High-performance hybrid supercapacitor based on the porous copper cobaltite/cupric oxide nanosheets as a battery-type positive electrode material

In this work, CuCo₂O₄/CuO nanosheets (NSs) and CuCo₂O₄ oblique prisms (OPs) were synthesized at 130 °C with different amounts of hexamethyltetramine (HMTA) and reaction time through a hydrothermal method, and followed by an annealing treatment of precursors in air. The CuCo₂O₄/CuO NSs with 40 nm in thickness possessed a large specific surface area of 43.34 m² g⁻¹ and a mean pore size of 18.14 nm. The electrochemical tests revealed that the CuCo₂O₄/CuO NSs were belonged to the battery-type electrode material and exhibited a specific capacity of 395.55 C g⁻¹ at the current density of 1 A g⁻¹, higher than 258.16 C g⁻¹ for CuCo₂O₄ OPs. A hybrid supercapacitor (HSC) was assembled with activated carbon (AC) as negative electrode and CuCo₂O₄-based materials as positive electrode. The CuCo₂O₄/CuO NSs//AC HSC exhibited a high energy density of 30.18 Wh kg⁻¹ at a power density of 869.62 W kg⁻¹, and showed a fantastic cycling performance with 105.22% capacity retention over 5000 cycles. In contrast, the CuCo₂O₄ OPs//AC HSC delivered an energy density 26.27 Wh kg⁻¹ at 916.74 W kg⁻¹. These impressive electrochemical properties indicate that CuCo₂O₄/CuO NSs may serve as a promising electrode material for the highly capable hybrid supercapacitors in the near future.     

Facile preparation of SnS2 nanoflowers and nanoplates for the application of high-performance hybrid supercapacitors

In this work, the SnS₂ nanoflowers (SnS₂ NFs) were solvothermally prepared in the solvent of ethanol, while SnS₂ nanoplates (SnS₂ NPs) were obtained through the identical conditions except for the solvent of water. The flowers were assembled with numerous nanosheets with very thin thickness, and the NPs exhibited hexagonal shape. When used as the battery-type electrode material for supercapacitors, the SnS₂ NFs delivered a specific capacity of as high as 264.4 C g^?1 at 1 A g^?1, which was higher than the 201.6 C g^?1 of SnS₂ NPs. Furthermore, a hybrid supercapacitor (HSC) was assembled with the SnS₂ as positive electrode and activated carbon (AC) as negative electrode, respectively. The SnS₂ NFs//AC HSC exhibited a high energy density of 28.1 Wh kg^?1 at 904.3 W kg^?1, which was higher than the 24.2 Wh kg^?1 at 844.3 W kg^?1 of SnS₂ NPs//AC HSC. Especially, when the power density was enhanced to the highest value of 8666.8 W kg^?1, the NFs-based device could still hold 20.4 Wh kg^?1. In addition, both HSC devices showed an excellent cycling stability after 5000 cycles at 5 A g^?1. The present method is simple and can be extended to the preparation of other transition metal sulfides (TMSs)-based electrode materials with brilliant electrochemical performance for supercapacitors.     

Improved energy conversion and storage performance enabled by hierarchical zigzag-like P-doped CuCo2O4 nanosheets based 3D electrode materials

Developing a bi-functional material which can meet both electrochemical water splitting and supercapacitors (SCs) is a hot spot in current research. In this study, hierarchical zigzag-like phosphorus doped CuCo₂O₄ nanosheets based 3D electrode materials were successfully synthesized via a hydrothermal method and followed by thermal treatment. Since the unique morphology of 2D nanosheets with zigzag-like edges could provide more reactive sites, which is not only conducive to the hydrogen evolution reaction (HER), but also conducive to the electrochemical energy storage. Meanwhile, the doping of phosphorus was adopted to improve the conductivity, which would further enhance the electrochemical properties of CuCo₂O₄. Thereafter, its performance for HER and SCs in 1 M KOH were systematically investigated. As an electrode for HER, it only required a low overpotential of 152 mV to reach 10 mA cm^?2 with a Tafel slope of 115.7 mV dec^?1. Furthermore, I-t test result showed an excellent stability. As an electrode for SCs, it exhibited a high specific capacity of 896.9C g^?1 at 1 A g^?1 in three-electrode system. All in all, the obtained hierarchical zigzag-like phosphorus doped CuCo₂O₄ nanosheets provided a feasible route for the design of bi-functional electrode materials both for energy conversion and storage.     

