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Abstract Metal sulfides have shown great potential as the anodes of the asymmetric supercapacitors ascribed to their superior theoretical specific capacitance. However, their specific capacitance and rate performances are still far from the expectation due to the intrinsic poor electronic conductivity and sluggish kinetics. Herein, we employ the anion and cation double‐substitution strategy to prepare iron sulfide nanoparticles on graphene composite (denoted as NiFeSP/G) to improve the electronic conductivity of FeS2. The NiFeSP/G composite exhibits greatly improved electrochemical performances with a high specific capacity of 765 C g−1 (765 F g−1) at 5 A g−1 and a remarkable rate capability of 65% at 100 A g−1. Moreover, an aqueous asymmetric supercapacitor is fabricated with the NiFeSP/G as anode and NiCo‐LDH/graphene as cathode presents an impressively high energy density up to 109 Wh kg−1 at 1591 W kg−1 and cycling performance (89% of the initial capacity retained after 8000 cycles).

Aqueous zinc (Zn)-based energy storage devices possess promising applications for large-scale energy storage systems due to the advantage of high safety, low price, and environment-friendliness. However, their development is restricted by dendrite growth and hydrogen evolution issues from the Zn-metal anode. Herein, a facile stress-pressing method is reported for constructing a grid zinc anode (GZn) with a conductive framework. The highly conductive copper (Cu)-mesh framework reduces electrode hydrogen evolution and increases electrode conductivity. Meanwhile, the in situ-formed Cu-Zn nano-alloy stabilizes the Zn deposition interface. As a result, the GZn symmetrical cell presents a low overpotential of 49 mV after cycling for 1,200 h (0.2 mA∙cm−2). In addition, GZn displays its potential application as a universal anode for Zn-ion capacitors and batteries. An activated carbon||GZn Zn-ion capacitor delivers a stable cycling performance after 10,000 cycles at 5 A∙g−1 and MnO2||GZn Zn-ion batteries exhibit satisfactory cycle stability and excellent rate performance. This demonstrates that GZn appears to be a promising universal anode for Zn-ion capacitors and batteries.

Abstract Graphite is the state‐of‐the‐art anode material for most commercial lithium‐ion batteries. Currently, graphite in the spent batteries is generally directly burned, which caused not only CO2 emission but also a waste of precious carbon resources. In this study, we regenerate graphite in lithium‐ion batteries at the end of life with excellent electrochemical properties using the fast, efficient, and green Flash Joule Heating method (FJH). Through our own developed equipment, under constant pressure and air atmosphere, graphite is rapidly regenerated in 0.1 s without pollutants emission. We perform a detailed analysis of graphite material before and after recovery by multiple means of characterization and find that the regenerated graphite displays electrochemical properties nearly the same as new graphite. FJH provides a large current for defect repair and crystal structure reconstruction in graphite, as well as allowing the SEI coating to be removed during ultra‐fast annealing. The electric field guide the conductive agent and binder pyrolysis products to form conductive sheet graphene and curly graphene covering the graphite surface, making the recycled graphite even better than new commercial graphite in terms of electrical conductivity. Regenerated graphite has excellent multiplier performance and cycle performance (350 mAh g−1 at 1 C with a capacity retention of 99% after 500 cycles). At cost, we get recycled graphite that displays the same performance as new graphite, costing just 77 CNY per ton. This FJH method is not only universal for the regeneration of spent graphite generated by various devices but also enables multiple use‐failure‐regeneration steps of graphite, showing great potential for commercial applications.

The transport performance of lithium ions affects the rate performance of the cathode at different current densities. The poor interface contact between a solid electrolyte and the cathode makes it difficult to transport lithium ions. Adding a solid electrolyte into the cathode material can improve lithium ion transport. In this paper, we prepared some cathodes with different doping ratios, including two common cathode materials (LiFePO4 and NCM811), and tested their rate and long cycle performance. LFP-10 has a specific discharge capacity of 79.75 mAh g−1 at 5C, and the Li+ diffusion coefficient of LFP-10 is 4.91 × 10−13 cm−2 s−1, which is about 13.4 times higher than the pure LiFePO4 sample. The rate performance of an all-solid-state battery has also been improved, and there is still more than 100 mAh g−1 capacity reserved at 60°C and 2C current density. This shows that the introduction of a PEGDA-based solid electrolyte can significantly improve the Li+ transport of the cathode, and the composite cathode also provides support for the future application of all-solid-state batteries.

