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The hierarchically porous sulfide with abundant cavities contributes to high specific charge (872.0 C g−1 at 1 A g−1), the corresponding NiCoMnS//AC HSC device exhibited a high energy density of 47.2 Wh kg−1 at a power density of 750 W kg−1. [Display omitted] • The hierarchically porous NiCoMnS sulfide nanosheets were in situ synthesized on NF. • Sulfur source concentration played a vital role in constructing the nanosheets with abundant cavities in the post-sulfidation process. • The self-supporting NiCoMnS/NF exhibited an excellent conductivity and high specific charge. • Assembled NiCoMnS//AC HSC device delivered a high energy density of 47.2 Wh kg−1 at a power density 750 W kg−1. Ternary transition metal sulfides have attracted much attention due to their superior electrochemical properties. Nevertheless, it is difficult to commercialize sulfides due to their intrinsic properties such as dull reaction kinetics and an insufficient number of active sites. Herein, a self-supporting porous NiCoMnS sulfide (NiCoMnS/NF) arrayed on nickel foam (NF) with 3D honeycomb-like structure was designed and prepared via a hydrothermal and post-sulfidation process. It was found that the 3D hierarchically network architecture, constructed by nanosheets with abundant cavities, endowed NiCoMnS/NF with a high specific area and rich ion/electron-transport channels, which facilitated ion/electron transfer and Faradaic reaction kinetic. The optimal NiCoMnS/NF exhibited a markedly improved electrochemical performance due to the merits of complementary multi-composition and unique 3D network structure with multi-level "superhighways". Furthermore, the NiCoMnS//AC device fabricated with NiCoMnS/NF cathode and activated carbon (AC) anode delivered an excellent specific charge and exceptional energy density. This work offers a reference for designing the structure of electrode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell NiC 2 O 4 @C/N-doped NiCoZn-LDH(NCO@C/N-LDH) structure was prepared by two-step hydrothermal process. • Carbon and nitride were directly doped into NiCoZn-LDH nanosheets as shell. • The assembled NCO@C/N-LDH//AC devices provided high energy storage capability. Layered double hydroxides (LDHs) are promising cathode materials for supercapacitors due to high theoretical specific capacitance and unique layered structure. Constructing hierarchical core–shell structure for the multicomponent LDHs is an effective strategy to further utilize them. Herein, a novel hierarchical core–shell structure (NCO@C/N-LDH) was fabricated by direct-doping of C and N species into NiCoZn-LDH nanosheets (C/N-LDH) coved on NiC 2 O 4 (NCO) arranged on the nickel foam via two-step hydrothermal method. The NCO as a backbone prevented C/N-LDH nanosheets from collapsing in charge/discharge process, while the C/N-LDH shell provided abundant active sites and exclusive access to electron/ion transport for accelerating the Faradaic reaction kinetics. The optimal NCO@C/N-LDH (2.0) displayed a remarkable electrochemical performance with a high specific charge of 1841.0C/g at 1 A/g and good rate capability. Furthermore, the as-fabricated NCO@C/N-LDH//AC device delivered a high energy density of 56.9 Wh kg−1 at power density of 800 W kg−1. [ABSTRACT FROM AUTHOR]

