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Cobalt manganese hydroxides with well-defined nanowire morphology (CoMn-HW) is scalable fabricated by adjusting solution contents, Mn/Co ratio and alkaline species. To further improve the conductivity of CoMn-HW, GO is introduced during fabrication process and reduced to rGO according to the high temperature and alkali atmosphere. By optimizing the adding mass of rGO, CoMn-HW/rGO with sandwiched like structure is successfully synthesized for supercapacitor electrode. The composite delivers a high specific capacitance of 784 F g−1 at current density of 0.5 A g−1, good rate capability (84.2% capacitance retention after current density increase 10 times). Moreover, an asymmetric supercapacitor with CoMn-HW/rGO10 as the positive electrode and active carbon as the negative electrode, is assembled and delivers a maximum energy density of 38.3 Wh kg−1 and power density of 8000 W kg−1, representing its potential in energy storage and conversion systems. • Co, Mn-hydroxides with nanowire morphology is scalable fabricated. • CoMn-HW/rGO with sandwiched like structure is synthesized under optimal synthesis condition. • An asymmetric supercapacitor based on CoMn-HW/rGO and AC is assembled with high energy and power densities. [ABSTRACT FROM AUTHOR]

[Display omitted] • OMC@NiO/Ni is synthesized via solvothermal reaction and subsequent calcination treatment. • "Trunk-leaf vein" structure endows OMC@NiO/Ni with superior electrochemical performance. • An asymmetric supercapacitor based on OMC@NiO/Ni and rGO/VO x as positive and negative electrodes respectively, is assembled. Supercapacitors are sustainable energy storage devices with the characteristics of high power density, long life span and ultrafast charge-discharge time. Herein, considering low conductivity of NiO and inspired by the "trunk-leaf vein" structure, mesoporous carbon and nickel dots are introduced into structure reacting as electron scaffold via facile hydrothermal and annealing procedures. Special hierarchical structure is obtained with oxygen modified mesoporous carbon (OMC) as core and NiO sheets as core accompanying with metallic nickel dots deposited on NiO sheets. Such "trunk-leaf vein" architecture can effectively ensure more active sites contacting with electrolyte, furthermore provide conductive scaffolds for electron transport. As expected, the OMC@NiO/Ni exhibits high specific capacitance of 651.3 F g−1 at 2 A g−1 and superior cycling life of 92.2% after 4000 cycles. Moreover, a novel negative electrode rGO/VO x is synthesized ascribe to the superior capacitance and life span. At last, an asymmetric device is assembled using OMC@NiO/Ni as positive electrode and rGO/VO x as negative electrode, which delivers maximum energy density of 44.3 Wh kg−1, high power density of 12,000 W kg−1 and excellent cycling life of 94.5% after 5000 cycles. The high performance of OMC@NiO/Ni renders it a potential material for energy storage-conversion equipments. [ABSTRACT FROM AUTHOR]

