High Energy Density Hybrid Supercapacitor Research Articles

Versailles Santa Barbara-5 derived bifunctional one-dimensional electrocatalysts of hierarchical Ni3S2 nanoprism@nanosheets arrays for self-supporting and binder-free efficient supercapacitor and methanol oxidation reaction

We herein present a structure consisting of two-dimensional (2D) single-crystal Ni3S2 nanosheets designed on one-dimensional (1D) Ni3S2 nanoprism arrays (also known as Ni3S2 nanoprism@nanosheets). These arrays are directly synthesized over nickel foam, which is referred to as Ni3S2/NF. These structures can be used as binderless, self-supporting electrodes for bifunctional methanol oxidation reaction (MOR) applications and high energy density hybrid supercapacitors (HSC). Ni3S2/NF is synthesized through the two steps of hydrothermal processes. In step I, 1D hexagonal Versailles Santa Barbara-5 (VSB-5) nanorod arrays have been prepared onto the surface of NF (denoted as VSB-5/NF). The precursor for step II was 1D VSB-5 nanorod arrays, which were transformed into Ni3S2 using Na2S as a sulfur source via the Kirkendall effect. Electrochemical examination results show that as-synthesized Ni3S2/NF electrode exhibited a high specific capacitance (Cs) of 145.0 mA h g−1 at 5 A g−1, low series resistance (0.18 Ω) and charge-transfer resistance (0.05 Ω), small relaxation time constant (τ0 = 8 ms) and high frequency response at 125.8 Hz. Ni3S2/NF has a superior specific capacity of 145.0 mA h g−1 at 5 A g−1 as a SC electrode. The Ni3S2/NF//CNTs/NF HSC can be operated up to 1.6 V in a 3 M KOH electrolyte, delivering an impressive energy density of 256.35 W h kg−1 at a power density of 6400 W kg−1. The as-assembled Ni3S2/NF//CNTs/NF HSC device exhibited an impressive stability of 81 % even after undergoing 10,000 charge-discharge cycles. When compared to previously reported catalysts, Ni3S2/NF was proved to be an excellent electrocatalyst for MOR due to its ability to generate a current density of 215.0 mA cm−2 at 0.5 VSCE, while maintaining a superior and stable current density of 619.2 mA cm−2 at 0.8 VSCE.

Designing hybrid electrode materials comprising of interface‐engineered hierarchical structure and its synergetic effect on high energy density hybrid supercapacitors

Rational interface tailoring of nanomaterials is promising but still challenging for high performance electrodes for energy storage applications. Herein, we demonstrate the rational design of hierarchical porous hybrid nanostructure with robust adhesion on Ni foam as a binder-free electrode for supercapacitors (SCs). The incorporation of the carbon nanomaterial and conducting polymers into spinel metal oxide greatly boost the charge transfer. The synergistic effect among individual components maximizes accessible electroactive sites results in a supercapacitor material with superior electrochemical properties. Benefiting from the synergistic interaction, the novel RuCo2O4/RGO/PANI hybrid manifests a high specific capacity of 1028.7 C g−1 at 1 A g−1 and the best cycle stability (93.2 % after 10,000 cycles), which far outperforms the previously reported electrodes in 2 M KOH. The SC device with the newly developed RuCo2O4/RGO/PANI hybrid cathode and graphene anode achieves an exceptional energy density of 36.7 W h kg−1 at a power density of 800.4 W kg−1, as well as capacity retention of 90.1 % after 10,000 cycles. Our findings hold great promise of RuCo2O4/RGO/PANI hybrid for the use in next generation energy storage devices.

Fabrication of (Ag, Zn, Co) based spinel ferrites as electrode materials for high energy density hybrid supercapacitors

