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Room‐temperature sodium–sulfur (RT/Na–S) batteries are regarded as promising large‐scale stationary energy storage systems owing to their high energy density and low cost as well as the earth‐abundant reserves of sodium and sulfur. However, the diffusion of polysulfides and sluggish kinetics of conversion reactions are still major challenges for their application. Herein, we developed a powerful and functional separator to inhibit the shuttle effect by coating a lightweight three‐dimensional cellulose nanofiber‐derived carbon aerogel on a glass fiber separator (denoted NSCA@GF). The hierarchical porous structures, favorable electronic conductivity, and three‐dimensional interconnected network of N,S‐codoped carbon aerogel endow a multifunctional separator with strong polysulfide anchoring capability and fast reaction kinetics of polysulfide conversion, which can act as the barrier layer and an expanded current collector to increase sulfur utilization. Moreover, the hetero‐doped N/S sites are believed to strengthen polysulfide anchoring capability via chemisorption and accelerate the redox kinetics of polysulfide conversion, which is confirmed from experimental and theoretical results. As a result, the assembled Na–S coin cells with the NSCA@GF separator showed a high reversible capacity (788.8 mAh g−1 at 0.1 C after 100 cycles) and superior cycling stability (only 0.059% capacity decay per cycle over 1000 cycles at 1 C), thereby demonstrating the significant potential for application in high‐performance RT/Na–S batteries. [ABSTRACT FROM AUTHOR]

Rural energy is an important part of China's energy system, and, as China's agricultural modernization continues, integrated agricultural energy systems (AIES) will play an increasingly important role. However, most of China's existing rural energy systems are inefficient, costly to run, and pollute the environment. Therefore, meeting various agricultural energy needs while balancing energy efficiency and costs is an important issue in the design and dispatch of integrated agricultural energy systems. In conjunction with hybrid energy storage (HES), which has been developed and matured in recent years, this paper proposes a new type of AIES structure and optimal dispatching strategy that incorporates HES, biogas generation (BG), P2G, and an electric boiler (EB) to provide new ideas for problem solving. Firstly, the structure of AIES is introduced and the mathematical model of the equipment of the system is described; then, an economic optimal dispatching model with the objective of minimizing the comprehensive operating costs of the system is established, and the output of each piece of energy conversion equipment is controlled to achieve the effect of improving the system's operating performance and reducing the operating costs. The results show that the system with HES and multi-energy coupling equipment has a 20% lower overall cost, 23.2% lower environmental protection cost, and 51% higher energy efficiency than the original system; the stored power of energy storage equipment in the HES mode is primarily determined by the change in demand of the corresponding load, and the number of conversions between different energy sources is limited. The energy conversion loss is minimal. [ABSTRACT FROM AUTHOR]

With the rapid development of wearable and intelligent flexible electronic devices (FEDs), the demand for flexible energy storage/conversion devices (ESCDs) has also increased. Rechargeable flexible metal‐air batteries (MABs) are expected to be one of the most ideal ESCDs due to their high theoretical energy density, cost advantage, and strong deformation adaptability. With the improvement of the device design, material assemblies, and manufacturing technology, the research on the electrochemical performance of flexible MABs has made significant progress. However, achieving the high mechanical flexibility, high safety, and wearable comfortability required by FEDs while maintaining the high performance of flexible MABs are still a daunting challenge. In this review, flexible Zn‐air and Li‐air batteries are mainly exemplified to describe the most recent progress and challenges of flexible MABs. We start with an overview of the structure and configuration of the flexible MABs and discuss their impact on battery performance and function. Then it focuses on the research progress of flexible metal anodes, gel polymer electrolytes, and air cathodes. Finally, the main challenges and future research perspectives involving flexible MABs for FEDs are proposed. [ABSTRACT FROM AUTHOR]