A facile two-step hydrothermal approach with post-sulfurization treatment was put forward to construct the mixed transition metal sulfide (NiCoZnS) with a high electrochemical performance. The different morphologies of NiCoZnS materials were successfully fabricated by adjusted the Ni/Co molar ratio of the NiCoZn(OH)F precursor. Moreover, the in situ phase transformation from the NiCoZn(OH)F phase to Zn0.76Co0.24S and NiCo2S4 phases and lattice defects via the S2âˆ' ion-exchange were determined by x-ray diffractometer, transmission electron microscopy and x-ray photoelectron spectroscopy techniques, which improved electric conductivity and interfacial active sites of the NiCoZnS, and so promoted the reaction kinetics. Significantly, the urchin-like NiCoZnS1/1 prepared at the Ni/Co molar ratio of 1.0 exhibited promising electrochemical performances with high capacitance and excellent cycling stability. Furthermore, the asymmetric device (NiCoZnS//AC) using NiCoZnS1/1 as the positive electrode had excellent supercapacitor performances with an energy density of 57.8 Wh·kgâ€"1 at a power density of 750 W·kgâ€"1 as well as a long cycle life (79.2% capacity retention after 10 000 cycles), indicating the potential application in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDH) are regarded as promising electrode materials for supercapacitors due to their abundance, multiple oxidation states, and high theoretical capacitance. However, the limited active sites and dull reaction kinetics restrict their commercialization. In this work, the 3D hierarchical N-doping ZnCo-LDH array on nickel foam (NF) as an electrode material (N-ZnCo-LDH) was designed and directly fabricated via a hydrothermal method using 2-Methylimidazole as a nitrogen source. Consequently, the N-doping confined the growth of the N-ZnCo-LDH to form ultrathin nanosheets, which exposed more redox reaction active sites and facilitated the charge transfer, resulting in the enhancement in charge storage capacity. As a result, the optimal N (0.5) -ZnCo-LDH achieved a high specific charge of 942.6 C g−1 at 1.0 A g−1, excellent charge-discharge rate property (68.9% retention) and long durability (84.1% after 5 000 cycles). Also, the hybrid supercapacitor (N-ZnCo-LDH//AC) was fabricated employing N (0.5) -ZnCo-LDH as anode and activated carbon (AC) as cathode, which achieved an energy density of 29.2 Wh kg−1 at a power density of 750.0 W kg−1, and excellent cycling stability (84.0% retention after 10,000 cycles), which highlighted the potential of the N (0.5) -ZnCo-LDH electrode material towards practical application of supercapacitors. [Display omitted] • The ultrathin N-doped ZnCo-LDH nanosheets were synthesized using 2-Methylimidazole as nitrogen source. • N-doping confined the growth of the nanosheets, making them smaller and thinner. [ABSTRACT FROM AUTHOR]

• Se vacancy-rich NiMoSe nanowire skeleton was constructed on NF. • NiAl-LDH nanosheets were grown around the nimose skeletons to form core-shell structure. • NiMoSe@LDH cathode had high specific capacity of 1381.1 C g −1. • NiMoSe@LDH//AC delivered the energy density of 50.2 wh kg−1 at 800 w kg−1. As promising electrode materials, transition metal selenides show great potential applications in energy storage devices. Here self-supported Ni 0.85 Se nanowires with Se vacancies (denoted as NiMoSe) on NF were synthesized by a solvothermal route and post-selenization using NiMoO 4 as the precursor, which electrochemical performance was optimized by adjusting the Se feeding during the selenization. Whereas, the supercapacitive properties of the optimal NiMoSe need to be further improved for achieving higher rate capability and electrochemical stability. So, an efficient strategy was proposed to improve the electrochemical performance through welding the NiAl hydrotalcite (NiAl-LDH) nanosheets on the NiMoSe surface to construct a novel 1D-2D-3D hierarchical core-shell material (NiMoSe@LDH), which provided more active sites and ensured a high rate-capability and long-term stability. Benefiting from the synergistic effect between NiMoSe nanowires core and NiAl-LDH shell, the NiMoSe@LDH delivered a favorable specific charge of 1381.1 C g −1 at 1 A g −1 with impressive rate capability and cyclic stability (85.2% retention after 5 000 cycles at 5 A g −1). Furthermore, the as-assembled NiMoSe@LDH//AC afforded a high energy density of 50.2 Wh kg–1 at a power density of 800 W kg–1 and good cycling stability (86.5% retention at 5 A g −1 after 10 000 cycles) compared to the NiMoSe//AC (36.3 Wh kg–1 at 800 W kg–1, 77.3% retention). This work provides a new strategy for the design of high-performance transition metal selenides in next-generation energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

