subject: Researchers are looking for the super battery(B) [print this page] Researchers are looking for the super battery(B)
A key problem is to concentrate as much as electrical energy in the smallest space. Researchers at the Fraunhofer Institute for Chemical Technology (ICT) in Pfinztal near Karlsruhe, therefore, attempt to replace conventional graphite electrodes from a1185 battery with materials from tiny, only a few hundred nanometers thick carbon tubes and fibers. This would dramatically increase the inner electrode surface. Normally, lithium ions move only between the graphite layers of the host lattice. A task that is called intercalation. The Nanokohlenstoff from Pfinztal is also different here: "If nanotubes are deposited lithium-ion addition to the edges and surfaces of material layers. Nanotubes can also be manufactured so that a much larger proportion of occupied Interkalationsschichten of lithium-ion battery ," says Jens Tbke head of ICT at the Department of Applied Electrochemistry.
Meanwhile, the researchers were able to increase the discharge capacity of nano-batteries to about 800 milliampere hours per gram (mAh/g). Classical graphite vgp-bps5 battery provide only 300 mAh / g. Nor is the production of micro-carbon nanotubes-consuming and expensive.
Ten times more lithium ions per gram of silicon can store as an electrode material in comparison to graphite. To the chagrin of the researchers, however, increased fourfold while the original volume of the brittle semiconductor materials. The result: After a few charge cycles to show cracks. Here, too nanostructures to solve the problem. For example, researchers at Stanford University are experimenting with micro-fine silicon tube as an electrode material of battery . In the nanofibers mechanical stresses during loading and unloading can survive obviously much better than normal silicon crystals. In addition, the mini-tubes can be produced with the chip production process from relatively inexpensive.
In the laboratories of Stefan Koller, Institute of Chemical Technology of Materials at the Technical University of Graz are also lithium-ion inspiron 1520 batterytested with silicon electrodes. The Austrian researchers battery is however a containing silicon gel which is deposited on graphite as a substrate material. "It has graphite as a buffer to absorb the large volume changes of silicon in the ion absorption and emission," said Koller. The new material could thus save an unchanged lifetime, more than double the amount of lithium ions. Challenge, however, remains the poor density of the materials in the electrode.
High-performance battery should base on lithium-ion plating,and are used for electric vehicles such as energy, the relatively long time to load the batteries can quickly be the Achilles heel of the technique. Until now, battery experts have always assumed that lithium ions during charging is not fast enough to move through the respective electrode material. A computer simulation, carried out the Gerbrand Ceder, Massachusetts Institute of Technology (MIT) in Cambridge (USA), but then placed near the opposite: the example of the standard material lithium iron phosphate (LiFePO (-4)) showed cedar that lithium-ion moving within the electrode downright brisk. But they are thwarted by the limited number of access channels in the crystal lattice, which are also difficult to reach. The result is a jam of the charge carriers.