Electrospun NiO/C nanofibers as electrode materials for hybrid supercapacitors with superior electrochemical performance

In this work, the porous NiO/C nanofibers (NFs) were rationally designed and prepared by a convenient electrospinning method, and followed with a calcination conversion of the precursor in air. The NiO/C composite exhibited a net-like structure that was composed of many intertwined NFs with an average diameter of about 200 nm. The electrochemical measurements demonstrated that the porous NiO/C NFs exhibited an electrochemical feature of battery-type electrode material, and delivered a specific capacity as high as 461.26 C g^?1 under 1 A g^?1 and an excellent rate capability with 82.7% capacity retention at 10 A g^?1. A hybrid supercapacitor (NiO/C NFs//AC HSC) was assembled with NiO/C NFs as positive electrode and activated carbon (AC) as negative electrode, which delivered an energy density of 31.82 W h kg^?1 under a power density of 816.36 W kg^?1 along with an outstanding cyclic stability of 90.9% capacity retention over 5000 cycles at 5 A g^?1. This simple synthetic method can be extended to the fabrication of other transition metal oxides (TMOs)-based NFs for their further applications in high-performance electrochemical energy storage devices such as hybrid supercapacitors, batteries, and so on.     

Battery-type and binder-free MgCo2O4-NWs@NF electrode materials for the assembly of advanced hybrid supercapacitors

In this study, the hetero-structure of MgCo₂O₄ nanowires (MCO-NWs) and microcubes (MCO-MCs) on the skeleton of nickel foam (NF) was realized through a simple hydrothermal method and subsequent annealing treatment, and then served as a binder-free cathode for assembly of high-performance hybrid supercapacitor (HSC). Such synthetic methodology avoided the traditional usage of conductive and binder reagents for the electrode fabrication. The electrochemical tests indicated its battery-type characteristics, and the MCO-NWs@NF exhibited a huge specific capacity (C_s) of 389.0 C g^?1 as well as 86.2% capacity retention when the current density boosted from 1 to 10 A g^?1. The assembled HSC with activated carbon (AC) as anode further demonstrated the advantages of this electrode material. After 5000 cycles at 6 A g^?1, the MCO-NWs@NF//AC HSC showed good long-term cycling stability without any decay in capacitance, and could deliver an energy density (E_d) of 37.9 W h kg^?1 at the power density (P_d) of 958.1 W kg^?1, higher than the 30.4 W h kg^?1 of MCs-based HSC. These impressive results regarding electrochemical performance suggest that MCO-NWs@NF may be a promising candidate to serve as a battery-type material in electrochemical energy storage applications such as HSCs, batteries, and so on.     

CoFe2O4@methyl cellulose core-shell nanostructure and their hybrids with functionalized graphene aerogel for high performance asymmetric supercapacitor

Recently, the use of asymmetric supercapacitors (ASC) has attracted much attention due to their optimum storage of energy and a high range of voltage. Here, we have indicated the design and fabrication of a unique ASC based on metal-spinel core-shell nanocomposite (CoFe₂O₄@MC) as a positive electrode and a p-phenylenediamine (PPDA)-graphene aerogel composite (AP) as a negative electrode in aqueous KOH electrolyte solution. The CoFe₂O₄@MC nanocomposite was prepared by the chemical deposition method. The AP was also effortlessly organized using the hydrothermal method. Considering the incorporation of methylcellulose carbohydrate polymer (MC) into the CoFe₂O₄ nanomaterial and consequently having a porous structure, a specific capacitance of 433.3 F g^?1 was obtained at the current density of 1 A g^?1 with the configuration of three electrodes. The CoFe₂O₄@MC//AP-ASC operates in the voltage range up to 2.3 V and provides a specific capacitance of 99 in 1 A g^?1. It presents an impressive energy density and power density of ~73 W h Kg^?1 and 1056 W kg^?1, respectively which prove its quality. The most important feature seems to be good cycling stability and capacity retention of 89% after 2000 cycles. These splendid outcomes show that CoFe₂O₄@MC nanocomposite possibly seems to be a satisfying choice for the next generation of devices with the capability of energy storage.     