Among a large variety of energy storage technologies, supercapacitors possess special advantages such as rapid charge/discharge, high power density, safety, and environmental friendliness to meet the requirement of specific applications. The common electrode materials of supercapacitors, including porous carbon, conductive polymers, and metal oxides/hydroxides, have their own benefits and drawbacks in energy density and stability. Owing to the big surface area and controllable porosity, the metal-organic frameworks (MOFs) have been explored as important candidates for supercapacitor applications. This mini-review focuses on the recent advances of MOF-based materials including pristine MOFs, MOFs composite materials, and MOF-derived materials in the development of long cycling life supercapacitors. The devices discussed here mean those with capacitive retention rates of more than 90% after 10,000 cycles and high energy density. In addition, we also describe the fundamental knowledge of supercapacitors, highlight the stabilization mechanism of MOFs, and propose the strategies to enhance the stability of MOF-based supercapacitor electrodes. • The fundamental knowledge of supercapacitor is illustrated. • The fundamental mechanisms of MOFs stabilization are emphasized. • Recent advances of MOF-based long cycling stability supercapacitors are reviewed. • The strategies to enhance the stability of MOF-based supercapacitors are proposed. [ABSTRACT FROM AUTHOR]

A new covalent organic framework material (NWNU-COF-1) linked with –NH– bonds is synthesized by the condensation reaction of melamine and 2,4,6-trichloro-1,3,5-triazine and its structure and properties are characterized by Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The BET specific surface area of NWNU-COF-1 is 301.149 m2 g−1, and the pore size is about 1.41 nm. The preparation is also simple and cheap. This material exhibits a significant pseudocapacitance characteristic in a 6 M potassium hydroxide electrolyte, and the highest specific capacitance value of 155.38 F g−1 at 0.25 A g−1 current density in a three electrode configuration. This COF also demonstrates about 100% capacitance retention after 20 000 galvanostatic charge–discharge cycles, which is equal, even better compared with the COF materials reported previously, the nano/mesoporous carbon materials and even nitrogen doped carbons. [ABSTRACT FROM AUTHOR]

The ultrathin porous carbon shell with the thickness of about 10 nm has been fabricated by a facile method using sodium citrate as carbon precursor without any activation. The electric conductivity of the material is as high as 7.12 S/cm, which contributes to a good rate performance for supercapacitor electrode without any conductive additive. When tested in 6 M KOH by three-electrode system, the C-700 sample exhibits specific capacitance of 251 F g −1 at 1 A g −1 , high rate capability with the specific capacitance of 228 F g −1 at 20 A g −1 , only a loss of 3% after 10000 cycles at a current density of 3 A g −1 . Non aqueous performance was tested in 1 M TEA-BF 4 /acetonitrile, the material can deliver an energy density of 12–17 Wh kg −1 in a two-electrode system. Apparently, the porous carbon with ultrathin structure can provide low-resistant pathways and short ion diffusion channels for energy storage. Therefore, the ultrathin porous carbon shell would be a promising material particularly for applications where high power output performances are required. [ABSTRACT FROM AUTHOR]

The aprotic Li-O2 battery has attracted a great deal of interest because, theoretically, it can store far more energy than today's batteries. Toward unlocking the energy capabilities of this neotype energy storage system, noble metal-catalyzed high surface area carbon materials have been widely used as the O2 cathodes, and some of them exhibit excellent electrochemical performances in terms of round-trip efficiency and cycle life. However, whether these outstanding electrochemical performances are backed by the reversible formation/decomposition of Li2O2, i.e., the desired Li-O2 electrochemistry, remains unclear due to a lack of quantitative assays for the Li-O2 cells. Here, noble metal (Ru and Pd)-catalyzed carbon nanotube (CNT) fabrics, prepared by magnetron sputtering, have been used as the O2 cathode in aprotic Li-O2 batteries. The catalyzed Li-O2 cells exhibited considerably high round-trip efficiency and prolonged cycle life, which could match or even surpass some of the best literature results. However, a combined analysis using differential electrochemical mass spectrometry and Fourier transform infrared spectroscopy, revealed that these catalyzed Li-O2 cells (particularly those based on Pd-CNT cathodes) did not work according to the desired Li-O2 electrochemistry. Instead the presence of noble metal catalysts impaired the cells' reversibility, as evidenced by the decreased O2 recovery efficiency (the ratio of the amount of O2 evolved during recharge/that consumed in the preceding discharge) coupled with increased CO2 evolution during charging. The results reported here provide new insights into the O2 electrochemistry in the aprotic Li-O2 batteries containing noble metal catalysts and exemplified the importance of the quantitative assays for the Li-O2 reactions in the course of pursuing truly rechargeable Li-O2 batteries. [ABSTRACT FROM AUTHOR]

