Aluminum Alloy Anode with Various Iron Content Influencing the Performance of Aluminum-Ion Batteries.

Considerable research has been devoted to the development of cathode materials for Al-ion batteries, but challenges remain regarding the behavior of aluminum anodes. Inert oxide (AlO) film on Al surfaces presents a barrier to electrochemical activity. The structure of the oxide film needs to be weakened to facilitate ion transfer during electrochemical activity.

Advances in Inorganic Nanomaterials for Triboelectric Nanogenerators.

Triboelectric nanogenerators (TENGs) that utilize triboelectrification and electrostatic induction to convert mechanical energy to electricity have attracted increasing interest in the last 10 years. As a universal physical phenomenon, triboelectrification can occur between any two surfaces that experience physical contact and separation regardless of the type of material. For this reason, many materials, including both organic and inorganic materials, have been studied in TENGs with different purposes.

A review of the advances in composites/nanocomposites for triboelectric nanogenerators.

Material development is essential when studying triboelectric nanogenerators (TENGs). This importance is because the performance of TENGs is highly dependent on the properties of the utilized triboelectric materials. To obtain more specific properties, composites have been developed that combine the features of their components.

Treatment of NiMoO4/nanographite nanocomposite electrodes using flexible graphite substrate for aqueous hybrid supercapacitors.

The cycling performance of supercapacitors sometimes becomes limited when electrode materials slough off during frequent charge-discharge cycles, due to weak bonding between the active material and the current collector. In this work, a flexible graphite foil substrate was successfully used as the current collector for supercapacitor electrodes. Graphite foil substrates were treated in different ways with different acid concentrations and temperatures before being coated with an active material (NiMoO4/nanographite).

Highly Stable Cycling of Silicon-Nanographite Aerogel-Based Anode for Lithium-Ion Batteries.

Silicon anodes are considered as promising electrode materials for next-generation high capacity lithium-ion batteries (LIBs). However, the capacity fading due to the large volume changes (∼300%) of silicon particles during the charge-discharge cycles is still a bottleneck. The volume changes of silicon lead to a fracture of the silicon particles, resulting in recurrent formation of a solid electrolyte interface (SEI) layer, leading to poor capacity retention and short cycle life.

Cellulose-Based Fully Green Triboelectric Nanogenerators with Output Power Density of 300 W m.

Triboelectric nanogenerators (TENGs) have attracted increasing attention because of their excellent energy conversion efficiency, the diverse choice of materials, and their broad applications in energy harvesting devices and self-powered sensors. New materials have been explored, including green materials, but their performances have not yet reached the level of that for fluoropolymers. Here, a high-performance, fully green TENG (FG-TENG) using cellulose-based tribolayers is reported.

Structure, Performance, and Application of BiFeO Nanomaterials.

Multiferroic nanomaterials have attracted great interest due to simultaneous two or more properties such as ferroelectricity, ferromagnetism, and ferroelasticity, which can promise a broad application in multifunctional, low-power consumption, environmentally friendly devices. Bismuth ferrite (BiFeO, BFO) exhibits both (anti)ferromagnetic and ferroelectric properties at room temperature. Thus, it has played an increasingly important role in multiferroic system.

Influence of Substrate in Roll-to-roll Coated Nanographite Electrodes for Metal-free Supercapacitors.

Due to the high electric conductivity and large surface area of nanographites, such as graphene and graphite nanoplatlets, these materials have gained a large interest for use in energy storage devices. However, due to the thin flake geometry, the viscosity of aqueous suspensions containing these materials is high even at low solids contents. This together with the use of high viscosity bio-based binders makes it challenging to coat in a roll-to-roll process with sufficient coating thickness.

Laser-Etched Stretchable Graphene-Polymer Composite Array for Sensitive Strain and Viscosity Sensors.

The ability to control surface wettability and liquid spreading on textured surfaces is of interest for extensive applications. Soft materials have prominent advantages for producing the smart coatings with multiple functions for strain sensing. Here, we report a simple method to prepare flexible hydrophobic smart coatings using graphene-polymer films.

Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries.

To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films.

Gold and ZnO-Based Metal-Semiconductor Network for Highly Sensitive Room-Temperature Gas Sensing.

Metal-semiconductor junctions and interfaces have been studied for many years due to their importance in applications such as semiconductor electronics and solar cells. However, semiconductor-metal networks are less studied because there is a lack of effective methods to fabricate such structures. Here, we report a novel Au-ZnO-based metal-semiconductor (M-S) network in which ZnO nanowires were grown horizontally on gold particles and extended to reach the neighboring particles, forming an (M-S) network.

Effects of geometry on large-scale tube-shear exfoliation of graphite to multilayer graphene and nanographite in water.

Industrially scalable methods for the production of graphene and other nanographites are needed to achieve cost-efficient commercial products. At present, there are several available routes for the production of these materials but few allow large-scale manufacturing and environmentally friendly low-cost solvents are rarely used. We have previously demonstrated a scalable and low-cost industrial route to produce nanographites by tube-shearing in water suspensions.