Synthesis of hollow carbon-incorporated NiCoM (M = Mn,Cu, Zn) layered double hydroxide nanocages for hybrid supercapacitors

Nanostructures and compositions are the most crucial aspects in the design of electrode materials with excellent properties for hybrid supercapacitors (HSCs). In this study, bimetallic CoM-zeolitic imidazolate framework-67 (CoM-ZIF-67, M = Mn, Cu, and Zn) derived nanosheet-constructed hollow carbon-incorporated NiCoM layered double hydroxide nanocages (NiCoM-LDH/C) are successfully synthesized via the thermal annealing and subsequent etching/ion-exchange reaction. As a consequence, the NiCoM-LDH/C materials exhibit significantly improved electrochemical performance. Specifically, the optimized NiCoMn-LDH/C electrode possesses an excellent capacity performance of 888.3 C g^?1 at 1 A g^?1. Moreover, the HSC device assembled by NiCoMn-LDH/C and active carbon delivers a remarkable energy density of 46.5 Wh kg^?1 at a power density of 792.5 W kg^?1 and possesses superior cyclic stability with about 92.05% capacity retention after 5000 cycles. This work may offer a feasible and effective approach for the synthesis of carbon-incorporated ternary layered double hydroxide nanocage materials for high-performance HSC applications.     

Multifunctional Co3O4/Ti3C2Tx MXene nanocomposites for integrated all solid-state asymmetric supercapacitors and energy-saving electrochemical systems of H2 production by urea and alcohols electrolysis

Co₃O₄/Ti₃C₂T_x MXene nanocomposites have been fabricated by vacuum filtration and hydrothermal-annealing methods, and their electrochemical performance were investigated for energy storage and conversion, systematically. As electrode materials, Co₃O₄/Ti₃C₂T_x MXene nanocomposites in 6 M KOH solution demonstrated the specific capacitance of 240.1 F g^?1 at 0.1 A g^?1 and the long-term cycle stability. The solid-state asymmetric supercapacitors exhibited an operating potential window of 1.4 V, a specific capacitance of 97.9 F g^?1at 0.25 A g^?1, an energy density of 95.9 Wh kg^?1 at a power density of 630.4 W kg^?1, and excellent long-term durability. Furthermore, the connected solid-state asymmetric supercapacitors inseries and parallels presented the promising practical applications. Besides, Co₃O₄/Ti₃C₂T_x nanocomposites displayed outstanding catalytic behaviors for energy-saving H₂ generation by urea and alcohols electrolysis. The electrolyzer in KOH + CH₃CH₂OH electrolyte required only 1.33 V potential to deliver the current density of 0.5 A g^?1. Especially, the elctrochemical system of H₂ production by The electrolyzer and the powered solid-state asymmetric supercapacitors based on Co₃O₄/Ti₃C₂T_x nanocomposites was constructed, demonstrating outstanding properties of H₂ production. Therefore, this study not only shows enormous potential of Co₃O₄/Ti₃C₂T_x nanocomposites as a portable power supply but also indicates its great opportunities in energy-saving H₂ production in practical applications.     

In-situ construction of Mn–Fe mixed oxides nanoparticles on reduced graphene oxide with superior lithium storage property

In this paper, porous Mn₃O₄–Fe₃O₄ nanoparticles with highly uniform composition are in-situ anchored on reduced graphene oxide (rGO) nanosheets by a simple cyanometallic framework template method. Thanks to the synergistic effects between the porous Mn₃O₄–Fe₃O₄ nanoparticles and the well-conductive rGO nanosheets, the Mn₃O₄–Fe₃O₄/rGO composites present superior electrochemical lithium storage performances with a great reversible capacity of 1013 mAh g^?1 after 100 cycles at 0.1 A g^?1, satisfactory rate capability of 510 mAh g^?1 at 3.0 A g^?1, and eminent long-term cycle stability of 804 mAh g^?1 after 500 cycles at 0.5 A g^?1. It is demonstrated that the rGO can not only act as a conducting matrix, but also buffer the volume expansion and avoid the aggregation of the Mn₃O₄–Fe₃O₄ nanoparticles during charging-discharging. The work provides a simple strategy for designing and fabricating advanced multi-component metal oxide-based anodes for high-performance lithium-ion battery.     

