Materials For Supercapacitors Research Articles

Aesthetic synthesis and comparative study of graphitic carbon nitride for energy storage applications

ABSTRACT Graphitic carbon nitride (gCN) has emerged as a suitable 2D material for various applications, such as photocatalysis, energy storage, and conversion. Due to their abundance of active sites, their unique layered structure, metal-free characteristics, high physicochemical stability, generous in nature, being environmentally friendly and having unique electrical characteristics. In this study, we use a one-step pyrolysis procedure to address these limitations and propose robust, low-cost, and scalable ways to synthesise materials. The synthesised gCN material graphitic phase is confirmed by X-ray diffraction analysis, the layered structure of the sp2 hybridised C-N bonding features is shown by FT-IR analysis. FESEM analyses provide insights into the morphology of gCN. Elemental identification and oxidation states were investigated using X-ray photoelectron spectroscopy (XPS). The electrochemical properties of gCN are performed using a two-electrode system with PVA/KOH electrolyte. The gCN nanostructure shows a specific capacitance of 183.20 F/g at a current density (CD) of 2 A/g, an energy density (ED) of 30.44 Wh/kg, and a power density (PD) of 2739.6 W/kg. Furthermore, the gCN nanostructure shows an excellent cycle life with 87.11% capacitance retention and 98.13% coulombic efficiency. These investigations clarify the electrochemical properties of gCN as an electrode material for supercapacitors.

Nitrogen and sulfur co-doped carbonized lignin nanotubes for supercapacitor applications

Carbon electrode material is crucial for the development of electric double-layered supercapacitor in clean energy storage and rechargeable aspects. Although lignin consists the promising biomass based carbon resource for containing higher carbon atom ratio than 60 %, it is still the difficult challenge to precisely tailoring the porous structure characteristics and surface property to facilitate the electrolyte penetration and rapid ion transportation. Herein, the lignin nanotubes (LNT) were successfully synthesized in a convenient molecular self-assembly way, which were subsequently carbonized and activated, with introduction of melamine as nitrogen doping agent, into hetero-atom doped lignin carbon nanotubes (LCNT) as electrode material for supercapacitor. The resultant LCNT exhibit excellent pore structure, and high degree of graphitization. At a current density of 0.5 A/g, the as high specific capacitance as 391.4 F/g was achieved. Furthermore, under symmetric double-layered capacitor electrode systems, the as prepared N, S co-doped LCNT electrode demonstrated a specific capacitance of 28.6 F/g at a high current density of 20 A/g, which presented a practically applicable energy storage efficiency. It has convincingly demonstrate the substantial potential of LCNT as biomass derived carbon materials for electrochemical energy storage devices, positioning them as a promising and competitive candidate for electrode materials.

Ti3C2Tx/CDs@MnO2 composite as electrode materials for supercapacitors: synthesis and electrochemical performance

Ti3C2Tx/CDs@MnO2 composite as electrode materials for supercapacitors: synthesis and electrochemical performance

Coal-Derived Porous Carbon as Versatile Electrode Materials for Aqueous, Water-in-Salt, and Organic Electrolytes, and Fabrication of Pouch Cell Supercapacitor toward Power Application

Coal-Derived Porous Carbon as Versatile Electrode Materials for Aqueous, Water-in-Salt, and Organic Electrolytes, and Fabrication of Pouch Cell Supercapacitor toward Power Application

Copper/Cobalt based metal phosphide composites as positive material for supercapacitors

The excellent conductivity and fast redox kinetics of transition metal phosphides (TMPs) have made them a suitable electrode material for energy storage in the field of supercapacitors (SCs). In this paper, coral-like Cu3P/CoP heterostructures have been obtained by a simple solid-phase grinding and subsequent phosphating method. Importantly, the Cu3P/CoP heterostructure can provide sufficient charge to further accelerate the Faraday kinetics of the redox reaction due to its ability to generate an internal electric field, thus improving its electrochemical performance. Through density-functional theory (DFT) computations, it is demonstrated that the heterostructures of Cu3P/CoP enhances the metal-like conductivity of the composite, exhibiting more electron-occupied states around the Fermi energy level and improves the charge-transfer efficiency of the heterostructure. The results show that the Cu3P/CoP-1 composite with a 1:1 Cu/Co molar ratio has the best electrochemical performance. At 1 A·g−1, it exhibits an excellent specific capacitance of 804.3 F·g−1, and when the current density is increased to 10 A·g−1, it retains its capacitance for 92.8% of 10,000 cycles. Furthermore, with a power density of 806.23 W·kg−1, an asymmetric supercapacitor (ASC) built using Cu3P/CoP-1 as the cathode may produce an energy density of 37.40 Wh·kg−1. The reasonable design of heterostructures of bimetallic TMPs in this research offers a workable plan for exploring electrode materials with excellent capacitive properties.