Potassium ion batteries or capacitors are a promising technology for large-scale energy storage due to the abundant resource and low cost of potassium. However, the development of stable electrode materials with high capacity, capable rate ability, and excellent cycling stability remains a challenge. Herein, carbon dots modified reduced graphene oxides (LAP-rGO-CDs) are designed and synthesized via a rapid and green microwave-assisted method with l -Ascorbic acid 6-palmitate (LAP) as the reducing agent. LAP-rGO-CDs present enlarged interlayer spacing and faster ion transfer rate owing to the introducing of carbon dots. Serving as a potassium ion battery electrode, LAP-rGO-CDs showed a high specific capacity of 299 mAh g−1 at 1 A g−1 and excellent cycling stability. Moreover, a LAP-rGO-CDs//AC full carbon-based potassium ion capacitor is assembled and displays a maximum energy density of 119 Wh kg−1 and a power density of 5352 W kg−1. This work demonstrates the potential application of LAP-rGO-CDs for high-performance potassium ion storage. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Defective graphene with high density of defects is prepared via Flash Joule Heating. • An ultrahigh reversible capacity of 2450 mAh g−1 is achieved for defective graphene. • Nascent defects, lithium plating and 3D structure contribute to the high capacity. • Excess lithium storage and fading mechanisms are revealed. • Insights for designing high-capacity electrodes based on defect engineering. Introducing defects is an effective approach to promote the lithium ion storage ability of host material. Constructing pure defects is beneficial to understand the lithium ion storage mechanism in the defects. Herein, we fabricate defective graphene without intricate functional groups via a flash Joule heating (FJH) technique within a mere 1 ms. The FJH-reduced graphene lattice harbors a multitude of defects, and its unique three-dimensional structural network enables an ultra-high lithium ion storage capacity. Moreover, the highest capacity of F-RGO-5 reaches 2500 mAh/g in the 800th cycle, its three-dimensional architecture allows it to withstand high currents and prolonged cycles without drastic failures. Nascent defects and defect-induced lithium plating predominantly contribute to capacity enhancement during cycling, while dendrite formation primarily leads to decay. Our findings present an approach to defect-based designs of high-capacity lithium anodes and provide valuable insights into their energy storage mechanisms. [ABSTRACT FROM AUTHOR]

Highlight • A two-step hydrothermal strategy is adopted to transform Ni 3 [Fe(CN) 6 ] 2 to NiFe 2 O 4. • NiFe 2 O 4 @rGO slice is prepared as electrode for flexible symmetric supercapacitor. • NiFe 2 O 4 @rGO electrode shows excellent specific capacitance and cycling stability. Abstract A high working voltage and specific capacitance are vital for flexible solid-state symmetric supercapacitor (FSSC) devices to achieve decent energy densities with high power. In this paper, we report a 1.8 V FSSC based on NiFe 2 O 4 nanocubes anchored on reduced graphene oxide (rGO) cryogel electrode. Through surface protection by a free-standing three-dimensional cross-linked network structure, NiFe 2 O 4 converted from Ni 3 [Fe(CN) 6 ] 2 inhibits the original nanocube structure. Benefiting from the synergistic effects between NiFe 2 O 4 nanocubes and graphene nanosheets, the newly synthesized NiFe 2 O 4 @rGO hybrid electrode delivers a high charge storage capacity (488 F g−1 at a constant current density of 1 A g−1), excellent rate ability and cycling performance (89.8% of the initial capacitance value after 10,000 cycles). In addition, NiFe 2 O 4 @rGO FSSC has been assembled and exhibits stable behavior at bend state, as well as high energy density of 62.5 Wh kg−1, and long cycle life (93.2% of the initial capacitance value after 6000 cycles). The proposed strategy for controlling the design and synthesis of NiFe 2 O 4 @rGO nanostructures provides promise for the development of high performance electrode in advanced energy storage devices. [ABSTRACT FROM AUTHOR]

Graphical abstract The super-ionic conductivity nanowire Cu 2 Se/Ni-foam electrode processes excellent cycling performance and the electrode is firstly assembled to asymmetric supercapacitor achieving high energy and power density. Abstract Transition metal selenide has stimulated much research interest in energy storage and conversion, due to its excellent electrical conductivity. β-Cu 2 Se with special crystal structure is considered as super-ionic conductor, of which the diffusion coefficient is as large as a liquid. The fast ions and electrons conductor β-Cu 2 Se with uniformly dense nanowire crossing with each other directly on nickel foam is prepared via simple one-step solvothermal grow method for 4 h, avoiding conductive agent and binder. The feature much benefitting for electrons and ions transfer enable the β-Cu 2 Se-4h electrode delivers specific capacity as high as 182.4 mA h g−1 at current density of 2 mA cm−2, which is still 105.6 mA h g−1 even at high current density of 50 mA cm−2, and excellent cycling stability of 85% after repetitively charge-discharge 10,000 times. The fabricated asymmetric supercapacitor (β-Cu 2 Se-4h//AC) achieves maximum energy and power density is 48 Wh kg−1 and 5500 W kg−1. [ABSTRACT FROM AUTHOR]