This paper proposes a novel transient reconfiguration solution and coordinating control strategy for power converters to enhance the fault ride through and transient voltage support capabilities of a doubly-fed induction generator with an energy storage device (DFIG-ESD). During a grid fault, the connection of the grid-side converter is reconfigured such that it is connected to the rotor circuit in parallel with the rotor-side converter to provide an additional route for the rotor current, while the ESD is responsible for dc-link voltage regulation. A coordinated demagnetizing and reactive current control strategy is designed for the reconfigured DFIG during transient conditions. Specifically, the demagnetizing current is used to counteract the dc and negative-sequence stator flux components so that the transient electromotive force will be reduced. Simultaneously, the reactive current is added to meet the reactive power support requirement. The enhanced low-voltage ride through (LVRT) and transient voltage support capabilities obtained from the proposed design are demonstrated on the DFIG-ESD wind conversion system under different severe fault scenarios (asymmetrical and symmetrical fault). Additionally, The enhanced transient voltage support capability of the proposed design is further demonstrated by comparing with different control strategies. [ABSTRACT FROM AUTHOR]

• Highly flexible CNT scaffolds were prepared and firstly used to stabilize Zn anodes. • The CNT scaffold-stabilized Zn anodes displayed superior cycling stability. • Ultralong-life zinc-ion batteries/hybrid capacitors with Zn anodes were constructed. The merits of zinc metal anodes such as high chemical stability, low cost and ultrahigh volumetric capacity endow Zn based batteries/hybrid capacitors with great potential applications for electronic products. However, unstable stripping/plating of zinc anodes tends to cause the formation of protuberances/dendrites and side reactions such as water decomposition on anode surfaces, eventually leading to the failure of Zn based electrochemical energy storage devices. Herein, we report the fabrication of free-standing, highly flexible and conductive carbon nanotube (CNT)/paper scaffolds to stabilize zinc metal anodes. The free-standing CNT scaffolds only need to be placed between zinc anodes and separators when assembling zinc anode-based batteries/hybrid capacitors. On the surface of the zinc electrode, the scaffolds' porous skeleton mechanically regulates Zn2+ deposition sites and their conductive CNT networks maintain a stable electric field during Zn stripping/plating processes, thus retarding the formation of protuberances/dendrites and the occurrence of side reactions. The scaffold-stabilized zinc anodes displayed small polarization voltages, a long cycling life over 1800 h and superior capability for fast charging-discharging. In addition, benefiting from the high electrochemical stability and reversibility of the scaffold-stabilized zinc anodes, zinc-ion batteries/hybrid capacitors with ultralong cycle lives were successfully constructed. This work provides a scalable approach to stabilize zinc metal anodes for long-life zinc-ion batteries and zinc-ion hybrid capacitors. [ABSTRACT FROM AUTHOR]

Nanoflower‐like composites have greater contact area and more redox reactive centers, which have great potential in the application of electrode materials for supercapacitors. A nonconductive polymer binder is usually used in preparation of electrodes, which causes an increase in interface resistance and a decrease in material active sites. Here, polyaniline (PANI) and ZIF‐9 are directly grown on the Ni foam (ZIF‐9@PANI/NF) by a simple solvothermal method without a nonconductive polymer binder. A nanoflower array is grown on the NF, which can be directly used as electrode material of supercapacitor. The attachment of PANI facilitates electron transfer and increases the conductivity of the material. At a current density of 1 A g−1, the specific capacitance is up to 7 times that of the ZIF‐9. The assembled asymmetric supercapacitor has a high energy density of 52 Wh kg−1 at a power density of 800 W kg−1, remaining 90.1% after 50 000 cycles. These great electrochemical properties show the material has good market development prospects for energy storage device. [ABSTRACT FROM AUTHOR]