Three spinel ferrites, AgFe2O4, CoFe2O4, and ZnFe2O4, were successfully synthesized using the hydrothermal technique and were employed as electrode materials for supercapacitor applications. These spinel ferrites underwent a comprehensive assessment of their crystallinity, morphology, and electrochemical performance. The structural analysis using X-ray diffraction convincingly demonstrated the excellent crystallization of these compounds, indicating the development of single-phase spinel ferrites. A uniform cubic structure was successfully achieved. TEM analysis revealed that the as-synthesized nanomaterials exhibited a spherical shape with particle sizes ranging from 50 to 100 nm. In terms of electrochemical performance, utilizing a three-electrode configuration, the cubic spinel CoFe2O4 nanoparticles, synthesized at 200 °C, exhibited outstanding results, with a maximum specific capacitance of 2146.40 F/g at 3 mV/s, surpassing the performance of AgFe2O4 and ZnFe2O4. To create a hybrid asymmetric device utilizing all three spinel ferrites, activated carbon served as the negative electrode, while AgFe2O4, CoFe2O4, and ZnFe2O4 were employed as positive electrodes. Notably, the CoFe2O4 electrode outperformed the others, achieving a remarkable 94 % coulombic efficiency and demonstrating long-term cyclic stability with 87 % capacitance retention after 10,000 cycles. The findings of this study underscore the significant potential of the synthesized nanoparticles as promising candidates for hybrid supercapacitors and various other electrochemical applications.

Carbon fiber composite electrodes derived from metal organic polyhedra-18 and matrimid for hybrid supercapacitors

Matrimid and metal–organic polyhedra-18 (MOP-18) electrospun composite nanofibers were utilized to fabricate free-standing, electrically conducting, and high-energy density hybrid supercapacitor electrodes.

Unification of DAQ-rGO-PEDOT as binder-free ternary nanocomposite electrode for high performance solid-state symmetrical supercapacitor

A high energy density hybrid supercapacitor has been developed from highly π-conjugated 1,4-diaminioanthraquinone covalently bonded to reduced graphene oxide (DAQ:rGO). The drop casting of DAQ:rGO suspension onto nanostructured PEDOT matrixes has enhanced the microstructure/orderliness, higher homogeneity as confirmed by Raman, FE-SEM and HRTEM studies. The high gravimetric capacitance (622.4 F g−1 at 1 A g−1) emerges from extensively porous matrix of nanostructured PEDOT and low band gap of DAQ:rGO evident from a voltage window of -0.2 to 0.8 V facilitating the redox activity of DAQ. In addition, solid-state symmetric supercapacitor based on ternary electrode with free standing PVA-H2SO4 gel electrolyte possesses specific capacitance of 492.5 F g−1 at 1.5 A g−1 with exceptional energy density (68.39 W h kg−1) and excellent cyclic stability (retaining 100% capacitance after 10,000 cycles. The ability of the four devices to illuminate the LED for 120 s manifests utility of the nanocomposite for future microelectronics.

Enhanced electrochemical activity of two dimensional layered bismuthene-MWCNT heterostructures based electrodes for the fabrication of high energy density hybrid supercapacitors

Advanced two dimensional nanostructures with distinctive physicochemical properties, excellent surface chemistry, and adjustable interlayer band-gap enhances the electrochemical activity in the field of supercapacitors. This work focuses on the formation of the hybrid nanocomposite of Bismuthene-Multiwall carbon nanotube nanocomposite (Biene-MWCNT NC) to enhance the electrochemical activity. Cyclic Voltammetry (CV) analysis of Biene-MWCNT NC reveals the enhanced specific capacity of 323.65 C/g at the scan rate of 10 mV/s. In addition, the Trasatti method shows the charge accumulation mechanism which delivering the total, inner, and outer capacity of 662.3, 601.02, and 61.23 C/g respectively together with the capacity and diffusion contribution percentages of 90.76 % and 9.24 % correspondingly. Furthermore, Biene-MWCNT//MWCNT hybrid supercapacitor (HSC) demonstrates the elevated specific capacity of 113.85 C/g at the constant current density of 0.5 A/g and the outstanding energy density of about 35.5 Wh/kg corresponds to high power density of 11250 W/kg.

Enhanced electrochemical activity of PVA assisted CuFe2O4 nanoparticles as a potential electrode for the fabrication of high energy density hybrid supercapacitor

Magnetic nanomaterials with unique physicochemical properties create a new era by providing enhanced electrochemical activity in the field of supercapacitors. In this work, the polyvinyl alcohol assisted copper ferrite (CFO-PVA) nanoparticles have been synthesized simple co-precipitation technique. The supercapacitor electrode materials have been fabricated by CFO-PVA electrode, delivering a high specific capacity of 169 C/g at 10 mV/s. based on the Trasatti method, the charge accumulation process has been identified and the total, outer, and inner capacities of CFO-PVA are 595.23, 8, and 587.23 C/g correspondingly and their contributions of capacitive and diffusion are 98% and 2% respectively. In addition, the CFO-PVA//AC hybrid supercapacitor device (HSC) has been prepared and their maximum specific capacitance is to be 60 C/g at the current density of 1 A/g together with their high energy density of about 18.75 Wh/kg and their respective high power density of 3012 W/kg.

