Nanostructured electrodes for lithium-ion and lithium-air batteries: the latest developments, challenges, and perspectives

The urgency for clean and secure energy has stimulated a global resurgence in searching for advanced electrical energy storage systems. For now and the foreseeable future, batteries remain the most promising electrical energy storage systems for many applications, from portable electronics to emerging technologies such as electric vehicles and smart grids, by potentially offering significantly improved performance, energy efficiencies, reliability, and energy security while also permitting a drastic reduction in fuel consumption and emissions. The energy and power storage characteristics of batteries critically impact the commercial viability of these emerging technologies. For example, the realization of electric vehicles hinges on the availability of batteries with significantly improved energy and power density, durability, and reduced cost. Further, the design, performance, portability, and innovation of many portable electronics are limited severely by the size, power, and cycle life of the existing batteries. Creation of nanostructured electrode materials represents one of the most attractive strategies to dramatically enhance battery performance, including capacity, rate capability, cycling life, and safety. This review aims at providing the reader with an understanding of the critical scientific challenges facing the development of advanced batteries, various unique attributes of nanostructures or nano-architectures applicable to lithium-ion and lithium-air batteries, the latest developments in novel synthesis and fabrication procedures, the unique capabilities of some powerful, in situ characterization techniques vital to unraveling the mechanisms of charge and mass transport processes associated with battery performance, and the outlook for future-generation batteries that exploit nanoscale materials for significantly improved performance to meet the ever-increasing demands of emerging technologies.     

Selenium nanomaterials: An overview of recent developments in synthesis,properties and potential applications

Advances in science and nanotechnology have facilitated the development of new methods for the preparation of pure selenium as selenium nanomaterials. They offer remarkable potential for technological applications in the fields of medicine, diagnostics, therapeutics, toxicology, electronics, catalysis and so on. Moreover, selenium nanomaterials also find applications in photographic exposure metres, rectifiers, signal emitting devices and transmitting devices, because of their unique structural, optical and electronic properties. This study describes a detailed advanced report on the synthesis, assembly, characterization and various applications of selenium nanomaterials. In addition, relevant synthesis methods, properties, challenges and opportunities associated with selenium nanomaterials are also presented.     

Structural batteries: Advances,challenges and perspectives

The development of light-weight batteries has a great potential value for mobile applications, including electric vehicles and electric aircraft. Along with increasing energy density, another strategy for reducing battery weight is to endow energy storage devices with multifunctionality – e.g., creating an energy storage device that is able to bear structural loads and act as a replacement for structural components such that the weight of the overall system is reduced. This type of batteries is commonly referred to as “structural batteries”. Two general methods have been explored to develop structural batteries: (1) integrating batteries with light and strong external reinforcements, and (2) introducing multifunctional materials as battery components to make energy storage devices themselves structurally robust. In this review, we discuss the fundamental rules of design and basic requirements of structural batteries, summarize the progress made to date in this field, examine potential avenues and sources of inspiration for future research, and touch upon challenges remaining in this field such as safety, costs, and performance stability. Though more fundamental and technical research is needed to promote wide practical application, structural batteries show the potential to significantly improve the performance of electric vehicles and devices.     

A review of the recent developments in biocomposites based on natural fibres and their application perspectives

The growing ecological and environmental consciousness has driven efforts for development of new innovative materials for various end-use applications. Polymers synthesized from natural resources, have gained considerable research interest in the recent years. This review paper is intended to provide a brief outline of work that covers in the area of biocomposites, major class of biodegradable polymers, natural fibres, as well as their manufacturing techniques and properties has been highlighted. Various surface modification methods were incorporated to improve the fibre–matrix adhesion resulting in the enhancement of mechanical properties of the biocomposites. Moreover, an economical impact and future direction of these materials has been critically reviewed. This review concludes that the biocomposites form one of the emerging areas in polymer science that gain attention for use in various applications ranging from automobile to the building industries.     

Tribology of SiC ceramics under lubrication: Features,developments, and perspectives

Silicon carbide ceramics have many outstanding properties like high hardness, high thermal conductivity, high strength, low density, good electrical conductivity, good chemical resistance, and excellent wear resistance. Because of their valuable properties, SiC ceramics are helpful in various tribological applications. In this paper, the features and developments of tribology of SiC ceramics under lubrication are reviewed. The relevant strategies to enhance the tribological performance of SiC ceramics under lubrication, including microstructures, mechanical properties, surface characteristics, external factors, and secondary phases, are comprehensively discussed. The tribochemical reactions and Stribeck curves of SiC ceramics are also presented. Finally, future research directions of SiC ceramics in the field of tribology under lubrication are proposed. This paper aims to offer some theoretical basis for the design of low-friction and low-wear SiC ceramics under lubrication in the future and a better understanding of SiC ceramics used as various tribological components under lubrication.     

