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Supercapattery is an ideal energy storage device combining the features of supercapacitors and batteries, offers a high‐energy density as well as high‐power density with extended operational lifespan. In this work, zinc sulfide (ZnS) and zinc sulfide/nickel oxide (ZnS/NiO) nanocomposite was synthesized via chemical coprecipitation method and characterized using state‐of‐the‐art analytical tools. The ZnS/NiO electrode exhibited remarkable electrochemical performance as an electrode material than pure ZnS. The ZnS/NiO nanocomposite exhibited high crystallinity, and spherical nanoparticles with an average grain size of 20–40 nm having a homogeneous dispersion. The ZnS/NiO electrode exhibited an ultrahigh specific capacity of 1803.87 Cg−1 at a relatively low scan rate of 10 mVs−1 in a 1 M KOH solution from cyclic voltammetry and 393 Cg−1 at 16 Ag−1 from charge discharge measurements, and it showed exceptional cycling stability (98 % capacity retention after 1000 cycles). Furthermore, the ZnS/NiO symmetric supercapattery device exhibited 44.43 Fg−1 specific capacitance, 5.52 Wh kg−1 energy density, and 1600 Wkg−1 power density at current density of 0.8 Ag−1 in 1 M KOH solution from galvanostatic charge discharge. After 3000 cycles, the ZnS/NiO nanomaterial demonstrated promising cyclic stability of 95 %. The ZnS/NiO supercapattery nanocomposite might be considered as a potential hybrid electrode material for the future development of electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

Supercapacitor (SC) devices holds an important position between traditional capacitors and ion batteries in terms of energy density and power density values. In particular, SC′s greater power density values than Li‐ion batteries make them useful for some specific applications, such as storing energy in hybrid cars while the car slows down. Increasing energy density values is one of the key challenges for the SC community. Transition metal dichalcogenides (TMDCs), are one of the new developing important material systems to have this potential, compared to their counterparts' transition metal oxides and conductive polymers. This review is about giving insight into the electrochemical performances of two‐dimensional (2D) layered transition metal sulfides (TMS) such as MoS2, WS2, TaS2, NbS2, VS2, TiS2 and ZrS2 materials. On the other hand, the methods mostly used in synthesizing these materials are presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • PBA@CCH nanocubes are successfully constructed via an in-situ epitaxial growth strategy. • The morphology and structure of the coating can be modulated by varying the composition of reaction reagents. • The formation mechanism of the coating with variable morphology are discussed and analyzed in detail. • The CoNi2S4/Co9S8@Co4S3 heterogeneous nanocubes are fabricated via one-step carbonization and sulfidation method. Construction of Prussian blue analogues (PBAs) with heterostructure is beneficial to preparing PBAs derivatives with superior electrochemical performance. In this work, the core–shell nanostructured nanocubes composed of nickel hexacyanocobalt PBA (NiCo-PBA)@cobalt carbonate hydroxide (CCH) are synthesized through an in-situ epitaxial growth strategy, and the formation mechanisms of coating are carefully validated and specifically discussed. Then, the precursors are successfully transformed into hierarchical CoNi 2 S 4 /Co 9 S 8 @Co 4 S 3 via the gas-phase vulcanization method. Benefiting from the intriguing heterostructure and multicomponent sulfides, the CoNi 2 S 4 /Co 9 S 8 @Co 4 S 3 -80 electrode exhibits a high specific capacity of 799 ± 16C/g (specific capacitance of 1595 ± 31F/g) at 1 A/g, ultra-high capacity retention of 80 % at a high current density of 20 A/g. The assembled asymmetric supercapacitor (ASC) device delivers a high energy density of 43.3 Wh kg−1 at a power density of 899 W kg−1 and exhibits superior cycling stability with the capacity retention of 88 % after 5,000 cycles. Subsequently, the fabricated all-solid-state ASC device shows an excellent energy density of 36.4 Wh kg−1 with a power density of 824 W kg−1. This work proposing rational design of combining multicomponent sulfides and core–shell heterostructure based on PBA nanocubes opens up a novel route for developing asymmetric supercapacitor electrode materials with superior performance. [ABSTRACT FROM AUTHOR]

Cobalt sulfides are considered as promising candidates for lithium-ion battery (LIB) anode materials with high energy densities. Their energy storage mechanism is widely understood to involve the traditional intercalation and conversion reaction. However, these conventional mechanisms are unable to explain the storage capacities of certain materials which exceed the theoretical limit. Here, utilizing advanced in situ magnetometry to detect the magnetization evolution of Co1-x S LIBs in real time, it is demonstrated that the Co-catalytic lithium storage process and interfacial space charge storage mechanism are strongly related to the additional capacity of cobalt sulfides. During discharge, a Co/Li2 S interface is formed, wherein the Co nanoparticles and Li2 S could store a large amount of polarized electrons Li+, respectively. Subsequently, the electrons stored in Co are transferred to the polymeric film, forming radical anions and contributing extra capacity. These findings reveal the charge storage mechanisms of transition metal sulfides and highlight the critical role of magnetic testing in the investigation of energy storage mechanisms. [ABSTRACT FROM AUTHOR]

