Electrode Material For High-performance Supercapacitors Research Articles

Synthesis of Bi2O3/hierarchical porous carbon composites for supercapacitor application

Bismuth oxide (Bi2O3) is considered a promising electrode material for supercapacitors boasting a high theoretical capacity. Its weak conductivity, limited rate performance, and poor cycling stability have significantly hindered practical applications. In this work, a simple precipitation and calcination method was used to prepare Bi2O3/hierarchical porous carbon composite materials (Bi2O3/N-HPC). The biomass-derived hierarchical porous carbon precursor was prepared through a process involving nitrogen doping and chemical activation. Comprehensive physical and chemical structure characterization results showed that a large number of spherical Bi2O3 particles were dispersed on the surface of the carbon material, providing numerous active sites for electrochemical reactions. The nitrogen-doped hierarchical porous carbon scaffold provided rapid pathways for charge transfer and restricted the aggregation of Bi2O3 particles. As an electrode material in a 6 M KOH electrolyte, Bi2O3/N-HPC exhibited a specific capacitance of 684.9 F g−1 at a current density of 0.5 A g−1, and even at an increased current density of 20 A g−1, the specific capacitance remained at 500.0 F g−1. After 10,000 cycles of charge and discharge, the capacitance retention rate of the Bi2O3/N-HPC electrode reached 85.2 %. This research offers a promising pathway for the development of high-performance supercapacitor electrode materials.

An-All-Solid State Supercapacitor Device from E-Waste Derived Activated Carbon

Recycling solid waste has substantial economic and environmental advantages. Electronic waste (e-waste) has the complex intrinsic trait of combining metals and non-metals contained in the same waste stream, which limits the recycling technologies that are now available for it. Much interest has been created by the outstanding surface and conductive qualities of carbon-based materials made from waste. In this article, we transformed e-waste (end of life keyboard) into highly porous activated carbon for its application as high-performance electrode material for supercapacitor. The as-synthesized activated carbon is characterized via material characterization techniques such as XRD, Raman, FTIR and BET. E-waste derived porous carbon (EWPC) rendered decent electrochemical performance in 1M H2SO4 electrolyte. Furthermore, an-all-solid-state symmetric supercapacitor device (EWPC//EWPC) has been fabricated and recorded convincing results in terms of energy density, power density, and cyclic stability. Hence, this study open up new avenues for recovering and creating high-performance, environmentally friendly materials from discarded e-wastes.

Morphology-controllable synthesis of bimetallic oxide Bi2Fe4O9 as novel electrode materials for high-performance supercapacitors

Supercapacitors have grabbed a lot of limelight and have been under extensive scrutiny by researchers for their advantages over competitors, such as high power density, long-term cycle life, accelerated charging and discharging, security, and environmental sustainability. Herein, the hydrothermal combination with co-precipitation approach is effectively used to create Bi2Fe4O9 particles with various morphologies through controlling the concentrations of NaOH, and they show significant discrepancies in their electrochemical characteristics. The chamfered square plate-like Bi2Fe4O9 particles (Bi2Fe4O9–3) obtained at a NaOH concentration of 12 M demonstrate pseudocapacitive or battery-like behavior in a three-electrode system and exhibited optimum electrochemical properties, displaying a mass-specific capacitance of 443.8 F g−1 at 1.0 A g−1. In terms of electrochemical characteristics and long-term cycling stability, the Bi2Fe4O9–3 sample also displays an extraordinary Coulombic efficiency of 98.87 % and capacitance retention rate of 142 % after completing 5000 cycles of galvanostatic charge-discharge. Moreover, the self-assembled asymmetric supercapacitor device has an energy density of 21.11 Wh kg−1 at a power density of 424.26 W kg−1. Bi2Fe4O9–3 has been meticulously fabricated as an innovative and inimitable electrode material that manifests brilliant electrochemical properties, rendering it prospective for progressive application in the supercapacitors realm by researchers in the future.

