High-performance Pseudocapacitors Research Articles

Effects of surfactants on the morphologies, structures, and electrochemical activities of WO3/Ag2O nanocomposites for supercapacitor electrodes

For energy storage, supercapacitors have been extensively developed. Among them, pseudocapacitors that use faradaic reactions of conductive polymers and transition metal oxides exhibit high electrochemical performance. In this study, WO3-based electrodes for high-performance pseudocapacitors were designed with Ag2O and various surfactants, with the aim to extend of the potential range and shape control of WO3 crystals. The WO3/Ag2O nanocomposites were prepared on a carbon cloth via chemical bath deposition with different types of surfactants: cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Pluronic F-127. Both Ag and the surfactants affected the morphology of the WO3 crystals; their crystal sizes were decreased, and the crystallinity was improved. The specific capacitance of the WO3/Ag2O nanocomposite was 621 F/g at 5 mV/s, whereas that of WO3 was 397 F/g. Furthermore, the specific capacitance of the nanocomposites increased with the use of surfactants: 960 F/g for WO3/Ag2O@Pluronic F-127, 641 F/g for WO3/Ag2O@CTAB, and 846 F/g for WO3/Ag2O@SDS at 5 mV/s. WO3/Ag2O@Pluronic F-127 had superior capacitance and exhibited a charge/discharge capacitance retention rate of 135 % after 2000 cycles at 5 A/g. The symmetric electrode configuration of WO3/Ag2O@Pluronic F-127 exhibited a maximum energy density of 85 W h kg−1 and a power density of 670 W kg−1. These results highlight the significant potential of the WO3/Ag2O@Pluronic F-127 nanocomposite electrode for future energy storage devices.

Deposition of polyaniline nanofibers on activated carbon textile for high-performance pseudocapacitors

Deposition of polyaniline nanofibers on activated carbon textile for high-performance pseudocapacitors

Synthesis of NiMn2O4/PANI nanosized composite with increased specific capacitance for energy storage applications.

Polyaniline (PANI) stands out as a highly promising conducting polymer with potential for advanced utilization in high-performance pseudocapacitors. Therefore, there exists a pressing need to bolster the structural durability of PANI, achievable by developing composite materials that can enhance its viability for supercapacitor applications. In this particular study, a pioneering approach was undertaken to produce a novel NiMn2O4/PANI supercapacitor electrode material. A comprehensive array of analytical techniques was employed to ascertain the structural configuration, morphology, oxidation states of elements, composition, and surface characteristics of the electrode material. The electrochemical evaluation of the NiMn2O4/PANI composite shows a specific capacitance (Cs) of 1530 ± 2 F g-1 at 1 A g-1. Significantly, the composite material displays an outstanding 93.61% retention of its capacity after an extensive 10 000 cycles, signifying remarkable cycling stability, while the 2-electrode configuration reveals a Cs value of 764 F g-1 at 5 mV s-1 and 826 F g-1 at 1 A g-1 with a smaller charge transfer resistance (Rct) value of 0.67 Ω. Chronoamperometric tests showed excellent stability of the fabricated material up to 50 h. This significant advancement bears immense promise for its potential implementation in high-efficiency energy storage systems and heralds a new phase in the development of supercapacitor technology with improved stability and performance metrics.

Rich-grain-boundary Ni–Co–Se nanowire arrays for fast charge storage in alkaline electrolyte

In this work, the one-dimensional (1D) Ni–Co–Se nanowire arrays with rich grain-boundaries were prepared through the solvothermal method and gas-phase selenizaiton. The results showed that the structure and crystallization of the Ni–Co–Se nanowire arrays could be modulated through the optimization of selenizaiton time. The optimal Ni–Co–Se electrode sample displayed an area specific capacitance of 242.6 μAh cm−2 at 30 mA cm−2 with a current retention rate of 68.34%. The assembled Ni–Co–Se/Active carbon (AC) electrode-based asymmetric supercapacitor (ASC) showed the area specific capacitances of 329.2 μAh cm−2 and 225.8 μAh cm−2 at 3 mA cm−2 and 30 mA cm−2, respectively. A 73.33% retention rate of capacitance was observed after 8000 charge/discharge cycles. Besides, the further fabricated all-solid ASC delivered the power densities of 342.94 W kg−1 and 3441.33 W kg−1 at the energy densities of 37.62 Wh kg−1 and 25.81 Wh kg−1, respectively. Those results suggested the potentials of the obtained Ni–Co–Se nanowire arrays as electrode material for the high-performance pseudocapacitors.