Nickel-cobalt sulfides (NiCo 2 S 4) with abundant valence states are promising electrode materials for multiple faradaic reactions in hybrid supercapacitors. However, the slow electron transfer kinetics and lack of active sites restrict its electrochemical activity. Herein, an effective synthesis strategy was proposed to synergistically improve the electrochemical performance of NiCo 2 S 4 through one-step in-situ carbonization-vulcanization method of metal-organic frameworks (MOF). Through rational selection and optimization of the Ni:Co ratio, the fibre-assembled urchin-like 3D nanoflowers (denoted as NCSC) possess abundant sulfur vacancies and appropriate porosity. Interestingly, the S vacancies can expose more redox active sites, while the expandable 3D carbon conductive network can accelerate electron transport. Furthermore, the electrical conductivity and interfacial activity is synergistically enhanced by strong electronic coupling effects. Experimental results reveal that the NiCo 2 S 4 /C exhibit excellent electrochemical performance as a battery-type electrode material. The specific capacitance is 1934 F·g−1 (967 C·g−1) at 1 A·g−1 and the capacitance retention is 93.2% after 5000 cycles at 5 A·g−1. The assembled hybrid supercapacitor device (NiCo 2 S 4 /C//AC) exhibits an exceptionally high energy density of 50.24 Wh·kg−1 at power density of 800 W·kg−1. These results have significant implications for the optimization of the transition metal compounds for electrochemical energy-storage devices. [Display omitted] • The sulfur vacancy-rich 3D fibrous nanoflowers is synthesized successfully. • The in situ generated carbon network modulates the intrinsic electronic/surface structure. • One-step vulcanization-carbonization achieves highly dispersive S vacancies-rich NiCo 2 S 4. • Highly graphitized 3D nanostructures shows high specific capacitance of 1934 F·g−1 at 1 A·g−1. [ABSTRACT FROM AUTHOR]

As a kind of energy storage device, supercapacitors have attracted the attention of researchers, and the development of high-performance electrode materials is also the focus of attention. In this paper, template synthesis and pyrolysis were combined to prepare high performance porous carbon electrode materials. The carbonized electrode material effectively increased the capacitance storage capacity and charge transfer rate. The results revealed that the derivative had a relatively low charge-transfer resistance and high specific capacitance of 1059 F·g−1 at a current density of 1.0 A·g−1 in a three-electrode system. To further exploring practical application, a device based on the derivative and hemp-activated carbon asymmetric supercapacitor was assembled in 0.1 M Na 2 SO 4 neutral electrolyte, which exhibited an energy density of 20.35 Wh·kg−1 at a power density of 400 W·kg−1. Interestingly, it showed capability retention of nearly of 91.7% and columbic efficiency of 100% even after 10000 charging/discharging cycles in the neutral electrolyte. Image 1 • The aqueous NPCZ-3//HAC ASC is assembled in 0.1 M Na 2 SO 4 neutral electrolyte. • Both cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) curves of ASC display pip symmetric characteristic. • The as-assembled ASC delivers a nearly of 91.7% capability retention after 10000 cycles. • The ASC delivers has a coulomb efficiency of 100% after 10000 cycles in a neutral electrolyte. [ABSTRACT FROM AUTHOR]

Abstract In this work, a Co-ZIF material and the derived nanoporous cobalt-rich carbons by direct carbonization of this Co-ZIF material were synthesized and used as electrode materials for supercapacitors. This ZIF material exhibited a high specific capacitance of 160.3 F g−1 at 0.5 A g−1, an excellent rate capability (73.72 F g−1 at 10 A g−1), and a good cycling stability with 100% of its initials specific capacitance after 8000 cycles. In addition, the obtained derived nanoporous carbons displayed ideal capacitor behaviors and were promising electroactive materials for supercapacitors at low current density. The nanoporous carbon obtained at 650 °C possessed a highest specific capacitance of 393 F g−1 at 0.5 A g−1 and a wide potential application range of −1.0–0.33 V. In addition, a symmetric supercapacitor device consisting of Z-C-650 and activated carbon exhibited a maximum energy density of 61.23 Wh Kg−1 at a power density of 700 W kg−1 and predicted that Z-C-650 could be used as a potential energy storage material. Graphical abstract Image 1 Highlights • Cobalt zeolite imidazolate framework and derived nanoporous carbons were prepared. • The framework and the derived carbons showed good electrochemical properties. • The assembled symmetric supercapacitor showed good performances. • The capacitor had energy density of 61.23 Wh kg−1 at 700 W kg−1 power density. [ABSTRACT FROM AUTHOR]

