Asymmetric Capacitor Research Articles

Facile synthesis of MWCNT hexagonal needles grown on interconnected honeycombs like MnCo2O4/MnO2 nanoporous electrode for high-performance asymmetric supercapacitor

The construction of a honeycomb-like structure composed of MnCo2O4/MnO2was effectively achieved using a combination of hydrothermal processing and heat treatment. The whole surface of the MnCo2O4/MnO2 honeycomb is coated with neatly arranged hexagonal nano needles made of MWCNT, leading to a substantial enhancement in the specific surface area. At 1 A/g, the supercapacitor electrode composed of MnCo2O4/MnO2@MWCNT composite exhibited an exceptional specific capacitance of around 1539 F/g. Furthermore, it maintained approximately 95.5 % of its capacity even after undergoing 10,000 cycles. The asymmetric capacitor device, with MnCo2O4/MnO2@MWCNT and AC electrode, has a power density of 1537.8 W kg−1 and an energy density of 48.78 Wh kg−1. The MnCo2O4/MnO2composite exhibits exceptional rate performance, significant capacitance, and excellent cycle performance due to the synergistic effect between MnCo2O4/MnO2 and MWCNT, as well as the high specific surface area and unique structure. Consequently, it presents a viable option for the advancement of high-efficiency electrochemical super capacitors in the next generation.

Construction of MWCNT nanoneedles decorated on NiCo2O4/MnO2 composite electrodes with high energy density for asymmetric capacitor applications

In this work, a nanocomposite electrode of MWCNT nanoneedles decorated on spheres like NiCo2O4/MnO2 on NF is designed by a hydrothermal method and ultrasonication technique. The resulting interconnected network has an open geometric structure and a porous nature. Furthermore, NiCo2O4/MnO2@MWCNT's greater surface area (174.2 m2/g) promoted ion diffusion and transport, which enhanced specific capacitance. Consequently, this hybrid composite demonstrates a remarkable specific capacitance of 1728 F/g at 1 A/g, in addition to outstanding durability, maintaining 93.83 % of its capacitance after 10,000 cycles. A NiCo2O4/MnO2/MWCNT hybrid composite is used as the positive electrode, while Activated carbon serves as the negative electrode in an asymmetric supercapacitor. This configuration achieves an energy density of 55.8 Wh kg−1 and a maximum power density of 4099 W kg−1. This outcome indicates that the NiCo2O4/MnO2/MWCNT hybrid composite shows promise as highly efficient electrodes in energy storage devices.

Hierarchical NiCo2O4 needle-like heterostructure arrays anchored on WO3 as high- performance asymmetric supercapacitors for energy storage applications

The current work employs a novel approach to construct a composite nanostructure to improve the capacitive performance of a supercapacitor device. The work involved preparing cube-shaped WO3 particles and depositing them onto the surface of NiCo2O4 needles using a microwave technique. The structure of the composites enables efficient paths for ion transport and electron diffusion in supercapacitors. The hybrid composite electrode demonstrates a specific capacitance of 716 F g−1 at a current density of 5 Ag−1. The asymmetric capacitor device, which utilizes NiCo2O4@WO3 as the positive electrode and AC as the negative electrode, exhibits an energy density of 48.57 Wh kg−1 at a power density of 1120 W kg−1. In addition, the NiCo2O4@WO3//AC device has a favourable cycle life, maintaining 85.7 % of its capacitance retention after 10,000 cycles. The findings demonstrate the potential of NiCo2O4@WO3//AC to be used in the development of advanced hybrid electrodes for improved supercapacitors.

Exploring polyaniline nanofiber synthesis at vegetable oil-water interfaces for high-performance hybrid electrochemical capacitors

Polyaniline (PANI) nanofibers are synthesized at five different vegetable oil-water interfaces by a modified interfacial polymerization method. A series of syntheses is performed to study the effect of vegetable oil- water interfaces on the sizes, morphologies and corresponding electrochemical performances of resultant PANI nanofiber samples. Five PANI nanofiber samples are synthesized and the corresponding electrochemical performances as electrochemical capacitor (EC) electrodes are evaluated. It is observed that the PANI nanofiber sample prepared at water-sunflower oil interface, PANI5 possesses the lowest diameter and highest specific capacitance among all the prepared samples. Herein, we have fabricated an all-solid-state asymmetric electrochemical capacitor (AEC) of PANI5 and bio-derived chemically activated carbon (AC). The electrochemical measurements show that PANI5 and AC exhibits specific capacitance of 395 F g−1 and 240 F g−1 respectively at current density 1 A g−1. The fabricated PANI5//AC AEC exhibits areal capacitance of 70 mF cm−2 at current density of 1 mA cm−2. The energy density (Ed) and power density (Pd) of constructed AEC are found to be 19 µW h cm−2 and 696 µW cm−2, respectively. It gives the cyclic stability of 62 % retention of initial areal capacitance after completing 5000 galvanostatic charge-discharge cycles.

