Self-supported Zn3P2 nanowire arrays grafted on carbon fabrics as an advanced integrated anode for flexible lithium ion batteries

Electrochemical Characteristics of Amorphous Ni-P Electroplated Thin Film

In this study, an amorphous nickel-phosphide (Ni-P) thin film was produced by electroplating, and its possible use as the anode material of a secondary lithium battery was explored. First, by changing the electroplating conditions, we created uniform and flat Ni-P thin films that contained 16–28 at% phosphorus. An evaluation of the manufactured thin film as anode material showed that a thin film with more phosphorus content had a higher specific discharge capacity. In particular, the initial gravimetric capacity of the electrode with the highest phosphorus content (28 at%) was comparable to that of graphite, but it had three times the initial volumetric capacity. The cycling stability improved with a higher phosphorus content. It was suggested that the adhesive strength between the substrate and thin film had a greater impact on the cycling stability than the physical damage caused by the volume changes during charging and discharging. To improve the specific capacity, we formed globular electrodeposits on the surface of the thin film. As a result, a discharge capacity comparable to the theoretical capacity of Ni-P was obtained, and the rate performance was additionally improved, without reduction in the life cycle.

A Flexible and Transparent Zinc-Nanofiber Network Electrode for Wearable Electrochromic, Rechargeable Zn-Ion Battery

The flexible electrochromic Zn-ion battery (FE-ZiB), a newly born energy-storage technology having both electrochromic characteristics and energy-storage capability in a single device, will be a promising technology for the future transparent wearable electronics. However, the current technology limits the fabrication of FE-ZIB because the zinc (Zn) anode material is opaque and rigid. The development of a flexible and transparent Zn anode is the key factor to overcoming the current limitation. Here, for the first time, a flexible, transparent zinc-nanofiber network anode electrode (Zn@Ni@AgNFs) is reported for an FE-ZiB device that yields a remarkable electrochemical performance of a high areal capacity of 174.82 mA h m² at 0.013 mA cm^-2 applied current density, high optical contrast (50%), and excellent mechanical flexibility. The fabricated FE-ZiB device also exhibits a high volumetric energy density of 378.8 W h m^-3 at a power density of 562.7 W m^-3 . Besides, the FE-ZiB demonstrates excellent electrochromic capability with a reversible color transition from a transparent in a discharged state (0.3 V) to a dark bluish-violet in a charged state (1.6 V). These results highlight a new pathway for the development of transparent batteries for smart wearable electronic devices.

One-Dimensional (1D) Nanostructured Materials for Energy Applications

At present, the world is at the peak of production of traditional fossil fuels. Much of the resources that humanity has been consuming (oil, coal, and natural gas) are coming to an end. The human being faces a future that must necessarily go through a paradigm shift, which includes a progressive movement towards increasingly less polluting and energetically viable resources. In this sense, nanotechnology has a transcendental role in this change. For decades, new materials capable of being used in energy processes have been synthesized, which undoubtedly will be the cornerstone of the future development of the planet. In this review, we report on the current progress in the synthesis and use of one-dimensional (1D) nanostructured materials (specifically nanowires, nanofibers, nanotubes, and nanorods), with compositions based on oxides, nitrides, or metals, for applications related to energy. Due to its extraordinary surface-volume relationship, tunable thermal and transport properties, and its high surface area, these 1D nanostructures have become fundamental elements for the development of energy processes. The most relevant 1D nanomaterials, their different synthesis procedures, and useful methods for assembling 1D nanostructures in functional devices will be presented. Applications in relevant topics such as optoelectronic and photochemical devices, hydrogen production, or energy storage, among others, will be discussed. The present review concludes with a forecast on the directions towards which future research could be directed on this class of nanostructured materials.

Review on carbonaceous materials and metal composites in deformable electrodes for flexible lithium-ion batteries

With the rapid propagation of flexible electronic devices, flexible lithium-ion batteries (FLIBs) are emerging as the most promising energy supplier among all of the energy storage devices owing to their high energy and power densities with good cycling stability. As a key component of FLIBs, to date, researchers have tried to develop newly designed high-performance electrochemically and mechanically stable pliable electrodes. To synthesize better quality flexible electrodes, based on high conductivity and mechanical strength of carbonaceous materials and metals, several research studies have been conducted. Despite both materials-based electrodes demonstrating excellent electrochemical and mechanical performances in the laboratory experimental process, they cannot meet the expected demands of stable flexible electrodes with high energy density. After all, various significant issues associated with them need to be overcome, for instance, poor electrochemical performance, the rapid decay of the electrode architecture during deformation, and complicated as well as costly production processes thus limiting their expansive applications. Herein, the recent progression in the exploration of carbonaceous materials and metals based flexible electrode materials are summarized and discussed, with special focus on determining their relative electrochemical performance and structural stability based on recent advancement. Major factors for the future advancement of FLIBs in this field are also discussed.

