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As one of the energy storage devices, supercapacitors (SCs) have the advantages of high-power density, short charging time and excellent cycle stability, and have received widespread attention. Therefore, designing and synthesizing a supercapacitor material with high energy density has become a key factor to promote the development of SCs. In this work, the inter-crosslinked Co 3 S 4 nanosheets which derived from ZIF-67 are successfully loaded on Co 2 (CO 3)(OH) 2 nanowires (CoCH NWs) can significantly facilitate the diffusion of electrolyte ions and enhance mass/electron transfer. The obtained Co 3 S 4 @CoCH composite grows directly on nickel foam (NF) substrates without binder, which improves the conductivity of Co 3 S 4 @CoCH/NF electrode. Consequently, the obtained Co 3 S 4 @CoCH/NF electrode possesses an excellent capacitance of 2697.1 F g−1 at 2 A g−1 and outstanding rate capability (84.4 % retention at 2–20 A g−1). In the three-electrode system, the capacitance retention is 79.8 % after 8000 cycles at a current density of 10 A g−1. An asymmetric supercapacitor assembled from Co 3 S 4 @CoCH/NF and activated carbon as cathode and anode respectively which has fabulous energy density of 42.2 W h kg−1 at 799.0 W kg−1 and stability (74.0 % retention after 8000 cycles). It improves that Co 3 S 4 @CoCH/NF is a promising cathode material for supercapacitors. • Co 3 S 4 are anchored on Co 2 (CO 3)(OH) 2 nanowires (CoCH NWs) to form composites and supported on foamed nickel. • Co 3 S 4 @CoCH/NF has excellent specific capacitance and outstanding rate capability. • The introduction of CoCH NWs improves the structure of Co 3 S 4 nanosheet. • Asymmetric supercapacitor Co 3 S 4 @CoCH/NF//AC (activated carbon) exhibits great performance. [ABSTRACT FROM AUTHOR]

Supercapacitors with long life and high power density can be used in power tools and wind power equipment. However, increasing energy density without sacrificing advantages remains a major challenge, which limits their practical application. Therefore, efforts have been made to manufacture supercapacitors with high capacitance and long life. Ce-doped SnS micron flowers grown on nickel foam (Ce@SnS/NF) have been synthesized using a facile solvothermal method. The effect of Ce doping on the SnS, where Ce doping confined the growth of Ce@SnS to form smaller nanosheets and provided more active sites, resulting in the enhancement of the capacity and cycle stability, has been explored. In a three-electrode system, the specific capacitance increased from 1237 F/g (171.8 mAh/g) to 2549 F/g (354.0 mAh/g) at 2 A/g, and the stability was 85.5 % after 10,000 cycles at 10 A/g. A hybrid supercapacitor (Ce@SnS/NF (+)//AC (–)) assembled from Ce@SnS/NF and activated carbon as cathode and anode, respectively. The device has an energy density of 48.83 Wh/kg at 824.91 W/kg and long cycle stability (91.6 % retention after 20,000 cycles at 5 A/g). Moreover, the supercapacitor can power a white light-emitting diode (LED) for 15 min, so the Ce-doped SnS cathode has vast application prospects in supercapacitors. [Display omitted] • SnS grows firmly on nickel foam by a solvothermal method. • Cerium doping improves the capacitance of SnS from 1237 F/g to 2549 F/g. • Cerium doping increases the cycle life of SnS from 77.6 % to 88.5 %. • Kinetics explains the enhanced performance of Ce@SnS/NF. • The device Ce@SnS/NF//AC has a long cycle life of 91.6 % retention. [ABSTRACT FROM AUTHOR]