Supramolecular polymers with dual energy storage mechanism for high-performance supercapacitors

In this paper, we prepared the supramolecular polymers (MWCNT-APP-s) with a dual energy storage mechanism as the electrode materials by the coordination of four transition metal ions with the small molecule chelator (APP) and functionalized carbon nanotubes, respectively. Among four MWCNT-APP-s, MWCNT-APP-Fe has the characteristics of moderate micropore/mesopore, significant hydrophobicity, redox property and functional groups. Interestingly, the redox reaction of Fe3+/Fe2+ and -CN-/-CN- transformation give MWCNT-APP-Fe an energy storage basis of pseudocapacitance, while MWCNTs and the micro/mesopore structure in MWCNT-APP-Fe provide a double-layer energy storage platform. As expected, on base of the dual energy storage mechanism, the symmetric supercapacitor assembled with MWCNT-APP-Fe has a higher specific capacity (Cs, 421 F g−1 at 1 mV s−1) as well as a long-lasting stability of 94.8% capacity retention with 99% Coulombic efficiency after 10,000 cycles at 20 mV s−1. More notably, the relevant aqueous Zn2+ hybrid supercapacitor provides a high capacity (Cm) of 191 mAh g−1 at 0.5 A g−1 and a long duration of over 2000 cycles at 50 A g−1, with a capacity retention of 92.4%. In summary, MWCNT-APP-Fe with a dual energy storage mechanism enables a potential application as an electrode material for high-performance supercapacitor.

High-efficiency activated phosphorus-doped Ni2S3/Co3S4/ZnS nanowire/nanosheet arrays for energy storage of supercapacitors

Transition metal sulfides (TMS) have been considered as a promising group of electrode materials for supercapacitors as a result of their strong redox activity, but high volumetric strain of the materials during electrochemical reactions causes rapid structural collapse and severe capacity loss. Herein, we have synthesized phosphorus-doped (P-doped) Ni2S3/Co3S4/ZnS battery-type nanowire/nanosheet arrays as an advanced cathode for supercapacitor through a two-step process of hydrothermal and annealing treatments. The material has a one-dimensional nanowire/two-dimensional nanosheet-like coexisting microscopic morphology, which facilitates the exposure of abundant active centers and promotes the transport and migration of ions in the electrolyte, while the doping of P significantly enhances the conductivity of the electrode material. Simultaneously, the element phosphorus with similar atomic radii and electronegativity to sulfur may act as electron donors to regulate the electron distribution, thus providing more effective electrochemically active sites. In gratitude to the synergistic effect of microstructure optimization and electronic structure regulation induced by the doing of P, the P-Ni2S3/Co3S4/ZnS nanoarrays provide a superior capacity of 2716 F g−1 at 1 A/g, while the assembled P-Ni2S3/Co3S4/ZnS//AC asymmetric supercapacitor exhibits a high energy density of 48.2 Wh kg−1 at a power density of 800 W kg−1 with the capacity retention of 89 % after 9000 cycles. This work reveals a possible method for developing high-performance transition metal sulfide-based battery-like electrode materials for supercapacitors through microstructure optimization and electronic structure regulation.

Highly porous nanocarbons derived from fluorinated polyimide and metal organic framework for energy storage electrodes

In this study, porous nanocarbon is prepared by hybridizing metal–organic framework (MOF, ZIF-8 in this study) and fluorinated polyimide (fPI) and subsequent carbonization. The resulting nitrogen-doped nanocarbon has a considerable specific surface area as high as 1096 m2 g–1 and is thus utilized as an electrode material for high-performance supercapacitors. Particularly, the porous nanocarbon derived from the sample containing 10 wt% of ZIF-8 to fPI exhibits coexistence of nano- and mesopores, leading to enhanced mass transport and electrolyte ion diffusion across electrodes and high-rate performance at high specific current. It also retains its initial performance even after 4000 charging/discharging cycles and provide large specific energy (10.7 Wh kg−1) and power (5 kW kg−1). The incorporation of MOF with fPI enhances the porosity of porous carbons in terms of charge storage and thus this hybridization concept provides a vital platform for energy storage electrodes.