At present, binary bimetallic sulfides are widely studied in supercapacitors due to their high conductivity and excellent specific capacitance (SC). In this article, NiCo-S nanostructured hybrid electrode materials were prepared on nickel foam (NF) by using a binary metal–organic skeleton as the sacrificial template via a two-step hydrothermal method. Comparative analysis was carried out with Ni-S and Co-S in situ on NF to verify the excellent electrochemical performance of bimetallic sulfide as an electrode material for supercapacitors. NiCo-S/NF exhibited an SC of 2081 F∙g−1 at 1 A∙g−1, significantly superior to Ni-S/NF (1520.8 F∙g−1 at 1 A∙g−1) and Co-S/NF (1427 F∙g−1 at 1 A∙g−1). In addition, the material demonstrated better rate performance and cycle stability, with a specific capacity retention rate of 58% at 10 A∙g−1 than at 1 A∙g−1, and 75.7% of capacity was retained after 5000 cycles. The hybrid supercapacitor assembled by NiCo-S//AC exhibited a high energy density of 25.58 Wh∙kg−1 at a power density of 400 W∙kg−1. [ABSTRACT FROM AUTHOR]

The intent of designing and exploring novel active electrode materials is to enhance the electrochemical performance of supercapacitors. Herein, a hierarchical structure of nickel-cobalt-sulfide nanostructures (NiCo 2 S 4) decorated on the electrospun N -doped carbon nanofiber (CNF), NiCo 2 S 4 @CNF, is manipulated using a one-step and simple hydrothermal approach. The fabricated hierarchical structure of the NiCo 2 S 4 @CNF is featured by a large surface area and a high porosity that serve as ion diffusion channels. Therefore, it manifests high specific capacitance and specific capacity values of 377.2 C g−1 and 754.4 F g−1 at a current density of 1 A g−1, respectively. Furthermore, a NiCo 2 S 4 @CNF//CNF hybrid supercapacitor in which a positive electrode of NiCo 2 S 4 @CNF is assembled with a negative electrode of CNF to estimate the electrochemical performance of the NiCo 2 S 4 @CNF. As a result, the device has a superior energy density of 65.6 and 52.5 Wh kg−1 at a power density of 665 and 1313.8 W kg−1, respectively. Moreover, the device reveals good stability with capacitance retention of 72% after 3000 charge/discharge cycles. These outstanding results enable the designed hierarchical structure of the NiCo 2 S 4 @CNF to be a promising electrode material for supercapacitors (SCs) applications. [Display omitted] • The hierarchical structure of NiCo 2 S 4 @CNF was prepared to be used as an efficient electrode for a hybrid supercapacitor. • NiCo 2 S 4 @the electrospun N -doped CNF has a higher surface area and a high porosity that serves as ion diffusion channels. • NiCo 2 S 4 @CNF hierarchical structure exhibited a specific capacitance of 754.4 F g−1 at a current density of 1 A g−1. • NiCo 2 S 4 @CNF//CNF hybrid supercapacitor showed specific energy of 65.6 W h kg−1 at a specific power of 665 W kg−1. [ABSTRACT FROM AUTHOR]

Rational designing of electrode materials is of great interest for improving the performance of battery-type supercapacitors. The bimetallic NiCo2S4 (NCS) and CoNi2S4 (CNS) electrode materials have received much attention for supercapacitors due to their rich electrochemical characteristics. However, the comparative electrochemical performances of NCS and CNS electrodes were never studied for supercapacitor application. In this work, microsphere-like bimetallic NCS and CNS structures were synthesized via a facile one-step hydrothermal method by controlling the molar ratio of Ni and Co precursors. The physico-chemical results confirmed that microsphere-like structures with cubic spinel-type NCS and CNS materials were successfully fabricated by this method. When tested as the supercapacitor electrode materials, both NCS and CNS electrodes exhibited battery-type behavior in a three-electrode configuration with outstanding electrochemical performances such as specific capacity, rate performance and cycle stability. Impressively, the CNS electrode delivered a high specific capacity of 430.1 C g−1 at 1 A g−1, which is higher than 345.9 C g−1 of the NCS electrode. Furthermore, the NCS and CNS electrodes showed a decent cycling stability with 75.70 and 84.70% capacity retention after 10,000 cycles. Benefiting from the electrochemical advantage of CNS microspheres, we fabricated a hybrid supercapacitor (HSC) device based on CNS microspheres (positive electrode) and activated carbon (AC, negative electrode), which is named as CNS//AC. The assembled CNS//AC HSC device showed a large energy density of 41.98 Wh kg−1 at a power density of 800.04 W kg−1 and displayed a remarkable cycling stability with a capacity retention of 91.79% after 15,000 cycles. These excellent electrochemical performances demonstrate that both bimetallic NCS and CNS microspheres may provide potential electrode materials for high performance battery-type supercapacitors. [ABSTRACT FROM AUTHOR]

