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High entropy materials are becoming more and more popular in energy storage field of supercapacitors because of their unique structure and modulated functional characteristics, but their low conductivity and instability of electrode structure limit their further electrochemical performance. In this paper, we use polyethylene glycol (PEG) with different molecular weights to modify the surface morphology of the high entropy oxides (FeCoCrMnNi) 3 O 4 in an attempt to improve their supercapacitors performance. The PEG was used as a pore-making agent to prepare porous high entropy oxides powder with a large specific surface area of 92.7559 m2 g−1, providing more active sites and ion transport channels. A high specific capacitance of 204 F g−1 at 0.5 A g−1 and good cycle performance of 60.4 % capacitance retention after 10,000 cycles were obtained. Besides, an asymmetric device with improved energy density of 53 W h kg−1 and the power density of 400.8 W kg−1 were reached via the designed microstructure of the high entropy oxide electrode. [ABSTRACT FROM AUTHOR]

Among the existing electrochemical capacitive energy storage electrode materials, the (TiNbTaZrHf)C, (VCrNbMoZr) 2 N, (CoCrFeMnNi) 3 O 4 , (FeCoCrMnMg) 3 O 4 and (FeCoCrMnCuZn) 3 O 4 all have excellent capacitive performance, but the energy density is limited due to the narrow potential window. In order to solve the problem of low energy density of electrochemical supercapacitor, a kind of high-entropy carbides (HEMCs) with broad potential window is designed from generalized analysis of electrochemical window of active elements. This high-entropy carbide contains five active elements of Fe, Co, Cr, Mn and Ni. The prepared HEMC-3 has abundant pores and a specific surface area of 417.8 m2 g−1. The large specific surface area makes the HEMCs have high-rate energy storage performance. Electrochemical tests show that the HEMC-3 presents a potential window of [-1.0, 0.6] versus Hg/HgO, and can obtain a specific capacitance of 169.7 F g−1 at a current density of 0.5 A g−1. Due to the designed wide potential window of the prepared HEMCs, the energy density has been greatly improved, which shows a new strategy for developing of electrochemical supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

Stimulated by the pursuit of small and portable electronic devices, film supercapacitors have gradually developed. Due to the advantages of composition design and controllable performance, high entropy materials have shown excellent capacitive performance in electrochemical energy storage. Therefore, in this work, five transition metal elements Fe, Co, Cr, Mn and Ni were selected with different potential windows, and the (FeCoCrMnNi)C thin films with wide potential windows were successfully deposited on titanium and graphite substrates by using magnetron sputtering technology. The body centered cubic structured (FeCoCrMnNi)C films all have crystal orientation, showing irregular particle morphology, and the optimal orientation makes them eventually grow into morphologies similar to those of the substrates. The layered structure of the (FeCoCrMnNi)C film deposited on graphite substrate for 10 min is the most conducive to the storage of pseudocapacitance. We also found that (FeCoCrMnNi)C powder has better electrochemical properties than (FeCoCrMnNi)C film in the two low-dimensional states of the (FeCoCrMnNi)C, which is of great significance for exploring the development direction of supercapacitor electrode materials in the future. [ABSTRACT FROM AUTHOR]

Difunctional devices have great potential in the application of many areas, they can perform two functions simultaneously, and structural difunctional supercapacitor is one of them. The difunctional supercapacitor can carry out bearing capacity and storge electric energy, but it's difficult to keep the balance between bearing capacity and energy storage capacity. In this work, the montmorillonite based geopolymer has a compressive strength of 31.6 MPa after curing for 28 days, and a compressive strength of 30.5 MPa after repolymerization. We use the geopolymer as the framework, and inject 0.5 M Na 2 SO 4 into the geopolymer to prepared a structural electrolyte. Then, the structural electrolyte membrane, electrodeposited MnO 2 , and an activated carbon are assembled into a difunctional supercapacitor. The maximum specific capacity reaches 2216.7 mF cm−2 at 1 mA cm−2 under 15 MPa, achieving a good balance between compressive strength and energy storage capacity. [ABSTRACT FROM AUTHOR]

Abstract: Effects of ethanol supercritical drying treatment on morphology and electrochemical performance of DyBaCo2O5+δ (DBC), as cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs), was comparatively investigated. Powder samples were synthesized by EDTA–citric acid (EC) and ethanol supercritical drying assisted EDTA–citric acid (SCEC) techniques. The scanning electron microscopy (SEM) images show the particles synthesized by SCEC were smaller than those prepared by the EC method. The area specific resistance (ASR) value of SCEC-DBC as cathode was lower than that of DBC-EC cathode. The maximum power density of the single cell with SCEC-DBC cathode was higher than that of the cell with EC-DBC cathode in the investigated temperature range from 550 to 650°C. [Copyright &y& Elsevier]