Abstract In this work, activated carbon tube bundles (ACTBs) with porous hollow structure are prepared using dandelion fluffs as precursors. The open-framework porous structure of the ACTBs contributes to large specific surface area and enhanced electrochemical performances. Then the ACTBs are further modified with polyaniline (PANI) using the in-situ polymerization method, the unique hollow tube structure of the ACTBs effectively increases the growth area for the PANI. The PANI modified ACTBs (PANI/ACTBs) composite exhibits an excellent rate performance due to the highly retained porous hollow tube structure, which promotes the electrolyte ions diffusion and electron transport. Meanwhile, the ACTBs and PANI/ACTBs serve as the cathode and anode electrode materials for asymmetric supercapacitor, respectively. As a result, the asymmetric supercapacitor displays a high energy density of 42 Wh kg−1 and a capable cycling stability. These results demonstrate that the PANI/ACTBs composite is a promising electrode material for the energy storage devices. Graphical abstract Image 1 Highlights • The porous structure of the ACTBs contributes to the enhancement of the specific surface area and cycling stability. • The ACTBs can solve the aggregation problem and provide more space for the volume changes of the PANI particles. • The PANI/ACTBs exhibits high capacitance and the good cycling stability due to the combined advantages of PANI and ACTBs. • The PANI/ACTBs composite exhibits high energy density of 42 Wh kg−1. [ABSTRACT FROM AUTHOR]

In this work, for the first time, we design a high-energy-density double-chamber capacitor which consists of the cathode chamber (polyaniline@carbon fiber cloth electrode in HCl/FeCl 3 solution), anion-exchange membrane and the anode chamber (polyaniline@carbon fiber cloth electrode in HCl/FeCl 2 solution). Since the redox state of polyaniline can be continuously altered by the external potential during charging and discharging process, the addition of FeCl 3 (or FeCl 2 ) in the electrolyte works as chemical oxidant (or reductant) to oxidize (or reduce) the reduced (or oxidized) polyaniline to offer extended capacitance. Results show the double-chamber supercapacitor has a high area specific capacitance of 1.22 F cm −2 and an energy density of 108.44 μWh cm −2 , which are ∼3.5 times as large as those of the conventional single-chamber capacitor (0.35 F cm −2 / 31.11 μWh cm −2 ). This work demonstrates an innovative strategy by incorporating supercapacitor with fuel cell to improve the energy density. [ABSTRACT FROM AUTHOR]

The 1D nanowire is prepared by in-situ etching current collector displaying faster electron transportation and better connection, plusing the directional charge transport properties, which could enable it become one of the most appropriate core of 3D core@shell structure. We apply novel nanowire-like Cu(OH) 2 , which is synthesized by etching copper foil, as core structure to be coated by novel NiOOH with high theoretical capacity. The fast electronic conductive core structure and promising faradic electrode material candidate material enable the Cu(OH) 2 @NiOOH/copper-foil electrode deliver high specific capacity of 1300 C g −1 at current density of 10 mA cm −2 and outstanding cycling stability of capacity retention of 88% after 10000 charge-discharge cycles, indicating the as-prepared Cu(OH) 2 @NiOOH/copper-foil electrode has potential application in electrochemical capacitors. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable magnesium-ion batteries with low cost of magnesium resources have a potential to meet growing requirements for electric energy storage resulted from the similar electrochemical properties to lithium. The Mg 1.1 Mn 6 O 12 ·4.5H 2 O named as magnesium octahedral molecular sieves (Mg-OMS-1) owns nanobelt structures as a cathode material for aqueous magnesium-ion battery. The morphology and structure of Mg-OMS-1 are measured by X-ray diffraction, scanning and transmission electron microscopy. The mechanism of magnesium-ion insertion/deinsertion from this host material and the theory specific capacity of Mg-OMS-1 are determined by cyclic voltammetry, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Mg-OMS-1 displays an excellent battery behavior for Mg 2+ insertion and deinsertion in the magnesium-salt aqueous electrolyte. The initial discharge capacity of Mg-OMS-1 electrode can reach 248.8 ± 0.5 mAh g −1 at 10 mA g −1 in the 0.2 mol dm −3 Mg(NO 3 ) 2 aqueous electrolyte. Even back to 10 mA g −1 after the rate performance, the discharge capacity can achieve 214.1 ± 0.5 mAh g −1 . The specific capacity retention rate is 90.4% after cycling 200 times at 100 mA g −1 in the 0.5 mol dm −3 Mg(NO 3 ) 2 electrolyte with a columbic efficiency of 99.7 ± 0.1% in the 5 times experiments. [ABSTRACT FROM AUTHOR]

