Mrs Bulletin最新文献

Abstract

Addressing the growing demand for conductive and flexible composites, this research focuses on producing thermoplastic composite fibers made of polyurethane and carbon nanomaterials featuring the highest possible electrical conductivity. Based on a recently developed methodology enabling the formation of very high filler contents of 40% w/w, this work presents a systematic investigation of the role of all the materials used during the manufacturing process and selects the materials that ensure the best electrical performance. The results show that the highest electrical conductivity and current-carrying capacities are obtained when dimethylformamide is used as a solvent, and small amounts of AKM surfactant aid the de-agglomeration of carbon nanomaterials. It is also shown that the hybridization of MWCNTs filler with graphene nanoplatelets and small amounts of carbon black is beneficial for the electrical properties. However, the highest performance is achieved with SWCNTs as fillers, exhibiting two orders of magnitude higher electrical conductivities of 6.17 × 10⁴ S/m.

Impact statement

The article presents a pioneering exploration into the synthesis and application of a novel composite material. This research significantly impacts the field of electromaterials by introducing a cutting-edge approach that leverages the synergistic properties of carbon nanotubes, graphene, and carbon black within a single filament. The impact of this research extends beyond the laboratory, influencing the development of next-generation materials that bridge the gap between conventional materials and advanced nanomaterials. The presented composite filaments open avenues for the creation of innovative devices and systems that demand good mechanical strength, electrical conductivity, and thermal stability. Moreover, the versatility of these filaments allows for the optimization of materials properties, enabling customization based on specific application requirements. In addition to its technological significance, the paper contributes to sustainability efforts by facilitating the production of lightweight, energy-efficient materials. The insights provided by this research have the potential to reshape the landscape of materials science, inspiring further exploration and innovation in the quest for versatile and high-performance electromaterials.

Graphical abstract

Global demand for batteries is increasing at a rapid pace, precipitating the equally rapid generation of hazardous battery waste. Recycling, which holds high potential for both mitigating this waste and recovering raw materials for subsequent battery manufacture, is often recognized as a necessary component of the battery life cycle. A critical step in many battery recycling schemes is the use of solvent to recover valuable metals such as lithium, cobalt, manganese, nickel, and others. This recovery typically involves the use of harsh mineral acids and peroxides, which pose their own environmental and safety hazards. The use of more benign organic acids and other organic compounds has emerged as a promising means to mitigate the hazards posed by purely inorganic solvents. In this article, we review recent research on organics-based metal recovery for battery recycling and provide our perspective on the extant challenges and opportunities in the field.

Graphical abstract

Increasing demand for electric vehicles (EVs) is increasing demand for the permanent magnets that drive their motors, as approximately 80% of modern EV drivetrains rely on high-performance permanent magnets to convert electricity into torque. In turn, these high-performance permanent magnets rely on rare earth elements for their magnetic properties. These elements are “critical” (i.e., at risk of limiting the growth of renewable energy technologies such as EVs), which motivates an exploration for alternative materials. In this article, we overview the relevant fundamentals of permanent magnets, describe commercialized and emerging materials, and add perspective on future areas of research. Currently, the leading magnetic material for EV motors is Nd₂Fe₁₄B, with samarium-cobalt compounds (SmCo₅ and Sm₂Co₁₇) providing the only high-performing commercialized alternative. Emerging materials that address criticality concerns include Sm₂Fe₁₇N₃, Fe₁₆N₂, and the L1₀ structure of FeNi, which use lower cost elements that produce similar magnetic properties. However, these temperature-sensitive materials are incompatible with current metallurgical processing techniques. We provide perspective on how advances in low-temperature synthesis and processing science could unlock new classes of high-performing magnetic materials for a paradigm shift beyond rare earth-based magnets. In doing so, we explore the question: What magnetic materials will drive future EVs?

Graphical abstract

Abstract

An oblique helicoidal state of a cholesteric liquid crystal (Ch_OH) is capable of continuous change of the pitch (P) in response to an applied electric field. Such a structure reflects 50% of the unpolarized light incident along the Ch_OH axis in the electrically tunable band determined by (P)/2. Here, we demonstrate that at an oblique incidence of light, Ch_OH reflects 100% of light of any polarization. This singlet band of total reflection is associated with the full pitch (P). We also describe the satellite (P/2), (P/3), and (P/4) bands. The (P/2) and (P/4) bands are triplets, whereas (P/3) band is a singlet caused by multiple scatterings at (P) and (P/2). A single Ch_OH cell acted upon by an electric field tunes all these bands in a very broad spectral range, from ultraviolet to infrared and beyond, thus representing a structural color device with enormous potential for optical and photonic applications.

Impact statement

Pigments, inks, and dyes produce colors by partially consuming the energy of light. In contrast, structural colors caused by interference and diffraction of light scattered at submicrometer length scales do not involve energy losses, which explains their widespread in Nature and the interest of researchers to develop mimicking materials. The grand challenge is to produce materials in which the structural colors could be dynamically tuned. Among the oldest known materials producing structural colors are cholesteric liquid crystals. Light causes coloration by selective Bragg reflection at the periodic helicoidal structure formed by cholesteric molecules. The cholesteric pitch and thus the color can be altered by chemical composition or by temperature, but, unfortunately, dynamic tuning by electromagnetic field has been elusive. Here, we demonstrate that a cholesteric material in a new oblique helicoidal Ch_OH state could produce total reflection of an obliquely incident light of any polarization. The material reflects 100% of light within a band that is continuously tunable by the electric field through the entire visible spectrum while preserving its maximum efficiency. Broad electric tunability of total reflection makes the Ch_OH material suitable for applications in energy-saving smart windows, transparent displays, communications, lasers, multispectral imaging, and virtual and augmented reality.

Graphical Abstract