Bimetallic metal-organic frameworks (MOFs) with a controlled morphology are potential materials for boosting the electrochemical performance of supercapacitors owing to their unique structural merits. Herein, a solvent-regulated strategy was proposed to synthesize bimetallic MOFs with various morphologies, such as microflowers, microspheres, and nanosheets, and the possible mechanisms of morphology control during nucleation and crystal growth were analyzed. When employed as electrode materials for supercapacitors, the NiCo-MOF microflowers possessed the biggest specific capacitance, which could achieve 1086 F g−1 at a current density of 1 A g−1. To further improve the electrochemical performance of materials, NiCo-P was prepared via a low-temperature phosphating method using NiCo-MOF microflowers as the precursor. Electrochemical studies displayed that the NiCo-P(6) microflowers exhibited good capacitance and superior rate capability with specific capacitances of 1592 and 1384 F g−1 at 1 and 20 A g−1, respectively. Furthermore, an asymmetric supercapacitor assembled by NiCo-P(6) and active carbon exhibited a high energy density of 51.2 Wh kg−1 at a power density of 749.8 W kg−1 and outstanding cycling stability. This work is easy to operate and can be extended to the preparation of other MOF-based electrode materials. The delivered excellent electrochemical performance suggests the resulted flower-like NiCo-P is a promising electrode material for advanced energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

As a typical pseudocapacitance material, NiS is considered a promising electrode material due to its high theoretical specific capacitance and abundant reserves. However, the electrical conductivity is poor, resulting in a decrease in cycle stability and rate performance. Here, we introduce cobalt-containing porous nanocarbon (Co-NC) derived from zeolite-imidazolate frameworks (ZIFs) as a supporting base to design a hybrid structure. As an electrode material, NiS@Co-NC nanocomposite has a composite effect of double-layer capacitive porous carbon and pseudo-capacitance NiS nanoparticles and excellent electrochemical performance. Specifically, the specific capacitance of NiS@Co-NC nanocomposite is as high as 1116.6 F·g−1 when the current density is 1 A·g−1, and capacity retention is 90.177% at a very high current density of 10 A·g−1 after 5000 cycles. Moreover, the fabricated hybrid supercapacitor delivers an energy density of 21.6 Wh·kg−1 at 799.9 W·kg−1 with coulombic efficiency of 90.177%, and 14.22 Wh·kg−1 at a high power density of 7999.9 W·kg−1, along with excellent cyclic stability of 89.85% at 5 A·g−1 after 5000 cycles. All results indicate that NiS@Co-NC nanocomposites have the potential to be applied as electrodes in hybrid supercapacitors and other energy storage devices. ZIF-67 @ZIF-8 was synthesized through hydrothermal reaction and carbonized as a sacrificial template to generate cobalt-containing nano-carbon and carbon nanotubes. [Display omitted] • CNTs interconnected NiS@Co-containing porous carbon nanocomposite was synthesized. • The composite showed a strong synergistic effect of NiS, CNTs and metallic cobalt modified porous carbon. • NiS@Co-NC nanocomposite has a high specific capacitance of 1116.6 F.g-1 1 A.g-1. [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]

The caCTF-1 derived from CTF-1 by carbonization is introduced into the multi-step heat treatment carbon repaired pC-C 3 N 4 to form a 3D interconnected nitrogen-rich carbon structure (caC@pC). Through carbon repairing process, the obtained pC-C 3 N 4 has an extended π-conjugate plane and it is closely interconnected with the nitrogen-rich caCTF-1, thereby accelerating charge transfer, improving energy storage, and exhibiting high specific capacitance (535.8 F·g−1 under 1 A·g−1) and good rate performance. In addition, by employing MOF with diphenyl semicarbazide structural unit as a precursor, NiCoTe 2 is prepared by a simple hydrothermal process, which exhibits high redox activity with a high specific capacitance of 2006.0 F·g−1 at 1 A·g−1 and good cycle stability. The hybrid supercapacitor NiCoTe 2 //caC@pC HSC is assembled with caC@pC as the negative electrode and NiCoTe 2 as the positive electrode. When the power density is 790.05 W·kg−1, it exhibits a high energy density of 50.84 Wh·kg−1 and high cycle stability. After 25,000 cycles, the capacitance retention rate is 87.88%. • A three-dimensional cross-linked nitrogen-rich carbon material caCTF-1 @pC-C 3 N 4 was constructed. The 3D cross-linked structure facilitates the rapid penetration of electrolyte ions. The introduction of nitrogen source into the carbon material can enhance the surface charge mobility of carbon. The material exhibits high specific capacitance (535.8 F·g−1 under 1 A·g−1) and good rate performance (the specific capacitance still remains 85.67% at 10 A·g−1) in the three-electrode test. • caCTF-1 is derived from CTF-1. This material has a high nitrogen content and was first used in supercapacitors, showing better application potential. • The carbon self-repairing pC-C 3 N 4 can be combined with ethanol to introduce carbon units into g-C 3 N 4 through the hydrothermal method, which improves the slow charge transfer due to the limitation of bridge nitrogen atoms. Multi-step heat treatment also makes it have more pores. Thereby improving electrochemical performance. • NiCoTe 2 with broccoli structure provides fast Faraday reaction active sites, ensures high utilization of electrode materials, and enables electrode active materials to exhibit ultra-high specific capacitance (2006 F/g at 1 A/g), rate performance and good cycle stability (when assembled into a supercapacitor, the capacitance retention rate after 20,000 cycles is 96.15%). • The assembled asymmetric supercapacitor NiCoTe 2 //caC@pC has a large potential window (0–1.6 V) and high energy density (when the power density is 790.05 W/kg, the energy density is 50.84 Wh/ kg), and good cycle stability. [ABSTRACT FROM AUTHOR]