Epitaxial growth of NixCo3-xS4 nanoflakes from co-based Prussian blue analog for high-performance pseudocapacitors

In this work, a NixCo3-xS4/PBA (Prussian blue analogue) heterostructure is obtained via a facile epitaxial growth method, forming a flower-like structure with NixCo3-xS4 nanoflakes standing independently on PBA. The 2D NixCo3-xS4 nanoflakes can provide sufficient reaction sites for charge storage, while the PBA core can facilitate quick ion transportation during charge/discharge process. Moreover, it has been shown that the growth of NixCo3-xS4 nanoflakes from PBA is a time-dependent reaction that could regulate the electronic state density of Co, Ni and S along the interface of NixCo3-xS4 and PBA. EELS and DFT calculations reveal that the formation of heterogeneous interface between NixCo3-xS4 nanoflakes and PBA results in an electron deficient region of NixCo3-xS4, which benefits the adsorption and reaction of OH– on NixCo3-xS4. With the structural and compositional merits, the NixCo3-xS4/PBA obtained with reacting for 7 h exhibits the superior specific capacitance and good rate capability with retaining 91.5 % of initial capacitance as well as quick charge response. The assembled NixCo3-xS4/PBA//AC asymmetric supercapacitor exhibit an energy density of 52.2 Wh kg−1, which could light 14 LED lamps with maintaining the brightness for 5 min. Therefore, the design of 3D NixCo3-xS4/PBA and the systematical investigation on the structural evolution as well as the concomitant electron configuration regulation may not only inspire the design of high-performance electrode materials for supercapacitors, but also be valuable for understanding the charge storage mechanism on heterostructures.

Shuttling-free redox electrolyte locks proton-conductive polyoxometalates in porous carbon for high-performance pseudocapacitors

Redox electrolytes are highly attractive to bring conventional carbon-based supercapacitors the additional pseudocapacitance; however, shuttling of redox species remains a severe issue restricting the potential applications of redox electrolytes. Here, we report a new phosphotungstic acid-containing redox electrolyte for carbon-based supercapacitors, which shows the shuttling-free feature by locking the polyoxometalate mediators in the porous carbon electrode. Impressively, the porous carbon electrode affords a remarkable specific capacitance of 885.7 F g−1 at 5 mV s−1 in the phosphotungstic acid-added electrolyte, triple that in the additive-free H2SO4 electrolyte (290.2 F g−1). Profiting from the unique Grotthuss proton conduction of phosphotungstic acid, the porous carbon electrode achieves the dramatic rate capability in our redox electrolyte (i.e., 567.7 F g−1 at 200 mV s−1). Moreover, the assembled supercapacitor device affords a specific energy of 52.3 Wh kg−1 and long-term cycling stability (93.7% over 5000 cycles). This study highlights the superiority of the polyoxometalate additive for redox electrolytes in developing advanced supercapacitors integrating high energy density, excellent rate performance, and electrochemical durability.

Facile preparation of Ga-doped ZnO nanostructures by composite-hydroxide-mediated synthesis route for high-performance pseudocapacitors

Facile preparation of Ga-doped ZnO nanostructures by composite-hydroxide-mediated synthesis route for high-performance pseudocapacitors

Binder-free NiO/CuO hybrid structure via ULPING (Ultra-short Laser Pulse for In-situ Nanostructure Generation) technique for supercapacitor electrode

Developing a cost-effective pseudocapacitor electrode manufacturing process incorporating binder-free, green synthesis methods and single-step fabrication is crucial in advancing supercapacitor research. This study aims to address this pressing issue and contribute to the ongoing efforts in the field by introducing ULPING (Ultra-short Laser Pulse for In-situ Nanostructure Generation) technique for effective design. Laser irradiation was conducted in ambient conditions to form a CuO/NiO hybrid structure providing a synergistic contribution to the electrical behavior of the electrode. Mainly, the effects of surface morphology and electrochemical surface because of tuning laser intensity were analyzed. The samples demonstrated high oxide formation, fiber generation, excellent porosity, and ease of ion accessibility. Owing to a less than 10-min binder-free fabrication method, the electrochemical performance of the as-fabricated electrode was 25.8 mC cm−2 at a current density of 1 mA cm−2 proved to be excellent. These excellent surface properties were possible by the simple working principle of pulsed laser irradiation in ambient conditions and smart tuning of the important laser parameters. The CuO/NiO electrode demonstrates excellent conductivity and rewarding cyclic stability of 83.33% after 8000 cycles. This study demonstrates the potential of the ULPING technique as a green and simple method for fabricating high-performance pseudocapacitor electrodes.