Summary: In this study, stimulating approach electrodeposition has been espoused to fabricate binder‐free electrodes of transition metal sulfides to achieve high electrochemical performance for energy storage devices. Here, the effect of Co and Cu with MnS has been scrutinized by gradually replacing Co with Cu concentration. The fabricated electrodes have been examined by FESEM to analyze the structural morphology of the material. Furthermore, electrochemical characterizations have been carried out for exploring the electrode performance which reveals that the S4 electrode (Cu0.75Co0.25MnS) exhibits the best performance as compared to contender electrodes. This electrode exhibits a high specific capacitance of 4800 F/g at 10 A/g current density with a smaller ESR value of 0.48 Ω. Additionally, the S4 electrode has been used as a cathode and activated carbon (AC) as an anode in assembling of supercapacitor device. Device S4//AC portrayed a maximum energy density of 118 Wh/kg with a power density of 960 W/kg at 1.2 A/g. The obtained results prophesied that the electrochemical performance of metal sulfides has been intensified by varying the concentration of material for superior electrochemical applications. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) have become promising candidates as electrode materials in energy storage fields thanks to the high theoretical capacity. However, their application is hindered by depressed electrical conductivity and poor cycling performance. Herein, we proposed a ZIF-67 derived, nitrogen-doped, graphene-coated and carbon nanotubes-interlinked 3D Co 3 S 4 /C conductive network (N–Co 3 S 4 -GN/CNT) for high-performance supercapacitors. Through controlling the mass ratio of ZIF-67, melamine and g-C 3 N 4 , various microstructures with determined electrochemical performance could be achieved. The nanocomposites synthesized with the ingredient mass ratio of 2: 1: 1 (NCSC-211) were proven to have the most excellent comprehensive electrochemical properties. In the NCSC-211 nanostructure, multi-layer graphene function as conductive shells for improved cycling performance by alleviating pulverization caused by volume change, thick CNTs act as conductive bridges and agglomeration spacers that increase electron conductivity and provide more active sites for redox reaction and doped-nitrogen offer enhanced wettability to electrolyte and faster electron transfer. The NCSC-211 electrode displayed specific capacitance of 1158 F g−1 at 1 A g−1, rate capability of 86% at 10 A g−1 and extraordinary cycling stability with 97.2% capacitive retention after 4000 cycles. Furthermore, the assembled asymmetric supercapacitor NCSC-211//activated carbon exhibited energy density of 43.73/37.69 Wh kg−1 at power density of 800/8000 W kg−1 and capacity retention of 95.3% after 5000 cycles at 5 A g−1. The designing strategy of in-situ grown instead of additional added conductive phase that fully-covered and strongly-interlinked network nanostructure may pave the road towards TMSs in synthesizing energy storage materials by compensating their intrinsic drawbacks. The N–Co 3 S 4 -GN/CNT 3D interlinked conductive network nanostructures were rationally designed and successfully synthesized as electrode materials for supercapacitors. The NCSC-211 electrode exhibited the most comprehensive electrochemical performance especially long cycle life, which thanks to the in-situ grown multi-layer graphene shells as well as thick carbon nanotubes bridges and spacers. [Display omitted] • Construction of N–Co 3 S 4 -GN-CNT 3D interlinked conductive network nanostructure. • The graphene and carbon nanotubes are in-situ grown instead of additional synthesized and further composited. • Tightly-coated graphene conductive shells restrain volume expansion of Co 3 S 4 nanoparticles. • Strongly-interlinked CNTs conductive bridges and agglomeration spacers increase electrical conductivity and active sites. • Extraordinary cycling stability with 97.2% capacitance retention after 4000 cycles for cobalt sulfide electrode materials. [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]

Metal-organic frameworks (MOFs) as self-sacrificing templates for high-performance supercapacitor electrode materials have garnered significant attention. In this study, the core-shell multi-heterojunction array of NiCo-LDH@NiCoS@NiMnS was synthesized for the first time using a NiCo-MOF template through hydrothermal growth, followed by ion substitution etching and controlled sulfidation. The NiCo-LDH@NiCoS@NiMnS core-shell multi-heterojunction boasts a hierarchically porous framework, multi-component synergy, and robust structural stability, which together provide abundant redox active sites and facilitate rapid reaction kinetics. Consequently, the self-supporting NiCo-LDH@NiCoS@NiMnS porous electrode achieves a specific capacitance of 9.31 F cm−2 (1862 F g−1) at 8 mA cm−2 (1.6 A g−1) and demonstrates excellent rate performance (52 %, 8–50 mA cm−2). The assembled NiCo-LDH@NiCoS@NiMnS//AC asymmetric supercapacitor (ASC) exhibits an energy density of 88.9 Wh kg−1 at 323.5 W kg−1, maintaining an energy density of 49.7 Wh kg−1 even at a power density of 4043 W kg−1. It retains 90 % of its capacitance after 6000 cycles at 16 mA cm−1. Notably, two ASC devices in series can power an LED light for over 30 minutes. These results confirm that the MOF self-sacrificing template method and controllable sulfidation strategy are effective for designing electrode structures in electrochemical energy storage. [Display omitted] • The NiCo-LDH@NiCoS@NiMnS core-shell multiple heterojunctions array electrodes are synthesized. • The porous heterojunction framework shows good structural stability and fast reaction kinetics. • The synergistic effect between the multi-components improves the energy storage performance. • A hybrid supercapacitor delivers an energy of 49.7 Wh kg−1 at 4043 W kg−1. [ABSTRACT FROM AUTHOR]