Hybrid high performance supercapacitor based on zeolitic imidazolate frameworks-67-derived nano-structure NiCo2S4

In this work, NiCo₂S₄, nickel-cobalt layered double hydroxides (NiCo-LDH) and CoS₂ electrodes are successfully prepared by using ZIF-67 as the precursor, the results show that NiCo-LDH and NiCo₂S₄ are nano-flower-like structures and CoS₂ exhibits a nano-cage structure. The electrochemical properties of the hybrid supercapacitor assembled with NiCo₂S₄ and activated carbon (AC) as electrodes were tested. As the positive electrode of NiCo₂S₄//AC hybrid supercapacitor, the NiCo₂S₄ electrode has the largest specific capacity of 2934 mAh g^?1 at a current density of 1 A g^?1. The NiCo₂S₄//AC capacitor generates the highest energy density of 38.8 Wh kg^?1 when the power density is 993.0 W kg^?1 and has a nice cycling performance with a capacity retention rate of 81.2% after 10,000 cycles at 5 A g^?1.     

Solvothermal synthesis of novel pod-like MnCo2O4.5 microstructures as high-performance electrode materials for supercapacitors

MnCo₂O_4.5 pod-like microstructures were successfully prepared through an initial solvothermal reaction in a mixed solvent containing water and ethanol, and combined with a subsequent calcinations treatment of the precursors in air. The total synthetic process was accomplished without any surfactant or template participation. The MnCo₂O_4.5 pods possessed a specific surface area as high as 73.7 m²/g and a mean pore size of 12.3 nm. The electrochemical performances were evaluated in a typical three-electrode system using 2 M of KOH aqueous electrolyte. The results demonstrated that such MnCo₂O_4.5 pods delivered a specific capacitance of 321 F/g at 1 A/g with a rate capability of 69.5% at 10 A/g. Moreover, the capacitance retention could reach 87% after 4000 cycles at 3 A/g, suggesting the excellent long-term cycling stability. Furthermore, the asymmetric device was fabricated by using MnCo₂O_4.5 porous pods as anode and active carbon as cathode. It could deliver a specific capacitance of 55.3 F g⁻¹ at 1 A g⁻¹ and an energy density of 19.65 W h kg⁻¹ at a power density of 810.64 W kg⁻¹. Such superior electrochemical behaviors indicate that the MnCo₂O_4.5 pods may be served as a promising electrode material for the practical applications of high-performance supercapacitors. The current synthesis is simple and cost-effective, and can be extended to the preparation of other binary metal oxides with excellent electrochemical properties.     

Constructing 3D honeycomb-like CoMn2O4 nanoarchitecture on nitrogen-doped graphene coating Ni foam as flexible battery-type electrodes for advanced supercapattery

Reasonable structural design is significant to enable the performance in advanced energy storage devices. Herein, a 3D honeycomb-like CoMn₂O₄ nanoarchitecture (CMO) on nitrogen-doped graphene (NG) coating Ni foam (denoted as Ni/NG/CMO) flexible battery-type electrode was prepared by a facile two-step hydrothermal strategy. The honeycomb-like CoMn₂O₄ arrays not only provide abundant active sites but can also be closely combined with the Ni foam/NG substrate, which enables high reversible capacity and good cycle stability during the long cycles. Benefiting from the compositional features and 3D honeycomb-like nanoarchitecture, the Ni/NG/CMO composite electrode displays improved electrochemical performance with remarkable specific capacity of 527.0C g⁻¹ at a current density of 1 A g⁻¹, outstanding rate capability (338.6C g⁻¹ even at 20 A g⁻¹). In addition, a flexible binder-free supercapattery device has been assembled with Ni/NG/CMO as positive electrode and 3D Ni/NG as negative electrode. Such a supercapattery delivers a high energy density of 44.1 Wh·kg⁻¹ at 992.6 W kg⁻¹, 20.3 Wh·kg⁻¹ at 12430.0 W kg⁻¹ as well as excellent cycling durability. The 3D honeycomb-like Ni/NG/CMO could be considered as an advanced flexible battery-type material for high capacity and energy density fields.     