A core‐shell NiAlO@polypyrrole composite (NiAlO@PPy) with a 3D "sand rose"‐like morphology was prepared via a facile in situ oxidative polymerization of pyrrole monomer, where the role of PPy coating thickness was investigated for high‐performance supercapacitors. Microstructure analyses indicated that the PPy was successfully coated onto the NiAlO surface to form a core‐shell structure. The NiAlO@PPy exhibited a better electrochemical performance than pure NiAlO, and the moderate thickness of the PPy shell layer was beneficial for expediting the electron transfer in the redox reaction. It was found that the NiAlO@PPy5 prepared at 5.0 mL L−1 addition amount of pyrrole monomer demonstrated the best electrochemical performance with a high specific capacitance of 883.2 F g−1 at a current density of 1 A g−1 and excellent capacitance retention of 91.82 % of its initial capacitance after 1000 cycles at 3 A g−1. The outstanding electrochemical performance of NiAlO@PPy5 were due to the synergistic effect of NiAlO and PPy, where the uniform network‐like PPy shell with the optimal thickness made electrolyte ions more easily accessible for faradic reactions. This work provided a simple approach for designing organic–inorganic core‐shell materials as high‐performance electrode materials for electrochemical supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract To overcome the structural instability of polyaniline (PANI) due to repeated volumetric swelling and shrinking during charge/discharge process, the LDH/PANI composite was designed and prepared via the assembly of organic PANI and 2D host nanosheets from the MgFe layered double hydroxide (MgFe-LDH) through incorporation of PANI between the nanosheets gap using in situ polymerization. Owing to the combined advantages of conducting PANI and 2D nanosheets, the LDH/PANI composite exhibited excellent supercapacitive performance, including low resistance, high specific capacitance, good charge/discharge stability and long-term cycling life, which greatly improved faradaic redox reaction and mass transfer. As electrode material for supercapacitors, the LDH/PANI composite showed a maximum specific capacitance of 592.5 F·g−1 at a current density of 2 A·g−1, and achieved remarkable capacitance retentions of 87% after 500 cycles. The LDH/PANI material may be a potential economical alternative electrode material for supercapacitors. Highlights • The LDH/PANI composite was synthesized by intercalating PANI chains into the interlayers of the LDH. • The strong interaction between the PANI and LDH improved electrical conductivity of the LDH/PANI composite. • The LDH/PANI composite exhibited excellent supercapacitor performance. [ABSTRACT FROM AUTHOR]

A novel hierarchical 3D core-shell material [NF@NiCo 2 O 4 @NiCoMn(OH)] were fabricated for supercapacitors, in which the ultrathin NiCoMn(OH) nanosheets were coated on the NiCo 2 O 4 nanoarray supported on Ni foam. At the optimal Co-doping (Co/Ni molar ratio = 1: 5 at (Co+Ni)/Mn molar ratio of 4.0), the NiCoMn(OH) 1/5 had better rate capability and higher specific capacitance than the NiMn(OH) precursor, which improved the electrochemical properties. To further enhance the electrochemical performance, the NF@NiCo 2 O 4 @NiCoMn(OH) core-shell material was designed and prepared, which exhibited a much higher specific capacitance of 2300 F·g−1 than the NiCoMn(OH) 1/5 (1417 F·g−1) at 1 A∙g−1 and 87.7% retention at 5 A∙g−1 for 2 000 cycles. The excellent capacitive properties were ascribed to the unique 3D hierarchical structure and strong synergistic effect between the ultrathin NiCoMn(OH) nanosheets shell and NF@NiCo 2 O 4 nanoarray core. As a result of the asymmetric supercapacitor, the NiCo 2 O 4 @NiCoMn(OH)//AC device showed a remarkably high energy density (61.3 Wh∙kg−1) at a power density of 850 W∙kg−1. The strategy can be extended to other core-shell electrode material toward energy storage applications. [Display omitted] • The hierarchical 3D NF@NiCo 2 O 4 @NiCoMn(OH) core-shell material was synthesized via a facile two-step hydrothermal method. • The electrochemical performance was related to the Co-doping amount in the Co-free NiMn(OH) precursor. • The NF@NiCo 2 O 4 @NiCoMn(OH) core-shell material exhibited an excellent electrochemical property. • The strong synergistic effect and the unique 3D structure improved the electrochemical performances. [ABSTRACT FROM AUTHOR]

