapacitor applications. Liu Wan et al. [59] synthesized highly mesoporous texture using a soft-templating agent (surfactant-F127). ...
Similar publications
Nitrogen‐doped porous carbon materials with planar holes not only inherit the structure advantages of porous carbon materials, but also have a unique planar porosity and heteroatomic doping feature, showing enormous interest in the field of energy storage and conversion. Nevertheless, rational and controllable design of honeycomb‐like porous carbon...
Citations
... In the case of conductive polymers, they usually use toxic monomers in the synthesis process, and the poor cyclic stability caused by a large volume change is also a problem in charge-discharge process of supercapacitors based on conductive polymers [9]. Therefore, carbon materials are more attractive supercapacitor electrodes due to its non-toxic, sustainability, high conductivity, and good chemical stability [10,11]. ...
Lignin has gained extensive attention as an ideal carbon precursor due to its abundance and high carbon content. However, the agglomeration of lignin and additional corrosive and unrecyclable reagents in direct pyrolysis still limit the development of lignin-based porous carbons. Herein, a facile and eco-friendly strategy was proposed to fabricate hierarchical porous lignin/cellulose-based carbon materials (LCs). In the process, cellulose nanofibrils acted as the skeleton of the bio-aerogels, which supported lignin and benefit the preparation of the LCs. Moreover, the specific surface area and the graphitization degree of LCs can be regulated by varying the cellulose content. Without activation, the bio-based carbon material (LC30) had a high specific surface area of 1770 m² g⁻¹, which displayed high specific capacitance of 216.2 F g⁻¹ at the current density of 0.5 A g⁻¹. The supercapacitor based on LC30 also showed outstanding energy density of 12.3 Wh kg⁻¹ at the power density of 50 W kg⁻¹. The sustainable raw material, simple and harmless preparation process, and remarkable electrochemical performance enable LC30, a promising supercapacitor electrode for energy storage.
... Typically, to improve the capacitive process, increasing the surface area will be a recommendation [24]. On the other hand, if improving the diffusioncontrolled process is of interest, doping the material with a suitable heteroatom or metal compound is a promising approach [25]. However, the aforementioned misunderstanding could lead to the poor selection of approaches to further improve the system's capacitance. ...
... EDLC의 전기화학적 성능을 향상시키기 위해서는 탄소 물질의 비표면적, 기공크기 및 전기전도성이 중요 한 영향을 줄 수 있기에, 탄소의 형태를 변경하고 기공 을 조절하는 등 다양한 연구가 진행되고 있다 (4,5) . 또한, 바이오매스 폐기물에 의한 환경 오염 문제를 해결하기 위해 바이오매스 폐기물에서 효과적으로 탄소 물질을 제조하는 방법도 연구되고 있다 (6) . ...
An oxygen (O 2) atmospheric plasma treatment is employed to carbon precursor to enhance the hydrophilicity and wettability. The plasma-treated carbon is then applied as active materials for supercapacitor electrode to enhance the specific capacitance. First, tobacco leaves are separated from heated tobacco waste, followed by washing and drying process. The subsequent carbonization under nitrogen atmosphere is performed to obtain carbonized tobacco leaves (CTL). The O 2 plasma treatment is employed on as-synthesized CTL to provide hydrophilic functional groups which enhances the wettability. In a three-electrode system, CTL treated with a plasma power of 120W for 30 s exhibits 1.5-fold higher specific capacitance compared to CTL without a treatment of plasma, owing to the improved adhesive property with the electrode. As a result, a O 2 plasma treatment have increased the specific capacitance of CTL, suggesting the facile method to enhance the electrochemical performance of carbonized materials synthesized from biomass wastes.
... Supercapacitors have received a lot of attention as energy storage devices, owing to its high power density, long cycle life, almost maintenance free and environment friendly nature [1][2][3][4]. They have been widely applied in electric vehicles for start-up and regenerative braking [5][6][7][8]. ...
... To enhance the specific capacitance, CNFs were activated in a few studies; however, activation did not lead to significant improvements in capacitance as activation improves the micropore volume, which cannot be accessed by electrolyte. 2,3 Further tuning the mesopore and micropore volumes using activation is not a standard practice for carbon nanofibers, unlike activated carbon. Hence, porous carbon nanofibers with excellent mesopore volume were prepared using physical etching of selective polymer from polymer-polymer blends of polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP), PAN/poly methyl methacrylate (PMMA), and PAN/polyacrylic acid (PAA). ...