Composition engineering strategy of carbon–coated bimetallic phosphide for high energy density hybrid supercapacitors

Bimetallic phosphides hold great promise for using in hybrid supercapacitors (HSCs) as electrode material due to their synergistic effect of hetero-metal ions in ameliorating specific capacity and electrical conductivity. The production of bimetallic Ni1-xCoxP nanocrystals based on carbon-coated (Ni1-xCoxP@C) is described, and their potential application as positive electrodes in HSCs is also discussed. We give an insight into the significance of composition engineering for nickel-cobalt bimetallic phosphides in obtaining excellent electrochemical performance for supercapacitors. Ni0.9Co0.1P@C electrode reaches a maxima specific capacity as high as 4250 ± 48 mC cm−2 at 1 mA cm−2 (1327 ± 15 C g−1 at 1 A g−1), outperforming most transition metal phosphides (TMP)-based electrodes reported recently. Utilizing Ni0.9Co0.1P@C as electrode, the obtained HSC device provides a desired energy density of 46.9 ± 2.2 Wh kg−1 at 1600 W kg−1 and continues to sustain 26.2 ± 1.3 Wh kg−1 at a significant power density of 8000 W kg−1, capacitance retention remaining at 89.4 % after 10,000 cycles. It is believed that the Ni0.9Co0.1P@C has significant promise for application in extremely effective and affordable HSCs, as well as probably in other energy storage devices.

High energy density hybrid supercapacitors based on graphitic carbon nitride modified BiFeO3 and biomass-derived activated carbon

One of the major challenges to the commercialization of supercapacitors (SCs) remains the low energy density, especially at high current densities. Electrode materials with a wide operating voltage and high capacitance are promising for addressing this challenge. Bismuth ferrite (BiFeO3) is utilized as a battery-type electrode which exhibits a wide voltage window and high specific capacitance by storing charge through reversible redox reactions. In this study, bismuth ferrite functionalized with graphitic carbon nitride (g-C3N4) is synthesized by hydrothermal and ball milling techniques to form the cathode for hybrid SCs. As anode, biowaste-derived activated carbon is synthesized from orange peels via a sequential carbonization and activation process. The device exhibits a high specific capacitance of 330 F/g, excellent energy density of 244.8 Wh kg−1 and power density of 1.155 kW kg−1 at a current density of 1 A g−1. An innovative pathway has been developed for designing and fabricating asymmetric supercapacitors with high energy density. The assembled device provides a high operating voltage window of 2.4 V, opening up new possibilities for high-voltage high performance energy storage devices.

MOF-derived (Ni, Co)Se2 @CoP/CNFs@CF with enhanced reaction kinetics by heterointerface engineering for high-performance hybrid supercapacitors

Ni/Co selenide (NCSe), which has a high theoretical capacity and a lot of redox activity, is a candidate for high-performance supercapacitor electrode materials. With its poor reaction kinetics, it performs electrochemically much less efficiently than it should. Herein, we first synthesized MOF-derived zero-dimensional (0D)/two-dimensional (2D) (Ni, Co)Se2 @CoP/CNFs@CF (carbon and nitrogen framework) hierarchical heterogeneous nanosheet arrays. The charge transport is accelerated by the Coulomb forces of the built-in electric field created by the electron rearrangement at the heterointerface of (Ni, Co) Se2 @CoP/CNFs@CF. Moreover, the 0D/2D micro-nanostructure promotes interlayer shuttling and the penetration of electrolyte ions while combining the benefits of 0D and 2D materials. The two synergistically accelerate the reaction kinetics of the electrode. As expected, (Ni, Co)Se2 @CoP/CNFs@CF has an excellent specific capacity (431.7 mAh g−1, 1 A g−1). In addition, the hybrid supercapacitor (Ni, Co)Se2 @CoP/CNFs@CF//AC (activated carbon) has an ultra-high energy density (85.31 Wh kg−1, 800 W kg−1) and cycling stability (10,000 cycles, 113.72%). This is the P/Se hybrid metal compound electrode's best electrochemical performance to date. This work offers a method for fabricating electrodes with heterostructures for high energy density hybrid supercapacitors by enhancing the attributes of the electrode structure and interface.