Abstract Lithium‐sulfur batteries attract lots of attention due to their high specific capacity, low cost, and environmental friendliness. However, the low sulfur utilization and short cycle life extremely hinder their application. Herein, we design and fabricate a three‐dimensional electrode by a simple filtration method to achieve a high‐sulfur loading. Biomass porous carbon is employed as a current collector, which not only enhances the electronic transport but also effectively limits the volume expansion of the active material. Meanwhile, an optimized carboxymethyl cellulose binder is chosen. The chemical bonding restricts the shuttle effect, leading to improved electrochemical performance. Under the ultrahigh sulfur load of 28 mg/cm2, the high capacity of 18 mAh/cm2 is still maintained, and stable cycling performance is obtained. This study demonstrates a viable strategy to develop promising lithium‐sulfur batteries with a three‐dimensional electrode, which promotes sulfur loading and electrochemical performance.

Recently, the discharge of effluent containing dyes and other chemicals into river, lakes, and land has become a serious problem which increases the pollution level drastically. The dyes in the effluent are very difficult to be removed by conventional water treatment methods. Thus, there is a great need for more advanced methods that are cost-effective and more efficient. In this study, silver nano particles (AgNps) were synthesized by green method using extracts of onion (O), tomato (T), acacia catechu (C) alone, and mixed COT extracts. The reduction and formation of AgNps and its ions have been characterized by using several techniques, Ultra visible spectroscopy (UV–vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM)-energy dispersive X-ray spectrometer (EDX), Fourier transmission infrared spectroscopy (FTIR), and dynamic light scattering (DLS). These techniques revealed that the particle sizes of synthesized AgNps in all the extracts were ranged in between 5 and 100 nm with a crystalline nature. The synthesized AgNps were used as catalysts for the degradation of three different types of dyes, methyl orange (MO), methyl red (MR), and congo red (CR) in the liquid state. The excellent catalytic application of all the synthesized AgNps on the degradation of the studied dyes was confirmed via UV–visible results by studying the reduction in the absorbance maxima value within a very short interval of time. COT synthesized products were found to achieve the best performance for all dyes degradation among all products.

Abstract Sodium ion batteries and capacitors have demonstrated their potential applications for next-generation low-cost energy storage devices. These devices's rate ability is determined by the fast sodium ion storage behavior in electrode materials. Herein, a defective TiO2@reduced graphene oxide (M-TiO2@rGO) self-supporting foam electrode is constructed via a facile MXene decomposition and graphene oxide self-assembling process. The employment of the MXene parent phase exhibits distinctive advantages, enabling defect engineering, nanoengineering, and fluorine-doped metal oxides. As a result, the M-TiO2@rGO electrode shows a pseudocapacitance-dominated hybrid sodium storage mechanism. The pseudocapacitance-dominated process leads to high capacity, remarkable rate ability, and superior cycling performance. Significantly, an M-TiO2@rGO//Na3V2(PO4)3 sodium full cell and an M-TiO2@rGO//HPAC sodium ion capacitor are fabricated to demonstrate the promising application of M-TiO2@rGO. The sodium ion battery presents a capacity of 177.1 mAh g−1 at 500 mA g−1 and capacity retention of 74% after 200 cycles. The sodium ion capacitor delivers a maximum energy density of 101.2 Wh kg−1 and a maximum power density of 10,103.7 W kg−1. At 1.0 A g−1, it displays an energy retention of 84.7% after 10,000 cycles.