Ni(OH) 2 has been reported widely as one of the most promising supercapactior electrode materials due to its high specific capacitance, yet which were only based on low mass loading. Thus, it is desirable to promote supercapacitor performance for high mass loading Ni(OH) 2 through optimizing microstructure. In this work, we first prepared crossed ultrathin Ni(OH) 2 /ZnO nanoleafs directly grown on nickel foam via hydrothermal method, and then we produced pores on the nanoleafs by dissolving ZnO in alkaline solution. Definitely, this unique structure design for high mass loading binder-free Ni(OH) 2 electrode could benefit the penetration of electrolyte and the transportation of electrons, efficiently improving the supercapacitor performance. The obtained porous Ni(OH) 2 /NF electrode exhibits a mass specific capacity of 1142C g −1 based on 10 mg active materials, equating to a areal specific capaciy of 11.4C cm −2 , and pleasant cycling stability with retention of 85% of initial capacity after 10000 charge-discharge cycles. The fabricated asymmetric device shows a high energy density of 42 Wh kg −1 (4.73 mWh cm −3 ) at power density of 105 W kg −1 (17 mW cm −3 ). These results demonstrate the optimized structure makes the high mass loading binder-free Ni(OH) 2 /NF electrode could also display excellent supercapacitor performance. [ABSTRACT FROM AUTHOR]

Facile in-situ etching current collector prepares corresponding oxide or sulfide, which is directly used as faradic electrode material, supplying faster electron transportation and better connection, and thus displaying good supercapacitor performance. Here, we prepare Cu x S via etching copper foam and investigate the influence of etching time on the morphology and electrochemical performance. The results show that compared with the nano-rod Cu x S-1h/CF, nano-rod/wire Cu x S-2h/CF and block/nanorod Cu x S-4h/CF, the nano-rod/ribbon Cu x S-3h/CF electrode exhibits the highest specific capacity (448.8C g −1 at current density of 5 mA cm −2 ). We fabricate asymmetric supercapacitor based on Cu x S-3h/CF as positive electrode and AC as negative electrode to further evaluate the supercapacitor property and the device achieves a high energy density of 35 Wh kg −1 at power density of 266 W kg −1 . Furthermore, the outstanding cycling stability of 88% capacitance retention after 5000 charge-discharge cycles more enable the Cu x S-3h/CF become promising faradic electrode material. [ABSTRACT FROM AUTHOR]