Solvothermally Synthesized Nickel-Doped Marigold-Like SnS2 Microflowers for High-Performance Supercapacitor Electrode Materials.

Two-dimensional transition-metal dichalcogenides (TMDs) have emerged as promising capacitive materials for supercapacitors owing to their layered structure, high specific capacity, and large surface area. Herein, Ni-doped SnS2 microflowers were successfully synthesized via a facile one-step solvothermal approach. The obtained Ni-doped SnS2 microflowers exhibited a high specific capacitances of 459.5 and 77.22 F g-1 at current densities of 2 and 10 A g-1, respectively, in NaClO4 electrolyte, which was found to be higher than that of SnS2-based electrodes in various electrolytes such as KOH, KCl, Na2SO4, NaOH, and NaNO3. Additionally, these microflowers demonstrate a good specific energy density of up to 51.69 Wh kg-1, at a power density of 3204 Wkg-1. Moreover, Ni-doped SnS2 microflowers exhibit a capacity retention of 78.4% even after 5000 cycles. Better electrochemical performance of the prepared electrode may be attributed to some important factors, including the utilization of a highly ionic conductive and less viscous NaClO4 electrolyte, incorporation of Ni as a dopant, and the marigold flower-like morphology of the Ni-doped SnS2. Thus, Ni-doped SnS2 is a promising electrode material in unconventional high-energy storage technologies.

Tailoring microstructure and conductivity of porous hollow carbon spheres to enhance their performance as electrode materials for supercapacitors

Porous carbon materials are widely used in electrical double-layered capacitors for energy storage applications due to their abundant pores, high specific surface area and excellent electrochemical stability although their intrinsic electrical conductivity is generally low. Traditional high-temperature treatment was always adopted to boost the electrical conductivity of porous carbon materials by enhancing their graphitization degree, while this would always be accompanied by severe damage to pore structure and corresponding electrochemical performance. To solve the dilemma between boosting electrical conductivity and retaining pore structure, in this research, we proposed a low-temperature catalytic graphitization for hollow carbon spheres (HCSs) prepared by modified Stöber method accompanied with a special pore structure tailoring strategy. By altering the timing of adding carbon source, followed by secondary pore-forming and catalytic graphitization, HCSs with thin and porous shell walls along with enhanced conductivity were synthesized. Compared with the untreated HCSs or high-temperature graphitized HCSs, HCSs fabricated by the aforementioned combined strategies exhibited enhanced pore volume, specific surface area (2160.1 m2·g−1, 165.3 % of the untreated group) and conductivity (16.44±0.05 S·cm−2, 221.5 % of the untreated group), demonstrating much better electrochemical performance as the mass specific capacitance reached 256.7 F·g−1 and a volume specific capacitance reached 102.7 F·cm−3 at a current density of 1 A·g−1. Moreover, due to the largely promoted conductivity, the capacitance with the catalytic graphitized HCSs as the electrode material could be further boosted up to 273.4 F·g−1 at 1 A·g−1 by exempting the generally indispensable conductive agents and a high capacitance retention of 100.7 % was achieved after 5000 cycles at a relatively high current density of 10 A·g−1. This could be attributed to local graphitization brought by dispersed catalyst particles instead of entire atom rearrangement during high-temperature graphitization which would result in severe pore vanishing. The synergy of low-temperature catalytic graphitization and secondary pore-forming might be a novel strategy in electrode material fabrication for advanced supercapacitors or other energy storage devices.