CoNi bimetallic engineering on porous carbon for high energy density hybrid supercapacitors

Rationally designed, structurally stable, and high-capacity transition metal alloy decorated carbon composites have attracted considerable attention as electrode materials for high-performance hybrid supercapacitors (HSCs). A unique electrode material composed of mixed transition metals (Co and Ni) on fryums-derived porous carbon was synthesized using a facile one-step pyrolysis approach. The CoNi@C composite exhibited rich redox kinetics and good electrochemical performance in an aqueous alkaline electrolyte. In particular, the CoNi@C composite delivered a maximum specific capacity of 390 mA h g−1 at 1 A g−1 with good capacitance retention of 91 % over 5000 cycles. The gravimetric specific capacity of the CoNi@C composite was 1.3 times better than that of the single alloy composite. Moreover, the HSC fabricated with CoNi@C, and activated carbon electrodes exhibited a high energy density of 57.6 Wh kg−1 at a power density of 742 W kg−1 and good cycling stability with a low-capacity loss of 8 % after 5000 cycles. Utilizing high-voltage and energy density, the HSCs can power light-emitting diodes of different wavelengths, demonstrating its practical applicability in energy storage technologies. The structural verification of fryum-derived carbon revealed a good graphitization degree, ensuring its remarkable adaptability for device fabrication.

Assembling zinc cobalt hydroxide/ternary sulfides heterostructure and iron oxide nanorods on three-dimensional hollow porous carbon nanofiber as high energy density hybrid supercapacitor

The critical challenge of supercapacitors lies in sluggish kinetics of electrodes and undesirable specific capacitance during charge discharge process including large volume change and inferior cyclic stability. In this work an elaborately designed three dimensional hierarchical heterostructure comprising ternary metal sulfides completely covered by nickel cobalt layered double hydroxide (NiCo-LDH@ZNCS) core shell arrays on electrospun three-dimensional hollow porous carbon nanofiber and used as free-standing electrode material for supercapacitors. The original built-in interfacial potential between NiCo-LDH and ZNCS on conducting three dimensional hollow PCF can acquire multidimensional channels for ion/electron transfer and validate to be a highly capacitive cathode material with a high specific capacity of 407.11 mA h g−1 at the current density of 1 mA cm−2 maintaining outstanding rate performance. The iron oxide nanorods (Fe2O3-PCF) anode (216.15 mA h g−1 at the current density of 1 mA cm−2) match well to the cathode. Benefiting from the powerful synergistic effect, the assembled quasi solid state asymmetric supercapacitor can deliver ultrahigh energy density of 111.72 W h kg−1 at a power density of 243 W kg−1 and extra ordinary life cycle stability (95.2 % capacity retention after 20,000 charge discharge cycles). Such superior electrochemical performances are attributed to the multidimensional nanostructures, porous carbon networks, improved conductivity, and synergistic interaction between the active components of NiCo-LDH/ZNCS arrays. This approach provides a new perspective for rational design of high energy density hybrid supercapacitors, holding unbounded possibilities in this energy dependent world.

Integrating the essence of metal organic framework-derived ZnCoTe–N–C/MoS2 cathode and ZnCo-NPS-N-CNT as anode for high-energy density hybrid supercapacitors