Designing the redox activity of CuMoO4 electrodes on N-rich reduced graphene oxide nanocomposite for high performance supercapacitor

In this investigation, environmentally friendly supercapacitor electrode materials of CuMoO4 coated on nitrogen-doped reduced graphene oxide (CMO/NRGO) nanocomposite were fabricated using a low-cost hydrothermal method. This supercapacitor has currently attracted devices and long-time stability. The electrochemical behavior of the system was investigated with working electrodes coated on Ni foam substrate in a 6 M KOH electrolyte. The findings revealed substantial advancements in specific capacitance for the fabricated electrode, attaining a value of 629.6 F g−1 at 1 A g−1. An asymmetric capacitor was fabricated by using CMO/NRGO (CuMoO4/N doped rGO) and activated carbon (AC). It design enables the hybrid capacitor to attain a balance between EDLC and PC characteristics, making it suitable for applications requiring both efficient energy storage and rapid charge/discharge capabilities. In 1.4 voltage range, an asymmetric capacitor shows good energy and power (42.85 Wh kg−1 at 580.36 W kg−1) density. After 6000 cycles, it retains 87.2 % of capacitance value. The obtained results suggest that CMO/NRGO electrode exhibits significant for developing the effective and long-lasting energy storage systems.

Enhanced supercapacitor performance through synergistic electrode design: Reduced graphene oxide-polythiophene (rGO-PTs) nanocomposite

In this investigation, we introduce an innovative method for the fabrication of a 2D/2D nanocomposite, involving the in-situ functionalization of graphene oxide (GO) with thiophene monomer. This approach employs a modified surfactant-based bi-solvent swollen liquid crystalline lamellar mesophase (SLCLM) nanoreactor system, utilizing dimethyl sulfoxide and water as primary solvents. The nanocomposite is formed via simultaneous reactions at both the edge and basal plane of GO with thiophene monomers, resulting in polymerization and reduction to generate graphene oxide-polythiophene (rGO-PTs) nanocomposite.We assess the pseudocapacitive properties of rGO-PTs in a 2 M HCl electrolyte. The cyclic voltammetry (CV) investigations reveal distinctive redox curves, indicative of the materials capacitive behaviour. In the galvanostatic charge–discharge (GCD) study, the rGO-PTs exhibits a discharge duration of 169.50 s within a potential window of −0.2 to 1 V at a current density of 7.5 A/g. This performance corresponds to a significantly higher specific capacitance of 1412 F/g, sustained over 10000 cycles as asymmetric capacitor. Notably, the rGO-PTs nanocomposite retains 106 % of its initial capacitance even after a number cycles, tested at a scan rate of 50 mV/s. The exceptional durability and electrochemical performance of the rGO-PTs nanocomposite position it as a promising alternative to conventional materials such as metals, metal oxides, pure carbonaceous substances, and polymers. The simplicity of the synthesis process, coupled with the nanocomposites outstanding electrochemical characteristics, underscores rGO-PTs potential for advancing in the field of energy storage and supercapacitor technology.

Hierarchical core-shell electrode with rGO wrapped NiWO4 nanowire arrays on Ni foam for high-performance asymmetric supercapacitors

