Typically, batteries and accumulators are used to store energy, which provide energy to electronic devices.
Unlike batteries, they can quickly accumulatea large amount of energy and discharge it just as quickly. If, for example, a train slows down when entering a station, supercapacitors store energy and provide it again when the train quickly needs a lot of energy to start.
However, today one of the problemssupercapacitors was their lack of energy density. While lithium batteries achieve energy densities of up to 265 kWh per kilogram, supercapacitors so far only deliver a tenth of that level.
A team of scientists working with a professorinorganic and organometallic chemistry at the Technical University of Munich (TUM), has developed a new, powerful and sustainable hybrid graphene material for supercapacitors. It serves as a positive electrode in an energy storage device. The researchers are combining it with a proven titanium and carbon negative electrode.
New energy storage device not onlyprovides an energy density of up to 73 kWh / kg, which is roughly equivalent to the energy density of a nickel-metal hydride battery. That being said, the new device performs much better than most other supercapacitors at a power density of 16 kWh / kg. The secret of the new supercapacitor lies in the combination of different materials, which is why chemists call the supercapacitor “asymmetric”.
To create the new device, the researchers relied on a new strategy to overcome the performance limits of standard materials and use hybrid materials.
Abstract idea of combining basic materialswas moved to supercapacitors. They used a new positive storage electrode with chemically modified graphene as a base and combined it with a nanostructured organometallic framework, the so-called MOF.
Decisive for the characteristics of graphene hybrids are, on the one hand, a large specific surface area and controlled pore sizes, and on the other hand, high electrical conductivity.
For good supercapacitors, largesurface. This allows a correspondingly large number of charge carriers to be collected in the material—this is the basic principle of storing electrical energy. Thanks to clever materials design, the researchers were able to bind graphene acid to a MOF. The resulting hybrid MOFs have a very large internal surface area of up to 900 square meters per gram and are very effective as positive electrodes in a supercapacitor.
Stable connection betweennanostructured components have tremendous advantages in terms of long-term stability: the more stable the connection, the more charge and discharge cycles are possible without significantly degrading performance.
For comparison: a classic lithium battery has a service life of about 5000 cycles. The new cell, developed by the TUM researchers, retains almost 90% capacity even after 10,000 cycles.
Read more
See how the moon appeared. Ancient planet crashed into Earth
Archaeologists have found an ancient burial in the Crimea. There was a "ticket" to the afterlife
Abortion and science: what will happen to the children who will give birth