Transition bimetallic compounds are exploited as high-capacity electrode materials for supercapacitors due to their abundant electroactive sites and electrical conductivity. However, it remains grand challenge to construct supercapacitor devices that deliver high energy density. Here, we report an attractive one-stone-two-birds strategy to develop metal organic frameworks (MOFs) derived cathodes and anodes consisting of zinc cobalt telluride integrated nitrogen doped carbon (ZnCoTe–N–C) and zinc cobalt nanoparticles encased nitrogen doped carbon nanotubes (ZnCo-NPs-N-CNTs), respectively. Particularly, ZnCoTe–N–C cathode exhibited high specific capacity of 192.77 mA h g−1, which was further improved by the presence of hierarchical molybdenum disulfides (MoS2) nanosheets. Increased electrochemical active sites provided by MoS2 nanosheets energizes both the capacity and stability of the electrode. Consequently, the ZnCoTe–N–C/MoS2 electrodes showed a higher specific capacity of 342.55 mA h g−1 as well as excellent long-term stability. Besides, the ZnCo-NPs-N-CNTs demonstrated an initial capacity of 207.22 mA h g−1 and retained a high specific capacity even after 50 A g−1. The excellent electrochemical activity of the electrodes is attributed to the incorporation of redox rich bimetallic components and nitrogen rich carbon directly grown on the current collector, which reduces the dead volume and avoids volume expansion during charge discharge process. Finally, a hybrid asymmetric supercapacitor (HASCs) assembled using ZnCoTe–N–C/MoS2 and ZnCo-NPs-N-CNTs delivered a high specific energy density and power density maintaining 93.6% of its capacitance after 20,000 cycles. This study expands a way to construct a hybrid supercapacitor with well-designed structure and superior performance for clean energy storage technologies utilizing minimum resources.

Two-Dimensional Layered Bismuthene/Antimonene Nanocomposite as a Potential Electrode Material for the Fabrication of High-Energy Density Hybrid Supercapacitors

Advanced two-dimensional (2D) materials with excellent physicochemical properties create huge interest in developing high-energy-density supercapacitors without diminishing their power densities. Herein, a novel bismuthene/antimonene nanocomposite (Biene/Sbene NC) has been employed as an efficient active material to fabricate supercapacitor electrodes with excellent electrochemical performance. As a result, the Biene/Sbene electrode delivers a high specific capacity of 1003.3 C/g at a scan rate of 10 mV/s and an outstanding cycling stability of 87.3% for 10,000 charge–discharge cycles. Moreover, the composite electrode provides the total, outer, and inner capacity of 2857.14, 80, and 2777.14 C/g respectively based on Trasatti analysis and their capacitive and diffusion contributions of 97.2 and 2.8% correspondingly. The hybrid supercapacitor (HSC) has been fabricated by the Biene/Sbene NC cathode and activated carbon (AC) anode which demonstrates a high energy density of 131.44 Wh/kg and a maximum power density of 8262.2 W/kg. In addition, the Biene/Sbene//AC HSC demonstrates practical utilization by illuminating the red light-emitting diodes for 5 min by interconnecting three HSCs in series. This work will stimulate an alternate idea to fabricate electrode materials by utilizing novel 2D materials with excellent physicochemical properties for next-generation energy storage devices.

Rational design and facile synthesis of Ni-Co-Fe ternary LDH porous sheets for high-performance aqueous asymmetric supercapacitor

Reasonable construction of microstructure and successful combination of multiple components provide an extensible strategy for the exhibition of electrode materials in asymmetric supercapacitors (SCs). Lately, transition-metal-based ternary layered double hydroxides (LDHs) have evoked substantial focus in the area of supercapacitor by reason of their excellent features such as tunable chemical composition and a high electro-chemical competence. In order to make certain the impact of metal proportion on electrochemical performance of LDHs, herein, two-dimensional porous NixCo1-xFe-LDHs (NixCo1-xFe-LDH, x = 0, 0.25, 0.75, 1) nanosheets are synthesized by a succinct-operated hydrothermal method to employ in high energy density hybrid supercapacitor (HSC). The molar ratio of NiCoFe-LDH compounds is regulated and researched the difference of structural, morphological, and electrochemical properties by the numbers, subsequently compared with their binary counterparts. Here we demonstrate that the higher the nickel content is, the higher the specific capacity is of LDH so that NiCoFe-LDH product renders a large capacitance of 425.56 mAh·g−1 at a current density of 1 A·g−1 with 94.52% capacitance retention observed at 10 A·g−1. Moreover, the trimetallic CoNiFe-LDH are more effective in boosting the SCs performance than the two sets of bimetallic LDHs. An aqueous HSC device is composed of NiCoFe-LDH and activated carbon (AC) which displays a high energy density (51.82 Wh·kg−1) at a power density of 1.26 kW·kg−1 with outstanding cycle stability (95.16 % after 10,000 cycles). The excellent NiCoFe-LDH electrode material is hopeful for high-property SCs.