Electron paramagnetic resonance: recent developments and trends

Major recent advances:High-field multi-frequency EPR improves our knowledge of magnetic materials, conductive polymers, and spin systems with large zero-field splittings. High-field electron nuclear double resonance provides better access to subtle details of the electronic structure of materials. Materials structure on length scales between 1.5 and 8 nm can now be characterized more precisely.     

Heavy fermions: Typical phenomena and recent developments

A survey is given of typical phenomena, new materials and recent developments in heavy-fermion physics. In particular, the following topics are addressed: (i) YbNiAl, a new heavy-fermion local-moment antiferromagnet (LMM) with Néel temperature T_n = 3 K, (ii) non-Fermi-liquid behavior at the magnetic instability in two heavy-fermion systems with intact f-ion sublattice, i.e. orthorhombic CePt(Si_1–xGe_x) and tetragonal U(Cu_4+xAl_8–x), (iii) the low-temperature properties of the anisotropic Rondo insulator CeNiSn, and (iv) some of the most unusual observations made on low-carrier-density rare-earth systems like Sm₃Te₄ and Sm₃Se₄. While the exotic symmetry-broken (superconducting and magnetic) ground states of heavy-fermion metals are discussed in several other contributions to this volume, we focus in the remainder of this paper on the relationship between LMM ordering and heavy-fermion superconductivity: Firstly, the LMM ordered compound CeCu₂Ge₂ (T_n = 4.1K) is addressed which was recently found to become a non-magnetic heavy-fermion superconductor under high hydrostatic pressure, p 70 kbar (D. Jaccard et al., Phys. Lett. A163,475 (1992)). Point-contact spectroscopy is used to investigate in more detail the high-pressure superconducting phase of CeCu₂Ge₂. Secondly, we summarize high-pressure results on UPd₂Al₃, the first compound to show homogeneous coexistence between LMM ordering and heavy-fermion superconductivity.     

Introduction: recent developments in the study of gamma-ray bursts

Gamma-ray bursts (GRBs) are immensely powerful explosions, originating at cosmological distances, whose outbursts persist for durations ranging from milliseconds to tens of seconds or more. In these brief moments, the explosions radiate more energy than the Sun will release in its entire 10Gyr lifetime. Current theories attribute these phenomena to the final collapse of a massive star, or the coalescence of a binary system induced by gravity wave emission. New results from Swift and related programmes offer fresh understanding of the physics of GRBs, and of the local environments and host galaxies of burst progenitors. Bursts found at very high red shifts are new tools for exploring the intergalactic medium, the first stars and the earliest stages of galaxy formation. This Royal Society Discussion Meeting has brought together leading figures in the field, together with young researchers and students, to discuss and review the latest results from NASA's Swift Gamma-ray Burst Observatory and elsewhere, and to examine their impact on current understanding of the observed phenomena.     

Reverse engineering and identification in systems biology: strategies,perspectives and challenges

The interplay of mathematical modelling with experiments is one of the central elements in systems biology. The aim of reverse engineering is to infer, analyse and understand, through this interplay, the functional and regulatory mechanisms of biological systems. Reverse engineering is not exclusive of systems biology and has been studied in different areas, such as inverse problem theory, machine learning, nonlinear physics, (bio)chemical kinetics, control theory and optimization, among others. However, it seems that many of these areas have been relatively closed to outsiders. In this contribution, we aim to compare and highlight the different perspectives and contributions from these fields, with emphasis on two key questions: (i) why are reverse engineering problems so hard to solve, and (ii) what methods are available for the particular problems arising from systems biology?     

Theory of defects in Si and Ge: Past, present and recent developments

Over the past few decades, considerable progress has been achieved in the theoretical predictions of a wide range of properties of defects in semiconductors. In addition to structures, energetics, spin and charge densities, theory now routinely predicts accurate vibrational properties of defects, and thus connects to the optical characterization of light impurities. However, the positions of gap levels have yet to be predicted with systemically reliable accuracy. Today, supercells much larger than in the past are being used to describe defect centers from first principles. Systems large enough to study the dynamics of extended defects can be handled near the first-principles level. This paper contains a brief review of the key developments that have rendered theory quantitatively useful to experimentalists and an overview of the current ‘state-of-the-art’ and ongoing developments. Some of the remaining challenges are discussed, with examples in Si and Ge.     