Interconnected NiS-nanosheets@porous carbon derived from Zeolitic-imidazolate frameworks (ZIFs) as electrode materials for high-performance hybrid supercapacitors

Nickel sulfide-based materials have shown great potential for electrode fabrication owing to their high theoretical specific capacitance but poor conductivity and morphological aggregation. A feasible strategy is to design hybrid structure by introducing highly-conductive porous carbon as the supporting matrix. Herein, we synthesized hybrid composites consisting of interconnected NiS-nanosheets and porous carbon (NiS@C) derived from Zeolitic-imidazolate frameworks (ZIFs) using a facile low-temperature water-bath method. When employed as electrode materials, the as-prepared NiS@C nanocomposites present remarkable electrochemical performance owing to the complex effect that is the combined advantages of double-layer capacitor-type porous carbon and pseudocapacitor-type interconnected-NiS nanosheets. Specifically, the NiS@C nanocomposites exhibit a high specific capacitance of 1827 F g⁻¹ at 1 A g⁻¹, and excellent cyclic stability with a capacity retention of 72% at a very high current density of 20 A g⁻¹ after 5000 cycles. Moreover, the fabricated hybrid supercapacitor delivers 21.6 Wh kg⁻¹ at 400 W kg⁻¹ with coulombic efficiency of 93.9%, and reaches 10.8 Wh kg⁻¹ at a high power density of 8000 W kg⁻¹, along with excellent cyclic stability of 84% at 5 A g⁻¹ after 5000 cycles. All results suggest that NiS@C nanocomposites are applicable to high-performance electrodes in hybrid supercapacitors and other energy-storage device applications.     

Gamma-ray-irradiated construction of CuCo-based nanocomposites for attractive hydrogen production and tandem hydrogenation

Nitroarenes are important chemicals but display toxity to environment and organisms. In the present work, non-precious bicomponent CuCo-based nanocomposites (CuCo₂O₄/CuO) prepared with the aid of gamma(γ)-ray-irradiation were utilized for hydrogen production from ammonia borane (AB) hydrolysis and tandem hydrogenation of nitroarenes. The γ-ray-irradiation remarkably boosted the catalytic performance for the AB dehydrogenation and the hydrogenation of nitroarenes. Hydrogen generation rate (HGR) for the CuCo₂O₄/CuO catalyst reached 856.3 mL min⁻¹·g_cat⁻¹, which was approximately two-fold than that of the catalyst prepared by conventional method (only 397.1 mL min⁻¹·g_cat⁻¹). Meanwhile, this irradiation-induced catalyst also showed excellent performance for the hydrogenation of screened nitroarenes with 100% yield of the corresponding amines. The CuCo₂O₄/CuO catalyst exhibited high reusability with ∼90% remained activity of the initial one after six runs. The bicomponent CuCo₂O₄/CuO exhibited positive hydrogen spillover and synergistic effects contributing to the considerable activity improvement, which is beneficial to the detoxication, conversion and utilization of poison nitroarenes.     

