Facile synthesis and characterization of conducting polymer-metal oxide based core-shell PANI-Pr2O–NiO–Co3O4 nanocomposite: As electrode material for supercapacitor

Metal oxide nanoparticles and their composites with conducting polymers, specifically Polyaniline (PANI) were utilized for fabricating nanoscale supercapacitor (SC) electrode materials. In the present study, we have synthesized pristine Pr₂O₃, NiO, Co₃O₄ nanoparticles, binary PANI-Pr₂O₃, PANI-NiO, PANI-Co₃O₄, ternary Pr₂O₃–NiO–Co₃O₄, and quaternary PANI-Pr₂O₃–NiO–Co₃O₄ spherical core-shell nanocomposite using co-precipitation and ultra-sonication methods. The grown samples were characterized with different analytical techniques. The XRD pattern revealed that the as-synthesized products were crystalline with Pr₂O₃ hexagonal phase, NiO cubic phase, and Co₃O₄ cubic phase in pure and nanocomposites. The Williamson-Hall, Scherrer, and size-strain plot methods were employed to study the crystalline development and contribution of micro-strain. FTIR pattern exhibited the metal-oxygen and PANI bond vibrations. FE-SEM images shown the spherical core-shell shape morphology of quaternary nanocomposite. EDX evident the presence of praseodymium, cobalt, and nickel in synthesized samples. UV–vis spectroscopy confirmed the absorption in the visible region. The IV graphs showed a higher conductivity of quaternary nanocomposite. The cyclic voltammetry results revealed that the quaternary nanocomposite has a higher specific capacitance 500 Fg^-1 as compared to binary nanocomposites 134 F g^?1 (PANI-Pr₂O₃), 143 F g^?1 (PANI-Co₃O₄), 256 F g^?1 (PANI-NiO), and PANI (90.8 F g^?1) at a scan rate of 5 m Vs^?1. The GCD results also showed that the quaternary nanocomposite has a higher specific capacitance of 905 F g^?1 at current density 1 A g^?1 with maximum energy density and power density of 87.99 kWhkg^-1 and 2.6 k W kg^?1_, respectively. The EIS curve also confirmed that the quaternary nanocomposite has a lower polarization resistance (R_p) and solution resistance (R_s). The higher capacitance of quaternary nanocomposite can facilitate ion transfer, and the formation of its core-shell structure flourish to enhance surface-dependent electrochemical properties. Furthermore, this study gives a novel research idea to manufacture electrode materials for supercapacitors.     

Template-free synthesis of novel Co3O4 micro-bundles assembled with flakes for high-performance hybrid supercapacitors

In this paper, a novel Co₃O₄ micro-bundles structure (Co₃O₄ MBs) was obtained at 120 °C after a hydrothermal reaction for 24 h and followed by an annealing treatment at 300 °C in air. The unique Co₃O₄ MBs are constructed by many adjacent flakes with 0.4 μm in thickness, and exhibit a large surface area of 81.2 m² g^?1 and a mean pore diameter of 6.14 nm, which may facilitate a sufficient contact with electrolyte and then shorten the diffusion pathway of ions. A remarkable electrochemical behavior including specific capacity of 282.3 C g^?1 at 1 A g^?1 and 205.9 C g^?1 at 10 A g^?1, and an excellent cycling performance with 74.6% capacity retention after 4000 charge-discharge process at 5 A g^?1 are achieved when the test of Co₃O₄ MBs-modified electrode is performed using three-electrode configuration. Additionally, a hybrid supercapacitor (HSC) was fabricated with the obtained Co₃O₄ MBs as positive electrode and commercial activated carbon (AC) as negative electrode. The HSC exhibits a specific capacity of 144.1 C g^?1 at 1 A g^?1 and 126.4% capacity retention after 5000 cycles at 5 A g^?1. An energy density of 38.5 W h kg^?1 can be obtained at a power density of 962.0 W kg^?1, and 29.5 W h kg^?1 is still retained at 8532.5 W kg^?1. The simple synthetic strategy can be applicable to the synthesis of other transition metal oxides with superior electrochemical performance.     