This paper presents a novel class of hierarchical core-shell nanowire arrays (NWAs) that may greatly enhance the electrochemical storage of energy capabilities of supercapacitors. These NWAs consist of rGO sheets surrounding a NiWO4 nanowire core. The average surface area of NiWO4 nanoparticles was 105.7 m2/g, and their sizes ranged from 20 to 100 nm. The NWO/rGO composite has an impressive specific capacitance of up to 1156 F g−1 at 1 A g−1 current density. The synergistic impact of NiWO4 and rGO, which offer conducting channels and active sites, is responsible for the NWO/rGO electrode's significantly improved capacitive performance. This hybrid electrode has a lot of promise for use in energy storage devices since the cyclic stability tests showed that its starting values did not decline after 5000 cycles. In a three-electrode system, the NiWO4/rGO electrode provides more energy density compared to the NiWO4 electrode because to a boost in specific capacitance and a wider potential window (1 V for nanocomposite NiWO4/rGO vs. 0.6 V for NiWO4). Electrodes made of a nanocomposite of NiWO4 and rGO are used to construct a symmetric capacitor. Both the asymmetric and symmetric capacitors function similarly when driven within a 1.5 V potential region. On top of that, the device achieved a power density of 932 W kg−1 and an energy density of 42 Wh kg−1.

1T/2H Mixed-phase MoS2 with enlarged interlayer spacing induced via bacteria-derived carbon for long-lifespan pseudocapacitors

Pseudocapacitors (PCs) are considered prospective candidates for large-scale aqueous energy storage systems due to their high power density. However, the poor cycling stability resulting from sluggish metal ion transport kinetics and the instability of the electrode structure hinders their further applications. To address this issue, an effective strategy of 1T/2H mixed-phase MoS2 directly grown on the electrochemically activated carbon (EC) induced via bacteria-derived carbon (BC) from bacillus subtilis is proposed to achieve efficient anodes for potassium ion capacitors. The inherent nitrogen elements found in the bacteria-derived carbon, along with a trace amount of amines and their derivatives generated from amino acid decarboxylation, act as support by inserting into the MoS2 interlayer. Amines and their derivatives as intercalators could suppress the MoS2 layer stacking and mitigate structure damage, which is responsible for preventing rapid capacity fading. Thus, the mixed-phase MoS2 with an expanded interlayer spacing of 0.94 nm achieves a remarkable durability with a capacitance retention of 110.2 % after 40,000 cycles at 10 A g−1. Density Functional Theory (DFT) reveals that the mixed-phase MoS2 could improve electron transfer ability and cyclic stability, in which the rich vacancies introduced by bacteria-derived carbon could enhance the K+ adsorption. To highlight, the asymmetric capacitor device (ASC) adopting mixed-phase MoS2 anode shows a long lifespan (88 % capacitance retention over 10,000 cycles). This work will provide a green approach to boost cycling performance of MoS2 anodes and shed light on developing high-performance MoS2-based materials for electrochemical energy storage.

Study of Nd-NiMoO4 Nanocomposites Prepared by Sol–Gel Method and Their Capacitive Properties

In this paper, NiMoO4 electrode materials doped with different concentrations of Nd rare earth metals were prepared by sol–gel method. Its morphology, structure, and spectral analysis were characterized by different scanning instruments, and the experimental results show that the NiMoO4 electrode material after adding 0.5% Nd doping showed excellent capacitance performance, with a specific capacity of 2182 F/g at a current density of 1 A/g. The capacitance retention was still 98.5% after 10,000 cycles at a current density of 5 A/g, which has a better electrochemical performance compared with the NiMoO4 material with superior electrochemical performance. In addition, an asymmetric capacitor device was prepared using 0.5% Nd-NiMoO4 material and CNTs as positive and negative electrodes, respectively, and the device showed a high energy density of 73.5 Wh/kg. In addition, the capacitor device still had a capacitance retention of 91.9% after 10,000 cycles. This paper provides an effective reference route for the preparation of rare-earth-doped bimetallic oxide electrode materials.

Mathematical Modeling and Certifying for Biefeld–Brown Effect with BP Neural Network

In the force calculation of the Biefeld–Brown Effect, it is not feasible to precisely determine the magnitude of the lift force generated by an asymmetric capacitor in a scenario where its shape is arbitrary. In this paper, first, we deduce a universally applicable formula, it solves the problem of the lift force with uneven charge distribution. Second, by the experimental method of dimensional analysis based on the principle of similarity, we calculate the lift forces of all types of asymmetric capacitors. Finally, we obtain a set of thrust data through experiments, and then fit the set of experimental data through the derived mathematical model and BP neural network, respectively. It confirms the accuracy of the mathematical model.