Flower-like β-Ni(OH) 2 encapsulated by flexible reduced graphene oxide (rGO) nanosheets have been synthesized by one-pot hydrothermal process and were used as Faradaic electrodes for supercapacitors. β-Ni(OH) 2 microflowers whose particle sizes ranging from 1.7 to 2.5 μm were effectively encapsulated by flexible rGO nanosheets. Due to the efficient charge transfer and unimpeded ion transports, such β-Ni(OH) 2 /rGO composites can deliver ultrahigh specific capacity of 618 C g −1 at a current density of 3 A g −1 and maintain 276 C g −1 at 30 A g −1 in 6 M KOH electrolyte. Besides, the β-Ni(OH) 2 /rGO composite electrode exhibits outstanding cyclic stability. When tested at a current density of 10 A g −1 , high capacity retention ratio up to 90% can be achieved for the composite electrode after 2000 cycles. The outstanding cycling stability can be mainly attributed to rGO-encapsulating structure that effectively prevent the descent of electrical conductivity for the entirety of the electrode during the cycle processes. The ultrahigh specific capacity together with superb cycle performance make such composite a prospective candidate in capacitive energy storage field. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) porous structure that designed based on MnCo 2 O 4 decorated graphene was synthesized by a two-step method. The precursor was prepared of MnCo 2 O 4 by solid phase synthesis method, then in the hydrothermal reaction course, the graphene nanosheets as well as this precursor were self-assembled into a 3D interconnected network. The resultant composite materials present a higher specific capacitance (503 F g−1 at 1 A g−1 current density) and an excellent cycling stability. After 5000 charge/discharge cycles at a current density of 10 A g−1, 97.4% of the specific capacitance was retained. Thus, this material has a promising application potential for supercapacitor, at the same time, this synthetic method can also provide an idea for synthesizing composites based on 3D graphene in the future. • Three-dimensional composites of MnCo 2 O 4 and graphene were synthesized. • Three-dimensional graphene provides a porous skeleton. • The MnCo 2 O 4 /3DG electrode exhibits excellent electrochemical properties. • The excellent supercapacitor performance is attributed to the synergistic effect. [ABSTRACT FROM AUTHOR]

The porous urchin-like and flower-like NiCo 2 O 4 microspheres have been synthesized by a mild hydrothermal method combined with a simple annealing treatment. With the addition of sodium dodecyl sulfate (SDS), the morphology of NiCo 2 O 4 microspheres changes from the urchin-like to the flower-like. The flower-like NiCo 2 O 4 microspheres（NCO-5）with a larger specific surface area of 158 m 2 /g constructed by interconnected nanosheets exhibit a higher specific capacitance of 1538 F/g at 10 A/g and an excellent cycling stability. When the current density is 10 A/g, high capacity retention ratio up to 92.3% can be achieved for the flower-like NiCo 2 O 4 microspheres electrode after 2500 cycles. The enhanced electrochemical performance can be mainly attributed to the hierarchical porous framework with a large specific surface area. Therefore, the remarkable capacitive performance of the flower-like NiCo 2 O 4 microspheres will undoubtedly make them more attractive for high performance supercapacitors. [ABSTRACT FROM AUTHOR]

• This article applied a facile method to introduce oxygen vacancies into MgCo 2 O 4 as electrode of supercapacitor. • the capacitance of OV-MgCo 2 O 4 was improved by 33% compared with pristine MgCo 2 O 4. • It explains the enhanced capacity of OV-MgCo 2 O 4 from kinetics. • A coin cell which assembled using OV-MgCo 2 O 4 and active carbon exhibits great electrochemical performance. Here, we report a facile strategy to synthesize MgCo 2 O 4 with abundant oxygen vacancies (OV-MgCo 2 O 4) using for the electrode materials of asymmetric supercapacitors (ACS). Benefiting from the NaBH 4 reduction treatment to offer oxygen vacancies, the specific capacitance of OV-MgCo 2 O 4 was improved to 460 F g−1 (1 A g−1), much higher than untreated MgCo 2 O 4 (340 F g−1 at 1 A g−1). We fabricated OV-MgCo 2 O 4 //AC ACS device to investigate the further application of OV-MgCo 2 O 4. This hybrid ACS exhibits excellent specific capacity of 52.5 F g−1 (0.4 A g−1), with a great energy density of 18.7 Wh kg−1 (320 W kg−1). Our work demonstrates the important role of oxygen vacancies in improving the capacity of metal oxides. [ABSTRACT FROM AUTHOR]