Highly porous metal organic framework derived NiO hollow spheres and flowers for oxygen evolution reaction and supercapacitors

In this study, metal-organic-framework (MOF) derived porous NiO hollow spheres and flowers were obtained using facile solvothermal synthesis and heat treatment. After pyrolyzing, the flower like and hollow spherical like morphology of NiO nanoparticles was successfully inherited from the initial MOF-based templates. The electrochemical studies demonstrated that the porous NiO hallow spheres unveiled a better supercapacitive performance (specific capacitance (C_s) = 1058 F g^?1 at current density (j) = 2 A g^?1) and oxygen evolution reaction (OER) catalytic activity (overpotential (?) = 323 mV) compared to porous NiO flowers (C_s = 857 F g^?1 at j = 2 A g^?1 and ? = 346 mV). Moreover, excellent capacity retention of over 93% was obtained in porous NiO-hs nanoparticles even after 5000 cycles. The fabricated NiO//Fe₂O₃ asymmetric supercapacitor delivered an energy density (E) of 35.75 W h Kg^?1 under power density (P) of 780 W kg^?1 and showed promising stability over 3000 cycles. Considering the ease of preparation and high catalytic activity and supercapacitive performance, these prous NiO hallow structures can be considered as a potential electrode material for next generation energy storage devices and OER catalysts.     

Solution combustion synthesis of crystalline V2O3 and amorphous V2O3/C as anode for lithium-ion battery

In this paper, crystalline V₂O₃ and amorphous V₂O₃/C products are synthesized via one-pot solution combustion synthesis (SCS) method (completed within 2 minutes). The characteristics of combustion products could be tuned by changing the amounts of glucose. The as-synthesized crystalline V₂O₃ nanopowder consists of nanoparticles with average size of ~100 nm. Amorphous V₂O₃/C composite exhibits large porous microsheet structure in which oxygen vacancy-enabled amorphous V₂O₃ particles are embedded into N-doped carbon microsheets. The existence of oxygen vacancies can promote energetics for the transport of electrons and ions and maintain the integrity of sample surface morphology. Moreover, N-doping can enhance electrical conductivity and promote the diffusion of electrons and lithium ions. Amorphous V₂O₃/C composite possesses high reversible capacity and superior cycling stability (833 mAh g⁻¹ at 1 A g⁻¹ after 250 cycles, 867 mAh g⁻¹ at 0.1 A g⁻¹ after 100 cycles), indicating its potential as excellent anode material for lithium-ion battery. The proposed one-step, time- and energy-efficient SCS method has the potential to prepare other oxygen vacancy-enabled transition metal oxides for energy storage.     

A new As3Mo8V4/PANi/rGO composite for high performance supercapacitor electrode

Herein, [As₂^IIIAs^VMo₈^VIV₄^IVO₄₀]₂[Cu^ICu₂^II(pz)₄]₂·9H₂O/polyaniline/reduced graphene oxide (pz = pyrazine, abbreviated to As₃Mo₈V₄/PANi/rGO) composite is first assembled, characterized and systematically explored for its supercapacitor performance. As₃Mo₈V₄/PANi/rGO composite shows a exceptional specific capacitance (2351 F g^?1 at 1 A g^?1) and outstanding cyclic stability (96.9% after 5000 cycles). The symmetric supercapacitor exhibits high specific capacitance of 1295 F g^?1 at 1 A g^?1 and excellent energy density of 88.1 Wh kg^-1 at power density of 349.6 W kg^-1, while maintaining a notable capacitance retention of 85.7% after 5000 cycles at 2 A g^-1. The above results confirm the potential application of As₃Mo₈V₄/PANi/rGO composite in energy storage devices.     

Anchoring mesoporous Fe3O4 nanospheres onto N-doped carbon nanotubes toward high-performance composite electrodes for supercapacitors

Fe-based oxide electrodes for practical applications in supercapacitors (SCs) suffer from low conductivity and poor structural stability. To settle these issues, we report on the design and synthesis of Fe₃O₄/carbon nanocomposites via firmly anchoring mesoporous Fe₃O₄ nanospheres onto N-doped carbon nanotubes (N-CNTs) via C–O–Fe bonds. Mesoporous Fe₃O₄ nanospheres are featured by rich electroactive sites and short ion diffusion pathways. The N-CNTs, on the other hand, serve as the scaffolds, which not only provide conductive networks but also suppress the accumulation between mesoporous Fe₃O₄ nanospheres as well as alleviate volume changes during charge/discharge cycles. Accordingly, the constructed Fe₃O₄/N-CNTs nanocomposite electrode demonstrates improved specific capacity values of up to 314 C g⁻¹ at 1 A g⁻¹, with 92% retention of the initial capacity after 5000 cycles at 10 A g⁻¹. In addition, the assembled Fe₃O₄/N-CNTs//active carbon (AC) asymmetric supercapacitor (ASC) device possesses an energy density of 25.3 Wh kg⁻¹, suggesting that the prepared Fe₃O₄/N-CNTs nanocomposites are promising electrode materials for use in SCs.     