Facile fabrication of comb-like porous NiCo2O4 nanoneedles on Ni foam as an advanced electrode for high-performance supercapacitor

It is very desirable to develop the high-performance supercapacitors to meet the rapidly growing demands for energy-autonomous operation and miniaturization of devices. Herein, comb-like porous NiCo₂O₄ nanoneedles on the three-dimension (3D) nickel foam (NF) have been successfully synthesized through a facile pulsed laser ablation (PLA) approach without any post-treatments and surfactant (denoted as NiCo₂O₄-PLA). The influence of working solution during the fabricated process on the properties of NiCo₂O₄-PLA has been demonstrated in detail in terms of the crystalline structure, specific surface area, morphology, and electrochemical performance. Benefiting from the large specific surface (261.4 m² g⁻¹), abundant pores, and highly conductive scaffold, the NiCo₂O₄-PLA binder-free electrode exhibits an outstanding specific capacitance (1650 F g⁻¹ at a current density of 1 A g⁻¹) and eminent cycling performance (91.78% retention after a 12,000-cycle test at a current density of 10 A g⁻¹) compared with the control samples. The assembled asymmetric device (NiCo₂O₄-PLA//AC-ASCs) delivers the high specific capacitance of 126.9 F g⁻¹ at the current density of 1 A g⁻¹, the large energy density of 56.7 Wh kg⁻¹ at a power density of 756 W kg⁻¹, and the low internal resistance. The attractive results strongly prove that it is an ideal candidate for advanced supercapacitor application.     

Synthesis of CuCo2S4 nanosheet arrays on Ni foam as binder-free electrode for asymmetric supercapacitor

Recently more and more concerns have been paid on ternary metal sulfides for use in supercapacitors because of their better electrochemical performances compared with binary counterparts. In this work, CuCo₂S₄ nanosheet arrays on Ni foam were prepared by a sequential ion-exchange strategy under hydrothermal conditions, where Co₃O₄ was converted into Co₄S₃ by an anion-exchange reaction between Co₃O₄ and S^2? ions, subsequently the Co₄S₃ was transformed into CuCo₂S₄ through a cation-exchange reaction with Cu²⁺ ions. The as-prepared CuCo₂S₄ was characterized by powder X-ray diffraction, high-resolution X-ray photoelectron spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. The CuCo₂S₄ arrays were composed of interconnected thin nanosheets with thickness of about 10 nm. The CuCo₂S₄ nanosheet arrays on Ni foam were directly employed as a binder-free electrode showing a high specific capacitance of 3132.7 F g^?1 at a current density of 1 A g^?1. Besides, an asymmetric supercapacitor based on this synthesized CuCo₂S₄ electrode as positive electrode and active carbon as negative electrode can deliver a high energy density of 46.1 Wh kg^?1 at a power density of 991.6 W kg^?1, and exhibits good rate capability and cycling stability.     

Optimizing electrochemical performance of sonochemically and hydrothermally synthesized cobalt phosphate for supercapattery devices

The supercapattery (hybrid energy storage device) has procured miraculous heed for their significant electrochemical performance, constitute combine features of supercapacitor (prodigious power density) and batteries (substantial energy density), still crave for electrode material with better electrochemical conduct. Here, cobalt phosphate ((Co₃(PO₄)₂) nanostructures were synthesized using sonochemical and hydrothermal approach. The SEM, XRD, and EDX were employed to explore surface morphology, crystal structure, and elemental analysis respectively of as synthesized nanomaterials. The electrochemical performance was evaluated in two and three electrode assembly. The maximum specific capacity of 285 C g^-1 at 3 mV/s and 221 C g^-1 at 4.1 A g^-1 has been obtained by sonochemically synthesized nanomaterial (S1). This electrode material with optimum electrochemical performance was further investigated for supercapattery application. Asymmetric device was fabricated, comprising activated carbon as negative and S1 as positive electrode material. The supercapattery device exhibits a specific capacity of 147.2 C g^-1 bearing an outstanding energy density of 34.8 Whkg^?1 with a power density of 425.0 W kg^-1 at 0.5 A g^-1. The device was found to have a remarkable power density of 6800.0 W kg^-1 while retaining an energy density of 10.0 Whkg^?1 with exceptional capacity preservation of 87.2% after 10,000 consecutive GCD cycles even at 8.0 A g^-1. The device performance was further explored in terms of capacitive and diffusion controlled processes and found to have a maximum capacitive contribution of 63.8% at 100 mV s^-1. The sonochemical method was found to be the optimal route to synthesize nanomaterials for energy storage applications.     