Rational designing of electrode materials is of great interest for improving the performance of battery-type supercapacitors. The bimetallic NiCo2S4 (NCS) and CoNi2S4 (CNS) electrode materials have received much attention for supercapacitors due to their rich electrochemical characteristics. However, the comparative electrochemical performances of NCS and CNS electrodes were never studied for supercapacitor application. In this work, microsphere-like bimetallic NCS and CNS structures were synthesized via a facile one-step hydrothermal method by controlling the molar ratio of Ni and Co precursors. The physico-chemical results confirmed that microsphere-like structures with cubic spinel-type NCS and CNS materials were successfully fabricated by this method. When tested as the supercapacitor electrode materials, both NCS and CNS electrodes exhibited battery-type behavior in a three-electrode configuration with outstanding electrochemical performances such as specific capacity, rate performance and cycle stability. Impressively, the CNS electrode delivered a high specific capacity of 430.1 C g−1 at 1 A g−1, which is higher than 345.9 C g−1 of the NCS electrode. Furthermore, the NCS and CNS electrodes showed a decent cycling stability with 75.70 and 84.70% capacity retention after 10,000 cycles. Benefiting from the electrochemical advantage of CNS microspheres, we fabricated a hybrid supercapacitor (HSC) device based on CNS microspheres (positive electrode) and activated carbon (AC, negative electrode), which is named as CNS//AC. The assembled CNS//AC HSC device showed a large energy density of 41.98 Wh kg−1 at a power density of 800.04 W kg−1 and displayed a remarkable cycling stability with a capacity retention of 91.79% after 15,000 cycles. These excellent electrochemical performances demonstrate that both bimetallic NCS and CNS microspheres may provide potential electrode materials for high performance battery-type supercapacitors.

The transition metal sulfides have gained extensive interest in energy storage devices owing to their unique features. However, the research-based on cobalt, copper and manganese sulfide composites is limited while they are considered as promising contenders for supercapacitor electrodes. The simplest and facile one-step electrodeposition technique was adopted for the direct growth of CuMnS and CoMnS on a Ni-substrate. The electrochemical properties of CuMnS and CoMnS electrodes were investigated and maximum specific capacitances of 1691 and 2290 F/g, respectively, were obtained at 10 A/g current density. Further, these electrodes are investigated with activated carbon (AC) electrode to fabricate asymmetric supercapacitor devices where CoMnS//AC exhibited superior energy density values than CuMnS//AC device. However, both the devices show a relatively uniform capacitance retention rate (~94%) after 2500 charging-discharging cycles. Furthermore, the role of capacitive- and diffusive-controlled contributions in the charge storage phenomenon of supercapacitor devices are explicitly scrutinized by employing Dunn's model. Co-electrodeposition of transition metal sulfides has great potential as electrode material for highly effective supercapacitor devices. [ABSTRACT FROM AUTHOR]

Zinc–cobalt double‐metal sulfides (ZCS) as Faradic electrode materials with high energy density have great potential for supercapacitors, but their poor transfer efficiency for electrons and ions hinders their electrochemical response. Herein, ZnCo2(CO3)1.5(OH)3@ZCS microflower hybrid arrays consisting of thin nanolayer petals were anchored on three‐dimensional graphene (ZnCo2(CO3)1.5(OH)3@ZCS/3DG) by a simple hydrothermal method and additional ion‐exchange process. A ZnCo2(CO3)1.5(OH)3@ZCS/3DG electrode delivered high capacitance (2228 F g−1 at 1 A g−1) and long cycling life (85.7 % retention after 17 000 cycles), which are ascribed to the multicomponent structural design. The 3DG conductive substrate improves the electron‐transfer dynamics of the electrode material. Meanwhile, the microflowers consisting of thin nanolayer petals could not only provide many active sites for ions to improve the capacitance, but also alleviate the volume expansion to ensure the structural stability. Furthermore, an all‐solid‐state asymmetric supercapacitor based on a ZnCo2(CO3)1.5(OH)3@ZCS/3DG electrode achieved a high energy density of 27 W h kg−1 at 528.3 W kg−1 and exhibits exceptional cyclic stability for 23 000 cycles. Its ability to light a blue LED for 9 min verified the feasibility of its application for energy storage devices. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries are regarded as one of the most promising next-generation energy storage systems due to their high theoretical volumetric and high weight energy density. However, there are severe problems in the application of lithium-sulfur batteries. The shuttle effect of soluble lithium polysulfide (LiPs) and the low conductivity of sulfur, which leads to slow redox kinetics, are hindering the more significant application of lithium-sulfur batteries. One of the viable solutions to the cathode problem of lithium-sulfur batteries is heterostructured materials. The built-in electric field provided by the heterostructure can significantly accelerate the kinetics of charge transport. In this work, we constructed a heterogeneous structure of G-VS 4 /MoS 2 composites(PVM) modified by Polyvinylpyrrolidone(PVP) is constructed based on graphene, which consists of VS 4 nanosheets and MoS 2 nanosheets grown vertically on graphene lamellae. With weak van der Waals interactions, the one-dimensional (1D) chain-like VS 4 crystal structure enables fast charge transfer in Li-ion batteries. The two-dimensional (2D) lamellar MoS 2 crystals contain Mo-S bonds that also have adsorption effects on polysulfides. Density functional theory (DFT) calculations show that VS 4 and MoS 2 can increase the binding energy of the anode to the polysulfide. Therefore, the S@PVM cathode material provides a large capacity of 1061.4 mAh/g at 0.5 C and can still get to 808.3 mAh/g after 400th cycles. A capacity retention rate of 76.15% is obtained at the same time. It can also boast an initial discharge capacity of 834.8 mAh/g at 1 C. These works can provide more thoughts for developing cathode materials for lithium-sulfur batteries. • G-VS 4 /MoS 2 heterostructures composite was prepared by hydrothermal method modified by Polyvinylpyrrolidone(PVP). • The composite electrode achieves impressive initial capacity and long cycle stability at 0.5 C and 1 C. • The composite electrode can inhibit the shuttle effect effectively and achieve fast electrochemical reaction kinetics. • The composite electrode achieves long cycle stability with a high sulfur loading of 4.6 mg cm−2. [ABSTRACT FROM AUTHOR]