Constructing three-dimensional Li-transport channels within the Fe3O4@SiO2@RGO composite to improve its electrochemical performance in Li-ion batteries

Magnetite Fe₃O₄ particles are usually pulverized when used as the anode material for Li-ion batteries and thus the solid electrolyte interface film grows on the surface progressively, leading to inferior cycling performance and poor rate capability. To solve these issues, core-shell Fe₃O₄@SiO₂ particles are wrapped by reduced graphene oxide (RGO), and meso-/micro-pores are produced not only in the SiO₂ layers but also in the RGO nanosheets by chemical etching, forming three-dimensional (3D) continuous channels for Li⁺ transportation. Benefiting from this unique structure, the as-prepared Fe₃O₄@mSiO₂@RGO composite can deliver a capacity of 1630 mA h g⁻¹ at 0.1 A g⁻¹ over the potential range of 0.01–3.00 V (vs. Li⁺/Li) in the first discharge along with an initial coulombic efficiency of 86%, and can retain the capacity of 514 mA h g⁻¹ at 5 A g⁻¹ after 1000 cycles, exhibiting an outstanding rate capability and a long-term span life. The results indicate that pseudocapacitive behavior enables this composite to charge/discharge fast while the porous SiO₂ shell and RGO nanosheets effectively accommodate the volume change of the Fe₃O₄ particles during cycling. Our findings provide a feasible strategy for improving the electrochemical properties of the Fe₃O₄ anode in Li-ion batteries.     

SnO2 QDs-decorated V2O5 nanobelts for photoelectrochemical water splitting under visible light

Highly efficient and solvent-free SnO₂ quantum dots (QDs)-decorated V₂O₅ nanobelt catalysts were synthesized to control environmental pollution via photoelectrochemical water splitting. To confirm the formation of the nanostructures, several analyses were performed. The modification with SnO₂ QDs demonstrated a significant influence on the optical properties of the V₂O₅ nanobelts. The optical bandgap of the synthesized V₂O₅ nanobelt-based catalysts varied between 2.19 and 2.50 eV. The Sn⁴⁺ and V⁵⁺ chemical states of the pure SnO₂ QDs and V₂O₅ nanobelts, respectively, were determined using X-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy revealed that the optimized SnO₂ QDs-decorated V₂O₅ nanobelts had the lowest charge transfer resistance along with capacitive behavior in 0.1 M NaOH electrolyte. The concentration of the SnO₂ QDs had a significant effect on the photocurrent densities of the V₂O₅ nanobelts. A maximum photocurrent density of 1.161 mAcm^?2 was obtained for the sample with 80 mg V₂O₅ nanobelts decorated with 20 mg SnO₂ QDs. This occurred because of the significant enhancement in the light absorption, improved contact at the photoelectrode-electrolyte interface, reduced ion-conduction path resistance, and lower charge transfer resistance of the synthesized photoelectrode.     

MWCNTs-GONRs/Co3O4 electrode with needle-like arrays for outstanding supercapacitors

Multiwalled carbon nanotubes-graphene oxide nanoribbons (MWCNTs-GONRs) exhibit high specific surface area and good electroconductivity because of their unique three-dimensional cross-linking structure with the properties of both CNTs and GONRs. In this study, a hydrothermal method was employed to anchor MWCNTs–GONRs onto a Ni foam (NF) to obtain a precursor substrate. Subsequently, Co₃O₄ arrays were grown on the NF substrate to synthesize a MWCNTs–GONR/Co₃O₄ electrode. The electrode showed a capacitance of 846.2 F g⁻¹ at 1 A g⁻¹ and a capacitance retention of 90.1% after 3000 cycles. Furthermore, MWCNTs–GONRs/Co₃O₄ and active carbon (AC) were used as the positive and negative electrodes, respectively, to assemble a supercapacitor, which delivered a maximum energy density of 38.23 W h kg⁻¹ and a high power density of 6.80 kW kg⁻¹. In addition, the specific capacitance of the device reached a maximum of 91.5% after 9000 cycles. Thus, the MWCNTs–GONRs/Co₃O₄ electrode showed huge potential for supercapacitor applications.     