Hierarchically Electrodeposited Spinel Cobalt Oxide Nanoflakes on 3D Graphene Oxide Framework as a High-Performance Pseudocapacitor Electrode

Hierarchically Electrodeposited Spinel Cobalt Oxide Nanoflakes on 3D Graphene Oxide Framework as a High-Performance Pseudocapacitor Electrode

Co/N Co-Doped MoS2 with High Pseudocapacitive Performance for Solid-State Flexible Supercapacitors

Herein, we demonstrate the enhanced pseudocapacitive performance of a MoS2-based flexible supercapacitor by the co-doping strategy of cations and anions. The MoS2 nanosheet arrays on carbon cloth are directly doped with N and Co atoms through a simple hydrothermal process. The obtained cation and anion co-modified MoS2 (N-Co-MoS2) shows improved electron transport efficiency and enhanced active sites for MoS2. According to the first-principles calculations, N-Co-MoS2 has a unique band structure and high electrical conductivity. As expected, N-Co-MoS2 shows higher capacitive performance with 5072.5 mF cm–2 and a better cycle life (retaining 100% capacitance after 10,000 cycles) than pure MoS2. Furthermore, a solid-state flexible N-Co-MoS2 supercapacitor device is fabricated to demonstrate excellent mechanical stability with a specific capacitance of 3236 mF cm–2 and a stable cycle capacitance of 75.56% after 5000 cycles. In our work, we have provided a reference for preparing MoS2-based materials with good supercapacitive performance.

A Novel Oxidation–Reduction Route for the Morphology-Controlled Synthesis of Manganese Oxide Nanocoating as Highly Effective Material for Pseudocapacitors

In recent years, pseudocapacitors have been receiving much attention as low-cost and safe energy storage technology for emerging applications in flexible and safe devices. However, creating high-energy-density electrode materials is now the main limit for high-performance pseudocapacitors. In this work, we propose a novel reduction route for the synthesis of uniform MnO2 nanocoating with porous morphology on nickel foam via the SILD method as electrode material for high-effective pseudocapacitors. The obtained nanocoatings were characterized by SEM, TEM, EDX, XRD, XPS, and electrochemical techniques. Comparisons of MnO2 coatings were conducted to obtain the reduction and oxidative routes of synthesis. The influence of the oxidation–reduction reaction type on the structures, morphologies, and capacity performance of manganese oxide was investigated. The results show that the nanocoatings synthesized via the reduction route were formed of amorphous uniform ultra-thick coating MnO2 with a porous morphology of “nanoflakes.” Due to the unique morphology and uniform coating of nanosized manganese oxide, electrodes based on this process have shown a high specific capacity (1490 F/g at 1 A/g) and excellent cycling stability (97% capacity retention after 1000 charge–discharge cycles).

Microwave-assisted fabrication of SnO2 nanostructures as electrode for high-performance pseudocapacitors

A microwave irradiation technique was utilized to fabricate SnO2 nanostructured electrodes for high-performance supercapacitors. The as-synthesized materials were investigated and analyzed using various characterization instruments. The outcomes emphasized the synthesis of pure tetragonal-structured SnO2 in the rutile phase. The N2-adsorption-desorption analysis demonstrated that the produced SnO2 with a maximum wide distribution of 18.4 nm pore diameter and a 0.198 cm3 g−1 pore volume. Furthermore, the electrochemical performance of annealed SnO2 nanostructured was enhanced compared with pristine SnO2. The as-prepared electrode of SnO2 delivered the maximum specific capacitance and specific capacity of 407 F g−1 and 163 C g−1, respectively, at 1 A g−1. A hybrid supercapacitor cell was designed for a real application utilizing the as-synthesized SnO2 as cathode, whereas activated carbon served as the anode. This result led to supplying remarkable specific energy of 34 Wh kg−1 at a specific power of 773 W kg−1 and delivering an outstanding cycling performance retaining 87 % of its initial capacity even after 3000 charge/discharge cycles. These superior electrochemical features suggest that the SnO2 nanostructured could be employed as active materials in supercapacitor systems with a high energy density.