Carbon nanofiber-based electrodes are generally embedded with either metal oxides or two-dimensional materials to enhance their specific capacitance and rate performance. For the first time, a flexible carbon nanofiber electrode consisting of metal oxide (RuO 2 ) and two-dimensional MXene was prepared to realize the synergetic effect on the electrochemical performance. This ternary composite electrode was prepared by electrospinning RuO 2 , and MXene dispersed polyacrylonitrile precursor solution, followed by thermal treatment. The distribution of RuO 2 nanoparticles and delaminated MXene sheets within a carbon nanofiber matrix was examined using X-ray diffraction and transmission electron microscopy, while morphological analysis was carried out using scanning electron microscopy. The electrode with pseudocapacitive RuO 2 and layered MXene facilitated charge storage by faradic reactions and intercalation of electrolyte ions. Electrochemical studies demonstrated that the prepared ternary composite electrodes exhibit a specific capacitance of 322 F g ⁻¹ with a capacitance retention of 90% after 2500 cycles at 1 A g ⁻¹ . Additionally, the ternary composite showed an excellent rate capability with a minimal drop in capacitance when the current density was varied from 2 A g ⁻¹ to 10 A g ⁻¹ .
... The three-electrode configuration is useful in the investigation of the chemistry of the active electrode surface as well as the redox behavior of the active electrode material. 23 Two different aqueous electrolytes were used in the electrochemical experiments. One is 1 M H 2 SO 4 , the other is KOH solutions with two concentrations (1 and 6 M). ...
An anthracite coal-derived activated porous carbon is proposed as a promising carbon electrode material for supercapacitor (SC) applications. The specific capacitance of this activated carbon SC electrode is related to the characteristics, such as specific surface area (SSA), pore size distribution (PSD), wettability, and conductivity. In the present work, a series of anthracite-derived activated carbons (ABACs) were prepared via a multi-stage activation process and used as electrode materials for SCs. The multi-stage activation experiment was developed by exploring different activation temperatures, precusor/activating agent mass ratios, and process treating environments. The electrochemical performance of ABACs was evaluated in a three-electrode testing system. Multiple electrolytes were utilized, such as 1M sulfuric acid (H2SO4), and 1M and 6M potassium hydroxide (KOH) solutions. An optimum ABAC electrode was obtained, characterized by its largest wettability and superior conductivity, and achieved excellent electrochemical performance. The three-electrode system exhibited a specific capacitance of 288.52 F/g and 260.30 F/g at 0.5A/g
1
in the 1M sulfuric acid and 6M potassium hydroxide electrolytes, respectively. It was found that moderate multi-stage activation temperatures are beneficial for the electrolyte uptake which enhances the specific capacitance. The high content of the oxygen functional groups on the AC surface greatly improved its specific capacitance due to the increase in wettability. In the 1M H2SO4 electrolyte, the working electrode exhibited better performance than in 1M KOH since the ion diameter in the acidic electrolyte was more suitable for pore diffusion. The concentrated KOH electrolyte leads to an increase in specific capacitance due to increased ions being adsorbed by a certain number of the hydrophilic pores. Moreover, the specific capacitance of the optimum ABAC sample remained at 95.4% of the initial value after 1,000 galvanostatic charge-discharge (GCD) tests at 0.5A/g, which is superior to the performance of supercapacitor grade commercial carbon.
... This improvement in the electrode wettability could be a consequence of the oxygen atoms introduced by Co 3 O 4 that could alter the electrostatic eld at the surface of graphite felt and facilitate interaction between the electrode material and water molecules. 28,44 The electrodeposition of PANI further decreased the surface hydrophobicity, with PANI-Co 3 O 4 -GF reaching a contact angle of 97 ± 0.9. The decrease in the electrode hydrophobicity resulting from the synergistic effect of Co 3 O 4 and PANI, along with the porosity and high specic surface area achieved, promotes good contact between the electroactive biolm and anode, thus enhancing electron transfer. ...
There is a global need for sustainable and clean technologies that can actively contribute to reach the net-zero carbon goal by 2050. In this context, Soil Microbial Fuel Cell (SMFC) technology has a huge potential as an affordable and green energy harvesting source and as a carbon-neutral bioremediation strategy for the treatment of polluted lands. In this work, for the first time, cobalt oxide (Co3O4) modified graphite felt (GF) electrodes are explored as the anode material in SMFCs, with the aim of promoting the development of a high-performing electroactive biofilm and, therefore, boosting electrogenesis. First, cobalt hydoxide salt are hydrothermally distributed onto the graphite felt electrodes, then Co3O4 nanoflowers are obtained by calcination. The resulting Co3O4–GF electrodes show lower hydrophobicity and higher conductivity than GF, however, when Co3O4–GF is tested as the anode of a membrane-less, air-cathode SMFC device, after an initial boost in power performance, the activity decays with time, probably due to Co3O4 leaching. To overcome this issue, Co3O4 –GF electrodes are interweaved with polyaniline (PANI), resulting in PANI–Co3O4–GF, for a much more stable SMFC system, which generates a peak power density of 70 mW m⁻² at a current density of 143 mA m⁻². This value of power density is nearly three times greater than the power generated by the same SMFC system with a plain GF anode. The interweaving of PANI onto the Co3O4–GF electrode leads to a porous structure that, while providing stability to the electrode over prolonged periods of operation, also favours microbial attachment. Overall, these results provide exciting perspectives on the development of composite carbon-based anode materials for high performing soil microbial fuel cells, thus inspiring future trends in the field.