High-temperature ultrafast welding creating favorable V2O5 and conductive agents interface for high specific energy thermal batteries

The high interfacial resistance between V₂O₅ cathode materials and conductive agents (molten salt and super carbon) is one of the biggest issues that hinder the development of high specific energy thermal batteries. Designing fast Li⁺ and e^– transport channels in cathode electrodes is considered as an effect method to improve electrochemical performance. Hence, a high-temperature ultrafast welding is proposed to reduce V₂O₅/conductive agents interfacial resistance by reconstructing the transmission channels of Li⁺ and e^– in this paper. The experimental studies reveal the optimum ultrafast welding of 700 °C for 10 s, eliminating gap resistance of cathode electrodes induced by the melt of solid molten salt and rebuilding the more plentiful Li⁺ and e^– transport channels, further reducing the contact resistance and gap resistance. Therefore, the electrodes deliver a high specific capacity of 270.69 mAh g^?1 and a high specific energy of 610.60 Wh kg^?1 at 0.1 A cm^?2 and 500 °C with a cut-off voltage of 1.6 V. The high-temperature ultrafast welding provides guidance to build Li⁺ and e^– transport channels of other cathode materials in thermal batteries.     

Self-doped 2D-V2O5 nanoflakes – A high electrochemical performance cathode in rechargeable zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) are highly promising energy storage systems owing to their high energy and power density, along with their inherent safety in large-scale energy storage. The well-known low-cost potential cathode materials, such as vanadium oxides (e.g., V₂O₅), exhibit lower cycling performance, particularly at higher current densities because of dissolution in the electrolyte and lower electrical conductivity. We synthesized two-dimensional (2D) V₂O₅ nanoflakes, self-doped with V⁴⁺ ions from ammonium vanadates, using an annealing process. These porous V₂O₅ nanoflakes formed by the relatively larger agglomerated V₂O₅ nanoparticles consisting of a significant amount of V⁴⁺ ions, which possess higher electrical conductivity than commercial V₂O₅. V⁴⁺-doped V₂O₅ (d-V₂O₅) were used as the cathode material in AZIBs and delivered a stable specific capacity of 430 mAh g⁻¹ (@ 0.5 A g⁻¹). Furthermore, their electrochemical performance was better than that of the undoped commercial V₂O₅ samples. At a higher current density (10 A g⁻¹), d-V₂O₅ exhibited an excellent highly reversible specific capacity of 190 mAh g⁻¹ and retained 86% of its initial capacity after 1000 cycles. This stable electrochemical performance is attributed to the enhanced electrical conductivity, higher diffusion coefficient of Zn ions, and delayed electrode solubility in the electrolyte owing to the presence of self-doped V⁴⁺ ions in V₂O₅.     

Electrophoretic co-deposition of Bi2O3–multiwalled carbon nanotubes coating as supercapacitor electrode

Nafion is suggested as an efficient assistant in preparing supercapacitor by employing nanoparticles. In this work, using a bi-additive of 0.10-mM NaOH + 0.10 g L⁻¹ Nafion, Nafion-assisted electrophoretic co-deposition of Bi₂O₃–multiwalled carbon nanotubes (MWCNTs) coating is successfully realized in ethanol solvent. The capacitance performances of the electrophoretic coatings in 6.0-M KOH electrolyte are investigated by cyclic voltammetry and galvanostatic charge–discharge techniques. Comparing with Bi₂O₃ coating prepared with electrophoretic deposition (EPD) by employing other additive (such as polyethyleneimine), the Bi₂O₃ coating prepared by Nafion-assisted EPD shows a better capacitance performance. Benefiting from the improvement in coating conductivity caused by MWCNTs, with a small additional amount of 4.0 wt.%, the Bi₂O₃–MWCNTs coating exhibits an amazing 164% increase of mass-specific capacitance (473 F g⁻¹ at the current density of 1.0 A g⁻¹) in comparison with pure Bi₂O₃ coating (179 F g⁻¹ at the current density of 1.0 A g⁻¹). The cyclic stability test exhibits excellent capacitance retention of 88.7% over 3000 cycles at a constant current density of 10.0 A g⁻¹. This work combines the advantages of MWCNTs, Nafion, and EPD to provide a facile route for preparing Bi₂O₃-based coating as a high-performance supercapacitor electrode.     