Biomass-based controllable morphology of carbon microspheres with multi-layer hollow structure for superior performance in supercapacitors

The electrochemical properties of corn starch (CS)-based hydrothermal carbon microsphere (CMS) electrode materials for supercapacitor are closely related to their structures. Herein, cetyltrimethyl ammonium bromide (CTAB) was used as a soft template to form the corn starch (CS)-based carbon microspheres with radial hollow structure in the inner and middle layers by hydrothermal and sol-gel method. Due to the introduction of multi-layer hollow structure of carbon microsphere, more micropores were produced during CO2 activation, which increased the specific surface area and improved the capacitance performance. Compared to commercial activated carbon, the four different morphologies of corn starch CMS had better electrochemical performances. Consequently, the proposed CO2–(CTAB)-CS-CS exhibits a high discharge specific capacitance of 242.5F/g at 1 A/g in three-electrode system with 6 M KOH electrolyte, better than commercial activated carbon with 208.5F/g. Moreover, excellent stability is achieved for CO2–(CTAB)-CS-CS with approximately 97.14 % retention of the initial specific capacitance value after 10,000 cycles at a current density of 2 A/g, while the commercial activated carbon has 86.96 % retention. This implies that the corn starch-based multilayer hollow CMS could be a promising electrode material for high-performance supercapacitors.

Heteroatoms co-doped multi-level porous carbon as electrode material for supercapacitors with ultra-long cycle life and high energy density

As a promising electrode material for supercapacitors, porous carbon has received widespread attention. However, taking into account of the capacitive performance, the cost and environmental protection, the practicability of the carbon previously reported is still unsatisfactory. Therefore, it is meaningful and challenging to develop a proper carbon material. In the present work, N, O, P co-doped porous carbon materials are prepared from poplar catkin biomass wastes with a two-step chemical activation method by using H3PO4 and K2CO3, separately. Specifically, the optimal HKPC-1-2.0 possesses a multi-level pore structure with an ultra-high specific surface area (2133 m2 g−1) and a suitable micropore percentage (52.8 %). As a result, HKPC-1-2.0 displays a specific capacitance of 296.2 F g−1 at 1.0 A g−1 in the three-electrode system by using 6.0 M KOH as electrolyte. More importantly, the symmetrical HKPC-1-2.0//HKPC-1-2.0 device exhibits a high capacity retention rate of 100.1 % even after 40,000 charge-discharge cycles at 1.0 A g−1. The co-doping of the heteroatoms and the hierarchical network with suitable pore size distribution are advantageous for the storage and transportation of ions, therefore leading to the encouraging capacitive performance. This work not only offers a low-cost and high-performance carbon electrode material for supercapacitors but also develops an environmentally-friendly strategy for effectively conversing biomass wastes to high value-added products.

Urchin-like structure and nanowire arrays of NiCo2O4/NiCoSe2 as a binder-free electrode material for high-performance supercapacitor

Hybrid structures targeted at high-performance electrochemical applications circumvent great challenges. Nanostructures with high porosity facilitating electrolyte penetration and providing fast ion and electron transfer are suitable candidates for constructing hybrid structured electrode materials. Here in, an architecture composed of nanowires and urchin-like structures of NiCo2O4 covered by NiCoSe2 nanosheets is successfully constructed on Ni foam through hydrothermal treatment in association with electrodeposition. The fabricated NiCo2O4/NiCoSe2 hybrid electrode demonstrates areal capacitance of 12.09 F cm-2 at current density of 5 mA cm-2, surpassing that of pristine NiCo2O4. Furthermore, the electrode evidences cycling stability with 87.6% capacitance retention over 3000 cycles. An asymmetric hybrid supercapacitor, assembled by the NiCo2O4/NiCoSe2 as a positive electrode and activated carbon as a negative electrode, represents areal capacitance of 3.07 F cm-2 at 5 mA cm−2. The as-fabricated device with excellent cycling stability (90.9% capacitance retention over 2000 cycles) delivers an energy density of 66.13 Wh kg-1 at a power density of 233 W kg-1. Our results convey a promising synthesis method of the core-shell structure of NiCo2O4/NiCoSe2 nanowire arrays for application in supercapacitors.

