In terms of weight and size, batteries have become one of the limiting factors in the continuous process of developing smaller and higher performance electronic devices. To meet the demand for batteries having higher energy density and improved cycle characteristics, researchers have been making tremendous efforts to develop new electrode materials or design new structures of electrode materials. Researchers have now investigated the atomistic nature of the lithiation mechanism in individual tin dioxide nanowires by in situ transmission electron microscope and complementary density functional theory simulation.
Researchers have come up with various electrode materials to improve the performance of supercapacitors, focussing mostly on porous carbon due to its high surface areas, tunable structures, good conductivities, and low cost. Graphene and carbon nanotubes show great potential but are costly. Researchers in Canada have now reported the successful hydrothermal-based synthesis of two-dimensional, yet interconnected, carbon nanosheets with superior electrochemical storage properties comparable to those of state-of-the-art graphene-based electrodes.
Harvesting unexploited energy in the living environment is increasingly becoming an intense research area as the global push to replace fossil fuels with clean and renewable energy sources heats up. There is an almost infinite number of mechanical energy sources all around us - basically, anything that moves can be harvested for energy. This ranges from the very large, like wave power in the oceans, to the very small like rain drops or biomechanical energy from heart beat, breathing, and blood flow. In an intriguing demonstration, researchers at Georgia Tech have now demonstrated that the technology offered by nanogenerators can also be used for large-scale energy harvesting.
Binders are used in fabricating lithium-ion batteries to hold the active material particles together and in contact with the current collectors. The characteristics of the binder material used are critical for the performance of the battery. In an effort to make a highly functional binder, researchers at KAIST have developed polymers conjugated with mussel-inspired functional groups (catechol groups). Catechol was found to play a decisive role in the exceptional wetness-resistant adhesion.
Fuel cells are able to convert chemical energy to electrical energy with little pollutant emission and high energy conversion efficiency. Despite these advantages, the performance of fuel cells depends largely on the oxygen reduction reaction (ORR), which is substantially affected by the activity of the cathode catalyst. Since the sluggish kinetics of ORR is the major factor impeding large-scale application of fuel cells, most research focuses on developing efficient catalysts for ORR.
The future of electronics will be flexible. Not only will you be able to roll up your iPads and smart phones like a piece of paper, electronic devices will be invisibly embedded in the textiles you wear from baby diapers to doctors' surgical gloves. To realize such devices, equally flexible power sources need to be integrated with the electronic devices. Textile yarns are an obvious choice. Researchers are already pushing ahead with electronic textiles (e-textiles), for instance by coating regular cotton yarns with single-walled and multi-walled carbon nanotubes and polyelectrolytes, thus making cotton fibers conductive. Addressing the power source issue, researchers have now found a simple way to provide cotton with a new function - storing energy.
Commercially available supercapacitors store energy in two closely spaced layers with opposing charges and offer fast charge/discharge rates and the ability to sustain millions of cycles. Researchers have come up with various electrode materials to improve the performance of supercapacitors, focussing mostly on porous carbon due to its high surface areas, tunable structures, good conductivities, and low cost. Researchers at KAUST now have developed novel supercapacitor electrodes with remarkable pseudocapacitance. They used a scheme of current collector dependent self-organization of mesoporous cobalt oxide nanowires has been used to create unique supercapacitor electrodes, with each nanowire making direct contact with the current collector.
Graphene-based materials are emerging as highly attractive materials for real applications, especially in the area of energy conversion and storage. There are four major energy-related areas where graphene will have an impact: solar cells, supercapacitors, lithium-ion batteries, and catalysis for fuel cells. A recent review gives a brief overview of the recent research concerning chemical and thermal approaches toward the production of well-defined graphene-based nanomaterials and their applications in energy-related areas. But before graphene-based nanomaterials and devices find widespread commercial use, two important problems have to be solved: one is the preparation of graphene-based nanomaterials with well-defined structures, and the other is the controllable fabrication of these materials into functional devices.