Multicomponent hierarchical Ni-MOFs/MWCNTs@Ni/Co-LDH nanohybrid as advanced electrode material for supercapacitor

Layer double hydroxide (LDH) is a metal hydroxide with two or more metal components. It has promising prospects in supercapacitors (SCs) as electrode material due to the chemical composition adjustability, excellent ion exchangeability, good redox activity and high specific capacity. However, the further application of LDH is limited to the inferior electrochemical conductivity and slow reaction kinetics. Multiwalled carbon nanotubes (MWCNTs) as electrode materials possess excellent conductivity and distinctive hollow structure but the specific capacities are low. Metal-organic frameworks (MOFs) have abundant electrochemical active sites, multifunctionality and tunable porosity, which could accelerate the process of transporting and diffusing electrolyte ions, enhancing the specific capacitance as electrode material. Hence, in this work, MWCNTs decorated with Ni-MOFs were introduced into Ni/Co-LDH to fabricate multicomponent heterostructure Ni-MOFs/MWCNTs@Ni/Co-LDH nanohybrid by in situ chemical reaction. The specific capacity of Ni-MOFs/MWCNTs@Ni/Co-LDH was 1032.0 C g−1 at a current density of 1.0 A g−1 and retained 66.0 % initial capacity following 5000 cycles at 5 A g−1. A power density of 850.0 W kg−1 and an energy density of 28.9 Wh kg−1 were obtained for the assembled asymmetric supercapacitor.

Significantly Increased Specific Discharge Capacitance at Carbon Fibers Created via Architected Ultramicropores.

Carbon is commonly used as an electrode material for supercapacitors operating on an electrical double-layer energy storage mechanism. However, the low specific capacitance limits its application. Increasing the specific surface area is by far the most common expansion method, and surprisingly, they are not always positively correlated. The overmuch specific surface will show the characteristics of nanoconfinement, and the potential synergistic enhancement mechanism of various key parameters is still controversial. In this work, carbon fiber electrodes with different ultramicropore structures were designed in order to improve the utilization rate and the discharge capacitance. It has been found that when the ultramicropore entrance's surface is too small, it will lead to the decrease of the external charge of the pore transport channel, and then, the selectivity of the opposite ions will decrease. The numerical simulation based on Poisson and Nernst-Planck equations also indicates that ions have difficulty diffusing into the micropores when their entrance surface decreases. Surface properties within the nanocontainment space become critical factors influencing ion transport and adsorption. The specific discharge capacitance of carbon fiber is increased from 3 to 1430 mF cm-2.

Al-Based MOF-Derived Amorphous/Crystalline Heterophase Cobalt Sulfides as High-Performance Supercapacitor Materials.

Transition metal sulfides (TMSs) are promising electrode materials due to their high theoretical specific capacitance, but sluggish charge transfer kinetics and an insufficient number of active sites hamper their applications in supercapacitors. In this work, a self-sacrificial template strategy was employed to construct Al-based MOF-derived metal sulfides with an amorphous/crystalline (a/c) heterophase, in which aluminum, nitrogen, and carbon species were evenly coordinated in the amorphous phase. The metal sulfides a/c-Co(Al)S-1 and a/c-Co(Al)S-2, originating from the CAU-1 and CoAl-MOF on NF as self-sacrificial templates, were investigated as electrode materials, respectively, in which the a/c-Co(Al)S-1 showed a more excellent electrochemical performance. Through acid etching CAU-1 using Co(NO3)2 followed by sulfuration, the a/c-Co(Al)S-1 with a unique 3D network structure was constructed, whose unique architecture expanded the interfacial contact with the electrolyte and provided vast active sites, accelerating the charge transportation and ion diffusion. Notably, the a/c-Co(Al)S-1 displayed a high specific charge of 1791.8 C g-1 at 1 A g-1, satisfactory cycle stability, and good rate capability. The corresponding assembled a/c-Co(Al)S-1//AC device delivered a high energy density of 77.1 Wh kg-1 at 800 W kg-1 and good durability (87.4% capacitance retention over 10 000 cycles).