Enhanced Pseudocapacitance of the LaNiO3 Perovskite in p‐Phenylenediamine as Redox‐Active Electrolyte

AbstractPerovskite oxides are well known for their excellent properties such as catalytic activity, oxygen ion mobility and structure stability. These properties make it a most suitable material for energy storage devices like fuel cells, batteries and supercapacitors. In the present work, LaNiO3 perovskite was synthesized using the sol‐gel method and its morphological parameters were characterized by XRD, SEM and FTIR. The anion‐intercalated pseudocapacitive nature of LaNiO3 powder was studied in 2M KOH as well as in the mixture of 2M KOH with p‐phenylenediamine (PPD) as an alkaline aqueous and redox‐active electrolyte respectively. Electrochemical performance characteristics cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) of LaNiO3 has shown pseudocapacities of 300.60 Fg−1 at a scan rate of 5 mV s−1 and 440 F g−1 at a current density of 1 A g−1 in KOH+PPD electrolyte. Furthermore, a symmetrical pseudocapacitor has been fabricated using LaNiO3 as electrode active material with 2M KOH+PPD as an redox‐active electrolyte. The device delivered an energy density of 13.75 Wh kg−1 at the power density of 500 W kg−1 at a potential of 1 V. This excellent performance may be due to the synergic effect of both redox active electrode (LaNiO3) and electrolyte (KOH+PPD) that together demonstrated a great combination for high performance pseudocapacitors for future applications.

CuO induced effects on the electrochemical properties of (In2O3)1-xCuOx nanocomposites for supercapacitor flexible electrode materials

• Novel (In 2 O 3 ) 1-x CuO x heterostructure nanocomposites with different concentration was fabricated through the surfactant-assisted co-precipitation method. • The electrochemical performance and electrochemical cycle stability of all the prepared samples were assessed over the carbon cloth (CC) electrode. • The (In 2 O 3 ) 0.5 (CuO) 0.5 was demonstrated higher capacitance 883 F/g at 1A/g than all other samples. • Approximately 83.5% capacity retention after 6000 GCG tests was measured for (In 2 O 3 ) 0.5 (CuO) 0.5 . Recent research on electrochemical energy storage devices has shown that their specific capacities, cyclic-lives, as well as rate performances, are chiefly controlled by their electrodes. Therefore, a key challenge for 21st-century material researchers is to seek out novel electrode materials with improved crystal structures, excellent specific capacities and better electronic conductivities, in order to fabricate a highly efficient energy storage system. To address this concern (In 2 O 3 ) 1-x CuO x (where x = 0, 0.1, 0.3, 0.5, 0.7, 1) heterostructure nanocomposites have been prepared through the surfactant-assisted co-precipitation strategy. The nature of the atomic and molecular interactions, chemical compositions, textures and shapes of the synthesized nanocomposites have been investigated in detail. In this study, the novel composite materials have been supported over carbon cloth (CC) to produce flexible working electrodes. It has been found that the electrode with a particular composition of (In 2 O 3 ) 0.5 (CuO) 0.5 -over-CC has demonstrated superior capacitance (883 F/g at 1 A/g), improved electrochemical and cycle stability (83.5 % after 6000 GCD tests) and a higher rate capability (708 F/g at 5 A/g) than all other fabricated nanocomposite-based flexible electrodes. The electrode's improved electrochemical activity is attributed to its flexible design, higher electronic conduction, non-resistive current collector behaviour and unique nanoarchitecture. These versatile and simple-to-prepare nanocomposites are potential candidates as electrodes for high-performance pseudocapacitors nanodevices.