Flexible 3D carbon cloth as a high-performing electrode for energy storage and conversion

High-performance energy storage and conversion devices with high energy density, power density and long-term cycling life are of great importance in current consumer electronics, portable electronics and electric vehicles. Carbon materials have been widely investigated and utilized in various energy storage and conversion devices due to their excellent conductivity, mechanical and chemical stability, and low cost. Abundant excellent reviews have summarized the most recent progress and future outlooks for most of the current prime carbon materials used in energy storage and conversion devices, such as carbon nanotubes, fullerene, graphene, porous carbon and carbon fibers. However, the significance of three-dimensional (3D) commercial carbon cloth (CC), one of the key carbon materials with outstanding mechanical stability, high conductivity and flexibility, in the energy storage and conversion field, especially in wearable electronics and flexible devices, has not been systematically summarized yet. In this review article, we present a careful investigation of flexible CC in the energy storage and conversion field. We first give a general introduction to the common properties of CC and the roles it has played in energy storage and conversion systems. Then, we meticulously investigate the crucial role of CC in typical electrochemical energy storage systems, including lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries and supercapacitors. Following a description of the wide application potential of CC in electrocatalytic hydrogen evolution, oxygen evolution/reduction, full-water splitting, etc., we will give a brief introduction to the application of CC in the areas of photocatalytically and photoelectrochemically induced solar energy conversion and storage. The review will end with a brief summary of the typical superiorities that CC has in current energy conversion and storage systems, as well as providing some perspectives and outlooks on its future applications in the field. Our main interest will be focused on CC-based flexible devices due to the inherent superiority of CC and the increasing demand for flexible and wearable electronics.

Vapor Phase Growth of Semiconductor Nanowires: Key Developments and Open Questions

Nanowires are filamentary crystals with a tailored diameter that can be obtained using a plethora of different synthesis techniques. In this review, we focus on the vapor phase, highlighting the most influential achievements along with a historical perspective. Starting with the discovery of VLS, we feature the variety of structures and materials that can be synthesized in the nanowire form. We then move on to establish distinct features such as the three-dimensional heterostructure/doping design and polytypism. We summarize the status quo of the growth mechanisms, recently confirmed by in situ electron microscopy experiments and defining common ground between the different synthesis techniques. We then propose a selection of remaining defects, starting from what we know and going toward what is still to be learned. We believe this review will serve as a reference for neophytes but also as an insight for experts in an effort to bring open questions under a new light.

A multidimensional and hierarchical carbon-confined cobalt phosphide nanocomposite as an advanced anode for lithium and sodium storage

Transition metal phosphides possess remarkable theoretical charge capacities; however, they demonstrate poor intrinsic electrical conductivity and enormous structure changes during cycling. Herein, a novel, multidimensional and hierarchical nanostructure is synthesized which constitutes 0D CoP nanoparticles distrbuted in a 1D dual carbon matrix and further homogenously encapsulated in a 3D graphene (GR) network; this material is denoted as CoP@DC@GR. This synergistic design produces superior advantages for lithium and sodium storage: (i) the ultrasmall and highly dispersed 0D CoP nanoparticles embedded in the 1D dual carbon matrix can decrease the electron/ion transport paths; (ii) the 3D interconnected architecture constructed from 2D GR and the 1D dual carbon matrix guarantees a robust structure to withstand the mechanical stress of the 1D dual carbon matrix, which can relieve volume inflation of the 0D CoP nanoparticles; (iii) the 1D dual carbon matrix and 3D GR frame structure offer continuous electron/ion transport routes, thus promoting rapid reaction kinetics. Due to this multiscale coordinated design, the CoP@DC@GR nanocomposite demonstrates high charge capacity, remarkable cycle stability, and distinguished rate performance; therefore, it possesses fascinating potential in anodes for lithium and sodium storage.

High Areal Capacity Li-Ion Storage of Binder-Free Metal Vanadate/Carbon Hybrid Anode by Ion-Exchange Reaction

Storing more energy in a limited device area is very challenging but crucial for the applications of flexible and wearable electronics. Metal vanadates have been regarded as a fascinating group of materials in many areas, especially in lithium-ion storage. However, there has not been a versatile strategy to synthesize flexible metal vanadate hybrid nanostructures as binder-free anodes for Li-ion batteries so far. A convenient and versatile synthesis of M_x V_y O_x+2.5y @carbon cloth (M = Mn, Co, Ni, Cu) composites is proposed here based on a two-step hydrothermal route. As-synthesized products demonstrate hierarchical proliferous structure, ranging from nanoparticles (0D), and nanobelts (1D) to a 3D interconnected network. The metal vanadate/carbon hybrid nanostructures exhibit excellent lithium storage capability, with a high areal specific capacity up to 5.9 mAh cm^-2 (which equals to 1676.8 mAh g^-1 ) at a current density of 200 mA g^-1 . Moreover, the nature of good flexibility, mixed valence states, and ultrahigh mass loading density (over 3.5 mg cm^-2 ) all guarantee their great potential in compact energy storage for future wearable devices and other related applications.