A comparative study of various polyelectrolyte/nanocomposite electrode combinations in symmetric supercapacitors

A more practical, nontoxic and cheaper electrolyte, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) was used to construct supercapacitors with different nanocomposite electrodes. The flexible devices were fabricated including active carbon (AC) electrode and nanocomposites electrodes of AC/nano-silica (nano-SiO₂) and AC/multiwalled carbon nanotubes (MWCNTs) at various weight percentages. The symmetrical cell made from AC electrodes generated a maximum specific capacitance (Cs) of 315 F g⁻¹ at 0.5 A g⁻¹. The energy density of this device was 55.5 Wh kg⁻¹ at a power density of 690 W kg⁻¹. Excellent performance was achieved after 5000 charge-discharge cycles where the supercapacitor maintains 92% of its activity. The energy storage capability of the supercapacitors was also investigated with the addition of nano-SiO₂ and MWCNTs. The Cs of the supercapacitors made with the electrodes AC/nano-SiO₂ (5%, 10%, 25% and 50%) were 172, 228, 247 and 55 F g⁻¹, respectively. Similarly, the capacity of the device including the electrodes of AC/MWCNTs (5%, 10%, 25% and 50%) varied as 191, 244, 93 and 20 F g⁻¹ at 0.5 A g⁻¹. The maximum energy density of the devices having nano-SiO₂ and MWCNT were 44.4 Wh kg⁻¹ and 43.8 Wh kg⁻¹, respectively at a power density of 520 W kg⁻¹. A supercapacitor with certain dimension successfully operated a light-emitting diode (LED).     

Facile sonochemical synthesis of strontium phosphate based materials for potential application in supercapattery devices

Among hybrid energy storage devices, supercapattery gained profound research interest due to its ability to give high energy density while maintaining the power density and cyclic stability. Herein, novel low-cost strontium based materials are synthesized by controlled sonochemical method and subsequently calcined at various temperatures. The multiple phases of the material synergistically contributed in the electrochemical charge storage process and give high specific capacity of 220 C g⁻¹ (as-prepared material) and 213 C g⁻¹ (calcined at 200 °C) at 0.5 A g⁻¹. A thorough electrochemical performance of optimized material is investigated as an electrode in asymmetric device. The supercapattery (SP2//AC) exhibits a specific capacity of 103.4 C g⁻¹ at 0.5 A g⁻¹ in the voltage range of 0–1.7 V. Furthermore, supercapattery offers a considerably high specific energy of 24.4 Wh kg⁻¹ at a specific power of 425 W kg⁻¹ and an excellent specific power of 1870 W kg⁻¹ by maintaining specific energy at 14.5 Wh kg⁻¹. In addition, the device retained its specific capacity to 90% after 3000 charging/discharging cycles at 1 A g⁻¹. Strontium based materials could be proposed as an appropriate electrode material for energy storage systems.     

Electrodeposited nickel nanocone/NiMoO4 nanocomposite designed as superior electrode materials for high performance supercapacitor

A nickel nanocone-modified NiMoO₄ hybrid (NiMoO₄/NNC) on Ni foam (NF) substrate is engineered to enhance the capacitance performance of NiMoO₄ via facile and convenient electrodeposition strategy, followed by hydrothermal method. The presence of nickel nanocone (NNC) increases the density of reaction active sites of NiMoO₄/NNC/NF, which can shorten the charge diffusion pathway and boost ionic/electronic conductivities. As expected, the NiMoO₄/NNC/NF, as a prospective electrode material, presents appreciable electrochemical properties. Remarkably, the NiMoO₄/NNC/NF electrode demonstrates a high specific capacitance of 2813 F g^?1 at 3 A g^?1 and manifests considerable cycling durability with a retention of 94% of the initial capacitance over consecutive 5000 cycles. Furthermore, a NiMoO₄/NNC/NF//AC/NF asymmetric supercapacitor displays a great electrochemical performance by delivering high energy density (43 Wh kg^?1) and power density (821 W kg^?1) as well as notable durableness (10% decay after 5000 cycles). The presented results suggest that NiMoO₄/NNC/NF can be considered as a binder-free electrode for highly stable supercapacitors.