In‐Situ Colloidal Synthetic Route to Monodispersed NiCo2S4 Nanoparticles over Nickel Foam for High‐Performance Supercapacitive Charge Storage

AbstractOne‐step colloidal synthetic route was adopted to in‐situ grow monodispersed NiCo2S4 nanoparticles (NPs) on nickel foam (NF) from metallic salts with benzyl disulfide in the media of oleylamine and octadecene. Owing to the favorable dispersion and considerable redox activity of NiCo2S4 along with tight and binder‐free connection with NF, the obtained battery‐type supercapacitor delivered a specific capacitance of 1790.8 F g−1 at 1 A g−1 via a three‐electrode system. Simultaneously, it just degraded 40 % at 20 A g−1 and maintained 86.8 % of initial specific capacitance (C0) after 2000 cyclic trials at 10 A g−1. When the NiCo2S4 NPs were assembled with active carbon (AC) forming an asymmetric capacitor device of NiCo2S4 NPs//AC, it delivered an energy density (E) of 48.7 W h kg−1 at a power density (P) of 161.1 W kg−1, and kept 21.9 W h kg−1 at a high P of 8.05 kW kg−1. Meanwhile, the capacitor manifested preeminent cycling life (C=94.5 % C0 after 5000 cyclic trials) at 5 A g−1. The in‐situ grown NiCo2S4 NPs on NF without any binder exhibited high performance in energy storage, providing a feasible way to improve the electrochemical performance of the electrode materials.

Perovskite oxide-based nanoparticles embedded MXene composites for supercapacitors and oxygen evolution reactions

In this report, perovskite oxide-MnFeO3 nanoparticles embedded MXene sheets were prepared by hydrothermal approach for the effective water splitting and energy stowage uses. The prepared MXene@MnFeO3 hybrid nanocomposites exhibited outstanding 1077 F/g specific capacitance at a current density of 1 A g−1 and excellent cycling solidity (capacitance retention after the 3000 cycle is 96.5 %). In addition, an asymmetric capacitor delivered a ultimate specific energy of 114 Wh/kg at a specific power of 2117 W/kg. MXene@MnFeO3 hybrid catalyst required a credible overpotential of 235 mV to achieve the 10 mA cm−2 current density, along with the small Tafel slope of 41 mV dec−1 for OER in 1 M KOH and long-span 24 h stability. Our proposed strategy of perovskite oxide nanoparticles hybridized highly conductive MXene sheets would be suitable alternative as the potential electrode materials for the efficient energy storage/conversion application.

Micron-sized CuO spheres anchored on three-dimensional nickel foams for high-performance aqueous asymmetric capacitor

Despite its high theoretical specific capacitance and low cost, copper oxide still suffers from insufficient utilization of active sites and poor cyclic stability when applied in asymmetric capacitors. In this work, micron-sized CuO electrode has been successfully obtained using nickel foam as substrate through an electrodeposition method. By optimizing the electrodeposition potential and designing structure, the CuO microsphere electrode delivers a high specific capacitance of 985 F g−1 at 1 A g−1. Furthermore, the asymmetric capacitor assembled with CuO electrode and activated carbon electrode exhibits a maximum energy density of 44.5 Wh kg−1 at 1600 W kg−1 and a long lifespan of 93.4% capacitance retention after 10000 cycles at 5 A g−1. These results demonstrate that the microsphere structure contributes to maintaining excellent structural stability during long cycles and then facilitate their electrochemical kinetics and capacitive performances. This work presents a novel strategy for designing and enhancing micron-sized positive electrodes for high-performance asymmetric capacitors.

Unveiling the influential factors and inhibition strategies of the electrodeposition behavior on the negative electrode in aqueous nickle‑carbon supercapacitors

It has been generally accepted that the negative electrode of aqueous nickel‑carbon asymmetric capacitors underwent capacitive reactions. However, through further research, we have unveiled an additional electrochemical reaction occurring on the negative electrode. Nickel ions were reduced to nickle and deposited on the surface of the negative electrode, which subsequently transformed to nickel oxides. This previously unrecognized phenomenon significantly impacted the energy density and cycle life of nickel‑carbon supercapacitors. The introduction of anion exchange membranes between the positive and negative electrodes was demonstrated as an effective solution in inhibiting the uncontrolled diffusion of nickel ions onto the surface of the negative electrodes. This modification led to a remarkable increase in capacity retention rate of the alkaline nickel‑carbon supercapacitor, rising from 70.45 % to 97.76 % after 10,000 cycles. Furthermore, the modified supercapacitor continued to operate reliably for over 45,000 cycles, extending the cycle life by nearly fivefold. The suppression of nickel deposition on the negative electrode represented a critical advancement in enhancing the performance and lifespan of nickel‑carbon supercapacitors.