• The CuCo2S4 nanotube array on Ni foam was prepared by controlled the sulfurization time. • The crystallinity, morphology and electrochemical performance depend on the sulfurization time. • The optimal CuCo2S4/NF8 exhibited excellent electrochemical performances and good cycling stability. • The assembled CuCo2S4/NF8//AC device showed a high energy density 51.8 Wh kg 1 at a 700 W kg 1. The CuCo 2 S 4 sulfides were fabricated on Ni foam (NF) through a single-step hydrothermal deposition followed by sulfurization at different times. The results from various spectroscopic and microscopic analyses showed that the 3D hollow nanotube CuCo 2 S 4 arrays were formed by the sulfurization, resulting in a larger contact area with the electrolyte and more active sites with high Faraday efficiency. Benefited from the unique nanotube arrays structure and high crystallinity, the optimized CuCo 2 S 4 /NF 8 electrode material sulfurized for 8 h displayed superior electrochemical performances with the high specific charge of 458.8 C g −1 at 1.0 A g −1 as well as good cycling stability with 96.0% retention at 5.0 A g −1 after 1 000 cycles. Furthermore, a hybrid supercapacitor device based on the CuCo 2 S 4 /NF 8 as positive electrode and activated carbon as negative electrode was able to deliver an ultrahigh energy density 51.8 Wh kg−1 at a power density 700.0 W kg−1 with 80.0% capacitance retention at 5.0 A g −1 after 10 000 cycles. This work provided new insights into the sulfurization process and an effective way to optimize the structure of the transition metal sulfides for supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

The pineapple flower-like hierarchical Co 3 O 4 @CoAl-layered double hydroxides (Co 3 O 4 @ CoAl-LDH) with 3D mesoporous network structure were designed and in-situ synthesized on nickel foam (NF) through a facile two-step hydrothermal route for supercapacitors. The Co 3 O 4 @CoAl-LDH displayed a greater specific capacitance of 949.7C g−1 (1899.4 F g−1) at 1.0 A g−1, better rate capability and higher cycle stability comparing with the pristine Co 3 O 4 and CoAl-LDH on NF. At the same time, the as-fabricated Co 3 O 4 @CoAl-LDH//activated carbon (Co 3 O 4 @CoAl-LDH//AC) device delivered outstanding energy densities of 77.58 and 36.03 Wh kg−1 at a power density of 754.83 and 7813.73 W kg−1, respectively, and excellent rate capability and outstanding long-term cycle stability (84.99% retention of the initial value at 5 A g−1 after 20,000 cycles). The superior electrochemical performances showed that the Co 3 O 4 @CoAl-LDH was a promising candidate as electrode materials for high-performance energy storage devices. [Display omitted] • The hierarchical Co 3 O 4 @LDH grown on nickel foam was successfully prepared. • The Co 3 O 4 @LDH exhibited a high specific capacitance. • The assembled Co 3 O 4 @ LDH//AC device showed excellent performances. [ABSTRACT FROM AUTHOR]

