Conversion to renewable energy sources like wind and sun is only a question of time. Because wind and solar radiation vary in strength, the increase in renewable energy sources will cause significant fluctuations in the power grid. These must be absorbed by energy storage systems. This need could be fulfilled by a device known as a supercapacitor. John Q. Xiao and his team at the University of Delaware (Newark, USA) have now developed a new process for the production of electrodes made of nickel oxide/nickel nanocomposites for electrochemical supercapacitors. As the researchers report in the journal Angewandte Chemie, their process is simple and cost-effective, and could be scaled up for industry.
Supercapacitors combine the advantages of conventional capacitors and batteries: Like a capacitor, they can rapidly deliver high current densities on demand; like a battery, they can store a large amount of electrical energy. Supercapacitors consist of electrochemical double-layers on electrodes when they are wetted with an electrolyte. When a voltage is applied, ions of opposite polarity collect at both electrodes, forming whisper-thin zones of immobile charge carriers.
The problem is that most processes for the production of the required nanostructured electrodes are either too sensitive to work at an industrial scale or require the addition of substances that later interfere with the electrodes’ function. Sometimes the electrical resistance of the materials is too high. Xiao’s team has now developed a new process for the production of electrodes from a nickel oxide/nickel nanocomposite that can overcome these obstacles.
The scientists first produce nickel nanoparticles. High-boiling polyalcohols, known as polyols, serve as the reaction medium. These cover the growth surfaces of the seed crystals, forming small spherical particles. The nanoparticles are then pressed together into pellets and deposited onto one side of a very thin platinum sheet, which later acts as the current collector. Annealing at 250 °C forms a layer of nickel oxide (NiO) around the pellet, which is the actual active layer of the supercapacitor. This results in compact, stable, highly porous Ni/NiO electrodes that do not require a support. Potassium hydroxide serves as the electrolyte.
During the charging process, OH– ions are bound to the NiO, giving off electrons. The process is reversed when the stored electrical energy is drawn off as current. Its high granularity gives the material a large inner surface area, providing good diffusion pathways for the ions. At the same time, the conductive network of the metal particles is maintained, which is important for high electrical conductivity. These characteristics are the reason for the surprisingly high capacity of the electrodes as well as their high power density and current density during the charge/discharge cycles.
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201101083
New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)
Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
29.05.2017 | Earth Sciences
29.05.2017 | Life Sciences
29.05.2017 | Physics and Astronomy