β-Cyclodextrin-Stabilized CuO/MXene Nanocomposite as an Electrode Material for High-Performance Supercapacitors.

Supercapacitors are the best energy storage systems due to their high power density, quick charge/discharge rate, and long-term reliability. In this study, β-cyclodextrin-stabilized CuO nanoparticles (CuO@βCD NPs) were synthesized through a simple reduction method and anchored on the surface of MXene nanosheets in three different proportions (1:1, 4:1, and 1:4) to obtain CuO@βCD/MXene nanocomposites through the wet-impregnation method. The formation of CuO@βCD NPs and their physicochemical characteristics were verified by XRD, XPS, FE-SEM, and HR-TEM analysis. The actual focus is on the evaluation of the electrochemical performances of CuO@βCD, MXene, and CuO@βCD/MXene nanocomposites for supercapacitor applications. The cyclic voltammetry and galvanostatic charge-discharge analysis revealed the pseudocapacitance and an improved specific capacitance of 1693.43 F g-1 at 0.90 A g-1 for the CuO@βCD/MXene (1:1) nanocomposite. The electrochemical impedance analysis displays superior electrical conductivity with a low charge transfer resistance value on incorporating CuO@βCD between the MXene layers. Furthermore, the CuO@βCD/MXene (1:1) nanocomposite exhibited improved long-term cycling stability by retaining 86% of its initial specific capacitance even after the 10,000th cycle at the current density of 4.54 A g-1. Based on the electrochemical performance, the CuO@βCD/MXene (1:1) nanocomposite proves its suitability as an electrode material for supercapacitor application with long-term cycling stability and rate capability.

Biomass waste-derived porous graphitic carbon for high-performance supercapacitors

Porous carbons possess considerable appeal and are in high demand as materials that can be produced from biomass waste. This study presents the transformation of Tectona grandis (Teak) sawdust into porous carbon materials, referred to as Tectona grandis sawdust-derived porous carbon (TPC), through a cost-effective FeCl3-assisted carbonization process, followed by a KOH activation. TPC samples were synthesized by carbonization at different temperatures (650–850 °C) and characterized comprehensively. Structural analysis via X-Ray diffraction (XRD), Raman, and Fourier Transform Infrared Spectroscopy (FTIR) revealed a progressive enhancement in graphitic structure and reduction of functional groups with increasing activation temperature. Field emission scanning electron microscopy (FESEM) displayed the development of intricate hollow tube-like porous networks in TPC-850, with the highest specific surface area (1767.66 m2/g) and pore volume (1.43 cm3/g). Electrochemical investigations showcased the superior performance of TPC-850 as a supercapacitor electrode due to its high graphitic nature, large surface area, and well-structured porosity. The galvanostatic charge-discharge (GCD) measurements exhibited a high specific capacitance of 572 F/g at 0.5 A/g in a 6 M KOH electrolyte. The high-frequency semicircle and low-frequency steeper region in electrochemical impedance spectroscopy (EIS) further indicated reduced resistance and enhanced ion diffusion in TPC-850. Significantly, TPC-850 demonstrated remarkable electrochemical cyclic stability, retaining 95.83 % of its initial capacity even after undergoing 4500 cycles at a scan rate of 500 mV/s. The findings underscore the viability of TPC-850 as a high-performance supercapacitor electrode material, providing insights into harnessing renewable resources for advanced energy solutions. This work highlights the potential of utilizing waste biomass for energy storage applications and demonstrates the feasibility of converting it into efficient porous carbon materials with substantial graphitization and porosity.