Transition metal sulfide electrode materials have been widely studied in recent years, among which structural control is a terrific way to boost the electrochemical performance. Consequently, in this work, Mn-Ni-Co sulfide composites with a double-layer hollow cage structure were prepared by facile ion etching and hydrothermal vulcanization, and the inherent application value in the field of supercapacitors was verified. Due to the special double-layer hollow structure and the synergy between various metal elements, the prepared electrode material exhibited superior electrochemical performance: the specific capacity reached 2460 F g−1 at the current density of 1 A g−1 and maintained 81.1% even if the current was raised by 20 times. Then, Typha pollen-derived carbon was produced with salt (ZnCl 2 /FeCl 3) activation in one-step calcination. With a Mn-Ni-Co sulfide cathode and a Typha pollen-derived carbon anode, a hybrid supercapacitor device was assembled in a solution of 6 M KOH, which exhibited a great energy density of 80.4 Wh kg−1 at 800 W kg−1 and retained outstanding long-term cycling capability of 78.5% specific capacity after 10,000 cycles. The experimental results exhibit that the prepared composites have non-negligible application feasibility in supercapacitors. In addition, the simple structure control and tunable components make the method easily extended to the preparation of other materials, which has unique reference value for the preparation of multi-metal composites in other fields such as batteries and catalysis. [Display omitted] • The MNCS-2 with double-layer hollow structure and Typha pollen-derived carbon (TPC) was fabricated. • The MNCS-2 exhibits excellent rate performance. • The supercapacitor assembled by MNCS-2//TPC exhibits sufficient energy density. [ABSTRACT FROM AUTHOR]

High-performance of supercapacitors mainly depends on their electrode active materials. Herein, the surface morphology and performance of nickel sulfide (NiS) have been engineered by doping with manganese (Mn). The Mn-NiS nanostructure was synthesized using a facile co-precipitation technique. The feeding ratio of Mn/Ni has a significant impact on the properties. When the Mn/Ni feeding ratio is 1:2, a nanosheet structure is formed and it exhibiting a maximum specific capacitance of 815 g−1 at 2 A−1 and remarkable cycle stability. Besides, oxygen (O) and nitrogen (N) enriched 3D-graphene-like porous activated carbon (ONAC) has been derived from biomass. A hybrid supercapacitor (HSC) is built with Mn-NiS NSs serving as the positive electrode, ONAC as the negative electrode, and PVA/KOH gel as a polymer-gel electrolyte. The constructed device has an impressive specific energy of 44.2 W h kg−1 at 825 W kg−1 specific power. The device also showed exceptional cycling durability with specific capacitance retention of 90% after 5000 charge/discharge cycles at 8 A g−1. HSCs, on the other hand, have been successfully lighted by light-emitting diodes (LEDs), displaying greater energy storage performance. Thus, the present work offers a straightforward way to make nanostructure materials with excellent supercapacitor performance. [Display omitted] • Hierarchical Mn-NiS NSs has achieved with optimum of 1:2 Mn/Ni feeding ratio. • 3D-graphene like O,N-enriched porous carbon has derived from lily flower petals. • Assembled HSC device delivered ultrahigh energy density of ∼44 Wh kg−1 at 825 W kg−1. • The device has specific capacitance retention of 90% after 5000 charge/discharge cycles at 8 A g−1. [ABSTRACT FROM AUTHOR]