Phosphinecarboxamide as an unexpected phosphorus precursor in the chemical vapour deposition of zinc phosphide thin films

This paper demonstrates the use of phosphinecarboxamide as a facile phosphorus precursor, which can be used alongside zinc acetate for the chemical vapour deposition (CVD) of adherent and crystalline zinc phosphide films. Thin films of Zn3P2 have a number of potential applications and phosphinecarboxamide is a safer and more efficient precursor than the highly toxic, corrosive and flammable phosphine used in previous CVD syntheses.

Coralloidal carbon-encapsulated CoP nanoparticles generated on biomass carbon as a high-rate and stable electrode material for lithium-ion batteries

Architecture of electrode materials plays an important role in achieving favorable electrochemical performance via providing fast electronic transport pathway and shorten lithium ion diffusion distance. Herein, ultrafine CoP nanoparticles were successfully embedded in carbon nanorod, which were grown on the biomass-derived carbon (BC). When applied as anode materials for lithium-ion batteries, these CoP@C/BC displayed capable specific capacity, remarkable rate ability and outstanding long-term cycling performance. The capacity was governed by combination of diffusion-controlled and capacitive processes, according to quantitative kinetic analysis. The good electrochemical performance is attributed to hierarchical construction of nanosized CoP embedded in carbon nanorod and BC with high conductivity composite, which relieve the volume changing of CoP and provide large electrode/electrolyte interface. The present design of hierarchical architecture can be extended to other transition metal-based oxides, sulfide and phosphide electrode materials for high performance alkali metal ion batteries.

FeP@C Nanotube Arrays Grown on Carbon Fabric as a Low Potential and Freestanding Anode for High-Performance Li-Ion Batteries

An anode of self-supported FeP@C nanotube arrays on carbon fabric (CF) is successfully fabricated via a facile template-based deposition and phosphorization route: first, well-aligned FeOOH nanotube arrays are simply obtained via a solution deposition and in situ etching route with hydrothermally crystallized (Co,Ni)(CO₃ )_0.5 OH nanowire arrays as the template; subsequently, these uniform FeOOH nanotube arrays are transformed into robust carbon-coated Fe₃ O₄ (Fe₃ O₄ @C) nanotube arrays via glucose adsorption and annealing treatments; and finally FeP@C nanotube arrays on CF are achieved through the facile phosphorization of the oxide-based arrays. As an anode for lithium-ion batteries (LIBs), these FeP@C nanotube arrays exhibit superior rate capability (reversible capacities of 945, 871, 815, 762, 717, and 657 mA h g^-1 at 0.1, 0.2, 0.4, 0.8, 1.3, and 2.2 A g^-1 , respectively, corresponding to area specific capacities of 1.73, 1.59, 1.49, 1.39, 1.31, 1.20 mA h cm^-2 at 0.18, 0.37, 0.732, 1.46, 2.38, and 4.03 mA cm^-2 , respectively) and a stable long-cycling performance (a high specific capacity of 718 mA h g^-1 after 670 cycles at 0.5 A g^-1 , corresponding to an area capacity of 1.31 mA h cm^-2 at 0.92 mA cm^-2 ).

Facile Synthesis of Layer Structured GeP3/C with Stable Chemical Bonding for Enhanced Lithium-Ion Storage

Recently, metal phosphides have been investigated as potential anode materials because of higher specific capacity compared with those of carbonaceous materials. However, the rapid capacity fade upon cycling leads to poor durability and short cycle life, which cannot meet the need of lithium-ion batteries with high energy density. Herein, we report a layer-structured GeP₃/C nanocomposite anode material with high performance prepared by a facial and large-scale ball milling method via in-situ mechanical reaction. The P-O-C bonds are formed in the composite, leading to close contact between GeP₃ and carbon. As a result, the GeP₃/C anode displays excellent lithium storage performance with a high reversible capacity up to 1109 mA h g⁻¹ after 130 cycles at a current density of 0.1 A g⁻¹. Even at high current densities of 2 and 5 A g⁻¹, the reversible capacities are still as high as 590 and 425 mA h g⁻¹, respectively. This suggests that the GeP₃/C composite is promising to achieve high-energy lithium-ion batteries and the mechanical milling is an efficient method to fabricate such composite electrode materials especially for large-scale application.

NiCo₂O₄-Based Supercapacitor Nanomaterials

In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo₂O₄ fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness. Finally, the review will be concluded with the perspectives on the future development of spinel NiCo₂O₄ utilized as the supercapacitor electrodes.

New insights and perspectives into biological materials for flexible electronics

Materials based on biological materials are becoming increasingly competitive and are likely to be critical components in flexible electronic devices.