• Ni-MOF on MXene is vulcanized to sandwiched p-MXene/Ni 3 S 4 /CuS in the presence of copper. • p-MXene/Ni 3 S 4 /CuS show the remarkable specific capacitance. • The p-MXene/Ni 3 S 4 /CuS//AC has a high energy density and ultrahigh cyclic stability. [Display omitted] Metal-organic frameworks (MOFs) have ordered porous structure and intriguing properties for supercapacitors, however, poor conductivity and cycle stability limits their application. To solve these problems, hence, a simple strategy is proposed, by which MOFs are in-situ grown in the porous conductive p-MXene substrate. And then, along with the introduction of CuS, the grown Ni-MOF is derived to Ni 3 S 4 , which is more stable and more electrochemically active. Due to higher contact area, excellent synergistic effect and more exposed active sites, the prepared sandwiched p-MXene@Ni 3 S 4 /CuS nanostructure displays a big specific capacitance (1917 F·g−1) and superior cycling performance (91.2%@30000). What's more, the assembled p-MXene@Ni 3 S 4 /CuS//AC asymmetric device delivers a high energy density of 87.62 Wh·Kg−1 at the power density of 775.02 W·Kg−1, suggesting that this material provides a brilliant candidate for energy storage. [ABSTRACT FROM AUTHOR]

In this paper, novel hybrid nanomaterials constituting carbonized biomass materials derived from walnut shells and metal-organic framework (MOF) have been researched as a new class of renewable supercapacitor materials for electrochemical energy storage. One synthetic route is employed to grow Ni-MOF in the peripheries and channels of walnut shells derived carbon (WS), which had been carbonized previously by heat treatment in air at 850 °C to produce a highly porous network, and vulcanized polyaniline (SPANI) is used as a dummy plate preventing the agglomeration of MOFs and a wire connecting WS and MOFs, which easily improves the electron transfer and enhances the conductivity of the electrode material. The specific capacitance of the obtained WS@Ni-MOF composite is up to 4 times that of the biochar at the current density of 1 A g-1. The connection of SPANI also obviously accelerates the transfer of electrolyte ions. The resulting specific capacitance could reach 14 times of the biochar and exhibit high cycle stability (retention rate of 90.4% after 20000 cycles). In addition, the assembled asymmetrical supercapacitor (ASC) shows a high energy density of 34.79 Wh kg-1 at the power density of 824 W kg-1. This work provides a brilliant renewable candidate for the excellent energy storage device and a promising route design strategy for preparation of high performance and long life electrode materials. [Display omitted] • Design and fabrication of self-assembled Walnut shell-derived carbon and MOF composites. • WS@Ni-MOF/SPANI, as a new electrode material with sandwich structure, applied for supercapacitors for the first time. • The specific capacitance of WS@Ni-MOF/SPANI is greater than that of WS, Ni-MOF and SPANI. • Excellent cyclic stability of WS@Ni-MOF/SPANI (90.4%@20000). [ABSTRACT FROM AUTHOR]