• We develop a facile sulfuration treatment approach to synthesize the carbon doped double-shell porous cobalt nickel sulfide microspheres (Co 0.5 Ni 0.5 S 2 -C DSPMs). • The Co 0.5 Ni 0.5 S 2 -C DSPMs) can function as the electrodes for the construction of asymmetric supercapacitors. • The obtained supercapacitors exhibit a maximum specific capacitance of 2011.3 F· g −1 at 1 A· g −1. • The obtained supercapacitors exhibit a high energy density of 64.85 Wh·kg−1 at the power density of 800 W·kg−1. In this research, we develop a facile sulfuration treatment approach to synthesize the carbon doped double-shell porous cobalt nickel sulfide microspheres (Co 0.5 Ni 0.5 S 2 -C DSPMs) using CoNi-MOF yolk-shell microspheres (CoNi-MOF YSMs) as the precursor. The obtained Co 0.5 Ni 0.5 S 2 -C DSPMs exhibits a maximum specific capacity of 2011.3 F g −1 at 1 A g −1 due to the unique double-shell porous structure and amorphous carbon. The density functional theory (DFT) shows that cobalt nickel sulfide with the same molar ratio of cobalt and nickel possesses good absorbability and stability toward OH− ion on the thermodynamics, which significantly improves their electrochemical performance. Furthermore, an asymmetric supercapacitor (ASC) device is fabricated by using Co 0.5 Ni 0.5 S 2 C DSPMs as the cathode and the activated carbon (AC) as the anode. The ASC device exhibits a supreme specific capacity of 182.4 F g −1 at 1 A g −1, a high energy density of 64.85 Wh kg−1 at the power density of 800 W kg−1, and excellent cycle stability with 92.78% capacitance retention rate at the current density of 8 A g −1 over 5000 cycles. This research pave the way for the development of next-generation energy storage devices using micro/nanocomposite with double-shell porous structure. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mn-doped FeS/NC with larger lattice spacing makes Na+ intercalate/de-intercalate more easily. • The volume strain during the cyclic process can be alleviated by multi-core growth mechanism. • The enhanced intercalation increases the reversible capacity of Na+. Owing to their high theoretical capacity, transition metal sulfides are appearing as reliable electrode materials for sodium ion batteries (SIBs), but achieving both high capacity and enduring cyclic stability remain a serious challenge. Here, multi-core Mn-doped FeS/NC was synthesized by one-pot solvothermal and annealing process. Larger lattice spacing, inducing by doping Mn-atoms, provides more space to store sodium ions. The doping of Mn-atoms increases the conductivity, enhancing the transport of charge carrier and rate performance. Multi-core structure and attached carbon can improve tolerance of volume expansion, which is beneficial to the long-term cyclic performance. In addition, it is also proved by density functional theory (DFT) that Mn-doping FeS can enhance the conductivity and lattice spacing. As a result, Mn-doped FeS/NC delivers high reversible capacity (563.3 mAh·g−1 at 0.5 A·g−1), excellent rate capability (442.8 mAh·g−1 at 8 A·g−1) and enduring cyclic stability (206.2 mAh·g−1 after 8000 cycles) as an anode for SIBs. Specially, a cathode of Na 3 V 2 (PO 4) 3 /C is paired with the anode of Mn-doped FeS/NC to assembled into a full battery, showing a highly energy density (281.4 Wh·kg−1 at a power density 625.3 W·kg−1) and capacity retention rate. The present work provide a promise strategy to improve electrochemical performance of the monometallic sulfide. [ABSTRACT FROM AUTHOR]

Preparing hollow materials with a large active surface area is a highlight for energy storage materials. In this work, hollow CuCo 2 S 4 is synthesized via a hard template of commercial Al 2 O 3 at a low cost, and S-vacancies are introduced to enhance the electronic conductivity (rh-CuCo 2 S 4). The template Al 2 O 3 is completely removed by the solvothermal reaction without damaging the hollow structure of CuCo 2 S 4. The rh-CuCo 2 S 4 demonstrates a specific area of 99.5 m2 g–1, higher than that of CuCo 2 S 4 without the Al 2 O 3 template. The rh-CuCo 2 S 4 electrode performs a high specific capacity (247.1 mAh g–1 at 1 A g–1), favorable rate performance, and decent cycling performance (81.1% after 13,000 cycles at 10 A g–1). An asymmetric rh-CuCo 2 S 4 //AC hybrid supercapacitor shows an energy density of 77.6 W h kg–1 at the power density of 612 W kg–1 and a maximum power density of 7.3 kW kg–1 at the energy density of 42.5 W h kg–1. The excellent stability of rh-CuCo 2 S 4 //AC hybrid supercapacitor is also obtained with a retention of 84.9% after 10,000 cycles at 10 A g–1. The favorable performance of rh-CuCo 2 S 4 is attributed to the increasing charge diffusion channels bases on the hollow morphology and the enhanced electronic conductivity and reaction activity due to S-vacancies. This work provides a low-cost and efficient approach to preparing sulfides with high performance in energy storage applications. [ABSTRACT FROM AUTHOR]