Herein, Polypyrrole was used as the conductive wrapping material electro-deposited on the MnO 2 nanoflakes covered on C/TiO 2 nanowire arrays to form PPy@MnO 2 @C/TiO 2 double shell/core structured arrays electrode for supercapacitor. Their structure and surface morphology were studied by using X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. The results suggest that a thin layer of PPy was successfully wrapped on the surface of MnO 2 , and the shell/core structure of MnO 2 @C/TiO 2 nanowire arrays was not changed after electro-deposition of PPy. The electrochemical tests indicate that the PPy@MnO 2 @C/TiO 2 double shell/core arrays electrode exhibits high specific capacitance of 715 F g −1 at a charge/discharge current density of 1 A g −1 and improved specific capacitance retention to 84.0% after 1000 cycles. These results show that the unique three dimensional (3D) double shell/core structured electrode holds promise for high-performance energy storage devices. The superior capacitive perfomance may due to the unique 3D C/TiO 2 nanowires and the unique double shell/core structures. Firstly, the 3D C/TiO 2 nanowire arrays, as excellent platform for loading active materials, can facilitate the permeation of electrolyte. Moreover, the thin layer PPy tightly wrapped on the MnO 2 nanoflakes can improve the electrical conductivity of MnO 2 . Therefore, the PPy@MnO 2 @C/TiO 2 electrode is promising candidate for electrochemical energy applications. [ABSTRACT FROM AUTHOR]

A high-performance capacitor battery AC/ λ -MnO 2 based on Na-ion insertion-deinsertion into λ -MnO 2 in 1 mol dm −3 Na 2 SO 4 solution is successfully demonstrated. A simple acid leaching technique is used to produce λ -MnO 2 by treating LiMn 2 O 4 with H 2 SO 4 . X-ray power diffraction and inductively coupled plasma analysis provide supporting evidences for the extraction of Li + from the LiMn 2 O 4 , and the particle morphology of λ -MnO 2 is studied by scanning and transmission electron microscopy. A high specific capacity of 390.7 mAh g −1 is obtained for the λ -MnO 2 electrode at a current density of 13.6 mA g −1 with a nearly 100% efficiency. The capacitor battery AC/ λ -MnO 2 can operate at a cell voltage as high as 2.2 V, and it exhibits a specific energy of 19.7 Wh Kg −1 at a high power density of 3500 W Kg −1 and a high energy density of 71.7 Wh Kg −1 at a low power density of 403 W Kg −1 . It has potentials to be used as an energy storage device for the integration of solar and wind power into the electrical power grid. [ABSTRACT FROM AUTHOR]

Highlights: [•] MnO2/C/TiO2 shell/shell/core arrays electrode has been prepared by simple thermal reaction and electrodeposition method. [•] The unique shell/shell/core structure has easy access of electrolyte ions, large surface to volume and high electrochemical activity. [•] The MnO2/C/TiO2 shell/shell/core arrays exhibits high specific capacitance of 639 F g−1 at a charge/discharge current density of 1 A g−1. [ABSTRACT FROM AUTHOR]

• α-MnSe Nanosheets are prepared via a facile hydrothermal method. • The effect of reaction time on electrochemical performance is investigated. • The α-MnSe electrode delivers a high capacity of 88.3 mAh g−1 at 1 A g−1. • The asymmetric supercapacitor exhibits a high energy density of 39.3 Wh kg−1. Transition metal selenides are regarded as emerging materials for energy storage devices because of their good electrical conductivity and electrochemical activity. Here, a binder-free ultrathin α-MnSe nanosheets electrode is prepared and the supercapacitor performance is comprehensively explored. Due to the increased active sites, enlarged contact area for electrolyte, as well as shorten ions diffusion pathway, the prepared electrode delivers high capacity of 88.3 mAh g−1 at 1 A g−1, good rate capability, and long-term durability (91% remain after 5000 cycles). Moreover, the asymmetric supercapacitor, fabricated by α-MnSe anode and active carbon cathode, displays a high energy density of 39.3 Wh kg−1 at a power density of 0.92 kW kg−1 and satisfying cycle performance. This study demonstrates that the binder-free α-MnSe electrode holds great promise for supercapacitor. [ABSTRACT FROM AUTHOR]