Conformal coatings of NiCo2O4 nanoparticles and nanosheets on carbon nanotubes for supercapacitor electrodes

NiCo₂O₄ is a promising electrode material for supercapacitors and it has been widely investigated. However, its low conductivity restricts the reaction kinetics. Combining it with carbon materials can efficiently overcome the issue. But, very limited research about the homogenous coatings of NiCo₂O₄ nanocrystals on carbon nanotubes (CNTs) is reported. In this work, thin nanosheets and small nanoparticles of NiCo₂O₄ densely coated on CNTs are synthesized by tuning the annealing time with a hybrid of metal hydroxide@CNTs as a precursor. In the precursor, core−shell structures are formed by conformally coating 2D metal hydroxides on CNTs. After annealing it at 300 °C for different time, NiCo₂O₄ nanosheets or nanoparticles are then obtained and the core−shell structure is remained. Due to the reduced crystal size of NiCo₂O₄ and the high conductivity of CNTs, the composites have large specific capacitances, excellent rate performances, and good stability. The composite of NiCo₂O₄ nanoparticles on CNTs has a higher specific capacitance, about 1786 F g⁻¹ at 0.5 A g⁻¹, than the hybrid of NiCo₂O₄ nanosheets on CNTs due to their different morphologies. Using the composite as positive electrode and activated carbon as negative electrode, a hybrid capacitor cell can work in a voltage of 1.6 V, delivering an energy density of 32.5 Wh kg⁻¹ at 800 W kg⁻¹, showing a large potential for supercapacitors.     

Development of bifunctional Mo doped ZnAl2O4 spinel nanorods array directly grown on carbon fiber for supercapacitor and OER application

Electrochemical energy storage and water splitting strategies may be greatly improved with proper structural design and doping techniques. In the present study, molybdenum-doped ZnAl₂O₄ loaded on carbon fiber (Mo–ZnAl₂O₄/CF) was fabricated via a simple hydrothermal synthetic approach. Due to its unique hierarchical nanostructures and enhanced electrical, structural topologies, Mo-doped ZnAl₂O₄ demonstrates exceptional supercapacitor performance and electrocatalytic oxygen evolution reaction activity. The Mo-doped ZnAl₂O₄ electrode material exhibited 1477.63 F g^?1 specific capacitance, 46.57 Wh Kg^?1 specific energy and specific power of 476.4 W kg^?1 at 1 A g^?1. After 5000 cycles, the pseudo supercapacitor retains 97.46% of its capacitance and displays stable behavior over 50 h. During the OER reaction, the Mo–ZnAl₂O₄/CF as an electrocatalyst rapidly self-reconstructs, resulting in many oxygen vacancies, and causes a lower 38 mV dec^?1 Tafel slope and overpotential potential of 255 mV to achieved 10 mA cm^?2 current flow and responsible for the excellent stability of the electrocatalyst. These findings suggest that multifunctional materials based electrode for electrical energy conversion and storage become more efficient and stable by using Mo for doping to generate porous hierarchical structures and local amorphous phases.     

Promising carbon nanosheets decorated by self-assembled MoO2 nanoparticles: Controllable synthesis,boosting performance and application in symmetric coin cell supercapacitors

A composite containing self-assembled MoO₂ nanoparticles and functional carbon nanosheets was obtained via a facile and controllable strategy. Two-dimensional functional carbon nanosheets as matrices have close contact with MoO₂ nanoparticles, which assists in the improvement of electronic conductivity, provides efficient pathways and accelerates electron transfer. The carbon nanosheets have functional groups on the surface, which could serve as the nucleation sites for MoO₂. The MC-0.12 composite shows optimal specific capacitance (190.9 F g^-1 at 1 A g^-1) and excellent cycle stability between monomers and composites with different constituents. The assembled symmetrical coin cell supercapacitor using MC-0.12 possesses the maximum energy density of 10.3 Wh kg^-1 at a power density of 378 W kg^-1 and still maintains the energy density of 7.9 Wh kg^-1 at 1682 W kg^-1 with a larger potential window. The capacitance retention (92%) of the assembled device is maintained after 2000 cycles, showing outstanding cycle life. Therefore, the integration of self-assembled MoO₂ nanoparticles with 2D functional carbon nanosheets provides the composite superior electrochemical performance for supercapacitor applications.     

Holey graphene interpenetrating networks for boosting high-capacitive Co3O4 electrodes via an electrophoretic deposition process

A composite of Co₃O₄/holey graphene (Co₃O₄/HG) was prepared via a facile hydrothermal route, and was then processed into an electrode by an electrophoretic deposition process. Holey graphene (HG) wrapped Co₃O₄ to form a 3D skeleton network, thereby providing high electrical conductivity, and the holes in HG could further shorten the electrolyte ion diffusion pathway. Therefore, by adjusting the mass ratio of Co₃O₄ to HG, the Co₃O₄/HG composite afforded an enhanced capacitance of 2714 F g⁻¹ (at a current density of 1 A g⁻¹), which is 20 times higher than that of pure Co₃O₄. To further explore the practical applications of Co₃O₄/HG, a symmetric supercapacitor employing Co₃O₄/HG was fabricated. The supercapacitor functioned stably at potentials up to 1.2 V, with an enhanced energy density of 165 Wh kg⁻¹ and a high power density of 0.6 kW kg⁻¹ at 1 A g⁻¹.     