In this work, using a Co-based metal organic framework (Co-MOF) array as precursor, the high performance supercapacitor positive electrode (CNVS: Ni/V-doped Co 3 S 2 @Co/Ni-doped VS 2 hetero-structure) and negative electrode (CNFS: Fe/V-doped Co 3 S 2 @Co/Fe-doped VS 2 hetero-structure) are successfully constructed by a "one-for-two" synthesis strategy. Benefiting from their unique hollow triangular arrays, rich mesoporous structure constructed by M 3 S 2 /MS 2 heterogeneous interface, abundant active centers originating from the defect of elements doping, the optimized CNVS and CNFS can improve the transfer ratio of electrons and electrolytes for fast kinetics, and provide more electroactive sites for deeply redox reaction. Therefore, an outstanding specific capacitance of 6556 mF cm−2 (910.56 μA h cm−2) is achieved by CNVS electrode under 0–0.5 V (vs. Hg/HgO) at 2 mA cm−2, and the CFVS electrode displays a high specific capacitance of 6195 mF cm−2 (1720 μA h cm−2) under −0.1 to −1.1 V range (vs. Hg/HgO) at 5 mA cm−2. Furthermore, a high-performance hybrid supercapacitor (HSC) is assembled with CNVS as the positive electrode, and CFVS as the negative electrode, which presents an ultrahigh energy density of 0.83 mWh cm−2 at a power density of 4.56 mW cm−2, and excellent cycle performance of maintaining 79.6% initial capacity after 5000 cycles. [Display omitted] • The positive and negative electrode materials are prepared by one MOF precursor. • The as-prepared materials present trimetal co-doped M 3 S 2 /MS 2 hetero-structure. • The M 3 S 2 are distributed on the MS 2 nanoplates to form hollow triangle arrays. • The HSC device presents an outstanding energy density of 0.83 mWh cm−2. [ABSTRACT FROM AUTHOR]

Featuring high electrical conductivity and electrochemical activity, transition metal sulfides are promising materials for the positive electrode of hybrid supercapacitors. However, considering their poor cycling life and rate performance, critical challenges remain. In this contribution, we describe hollow NiS 2 /CoS 2 @C composites obtained by stepwise etching, annealing, and sulfuration of ZIF-67. Specifically, NiS 2 /CoS 2 particles were dispersed on N/S co-doped carbon nanocages and found to exhibit outstanding stability and rate performance. The unique nanocage structure of N/S co-doped carbon and heterogeneous interfaces of NiS 2 and CoS 2 can promote both ion transport and electron transfer, enriching the active site for enhanced reactivity. The resulting NiS 2 /CoS 2 @C nanocage composites in fact showed considerable electrochemical performance, with a specific capacity of 1373 C g-1 at 1 A g-1. When combined with reduced graphene oxide (RGO)-based negative electrode, the assembled hybrid supercapacitor registered an energy density of 63.3 Wh kg-1 at a power density of 800 W kg-1, retaining exceeding 98% of the initial capacity even after 13,000 cycles. [Display omitted] [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotube (MWCNT)/Ni-Mn-S composites are derived from MWCNT/Ni/Mn bimetallic metal-organic framework (MOF) for supercapacitor electrodes. Electroconductive MWCNT is introduced into Ni-Mn-S to form a three-dimensional interconnected structure due to the covalent interaction between Ni atoms and C atoms. During energy storage, MWCNT serves as miniature current collector to shorten pathway of electron collection and transmission. In addition, S2- etching agent with Kirkendall effect makes edges and surfaces of the resulted sulfide structures rougher provide more active sites and improves electrochemical performance compared with precursors. By finely adjusting Ni/Mn molar ratio, the prepared MWCNT/Ni-Mn-S composite achieves excellent properties. As-prepared MWCNT/Ni-Mn-S(3:2) exhibits high specific capacitance of 1041 mAh g−1 at 1 A g−1 and good cyclic stability. The capacitance retention reaches 83.3% after 10,000 cycles. The assembled MWCNT/Ni-Mn-S(3:2)//AC hybrid supercapacitor (HSC) also shows high energy density of 25.33 Wh Kg−1 at power density of 829 W Kg−1 and outstanding cycling stability (93.3% after 20,000 cycles), which illustrates MWCNT/Ni-Mn-S(3:2) has important potential in supercapacitor. [Display omitted] • MWCNT/Ni-Mn-S(3:2) is derived from corresponding MWCNT/MOF-Ni/Mn for supercapacitors. • MWCNT/Ni-Mn-S(3:2) electrode shows high specific capacitance of 1041 mAh g−1. • Assembled MWCNT/Ni-Mn-S(3:2)//AC HSC delivers high specific capacitance and excellent cyclic stability. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) have been widely researched as promising electrode materials for supercapacitors because of their high theoretical capacitance and rich redox reactive sites. In this work, tremella-like core-shell Co 9 S 8 @NiCo 2 S 4 heterogeneous nanosheets were directly grown on Nickel foamed (NF) through the hydrothermal+electrodeposition method to obtain a self-supporting electrode. Benefiting from its unique tremella-like structure, ultra-thin nanosheets, and the positive synergies between Co 9 S 8 and NiCo 2 S 4 , the prepared Co 9 S 8 @NiCo 2 S 4 @NF electrode presents a high specific capacity of 513 C g−1 (specific capacitance ~1026 F g−1) at 1 A g−1 with superior rate capability (62.8% capacitance retention rate at 10 A g−1). Furthermore, the fabricated Co 9 S 8 @NiCo 2 S 4 @NF//active carbon (AC) hybrid supercapacitor displays a high energy density of 30 Wh kg−1 at a power density of 731.8 W kg−1 and superior cycling stability. The results prove that the strategy of hydrothermal+electrodeposition is a very effective method for the preparation of energy storage and conversion materials with unique core-shell morphology. [Display omitted] • An integrated Co 9 S 8 @NiCo 2 S 4 @NF electrode is prepared. • Co 9 S 8 @NiCo 2 S 4 @NF presents a tremella-like porous structure. • The specific capacitance of Co 9 S 8 @NiCo 2 S 4 @NF can reach up to 1026 F g−1 at 1 A g−1. • A Co 9 S 8 @NiCo 2 S 4 @NF//AC hybrid supercapacitor is constructed. • The Co 9 S 8 @NiCo 2 S 4 @NF//AC displays a high energy density of 30 Wh kg−1. [ABSTRACT FROM AUTHOR]

