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A honeycomb-like structure nanocomposite composed of Ag nanoparticles doped NiMn-LDHs nanosheets shell and uniformly arranged Co 2 (OH) 2 CO 3 nanoneedles core shows promising electrochemical storage properties. [Display omitted] • Honeycomb-like CC@Co 2 CH/NM-LDH-Ag nanosheet arrays are synthesized on carbon cloth. • The hybrid of various active components provides abundant active sites and fast ion diffusion. • CC@Co 2 CH/NM-LDH-Ag is used to prepare binder-free electrodes and exhibits excellent electrochemical properties. • The assembled all-solid-state asymmetric supercapacitor shows high energy density and power density. Layered double hydroxides are considered promising electrode materials for the preparation of high-energy–density supercapacitors owing to their suitable microstructure and significant electrochemical properties. In this study, honeycomb-like NiMn-layered double-hydroxide (NiMn-LDH) nanosheet arrays with numerous electron/ion channels, a large number of active sites, considerable redox reversibility, and significant electrical conductivity were synthesized by combining Co 2 (OH) 2 CO 3 nanoneedle arrays with NiMn-LDH nanosheet arrays and Ag nanoparticles on a carbon cloth (CC) substrate through a hydrothermal strategy (CC@Co 2 CH/NM-LDH-Ag). The fabricated CC@Co 2 CH/NM-LDH-Ag binder-free electrode exhibited a high specific capacitance of 10,976 mF cm−2 (3092F/g, 1391.4C g−1) at 2 mA cm−2 (1 A/g), and a high capacitance retention of 93.2 % after 10,000 cycles at a current density of 20 mA cm−2. In addition, a solid-state asymmetric supercapacitor (ASC) device assembled using CC@Co 2 CH/NM-LDH-Ag as the cathode possessed an ultrahigh energy density of 68.85 Wh kg−1 at a power density of 722.6 W kg−1, and two fabricated ASC units in series were able to power a multifunctional display for more than 30 min. Therefore, this study provides a new approach for the design and synthesis of high-performance flexible electrodes. [ABSTRACT FROM AUTHOR]

Origami and layered-shaped ZnNiFe-LDH synthesized on Cu(OH) 2 nanorods array to enhance the energy storage capability. [Display omitted] The combination of layered nanorod arrays with unique core–shell structure and transition metal layered double hydroxide (LDH) is considered as a feasible solution to improve the electrochemical performances of capacitor electrode. In this study, layered ZnNiFe-LDH@Cu(OH) 2 /CF core–shell nanorod arrays, which consist of ultrathin ZnNiFe-LDHs nanosheet shells and ordered Cu(OH) 2 nanorod inner cores, are successfully designed and fabricated by a typical hydrothermal way and a simple in situ oxidation reaction. The electrode prepared using ZnNiFe-LDH@Cu(OH) 2 /CF nanomaterial reveals an remarkable area capacitance of 6100 mF cm−2 at 3 mA cm−2 current density, which is excellently superior than those of ZnFe-LDH@Cu(OH) 2 /CF, NiFe-LDH@Cu(OH) 2 /CF, Cu(OH) 2 /CF and CF. Additionally, the capacitance retention remains as high as 83.4% after 5000 cycles and a very small Rs (0.567 Ω) can be observed. In addition, an asymmetric supercapacitor device is successfully fabricated employing ZnNiFe-LDH@Cu(OH) 2 /CF. Meanwhile, the ZnNiFe-LDH@Cu(OH) 2 /CF//AC device can achieve an energy density of 44 Wh kg−1 and a corresponding power density of 720 W kg−1 and possess the capability to light up a multi-function monitor for 33 min just using two ASC equipments connected in series. Therefore, the prepared ZnNiFe-LDH@Cu(OH) 2 /CF composite materials with unique structure has great application potential in energy storage devices. [ABSTRACT FROM AUTHOR]

Laminated and scale-like Ni/Zn-MOF/ZnO@CC hybrid materials with high orientation are synthesized and exhibit promising electrochemical properties. [Display omitted] Metal-organic frameworks (MOFs) are attracting tremendous research interest because of their rich redox sites and high specific area which are beneficial for the energy storage applications. Nevertheless, the poor conductivity, low mechanical strength and unsatisfactory capacity severely hinder their wide application. Hence, it is of practical significance to design highly efficient and facile strategy to solve these issues. Herein, vertically oriented ZnO nanorod arrays are applied as precursor to synthesize laminated scale-like and highly-oriented Ni/Zn-MOF/ZnO nanocomposite. Owing to the desirable conductivity resulting from the doping nickel ions and the interaction between ZnO and its relative MOF, the fabricated 0.3Ni/Zn-MOF/ZnO@CC electrode exhibits an electrochemical capacitance of 1693 mF cm−2 at 1 mA cm−2. Moreover, the electrochemical capacitance retention of 80.7 % after 2500 cycling numbers is obtained under the constant current density of 10 mA cm−2 and the low internal resistance R s of 0.89 Ω is observed. For practical application, the as-synthesized laminated scale-like Ni/Zn-MOF/ZnO@CC nanocomposite is served as positive electrode to fabricate solid-state asymmetric supercapacitor device. Moreover, a 2.5 V indicator could be powered for 8 min when the prepared supercapacitor units are connected. This work demonstrates the promising potential of the synthesized scale-like Ni/Zn-MOF composites for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

Hierarchical CoSe 2 @NiMn-LDH@Cu 1.8 Se/CF nanosheet arrays with core-shell structure are synthesized via phase pseudomorphic transformation process achieved by selective selenization for Cu and Co elements for green chemistry energy storage. [Display omitted] As an emerging energy storage device, the practical application of supercapacitors (SCs) is currently constrained by their low energy density. Enhancing the capacitance of supercapacitors by leveraging the synergistic effect of multiple components in composite electrodes with well-designed structures can effectively increase their energy density. Here, a wire-sheet-particle hierarchical heterostructured CoSe 2 @NiMn-layered double hydroxide (NiMn-LDH) @Cu 1.8 Se/Copper foam (CF) electrode is synthesized via phase pseudomorphic transformation process achieved by selective selenization for Cu and Co elements. Benefiting from the stable support structure of CuBr 2 , the large specific surface area of NiMn-LDH, and the excellent conductivity of CoSe 2 , the prepared binder-free electrode shows excellent electrochemical properties. The CoSe 2 @NiMn-LDH@Cu 1.8 Se hybrid electrode exhibits a superior specific areal capacitance of 7064 mF cm−2 at 2 mA cm−2 and a stable cyclic performance with 80.11 % capacitance retention after 10,000 cycles. Furthermore, the assembled CoSe 2 @NiMn-LDH@Cu 1.8 Se/CF//AC (activated carbon) asymmetric supercapacitor (ASC) achieves an energy density of 36.6 Wh kg−1 when the power density is 760.6 W Kg−1 and retains 87.35 % of the initial capacitance after 5000 cycles. Overall, this pioneering research provided new insight for preparing supercapacitor electrode materials by selective selenization and ration design of the structures. [ABSTRACT FROM AUTHOR]