Beyond the Rocket: A Review of Propellantless Propulsion Technologies and Concepts

For decades, the dream of unfettered space travel, free from the constraints of traditional chemical rockets, has captivated humanity's imagination. The realization of an interstellar faring civilization hinges on breakthroughs in space propulsion that transcend the limitations imposed by current chemical rocket technology. Scientists explore the intriguing realm of propellantless propulsion, a futuristic vision for space exploration that transcends the limitations of conventional propulsion. The article explores the historical roots of this field, including controversial concepts like the EmDrive and the Biefeld-Brown effect. It further examines theoretical frameworks encompassing asymmetric electrostatic pressure generation and even spacetime warping. However, the quest for reactionless motion faces a fundamental hurdle – the law of conservation of momentum. Efforts to circumvent this law involve manipulating the enigmatic quantum vacuum or creating asymmetric thrust generation within the spacecraft itself. While challenges like precise microthrust measurement, immense energy demands and material limitations persist, the potential rewards are truly transformative. Interplanetary voyages completed in significantly shorter timeframes and drastically reduced launch costs could be attained. Propellantless drives hold the potential to overcome numerous obstacles that current chemical propulsion cannot. This article underscores the critical need for continued exploration through rigorous experimental verification, the development of robust theoretical frameworks and collaborative efforts between physicists, engineers and materials scientists. This continued exploration necessitates the exploitation of existing high-efficiency solar collection technologies. Furthermore, investigations into innovative approaches, such as those utilizing metamaterials, could be pivotal in unlocking the transformative potential of propellantless propulsion systems.

The emerging chemistry of self-electrified water interfaces.

Water is known for dissipating electrostatic charges, but it is also a universal agent of matter electrification, creating charged domains in any material contacting or containing it. This new role of water was discovered during the current century. It is proven in a fast-growing number of publications reporting direct experimental measurements of excess charge and electric potential. It is indirectly verified by its success in explaining surprising phenomena in chemical synthesis, electric power generation, metastability, and phase transition kinetics. Additionally, electrification by water is opening the way for developing green technologies that are fully compatible with the environment and have great potential to contribute to sustainability. Electrification by water shows that polyphasic matter is a charge mosaic, converging with the Maxwell-Wagner-Sillars effect, which was discovered one century ago but is still often ignored. Electrified sites in a real system are niches showing various local electrochemical potentials for the charged species. Thus, the electrified mosaics display variable chemical reactivity and mass transfer patterns. Water contributes to interfacial electrification from its singular structural, electric, mixing, adsorption, and absorption properties. A long list of previously unexpected consequences of interfacial electrification includes: "on-water" reactions of chemicals dispersed in water that defy current chemical wisdom; reactions in electrified water microdroplets that do not occur in bulk water, transforming the droplets in microreactors; and lowered surface tension of water, modifying wetting, spreading, adhesion, cohesion, and other properties of matter. Asymmetric capacitors charged by moisture and water are now promising alternative equipment for simultaneously producing electric power and green hydrogen, requiring only ambient thermal energy. Changing surface tension by interfacial electrification also modifies phase-change kinetics, eliminating metastability that is the root of catastrophic electric discharges and destructive explosions. It also changes crystal habits, producing needles and dendrites that shorten battery life. These recent findings derive from a single factor, water's ability to electrify matter, touching on the most relevant aspects of chemistry. They create tremendous scientific opportunities to understand the matter better, and a new chemistry based on electrified interfaces is now emerging.

Synthesis of urchin-like NiCo2S4 electrode materials based on a two-step hydrothermal method for high-capacitance supercapacitors.

Transition metal sulfides have been considered as promising electrode materials for future super-capacitors due to their spinel structures and environmentally friendly properties. Among these materials, NiCo2S4 compounds exhibit high theoretical specific capacity but poor cycling performance. To address this issue, we synthesize several NiCo2S4 urchin balls. The NCS-1.5 nanospheres demonstrate a specific capacitance of 1352.2 F g-1 at a current density of 1 A g-1, and maintain high specific capacity after 10 000 charge-discharge cycles. An asymmetric capacitor assembled with the NCS-1.5 sample as the cathode and activated carbon as the anode achieve an energy density of 45.5 W h kg-1 at 2025 W kg-1. The urchin-like nanospheres also facilitate the combination with other materials, providing potential insights for the synthesis of supercapacitor electrode materials.