Developing novel materials with rational structures and excellent electrical conductivity is vitally important for energy storage devices. Herein, hollow cobalt molybdenum selenide (Co–Mo–Se) nanosheet arrays are fabricated via a self-sacrificing template method and selenization process, where cobalt-organic framework serves as the template. Benefiting from unique hollow nanoarrays structure, the Co–Mo–Se electrode offers rich electroactive sites, large accessible regions for electrolyte, and short ions diffusion pathways. Additionally, it is observed that the Co–Mo–Se possesses a low charge transfer resistance owing to the intrinsic metallicity. As a result, the Co–Mo–Se electrode exhibits favorable energy storage properties, including high capacity (221.7 mAh g−1), good rate property, and outstanding stability (95% after 8000 cycles). More importantly, the assembled Co–Mo–Se//active carbon (AC) achieves high energy density (44.7 Wh kg−1) and remarkable durability. Notably, two hybrid devices connected in series successfully power an electronic watch for 70 min, demonstrating its practical applicability. These results indicate that the synthesized hollow Co–Mo–Se nanosheet arrays have promising applications as electrode materials for high-performance energy storage devices. • Co-MOF was employed as template to obtain hollow Co–Mo–Se nanosheet arrays. • The Co–Mo–Se delivers a specific capacity of 221.7 mAh g−1 at 1 A g−1. • The ion exchange/etching method was applied in this work. • The asymmetric supercapacitor delivers high energy and power densities. [ABSTRACT FROM AUTHOR]

• CoSe 2 /RGO composite were prepared via a facile microwave assisted method. • The effects of RGO content on electrochemical performance were investigated. • The CoSe 2 /RGO-3 electrode delivers high capacitance of 761 F g−1 at 1 A g−1. • The CoSe 2 /RGO-3//AC exhibits high energy density of 43.1 Wh kg−1 at 800 W kg−1. The composites composed of metal selenides and carbonaceous materials have revealed enormous potential in varied applications. Herein, CoSe 2 /reduced graphene oxide (CoSe 2 /RGO) composites are prepared by a low-cost and efficient microwave assisted method. The effects of RGO proportion on crystalline structure, microstructure and energy storage capacity are explored. Benefiting from the good electrical conductivity and reasonable RGO content, the CoSe 2 /RGO sample with 35.2 wt% RGO reveals an excellent specific capacitance of 761 F g−1 as well as outstanding durability. More importantly, we construct an all solid-state hybrid supercapacitor (CoSe 2 /RGO//active carbon) to broaden the voltage window, resulting in an enhanced energy density (43.1 Wh kg−1). The hybrid device presents a favorable durability with 10% capacity drop after 10,000 cycles. In addition, the practical applicability of asymmetric device is confirmed by powering a blue light emitting diode (LED) for more than 10 mins. This work presents a simple, effective, and reasonable construct strategy to synthesize composites of selenides and RGO for charge storage application. [ABSTRACT FROM AUTHOR]

Bimetallic metal selenides have gained increasing attention as potential electrode materials for energy storage systems owing to good electrical conductivity and superior electrochemical activity. Herein, the Ni x Co y Se 2 (x+y=1) electrodes are prepared by a facile and rapid electrodeposition process. The electrochemical performance is optimized via adjusting the ratio of Co and Ni. It is turned out that equivalent Co and Ni in the composite (Ni 1/2 Co 1/2 Se 2) shows the best supercapacitor performance, including high specific capacity (166.1 mAh g−1) and long-term stability. Moreover, Density Functional Theory (DFT) calculation confirms the covalent interaction between nickel and cobalt, implying the existence of synergistic effect. To assess the practical value of the rationally designed Ni 1/2 Co 1/2 Se 2 electrode material, an asymmetric supercapacitor device is fabricated (Ni 1/2 Co 1/2 Se 2 //AC), which delivers a high energy density of 46.0 Wh kg−1 at 1141 W kg−1, coupled with 9.8% capacity loss after 10000 cycles. Notably, the low-voltage setups (LED and electric fan) can be easily activated by two devices in series, further demonstrating the great potential for practical application of Ni 1/2 Co 1/2 Se 2 electrode. [ABSTRACT FROM AUTHOR]