... The textural properties of the activated carbons were determined and the N2 adsorptiondesorption data are shown in Fig. 3a and b. The adsorption-desorption isotherm of the activated materials all displayed a Type IV isotherm (Fig. 3a) according to the IUPAC classification with a H4 hysteresis loop [53,54]. The hysteresis loop was observed between the adsorption and desorption branches and indicates the presence of mesopores. ...
... This indicates that as the impregnation ratio increased from 1 to 3 the excess KOH led to destruction of the carbon structure rather than creation of a more porous material. This is consistent with the decrease in total pore volume but minimal change in the micropore volume with variation of the KOH ratio (Table S2; Fig. 3b) [54]. ...
This study reports on the valorisation of marula nutshell waste into a valuable electrode material for supercapacitors. Marula nutshell waste, a brown hard residue from marula fruits was valorised into a nitrogen-doped activated carbon (N-ACs) by KOH treatment and using melamine as a nitrogen source. The microporous and mesoporous nature of N-ACs exhibited a high surface area of 1427 m² g⁻¹ and pore volume of 0.31 cm³ g⁻¹. Three electrode measurements were done in 6 M KOH and 2.5 M KNO3 aqueous electrolytes, to examine the materials in alkaline and neutral medium. The N-ACs exhibited a capacitance of 350 F g⁻¹ in 6 M KOH and 248 F g⁻¹ in 2.5 M KNO3 electrolyte. Due to low toxicity and wider operating voltage (∼1.8 V) of 2.5 KNO3, the material was further analysed in a symmetric device. The high surface area, the defects, and the high content of nitrogen (5.1%) revealed that the material produced an outstanding energy density of 17.2 Wh kg⁻¹ and a power density of 448.7 W kg⁻¹ in 2.5 M KNO3 electrolyte. The conversion of marula nuts waste into N-ACs thus provide a means of converting biomass waste into a useful energy storage material for supercapacitors.
... This reduced polarisation between neighbouring carbon atoms result in enhanced interactions with electrolyte ions, which ultimately improves the surface adsorption of electrolyte ions. This also reduces active materials' equivalent series resistance (ESR) when used in capacitive devices [69]. ...
Swift developments in electronic devices and future transportation/energy production directions have forced researchers to develop new and contemporary devices with higher power capacities, extended cycle lives, and superior energy densities. Supercapacitors are promising devices with excellent power densities and exceptionally long cycle lives. However, commercially available supercapacitors, which commonly use high-surface-area carbon-based electrodes and organic solutions as electrolytes, suffer from inferior energy densities due to the limited accessibility of surface area and constrained operating potential window of electrolytes. To address the issue of inferior energy densities, new high-capacity electrode materials and new/state-of-the-art electrolytes, such as ionic liquids, gel polymers, or even solid-state electrolytes, have been developed and evaluated vigorously in recent years. In this brief review, different types of supercapacitors, according to their charge storage mechanisms, have been discussed in detail. Since carbon-based active materials are the key focus of this review, synthesis parameters, such as carbonisation, activation, and functionalisation, which can impact a material’s physiochemical characteristics, ultimately affecting the performance of supercapacitors, are also discussed. Finally, the synthesis and applications of different carbon-based materials, i.e., carbon nanotubes, graphene, and activated carbon, have been reviewed, followed by conclusions and outlook.
... However, MnO2 has disadvantages such as low conductivity, poor ion diffusion constant, and poor structural stability. Therefore, a high reversible capacitance, structural stability, and fast cation diffusion at high charge/discharge rates should be improved, and deterioration volume expansion can be avoided [96,97]. ...
One of the global problems is environmental pollution by different biowaste. To solve the problem, biowaste must be recycled. Waste-free technology is also a way of saving exhaustible raw materials. Research on electrochemical energy sources is currently the most dynamically developing area of off-grid energy. Electrochemical capacitors can operate for a long time without changing performance, they have smaller dimensions, high mechanical strength, and a wide operating temperature range. These properties are effective energy-saving devices. Therefore, supercapacitors are widely used in various industries. This review discussed the methods of obtaining and the characteristics of biowaste-derived activated carbon and carbon–manganese oxide (AC-MnO2)-based supercapacitor electrodes.