Abstract Lithium/potassium ion capacitors (LICs/PICs) have been proposed to bridge the performance gap between high-energy batteries and high-power capacitors. However, their development is hindered by the choice, electrochemical performance, and preparation technique of the battery-type anode materials. Herein, a nitrogen and phosphorus dual-doped multilayer graphene (NPG) material is designed and synthesized through an arc discharge process, using low-cost graphite and solid nitrogen and phosphorus sources. When employed as the anode material, NPG exhibits high capacity, remarkable rate capability, and stable cycling performance in both lithium and potassium ion batteries. This excellent electrochemical performance is ascribed to the synergistic effect of nitrogen and phosphorus doping, which enhances the electrochemical conductivity, provides a higher number of ion storage sites, and leads to increased interlayer spacing. Full carbon-based NPG‖LiPF6‖active carbon (AC) LICs and NPG‖KPF6‖AC PICs are assembled and show excellent electrochemical performance, with competitive energy and power densities. This work provides a route for the large-scale production of dual-doped graphene as a universal anode material for high-performance alkali ion batteries and capacitors.

We report a flash Joule heating method for the rapid preparation of graphene-like materials. The L-GHS exhibited a uniform diameter of 200 nm and an ideal specific surface area of 670 m² g-1. Meanwhile, the specific capacity of L-GHS remained at 942 mA h g-1 after 600 cycles (1 A g-1), which shows excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Mg-Li-Al-Sn and Mg-Li-Al-Sn-Ce alloys were prepared using a vacuum induction melting method. Their electrochemical oxidation behavior in NaCl solution was investigated by means of potentiodynamic and chronoamperometric measurements. The surface morphology after discharge was examined using scanning electron microscopy. Utilization efficiency was estimated with a mass-loss method. The results indicated that Mg-Li-Al-Sn has a higher discharge current density but lower utilization efficiency than Mg-Li-Al-Sn-Ce. The typical utilization efficiency after continuous discharging at constant potential of -1.0 for 2 h is 65% and 70% for Mg-Li-Al-Sn and Mg-Li-Al-Sn-Ce, respectively. The utilization efficiency decreased with the increase of anodic potential. Both alloys have similar self-discharge rate in NaCl solution at open-circuit potential. [ABSTRACT FROM AUTHOR]

Ni foam supported-Co3O4nanowire arrays are prepared by a template-free growth method, followed by a thermal treatment in air, and are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric and differential thermal analysis. The Co3O4nanowires have a diameter of about 250 nm, a length up to 15 μm, and a Brunauer-Emmett-Teller surface area of 78.4 m2g−1. They grow almost vertically from the surface of Ni foam skeleton, pack densely, and uniformly cover the entire surface of Ni foam skeleton. Electroreduction of H2O2on Co3O4nanowire arrays in alkaline medium is investigated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The Co3O4nanowire electrode exhibits superior activity, stability, and mass transport property for H2O2electroreduction. A current density of 90 mA cm−2is achieved at −0.4 V in 0.4 mol dm−3H2O2and 3.0 mol dm−3NaOH at room temperature. The per gram current density measured at −0.4 V on Co3O4nanowires is about 1.5 times of that on Co3O4nanoparticles. [ABSTRACT FROM AUTHOR]

Pd–Ru, Pd and Ru nanoparticles supported on Vulcan XC-72 carbon were prepared by chemical reduction of PdCl2 and/or RuCl3 in aqueous solution using NaBH4 as the reducing agent. Transmission electron microscopy measurements showed that Pd–Ru particles were uniformly dispersed on carbon. The particle size of Pd–Ru is around 5–9 nm. X-ray diffraction analysis indicated that Ru formed alloy with Pd in Pd–Ru/C catalyst. The electroreduction of hydrogen peroxide on Pd–Ru/C, Pd/C and Ru/C in H2SO4 solution was examined by linear sweep voltammetry and chronoamperometry measurements. Results revealed that Pd–Ru/C catalyst exhibited higher electrocatalytic activity for hydrogen peroxide reduction than Pd/C and Ru/C. All the catalysts showed good stability for hydrogen peroxide electroreduction in H2SO4 electrolyte. [ABSTRACT FROM AUTHOR]