• Bimetallic (Ni,Mo)S 2 was synthesized through a two-step solvothermal approach. • The (Ni,Mo)S 2 /G composite exhibits high specific capacity of 951 C g−1. • The ASC device shows a ultrahigh energy density of 84.5 Wh kg−1. Thanks to their high electrical conductivity, electrochemical stability and activity, transition metal sulfides have been widely designed and developed for supercapacitors with excellent electrochemical performances. Herein, we report the NiS 2 /MoS 2 mixed phases with abundant exposed active edge sites decorated on graphene nanosheets (named as (Ni,Mo)S 2 /G) through a facile two-step hydrothermal approach. Benefitting from its unique chemical property and structure, the as-prepared (Ni,Mo)S 2 /G composite possesses impressive electrochemical performances as electrodes of battery-type supercapacitors in 2 M KOH, such as high specific capacity of 951 C g−1 (2379 F g−1) at 1 A g−1 with superb rate capability (60.7% at 100 A g−1). Additionally, the asymmetric supercapacitor (ASC) device assembled based on the active edge site-enriched (Ni,Mo)S 2 /G as positive electrode and nitrogen-doped porous graphene as negative electrode displays an ultrahigh energy density of 84.5 Wh kg−1, superior to those of the Ni- and Mo-based ASCs in aqueous electrolytes reported so far. Such novel strategy may hold great promise for exploring other polymetallic sulfides with abundant exposed active edge sites for energy storage and conversion. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) have recently emerged as promising hierarchical structured porous materials for high-performance energy storage and conversion devices due to their unique tunable structure and excellent porosity. Herein, we reported a "one for two" strategy to prepare NiCo 2 S 4 nanorods directly grown on carbon cloth (NiCo 2 S 4 @CC) via a simply modified MOFs-derived approach for high-performance asymmetric supercapacitors and efficient oxygen evolution reaction (OER). As an electrode for asymmetric supercapacitors, the NiCo 2 S 4 @CC electrode showed excellent electrochemical performance with high specific capacitance and good rate capability. The asymmetric supercapacitor using NiCo 2 S 4 @CC as a cathode electrode and N-doped porous carbon nanosheets grown on the CC (NC@CC) as an anode electrode achieved a superior energy density and power density and a long cycle life. Furthermore, the NiCo 2 S 4 @CC exhibited a notable electrocatalytic activity as an electrocatalyst for OER. The remarkable electrochemical performance of as-prepared NiCo 2 S 4 @CC could be mainly attributed to its hierarchical structure, sufficient active sites and low metal-anion bond energy after sulfuration reaction. This work could provide an unprecedented opportunity to fabricate functional materials under rational design for various applications. [ABSTRACT FROM AUTHOR]

Electrode materials with a large internal surface area, tunable pore size, efficient transport of electrons and high ion-accessibility are highly desired in the development of advanced flexible supercapacitors. Recently, transition metal sulfides with rationally designed nanostructures have attracted considerable attention as electrode materials for supercapacitors. In this study, we report the synthesis of Zn 0.76 Co 0.24 S/NiCo 2 S 4 nanosheets grown on carbon cloth using a two-dimensional bimetallic Zn/Co zeolitic imidazolate framework (named as Zn/Co-ZIF-L) as a precursor through a simple and cost-effective chemical solution process. The ZIF-derived Zn 0.76 Co 0.24 S/NiCo 2 S 4 electrode nanosheets deliver an ultrahigh specific capacitance of 2674 F g−1 at 1 A g−1, a superior ratio performance and cycle stability. Furthermore, the as-fabricated Zn 0.76 Co 0.24 S/NiCo 2 S 4 //AC all-solid-state asymmetric supercapacitor (ASC) achieves a maximum energy density of 48.1 Wh kg−1 as well as a power density of 837 W kg−1, and a superior cycling performance of 91% retention after 5000 cycles. The detailed electrochemical kinetic analysis demonstrates that the total capacitance of Zn 0.76 Co 0.24 S/NiCo 2 S 4 is derived from its capacitive-effective charge storage mechanism. This ZIF-derived strategy provides a reasonable and simple way to synthesize transition metal sulfides as potential active materials for next-generation flexible supercapacitors. Image 1 • Zn/Co-based MOFs derived Zn 0.76 Co 0.24 S/NiCo 2 S 4 nanosheets were prepared successfully. • The Zn 0.76 Co 0.24 S/NiCo 2 S 4 electrode exhibited remarkable specific capacitance. • A flexible all-solid-state Zn 0.76 Co 0.24 S/NiCo 2 S 4 //AC ASC device was fabricated. • The enhanced property is due to the nanostructure, porosity and conductivity. [ABSTRACT FROM AUTHOR]