The hierarchical core-shell structure CuCo 2 S 4 @NiCoAl-LDH/NF composite with 3D mesoporous network structure was designed and prepared, where the NiCoAl hydrotalcite (NiCoAl-LDH) was as shell, and the CuCo 2 S 4 nanotube array on Ni foam (NF) as core. Owing to the unique architecture and integration of respective merits from each component, the core-shell material displayed a large surface area, high conductivity, short ion diffusion path and rapid interfacial charge transmission. So, the CuCo 2 S 4 @NiCoAl-LDH/NF electrode showed superior electrochemical performances with a high specific capacitance of 938C g−1 (1876 F g−1) at 1.0 A g−1 and excellent cycling stability (retention of 91.11% after 5000 cycles at 5 A g−1). The eminent performances suggested that the CuCo 2 S 4 @NiCoAl-LDH/NF with 3D mesoporous network core-shell structure was one of the candidates as electrodes for high-performance supercapacitors. Unlabelled Image • CuCo 2 S 4 @NiCoAl-LDH composite with 3D mesoporous network structure and tunable component was prepared. • CuCo 2 S 4 nanotubes array on Ni foam were as supporting core and NiCoAl-LDH nanosheets with 3D honeycomb porous network as shell. • The as-prepared composite exhibited a high specific capacitance of 937.5C g−1 and satisfactory cycling stability. [ABSTRACT FROM AUTHOR]

To reduce the charge‐transfer resistance of supercapacitors and achieve faster reversible redox reactions, ternary Ni‐Co‐Fe layered double hydroxide was prepared by using the urea method and then calcined to give NiCoFe oxide (NiCoFeO). To enhance conductivity, a polyaniline (PANI) conductive layer was assembled on the surface of the NiCoFeO particles by in situ oxidative polymerization of aniline monomers. The as‐prepared NiCoFeO/PANI composite was successful employed as a supercapacitor electrode. It was found that the NiCoFeO/PANI composite displayed good cycling stability, with a capacity loss of only 29.54 % after 5000 cycles. Furthermore, the NiCoFeO/PANI composite also exhibited excellent supercapacitor performance, with a high specific capacity of 843 F g−1 at a current density of 2 A g−1, whereas NiCoFeO showed a specific capacity of only 478 F g−1. This result was attributed to the synergistic effect between NiCoFeO and PANI. The facile synthesis strategy and excellent electrochemical performance suggest that NiCoFeO/PANI is a promising economical electrode material for applications in supercapacitors. Composites for supercapacitors: A novel NiCoFeO/polyaniline (PANI) composite was fabricated by in‐situ oxidative polymerization and applied as an electrode material for supercapacitors. The composite displayed excellent supercapacitor performance with a high specific capacity of 843 F g−1 at a current density of 2 A g−1 and good cycling stability, with a capacity loss of only 29.54 % after 5000 cycles (see figure). [ABSTRACT FROM AUTHOR]

The synthesis and capacitance performance of flexible Manganese dioxide (MnO 2 )/carbon nanotube (CNTs) composite films were systematically studied in this paper. Firstly, MnO 2 nanosheets were successfully deposited onto the CNTs paper via a self-controlled redox process in KMnO 4 solution. The nanostructured MnO 2 /CNTs composite films with hierarchical porous structure could be directly fabricated as supercapacitor electrodes without binder or conductive agents. The crystalline and morphology properties of composites were studied by X-ray diffraction, Raman scattering, Scanning electron microscope and Transmission electron microscope. By electrochemical measurement of the as-fabricated flexible supercapacitor electrode, it achieved the area specific capacitance of 1980 F/m 2 with the good capacitance retention of 87% over 3000 cycles at a current density of 10 A/m 2 . The enhanced electrochemical properties could be ascribed to the porous architecture for fast ion diffusion, the conductive CNTs paper and the controlled morphology. Moreover, the symmetric supercapacitor delivered an energy density of 177 Wh/m 2 at a power density of 250 W/m 2 and maintained an energy density of 138 Wh/m 2 at a power density of 5 kW/m 2 . The research in this paper suggested that this ultralight and flexible electrode could be the promising candidates for wearable energy storage devices. [ABSTRACT FROM AUTHOR]