• A simple ultrasound-assisted method was used to synthesize nitrogen-containing p - π conjugated-organic ligands. • Nitrogen-containing conjugated organic ligands have good conductivity. • Carbon-enriched MOFs and derived porous carbon have excellent electrochemical performance. • The change law of electrochemical performance was explored with gradient temperature. • The MOF-B-600//AC ASC device exhibits a high energy density of 63.62 Wh·kg−1 at power density of 400 W·kg−1. [Display omitted] This article aims to use nitrogen-doped metal p - π conjugated-organic frameworks and derived carbon-rich electrode materials for high-performance electrode materials. Nitrogen-doped contributes to the energy storage performance, and the p-π conjugated-organic ligands of the conjugated system can not only improve the stability of the structure, but increase the conductivity of the material. Gradient carbonization can explore the maximum electrochemical potential of MOF-B, from which the previous 1271.0 increased to 2727.5 F·g−1 at a current density of 1.0 A·g−1. The excellent capacitance retention rate is 86.67% of the initial value at a high current density after 20,000 cycles. Besides, the MOF-B-600//AC also shows a high energy density of 63.62 Wh·kg−1 at a power density of 400 W·kg−1 and good coulomb efficiency of 90.7%. As a result, the excellent electrochemical performance of the nitrogen-doped and carbon-enriched MOF-B-600 has potential application prospects in energy storage devices. [ABSTRACT FROM AUTHOR]

Sandwich-like layered composite materials possess a high contact area and can expose many reactive active sites, which exhibit great potential in the application of supercapacitors. In this paper, a sandwich-like composite material was synthesized based on polyaniline (PANI), graphene oxide (GO) and ZIF-67 (denoted as GO@ZIF-67/PANI). Among them, GO is designed as a deposition substrate of ZIF-67 and transfer scaffold of electrons and PANI works as a wire to connect graphene layers and nanoparticles, which increases the conductivity of the material and makes the electron transfer easier. At the current density of 1 A g−1, the specific capacitance of the ZIF-67 composite is up to 5 times that of the ZIF-67. After alkali treatment, ZIF-67 is converted into Co(OH) 2 nanosheet (denoted as GO@Co(OH) 2 /PANI), which remarkably promotes the transfer of electrolyte ions and electrons. At the current density of 1 A g−1, the resulting specific capacitance is 15 times more than ZIF-67. The excellent energy storage performance indicates that the prepared novel composite material has important development prospects in energy storage. Image 1 • Simple & cheap. • GO@Co(OH) 2 /PANI, a new electrode material with special sandwich structure, applied for supercapacitors for the first time. • The specific capacitance of GO@Co(OH) 2 /PANI is up to 15 times that of the ZIF-67. • Excellent cyclic stability of GO@Co(OH) 2 /PANI (80%@20,000).. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 @Ni-MOF was prepared and alkalized to obtain MoS 2 /Ni(OH) 2. • MoS 2 /Ni(OH) 2 has high specific capacitance and long cycling life for supercapacitor. • MoS 2 /Ni(OH) 2 was used to construct electrochemical sensor for HQ and CC. A nickel-based metal-organic framework (Ni-MOF) layer was in situ grown on the surface of the sheet MoS 2 to synthesize MoS 2 @Ni-MOF as a precursor. In order to improve the properties of the precursor material, the final MoS 2 /Ni(OH) 2 material was obtained by alkalizing the precursor material. Supercapacitors and electrochemical sensors were prepared by MoS 2 /Ni(OH) 2 composite material. The test indicates that alkaline treatment of Ni-MOF materials is helpful to improve electrochemical performance. MoS 2 /Ni(OH) 2 material used as supercapacitor electrode has a high specific capacitance of 2192 F g−1 and excellent cyclic stability (the capacitance retention rate remains 85.19% after 10,000 charge/discharge cycles). The hybrid supercapacitor (HSC) was assembled with MoS 2 /Ni(OH) 2 as the positive electrode and activated carbon as the negative electrode. The MoS 2 /Ni(OH) 2 //AC HSC device shows an excellent energy density of 50.58 Wh kg−1 at the power density of 800 W·Kg−1. In addition, the MoS 2 /Ni(OH) 2 modified GCE electrode is an excellent electrochemical sensor for the simultaneous determination of hydroquinone (HQ) and catechol (CC). The modified electrode provides wide linear ranges of 1 ∼ 500 and 2 ∼ 400 μM and low detection limits of 0.43 and 0.48 μM for HQ and CC, respectively (S/N=3). The MoS 2 /Ni(OH) 2 material can be applied to supercapacitors and electrochemical sensors, indicating that the material has great potential application value in energy storage and biosensing. [ABSTRACT FROM AUTHOR]