One-step hydrothermal synthesis of hybrid core-shell Co3O4@SnO2–SnO for supercapacitor electrodes

We successfully synthesized a novel core-shell hybrid metal oxide via a simple one-step hydrothermal method without annealing. This composite of Co₃O₄ particles covered with SnO₂–SnO (Co₃O₄@SnO₂–SnO) predicted better performance compared to pure Co₃O₄, which strongly depends on the synthetic temperature. The Co₃O₄@SnO₂–SnO prepared at a temperature of 250 °C (labeled Co₃O₄@SnO₂–SnO-250) exhibited an outstanding specific capacitance of 325 F g⁻¹ under the current density of 1 A g⁻¹, which was much higher than those of Co₃O₄ (12.6 F g⁻¹) and other composites. Additionally, the sample also exhibited good cycle stability performance with a retention rate of 100% after 5000 cycles at a current density of 5 A g⁻¹. Through X-ray photoelectron spectroscopy analysis, the presumed mechanism was that Sn-O_x decreases the surface electron densities of Co₃O₄, which is beneficial to OH⁻ adsorption and specific capacitance improvement, and the synthetic temperature had a strong impact on the microstructure and thus on the surface electron densities. The most.obvious finding to emerge from this study is that the specific capacitance can be improved through adjusting the surface electron densities of transition metal oxides.     

Composites of V2O3–ordered mesoporous carbon as anode materials for lithium-ion batteries

The composites of V₂O₃–ordered mesoporous carbon (V₂O₃–OMC) were synthesized and used as anode materials for Li-ion intercalation. These materials exhibited large reversible capacity, high rate performance and excellent cycling stability. For instance, a reversible capacity of V₂O₃–OMC composites was 536 mA h g⁻¹ after 180 cycles at a current density of 0.1 A g⁻¹. The high electrochemical performance of the V₂O₃–OMC composites is attributed to the anchoring of nanoparticles on mesoporous carbon for improving the electrochemical active of V₂O₃ particles for energy storage applications in high performance lithium-ion batteries.     

Lithium insertion in ultra-thin nanobelts of Ag2V4O11/Ag

In this study, ultra-thin nanobelts of Ag₂V₄O₁₁/Ag were successfully synthesized. The synthesized ultra-thin nanobelts of Ag₂V₄O₁₁/Ag are highly crystalline and the thickness is found to be about 5 nm. A lithium battery using ultra-thin nanobelts of Ag₂V₄O₁₁/Ag as the active materials of the positive electrode exhibits a high initial discharge capacity of 276 mAh g⁻¹, corresponding to the formation of Li_xAg₂V₄O₁₁ (x = 6). With increased cycling, the electrode made of ultra-thin nanobelts of Ag₂V₄O₁₁/Ag tends to loose electrochemical activity due to Ag⁺ ions in the ultra-thin nanobelts of Ag₂V₄O₁₁ were reduced and new phase was formed.     

N/S-Dual doped MnO modified spore-based ellipsoidal porous carbons for supercapacitors

Owing to the significance and requirement of renewable energy resources, in this study, ellipsoidal porous carbons with yolk-shell structures assembled using MnO and Ganoderma lucidum spores are fabricated for application prospects in energy storage systems; they exhibit excellent ion transfer capability. However, the surface of carbon nanomaterials is naturally hydrophobic, resulting in a lower energy density. Herein, heteroatom doping and O₂/Ar plasma surface treatment are utilized to obtain high specific capacitance and fast charging. Surface functionalization increases the surface roughness and oxygen-containing functional groups of the material. The specific capacitance of the best sample MnO/GSC-O–NS–10 was 568.9 F g⁻¹ when the current density was 0.5 A g⁻¹. The performance test was carried out for 10000 cycles at a current density of 10 A g⁻¹ and the capacitance retention rate was 75.11%. The assembled two-electrode capacitor exhibited a specific capacitance of 240.4 F g⁻¹ and an energy density of 33.4 Wh kg⁻¹ at a power density of 407 W kg ⁻¹. These findings provide sufficient theoretical guidance for the development of high-performance supercapacitors.