Carbon nanotube based transparent conductive films: progress,challenges, and perspectives

Developments in the manufacturing technology of low-cost, high-quality carbon nanotubes (CNTs) are leading to increased industrial applications for this remarkable material. One of the most promising applications, CNT based transparent conductive films (TCFs), are an alternative technology in future electronics to replace traditional TCFs, which use indium tin oxide. Despite significant price competition among various TCFs, CNT-based TCFs have good potential for use in emerging flexible, stretchable and wearable optoelectronics. In this review, we summarize the recent progress in the fabrication, properties, stability and applications of CNT-based TCFs. The challenges of current CNT-based TCFs for industrial use, in comparison with other TCFs, are considered. We also discuss the potential of CNT-based TCFs, and give some possible strategies to reduce the production cost and improve their conductivity and transparency.     

Review on photocatalytic and electrocatalytic artificial nitrogen fixation for ammonia synthesis at mild conditions: Advances,challenges and perspectives

The ammonia synthesis from nitrogen and water under ambient conditions is one of the most inviting but challenging reaction routes. Although nitrogen is abundant in the atmosphere and the ammonia synthesis reaction is exothermic on the thermodynamics, the conversion of N₂ to ammonia is actually hard to proceed owing to the chemical inertness and stability of N₂ molecules. In industry, ammonia synthesis is carried out by the Haber-Bosch process under harsh conditions (300–500 °C, 20–30 MPa) associated with the requirement of substantial energy input and the enormous emission of greenhouse gases (e.g., CO₂). Recently, a growing number of studies on photo(electro)catalytic and electrocatalytic nitrogen reduction reaction (NRR) in aqueous solution have attracted extensive attention, which holds great promise for nitrogen fixation under room temperature and atmospheric pressure. However, the very low efficiency and ambiguous mechanism still remain as the major hurdles for the development of photochemical and electrochemical NRR systems. Here we provide an overview of the latest progresses, remaining challenges and future prospects in photocatalytic and electrocatalytic nitrogen fixation. Moreover, this review offers a helpful guidance for the reasonable design of photocatalysts and electrocatalysts towards NRR by combining theory predictions and experiment results. We hope this review can stimulate more research interests in the relatively understudied but highly promising research field of NRR.

     

Alloy design via additive manufacturing: Advantages,challenges, applications and perspectives

Additive manufacturing (AM) has rapidly changed both large- and small-scale production environments across many industries. By re-envisioning parts from the ground up, not limited to the challenges presented by traditional manufacturing techniques, researchers and engineers have developed new design strategies to solve large-scale materials and design problems worldwide. This is particularly true in the world of alloy design, where new metallic materials have historically been developed through tedious processes and procedures based primarily on casting methodologies. With the onset of directed energy deposition (DED) and powder bed fusion (PBF)-based AM, new alloys can be innovated and evaluated rapidly at a lower cost and considerably shorter lead time than has ever been achieved. This article details the advantages, challenges, applications, and perspectives of alloy design using primarily laser-based AM. It is envisioned that researchers in industry and academia can utilize this work to design new alloys leveraging metallic AM processes for various current and future applications.     

Magnetic nanoparticles: recent developments in drug delivery system

Nanostructured functional materials have demonstrated their great potentials in medical applications, attracting increasing attention because of the opportunities in cancer therapy and the treatment of other ailments. This article reviews the problems and recent advances in the development of magnetic NPs for drug delivery.     

Recent developments in inorganically filled carbon nanotubes: successes and challenges

Abstract

Carbon nanotubes (CNTs) are a unique class of nanomaterials that can be imagined as rolled graphene sheets. The inner hollow of a CNT provides an extremely small, one-dimensional space for storage of materials. In the last decade, enormous effort has been spent to produce filled CNTs that combine the properties of both the host CNT and the guest filling material. CNTs filled with various inorganic materials such as metals, alloys, semiconductors and insulators have been obtained using different synthesis approaches including capillary filling and chemical vapor deposition. Recently, several potential applications have emerged for these materials, such as the measurement of temperature at the nanoscale, nano-spot welding, and the storage and delivery of extremely small quantities of materials. A clear distinction between this class of materials and other nanostructures is the existence of an enormous interfacial area between the CNT and the filling matter. Theoretical investigations have shown that the lattice mismatch and strong exchange interaction of CNTs with the guest material across the interface should result in reordering of the guest crystal structure and passivation of the surface dangling bonds and thus yielding new and interesting physical properties. Despite preliminary successes, there remain many challenges in realizing applications of CNTs filled with inorganic materials, such as a comprehensive understanding of their growth and physical properties and control of their structural parameters. In this article, we overview research on filled CNT nanomaterials with special emphasis on recent progress and key achievements. We also discuss the future scope and the key challenges emerging out of a decade of intensive research on these fascinating materials.