• The novel Mn-Ni double hydroxide composite was prepared by alkalizing the Mn/Ni-MOF-74 precursor. • MnNiDH shows high specific capacitance and excellent retention rate. • The assembled aqueous and all-solid-state devices display high energy densities and wide voltage window. MOF-derived hydroxides provide a promising platform for high performance supercapacitors as electrode materials. Herein, a novel manganese-nickel double hydroxide (MnNiDH) composite with special morphology has been successfully prepared by alkalizing the precursor Mn/Ni-MOF-74. Obtaining electrode material inherits the spear-shaped morphology of the precursor well and possesses a smaller particle size by potassium hydroxide treatment. The smaller particle size and rich microporous structure can shorten the ion or proton transport path, thereby improve its electrochemical activity and utilization. Benefiting from these specific properties, the resultant MnNiDH composite demonstrates a high specific capacitance of 2498 F g−1 at a current density of 1A g−1. The assembled aqueous device exhibits high energy density of 58.53Wh kg−1, meanwhile the all-solid-state device also displays energy density of 30.63 Wh kg−1 based on the outstanding voltage window of 0∼2.1 V. These results suggest that as-synthesized MnNiDH hold great potential for practical applications in the energy storage field. [ABSTRACT FROM AUTHOR]

In this present paper, a novel layered multi-metal sulphide was reported as a positive electrode material with abundant electroactive sites and redox reaction centres. Molybdenum and sulfur elements were introduced into the metal-organic frameworks (M-MOF: M = Ni, Co and Ni/Co) to synthesize layered MMoS x by a hydrothermal method. The electrochemical performance comparison of MOFs and six electrode materials demonstrated that NiCoMoS x electrode materials had the best electrochemical performance and the highest specific capacitance. The highest specific capacitance could reach 2595 F g−1 at a current density of 1 A g−1. The NiCoMoS x electrode material also had an excellent cycle stability with a retention rate of 90.8% after 10,000 charge and discharge cycles. In addition, the as-assembled NiCoMoS x //AC assymmetric supercapacitor (ASC) device exhibited a maximum energy density of 48.2 Wh·kg−1 at a power density of 807.2 W kg−1, and the capacity retention rate after 10,000 charge and discharge cycles was 91.6%. This electrochemical performance indicated that this kind of material had a good market development prospect. • Six kinds of materials were synthesized by hydrothermal method to make working electrodes, and electrochemical properties were tested and compared. • It is proved that cobalt-nickel composite has higher specific capacitance and better electrochemical performance after molybdenum-doped vulcanization with MOF as precursor. • NiCoMoS x electrode material has good electrochemical properties and excellent cycling stability. • The assembled asymmetric supercapacitor has good energy storage and can light up red LED. [ABSTRACT FROM AUTHOR]

• The method of synthesizing the composite has been novel and has not been reported so far. • MoS 2 @Ni-MOF shows the remarkable specific capacitance. • The introduction of sulfur has established a bridge for the charge transfer. • The MoS 2 @Ni-MOF//AC ASC device exhibits a high energy density of 72.93 Wh kg−1 at power density of 375 W·kg−1. • The assembled all-solid-state MoS 2 @Ni-MOF//AC can illuminate commercial red LED lamps for up to 30 s. Two-dimensional metal-organic frameworks and nanoflowers of the MoS 2 form a composite structure as an electrode material for high-performance supercapacitor application. MoS 2 expands in the accordion-type Ni-MOF layers, and -S- joins the two materials to form a Ni-MOF coating MoS 2 composite structure. The composite material MoS 2 @Ni-MOF combines the structural characteristics of the Ni-MOF and MoS 2 , and effectively improves the electrochemical performance. The basic skeleton structure of the MoS 2 @Ni-MOF material remains unchanged, showing a remarkable specific capacitance of 1590.24 F·g−1 at a current density of 1.0 A·g−1 and an excellent cycle stability (retention rate of 87.97% after 20,000 cycles at current of 5.0 A·g−1). Due to the special composite structure of MoS 2 @Ni-MOF, the as-assembled MoS 2 @Ni-MOF//AC assymmetric supercapacitor (ASC) device exhibits a maximum energy density of 72.93 Wh·kg−1 at a power density of 375 W·Kg−1. These excellent electrochemical properties indicate that the MoS 2 @Ni-MOF has potential applications in energy storage devices. [ABSTRACT FROM AUTHOR]