Cobalt and manganese oxides ((Co, Mn)3O4) nanowires freely standing on nickel foam are prepared by a simple template-free growth process and heat treatment. The results show that the (Co, Mn)3O4 composite forms a uniform film and densely covers the nickel foam substrate. The film is composed of nanowires with a diameter up to around 30-40 nm. The electrochemical capacitance behavior of the self-supported binderless nanowires electrode is investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The (Co, Mn)3O4/Ni-foam electrode exhibits a high specific capacitance of 611 F g-1 at a charge/discharge current density of 2.38 A g-1 in 6.0 mol dm-3 KOH electrolyte. Furthermore, the (Co, Mn)3O4/Ni-foam electrode delivers a high energy density 13.6 Wh kg-1, and even a high power density of 5.68 kW kg-1. More importantly, the specific capacitance retention is 95% after 2000 charge/discharge cycles at 2.38 A g-1 and with columbic efficiency higher than 98%. This work suggests that the as-prepared (Co, Mn)3O4/Ni-foam electrode has potential application in electrochemical capacitors. [ABSTRACT FROM AUTHOR]

A new composite Ni electrode is simply prepared by electrodeposition of nano-scaled Ni particles onto multi-walled carbon nanotubes (MWNTs)-enabled conductive textile fiber (cosmetic cotton) which owns an especial three-dimensional (3D) network structure. The morphology and phase structure of the Ni-MWNTs-textile electrode are characterized by scanning electron microscope, transmission electron microscope and X-ray diffraction spectrometer, and the catalytic performance for the N2H4 electrooxidation is tested by linear sweep voltammetry and chronoamperometry. The results show that the Ni-MWNTs-textile electrode exhibits a remarkably high catalytic activity and good stability for N2H4 electrooxidation. The onset potential stays at around -0.9 V and the oxidation current density reaches as high as 12 mA cm-2 in the solution containing 1 mol dm³ NaOH and 20 mmol dm³ N2H4 at around -0.80 V, both of which outstrip the previous reports. [ABSTRACT FROM AUTHOR]

CuO/nitrogen-doped reduced graphene oxide (CuO/N-RGO) composites are prepared by refluxing in ammonia solution and low temperature annealing. The as-prepared samples have been characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The loading of CuO has been measured by using inductively coupled plasma mass spectroscopy (ICP-MS). Results reveal that the CuO nanoparticles with ∼5 nm in diameter are anchored homogeneously on the nitrogen-doped reduced graphene oxide (N-RGO) nanosheets. Their electrochemical performances for supercapacitors are investigated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The CuO/N-RGO composite with 15.1 wt% CuO loading shows a high specific capacitance of 340 F g-1 at a charge/discharge current density of 0.5 A g-1 in 6 mol dm-3 KOH electrolyte, and with a wide potential window of 1.4 V. Importantly, 58% of capacitance is retained when the charge/discharge current density increases from 0.5 A g-1 to 5 A g-1. The capacitance retention can reach to 80% after 500 charge/discharge cycles. These findings demonstrate that the CuO/N-RGO material is a promising candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Direct carbon fuel cell are promising power sources with their performance significantly depending on the anode reaction. In this study, the CeO2 prepared by a Sol-Gel method was investigated as the catalyst for the graphite electrooxidation in the molten alkali carbonate. Ceria and graphite powders with different mass ratios were first homogeneously mixed and then pressed into electrodes for the electrochemical measurements. Results indicated that the performance of graphite electrooxidation was remarkably improved by the addition of CeO2. The current density of the graphite electrooxidation with 50 wt.% ceria reaches 196 mA cm-2 at -0.4 V vs. Au/CO32-/O2,2CO2 and 750°C, which is considerably higher than that of pure graphite electrode (117 mA cm-2). The reaction mechanism relative to the ceria catalytic effect was explained by the indirect electrooxidation pathways via preceding chemical reactions following an electrochemical reaction. [ABSTRACT FROM AUTHOR]