Sonochemical synthesis of battery-type ZnCo2O4 electrode material with huge specific surface area for advanced hybrid supercapacitors

Sonochemistry is a novel and efficient method for the synthesis of electrode materials within micro-/nano-scale. In this work, the ZnCo2O4 nanoparticles (NPs) and chain-like ZnCo2O4 nanostructures, namely ZnCo2O4–7.5 and ZnCo2O4–9.5, were sonochemically prepared by controlling the pH value of reaction system combined with an extra calcination. The ZnCo2O4–7.5 NPs exhibited a larger specific surface area (SSA) of 148.77 m2 g−1, and presented better electrochemical properties such as a high specific capacity (Cs) of 331.2C g−1 under 2 A g−1 along with 82.5 % rate performance at 10 A g−1. As for the ZnCo2O4–9.5 nanostructure, it delivered an inferior Cs of 274.8C g−1 and showed a moderate rate capability with 75.6 % capacity retention, accordingly. The hybrid supercapacitor (HSC) device was assembled using such ZnCo2O4–7.5 NPs (ZnCo2O4–9.5 nanostructure) as cathode and activated carbon (AC) as anode to explore the application potential in the field of electrochemical energy storage. After 7000 cycles at the current density of 8 A g−1, both ZnCo2O4–7.5//AC and ZnCo2O4–9.5//AC HSCs showed outstanding cyclic stabilities with 100.4 % and 105.1 % of initial capacity retention, respectively. Meanwhile, the ZnCo2O4–7.5//AC HSC delivered a high energy density (Ed) of 38.1 W h kg−1 at the power density (Pd) of 1002.0 W kg−1, and it could still hold 26.3 W h kg−1 at the higher Pd of 9136.5 W kg−1. In contrast, the ZnCo2O4–9.5//AC HSC presented a slightly inferior Ed of 36.8 W h kg−1 at 1104.7 W kg−1. The both types of ZnCo2O4–7.5 and ZnCo2O4–9.5 electrode materials demonstrate excellent electrochemical property, and they can be expected to show brilliant application potential in the field of electrochemical energy storage & conversion when served as electrode materials for high-performance hybrid supercapacitors.

Graphene nanoflake-self stabilized dispersion polymerized PANI hybrids as efficient, binder-free electrode materials for high-performance flexible symmetric supercapacitors

In this study, we prepared hybrid electrodes of self-stabilized dispersion polymerized (SSDP) polyaniline (PANI) and graphene nanoflakes by a facile solution intercalation approach. Unlike the conventional electrode preparation methods, the SSDP PANI dispersion was prepared by adopting the secondary doping method. The preparation of hybrid electrodes by a unique combination of these methods eliminates the use of binders and imparts excellent electrochemical properties to these electrodes due to synergistic effects. The optimized electrode (PG 2:1) demonstrates a specific capacitance of 454.9 F g−1 at a current density of 0.5 A g–1 and the symmetric supercapacitor using this electrode, achieved an energy density of 33.2 Wh kg−1 at a power density of 1 kW kg−1. Furthermore, even at a high-power density of 10 kW kg−1, the device delivers an energy density of 25.4 Wh kg−1. Interestingly, the symmetric supercapacitor retains 89.2 % of its initial capacitance even after 10,000 continuous charge–discharge cycles at a current density of 5 A g–1. The performance of these devices was also tested for different bending angles and was found to exhibit excellent stability. The superior performance of this hybrid electrode offers significant potential for the development of efficient binder-free flexible supercapacitors for portable and wearable devices.