Facile synthesis of samarium (Sm3+) doped cobalt-iron oxide nano ferrite as an advanced electrode material for possible supercapacitor applications

Herein, we present design and fabrication of Samarium (Sm3+) doped cobalt-iron oxide ferrites nanocomposite electrode as an efficient energy storage material for supercapacitors. We employed a simple, low cost and quick one step solution combustion method to synthesize CoFe2-xSmxO4 (x = 0.0, 0.050, 0.075 and 0.1) ferrites. The morphological and structural features of synthesized CoFe2-xSmxO4 ferrites were analysed through various analytical and spectroscopic characterization methods such as scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). These analytical techniques confirm the successful doping of Samarium (Sm3+) into cobalt-iron ferrite, and the doping does not affect the crystalline structure of pure ferrite. The electrochemical properties of the synthesized ferrites were significantly improved after Samarium (Sm3+) doping into the host cobalt-iron-oxide. The highest specific capacity about 314 F/g was achieved for CoFe2-xSmxO4 (x = 0.1) composite electrode material, in comparison to pure CoFe2-xSmxO4 (x = 0) which is about 125 F/g. However, CoFe2-xSmxO4 (x = 0.1) ferrite shows a superior capacitance retention of the order of 98 % even after 5000 cycles of operation at a scan rate of 250 mV/s. The electrode material fabricated by using CoFe2-xSmxO4 ferrite renders an energy density of 30.16 W h/kg at a power density of 400 W h/kg. The results obtained in presented studies opens new avenues for the fabrication high-performance electrode material for supercapacitor that could be well suited for light weight electronic devices, electric vehicles, and forthcoming generation supercapacitor applications.

Reliability Assessment and Multi-Physics Simulation of Additively Printed Wearable Humidity Sensor with Super Capacitive Material for Astronaut in Extreme Condition

Abstract Additive technologies, such as aerosol jet printing, direct write printing are increasingly being used in the production of printed circuit boards because they eliminate the need for costly tooling, such as photomasks or etching containers. This is because additive methods allow for the direct deposition of printing materials onto a substrate. This versatility in a broad variety of applications allows engineers to create diverse applications, such as sensing devices with ECG sensors, pulse-oxygen sensors, galvanic skin response sensors, body temperature sensors, humidity sensors, and so on. Due to its potential for adaptability and integration, the development of additively printed humidity sensors has been the subject of several prior investigations. There are still issues with the reliability of current humidity sensor technology when flexing force is coupled with the humidity sensor. For the avoidance of stability issues, it is required to develop a better printing technique, process recipe, and sensing material encapsulation. In this research, the direct-write (D-write) printing approach with a nScrypt printer was employed to print the humidity sensor as a test vehicle in a laboratory setting. The sensor was characterized by analyzing the print recipe and its interaction with humidity in regards to resistance and humidity sensitivity. Additionally, the characterization of sensor accuracy, hysteresis, linearity, and stability in relation to temperature and humidity variation has been measured. Furthermore, a multi-physics simulation model was created in order to comprehend the electrochemical processes that occur when the humidity sensor is exposed to a very humid environment.

Study on the properties of electrode materials for supercapacitors based on 1D Co-MOCPs

Three one-dimensional (1D) Co-MOCPs (23PCo–S1, 23PCo–S2, and 23PCo–S3; where 23P denotes the ligand, 2,3-pyridine dicarboxylic acid) were synthesized using a similar hydrothermal method. The molecular formulas for the isomers 23PCo–S1 and 23PCo–S2 are [Co(23P)3H2O], while that for 23PCo–S3 is [Co(23P)2H2O]. These single-crystal structures are classified into the P-1, Pca21, and P21/c space groups, displaying triclinic, orthogonal, and monoclinic symmetries, respectively. Techniques such as S-XRD, P-XRD, XPS, and SEM were applied to analyze the structures and valence states of the materials. Additionally, the electrochemical properties of the structures were evaluated using a three-electrode setup. Among these, 23P–Co–S2 demonstrated a remarkable specific capacitance of 458.5 F g−1 at a current density of 1 A g−1. In contrast, 23P–Co–S1 and 23P–Co–S2 showed specific capacitances of 192.2 and 270.6 F g−1, respectively, under the same experimental conditions.