Engineering oxygen-deficient nanocomposite comprising LaNiO3-δ and reduced graphene oxide for high-performance pseudocapacitors

Aiming at a high performance pseudocapacitive electrode - an oxygen-deficient nanocomposite comprising reduced graphene oxide-Lanthanum nickelate LaNiO3 (rGO-LNO) was synthesized using a facile binder-free approach. The structural identity and the phase purity of the nanocomposite were verified by X-ray diffraction and electron microscopy studies coupled by the inputs from Raman scattering. The assistance of rGO in the amplification of oxygen vacancies in rGO-LNO relative to LNO was confirmed from X-ray photoelectron spectroscopy (XPS). Maximum specific capacitance of 920 F g−1 at 1 A g−1 current density in 6 M KOH solution in a three-electrode set up was observed. An excellent long-term cycling efficiency of over 99 % even at a high current density of 10 A g−1 in solid-state-symmetrical setup. Analysis of self-discharge and leakage current parameters concluded sturdy electrode dynamics. Deconvolutions of cyclic voltammograms were suggestive of majorly bulk conduction over diffusive kinetics. In summary, LNO facilitates a faster electron transfer rate and while rGO allows the penetration of the electrolytes into the bulk matrix, and allows more effective utilization of the electrode materials via. an efficient ion-exchange.

Water-in-Salt Ambipolar Redox Electrolyte Extraordinarily Boosting High Pseudocapacitive Performance of Micro-supercapacitors

Water-in-Salt Ambipolar Redox Electrolyte Extraordinarily Boosting High Pseudocapacitive Performance of Micro-supercapacitors

Unique core-shell Co2(OH)2CO3@MOF nanoarrays with remarkably improved cycling life for high performance pseudocapacitors

Binder-free composite electrode material consisted of cobalt hydroxycarbonates (Co2(OH)2CO3) and bimetallic metal-organic-framework (NiCo-MOF) is facilely prepared for the first time through a hydrothermal-solvothermal combined method. The composite Co2(OH)2CO3@MOF presents a unique core-shell architecture, which endows remarkable superiority such as great surface area, short diffusion pathway and component synergy effects, leading to splendid supercapacitor performance. The optimal composite electrode exhibits ultrahigh specific capacitance (3232 F g−1 at 1 A g−1), good rate capability and outstanding cycle life (84.1% after 5000 cycles). In addition, an asymmetric supercapacitor (ASC) device Co2(OH)2CO3@MOF-2//AC (active carbon) delivers a high energy density (55.2 W h kg−1 @ 0.8 kW kg−1) and excellent cycle life (89.2% after 6000 cycles). These values are comparable to or even better than the recently reported related electrode materials in literatures (Table S1), demonstrating the prospect for future high performance energy storage devices. The smart strategy reported here can also be promoted to other metal hydroxycarbonates with advanced hierarchical core-shell structures for high performance electrochemical devices.

Temperature-induced Hollow Hierarchical NiCo2O4 Microspheres for High Performance Pseudocapacitors

Temperature-induced Hollow Hierarchical NiCo2O4 Microspheres for High Performance Pseudocapacitors

NiO nanoparticles/graphene nanocomposite as high-performance pseudocapacitor electrodes: Design and implementation

A simple hydrothermal approach was used to successfully fabricate NiO/G nanocomposites. Since the addition of nickel oxide nanoparticles (NiO) to graphene instead of conducting polymeric materials produces better capacitances and improved capacity retention. Graphene-based inorganic composites have been attracting more and more attention. The as prepared NiO/G nanocomposite is characterized by XRD, TEM, Raman, XPS and nitrogen adsorption/desorption. It is demonstrated that NiO nanoparticles adorn graphene sheets to generate hierarchical nanostructures with rich porosity (33.8 nm) and substantial specific surface area (51 m2 g−1). Electrochemical characterization demonstrate that the mesoporous graphene/NiO can deliver a specific capacitance of 632 F g−1 at a current density of 2 Ag−1 and have a capacitance retention of 99.7% at 2Ag−1 after 6000 continuous charge–discharge cycles. In addition, the ASC constructed from NiO/G shows excellent energy density (30.56 Whkg−1), excellent power density (2800 Wkg−1) and impressive cycle performance (capacitance retention after 6000 cycles is approximately 92.7%). This strategy aids in the fabrication and utilization of hybrid nanocomposite in high-geared reversible supercapacitors.

Quinone-Based Imide Conjugated Microporous Polymer-Reductive Graphene Oxide Composite for High Performance Pseudocapacitor

Quinone-Based Imide Conjugated Microporous Polymer-Reductive Graphene Oxide Composite for High Performance Pseudocapacitor