Flexible electrochemical energy storage devices have great potential in wearable and portable electronic devices. However, their practical applications have been deferred by mechanical damages such as repeated stretching, bending and squeezing. Self-healing hydrogel electrolytes can automatically repair such physical damages and maintain good electric contact at electrode/electrolyte interface. Herein, we report a hydrogel electrolyte with excellent tensile properties and good conductivity under large strain/stress. A solid state supercapacitor was further demonstrated, showing a high energy density of 21.3 Wh kg-1 at a power density of 350 W kg-1. The as-fabricated supercapacitor possesses good stretchability, with a 68% of retention of its initial capacitance after 40 breaking/healing cycles. The excellent self-healing capability of the hydrogel electrolyte can be attributed to the presence of hydrogen bonds and molecular chain fluidity within its structural motif. Our work provides promising routes towards developing new self-healing solid-state electrolytes for next-generation electrochemical energy storage and conversion applications with good performance and high safety. [ABSTRACT FROM AUTHOR]

• Ultrathin in-plane 1T-2H MoS 2 heterostructures are coaxially arrayed on 3D CFs. • The 1T-2H ultrathin heterostructures exhibit surprising structure stability. • Our ASC device exhibits an ultrahigh energy density of 81.4 Wh kg−1. Metallic 1T MoS 2 is a promising anode candidate for supercapacitors due to its intrinsically excellent electrical conductivity and high electrochemical activity. However, it is quite unstable and hard to be massively synthesized through common methods. Herein, structurally stable ultrathin (1–3 layers) in-plane 1T-2H MoS 2 heterostructures have been rationally modulated and coaxially aligned on three-dimensional carbon nanofibers (MoS 2 /CF) through a facile hydrothermal approach for supercapacitors and electrocatalysis. Benefiting from the unique heterostructure, the MoS 2 /CF composite shows amazing stability with no obvious change after being stored in air for over 36 months. In addition, it presents high specific capacitance of 310 F g−1 and remarkable rate capability of 78% at 100 mV s−1. The fabricated asymmetric supercapacitor delivers an impressive energy density of 81.4 Wh kg−‍‍‍‍‍1 in 1 M Na 2 SO 4 solution attributed to the high specific capacitance and large operating voltage range of 2 V. Moreover, the MoS 2 /CF composite also demonstrates enhanced electrocatalytic activity for hydrogen evolution reaction with a low overpotential of 194 mV at 10 mA cm−2. The work may promote the developments of high-performance bifunctional energy conversion and storage systems in future. [ABSTRACT FROM AUTHOR]

As a mainstream energy storage device, lithium-ion batteries have always been the focus of scientific researchers. As the most promising anode material, lithium metal has the advantages of high capacity and low reduction potential. Unfortunately, lithium dendrites can cause serious safety hazards during cycling. In this study, biomass carbon with a large number of straight holes was embedded with nickel particles as the anode framework. Nickel induces lithium to complete nucleation and growth in the pores and inhibits dendrite growth. Solid electrolyte interface (SEI) film growth, dead lithium, and electrode breakage all occur within the holes to a limited extent. Benefited from this internal reaction, the electrode obtains better electrochemical and cycling performances. The nickel-modified electrode was stably cycled for 1370 h at a current density of 5 mA/cm2 with a capacity of 2 mAh/cm2. Moreover, more massive capacity lithium storage (5 mAh/cm2) was tried, and the cycle was stable for 630 h. Using the same biomass carbon matrix, the pores were filled with sulfur powder as the positive electrode. After 100 periods of the full cell operation, the capacity retention rate is 85%. [ABSTRACT FROM AUTHOR]