High-performance asymmetric supercapacitor based on hierarchical hydrothermally grown CuS nanostructures

In this work, various hierarchical CuS were fabricated via an efficient one-step hydrothermal process with different surfactants (polyvinyl pyrrolidine (CS-P), Citric acid (CS-C), Oleic acid (CS-O)) and examined as electrode materials for supercapacitors. XRD, FESEM, HRTEM and BET analysis reveal the fabrication of a hexagonal crystal structure with porous microspheres of CuS-PVP having a BJH pore diameter of 16.241 nm. Among these, the CS-P electrode exhibits a superior specific capacitance of 414.28F/g at 1 A/g of current density in the KOH electrolyte. Additionally, an asymmetric supercapacitor built with CS-P as positive and Activated carbon as negative electrodes exhibited a specific energy of 27.95 Wh/kg at 624.96 W/kg of specific power at 2 A/g and demonstrated outstanding cycling stability with 80.6 % persistence of capacitance for 2500 GCD cycles at 10 A/g. Additionally, an ASC device created for use in real life and tested by charging it for 30 s managed to reach a 3-minute 50-second self-discharging duration. Hence, these favourable electrochemical findings indicate that the hydrothermally grown hierarchical CuS-PVP electrode is a bright potential material in energy storage applications.

Direct pyrolysis fabrication of N/O/S self-doping hierarchical porous carbon from Platycladus Orientali leaves for supercapacitor

To meet the growing market requirement for low-cost supercapacitor electrode materials, N/O/S self-doping hierarchical porous carbon is successfully fabricated by direct pyrolysis of platycladus orientalLeaves (POL). The obtained carbon material exhibits wide application prospects, because of simple and green-environmental technology, low-cost and satisfactory electrochemical properties, which avoided complex preparation routes and consumption of expensive chemical reagents in the traditional activation process. Under the optimum pyrolysis temperature (850 °C), the obtained POL-derived carbon (POL-850) possesses a high specific surface area (1140.2 m2g−1), sheet-like hierarchical porous microstructure, and uniform ternary heteroatoms co-doping (O: 6.79 at.%; N: 3.45 at.% and S: 2.20 at.%). As an electrode material for supercapacitor, the specific capacitance of the POL-850 reaches 224.4 Fg−1 of 0.5 Ag−1and 156.0 Fg−1 at 30 Ag−1, revealing excellent rate performance. The capacitance retention maintains 96.3 % after 10,000 consecutive charge-discharge cycles at 20 Ag−1, demonstrating superior cycling stability. Additionally, the assembled carbon-based symmetric supercapacitor device delivers a satisfied energy density of 11.0 Wh kg−1 with the power density of 65 W kg−1 and ultralong cycle-lifetime with 95.65 % capacitance retention after 10,000 charge/discharge cycles, while the Coulombic efficiency is retaining up to approximately 100 %. This work provides an easy and cost-effective way to rapidly prepare N/O/S co-doping hierarchical porous carbon for supercapacitors, which is very suitable for large-scale production.

Core-shell carbon@Ni2(CO3)(OH)2 particles as advanced cathode materials for hybrid supercapacitor: The key role of carbon for enhanced electrochemical properties

Three-dimensional porous Ni2(CO3)(OH)2 compounds were grown on carbon nanopowder using a facile hydrothermal method for the production of core-shell carbon@Ni2(CO3)(OH)2 compounds. This work successfully overcame the shortcomings related to the low electrical conductivity and poor electrical stability caused by the presence of hollows in the Ni2(CO3)(OH)2 structure. The hollow spaces were filled with carbon powder, which acted as a seed material, yielding an ideal electrode material with a large specific surface area, high electrical conductivity, and good stability. A Ni2(CO3)(OH)2 electrode containing 50 mg of carbon powder could store more energy than a Ni2(CO3)(OH)2 electrode without carbon seed materials. The Ni2(CO3)(OH)2 electrode comprising 50 mg of carbon powder has a considerably high specific capacity (181.7 mAh g−1 at 3 A g−1) and excellent cycling stability (77.9 % capacity retention after 5000 cycles), which is 1.5 times higher than that of the Ni2(CO3)(OH)2 electrode without carbon powder. Moreover, an asymmetric supercapacitor using Ni2(CO3)(OH)2 containing 50 mg of carbon powder as the positive electrode and graphene as the negative electrode exhibits a high energy density of 34.2 Wh kg−1 and a power density of 176.1 W kg−1 at a current density of 2 A g−1. Using a combination of carbon and a Ni2(CO3)(OH)2 nanowire compound to increase the electrochemical property and specific surface area, respectively, a suitable synergistic effect can be obtained, which may pave the way for efficient electrode design for high-performance supercapacitors.

