There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).

A review of electrolyte materials and compositions for electrochemical supercapacitors

EVOLUTION: Of Mice . . .

One-dimensional carbon nanotubes and two-dimensional graphene nanosheets with unique electrical, mechanical and thermal properties are attractive reinforcements for fabricating light weight, high strength and high performance metal-matrix composites. Rapid advances of nanotechnology in recent years enable the development of advanced metal matrix nanocomposites for structural engineering and functional device applications. This review focuses on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets. These include processing strategies of carbonaceous nanomaterials and their composites, mechanical and tribological responses, corrosion, electrical and thermal properties as well as hydrogen storage and electrocatalytic behaviors. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel nanocomposites.

Recent progress in the development and properties of novel metal matrix nanocomposites reinforced with carbon nanotubes and graphene nanosheets

Electrolytes are one of the vital constituents of electrochemical energy storage devices and their physical and chemical properties play an important role in these devices' performance, including capacity, power density, rate performance, cyclability and safety. This article reviews the current state of understanding of the electrode–electrolyte interaction in supercapacitors and battery–supercapacitor hybrid devices. The article discusses factors that affect the overall performance of the devices such as the ionic conductivity, mobility, diffusion coefficient, radius of bare and hydrated spheres, ion solvation, viscosity, dielectric constant, electrochemical stability, thermal stability and dispersion interaction. The requirements needed to design better electrolytes and the challenges that still need to be addressed for building better supercapacitive devices for the competitive energy storage market have also been highlighted.

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Electrolyte selection for supercapacitive devices: a critical review

This aim of this study was to investigate the tribological properties of a self-lubricating Ni–P–polyfluorotetraethylene (PTFE) composite coating prepared by the electroless plating method. The effects of PTFE contents in the coating, load and rotation speed on the tribological behaviors were evaluated using a ring-on-disk wear machine. The results show that there was a distinct decrease in the average value of the friction coefficient from 0.33 to 0.12 at 70 N with an increase in PTFE content from 4.2 to 15.2 wt%. The coating of Ni–P–4.2 wt% PTFE had good antifriction and wear properties at a load of 30–70 N, and that of Ni–P–10.6 wt% PTFE had passable wear resistance and better antifriction at <50 N. Antifriction and wear mechanisms of Ni–P–PTFE are discussed in detail based on the results from micrograph and element analyses of the worn surface, subsurface stratum and wear debris analysis by scanning electronic microscopy (SEM), and energy-dispersive X-ray analysis (EDAX), respectively. The lubricating film (LF) generated during wear played a key role in the antifriction effect, which in turn was dependent on the integrity and thickness of the film determined by the PTFE concentration and wear conditions. The formation, fracture, and delamination course of the LF during wear were also analyzed and characterized.

Antifriction and Wear Characteristics of Electrolessly-Deposited Ni–P with PTFE Composites

In this work, the effects of elastic and plastic deformations on corrosion of an aluminum bronze alloy in 3.5% NaCl solution were investigated by mechanical testing, electrochemical measurements, and mechanoelectrochemical numerical analysis. Results demonstrate that the effect of stress/strain on corrosion of the alloy depends on the type of the induced elastic or plastic deformation. Elastic deformation resulting from application of elastic stresses would not affect (increase) appreciably the corrosion activity of the alloy. However, plastic deformation resulting from application of plastic pre-strain enhances the corrosion activity of the alloy significantly. Thus, the mechanoelectrochemical effect on the alloy corrosion is negligible under elastic deformation, but it is great at the plastic deformation stage.

Effects of Elastic and Plastic Deformations on Corrosion of an Aluminum Bronze Alloy in NaCl Solution

To improve the magnetic properties, nickel hollow spheres (NHSs) were surface-modified with a cellular Co structure by a facile electroless cobalt plating route. The microstructures and properties of the modified NHSs were characterized by field emission scanning electron microscopy, x-ray diffraction, Brunauer?Emmett?Teller specific surface area and a vibrating sample magnetometer. Microwave properties were evaluated by mixing NHSs with polyvinyl butyral as coaxial samples. The SEM images showed that the NHSs were coated by the Co cellular films, which not only increased the specific surface area but also enhanced the coercivity and magnetization. Also, the modified NHSs composites presented low RL min values below ?30?dB at thicknesses between 1.0 and 2.0?mm, and exhibited a broad absorption bandwidth ?W at 'thin' thickness.

https://iopscience.iop.org/article/10.1088/0022-3727/42/15/155002/pdf

Surface-modified micrometre nickel hollow spheres and their microwave characteristics

Preparation of submicron-sized cuprous oxide crystallites by electrodeposition with polyethylene glycol as additive

The composite electroforming process of preparing nanometer alumina particle reinforced copper base composite material has phosphor copper plate as anode material, stainless steel sheet as cathode deposition body, nanometer level alumina particle as reinforcing particle, and fluorocarbide surfactant or formamide as co-deposition promoter. Through mixing alumina particle and co-deposition promoter solution through stirring, pouring the mixed solution into electroforming solution of copper sulfate, applying DC voltage while stirring the electroforming solution to make copper ion and reinforcing particle deposit together onto the cathode mother body and stripping the composite electroformed layer, integrated nanometer alumina particle reinforced copper base composite material is produced. The produced composite material has high strength, high ductibility and relatively great thickness, and may be used as functional structure material.

Lei Liu

Papers

Antifriction and Wear Characteristics of Electrolessly-Deposited Ni–P with PTFE Composites

Effects of Elastic and Plastic Deformations on Corrosion of an Aluminum Bronze Alloy in NaCl Solution

Surface-modified micrometre nickel hollow spheres and their microwave characteristics

Preparation of submicron-sized cuprous oxide crystallites by electrodeposition with polyethylene glycol as additive

Composite electroforming preparing process for nano aluminium oxide particle reinforced copper base composite material