Rationally designed metal–organic framework templated iron-molybdenum sulfide for high energy density hybrid supercapacitors

The rational design of high-performance electrodes is of major significance for the fabrication of advanced energy storage technologies. Herein, surface engineering has been extensively implemented to obtain nonprecious metal organic frameworks (MOFs) as a template, to carry out in-situ growth of iron molybdenum sulfide on nickel foam (denoted as Fe-MoS2@NF). The novel architecture of the synthesized electrode demonstrates a high-performance supercapacitor. Fe-MoS2@NF electrode delivers a high areal capacity of 3565 mC cm−2 at a current density of 4 mA cm−2 in 6 M KOH aqueous electrolyte and retains 89 % of areal capacity after 5000 cycles. In addition, a hybrid supercapacitor (HSC) was fabricated comprising the Fe-MoS2@NF and O, N, S@AC as positive and negative electrodes, respectively. The fabricated HSC exhibits a high specific capacity of 60 mAh g−1 at 1 A g−1 and delivers an excellent specific energy of 49.4 Wh kg−1 corresponding to a specific power of 827 W kg−1 and maintains the specific energy of 10.2 Wh kg−1 at a high specific power of 13.42 kW kg−1. Moreover, the device showed a better cyclic stability ∼ 91 % for 10,000 charge/discharge cycles. Thus, the design concept of the electrode opens a new avenue towards the battery type supercapacitor applications.

Self-combustion synthesis of dilithium cobalt bis(tungstate) decorated with silver nanoparticles for high performance hybrid supercapacitors

Oxide materials LixMy(XO4)z (M = Ni, Co, Fe, Mn…) and (X = P, W, Mo, As) with an open frame structure are of great interest for electrochemical energy storage. In this work, a high energy density Hybrid supercapacitor (HSC) was fabricated by combining a battery-type (faradaic) Li2Co(WO4)2@Ag electrode with an Activated carbon (AC) as a capacitive type electrode (non-faradaic). First, the dilithium cobalt bis(tungstate), Li2Co(WO4)2, material was prepared by a facile chemical method (self-combustion), followed by coating with silver nanoparticles (Ag NPs) through reduction of silver ions (Ag+) using ethanol containing Polyvinylpyrrolidone (PVP) to improve the conductivity of the composite. The Li2Co(WO4)2@Ag electrode delivered a specific capacity almost two-times greater (1192C/g at a current density of 1 A/g) compared to the electrode without silver (631.2 C/g at 1 A/g) in an electrolyte of 6 M KOH aqueous solution, and also exhibited an excellent retention capacity of 85.2% after 10,000 cycles at 20 A/g. Furthermore, Li2Co(WO4)2@Ag//AC hybrid supercapacitor was assembled and delivered a high energy density of 89.33 Wh/kg at the power density of 800 W/kg. At a maximum power density of 8 kW/kg, the HSC provided an energy density of 58.66 Wh/kg along with an excellent capacity retention (83.4%) after 10,000 charge–discharge cycles at 5 A/g.

Hierarchical Architectured Dahlia Flower-Like NiCo2O4/NiCoSe2 as a Bifunctional Electrode for High-Energy Supercapacitor and Methanol Fuel Cell Application

We report unique hierarchical dahlia flower-like NiCo2O4 nanograss/NiCoSe2 nanosheets on Ni foam (NCO/NCS/NF) as bifunctional binder-free electrodes for high energy density hybrid supercapacitors and methanol electro-oxidation applications. NCO/NCS/NF is synthesized by a facile hydrothermal method followed by an electrodeposition process. As a supercapacitor electrode, NCO/NCS/NF exhibits a superior specific capacitance of 2045.5 F g-1 (227 mAh g-1 or 818 C g-1) at 1.8 A g-1. The assembly of a hybrid NCO/NCS/NF//AC device delivers impressive specific energy of 54.5 Wh kg-1 at 350 W kg-1 with durable cyclic stability of 82.5% after 10,000 charge-discharge cycles. NCO/NCS/NF as an electrocatalyst toward methanol oxidation yields a high current density of 130 mA cm-2 at 0.5 V and a low onset potential of 0.13 V, in comparison to other reported catalysts. Such high electrochemical performance of a binder-free NCO/NCS/NF electrode is attributed to the synergistic effect between the bimetallic oxides and selenides, core-shell nanostructure, hierarchically aligned architectures of nanograss/nanosheets, and conductive coatings of NCS to provide rapid charge transfer reactions. To the best of author's knowledge, this is the first report of a 3D hierarchical NCO/NCS/NF 1D/2D nanostructure toward a bifunctional binder-free electrode for energy storage and conversion technologies.