Self-supported heterojunction nanofibrous membranes for high-performance flexible asymmetric capacitors

Rational design of an electrode material with high flexibility and electrochemical performance is the key to wearable energy storage devices. Herein, a facile and productive needleless electrospinning method was introduced to prepare self-supported and flexible nanofibrous electrode materials for asymmetric capacitor. The MnO2 nanoclusters and ZIF67-derived Co3O4 nano-sheets were sequentially deposited on the surface of N, B-doped carbon nanofibers (hetero-junction MnO2/Co3O4/NB-PCNF). Attributing to the constructed multi-pathway for redox reactions on electrode, the specific capacitance of NB-PCNF and MnO2/Co3O4/NB-PCNF can reach up to 204.2F/g and 141.43F/g at a small current density of 0.1 A/g, respectively. In long-term cycling tests, the electrode materials exhibited excellent cycling stability and good rate capability. The electrodes were assembled with Potassium-ion hydrogel electrolyte to form a flexible asymmetric solid-state supercapacitor (FASS-SC). FASS-SC can reach a voltage window of 1.6 V. It provided 28.2 W h/kg at an energy density of 600 W/kg and a specific capacitance retention of 94.18 % after 10,000 cycles. The FASS-SC offers new research ideas for future flexible devices and wearable technologies.

Facile synthesis of N-doped NiCo-LDH nanowire with rich oxygen vacancies by nonthermal plasma for high-performance asymmetric capacitor electrode

Layered double hydroxides (LDHs) have been served as potential pseudo-capacitive materials, especially for high-performance supercapacitors. However, the characteristics like limited capacitance, poor conductivity, and stability of LDHs severely confine their extensive applications for future energy-storage devices. It is urgent to seek a new and simple method to modify LDH materials, to improve its electrochemical performance and apply it to supercapacitors. Herein, a facile in-situ non-thermal plasma (NTP) treatment is conducted to modify NiCo-LDH nanowires for better electrochemical performance, resulting from the introduction of N-doping and oxygen vacancies by N2 NTP. All these instructive synergies provide the optimum electrode (P-NiCoNW/CC-150) after the NTP treatment under the power of 150 W with outstanding capacitance performance of 4320 mF/cm2 at 2 mA/cm2, and superior cycling stability along with capacitance retention of 117.3 %. Most importantly, an asymmetric supercapacitor device is assembled, employing P-NiCoNW/CC-150 and oxidized carbon cloth as cathode and anode electrodes respectively, exhibiting a particularly high energy density of 364 μWh/cm2 when the power density is 4505 μW/cm2. This work confirms a feasible and green NTP method to synthesize high-performance electrodes for practical applications in future energy-storage devices but not limited to supercapacitors.

Facile synthesis of free-binder (NiCo)x(CuZn)1-xMoO4 (x = 0, 0.25, 0.5, 0.75, and 1)/nickel foam electrodes for supercapacitor application

In this work, free-binder (NiCo)x(CuZn)1-xMoO4 (x = 0, 0.25, 0.5, 0.75, and 1)/nickel foam electrodes were prepared by cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal synthesis method. The composition modulated the morphology of material deposited on the nickel foam due to the different interactions between various cations and MoO42− species. With the increase of the Ni and Co contents, the morphology of molybdates transformed from agglomerated spherical particles to the flower-like hierarchal 2D flakes. Therefore, the application of multicomponent can be improved the electrochemical performance via tuning the morphology and physicochemical properties. The (NiCo)0.5(CuZn)0.5MoO4/nickel foam electrode with flower-like morphology showed the highest specific capacitance of 1176 F g−1 at a current density of 1 A g−1 and significant rate capability of 83 % (980 F g−1 up to 5 A g−1). The hierarchal flower-like (NiCo)0.5(CuZn)0.5MoO4//activated carbon asymmetric capacitor offered the rather high performance for electrochemical energy storage including energy density of 41.5 Wh kg−1 at power density of 1450 W kg−1.