Biomass-based porous carbon from trachycarpus fortunei silk with the hierarchical oxygen-enriched structure for high performance flexible all-solid-state supercapacitor

Hierarchical porous carbons with diverse pore scales are commonly chosen as electrode materials for high-performance supercapacitors due to their excellent electrochemical properties. Herein, a novel synthetic method, dilute H2SO4 pretreatment coupling with subsequent KOH activation, is adopted to prepare hierarchical oxygen-enriched porous carbon using trachycarpus fortunei silk (TFSPC) waste as the raw material. The optimized TFSPC2 possesses a 2049 m2 g−1 specific surface area, 1.58 cm3 g−1 total pore volume, and 22.54 at% oxygen-containing doping. Benefiting from such characteristics, the TFSPC2 electrode exhibits an excellent specific capacitance of 469 F g−1 at 0.5 A g−1 and remarkable cycling stability of only 4.94% capacitance decay even after 20000 uninterrupted cycles in a 6 M KOH electrolyte. Furthermore, the assembled flexible symmetric supercapacitor device TFSPC2//TFSPC2 achieves a high energy density of 14.60 Wh kg−1 in a potential range of 0–1.3 V when the power density is 320 W kg−1. More importantly, the TFSPC2//TFSPC2 device demonstrates superior mechanical flexibility and maintains 88.70% capacity retention even through 2000 cycles (90°) of reduplicative bending/recovering. The research provides a low-cost, green, and renewable strategy for the synthesis of hierarchical porous carbons for supercapacitors.

A manganese oxide/biomass porous carbon composite for high-performance supercapacitor electrodes

Supercapacitors are an excellent energy storage device with broad application prospects in the new energy market. However, the low energy density of carbon-based materials severely limits their commercialization. In this study, a manganese oxide/biomass porous carbon composite with high energy density was prepared from soybean straw by the strategy of KOH activation to form porous structure and hydrothermal method to introduce manganese oxides as pseudocapacitors. The prepared composite possesses a high specific capacitance of 482 F g–1 at a current density of 0.5 A g–1. In addition, the supercapacitors assembled with the composite as electrode sheets have an energy density of up to 14.5 Wh kg–1 at a power density of 250 W kg–1. And the supercapacitors enable the light-emitting diode emit light continuously for 40 s. The successful preparation of the manganese oxide/biomass porous carbon composite provides a feasible method for the design and synthesis of high-performance supercapacitor electrode materials.

N-doped porous carbon network anchoring on hollow wooden carbon fibers for high-performance electrode materials in supercapacitors

N-doped porous carbon network anchoring on hollow wooden carbon fibers for high-performance electrode materials in supercapacitors

Porous activated carbon derived from petroleum coke as a high-performance anodic electrode material for supercapacitors

Porous activated carbon derived from petroleum coke as a high-performance anodic electrode material for supercapacitors

Facile preparation of CoMoO4/NiCo2O4 nano-sphere anode materials and their performance in asymmetric supercapacitors

CoMoO4/NiCo2O4 electrodes with a three-dimensional nano-sphere structure have been successfully prepared by a combination of hydrothermal and calcination methods. The electrode material exhibits a high specific capacitance of 1175 F g−1 at 1 A/g, excellent multiplicative performance (74.2 % capacity at 15 A/g) and good cycling stability (85.9 % specific capacitance retention after 10,000 cycles). The asymmetric supercapacitor was constructed using activated carbon (AC) as the negative electrode, showing excellent energy density (27.7 wh kg−1) and power density (806 W kg−1). It also has an extremely long operating life, maintaining a specific capacitance of 78.3 % after 5000 cycles at current densities up to 6 A/g. The results indicate that the synthesized mixed transition metal oxides CoMoO4/NiCo2O4 are promising as composite electrode materials for high-performance asymmetric supercapacitors.

Facile synthesis and electrochemical study of NiMnO3/CNT/PANI ternary hybrid as a high-performance supercapacitor electrode material

Facile synthesis and electrochemical study of NiMnO3/CNT/PANI ternary hybrid as a high-performance supercapacitor electrode material

Perovskite-type samarium cobalt oxide adorned hexagonal tungsten sulfide nanocomposites as a high-performance electrode material for symmetric supercapacitors

Perovskite-type samarium cobalt oxide adorned hexagonal tungsten sulfide nanocomposites as a high-performance electrode material for symmetric supercapacitors