Frequency and voltage response of a wind-driven fluttering triboelectric nanogenerator.

Triboelectric nanogenerators (TENG:s) are used as efficient energy transducers in energy harvesting converting mechanical energy into electrical energy. Wind is an abundant source of mechanical energy but how should a good triboelectric wind harvester be designed? We have built and studied a TENG driven by air flow in a table-top sized wind tunnel. Our TENG constitutes of a plastic film of size 10 cm × 2 cm which is fluttering between two copper electrodes generating enough power to light up a battery of LED:s.

Selective laser sintering of inkjet-printed silver nanoparticle inks on paper substrates to achieve highly conductive patterns.

Development of cost-effective and environmentally friendly manufacturing methods will enable important advances for the production of large-scale flexible electronics. Laser processing has shown to be a promising candidate that offers a fast and non-destructive way to produce highly conductive patterns on flexible substrates such as plastics. However, an emerging option with a lower environmental impact is instead the use of cellulose-based flexible substrates, such as paper.

Escherichia coli Bacteria Develop Adaptive Resistance to Antibacterial ZnO Nanoparticles.

Antibacterial agents based on nanoparticles (NPs) have many important applications, e.g., for the textile industry, surface disinfection, wound dressing, water treatment, and food preservation.

Schottky model for triboelectric temperature dependence.

The triboelectric effect, charging by contact, is the working principle in a device called a triboelectric nanogenerator. They are used as efficient energy transducers in energy harvesting. In such generators the charging of surfaces at contact is followed by a separation of the surfaces increasing the electrical energy which can subsequently be used.

Photoconductivity of acid exfoliated and flash-light-processed MoS films.

MoS has been studied intensively during recent years as a semiconducting material in several fields, including optoelectronics, for applications such as solar cells and phototransistors. The photoresponse mechanisms of MoS have been discussed but are not fully understood, especially the phenomenon in which the photocurrent slowly increases. Here, we report on a study of the photoresponse flash-light-processed MoS films of different thicknesses and areas.

Sintering Inhibition of Silver Nanoparticle Films via AgCl Nanocrystal Formation.

Electrically conductive films are key components in most printed and flexible electronics applications. For the solution processing of conductive films, inks containing silver nanoparticles (AgNPs) remain important because of their relatively easy processing and generally low resistivity after a sintering procedure. Because the commonly used, moderate sintering temperatures of 150-300 °C are still too high for most low-cost flexible substrates, expanding the knowledge of surface-ink interactions that affect the sintering temperature is desirable.

Metal-free supercapacitor with aqueous electrolyte and low-cost carbon materials.

Electric double-layer capacitors (EDLCs) or supercapacitors (SCs) are fast energy storage devices with high pulse efficiency and superior cyclability, which makes them useful in various applications including electronics, vehicles and grids. Aqueous SCs are considered to be more environmentally friendly than those based on organic electrolytes. Because of the corrosive nature of the aqueous environment, however, expensive electrochemically stable materials are needed for the current collectors and electrodes in aqueous SCs.

Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors.

Symmetric electric double-layer capacitors (EDLCs) have equal masses of the same active material in both electrodes. However, having equal electrode masses may prevent the EDLC to have the largest possible specific capacitance if the sizes of the hydrated anions and cations in the electrolyte differ because the electrodes and the electrolyte may not be completely utilized. Here we demonstrate how this issue can be resolved by mass balancing.

Large-Scale Production of Nanographite by Tube-Shear Exfoliation in Water.

The number of applications based on graphene, few-layer graphene, and nanographite is rapidly increasing. A large-scale process for production of these materials is critically needed to achieve cost-effective commercial products. Here, we present a novel process to mechanically exfoliate industrial quantities of nanographite from graphite in an aqueous environment with low energy consumption and at controlled shear conditions.

Exfoliated MoS2 in Water without Additives.

Many solution processing methods of exfoliation of layered materials have been studied during the last few years; most of them are based on organic solvents or rely on surfactants and other funtionalization agents. Pure water should be an ideal solvent, however, it is generally believed, based on solubility theories that stable dispersions of water could not be achieved and systematic studies are lacking. Here we describe the use of water as a solvent and the stabilization process involved therein.

Inkjet Fabrication of Copper Patterns for Flexible Electronics: Using Paper with Active Precoatings.

Low-cost solution-processing of highly conductive films is important for the expanding market of printed electronics. For roll-to-roll manufacturing, suitable flexible substrates and compatible postprocessing are essential. Here, custom-developed coated papers are demonstrated to facilitate the inkjet fabrication of high performance copper patterns.

Thermally reduced kaolin-graphene oxide nanocomposites for gas sensing.

Highly sensitive graphene-based gas sensors can be made using large-area single layer graphene, but the cost of large-area pure graphene is high, making the simpler reduced graphene oxide (rGO) an attractive alternative. To use rGO for gas sensing, however, require a high active surface area and slightly different approach is needed. Here, we report on a simple method to produce kaolin-graphene oxide (GO) nanocomposites and an application of this nanocomposite as a gas sensor.