• Low-cost MgFe x Mn 2-x O 4 nanoparticles were prepared via a facile so-gel route. • MgFe 1.33 Mn 0.67 O 4 exhibited good rate ability and cycling stability. • MgFe 1.33 Mn 0.67 O 4 displays Mg-ions diffusion coefficients of 2.55 × 10−7 cm2 s−1. Aqueous Mg-ion batteries attract lots of attention due to its high safety, low cost and potential application for large scale energy storage system. Although spinel-type metal oxides display their capable Mg ions storage behavior, low diffusion ability extremely hinder their practical application. Herein, low-cost MgFe x Mn 2-x O 4 (x = 0.67, 1, 1.33, 1.6) nanomaterials are prepared by a facile sol–gel method. Their electrochemical performance is affected by molar ratio of iron to manganese. The optimized MgFe 1.33 Mn 0.67 O 4 exhibits excellent electrochemical cycling performance and rate capability. Even at high current density of 1000 mA g−1, a specific capacity 88.3 mAh g−1 is obtained after 1000 charge–discharge cycles. The stable structure of MgFe 1.33 Mn 0.67 O 4 promise a cycling stability. Moreover, hydrogen evolution and oxygen evolution of the electrode material during charging-discharging process can be effectively suppressed by regulating the atom ratio of iron to manganese. In addition, it presents a high magnesium diffusion coefficient at two oxidation peaks, leading to a good rate ability. [ABSTRACT FROM AUTHOR]

• The human hair with high elasticity capable can serve as a promising flexible supporter for the electrode. • The reduced graphene oxide nanosheets can effectively improve the electrical conductivity of the electrode. • The Ni(OH) 2 nanoribbon-intercalated rGO nanosheets shows an interconnected porous structure. • The solid-state flexible supercapacitor delivers high energy density and good cycling stability. The demands for wearable energy storage devices keep growing and novel flexible electrode materials and facile prepared methods for these devices are crucial and attractive. In this work, human hair fiber is employed as the flexible fiber-based material due to the high utilization values of low cost, controllable length and high elasticity capable. Herein, an effective and hazard-free microwave-assisted method is reported to develop superelastic reduced graphene oxide coating human hair (rGO@Hh) to achieve conductive and high-strength fibrous electrode. With the braided rGO@Hh fibers, nickel hydroxide nanoribbon-intercalated rGO nanosheets (Ni(OH) 2 /rGO@Hh) are further prepared through microwave radiation treatment, which shows an interconnected porous structure with outstanding electrochemical performances of high specific capacitance (316 F g−1 at 1 A g−1) and good cycling performance. Moreover, a solid-state fiber-based asymmetric supercapacitor (FASC) is assembled with rGO@Hh fibers and Ni(OH) 2 /rGO@Hh fibers as negative and positive electrodes, which demonstrates a high energy of 27.6 Wh kg−1 and a power density of 699 W kg−1, respectively. The FASC also can be further used for numerous electronic products, presenting its prospect for portable wearable devices with high tensile strength and excellent performances. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous aluminum ion batteries (RAAB) have gained increasing attentions for large scale energy storage system due to their high safety, nontoxicity and low cost. However, lack of capable anode materials extremely hinders their potential application. As we all know, the anodic material of aluminum ion battery was limited, we report poly (3,4,9,10-perylentetracarboxylic diimide) (PPTCDI) under the different synthesis conditions as organic anode material for aqueous RAAB. The aluminum ions intercalation/deintercalation storage mechanism is affected by the different electrolyte concentrations. Upon their high capacity and cycling stability, our work would highlight potential application of conjugated polymer organic electrode materials for aqueous aluminum ion batteries. Unlabelled Image • The PPTCDI as anode in aqueous Al-ion battery was reported for the first time. • The Al-ion battery delivers excellent electrochemical cycling stability. • The aluminum ions intercalation/deintercalation storage mechanism is affected by the different concentrations of electrolyte. [ABSTRACT FROM AUTHOR]