MOF-derived Fe2O3 decorated with MnO2 nanosheet arrays as anode for high energy density hybrid supercapacitor

The strategy of complementing the optimal energy storage potential range is used to construct core–shell M−Fe 2 O 3 @MnO 2 as an advanced anode material. The M−Fe 2 O 3 @MnO 2 //NiCo 2 O 4 HSC delivers a high energy density of 86.8 Wh kg −1 , and two such devices can light 25 LEDs for more than 210 min. • Strategies for complementary energy storage potential interval. • MnO 2 nanosheet arrays decorate on Fe 2 O 3 driven by MOF. • The M−Fe 2 O 3 @MnO 2 has excellent specific capacitance of 908.5F g −1 . • M−Fe 2 O 3 @MnO 2 //NiCo 2 O 4 delivers a high energy density of 86.8 Wh kg −1 . • Two HSC devices can brighten 25 LEDs for more than 210 min. The development of high-performance anode materials to match the fast-burgeoning cathodes is essential for the fabrication of high-energy–density supercapacitors. Hematite Fe 2 O 3 , with ultra-high theoretical capacitance, has been considered as a promising anode candidate, but the insufficient utilization of the energy storage potential range (mainly in −1.1 V ~ -0.5 V) creates obstacles for further expansion of its electrochemical performance. In this work, a pinecone-like core–shell composite, with vertically grown MnO 2 nanosheet arrays decorated on the M−Fe 2 O 3 prepared via sacrificing the Fe-MOF (MIL-88A) template, was synthesized to achieve the excellent energy storage effect at a wide potential range from −1.1 V to 0.3 V. As adjusting the MnO 2 coating amount to a suitable level, the M−Fe 2 O 3 @MnO 2 composite exhibits a prominent specific capacitance up to 908.5F g −1 as well as excellent cycle stability. Pseudocapacitance analysis interprets the essence of the kinetics process of composite materials in the energy storage process. The hybrid supercapacitor (HSC), assembled with pinecone-like M−Fe 2 O 3 @MnO 2 as the anode and urchin-like NiCo 2 O 4 as the cathode, delivers a high energy density of 86.8 Wh kg −1 at 804.1 W kg −1 . Unsurprisingly, 25 parallel blue LEDs powered by two HSC devices can illuminate for over an astonishing 210 min. This work fabricates a promising anode material for high-energy–density hybrid supercapacitors, and the strategy of complementary energy storage potential provides a novel approach for constructing high-performance energy storage systems.

Anchoring nitrogen-doped carbon quantum dots on nickel carbonate hydroxide nanosheets for hybrid supercapacitor applications

With the ever-increasing demands for energy resources, the exploration of high energy density hybrid supercapacitors is urgently required. Herein, an effective hydrothermal strategy is demonstrated to construct advanced cathode of nickel carbonate hydroxide (NCH) ultrathin nanosheets anchored nitrogen-doped carbon quantum dots (NCQDs) for hybrid supercapacitors. It is revealed that the NCQDs are evenly deposited on the surface of NCH nanosheets, which provide abundant active sites for NCH nanosheets and endow them improved electrochemical characteristics. The NCH/NCQDs nanosheets deliver a decent electrochemical capacity of 727C g−1 at 1 A g−1 with ameliorative rate capability and cyclic stability. In addition, a hybrid supercapacitor device with an impressive energy density (49.1 Wh kg−1 at 700.3 W kg−1) and stable cycling property (87.5% after 8000 cycles) is fabricated by employing NCH/NCQDs nanosheets and p-phenylenediamine functionalized reduced graphene oxide (PRGO) as cathode and anode. These results indicate the great potential of NCH/NCQDs nanosheets for renewable energy storage.