Advancing electrochemical activity: Insights from Li doped Ni-MOF synthesis and performance

This study presents the first-time synthesis of a novel Li doped Ni-MOF electrode material, achieved via a one-step hydrothermal strategy. Microstructural analysis using FESEM and HRTEM revealed hierarchical hollow spherical-like nanostructures within the Li doped Ni-MOF, providing abundant active sites for ion transport and storage. This structural feature resulted in enhanced specific capacity, exhibiting battery-like behaviors. Specifically, the Li doped Ni-MOF electrode displayed a notable specific capacity of 214.2 C/g in CV curves at 0.5 mV/s and 814 C/g in GCD curves at 1 A/g. These findings underscore the potential of the Li doped Ni-MOF as a superior electrode material for supercapacitors, indicating its promising prospects for advancing next-generation high-performance energy storage devices.

Dual activated carbon derived from Keekar leaves as an excellent symmetric supercapacitor material

Porous carbonaceous materials derived from biomass, which are both cost-effective and obtained from sustainable resources, have emerged as appealing electrode materials for energy storage devices. These materials have received great interest as active electrode materials due to their ample, low-cost, sustainable nature and excellent electrochemical stability. In the present work, porous activated carbon (AC) was synthesized from Keekar leaves by dual activation using H2SO4 and KOH. This Keekar leaves derived AC (KLAC) possesses a surface area of ~1677m2g−1 with a combination of micro and mesoporosity displaying a specific capacitance of 411F/g in 6 M KOH and 219.55F/g for 1 M H2SO4 electrolytic solution at a current density of 1 A/g. Further, the symmetric devices were fabricated using both aqueous (aq.) and polymer gel electrolytes for practical evaluation of the material. The aq. and gel device are capable of delivering a specific capacitance of 108.34 F/g and 88.45 F/g, respectively, at a current density of 0.5 A/g. The aq. device offers a maximum energy density of 33.85 Whkg−1 at a power density of 562.5 Wkg−1. The outstanding capacitance retention of 89.5 % is demonstrated by the aq. device at a higher scan rate of 20 A/g after continuous 10,000 charging-discharging cycles. Such high performance and stability make KLAC a potential candidate as an affordable and sustainable electrochemical energy storage application.

Recent Progress and Perspectives on Metal–Organic Framework-Based Electrode Materials for Metal-Ion Batteries and Supercapacitors

Recent Progress and Perspectives on Metal–Organic Framework-Based Electrode Materials for Metal-Ion Batteries and Supercapacitors

Nitrogen-Doped Porous Carbons Derived from Peanut Shells as Efficient Electrodes for High-Performance Supercapacitors.

The doping of porous carbon materials with nitrogen is an effective approach to enhance the electrochemical performance of electrode materials. In this study, nitrogen-doped porous carbon derived from peanut shells was prepared as an electrode for supercapacitors. Melamine, urea, urea phosphate, and ammonium dihydrogen phosphate were employed as different nitrogen dopants. The optimized electrode material PA-1-1 prepared by peanut shells, with ammonium dihydrogen phosphate as a nitrogen dopant, exhibited a N content of 3.11% and a specific surface area of 602.7 m2/g. In 6 M KOH, the PA-1-1 electrode delivered a high specific capacitance of 208.3 F/g at a current density of 1 A/g. Furthermore, the PA-1-1 electrode demonstrated an excellent rate performance with a specific capacitance of 170.0 F/g (retention rate of 81.6%) maintained at 20 A/g. It delivered a capacitance of PA-1-1 with a specific capacitance retention of 98.8% at 20 A/g after 5000 cycles, indicating excellent cycling stability. The PA-1-1//PA-1-1 symmetric supercapacitor exhibited an energy density of 17.7 Wh/kg at a power density of 2467.0 W/kg. This work not only presents attractive N-doped porous carbon materials for supercapacitors but also offers a novel insight into the rational design of biochar carbon derived from waste peelings.